Title of Invention

HUMANIZED IMMUNOMODULATORY MONOCLONAL ANTIBODIES FOR THE TREATMEN OF NEOPLASTIC DISEASE OR IMMUNODEFICIENCY

Abstract The present invention provides a humanized monoclonal antibody having immuno-stimulatory effects, an isolated polynucleotide sequence encoding same, methods of producing said humanized antibody and use of said humanized antibody for the preparation of an anti-cancer medicament. The humanized antibody comprises CDRs derived from the murine antibody produced by the hybridoma cell line deposited at the CNCM under Accession No. I-1397 and FRs comprising mainly residues from a human origin. A complicated and innovative analysis led to the replacement of certain human residues in the framework of the variant portion with the original murine antibody. The resulting humanized antibody is composed of an unexpected amino acid sequence and is capable of eliciting an anti-tumor activity similar or greater than the anti-tumor activity induced by the corresponding murine antibody.
Full Text HUMANIZED IMMUNOMODULATORY MONOCLONAL ANTIBODIES FOR THE
TREATMENT OF NEOPLASTIC DISEASE OR IMMUNODEFICIENCY
FIELD OF THE INVENTION
The present invention relates to the field of imrmmotherapy and more specifically
concerns humanized monoclonal antibodies useful for therapy of a variety of indications,
particularly in the treatment of cancer.
BACKGROUND OF THE INVENTION
Cancer in its different forms is a major cause of death in humans. The most widely used
therapeutic treatments of cancer are surgery, radiation and chemotherapy. The rapid increase of
knowledge in recent years about the molecular and cellular bases of immune regulation,
particularly at the level of T-cell responses, provides a new arsenal of immunotherapeutic
approaches including the development of tumor vaccines. Certain monoclonal antibodies
(mAbs) were shown to have immunomodulatory activity including the ability to bind
determinants on the surface of T cells and to induce proliferation, activation or differentiation of
these cells.
Monoclonal antibodies derived from mouse hybridomas contain substantial stretches of
amino acid sequences that are immunogenic when injected into a human patient, often
eliminating the antibody's therapeutic efficacy after an initial treatment. While the production
of so called "chimeric antibodies" (i.e., mouse variable regions joined to human constant
regions) has proven somewhat successful, a significant immunogenicity impediment remains.
Recombinant DNA technology has been utilized to produce immunoglobulins containing
human framework regions (FRs) combined with complementarity determining regions (CDRs)
from a donor mouse or rat immunoglobulin. These new proteins are called "reshaped" or
"humanized" immunoglobulins and the process by which the donor immunoglobulin is
converted into a human-like immunoglobulin by combining its CDRs with a human framework
is called "humanization". Humanized antibodies are important because they bind to the same
antigen as the original antibodies, but are less immunogenic when injected into humans.
US Patent No. 6,294,654 discloses a modified immunoglobulin molecule or functional
fragment or part thereof (Ig), having an antigenic peptide foreign to the Ig incorporated in one or
more non-CDR loops, and wherein the main outline of the constant domain framework is
maintained. Further disclosed is the use of the modified antibody for therapeutic or
prophylactic use.
US Patent No. 6,074,635 discloses a method for antigen independent activation of T cells in
vitro comprising contacting T cells in the absence of antigen with a combination of at least two
cytokines selected from the group consisting of interleukin-2, interleukin-6, and tumor necrosis
factor alpha, or functionally equivalent fragments thereof.
US Patent No. 5,658,741 discloses a method of inducing the activation and proliferation of T-
cells, said method comprising: (a) conjugating a plurality of T-cell specific monoclonal antibodies to
an aminodextran molecule having 7-20% by weight amine groups and a molecular weight of at least
100,000 daltons, wherein the molar ratio of said antibodies to said aminodextran is greater than or
equal to two; and (b) reacting said conjugate with a sample containing said T-cells to effect the
binding of said conjugated antibodies to said T-cells to induce activation and proliferation of said T-cells.
US Patent 5,585,089 of Queen et al. discloses a humanized immunoglobulin having
complementarity determining regions (CDRs) from a donor immunoglobulin and heavy and light
chain variable region frameworks from human acceptor immunoglobulin heavy and light chains,
which humanized immunoglobulin specifically binds to an antigen with an affinity constant of at
least 107 M"1 and no greater than about four-fold that of the donor immunoglobulin, wherein said
humanized immunoglobulin comprises amino acids from the donor immunoglobulin framework
outside the Kabat and Chothia CDRs, wherein the donor amino acids replace corresponding amino
acids in the acceptor immunoglobulin heavy or light chain frameworks, and each of said donor amino
acids: (I) is adjacent to a CDR in the donor immunoglobulin sequence, or (II) contains an atom
within a distance of 4A of a CDR in said humanized immunoglobulin.
WO 91/09967 of Adair et al. discloses CDR-grafted antibody heavy and light chains that
comprise acceptor framework and donor antigen binding regions, the heavy chains comprising donor
residues in at least one of positions (6, 23) and/or (24, 48) and/or (49, 71) and/or (73, 75) and/or (76)
and/or (78) and (88) and/or (91). The CDR-grafted light chains comprise donor residues at the at
least one of positions (1) and/or (3) and (46) and/or (47) or at the at least one of positions (46, 48, 58)
and (71). The CDR-grafted antibodies are preferably humanised antibodies, having non human, e.g.
rodent, donor and human acceptor frameworks.
US Patent 5,225,539, of Winter, discloses an altered antibody or antigen-binding fragment
thereof, wherein a variable domain of the antibody or antigen-binding fragment has the framework
regions of a first immunoglobulin heavy or light chain variable domain and the complementarity
determining regions of a second immunoglobulin heavy or light chain variable domain, wherein said
second immunoglobulin heavy or light chain variable domain is different from said first
immunoglobulin heavy or light chain variable domain in antigen binding specificity, antigen binding
affinity, species, class or subclass.
US 5,225,539, WO 91/09967 and US Patent 5,585,089 do not provide sufficient tools and
comprehensive description for carrying out the synthesis of an altered antibody, particularly a
humanized antibody, by a person skilled in the art.
US 5,618,920 relates to the secretion of heavy chain immunoglobulin fragments and light chain
immunoglobulins from prokaryotic hosts using a prokaryotic secretion signal peptide. US 5,618,920
does not disclose nor claim production of immunoglobulins in human hybridoma cell lines.
US Patent No. 5,897,862 of one of the inventors of the present invention which is incorporated
herein by reference, discloses a monoclonal antibody or an antigen binding fragment thereof, wherein
the monoclonal antibody: (i) is secreted by the hybridoma cell line deposited at the Collection
Nationale de Cultures de Microorganismes (CNCM), under Accession No. 1-1397, or (ii) recognizes
the same antigenic epitope as the antibody under (i). The monoclonal antibody disclosed in
US5,897,862 is directed against "Daudi" cells, a human B lymphoblastoid cell line, and was shown
to stimulate murine lymphocytes and human peripheral blood T cells (Hardy et al, Cell Immunol.
118:22. 1989). This murine antibody is also termed mBAT-1 hereinafter. mBAT-1 also exhibits
anti-tumor and immunostimulatory effects in various types of tumors (Hardy et al., Int. J. Oncol.
12:897, 2001) including tumors of human origin (Hardy et al., Proc. Natl. Acad. Sci. USA 94:5756, 1997).
International Patent Application WO 00/58363 of one of the inventors of the present invention
which is incorporated herein by reference, discloses a monoclonal antibody having a variable region
comprising the heavy chain variable region and/or the Kappa light chain variable region of mBAT-1
or a heavy chain variable region and/or a Kappa light chain variable region having at least 70%
identity to the heavy chain variable region and/or the Kappa light chain variable region of mBAT-1.
Nowhere in the background art is it taught or suggested that a humanized monoclonal antibody
comprising CDRs of a murine origin and FRs of a human origin may elicit an immune response and
may further exhibit anti-cancer activity. Moreover, there is an unmet need for reliable methods for
designing functional humanized antibodies, as it is well known in the art that the synthesis of the
humanized antibody of the present invention cannot be predictably or routinely based on the
background art.
SUMMARY OF THE INVENTTION
It is an object of the present invention to provide a humanized monoclonal
immunomodulatory antibody, also termed hereinafter hBAT-1, which binds to B
lymphoblastoid cells and induces proliferation and activation of peripheral blood lymphocytes.
Said hBAT-1 is based on the previously known murine monoclonal immunomodulatory
antibody, also termed herein mBAT-1, which binds to B lymphoblastoid cells and induces
proliferation and activation of peripheral blood lymphocytes and further elicits an anti-tumor
effect when injected into a tumor.-bearing subject.
The present invention provides a comprehensive description of the humanization process
of mBAT-1 along with the rationale for each synthesis step. Thus, the description of the
humanization process provided in the present invention is suitable for humanization of BAT
antibodies other than mBAT-1, by a person skilled in the art.
The administration of humanized BAT-1 antibody offers a method for therapeutic
prevention, detection or treatment of cancer. Treatment of a subject in need thereof with the
humanized form of the BAT-1 antibody, as provided by the present invention, is considerably
more efficient than treatment with a chimeric BAT-1 antibody, and avoids adverse
irnrnunogenic responses.
The present invention is based in part on the unexpected finding that the humanized BAT-
1 antibody appears to induce a greater anti-tumor effect than that induced by the parent murine
BAT-1 antibody.
According to a first aspect, the present invention provides a humanized monoclonal
antibody comprising at least one CDR from a donor immunoglobulin and an FR from an
acceptor inimunoglobulin.
According to one embodiment, the present invention provides a humanized monoclonal
immunomodulatory antibody comprising at least one CDR from a donor immunoglobulin and
an FR from an acceptor immunoglobulin.
According to another embodiment, the present invention provides a monoclonal
immunomodulatory antibody wherein the donor of CDRs is the murine monoclonal BAT-1
antibody (mBAT-1).
According to yet another embodiment, the present invention provides a monoclonal
immunomodulatory antibody wherein the acceptor from which the FR is derived is a human
immunoglobulin.
According to yet another embodiment, the present invention provides a monoclonal
immunomodulatory antibody comprising at least one CDR from a donor murine monoclonal
BAT-1 antibody (mBAT-1) and an FR derived from an acceptor human immunoglobulin
wherein the humanized antibody retains the biological activity of mBAT-1 monoclonal antibody
and is less immunogenic in a human subject than said murine antibody.
According to yet another embodiment, the light chain variable region of the humanized
BAT-1 antibody is characterized by the formula:
FRl1-CDR l1- FRL2-CDRL2- FRL3-CDRL3- FRL4
wherein each FR is independently a framework region of a human antibody and each CDR is
independently a complementarity determining region of the monoclonal mBAT-1 antibody.
According to yet another embodiment, the heavy chain variable region of the humanized
BAT-1 antibody is characterized by the formula:
FRh1-CDR h1- FRH2-CDRH2- FRh3-CDRh3- FRH4
wherein each FR is independently a framework region of a human antibody and each CDR is
independently a complementarity detennining region of the monoclonal mBAT-1 antibody.
According to a specific embodiment, the present invention provides a monoclonal
antibody comprising FRs derived from the light chain variable region of the human TEL9
antibody.
According to another specific embodiment, the present invention provides a monoclonal
antibody comprising FRs amino acid sequences derived from the light chain variable region of
the human TEL9 antibody selected from the group consisting of: FRL1, [EIVLT QSPSS LSASV
GDRVT ITC; SEQ. ID NO. 1]; FRl2, [W (F or Y) QQKPG KAPKL (W or L) IY; SEQ. ID NO.
2]; FRL3, [GVPSR FSGSG SGT (D or S) (Y or F) (C or T) LTINS LQPED FATYY C; SEQ. ID
NO. 3]; FRL4, [FGGGT KLEIK; SEQ. ID NO. 4].
According to yet another specific embodiment, the present invention provides a
monoclonal antibody comprising FRs derived from the heavy chain variable region of the
human hsighv 1295 antibody.
According to yet another specific embodiment, the present invention provides a
monoclonal antibody comprising FRs amino acid sequences derived from the heavy chain
variable region of the human hsighvl295 antibody selected from the group consisting of: FRhi,
[Q (I or V) QLV QSGSE LKKPG ASVKI SCKAS GY (T or S) F (T or S); SEQ. ID NO. 5];
FRH2, [WV (R OR K) QAPGQ GL (Q or K) WMG; SEQ. ID NO. 6]; FRH3, [RF (V or A)
FSLDT SV (N or S) TAYLQ ITSL (T or N) AEDTG MYFC (V or A) (R or K); SEQ. ID NO.
7]; FRH4, [WGQGT LVTVS S; SEQ. ID NO. 8].
According to yet another preferred embodiment, the present invention provides a
monoclonal antibody comprising a light chain variable region comprising the amino acid
sequence selected from the group consisting of: CDRL1 [SARSS VSYMH; SEQ. ID NO. 9];
CDRl2 [RTSNL AS; SEQ. ID NO. 10]; CDRL3 [QQRSS FPLT; SEQ. ID NO. 11], wherein the
CDRs are derived from the murine BAT-1 antibody and the subscripts "L" and "H" refer to light
and heavy chain regions, respectively.
According to yet another specific embodiment, the present invention provides a
monoclonal antibody comprising a heavy chain variable region comprising the amino acid
sequence selected from the group consisting of: CDRH1 [NYGMN; SEQ. ID NO. 12]; CDRh2
[WINTD SGESTYAEEFKG; SEQ. ID NO. 13]; CDRH3 [VGYDALDY; SEQ. ID NO. 14].
According to yet another embodiment, the humanized monoclonal antibody of the
invention is selected from the group consisting of: a full length antibody having a human
immunoglobulin constant region, a monoclonal IgG particularly of subclasses ?1 or y4, a single
chain antibody, an antibody fragment including, but not limited to, an F(ab')2 fragment or F(ab)
or Fv, a labeled antibody, an immobilized antibody, an antibody conjugated with a heterologous
compound.
According to yet another preferred embodiment, the present invention provides a
monoclonal antibody comprising a light chain variable region selected from the group consisting
of: BATRka (SEQ. ID NO. 15), BATRkb (SBQ. ID NO. 16), BATRkc (SEQ. ID NO. 17),
BATRkd(SEQ. ID NO. 18).
According to yet another preferred embodiment, the present invention provides a
monoclonal antibody comprising a heavy chain variable region selected from the group
consisting of: BATRHA (SEQ. ID NO. 20), BATRHB (SEQ. ID NO. 21), BATRHc (SEQ. ID
NO. 22), BATRHd (SEQ. ID NO. 23) or BATRHE (SEQ. ID NO. 24).
According to yet another preferred embodiment, the present invention provides a
monoclonal antibody comprising a variable region selected from the group consisting of:
BATRHa/BATRka (SEQ. ID NO. 20/SEQ. ID NO. 15), BATRHb/BATRka (SEQ. ID NO.
21/SEQ. ID NO. 15), BATRHb/BATRkb (SEQ. ID NO. 21/SEQ. ID NO. 16),
BATRHc/BATRkb (SEQ. ID NO. 22/SEQ. ID NO. 16), BATRHb/BATRkd (SEQ. ID NO.
21/SEQ. ID NO. 18), or BATRKc/BATRkd (SEQ. ID NO. 22/SEQ. ID NO. 18).
According to yet another embodiment, the humanized monoclonal antibody of the
invention is generated by recombinant DNA technology, utilizing CDR grafting.
According to a second aspect, the present invention provides polynucleotides encoding the
humanized antibody of the invention or fragments thereof. The polynucleotides may encode the
whole humanized antibody or the light chain variable region or the heavy chain variable region
or both chains of the variable region of the humanized antibody. The invention further provides
vectors comprising polynucleotides encoding the humanized antibody of the invention or
fragments thereof. Consequently, the humanized BAT-1 antibody may be expressed in a host
cell following co-transfection of the heavy and light chain vectors or by transfection of a single
vector comprising both light and heavy chain polynucleotide sequences.
According to another embodiment, the present invention provides polynucleotide
sequences encoding the humanized monoclonal antibody of the invention or fragments thereof.
According to another preferred embodiment, the present invention provides a
polynucleotide sequence encoding the kappa light chain variable region of the humanized
antibody of the invention wherein the kappa light chain variable region is selected from the
group consisting of: SEQ ID NO. 15, SEQ ID NO. 16, SEQ ID NO. 17, SEQ ID NO. 18.
According to another preferred embodiment, the polyrmcleotide sequence encoding the
light chain of the humanized antibody of the invention is selected from the group consisting of:
SEQ ID NO. 87, SEQ ID NO. 88, SEQ ID NO. 89.
According to another preferred embodiment, the present invention provides a
polynucleotide sequence encoding the heavy chain variable region of the humanized antibody of
the invention wherein the heavy chain variable region is selected from the group consisting of:
SEQ ID NO. 20, SEQ-ID NO. 21, SEQ ED NO. 22, SEQ ID NO. 23, SEQ ID NO. 24.
According to yet another preferred embodiment, the polynucleotide sequences encoding
the heavy chain of the humanized antibody of the invention are selected from the group
consisting of: SEQ ID NO. 90, SEQ ID NO. 91, SEQ ID NO. 92.
According to yet another embodiment, the present invention provides a vector comprising
the polynucleotide sequence encoding the humanized BAT-1 antibody or fragments thereof.
According to yet another embodiment, the present invention provides a vector comprising
the polynucleotide sequence encoding the humanized antibody of the invention or fragments
thereof.
According to yet another embodiment, the present invention provides a vector comprising
the polynucleotide sequence encoding the humanized antibody of the invention or fragments
thereof selected from the group consisting of: whole humanized antibody, the light chain
variable region, the heavy chain variable region, both chains of the variable region.
According to yet another preferred embodiment, the present invention provides a vector
comprising a polynucleotide sequence encoding the kappa light chain variable region of the
humanized antibody of the invention, wherein the kappa light chain variable region is selected
from the group consisting of: SEQ ID NO. 15, SEQ ID NO. 16, SEQ ID NO. 17, SEQ ID NO.
18.
According to yet another embodiment, the vector further comprises at least one sequence
encoding a component selected from the group consisting of: resistance genes, promoter, signal
peptide, polyA transcription terminator, selection markers, genomic human kappa constant
region.
According to yet another preferred embodiment, the components of the vector are selected
from the group consisting of: Ampicillin resistance gene, Neomycin resistance gene, HCMV
Immediate Early Promoter, the genomic human kappa constant region, a mouse
immunoglobuhn signal peptide sequence, Kozak sequence, a signal sequence intron, BGH
polyA transcription terminator, a Neo/G418 selection marker, a hamster dhfr selection marker.
According to yet another preferred embodiment, the present invention provides a vector
comprising a polynucleotide sequence encoding the heavy chain variable region of the
humanized antibody of the invention, wherein the heavy chain variable region is selected from
the group consisting of: SEQ ID NO. 20, SEQ ID NO. 21, SEQ ID NO. 22, SEQ ID NO. 23,
SEQ ID NO. 24.
According to yet another embodiment, the vector further comprises at least one sequence
encoding a component selected from the group consisting of: resistance genes, promoter, signal
peptide, polyA transcription terminator, selection markers, the genomic human Ig constant
region.
According to yet another preferred embodiment, the components of the vector are selected
from the group consisting of: Ampicillin resistance gene, Neomycin resistance gene, HCMV
Immediate Early Promoter, the genomic human IgG1 constant region, a mouse immunoglobulin
signal peptide sequence, Kozak sequence, a signal sequence intron, BGH polyA transcription
terminator, a Neo/G418 selection marker, a hamster dhfr selection marker,,
According to yet another preferred embodiment, the present invention provides a vector
comprising a polynucleotide sequence encoding the kappa light chain variable region of the
humanized antibody of the invention selected from the group consisting of: pKN110-BATRKA,
pKN110-BATRkb and pKN110-BATRkd.
According to yet another preferred embodiment, the present invention provides a vector
comprising a polynucleotide sequence encoding the heavy chain variable region of the
humanized antibody of the invention selected from the group consisting of: pGlDllO-
BATRHa, pG1D110-BATRHb, pGlD110-BATRHc.
According to yet another preferred embodiment, the present invention provides, a vector
comprising a polynucleotide sequence encoding the complete humanized antibody of the
invention of SEQ ID NO. 93.
According to a third aspect, the present invention provides cells containing a vector
comprising the polynucleotide sequence encoding the antibody of the invention or fragments
thereof for the purposes of storage, propagation, antibody production and therapeutic
applications.
According to another embodiment, the host cell may be selected from the group consisting
of: CHO, CRO dhfr, NSO, COS, COS7.
According to yet another embodiment, the present invention provides a pharmaceutical
composition comprising as an active ingredient the antibody of the; invention, for use in
diagnosis and therapy.
According to yet another embodiment, the pharmaceutical composition comprising as an
active ingredient the antibody of the invention is preferably used for the treatment of cancer.
According to yet another embodiment, the pharmaceutical composition may be
adrainistered either following detection of primary- or secondary tamors-in a -subject or as-
preventive therapy of a subject having a high risk of developing cancers.
According to yet another preferred embodiment, the humanized antibody of the invention
elicits anti-tumor effects in a variety of tumors.
According to yet another embodiment, the present invention provides a method for
diagnosis or treatment of a disease or a disorder, particularly cancer, comprising administering
to a subject in need thereof, an effective amount of a pharmaceutical composition comprising
the antibody of the invention as an active ingredient
According to yet another embodiment, the antibody of the invention in administered
together with, prior to, or following, the administration of other agents, which can ret in an
additive or synergistic manner with it
According to yet another embodiment, the antibody of the invention in administered
together with, prior to, or following, the administration of agents selected from the group
consisting of: cytoidnes, IL-1 (Enterleuken-1), IL-2, IL-6, IFN-a (mterferon-a), cell vaccines,
antibodies, T-cell stimulatory antibodies, anti-tumor therapeutic antibodies.
According to a particular embodiment of the present invention the humanized BAT
monoclonal antibodies are identical in their function or activity to those produced by cells
deposited under ATCC # (PTA-5189).
Other objects, features and advantages of the present invention will become apparent from
the following detailed description and appended claims.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIGURE1 shows the DNA and peptide sequences of the kappa light chain, variable region (VK)
of the murine BAT-1 antibody.
FIGURE 2 depicts the canonical classes of CDRs in the murine BAT-1 Vk region. "Chothia
Canonical Classes" indicates where the canonical classes as defined by -Chothia and his
colleagues (Chothia et al., 1987, 1989, 1992 ibid; Tramontano et a!., I. Mol. Biol. 215:175,
1990) were used while "Martin Canonical Classes" signifies where the canonical classes defined
by Martin and Thornton (Martin et aL, J. Mol. Biol. 263:800,1996) were used. FR residues are
highlighted in bold.
FIGURE 3 presents the DNA and peptide sequences of the heavy chain variable region (VH) of
the murine BAT-1 antibody.
FIGURE 4 depicts the canonical classes of CDRs in the murine BAT-1 Vh region. "Chothia
Canonical Classes" indicates where the canonical classes as defined by Chothia and his
colleagues (Chothia et al; 1987, 1989, 1992 ibid; Tramontano et al., ibid) were used while
"Martin Canonical Classes" signifies where the canonical classes defined by Martin and
Thornton (Martin et al., ibid) were used. FR residues are highlighted in bold.
FIGURE 5 shows the amino acid sequences of the various versions of the humanized BAT-1
VK region that are proposed (SEQ ID NOS. 15-18). Where the BAT-1 Vk region residues and
the human TEL9 Vk region sequence match a dot [.] is shown. Where no amino acid is present
at a specific residue position a dash [-] is shown. Where an amino acid in the TEL9 FRs is
changed in the humanized BAT-1 Vk region, it is highlighted in bold. The CDRs are described
by the use of the nomenclature [=L1=]. The numbering used is as according to Kabat (Kabat
et al., Sequences of proteins of immunological interest, Fifth Edition, U.S. Department of Health
and Human Services, U.S. Government Printing Office, 1991).
FIGURE 6 presents the amino acid sequences of the various versions of the humanized BAT-1
VH region that are proposed (SEQ ID NOS. 20-24). Where the BAT-1 VH region residues and
the human hsighvl295 VH region sequence match a dot [.] is shown. Where no amino acid is
present at a specific residue position a dash [-] is shown. Where an amino acid in the
hsighv 1295 FRs is changed in the humanized BAT-1 Vh region, it is highlighted in bold. The
CDRs are described by the use of the nomenclature [=H1=], while [-----] denotes part of the
HI structural loop. The numbering used is as according to Kabat (Kabat et al., ibid).
FIGURE 7 shows the DNA (SEQ ID NO. 87) and peptide (SEQ ID NO. 15) sequences of
version A (BATRka) of the reshaped human kappa light chain variable region of the humanized
BAT-1 antibody.
FIGURE 8 shows the DNA (SEQ ID NO. 88) and peptide (SEQ ID NO. 16) of version B
(BATRkb) of the reshaped human kappa light chain variable region of the humanized BAT-1
antibody.
FIGURE 9 presents the DNA (SEQ ID NO. 89) and peptide (SEQ ID NO. 18) sequences of
version D (BATRkd) of the reshaped human kappa light chain variable region of the humanized
BAT-1 antibody.
FIGURE 10 is a diagrammatic representation of the pKNUO-BATRKD vector construct.
FIGURE 11 is a diagrammatic representation of the BAT-1 light chain cassette inserted into
BAT-1 light chain expression vectors.
FIGURE 15 is a diagrammatic representation of the pG1D1 10.BAT-1.RHc vector construct.
FIGURE 16 is a diagrammatic representation of the BAT-1 heavy chain cassette inserted into
BAT-1 heavy chain expression vectors.
FIGURE 17 is a diagrammatic representation of the pGlD200 gamma-1 immunoglobulin
heavy chain mammalian expression vector.
FIGURE 18 is a diagrammatic representation of the pGlKD210.BAT-1.RHC/RED single
expression vector (SEQ ID NO. 93).
FIGURE 19 is a diagrammatic representation of the BATRkd/BATRHc heavy and light chains
cassette inserted into a single expression vector for the expression of the complete BAT-1
antibody.
FIGURE 20 shows a Daudi cell BLISA of humanized BATRHb/BATRkb variant against BAT-
1 chimeric antibody.
FIGURE 21 shows a Daudi cell ELISA of humanized BATRHb/BATRka and
BATRHa/BATRka variants against BAT-1 chimeric antibody.
FIGURE 22 shows a Daudi cell ELISA of humanized BATRHc/BATRkb and
BATRHc/BATRkd variants against BAT-1 chirneric antibody.
FIGURE 23 shows a Daudi cell ELISA of humanized BATRHb/BATRkd variant against BAT-
1 chimeric antibody.
FIGURE 24 presents dose dependence binding curves to Daudi cells of the murine BAT-1 mAb
and the humanized BATRHc/BATRkd yl mAb.
FIGURE 25 illustrates the .dose-dependent anti-metastatic activity of the humanized
BATRHc/BATRkd yl mAb (KBAT) in murine B16 lung tumors, with respect to control (no
treatment) and to treatment with the original murine BAT-1 mAb. All treatments were
administered intravenously 14 days post tumor inoculation and lungs were examined 10 days
post treatment.
FIGURE 26 represents the inhibitory effect of the humanized BATRHc/BATRkd yl mAb on
human melanoma (SK-28) in SCID mice engrafted with human lymphocytes. The effect of the
humanized BAT-1 on tumor growth is compared with control (no treatment) or treatment with
the murine BAT-1 mAb (mBAT-1).
FIGURE 27 demonstrates the anti-metastatic activity of the humanized BATRHc/BATRkd yl
mAb in a Murine Tumor Model (HM7) implanted in BALB/c nude mice.
FIGURE 28 shows co-localization of the humanized BATRHc/BATRkd yl mAb (hBAT) with
CD4 (A) and CDS (B) determined by flow cytometry on gated lymphocytes.
FIGURE 29 presents binding of the humanized BATRHc/BATRkd ?1 mAb to cellular markers
CD19 (A) and CD20 (B) of B lymphocytes isolated from a normal donor.
FIGURE 30 represents the binding of the humanized BAT mAb to non-activated (day 0, A; day
5, C) and activated (2 days, B; 5 days, D) CD4+ T cells.
FIGURE 31 shows the binding of the humanized BAT mAb to CD69+ T cells activated with
beads conjugated to anti-CD3 and anti-CD28 in a dose-dependent manner (no activation, A;
0.25 µ1, B; 0.5 µ1, C).
FIGURE 32 presents co-localization of the humanized BATRHc/BATRkd ?1 mAb with CD25
marker of T cells in a time dependent manner: day 0, A; day 2 and day 5 of activation, B and D
respectively; day 5 of no activation, C.
FIGURE 33 shows co-localization of the humanized BATRHc/BATRkd ?2 and day 5 of
activation, B - C and E, respectively; day 5 of no activation, D.
FIGURE 34 describes hBAT induced increase in the number of viable CD4+ cells, isolated
from two separate donors (A and B).
FIGURE 35 presents hBAT binding to Daudi (A) and Jurkat (B) cell lines.
FIGURE 36 demonstrates hBAT binding to PBL of cancer patients.
DETAILED DESCRIPTION OF THE INVENTION
I. Definitions
For convenience certain terms employed in the specifications, examples and claims are
set forth.
The term "antibody" is used in the broadest sense and specifically covers monoclonal
antibodies (including full length monoclonal antibodies) and antibody fragments so long as they
exhibit the desired biological activity. "Antibody fragments" comprise a portion of a full length
antibody, generally the antigen binding or variable region thereof. Examples of antibody
fragments include Fab, Fab', F(ab')2, and Fv fragments; diabodies; linear antibodies; single-chain
antibody molecules; and multispecific antibodies formed from antibody fragments.
The term "monoclonal antibody" as used herein refers to antibodies that are highly
specific, being directed against a single antigenic site. The monoclonal antibodies to be used in
accordance with the present invention may be made by recombinant DNA methods (see, e.g.,
U.S. Patent 4,816,567 of Cabilly et al.).
The term "framework region" or "FR" residues are those variable domain residues other
than the hypervariable region residues as herein defined. The term "hypervariable region" when
used herein refers to the amino acid residues of an antibody which are responsible for antigen
binding. The hypervariable region comprises amino acid residues from a "complementarity
determining region" or "CDR". The CDRs are primarily responsible for binding to an epitope of
an antigen. The extent of FRs and CDRs has been precisely defined (see, Kabat et al., ibid).
As used herein, the term "humanized antibody" refers to an antibody comprising a
framework region from a human antibody and one or more CDRs from a non-human (usually a
mouse or rat) immunoglobulin. Parts of a humanized immunoglobulin, except possibly the
CDRs, are substantially identical to corresponding parts of natural human immunoglobulrn
sequences. Importantly, the humanized antibody is expected to bind to the same antigen as the
donor antibody that provides the CDRs. For further details, see e.g. US. Pat. No. 5,225,539
assigned to Medical Research Council, UK.
The expression "human antibody" is intended to mean an antibody encoded by a gene
actually occurring in a human, or an allele, variant or mutant thereof.
As used herein, the term "donor" or "parental" immunoglobulin refers to the non-human
immunoglobulin providing the CDRs.
As used herein, the term "acceptor" immunoglobulin refers to the human immunoglobulin
providing the framework.
The term "expression vector" as used herein refers to a recombinant DNA molecule
containing a desired coding sequence and appropriate nucleic acid sequences necessary for the
expression of the operably linked coding sequence in a particular host cell. It is contemplated
that the present invention encompasses expression vectors that are integrated into host cell
genomes, as well as vectors that remain unintegrated into the host genome.
The term "genetically modified cells" as referred to herein relates to cells being
transfected or infected by a vector, as exemplified by a virus encoding a polyp eptide of interest,
said cells capable of expressing said polypeptide. Particularly in the context of this invention,
the genetically modified cells are capable of expressing and secreting the antibody of the
invention.
The term "transfection" refers to the introduction of DNA into a host cell. It is
contemplated that coding sequences may be expressed in transfected cells. Numerous methods
of transfection are known to the ordinary skilled artisan, for example, CaPCv and
electroporation.
The term "anti-tumor effect" as used herein, refers to a biological effect which can be
manifested by a decrease in tumor volume, a decrease in the number of tumor cells, a decrease
in the number of metastases, an increase in life expectancy, or amelioration of various
physiological symptoms associated with the cancerous condition. An "anti-tumor effect" can
also be manifested by the ability of the antibody of the invention in prevention of the occurrence
of tumor in the first place. Given its properties, the antibody of the invention can be used both in
the treatment of acute cancer as well as in cancer prophylaxis.
Herein the term "excipient" refers to an inert substance added to a pharmaceutical
composition to further facilitate administration of a compound. Examples, without limitation, of
excipients include calcium carbonate, calcium phosphate, various sugars and types of starch,
cellulose derivatives, gelatin, vegetable oils and polyethylene glycols. Pharmaceutical
compositions may also include one or more additional active ingredients.
The term "Polymerase Chain Reaction" ("PCR") refers to the methods disclosed in U.S.
Pat. Nos. 4,683,195; 4,683,202, and 4,965,188.
II. Preferred modes for carrying out the invention
a. Antibody preparation
In order to humanize the BAT-1 antibody, the non-human antibody starting material, namely
mBAT-1 is prepared, following the design and preparation of the humanized variants. Some
aspects of this invention, including the selection of a donor non-human antibody variable
domain, humanizing an antibody gene sequence and producing a desired humanized antibody,
are described in the following sections.
(i) Preparation of the non-humanized antibody
The murine BAT-1 monoclonal antibody was described previously in US Patent
5,897,862. Accordingly, a representative hybridoma cell line that produces monoclonal murine
BAT-1 antibodies, was deposited at the Collection Nationale de Cultures de Microorganismes
(CNCM), Institute Pasteur, 25, Rue du Docteur Roux, 75724, Paris, Cedex 15, under Deposit
Accession No. 1-1397, on Jan. 28, 1994.
Alternatively, the chimeric ?1/ic BAT-1 antibody as produced from the murine BAT-1 may
be used for the preparation of a humanized BAT-1. The chimeric BAT-1 antibody and its
production, have been described in PCT application No. WO 00/58363.
(ii) Design strategy of the humanized antibody
The present invention discloses procedures for hurnanization of BAT-1 antibody via a
process in which the donor antibody, preferably mouse antibody, is converted into a human-like
antibody by combining the CDRs of the donor antibody with a human framework. In certain
embodiments, it may be desirable to generate amino acid sequence variants of the humanized
antibody, particularly where these improve the binding affinity or other properties of the
humanized antibody. The methods applied to select sites for substitution, insertion or deletion,
from both the donor BAT-1 antibody and the selected human acceptor antibody, including the
selection of acceptor human antibodies are described in detail. The extensive analysis and
guidelines for antibody humanization which is provided hereinbelow, is not disclosed in the
background art and is crucial for the preparation of an active altered antibody.
The design of a humanized antibody is preferably initiated by sequence analysis of the
heavy and light chains of the non-human antibody variable region, also termed hereinafter Vh
and Vl, respectively. Such analysis includes a comparison between the amino acid sequence of
Vl and Vh of the non-humanized antibody and other mouse variable regions. In a preferred
embodiment, the comparison can be further conducted with consensus sequences of the
subgroups into which the variable regions were subdivided in the Kabat database (Kabat et al.,
ibid). The classification of the different elements of the variable region facilitates selection of
immunoglobulin variable regions which are similar to the Vl and Vh of the non-humanized
antibody of the present invention and are structurally solved.
Selection of the human kappa light chain variable region, also termed hereinafter Vk, and
of Vh that would serve as the basis of the variable region of the humanized antibody, also
termed an acceptor antibody, is preferably initiated by classifying the Vl and Vh of the non
human antibody according to consensus sequences of human irnmunoglobulins. Particularly, Vl
of the non-humanized antibody is compared with and consequently categorized according to the
consensus sequences of the four human kappa light chain variable region subgroups as defined
by Kabat (Kabat et al., ibid). Similarly, VH of the non-humanized antibody is compared and
categorized according to the consensus sequences of the three human heavy chain variable
region subgroups.
The selection of the acceptor human Vk and Vh is preferably proceeded by conducting a
comparison between Vl and Vh of the parental non-human antibody of the invention and all the
recorded examples of individual sequences of human variable regions publicly available. An
appropriate human Vk and Vh are selected on the basis of closest match to the parental non-
human antibody.
Analysis of the sequences of the donor and humanized antibodies and reference to
appropriate molecular models can help to discern which residues might be involved in antigen
binding or maintenance of proper antibody structure and which residues should be removed or
substituted in order to improve the structure of the humanized antibody.
Molecular models of the variable regions of both the non-human and humanized
antibodies are thus prepared to assist the design of the humanized antibody. The modeling of
these structures are based on the classifications of the variable region elements that were
determined in the analysis procedure and can be obtained, for example, by using homology and
ab initio techniques. The corresponding X-ray crystallographic structures can be obtained from
the Brookhaven database.
Elements within the variable region of the non-human antibody of the invention, such as
FRs, CDRs, and loop structures, are modeled on elements from similar, structurally solved,
immunoglobulin variable regions. Steric clashes are identified in the models and consequently
mismatched side-chains are selected for substitution. A particularly preferred approach for
structure conformation includes categorization of the structural elements according to canonical
classes based on those described by Chothia and his colleagues (Chotbia et al., 1987,1989,1992
ibid; Tramontano et al., ibid). A preferred approach for structure prediction includes a database
search or CONGEN search (Bruccoleri, R.E. et al., Biopofymers 26:137., 1987). The selected
human Vk and Vh that would serve as the basis of the humanized antibody are similarly
modeled and their amino acid sequences are studied to determine if any of their residues are
likely to adversely influence binding specificity.
Energy minimization is preferably applied after adjusting the models for obvious steric
clashes. Energy minimization is implemented here both to relieve unfavorable atomic contacts
and to optimize van der Waals and electrostatic interaction.
As a result of the above design procedure the humanized antibody variants of BAT-1 may
comprise additional, or substituted conservative amino acid residues which are not found in the
recipient antibody or in the donor antibody. Deletion of amino acid residues included in the
original acceptor or donor antibodies may also be applied. These modifications are made to
refine antibody performance and have substantially no effect on antigen binding or other
irrrmunoglobulin functions. The sites of greatest interest for modifications include the
hypervariable loops, but FR alterations are also contemplated. Hypervariable region residues or
FR residues involved in antigen binding are generally substituted in a relatively conservative
manner. The conservative substitutions that may be applied in the present invention comprise
the following options: Val, Ile; Ser, Thr; Lys, Arg; Phe, Tyr; Trp, Leu; Asp, Ser; Cys, Thr; Gln,
Lys; Val, Ala; Asn, Ser; Thr, Asn.
(iii) Construction of the humanized antibody variants
Generally, the BAT-1 antibody variants are conventionally prepared in recombinant cell
culture, as described in more detail below. Recombinant synthesis is preferred here but it is
known to prepare peptides by chemical synthesis or to purify them from natural sources.
Molecular biology techniques and CDR grafting protocols suitable to carrying out the
invention as herein described are known to those skilled in the art. Suitable teachings are
described in numerous manuals and primary publications, including inter alia, Sambrook et al,
(Molecular Cloning: A Laboratory Manual, 2nd Ed., Cold Spring Harbor Laboratory Press, Cold
Spring Harbor, New York, 1989); Ausubel et al., (Protocols In Molecular Biology, Green
Publishing Associates and Wiley-Interscience, John Wiley and Sons, New York 19S7, 1988,
1989); US Patent Nos. 5,225,539 and 5,585,089 which are herein incorporated by reference in
their entirety including supplements.
The amino acid sequences of BAT-1 light and heavy chain CDRs are herein identified and
illustrated in FIG. 5 and 6: CDRL1 (SEQ. ID NO. 9 and SEQ L1 in FIG.5): SARSS VSYMH;
CDRl2 (SEQ. ID NO. 10 and SEQ L2 in FIG.5): RTSNL AS; CDRL3 (SEQ. ID NO. 11 and
SEQ L3 in FIG.5): QQRSS FPLT; CDRH1 (SEQ. ID NO. 12 and SEQ H1 in FIG.6): NYGMN;
CDRh2 (SEQ. ID NO. 13 and SEQ H2 in FIG.6): WINTD SGEST YAEEF KG; CDRH3 (SEQ.
ED NO. 14 and SEQ H3 in FIG.6): VGYDA LDY.
Using these ammo acid sequences, oligonucleotides encoding these CDRs can be
synthesized for use in the present invention. Also, the oligonucleotides may contain nucleotides
in addition to those of BAT-1 CDRs, to facilitate cloning or to introduce restriction sites, for
instance. Oligonucleotide synthesis techniques suitable to this aspect of the invention are well
known to the skilled artisan and may be carried out using any of several commercially available
automated synthesizers. In addition, DNAs encoding the CDRs set forth herein can be obtained
through the services of commercial DNA synthesis vendors. It is thus not necessary to redone
BAT-1 CDRs from a natural source.
mBAT-1 CDRs are grafted into a human antibody to produce the humanized BAT-1
variants. It will be understood that human antibody in this context refers to any antibody that
occurs in a human or an engineered antibody that has been designed, in some respect, to be
compatible with the human immune system. Particularly preferred for this purpose are
antibodies that, broadly, do not engender an adverse immune response in a patient.
To construct CDR-grafted humanized BAT-1 antibodies, oligonucleotides encoding the
.BAT-1 CDRs can be integrated into other DNAs encoding antibody heavy and light chains and
fragments thereof, using well-known recombinant techniques such as those described hi the
above references. Particularly, BAT-1 CDRs can be introduced into practically any set of FRs
in accordance with the present invention. A variety of human antibody genes are available in the
form of publicly accessible deposits and suitable antibody genes can be synthesized from these
sequences much as described above. Preferred techniques employed in this regard, for cloning
and manipulating polynucleotides are illustrated by the methods and examples set forth.
The amino acid sequences of mBAT-1 and reshaped BAT-1 light (FIG. 5) and heavy
(FIG.6) chain FRs and modified FRs are herein identified: FRL1 (SEQ. ID NO. 1): ECVLT
QSPSS LSASV GDRVT ITC; FRL2 (SEQ. ID NO. 2): WXaaQQK PGKAP KLXbbI Y,
wherein Xaa =-F, Y and Xbb = W, L;FRl3 (SEQ. PD NO. 3): GVPSR FSGSG SGTXaaXbb
XcoLTPN SLQPE DFATY YC, wherein Xaa = D, S; Xbb = Y, F and Xcc== C, T; FRL4 (SEQ. ID
NO. 4): FGGGT EXEPK; FRHi (SEQ. ID NO. 5): QXaaQLV QSGSE LKKPG ASVKI SCKAS
GYXbbFXcc, wherein Xaa = I, V; Xbb = T, S; Xcc = T, S; FRh2 (SEQ. ID NO. 6); WVXaaQA
PGQGL XbbXbbWMG, wherein Xaa = R, K; FRH3 (SEQ. ID NO. 7): RFXaaFS LDTSV XbbTAYL
QITSL XccAEDT GMYFC XddXee, wherein Xaa = V, A; Xbb = N, S; Xcc = T, N; Xdd = V,
A; Xee = R, K; FRH4 (SEQ. ID NO. 8): WGQGT LVTVS S.
The oligonucleotides encodingthe BAT-1 CDRs and/or specific FR residues originated
from human antibodies may be used to introduce codons into the DNA encoding Vk or Vh of
the humanized BAT-1 variants. In accordance with this aspect of the invention the additional
codons may include those not derived from BAT-1 CDR as well as those that make up the CDR.
These additional bases may be included to facilitate joining the CDR to the FRs from a
heterologous source. They may comprise restriction sites or overlapping complementary regions
for this purpose. The template DNAs are typically single-stranded DNAs (ssDNAs) vectors.
The CDRs of the BAT-1 heavy and light chains may also be modified particularly after
incorporation into a humanized antibody using well-known recombinant DNA techniques for
deleting, inserting and altering bases in a cloned or synthetic DNA or RNA. Site-specific
mutagenesis techniques suitable to this end are well known to those of skill in the art, and are
illustrated in the foregoing references on recombinant DNA techniques. These methods can be
used to introduce practically any desired alteration into polynucleotides that encode the BAT-1
¦CDRs or into other regions of a closed heavy or light chain gene.
The synthesis of longer, double-stranded DNAs from shorter, overlapping, single-stranded
DNAs is well known to those of skill in the art. Likewise, well known is the end-to-end joining
of DNAs, including blunt-ended DNAs and those with at least partially overlapping
complementary termini. These techniques are illustrated in the foregoing references on
recombinant DNA techniques, for instance.
The construction of all versions of the human BAT-1 variable region is preferably carried
out as described by Stemmer (Stemmer et al., GENE 164:49, 1995). Essentially, this method is
favored for the synthesis of long DNA sequences from large numbers of
oligodeoxyribonucleotides (oligos). The method relies on DNA polymerase using conventional
PCR technique, to build increasingly longer DNA fragments during assembly process. Once the
new variable region gene is synthesized it is preferentially subcloned into a vector which is
transformed into competent cells as described in the above references. Putative positive clones
can be identified by PCR-screening using appropriate primers and/or by restriction digest.
Individual clones selected from the confirmed positive clones may be sequenced to double-
stranded-DNA (ds-DNA). Preferably, the resultant ds-DNAs can be rechecked for PCR-induced
errors, by sequencing, and corrected by subcloning correct fragments from other clones.
DNA of selected clones, from the confirmed positive clone, containing the humanized Vk
or Vh of the BAT-1 variant may be directly inserted into expression vectors which comprise
human light and heavy constant regions, respectively. Once DNA encoding the humanized
BAT-1 CDR-grafted complete antibody variant, or the light or the heavy chain regions of the
humanized BAT-1 CDR-grafted antibody, has been assembled, it may be inserted into a vector
for propagation and expression by conventional techniques. In this manner desired amounts of
the antibody may be obtained.
(iv) Expression of the humanized BAT-1 antibody variants
The invention also provides isolated polynucleotide sequences encoding the complete
humanized BAT-1 antibody, the light chain complete or variable region, heavy chain complete
or variable region sequence, as well as vectors and host cells comprising the coding nucleic acid.
For recombinant production of the BAT-1 antibody, the polynucleotide sequence encoding
said antibody or its fragments, is isolated and inserted into a replicable vector for further
cloning, amplification or for expression. DNA encoding the antibody is readily isolated and
sequenced using conventional procedures (e.g., by using oligonucleotide probes that are capable
of binding specifically to genes encoding the heavy and light chains of the antibody). Many
vectors are available which generally include, but are not limited to, one or more of the
following: a signal sequence, an origin of replication, one or more marker genes, an enhancer
element, a promoter, and a transcription termination sequence.
For expression, the polynucleotide encoding the humanized BAT-1 antibody or fragments
thereof, may be cloned into an expression vector. Such vectors are well known to those skilled
in the art. An expression control sequence, such as an immunoglobulin or viral promoter, is
introduced upstream of the polynucleotide. Selection markers such as the dhfr gene, or other
suitable selectable marker well known to those skilled in the art, are included in the vector to
allow selection of host cells which are expressing the said polynucleotide included on the vector.
In one embodiment, the host cell endogenously produces antibodies, while in an
alternative embodiment, the cell is genetically modified to produce antibodies. Examples of
cells that endogenously produce antibodies include, but are not limited to hybridomas,
lymphomas, plasmacytomas and EBV transformed cells. A cell can be genetically modified to
produce antibodies by conventional methods, such as by transfection with a vector encoding an
antibody molecule.
In use, the expression vector comprising the polynucleotide encoding the humanized BAT-
1 antibody or fragments thereof, is transfected into cells. Transfection methods are well known
in the art and such methods are suitable for employment in the present invention. The cells
expressing the expression vector are selected using the selectable marker incorporated into the
expression vector or a vector used for co-transfection. Cells expressing the antibody can be
screened by enzyme-linked immunoabsorbent assay (ELISA) assays or other suitable methods
well known to those skilled in the art.
The humanized BAT-1 antibody variants are introduced into a host cell by transfection of
a vector comprising polynucleotide encoding the complete or Fv fragment of the antibody.
Humanized BAT-1 antibody variants is also introduced into a host cells by co-transfection of: (i)
a vector comprising polynucleotide encoding the variable or complete light chain region of the
antibody and (ii) a vector comprising polynucleotide encoding the variable or complete heavy
chain region of the antibody.
hi a most preferred embodiment, the antibody of the invention is produced by a
transfection of a single vector comprising polynucleotide sequences encoding the light and
heavy variable regions of the antibody. Most preferably, this vector further comprises two
promoters, each operatively linked to the polynucleotide sequence encoding the light chain and
the heavy chain regions of reshaped BAT-1. The resulting expression of the BAT-1 antibody is
higher than its expression following co-transfection with two vectors, each encoding the light
chain or heavy chain regions, of the antibody, whereas the transfection and co-transfection being
conducted in a similar host cell.
The humanized BAT-1 antibody variants can be expressed in any suitable cell type,
including but not limited to mammalian, avian, insect, bacterial or yeast cells. Examples of
mammalian cells include, but are not limited to, human, rabbit, rodent (e.g., mouse, rat) and
bovine cells. In preferred embodiments, the cell is a myeloma cell, a Chinese hamster ovary
(CHO) cell, COS cell, COS7 cell or fibroblast.
Antibody-producing cell lines may be cultured using techniques well known to the
skilled artisan. Such techniques are described in a variety of laboratory manuals and primary
publications. For instance, techniques suitable for use in the invention as described below are
described in current protocols in immunology, Coligan et al., (Green Publishing Associates and
Wiley-Interscience, John Wiley & Sons, N.Y. 1991) which is herein incorporated by reference
in its entirety, including supplements.
The humanized monoclonal antibodies of the invention can be frozen or lyophilized for
storage and reconstituted in a suitable carrier prior to use. This technique has been shown to be
effective with conventional immune globulins and art-known lyopbilization and reconstitution
techniques can be employed. It will be appreciated by those skilled in the art that lyopbilization
and reconstitution can lead to varying degrees of antibody activity loss and that use levels may
have to be adjusted to compensate.
(v) Purification of humanized BAT-1 antibody
Using recombinant techniques, the antibody can be produced ixttracellularly, in the
periplasmic space, or directly secreted into the medium. If the antibody is produced
intracelmlarly, as a first step the participate debris, either host cells or lysed fragments, is
removed, for example, by centrifugation or ultrafiltration. Carter et al., (Biotechnology .10:163,
1992) describe a procedure for isolating antibodies which are secreted to the periplasmic space
of E. coli. Briefly, cell paste is thawed in the presence of sodium acetate (pH 3.5), EDTA, and
phenylmethylsulfonylfiuoride (PMSF) over about 30 min. Cell debris can be removed by
centrifugation.
In a most preferred embodiment, the antibody of the invention is secreted into the medium,
supernatants from such expression systems are generally first concentrated using a commercially
available protein concentration filter, for example, an Amicon or Millipore ultrafiltration unit. A
protease inhibitor may be included in any of the foregoing steps to inhibit proteolysis and
antibiotics may be included to prevent the growth of adventitious contaminants.
The antibody composition prepared from the cells can be purified using methods well
known in the art, for example, hydroxyapatite chromatography, gel electrophoresis, dialysis, and
affinity chromatography, with affinity chromatography particularly with protein A, being a
preferred purification technique. The matrix to which the affinity ligand is attached is most often
agarose, but other matrices are available. Mechanically stable matrices, such as controlled pore
glass or poly(styrenedivinyl)benzene, allow for faster flow rates and shorter processing times
than can be achieved with agarose. Where the antibody-comprises a CH3 domain, the Bakerbond
ABX™ resin (J. T. Baker, Phillipsburg, N.J.) is useful for purification. Other techniques for
protein purification such as fractionation on an ion-exchange column, ethanol precipitation,
reverse phase HPLC, chromatography on silica, chromatography on heparin SEPHAROSE™,
chromatography on an anion or cation exchange resin (such as a polyaspartic acid column),
chromatofocusing, SDS-page, and ammonium sulfate precipitation are also available depending
on the antibody to be recovered.
(vi) Deposit Of Cell Line
According to a representative embodiment of the present invention the humanized BAT
monoclonal antibodies are identical in their function or activity to those produced by cells
deposited under ATCC # (PTA-5189), on May 9,2003.
IIL Pharmacology
(i) Pharmaceutical compositions
The invention also provides a composition comprising the antibody of the invention.
According to another embodiment, the present invention provides a pharmaceutical
composition comprising as an active ingredient the antibody of the invention, for use in
diagnosis and therapy. Said compositions may be in any pharmaceutical form suitable for
administration to a patient, including but not limited to solutions, suspensions, lyophilized
powders for reconstitution with a suitable vehicle or dilution prior to usage, capsules and tablets.
The pharmaceutical compositions disclosed in this invention may further comprise any
pharmaceutically acceptable diluent or carrier to provide a physiologicalry acceptable
conjugates comprising the antibodies with therapeutic agents for diagnosis, prognosis and
therapy, among others.
Pharmaceutical compositions of the present invention may be manufactured by processes
well known in the art, e.g., by means of conventional mixing, dissolving, granulating, grinding,
pulverizing, dragee-making, levigating, emulsifying, encapsulating, entrapping or lyophilizmg
processes.
Pharmaceutical compositions for use in accordance with the present invention thus may be
formulated in conventional manner using one or more physiologically acceptable carriers
comprising excipients and auxiliaries, which facilitate processing of the active compounds into
preparations which, can be used pharmaceutically. Proper formulation is dependent upon the
route of administration chosen.
For injection, the compounds of the invention may be formulated in aqueous solutions,
preferably in physiologically compatible buffers such as Hank's solution, Ringer's solution, or
physiological saline buffer. For transmucosal administration, penetrants appropriate to the
barrier to be permeated are used in the formulation. Such penetrants, for example polyethylene
glycol, are generally known in the art. Pharmaceutical compositions which can be used orally,
include push-fit capsules.
For administration by inhalation, the molecules for use according to the present invention
are conveniently delivered in the form of an aerosol spray presentation from a pressurized pack
or a nebulizer with the use of a suitable propellant, e.g., dichlorodifluoromethane,
trichlorofluoromethane, dichloro-tetrafluoroethane or carbon dioxide, hi the case of a
pressurized aerosol, the dosage unit may be determined by providing a valve to deliver a
metered amount. Capsules and cartridges of, e.g., gelatin for use in an inhaler or insufflator, may
be formulated containing a powder mix of the polypeptide and a suitable powder base such as
lactose or starch.
Pharmaceutical compositions for parenteral administration include aqueous solutions of
the active ingredients in water-soluble form. Additionally, suspensions of the active compounds
may be prepared as appropriate oily injection suspensions. Suitable natural or synthetic carriers
are well known in the art. Optionally, the suspension may also contain suitable stabilizers or
agents, which increase the solubility of the compounds, to allow for the preparation of highly
concentrated solutions. Alternatively, the active ingredient may be in powder form for
reconstitution with a suitable vehicle, e.g., sterile pyrogen-free water, before use.
Pharmaceutical compositions suitable for use in context of the present invention include
compositions wherein the active ingredients are contained in an amount effective to achieve the
intended purpose. All formulations for administration should be in dosages suitable for the
chosen route of administration. More specifically, a "therapeutically effective" dose means an
amount of a compound effective to prevent, alleviate or ameliorate symptoms of a disease of the
subject being treated. Determination of a therapeutically effective amount is well within the
capability of those skilled in the art, especially in light of the detailed disclosure provided
herein.
Toxicity and therapeutic efficacy of the compositions described herein can be determined
by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., by
determining the IC50 (the concentration which provides 50% inhibition) and the maximal
tolerated dose for a subject compound. The data obtained from these cell culture assays and
animal studies can be used in formulating a range of dosage for use in human. The dosage may
vary depending upon the dosage form employed and the route of administration utilized. The
exact formulation, route of administration and dosage can be chosen by the individual physician
in view of the patient's condition. Depending on the severity and responsiveness of the
condition to be treated, dosing can also be a single administration of a slow release composition,
with course of treatment lasting from several days to several weeks or until cure is effected or
diminution of the disease state is achieved. The amount of a composition to be administered
will, of course, be dependent on the subject being treated, the severity of the affliction, the
manner of administration, the judgment of the prescribing physician, and all other relevant
factors.
(ii) Methods of treatment
Antibodies in accordance with the invention, while being useful for a variety of therapeutic
indications, are used, in accordance with a currently preferred embodiment of the invention, for
the treatment of cancer. It has been found that a monoclonal antibody in accordance with the
invention elicits anti-tumor effects in a variety of tumors. Within the scope of the present
invention, methods are provided for the use of the novel hBAT-1 for the treatment of tumor by
administering to a subject an effective amount of the antibody of the invention. The term
"effective amount" should be understood as meaning an amount of an antibody required to
achieve a therapeutic effect. The effective amount required to achieve the therapeutic end result
may depend on a number of factors including, for example, the tumor type and the severity of
the patient's condition (i.e. the cancerous state), and whether the antibody is co-administered
together with another agent which acts together with the antibody in an additive or synergistic
manner. The antibody may be administered either following detection of primary or secondary
tumors in the subject or, as preventive therapy of a subject having a high risk of developing
cancers, such as an individual exposed to radiation or such having a genetic pre-disposition.
The invention additionally provides a method of treating a subject in need thereof, with a
humanized BAT-1 antibody variant or with a composition that comprises said antibody as an
active ingredient.
According to yet another embodiment, the present invention provides a method for
diagnosis or treatment of a disease or a disorder, particularly cancer, comprising administering
to a subject in need thereof, an effective amount of a pharmaceutical composition comprising
the antibody of the invention as an active ingredient.
The method of treatment comprises administering an antibody or composition of the
invention to a subject. The method of treatment also comprises administration an antibody or
composition of the invention to a subject in parallel to, prior to, or following treatment with an
additional active composition comprising cytokines such as IL-1 (mterleulcen-1), IL -2, IL -6
and FN-a (interferon-a) or other antibodies, such as any T-cell stimulatory antibody or other
anti-tumor therapeutic antibody. In one embodiment, the subject is a human. In another
embodiment the disease to be prevented, treated or detected is cancer.
The administration of said compositions can be typically achieved by means of parenteral
administration, e.g., intravenously (i.v.) mtraperitoneally (i.p.) or intramuscularly (i.m.).
Methods of treatment may comprise pharmaceutical compositions of the antibodies according to
the invention. Alternatively or additionally, methods of treatment may include cell therapy, ex-
vivo or in-vivo wherein cells are autologous or allogeneic.
In order to boost the anti-tumor activity of the antibody, it is at times advantageous to
administer the antibody of the invention together with, prior to, or following, the administration
of other agents, which can act in an additive or synergistic manner with it. Examples comprise
various cytokines, including but not limited to IL-1 (Interleuken-1), 11,-2, IL-6 and IFN-a
(Interferon-a), as well as cell vaccines or additional antibodies, including but not limited to T-
cell stimulatory antibodies, or anti-tumor therapeutic antibodies.
The antibody of the invention may be useful in the therapy of a variety of diseases other
than cancer where activation or other effects of the antibody on the immune system's
proliferative, cytolytic or stimulatory activity may have a therapeutic effect, such as, for
example, in early stages of HIV infection or in patients whose blood count shows a decrease in
CD4+ T cells (the causative virus of AIDS, Acquired Immune Deficiency Syndrome), in various
autoimmune disorders, or in some cases of genetic or acquired immune deficiencies. In AIDS
patients, the antibody may be administered to infected individuals, which have not yet
developed any symptoms of the disease, or in individuals at early stages of the HIV infection
process.
The dose of the antibody or composition to be administrated to a subject, in the context of
the present invention should be sufficient to effect a beneficial therapeutic response in the
subject over time, or to inhibit tumor growth. Thus, the antibody or composition may be
administered to a subject in an amount sufficient to alleviate, reduce, cure or at least partially
arrest the disease.
The dose will be determined by the activity of the therapeutic composition produced and
the condition of the subject, as well as the body weight or surface area of the subject to be
treated. The size of the dose and the dosing regiment also will be determined by the existence,
nature, and extent of any adverse side effects that accompany the administration of a particular
therapeutic composition in a particular subject. la determining the effective amount of the
therapeutic composition to be administered, the physician needs to evaluate circulating plasma
levels, toxicity, and progression of the disease.
Having now generally described the invention, the same will be more readily understood
through reference to the following examples, which are provided by way of illustration and are
not intended to be limiting of the present invention.
EXAMPLES
Example 1
Sequence analysis of the mouse BAT-1 kappa light chain variable region (Vk)
The DNA and amino acid sequences of the BAT-1 Vk region is shown in FIG. 1. The
amino acid sequences were compared with other mouse variable regions and also with the
consensus sequences of the subgroups that the variable regions were subdivided into in the
Kabat database (Kabat et al., ibid). From this analysis the BAT-1 Vk region was found to most
closely match the consensus sequences of both mouse kappa subgroup IV (Identity = 88.38%;
Similarity = 92.45) and mouse kappa subgroup VI (Identity = 87.74%; Similarity = 89.62).
When only the FRs of the BAT- 1 kappa light chain variable region (i.e. without the amino acids
in the CDRs) were compared to mouse subgroups IV and VI, percentage identity increased to
exactly 90.00% for both, while percentage similarity rose to 92.50%, again for both consensus
sequences. However, despite the close similarities to both Kabat subgroups, it was decided that
the murine BAT-1 Vk region should be classed as mouse subgroup VI.
The reason for the selection of mouse subgroup VI was related to the canonical classes of
the hypervariable loops of the BAT-1 Vk region, as defined by Chothia and his co-workers
(Chothia et al., J. Mol. Biol. 196:901, 1987; Nature 34:877, 1989; J. Mol. Biol. 227:799, 1992;
Tramontano et al., ibid). According to Chothia, each of the CDRs: CDR1 (L1), CDR2 (L2) and
CDR3 (L3), were canonical class 1 (FIG. 2). Crucially, the 10 amino acid canonical class 1 L1
hypervariable loop was only seen in mouse Vk regions which fitted Kabat subgroup VI.
Most restrictive canonical classes for the CDR related loops structures have more recently
been defined by Martin and Thornton (Martin et al, ibid) and these too are described in FIG. 2.
The utility of these new canonical class definitions lies in their stringency, which in turn is
related to the presence of a greater number of so-called framework canonical residues in each
class. The importance of these "extra", potentially key, residues was later considered when
designing the humanized BAT-1 antibody. Loops LI and L2 were easily assigned to Martins
canonical classes 1/10A and 1/7A, respectively, however, the L3 loop did not perfectly match
any of the classes available to it. The class that it most closely matched was class 1/9A,
however, to fit this class there had to be residue at position 28 in the Vk region of BAT-1, which
is not actually present. The closest mouse kappa light chain variable region germline gene to
BAT-1 Vk was H4, which also contained a 10 amino acid LI loop (Table 1). Only 12
mismatches were found between the H4 germline sequence and the BAT-1 Vk region. The
majority of these mismatches were positioned in the CDRs with only four differences located in
the FRs. Most of these mismatches were highly conservative changes, except for the cysteine at
position 72 (Kabat numbering) in FR3. Its location immediately adjacent to an important
canonical residue (position 71) suggested that the cysteine may have a key role in antigen
binding. Nevertheless, taken together, the above example clearly suggested that the BAT-1
sequence was typical of a mouse Vk variable region.
Example 2
Sequence analysis of the mouse BAT-1 heavy chain variable region
The DNA and amino acid sequences of the BAT-1 Vh region is shown in FIG. 3. An
analysis similar to that given in Example 1 was conducted for the BAT-1 Vh region which
determined that it exhibited the closest match to the consensus seance of the mouse heavy
chain miscellaneous subgroup in the Kabat database (Kabat et al., IDID). Identity between the
mouse heavy chain variable region amino acid sequence of mBAT-1 and the consensus
sequences of the miscellaneous subgroup was measured at 60.64% while the similarity was
calculated to be 69.23%, with the next closest Kabat subgroup consensus sequences being
subgroup IIa (Identity = 59.83%; Similarity = 66.67%). However, when, only the FRs of the
BAT-1 Vh region was compared to mouse subgroup IIa. percentage identity decreased to
54.02% while the similarity dropped to 62.06%. Conversely, the same comparisons carried out
against the mouse miscellaneous subgroup found the FRs of the BAT-1 VH region exhibited a
65.52% identity and a 74.71% similarity.
When the canonical classes of the hypervariable loops of the BAT-1 VH region, as defined
by Chothia and his co-workers, were analyzed (FIG. 4) the CDR1 and CDR2 loops (HI)
matched Chothia canonical class 1 loops. However, no class was assigned to the CDR3 loop
structure (H3) due to the wide range of size and amino acid make-up that H3 loops can display.
Using the more stringent canonical classes for CDR loop structures defined by Martin and
Thornton (Martin et al., ibid) it was a straight forward matter to determine that the HI loop
matched Martin canonical class 1/10A. However, for the H2 loop it was more difficult to assign
class, although the closest Martin canonical class was Class 2/10A. Unfortunately, since the
amino acid Asp53 in the H2 loop did not match the expected residues for this position (i.e. Ala,
Gly, Tyr, Ser, Lys, Thr or Asn), the match was also not perfect.
The closest mouse heavy chain variable region germline gene to mBAT-1 VH identified was
VMS2/VGK4 (Table 2). Thus the above example clearly suggested that the mBAT-1 sequence
was typical of a mouse Vh variable region.
1 No. of identical residues to the BAT sequence.
2 A dot [.] refers to a match between BAT Vh and the mouse germline Vh and a line [-] refers to
the absence of amino acid
Example 3
Design of the humanized BAT-1 Vk antibody variants
The first step in the design of the humanized variable regions of the BAT-1 antibody was
the selection of the human kappa light chain variable region that would serve as the basis of the
humanized BAT-1 Vk region. As an aid to this process the BAT-1 Vk region was initially
compared to the consensus sequences of the four human kappa light chain variable region
subgroups as defined by Kabat and his coworkers (Kabat et al., ibid).
The mouse BAT-1 light chain variable region was most similar to the consensus sequences
of human kappa light chain subgroup I and human kappa light chain subgroup III. In the case of
human kappa light chain subgroup I the mouse BAT-1 Vk region displayed a 63.21% identity
over the whole variable region and a 70.00% identity within the FRs alone. When measured
with respect to similarity, these values increased to 71.70% overall and 80.00% within the FRs
alone. In the case of human kappa light chain subgroup III the mouse BAT-1 Vk region
displayed a 65.09% identity over the whole variable region and a 68.75% identity within the
FRs alone. When measured with respect to similarity, these values increased to 74.53% overall
and 80.00% within the FRs alone. Consequently, it generally appeared to match well a broad
range of human kappa light chain variable region sequences, however, with respect to FRs in
particular, it was marginally more identical to those found within human kappa light chain
subgroup I.
The mouse BAT-1 Vk region was then compared to all the recorded examples of
individual sequences of human variable regions publicly available. Table 3 shows the best
fifteen matches to the mouse BAT-1 Vk region which were identified through this analysis.
Overall, the search algorithm selected the human Vk region from antibody TEL9 (Marks et al.,
J. Mol. Biol. 222:581, 1991) as the closest match to the mouse BAT-1 Vk region (Table 4). This
human sequence had an overall identity to the BAT-1 Vk region of 67.93% overall and 72.50%
within the FRs alone. When measured with respect to similarity, these values increased to
77.36% overall and 82.50% within the FRs alone. Consequently, the TEL9 kappa light chain
variable region FR was selected as the human acceptor sequence for the humanization of the
BAT-1 antibody kappa light chain variable region. This then became the basis of the first
humanized version of the BAT-1 kappa light chain (BATRka), which essentially comprised the
CDRs of the BAT-1 Vk region and the FRs of the TEL9 Vk region.
The next step in the design process was to study the amino acid sequences of the human
acceptor TEL9 VK region FRs to determine if any of these amino acid residues were likely to
adversely influence binding to antigen, either directly through interactions with antigen, or
indirectly by altering the conformation or orientation of the CDR loops. This was a difficult
process which was only made possible through the availability of a model of the BAT-1 variable
regions i.e. both the Vk and Vh regions. The modeling procedure will be given in detail in
Example 5. Nevertheless, any amino acid in the mouse BAT-1 FRs which did appear to affect
antigen binding were then considered for conservation in the humanized BAT-1 antibody. In
deciding which murine residues to conserve the following points were addressed:
2 A dot [.] refers to a match between BAT Vk and the mouse gennline Vk, a line [-] refers to the
absence of amino acid, underlined residues in the human Vk sequences differ from their closest
human Vk gene
3S/C refers to amino acids positioned within 5A of a CDR on the Surface or Core of Fv and s/c to
amino acids positioned further away than 5 A of a CDR on the surface or core of Fv
4 v refers to Vernier residues (Footer et al., J. Mol. Biol. 224:487, 1992) located in the FRs
1ID - percentage identity of the human Vk sequences to the tnurine BAT Vk region 2All -
number of identical residues in the whole of the human Vk region when compared to the
whole of the murine BAT Vk region
3Surface (FR Surface) - number of identical (FR) residues on the surface
4Core (FR Core) - number of identical residues within the (FR) core of the Fv domain
5CDR/FR - number of identical residues within the CDRs or the FRs;
FR Near CDR - represents the number of identical residues amongst the FR amino acids
within 5A of a CDR;
Vernier - number of identical residues amongst the 14 Vernier amino acids (Foote et al.,
ibid);
8 Vk (J Chain) - number of identical residues within the Vk (J Chain) gene
9L1 to L3 Size - number of residues in each CDR
10L1 to L3 Class - Canonical class of the CDR according to Martin & Thornton (Martin et al.,
ibid)
a. It was of great importance that the canonical structures for the hypervariable loops
(Chothia et al., 1987, 1989, 1992 ibid; Tramontano et al., ibid) were conserved.
Consequently, it was crucial to conserve in the humanized BAT-1 variable regions all the
mouse FR residues that were part of these canonical structures.
b. The sequences of the mBAT-1 antibody variable regions were compared to similar
sequences from other mouse antibodies to identify unusual or rare residues - which may
have indicated an important role in antigen binding. This was then investigated using the
model of the BAT-1 variable region genes.
c. A direct analysis of the model was alsol made to try and predict whether any of the other
mouse FR residues not present in the Humanized FRs could influence antigen binding in
some way.
d. Comparisons of the individual human acceptor sequences for the kappa light and heavy
chain variable regions to the consensus sequence of human variable regions subgroups to
which the acceptor sequences belonged were also made. The identification of any
idiosyncratic amino acids in the human donor sequences was important as these could
have adversely affected antigen binding.
e. Since the human light and heavy chain variable regions selected would be derived from
two different human antibodies (see Example 4 for the selection of the human Vh acceptor
sequence), a careful analysis of the interdomain packing residues of both the donor and
acceptor kappa light variable regions should be carried out. This was because any miss-
packing in this region could have had a dramatic affect upon antigen binding, irrespective
of the conformation of the CDR loop structures of the humanized BAT-1 antibody,
f. By following this design process, a number of amino acids in the rrmrine BAT-1 Vk FRs
were identified for conservation in the second version (BATRkb) of the humanized BAT-1
antibody (Table 5). Table 5 provides alignment of amino acid sequences leading to the
design of the first (BATRka) and second (BATRkb) reshaped human versions of the BAT-
1 antibody kappa light chain variable region. There were 21 amino acid differences
between the FRs of the donor mouse BAT-1 Vk region and the acceptor human TEL9 Vk
region. However, there were only five residues in the humanized FRs where it was
considered necessary to change the amino acid present in the human FRs to the amino acid
present in the original mouse FRs.
The Vk region amino acids, located at the Vk/Vh interface as defined by Chothia and
colleagues (Chothia et al., J. Mol. Biol. 186:651, 1985), were checked for unusual or rare
residues. From this analysis, the only residue position that raised any level of concern was the
Phe at position 36 (Phe36) in FR2. Tyr (as found in TEL9) was normally seen at this position,
however, in mBAT-1 Phe was present, In addition, position 36 was a recognized position for a
Vernier amino acid (Foote et al., ibid). Vernier residues were thought to be important for
maintaining CDR loop conformation. Moreover, Phe was not commonly seen in Kabat mouse
subgroup VI (21/153) while Tyr was very commonly seen in both mouse subgroup VI (131/153) and
human subgroup I (66/74) (Kabat et al., ibid). Consequently, a Tyr36Phe change was thought to
be appropriate, both to mimic the interdomain packing found in BAT-1, between the two
heterologous human acceptor variable regions, and also to maintain CDR loop conformation.
A second change was also decided upon at position 47 in FR2. The highly conserved Leu
found in the human TEL9 kappa light chain variable region was changed to a Trp, as found in
the mouse BAT-1 kappa light chain variable region. Position 47 was another recognized Vernier
residue position and was also located near the VH interface according to the molecular model, In
particular, it was close to Ala55 in H2 and may have been interacting with it. Therefore,
although Trp was never seen at this core residue position in human VH sequences, it was felt
prudent to conserve it in BATRkb by making the Leu47Trp modification.
The third FR change introduced into BATRkb was located at position 7-1, which as well as
being identified as a Vernier residue position (Foote et al, ibid), was also recognized as being
one of the important canonical residue positions for the L1 loop stmcture. These canonical
residues were defined by Chothia and his co-workers (Chothia et al.., 1987, 1989, 1992 ibid;
Tramontano et al., ibid) as being vital for the conservation of the CDR loop structure. Many of
the canonical amino acids were located within the CDRs, however, a number (such as 71Tyr)
were also positioned within the FRs. Although the amino acid change was conservative, the
Phe71Tyr change was considered critical for the successful huinanization of the BAT-1 kappa
light chain.
Other versions of the humanized Vk region are:
BATRkc: Cys and Ser are similar in size and character, and from the model both amino
acids at position 72 in FR3 appeared to be reasonably buried and pointing away from the LI
loop. However, in the case of the Cys amino acid the sulphur side-chain is exposed, according to
the model, whereas according to the Kabat database (Kabat et al., ibid) the presence of Cys at
this position is a unique event and Ser is commonly seen at this position (421/1234). Consequently,
BATRkc contained the changes at Tyr36Phe, Leu47Trp and Phe71Tyr (as in BATRkb) plus the
Ser72Cys modification to the Vk FRs residues of the acceptor TEL9 antibody.
BATRko: Evidence from the murine BAT-1 Fv model suggests that the surface exposed
70Ser is a residue which may interact with the LI loop. In the human TEL9 kappa light chain
the amino acid at this position is Asp, which is larger than Ser and positively charged. Ser is
never seen at this position in human Vk regions (Asp being by far the most common amino
acid). The proximity to the L1 loop and the surface exposed nature of 70Ser tentatively
suggested that it may be either interacting with L1 or even the antigen directly. Consequently, it
was decided to make the Asp70Ser change in BATRkd, which was otherwise identical to
BATRkc.
A description of the amino acid sequences of all the humanized BAT-1 antibody Vk
region variants proposed above is given in FIG. 5.
Although potential N-linked glycosylation sites i.e. Asn-Xaa-(Ser/Thr)-Xaa (Gavel et al.,
Protein Eng. 3:43, 1990) were searched for in both the donor mouse and acceptor human Vk
regions, as well as the humanized constructs themselves, none were identified.
Example 4
Design of the humanized BAT-1 \'h antibody variants
Again, the first step in the design of the humanized Vh region of the mouse BAT-1
antibody was the selection of the acceptor human heavy chain variable region that would serve
as the basis of the humanized BAT-1 VH region. When the mBAT-1 VH region was initially
compared to the consensus sequences of the three human heavy chain variable region subgroups
it was found to be most similar to the consensus sequence for human heavy chain subgroup I
with a 61.54% identity overall and a 67.82% identity between the FRs alone. When measured
with respect to similarity, these values also increased to 70.09% overall and 77.01% within the
FRs alone.
The mouse BAT-1 Vh region was then compared to all the recorded examples of
individual sequences of human variable regions publicly available. Tables 6 and 7 show the best
fifteen matches to the mouse BAT-1 VH region which were identified through this analysis.
Overall, the search algorithm selected the human Vh region from antibody hsighvl295 (Fang et
al., J. Exp. Med. 179:1445, 1994) as the closest match to the mouse BAT-1 VH region. This
human VH region had an overall identity to the BAT-1 VH region of 69.23% (Table 7), a value
which increased to 74.71% when the FRs alone were compared. When measured with respect to
similarity, these values increased to 75.21% overall and 79.31% within the FRs alone. This
human FR thus became the basis of the humanized version of the BAT-1 heavy chain.
ID - percentage identity of the human Vh sequences to the murine BAT Vh region 2All -
number of identical residues in the whole of the human Vh region when compared to the
whole of the murine BAT Vh region
3Surface (FR Surface) - number of identical (FR) residues on the surface
5 4Core (FR Core) - number of identical residues within the (FR) core of the Fv domain
5CDR/FR - number of identical residues within the CDRs or the FRs;
6FR Near CDR - represents the number of identical residues amongst the FR amino acids
within 5A of a CDR;
Vernier - number of identical residues amongst the 14 Vernier amino acids (Foote et al.,
10 ibid);
8Vh (J Chain) - number of identical residues within the Vh (J Chain) gene
9L1 to L3 Size - number of residues in each CDR
10L1 to L3 Class - Canonical class of the CDR according to Martin & Thornton (Martin et al.,
ibid)
15
The next step in the design process was to study the amino acid sequences of the human
acceptor hsighvl295 Vh region FRs to determine if any of these amino acid residues were likely
to adversely influence binding to antigen. Once again, the molecular models built by OML (see
Example 5) were crucial to this design process, from which a number of amino acids in the
marine BAT-1 Vh region FRs were identified for conservation in the first (BATRHa) and
subsequent versions of the humanized BAT-1 antibody (Table S). There were 22 amino acid
differences between the FRs of the donor mouse BAT-1 and the acceptor human hsighvl295 Vh
regions and up to nine murine residues were considered for conservation in the humanized FRs.
BATRHa therefore consisted of the CDRs of the mouse BAT-1 antibody VH region
genetically inserted into the FRs of the human hsighvl295 antibody VH region. This was the
CDR-grafted version of the Vh region of the humanized BAT-1 antibody and contained no FR
amino acid changes whatsoever.
In BATRHb, the amino acids at positions 28 and 30 in FR1 of the mouse BAT-1 sequence
(i.e. Thr and Thr, respectively) replaced the corresponding human hsighv 1295 amino acids (i.e.
Ser, and Ser, respectively) in the humanized BAT-1 heavy chain variable region. This was done
because they represented some of the canonical residues important for the HI hypervariable
loop conformation (Chotbia et al, 1992 ibid). Canonical residues were considered critical for
the correct orientation and structure of hypervariable loops and were generally always conserved
in a humanized variable region. Moreover, residue positions 27-30 were considered part of the
HI loop itself and so were even more critical to the correct conformation and orientation of this
loop - justifying their conservation even more strongly. Thus, these two residue positions
represented the sum of the changes made to the FRs of the human hsighvl295 sequence in
BATRHb.
The next step in the design process was to study the amino acid sequences of the human
acceptor hsighvl295 Vh region FRs to determine if any of these amino acid residues were likely
to adversely influence binding to antigen. Once again, the molecular models built by OML (see
Example 5) were crucial to this design process, from which a number of amino acids in the
murine BAT-1 Vh region FRs were identified for conservation in the first (BATRHA) and
subsequent versions of the humanized BAT-1 antibody (Table 8). There were 22 amino acid
differences between the FRs of the donor mouse BAT-1 and the acceptor human hsighvl295 Vh
regions and up to nine murine residues were considered for conservation in the humanized FRs.
BATRHa therefore consisted of the CDRs of the mouse BAT-1 antibody Vh region
genetically inserted into the FRs of the human hsighvl295 antibody VH region. This was the
CDR-grafted version of the VH region of the humanized BAT-1 antibody and contained no FR
amino acid changes whatsoever.
In BATRHb, the amino acids at positions 28 and 30 in FR1 of the mouse BAT-1 sequence
(i.e. Thr and Thr, respectively) replaced the corresponding human hsighvl295 amino acids (i.e.
Ser, and Ser, respectively) in the humanized BAT-1 heavy chain variable region. This was done
because they represented some of the canonical residues important for the HI hypervariable
loop conformation (Chothia et al., 1992 ibid). Canonical residues were: considered critical for
the correct orientation and structure of hypervariable loops and were generally always conserved
in a humanized variable region. Moreover, residue positions 27-30 were considered part of the
H1 loop itself and so were even more critical to the correct conformation and orientation of this
loop - justifying their conservation even more strongly. Thus, these two residue positions
represented the sum of the changes made to the FRs of the human hsighv 1295 sequence in
BATRHB.
The third version of the humanized BAT-1 Vh region (BATRHc) incorporated all the
substitutions made in BATRHb. and, in addition, contained a further three muiine amino acids,
which were inserted into the human FRs in place of the corresponding human residues. The first
of these was the Asn amino acid located at position 76 in FR3. According to the molecular
model of the BAT-1 Fv region, the Asn residue was close to CDR H1 and may have been
supporting the loop structure. In addition, in the mouse BAT-1 VH region, the Asn was surface
exposed and larger than the Ser in the human hsighvl295 FRs. Consequently, a Ser76Asn
substitution was made to the FR.
A further change was made to the amino acid at position 94 in FR3 of the VH region, a
residue position which had been previously identified by Chothia et al. (Chothia et al., 1992
ibid) as well as by Martin and Thornton (Martin et al.., ibid), as .important for H3 loop
conformation. Moreover, the molecular model indicated that: the Arg94 could form a salt bridge
with AsplOl in CDR H3, stabilizing the loop structure. Consequently, the Arg in the mouse
replaced the Lys in the human at this residue position. A final modification was also made at
position 93 in FR3 where the human Ala was replaced by the murine Val amino acid. This
residue was considered a packing residue, as defined by Chothia (Chothia et al., 19S5 ibid),
important for the correct packing of the Vk and Vh regions. In addition, this was identified as a
Vender residue position, and therefore important for maintaining CDR loop conformation, a
classification confirmed by an analysis of the molecular model. Taken together, all the data and
molecular analysis suggested that it was appropriate to conserve these three murine residues in
the humanized VH region of BATRHC, i.e. Ser76Asn, Ala93Val and Lys94Arg.
The construction of the next two humanized variants of the BAT-1 VH region depended
upon the binding affinity of these first three humanized versions i.e. BATRHa, BATRHb and
BATRHC. If all three failed to display an adequate level of binding, then versions BATRHd and
BATRHe would be synthesized and tested.
Version D of the humanized BAT-1 VH region (BATRHD) incorporated all the
substitutions made in BATRHe and, in addition, contained one further mouse amino acid
located at position 2 in FR1. This location was denned as both a canonical (Martin et al, ibid)
and Vernier (Foote et al., ibid) residue position. In addition, from the model of the BAT-1
variable region, the murine Ile amino acid was close to Tyr27 in FR1, which is itself part of the
HI loop structure. Conversely, the murine Ile and human Val amino acids, at this location in the
mouse and human FRs, were similar in character and only slightly different in size, i.e. Ile has
an extra methyl group. Therefore, it was decided to make the Val2Ile change only at this stage
of the humanization procedure and incorporate the mutation into version BATRHd-
The final version of the humanized BAT-1 heavy chain variable region (BATRHE)
incorporated all the mouse FR substitutions made in BATRHd along with three additional amino
acid changes at positions 38 (FR2), 46 (FR2) and 68 (FR3).
The Arg38Lys modification was made because the model suggested that the Arg, deeply
buried in the core of the Vh region, was close to Phe63 in CDR H2. However, this was not a
previously identified canonical or Vernier residue position. In addition, Arg and Lys are
relatively similar in structure, although Arg is builder, and so the significance of any amino acid
change was hard to judge. Consequently, this was considered as only a tentative possibility and
the substitution was only going to be made if the binding affinity of the humanized BAT-1
antibody was found to be poor. The same rationale was also behind the selection of the
Ghi46Lys modification. The Lys amino acid was half-buried, according to the molecular model,
but close to Glu62 and Phe63 in CDR H2. There was a faint possibility that the larger, charges
Lys46 residue could interact with the antigen directly, therefore it was conserved in BATRHe.
The case for preserving the murine 68Ala amino acid was related to its proximity to CDR H2,
particularly to residue Tyr59 in the H2 loop, and to the chance of it therefore influencing loop
structure. The Ala was unlikely to be important due to its small size, however the larger Val,
found in the human hsighvl295 FRs could have adversely affected H2 loop structure, and so
was replaced with the murine Ala residue.
A description of the amino acid sequences of all the humanized Vh region variants
proposed above is given in FIG. 6.
Although potential N-linked glycosylation sites i.e. Asn-Xaa-(Sex/Thr)-Xaa (Gavel et al.,
ibid) were searched for in both the donor mouse and acceptor human VH regions, as well as the
humanized constructs themselves, none were identified.
Example 5
Molecular modeling of the murine and humanized BAT-1 Fv domain
To assist the design of the humanized variable regions of the BAT-1 antibody, a molecular
model of the variable regions of both the murine and the humanized antibodies were built. The
modeling of these structures was achieved using both the established methods of modeling by
homology and ab initio techniques. This was done using AbM molecular modeling package,
which was supplied and utilized by Oxfored Molecular Limited (OML). Antibody X-ray
crystallographic structures from the Brookhaven database available were formatted to allow
them to be used for modeling with AbM.
The FRs of the BAT-1 variable regions were modeled on FRs from similar, structurally
solved immunoglobulin. variable regions. While identical amino acid side-chains were kept in
their original orientation, mismatched side-chains were substituted as in the original BAT-1 Fv
region. The backbone atoms of the FAB17-IA Vk region were used for the model of the BAT-1
Vk region, while the FRs of the 409.5.3 Vh region were used to model the BAT-1 Vh region
(Brookhaven PDB codes lfor and liai, respectively). These sequences both represented good
matches for the variable region sequences of murine BAT-1 antibody, and their humanized
variants. The identities for the mBAT-1 and humanized sequences ranged from 73% to 92% for
Vk region sequences and between 65% and 79% for VH region sequences. Testing of AbM with
known structures has shown that FR backbone homology is an important factor in the quality of
any model, since the use of FR structures that poorly match a sequence being modeled can
significantly and adversely affect the position and orientation of the CDR loop structure.
For the backbone structure of the L1 loop, the loop conformations of the murine BAT-1
Vk region and the humanized BATRkb sequence (FIG. 5) were taken from canonical classes
used by AbM. These canonical classes are based on those described by Chothia and his
colleagues, but they have been modified to take into consideration structures that have become
available since the original articles were published (Chothia et al., 1987, 1989, 1992 ibid;
Tramontano et al., ibid). Testing the performance of AbM predictions for known loop structures
has shown that CDR loops which are created in this way are usually modeled very accurately,
i.e. to within 1-1.5A RMS deviation. For the Vk region sequence BATRka, the substitution of
Phe for Tyr at position 71 (in FR3) meant that it no longer fitted the canonical class (Class 1)
seen in the murine Vk region and the humanized BATRkb Vk region. Tyr71 had an important
role in the conformation of the L1 loop, however, analysis of the modeled structures suggested
that it was the packing of the L1 loop against the aromatic ring of Tyr which was the key feature
of the residue. Thus, there was reason to believe that Phe could also perform this function. In
addition, from the models there did not seem to be any strong interactions with the hydroxyl
group of Tyr71. Consequently, there was a possibility that the substitution of Tyr with Phe
could well have had no affect the actual conformation of the L1 loop.
For the backbone structures of CDRs L2, L3, H1 and H2, conformations for all the models
were taken from canonical classes defined by AbM without modification.
The H3 loop in the BAT-1 VH region was eight residues long, so two methods were used
for predicting the H3 loop structure. A database search for the backbone conformations was
used for both methods, but in addition, the conformation of the central five residues in the model
were searched more thoroughly using a CONGEN search (Bruccoleri, Ibid). Although this took
longer to compute, it reassuringly produced a conformation which was very similar to those
identified from the database search.
After adjusting the whole of the model for obvious steric clashes it was finally subjected to
energy minirmzation, as implemented in MACROMODEL, both to relieve unfavorable atomic
contacts and to optimize van der Waals and electrostatic interactions.
Example 6
Construction of humanized BAT-1 light chain variants
As with all examples, a strict PCR-cloning and sequencing protocol was followed. This
was done to minimize the possibility of introducing errors into the humanized versions. The
construction of the humanized BAT-1 kappa light chain variable region genes (i.e. BATRka,
BATRkb, and BATRkd) produced an approximately 425 bp product which was then subcloned
in pCR2.1™. The PCR reactions were set up using the primers described in Tables 9 and 10.
Putative positive transformants were identified using tie PCR-screening assay, restriction
digest and then ds-DNA sequenced. The humanized Vk genes (FIGS. 7-9; SEQ ID NOS. 15,16 and
18) were then sub cloned into expression plasmids.
The light chain pKN110 construct included Ampicillin and Neomycin resistance genes.
The humanized Vk gene variants of BAT-1 (i.e. BATRka, BATRkb and BATRkd) were
inserted between the HCMV Immediate Early Promoter and the genomic human kappa constant
region resulting in the following expression vectors: pKN110-BATRka, pKN110-BATRKB and
pKN110-BATRkd, respectively (see FIG. 10 for a representative pKN110-BATRKD vector).
The BAT-1 light chain expression cassette inserted into an expression vector included a
DNA fragment encoding a mouse immunoglobulin signal peptide sequence, Kozak sequence
and a signal sequence nitron which was added to both sides of the humanized Vk gene variants
of BAT-1 (FIG. 11). This cassette was inserted between the HCMV Immediate Early Promoter
and the genomio human kappa constant region. The complete light chain expression vector also
included a BGH polyA transcription terminator and a Neo/G418 selection marker. All constructs
were restriction enzyme digested and ds-DNA sequenced to confirm the presence of the correct
insert.
Example 7
Construction of humanized BAT-! heavy chain variants
The construction of the various versions of the reshaped human BAT-1 heavy chain
variable region genes (i.e. BATRHA, BATRHb, BATRH'c) produced an approximately 450 bp
product which was then subcloned into pCR2.1™. The PCR reactions were set up using the
primers described in Tables 11 and 12.
Putative positive transformants were again identified in a PCR. screen and then ds-DNA
sequenced. The humanized Vh genes (SEQ ID NOS. 20 - 22) were then subcloned
into expression vectors.
The heavy chain pG1D110 construct included Ampicillin resistance gene and the hamster
dhfr as the selectable marker. The humanized Vh gene variants of BAT-1 were inserted between
the HCMV Immediate Early Promoter and the genomic human IgG1 constant region resulting in
the following expression vectors: pG1D110-BATRHA, pGlD110-BATRHB, pGlDHO-
BATRHc (see FIG. 15 for a representative pGlD110.BAT-l.RHG vector).
The BAT-1 heavy chain expression cassette inserted into an expression vector which
included a DNA fragment encoding a mouse itnmunoglolbulin signal peptide sequence, Kozak
sequence and a signal sequence intron which was added to both sides of the humanized Vk gene
variants of BAT-1 (FIG. 16). This cassette was inserted between the HCMV Immediate Early
Promoter and the genomic human IgG1 constant region. The complete light chain expression
vector also included a BGH polyA transcription terminator and a dhfr selection marker.
The resulting expression vectors were restriction enzyme digested to confirm the presence
of the correct insert.
Example 8
Construction of BAT-1 RHc/Rkd ?1 complete antibody in a single expression vector
in order to maximize the achievable expression levels for the BAT-1 yl antibody it was
decided to remove an intron from the pGlD110.BAT-1.RHc construct (described in Example 7,
see FIG. 15) before making the BAT-1 yl single vector construct. This procedure was carried
out as follows.
pGlD200 is another yl immunoglobulin heavy chain mammalian expression vector
(AERES Biomedical; FIG. 17). This vector is a VH:CH ?1 intron minus version of the pG1D110
vector (i.e. it does not have the 71bp intron at the VH:CH junction).
In order to convert the pG1D110.BAT-l.RHc construct into a construct, a BstER fragment
(219bp) was excised from the pGlD200 vector and gel purified using a Qiagen gel
extraction/purification kit. This fragment contained the intron minus Vh:Ch junction.
The pGlD110.BAT-l.RHc construct (FIG. 15) was also restriction digested with BstER,
releasing a 290bp fragment which contained the intron plus VH:CH junction. The remaining
vector fragment (~7207bp) was gel purified using a Qiagen gel extraction/ purification kit.
The intron minus BstEII fragment (219bp) from the pGlD200 vector digest was then
ligated into the ~7207bp BstER digested pGlD110.BAT-l.RHc vector. 2µ1 of ligated DNA was
transformed into DH5a cells (Stratagene) according to the manufacturers instructions. Plasmid
DNA was prepared from 10 colonies and each, plasmid DNA was analyzed for the presence of
the correct BstBII fragment by DNA sequence analysis.
Following identification of a perfect clone, the new nitron minus construct
(pGlD210.BAT-l.RHc) and the light chain construct pKN110.BAT.RkD (see FIG. 10) were
used to construct the pG1KD210.BAT-1.RHc/RKD single expression vector (SEQ ID NO. 93).
The component of this pG1KD210.BAT-1RHc/RKD single expression vector within SEQ
ID NO 93 are localized as follows:
1. Nucleotide range: 1 to 2502 - pBE322 (pBR322 based sequence including the Amp-
resistance gene and Co1E1 origin plus the SV40 origin and crippled SV40 early
promoter)
2. Nucleotide range: 206 to 1067 - Amp (Ampicillin resistance gene)
3. Position: 1824-Co1E1
4. Nucleotide range: 2502 to 3227 - DHFR (Dihydrofolate reductase gene)
5. Nucleotide range: 3233 to 4074 - SV40 polyA (SV40 poly A sequence etc)
6. Nucleotide range: 4109 to 5649 - HCMVi (HCMVi promoter)
7. Nucleotide range: 5662 to 6067- BAT rKd
Reshaped BAT lcappa light chain variable region.
8. Nucleotide range: 6073 to 6720 - HuK (cDNA copy of human kappa constant region
(Krn(3)) gene)
9. Nucleotide range: 6726 to 6943 - spaC2 Artificial spaC2 termination sequence
10. Nucleotide range: 6949 to 8489- HCMVi (HCMVi promoter )
11.12. Nucleotide range: 8502 to 8923 - BAT rHc
Reshaped BAT heavy chain variable region
13. Nucleotide range : 8924 to 10297 - HG1 (Human gamma-1 constant regions
preceded by a 60bp natron and followed by the 'Amie' termination sequence)
The BAT-1 kappa light chain expression cassette which contained the HCMVi promoter, the
BAT-1 kappa light chain variable region gene, and the kappa light chain constant region gene,
was restriction enzyme digested (EcdBI /SpeI) out of the pKN110.BAT-1.Rkd construct and
subsequently ligated into the pGlD210.BAT-l.RHc construct via the unique EcoRI and SpeI
restriction sites. This ligation resulted in the construction of the single expression vector
pGlKD210.BAT-1.RHc/RKD, containing both the heavy and kappa light chains of the BAT-1
humanized antibody RHc/Rkd (FIG. 18). 2µ1 of ligated DNA was transformed into DH5a cells
(Stratagene) according to the manufacturers instructions. Mini prep DNA. was prepared from ten
colonies and each plasmid DNA was analyzed for the presence of the correct single expression
construct by restriction digesi analysis. One clone of a correct single expression construct was
chosen for the transient expression of the BAT-1 gamma-1 antibody in COS cells as will be
illustrated in Example 11.
Example 9
Construction of the BAT-1.BHc/Rkd gamma-1 (?1) complete antibody variant in a single
expression vector
The BATRHc heavy chain variable region was transferred to the combined (single)
expression vector as an Xhol to Hind111 fragment. The BATRkd light chain variable region
was transferred to the combined (single) expression vector as ssiXbal to BamBI fragment. The
internal Xbal site in the light chain gene was removed without changing the amino acid
sequence. The sequences of the BAT-1.RKr/BAT-1.RHc heavy and light chain variable regions
in this vector were confirmed. The vector includes genomic human IgG1 and Kappa constant
regions. Both heavy and light chain genes were placed under the control of the HCMV
Immediate Early promoter. The vector includes a mouse dhfr gene as the selectable marker (see
FIG. 19). The same Kozak sequence, signal peptide sequence and intion were added as for the
two vector expression system (see Examples 6 and 7).
Example 10
Construction of the BAT-1 gamma-4 (?4) PG4KD110.BAT-1. RHc/RKd in a single vector
The first step in the construction of the BAT-1 yA single expression vector construct was
the cloning of the modified BAT-1.RHC gene out of the pGlD110.BA.T-1.RHc construct (FIG.
14) by BamHI and HindIII restriction digest, and ligation of tins 430bp fragment into the
gamma-4 immunoglobulin heavy chain expression vector pG4D110, again via BamHI and
HindIII. restriction sites.
2µl of ligated DNA was transformed into DH5a cells (Stratagene) according to the
manufacturers instructions. Plasmid DNA was prepared from 10 colonies and each plasmid
DNA was analyzed for the presence of the correct BAT-1.RHC BamHI/HindIII fragment by
DNA sequence analysis.
Following identification of a perfect clone, the new gamma-4 construct (pG4D110.BAT-
1.RHc) and the light chain construct pKN110.BAT-1.RKD (FIG. 10) were used to construct the
pG4KD110.BAT-1 ,HRc/Rkd single expression vector in the following way.
The BAT-1 kappa light chain expression cassette which contained the HCMVi promoter,
the BAT-1 kappa light chain variable region gene, and the kappa light chain constant region
gene, was restriction enzyme digested (EcoRI/SpeI) out of the pKN110.BAT-1.Rkd construct
and subsequently ligated into pG4D110.BAT-l.RHc construct via the unique EcoRI and SpeI
restriction sites. This ligation resulted in the construction of a single expression vector construct
pG4KD110.BAT-1.RHc/Rkd, containing both the heavy and kappa light chains of the BAT-1
humanized antibody RHc/Rkd variant. 2µl of ligated DNA was transformed into DH5a cells
(Stratagene) according to the manufacturers instructions. Mini prep DNA was prepared from ten
colonies and each plasmid DNA was analyzed for the presence of the correct single expression
vector construct by restriction digest analysis. The correct single expression vector construct
digested with BamHI and with HindIII released a 2864bp fragment and the HindIII digest
released a 2840bp fragment. One clone was chosen for the transient expression of the BAT-1
gamma-4 antibody in COS cells.
Example 11
Co-transfection of humanized BAT-1 light and heavy chain vectors, and transient
expression of the humanized BAT-1 variants in COS7 cells
The humanized BAT-1 heavy (pGlDllO) and light (pKNUO; Example 7) chain
expression vectors were co-transfected, at various combinations, into COS7 cells and after 72 hr
incubation, the medium was collected, spun to remove cell debris, filtered and analyzed by
ELISA for humanized antibody production. The concentration of humanized antibody in the
COS7 cell supematants varied with each combination of reshaped human BAT-1 antibody
constructs that were tested (Table 13). For example, version BATRHb/BATRka expressed the
highest antibody levels (4800 ng/ml) whilst the BATRHb/BATRkd version was the poorest
expresser (357 ng/ml).
Example 12
Purification of the humanized BAT-1 variants from COS7 cells
Harvesting approximately 8 ml per co-transfection (see Example 11), a series of
transfections were carried out until in excess of 200 ml of COS7 supernatant had been collected.
The volume of this supernatant was reduced to 10 ml by passing the supernatant through a
stirred ultra-filtration cell with a PM30 filter membrane - which had a molecular weight cut-off
of 30 kDa.
The Immunopure©(A) IgG purification kit essentially comprised of a 2 ml column of
immobilized Protein A Sepharose column. The antibody was eluted from the column with 5 ml
of elution buffer, the eluate of which was collected in 1 ml fractions. The concentration of
0humanized BAT-1 antibody in each fraction was then assayed using ELISA methods. Table 13
describes the final concentrations of the Protein A purified antibody constructs collected. On
average the purification step increased the antibody concentration by approximately 150-fold.
Example 13
Analysis of Daudi cell binding to the humanized BAT-1 variants produced in COS7
cells
Using the Daudi cell ELISA iit was clear that the different versions of the Protein A
purified humanized BAT-1 antibody bound to Daudi cells to various degrees. FIGS. 20-23 show
typical examples for these binding experiments. Sigmoidal dose-response curves of Daudi cell
binding by the recombinant antibodies were also plotted and the hill slopes of these binding
curves were calculated. The combination of the hill slope data and the positions of the dose-
response curves relative to the chimeric antibody dose-response curves suggested a qualitative
hierarchy with respect to Daudi cell binding among the various humanized BAT-1 antibody
constructs tested (Table 14). At the top of this hierarchy was clearly construct
BATRHc/BATRkd, which exhibited a hill slope (i.e. 0.8818 ± 0.1107) very similar to its
chirneric BAT-1 antibody control (i.e. 0.8248 ± 0.1210) and closely tracked the dose-response
curve of the chimeric control. Although construct BATBHc/BATRkb displayed a steeper hill
slope (i.e. 0.6408 ± 0.1622) than the same chimeric BAT-1 antibody control (i.e. 0.8248 ±
0.1210), as calculated from the available binding data, the difference was no statistically
significant, hi addition, it is clear from FIG. 22 that the dose-response curve for this construct is
not as good as for the BATRHc/BATRkd construct and was therefore ranked second in the
binding hierarchy.
Conversely, construct BATRHa/BATRka clearly has the poorest binding characteristics of
all the humanized BAT-1 antibody constructs tested (Table 14) and so was ranked sixth in the
binding hierarchy. Although the calculated hill slope for this version (i.e. 1.2730 ± 0.2688) is
apparently better than the very similar humanized construct BATRHb/BATRka (i.e. 1.7710 ±
0.6461) this difference is again not statistically significant. In addition, it is clear from FIG. 21
that the CDR-grafted BATRHa/BATRka BAT-1 antibody is reaching its maximum binding
response at much lower level than the humanized construct BATRHb/BATRka - which was
ranked fifth in the binding hierarchy.
Constructs BATRHb/BATRkb (FIG. 20; ranked fourth) and BATRHb/BATRkd (FIG. 23;
ranked third) display intermediate levels of binding between these two sets of extremes. Again
these rankings were mainly based upon a subjective interpretation of the binding data available
and previous experience.
Example 14
Transient expression of the BAT-1 Rkd/RHc variant by co-transfection or by single
transfection of COS cells
The method of Kettleborough (Kettleborough et al., Eur. J. Immunol. 23:206, 1993) was
followed to transfect the mammalian expression constructs into COS cells. Briefly, the DNA
(10µg each of the kappa light chain expression construct pKN110.BAT-1.Rkd and the heavy
chain expression construct pGlD210.BAT-l.RHc, or 13µg of the single vector construct
pG1KD210.BAT-1.RHc/Rkd) was added to a 0.7 ml aliquot of 107 cells/ml in PBS and pulsed
at 1900 V, 25 µF capacitance using a Bio-Rad Gene Pulser apparatus. Following a 10 minute
recovery at room temperature, the electroporated cells were transferred to petri-dislies
containing 8 ml of DMEM containing 10% FCS and incubated for 72 hrs in 5%CO2 at 37°C.
After 72 hrs incubation, the medium was collected, spun to remove cell debris, and analyzed by
capture ELISA for antibody production. The co-transfections, with light chain expression
vector and heavy chain expression vector, and transfections with a single-vector expressing both
light and heavy chains, were carried out in triplicate. The results are presented in Table 15. The
results indicate that expression levels from the single vector are ~6 fold higher than the
expression levels observed for the co-transfections.
Example 15
Stable transfection of CHOdhfr- mammalian cells with the single vector pGlKD210.BAT-
1.RHc/Rkd and production of stable cell lines
CHOdhfr- cells were propagated in a non-selective media consisting of a-MEM with
ribonucleosides and deoxyribonucleosides, supplemented with 10% Fetal Clone II and 50µg/ml
Gentamicin. Aliquot, 0.7 ml, of 107 cells/ml in PBS was transfected with Bug of
pGlKD210.BAT-l.RHc/RKD at 1900 V, 25 µF capacitance using a Bio-Rad Gene Pulser. The
cells were allowed to recover for 10 minutes at RT before being transferred to 10 cm petri-
dishes in 8 ml of non-selective media and then incubated in 5% CO2 at 37°C for 48 hours.
Two days after transfection, the cells were trypsinized, spun down and resuspended in 150
ml of prewarmed selective media (a-MEM without ribonucleosides and deoxyribonucleosides,
supplemented with 10% dialyzed FBS and 50µg/ml Gentamicin, and containing either lOnM,
50nM, 100nM or 500nM Methotrxate) before being divided equally between fifteen 10cm petri-
dishes. These were then incubated in 5% CO2 at 37°C for 20-30 days, the selective media being
changed every 3-4 days until foci were clearly visible. After 2 weeks from the initial
transfection, foci began to develop on the 10nM plates. Eight days later, one focus developed
on the 50nM plates. No other foci developed after 35 days, on the 50nM plates and no foci
developed on the 100nM or 500nM plates.
To "pick" foci, 1mm squares of Whatman 1MM filter paper were first immersed in 0.05%
trypsin, 0.02% EDTA solution. The selective media was carefully removed from the culture
dishes, which were then washed carefully with 5 ml of PBS. The PBS was then removed and,
using sterile forceps, the squares of pre-soaked filter paper were carefully placed onto individual
focus of cells. The squares were left on the foci for 15 seconds before being transferred into
individual wells of a 24-well tissue culture plate containing 1 ml of the appropriate selective
media.
A total of 31 gamma-1 foci were picked, 30 were from the 10nM MTX plates and one was
from the 50nM plates. These cells were allowed to grow in selective media until almost
confluent and the media from individual wells was tested for antibody production. Those clones
producing human antibody were then selected for expansion and specific production analysis.
The results of the specific production assays are presented in Table 16.
The three cell lines (B9, B13 and B15) which showed the best specific productivity levels
were further analyzed and monitored for accurate doubling times, (see Table 17).
Based on specific productivity levels and doubling times it was decided to begin
production of the 500µg quantity of the BAT-1 ?1 antibody using the B15 cell line.
Example 16
Transient expression of BAT-1 ?4 RHc/Rkd variant in COS cells by single- and co-
transfections
The method of Kettleborough et al. was followed to transfect the mammalian expression
constructs into COS cells. Briefly, the DNA (10µg each of the kappa light chain expression
construct pKN110.BAT-1.Rkd and the heavy chain expression construct pG4Dl 10.BAT-1.RHc,
or 13ug of the supervector construct pG4D110.BAT-1.RHc/RKD) was added to a 0.7 ml aliquot
of 107 cells/ml in PBS and pulsed at 1900 V, 25 µF capacitance using a Bio-Rad Gene Pulser
apparatus. Following a 10 minute recovery at RT, the electroporated cells were transferred to
petri-dishes containing 8 ml of DMEM containing 10% FCS and incubated for 72 hrs in 5%CO2
at 37°C. After 72 hrs incubation, the medium was collected, spun to remove cell debris, and
analyzed by capture ELISA for antibody production.
Both the co-transfections and single transfections were carried out in triplicate. The
results are presented in Table 18. The results indicate that expression levels from this single
expression vector are ~4 fold higher than the expression levels observed for the co-transfections.
Example 17
Stable transfection of CROdhfr- mammalian cells with the single vector pG4KD210.BAT-
1.RHc/Rkd and production of stable cell lines
CHOdhfr- cells were propagated in a non-selective media consisting of a-MEM with
ribonucleosides and deoxyribonucleosides, supplemented with 10% Fetal Clone II and 50ug/ml
Gentamicin. Aliquot, 0.7 ml, of 107 cells/ml in PBS was transfected with 13u.g of
pG4KD110.BAT-1.RHc/RKD at 1900 V, 25 µF capacitance using a Bio-Rad Gene Pulser. The
cells were allowed to recover for 10 minutes at room temperature before being transferred to
10cm petri-dishes in 8 ml of non-selective media and then incubated in 5% CO2 at 37°C for 48
hours. Two days following this incubation, the cells were trypsinized, spun down and
resuspended in 150 ml of prewarmed selective media (a-MEM without ribonucleosides and
deoxyribonucleosides, supplemented with 10% dialyzed FBS and 50ug/ml Gentamicin, and
containing either 10nM, 50nM, 100nM or 500nM Methotrexate) before being divided equally
between fifteen 10cm petri-dishes. These were then incubated in 5% CO2 at 37°C for 20-30
days, the selective media being changed every 3-4 days until foci were clearly visible.
After 2 weeks, foci began to develop on the 10nM plates. No foci developed after 35 days
on the 50nM plates and on the 100nM or 500nM plates. Foci were picked as described earlier
(Example 15) and those selected clones producing human antibody were then selected for
expansion and specific production analysis. The results of the specific production assays are
presented in Table 19.
Example 18
Co-transfection of NSO cells with BATHC heavy chain and BATkd light chain
amplification vectors and selection of antibody producing cell lines
Expression vectors containing the BATRHc heavy chain cassette (FIG. 16) and the
BATRkd light chain cassettes (FIG.11) were mixed and transfected into the NSO host cell line
by electroporation.
Transfected cells were distributed into 10 96-well plates in Dulbecco's Modified Eagles
medium (DMEM) supplemented with 10% Foetal Bovine Serum (FBS) and 1 mg/ml G418
(Gentamicin) medium. After 10 to 14 days when colonies of transfected cells have developed,
samples of conditioned medium from the wells were assayed for humanized BAT-1 antibody.
Cells from the highest producing wells were picked, and expanded in medium including G418.
The transfection was repeated after one week as a back up and to provide more transfected
cell clones for selection. After 10 days visible colonies of transfected cells had developed, and
conditioned medium from the wells was screened for antibody production. ELISA plates were
coated with sheep anti-human k antibody. 25 µl samples of medium from the wells were
transferred to the ELISA plate and diluted to 100µl in PBS Tween (PBST). The secondary
antibody was HRP-conjugated sheep anti-human IgG (y chain specific) and color was developed
with o-Phenylene Diamine (OPD). Positive wells were examined microscopically and the cells
from the highest producing wells were picked into 1.5 ml of DMEM supplemented with 10%
FBS and 1 mg/ml G418 in 24 well plates. A total of 15 high producing colonies were picked
from the two transfections (Table 20). Two independent cell lines gave antibody production
levels around 40µg/ml or greater.
For amplification using the dhfr gene in the heavy chain vector, an initial two high
producing cell lines have been transferred to medium (DMEM with 10% FCS and lmg/ml
G418) with 0.02 uM Methotrexate added.
Example 19
Transfection of NSO host cell line with a single amplification vector containing BAT-
I.RHc/Rkd ?1 gene and selection of antibody producing cell lines
The combined (single) antibody expression vector described in Example 9, was transfected
into the NSO host cell line by electroporation.
Transfected cells were distributed into 10 96-well plates in DMEM with 10% FBS. After
2 days an equal amount of medium with 0.1µM Methotrexate was added. Half the medium was
changed with the same volume of 0.1µM MTX-containing medium every 2 days until the 8th
day post transfection. The transfection was repeated after one week as a back up and to provide
more transfected cell clones for selection. After 14-21 days visible colonies of transfected cells
had developed, and conditioned medium from the wells was screened for antibody production as
described in the above Example. Positive wells were examined microscopically and the cells
from the highest producing wells were picked into 1.5 ml of DMEM supplemented with 10%
FBS and 0.1µM Methotrexate in 24 well plates. A total of 13 high producing colonies were
picked from the two transfections and kept frozen in liquid nitrogen (Table 20). Six
independent cell lines gave antibody production levels above 40µg/ml. Due to the different
selection, the cell lines containing the single vector were slower to develop than those
containing the antibody genes on 2 different vectors.
A representative example of the humanized BAT producing cells after transfection of an
NSO host cell line with a single amplification vector containing BAT-1.RHc/R.Kd ?1 gene and
selection of antibody producing cell lines, i.e., cloned cell line 1B7, was deposited at the ATCC
Cell Bank using the Budapest Treaty Deposit Form on May 9, 2003 under accession number
ATCC#(PTA-5189).
Example 20
Inhibition of mouse BAT-1 by humanized BAT-1.RHc/Rkd ?1 variant
To assure that the humanized BAT-1.RHc/Rkd ?1 variant can recognize the same epitope
as the original murine BAT-1, a competition assay of binding to Daudi cells that express the
BAT-1-binding epitope was conducted.
Daudi cells were incubated with increasing amounts of the humanized BAT-1 or the mouse
BAT-1 as control (0-80 µg/ml). Unbound antibody was discarded and biotinylated murine-BAT-
1 (20 µg/ml) added to the cells and stained with streptavidin-FITC. Figure 24 depicts a decreased
binding of murine BAT-1 in the presence of increasing concentrations of both the humanized
and original mouse mAb, supporting the recognition of the same epitope as expected. Both
antibodies show a similar dose dependency, with an IC50 of approximately 10 µg/ml, suggesting
a similar affinity of antigen binding.
Example 21
In vivo effect of humanized BAT-1 in a murine tumor model
As shown in Example 20, CDR grafting resulting in the formation of the humanized BAT-
1.RHc/Rkd ?1 mAb retained recognition of BAT-1 antigen. To examine whether this binding
can transmit the biological effects characteristic of murine BAT-1, the efficacy of the humanized
BAT-1 was studied in vivo. This is of particular importance in view of the isotype difference
between the mouse and human mAbs.
C57BL mice were inoculated with B16 melanoma cells to induce lung metastases.
Increasing amounts (1,10 and 20 µg) of humanized mAb were injected on day 12 post tumor-
inoculation and compared to an optimal dose of 10µ.g murine-BAT-1. Lung weight measured on
Day 24 post tumor inoculation is depicted in FIG. 25 and corresponds to the establishment of a
tumor. Bom non-treated mice and mice treated with an isotype-inatched irrelevant human IgG1,
had an average lung weight of 0.9 gr. The humanized BAT-1 exhibited a dose dependent
inhibition of metastases growth with the highest inhibition occurring at a low dose of 1µg/mouse.
This resulted in a decrease of 67% in tumor mass and was similar to that achieved by an optimal
dose of murine BAT-1 (62%). Importantly, this maximal effect was achieved by a ten-fold lower
dose of the humanized mAb, suggesting a higher therapeutic efficacy of this antibody in
comparison to the original murine BAT-1 mAb.
Example 22
Inhibition of Human Melanoma (SK-28) in SCID Mice by hBAT-1
Mouse-BAT-1 mAb has been shown to inhibit the formation of human-tumor metastases
in the presence of human peripheral blood lymphocytes (hPBL). To estimate the efficacy of
humanized BAT-1.RHc/Rkd ?1 mAb in inhibition of human cancer, the humanized antibody
was studied in a model combining both tumors and lymphocytes of human origin. Severe
combined immune-deficient mice (SCID) were engrafted with hPBL to restore immune-
competence. Mice were challenged with human melanoma cells (SK-28) and treated with
increasing concentrations of the humanized antibody, administered in a single i.v. dose on day
11 post tumor inoculation. Fig 26 depicts lung weight that correlates with the number of
metastases observed, as measured on day 23. Both concentrations of the humanized antibody
induced tumor inhibition in the presence of hPBL. As observed in the mouse tumor model
described above, the humanized antibody could more efficiently inhibit: tumor growth in vivo,
in comparison to mouse BAT-1. A single dose of 1µg of this humanized antibody inhibited
tumor growth by 68% showing a higher efficacy than lOug of the mouse BAT-1 antibody
(30%).
Example 23
Immunotherapy of human colorectal cancer hepatic metastases by hBAT-1
monoclonal antibody in nude mice
LBVI6 and HM7 are two sub-clones of the human CRC cell line LS174T that were selected
for their high mucin synthesis and metastatic potential. The tumor cells were injected into the
exposed spleen of anesthetized nude mice. After 1 minute, the spleens were removed and the
excisions closed. Low doses of murine and humanized BAT-1 antibody were administered 12
days later and mice were sacrificed 35 days post tumor inoculation. The livers were weighed,
the number of metastatic nodules was counted, and liver tissue was processed for histology and
Immimobistochemistry study.
Treatment with BAT-1, murine and humanized antibodies, was found efficient in
inhibition of liver metastases establishment in the murine model. Mouse BAT-1 antibody
treatment prevented LIM-6 xenografts development. The average weight of xenografts from
BAT-1 treated mice and controls were of 0.14±0.17gr and 0.98+1.12gr, respectively (P=0.004).
HM7 cells injected to the nude mice resulted in large number of bulky metastatic lesions in the
liver that were prevented by the single administration of murine BAT-1 and humanized BAT-1
(Fig. 27). A major (over 40%) decrease was observed in the number of metastatic nodules,
namely from 134.5+34 in the control mice to 8.36+3 and 4.88+2 in mice treated with murine
BAT-1 humanized BAT-1, respectively. Treatment with BAT-1 prevented the accumulation of
lymphocytes in the tumor edge. The role of lymphocyte infiltration around the metastatic
nodule may be related to outcome of the cancer and may suggest a mechanism for BAT-1
therapy.
Example 24
Co-localization of hBAT with CD4 and CD8
Mouse BAT-1 has been shown to bind human lymphocytes, recognizing both CD4+ and
CD8+ subsets. To establish the binding specificity of the humanized BATRHc/BATRkd yl
mAb (hBAT), human Peripheral Blood Lymphocytes (PBL) were isolated from the blood of
normal donors, as described hereinbelow, and analyzed for co-localization of hBAT with known
lymphocyte markers.
Peripheral blood mononuclear cells (PBMC) were isolated by ficoll and incubated in tissue
culture plates to remove adherent cells. Isolated PBL were gated on lymphocytes by size and
granularity and on live cells by propidium iodine (PI) exclusion. Binding was performed at 4°C
for 1 hr, and determined by flow cytometry on gated lymphocytes.
In all samples examined at least 20% of PBL exhibited binding to hBAT. Figure 28
depicts an example of binding to lymphocytes of a selected donor in which 50% of the isolated
PBL were positive for hBAT, including both CD4+ cells (25%) and CD8+ cells (15%). Within
these subpopulations, the majority of CD4+ as well as CD8+ cells bound the hBAT mAb (58%
and 71% respectively).
Example 25
Binding of hBAT to B lymphocytes
The humanized BATRHc/BATRkd yl mAb (hBAT) was raised against the membranes of
Daudi cells, a human B lymphoma cell-line. PBL from normal donors were isolated by ficoll, as
described above, followed by adherence to tissue culture plates. Non-adherent cells were
examined for the co-localization of hBAT with B-cell markers including CD19 and CD20.
Binding was performed at 4°C for 1 hr, and determined by flow cytometry on gated
lymphocytes. Figure 29 depicts the evaluation of binding to the cells of a representative normal
donor.
25-29% of lymphocytes in the sample were positive for the humanized BAT mAb. These
cells included the majority of B cells (70-75%) as demonstrated by both independent markers.
70% of CD20+ were positive for the humanized BAT mAb (Gated on R1 and PI negative; Fig.
29A) and 75% of CD19+ were positive for the humanized BAT mAb (Gated on R1 and PI
negative). The results suggest that the BAT-binding moiety on the cell surface could be common
to peripheral B cells.
Example 26
Binding of hBAT to CD4+ T cells increases upon activation of the cells
Binding of the mouse BAT antibody has been formerly con-elated with lymphocyte
activation. This binding activity was further studied for the human mAb and the binding level of
the human BAT mAB to human CD4+ T cells, subjected to activation, was examined. Cells
were isolated from a normal donor by negative selection and stimulated with beads conjugated
to anti-CD3 and anti-CD2S (5j_il/ml). This treatment was selected in order to exert polyclonal
activation through the T-cell receptor and co-stimulatory molecules.
Cells were examined for binding of the humanized BATRHc/BATRkd yl mAb (hBAT)
and anti-CD4 (4°C, 1 hr) on day 0, 2 and 5 following activation (Fig. 30A, B and D). Analysis
was performed by flow cytometry on cells negative for PI staining. Quadrants were determined
by isotype controls.
The binding of the humanized BATRHc/BATRkd ?1 mAb to CD4+ cells increased
dramatically following activation (Fig. 30). Whereas non-activated cells, at day 0 (Fig. 30A) and
at day 5 (Fig. 30C), exhibited 17-20% positive binding to hBAT, 52% and 77% of CD4+ cells
bound hBAT on day 2 (Fig. 3 OB) and day 5 (Fig. 30D) of activation, respectively. Similar
results were obtained with multiple samples and could also be demonstrated for CD8+ cells.
This demonstrates mat hBAT binding to T cells is increased upon TCR activation.
The dose dependency of this activation was demonstrated by co-localization of hBAT with
CD69. T cell activation is characterized by cell-surface expression of various molecules, some
of which have been shown to be involved in the activation process. hBAT was studied for its co-
expression with different markers including both early and late activation molecules. CD69, an
early activation marker, is up-regulated on T cells upon activation. Four days following
activation, cells were examined for binding of hBAT and anti-CD69 (4°C, 1 hr). Analysis was
performed by flow cytometry on cells negative for PI staining. Quadrants were determined by
isotype controls.
A dose-dependent activation of CD4+ T cells from a normal donor is demonstrated in
figure 31. Upon strong activation (5 µ1/ml of beads conjugated to anti-CD3 and anti-CD28; Fig.
31B) most of the cells, which were capable of binding to hBAT (93%), were activated cells and
were identified by CD69 expression. Increased time of activation also resulted in increase
binding to hBAT beginning at day one of activation. Time dependency of activation could also
be demonstrated and resulted in an increase in hBAT binding beginning at day one of activation.
Interestingly, hBAT binding to both CD4+ and CD8+ cells remained high even after CD69
decrease (day 5) suggesting a correlation of binding with multiple stages of lymphocyte
activation. hBAT binding to CD69+ cells suggests that the expression of hBAT binding protein
is correlated with early activation.
Example 27
Binding of hBAT to activated T cells expressing CD25 and CD40-Ligand
CD25, the high-affinity receptor for IL2, is vital for T-cell expansion and is typically
increased on the surface of activated cells. Chronologically it follows the appearance of CD69
and its expression is extended several days after the down-regulation of CD69.
CD4+ T cells were isolated from a normal donor by negative selection and stimulated for
several days with beads conjugated to anti-CD3 and anti-CD28 (5µ1/rm). Cells were examined
for binding of hBAT and anti-CD25 (4°C, 1 hr) on day 0 (Fig. 32A), day 1 (Fig. 32B), and day 5
(Fig. 32D) of activation with respect to controls (day 0, Fig. 32A and day 5 of no activation, Fig.
32C). Analysis was performed by flow cytometry on cells negative for PI staining. Quadrants
were determined by isotype controls.
Both CD4+ and CD8+ T cells showed a time dependent increase in CD25 expression upon
anti-CD3 and anti-CD28 stimulation, beginning at day 1 of stimulation. hBAT co-localized
with CD25 on these activated cells (Fig. 32).
CD25 expression increased from 55% of the cells on day 1 (Fig. 32B) to 93% on day 5
(Fig. 32D) following activation. At both time points the majority of hBAT binding cells were
CD25+ (85% and 98% respectively).
Correlation with activation markers was further extended to the late activation marker
CD40-Ligand (Fig. 33). hBAT binding positively correlated with the expression of CD40-
Ligand in CD4+ (Fig. 33) and CD8+ T cells in a time dependent manner. The results culminate
to suggest that activation of T cells induces the expression of the hBAT binding protein in a
manner that correlates with different activation stages.
Example 28
hBAT increases survival of activated CD4+ cells
To examine whether activated T cells can be further stimulated by the hBAT, human
CD4+ cells were isolated from normal donors by negative selection and activated with a
suboptimal concentration (0.25 µl/ml) of anti-CD3/CD28 beads (Fig. 34). hBAT (0.5µg/ml) was
added 2 days following activation and its effect was evaluated by determining the number of
viable cells. The results indicate that hBAT induced a significant increase in the number of
viable CD4+ cells isolated from the two separate donors (Fig. 34A and B). Control
nonstimulated cells died within eight days of isolation whereas activated cells expanded in a
manner that is typical of lymphocytes, commencing with cell proliferation followed by a stage
of stable cell number leading to a stage dominated by cell death. The addition of hBAT
enhanced the expansion of CD4+ cell and increased the number of cells by 1.5 folds with
respect to cells in the absence of the mAb.
The fact that the efficacy of BAT antibody in vivo is increased in the presence of tumor
together with the results herein, suggests that the increased efficacy may depend on the presence
of activated BAT target cells. Lymphocytes directed against tumor antigens have been observed
in cancer patients, albeit inefficient in the inhibition of tumor growth, and may serve as target
cells for BAT activity. Thus, in view of the results it may be implied that hBAT activates CD4+
cells by stimulating cell proliferation and/or by inhibiting cell death.
Example 29
Binding of hBAT to Daudi and Jurkat cell lines
Mouse BAT-1 was raised against membranes of the Daudi B-cell line and has been shown
to bind human T cells. To verify the specificity of the humanized antibody, hBAT was examined
for its binding to two human cell lines of myeloid origin: Daudi cells - a human B cell
lymphoma line and Jurkat cells - a human T cell leukemia line. hBAT conjugated to FITC was
incubated with Daudi and Jurkat cells at a concentration of 150ug/ml (4°C for 1 hr). Binding
was determined by flow cytometry.
Both cell lines, Daudi (Fig. 35A) and Jurkat (Fig. 35B) bound the humanized antibody.
Moreover, most of the cells in culture of both lines were capable of binding the antibody. An
isotype matched human-IgGl served as a negative control (Fig. 35; isotype control) and
established the reading threshold. Both cell lines demonstrated a similar intensity of antibody
staining suggesting that they express a similar number of hBAT binding molecules.
Example 30
Binding of hBAT to PBL of cancer patients
Following the observation that hBAT is capable of binding human T cells from normal
donors, we compared its ability to bind lymphocytes collected from cancer patients. PBL were
isolated from the blood of a prostate cancer patient by ficoll followed by adherence to tissue
culture plates. Non-adherent cells were examined for binding of hBAT and lymphocyte markers.
Binding was performed at 4°C for 1 hr, and determined by flow cytometry on gated
lymphocytes. Isotype controls were used to determine the quadrants. These patients have
formerly undergone therapy that often affects the presence and phenotype of lymphocytes.
hBAT binding to these cells is a pre-requisite for its activity and as depicted in figure 36,
resembles the binding to lymphocytes of normal donors. Although total lymphocyte numbers
were low, hBAT could still bind a large proportion of the lymphocyte subpopulations which we
examined including 39% of CD4+ cells, 60% of CD8+ cells and 68% of B cells.
Example 31
Cross reactivity of hBAT with human, primate and murine tissues
The purpose of this study was to examine the cross reactivity of hBAT-1 monoclonal
antibody with a range of normal human tissue. This study involved immunohistochemical
testing of the monoclonal antibody against-a range of human tissues. A comparison of in vitro
cross-reactivity in tissues from cynomologus monkey and CD-1 mice was also undertaken.
(i) Tissue source
The tissues used in this study were each obtained from three unrelated donors to minimize
the chances of donor specific factors affecting antibody binding. The human tissue was provided
by an ethical source. The primate and murine tissues used in this study were obtained from two
animals of each species, by an ethical source. The murine and primate are potential test systems
that may be evaluated in pre-clinical toxicology Studies. The tissues selected were those
specified in the FDA Points to Consider in the Manufacture and Testing of Monoclonal
Antibody Products for Human Use (Office of Biologies Research and Review. Center for
Biologies Evaluation and Research FDA. 1997) and the Rules Governing Medicinal Products in
the European Community Vol. 3a (Production and Quality Control of Monoclonal Antibodies
Dec. 1994, 3AB4a). All tissues used in this investigation were snap frozen in liquid nitrogen and
stored at or below -70°C until required. Cryostat sections were prepared at a nominal thickness
of 5 µm to 8 µm. The positive control was Jurkat E6 cells. Samples of fresh blood were
collected from 3 donors and smears prepared on the day of use.
(ii) FITC Conjugation
The humanized monoclonal hBAT-1 antibody was conjugated to FITC by the Custom
Antibody Services Division of Serotec Ltd (ISO 9001, Certification) before the study was
started. The final concentration of the conjugated antibody was 1.99 mg/ml.
Initial validation of the methodology was performed on control tissue (Jurkat E6 cell line)
to determine the titer concentration for antibody-tissue binding with frozen sections and other
conditions relevant to the proper performance of the antibody-tissue binding. Slides were
microscopically examined and scored subjectively against the antibody specificity (Table 21).
Based on these data, the concentrations of hBAT-1 that were used throughout the study were
1:100, 1:250 and 1:500.
positive staining and 0 refers to no staining/signal. +++ refers to strong visual signal, ++ refers
to good visual signal and + refers to weak visual signal.
(iii) Controls.
Negative control reactions, in which the antibody was substituted with a buffer, were
carried out for each tissue. Each detection reaction included positive control cells, Jurkat E6,
reacted at the three predetermined dilutions of the antibody. This allowed the consistency of the
reaction to be monitored. Sections of thyroid, incubated with anti actin antibody, were included
in each assay run as controls for the detection system.
(iv) Cross-reactivity Assessment
Sections of each tissue were stained with Haematoxylin and Eosin (H&E) to confirm then-
identity and suitability for the study. Sections were also incubated with anti smooth muscle actin
(SMA; Table 22) or rabbit anti human transferrin control sera, which showed the tissues were
suitable for immunohistochemistry. Three sections of each of the tissues were prepared and
incubated with the antibody, which had been conjugated to FITC, at concentrations of 1:100,
1:250 and 1:500 as determined during the validation phase. After washing in buffer and
blocking with normal serum, the sections were incubated with the appropriate secondary and
tertiary antibodies for alkaline-phosphatase detection, and counter-stained with haematoxylin
before microscopical examination to determine sites of binding.
The FITC -conjugated staining method with Alkaline Phosphatase detection contained the
following steps:
1. Air dry cryostat sections.
2. Fix by immersion in acetone, 10 minutes at room temperature
3. Air dry.
4. Buffer wash.
5. Normal serum, 1:5, at least 20 minutes.
6. Buffer wash
7. 1022292 test FITC conjugated antibody at 1: 100, 1 :250 and 1 :500, :. overnight at 2-
8°C.
8. Buffer wash.
9. Monoclonal anti FITC antibody, 1:50,30 minutes.
10. Buffer wash.
11. Alkaline phosphatase conjugated antibody, 1 :200, 2 hours. 12. Buffer wash.
13. Vector red and levamisole, 20 minutes.
14. Buffer wash.
15. Counterstain and mount.
Endogenous alkaline phosphatase was minimized by using Levamisole incorporated into
the chromogen. In tissues where endogenous alkaline phosphatase activity could not be
suppressed (human colon, ileurn, placenta and endothelium, murine colon and pancreas, primate
stomach, ileum and prostate), horseradish peroxidase conjugated antibody at 1:200 for 2 hours
was used, followed by Diaminobenzidene (DAB) reagent for 20 minutes.
(v) Results
Samples of individual tissues stained with H&E were examined for quality of tissue,
presence of normal histological features and adequacy of preservation. All samples that were
tested were considered to be suitable for the purposes of this study. Positive staining was
achieved in the Jurkat E6 cell line for hBAT-1 and in the thyroid sections treated with smooth
muscle actin. As the controls gave the expected results, the test was considered valid.
Individual cross reactivity results for hBAT-1 and human tissues are shown in Tables 22.
Positive staining was detected in blood vessels human endothelium at a dilution of 1:100 and
was probably a result of hBAT-1 binding to lymphocytes. Positive staining indicates probable
tissue binding of the humanized monoclonal hBAT-1 antibody. No staining, i.e. cross reactivity
with hBAT-1, was observed in spleen sections, blood smears or other human tissues (except
human endothelium - blood vessels). None of the murine and primate tissues showed evidence
of cross reactivity with hBAT-1.
The foregoing description of the specific embodiments will so fully reveal the general
nature of the invention that others can, by applying current knowledge, readily modify and/or
adapt for various applications such specific embodiments without undue experimentation and
without departing from the generic concept, and, therefore, such adaptations and modifications
should and are intended to be comprehended within the meaning and range of equivalents of the
disclosed embodiments. It is to be understood that the phraseology or terminology employed
herein is for the purpose of description and not of limitation. The means, materials, and steps for
carrying out various disclosed functions may take a variety of alternative forms without
departing from the invention. Thus the expressions "means to..." and "means for...", or any
method step language, as may be found in the specification above and/or in the claims below,
followed by a functional statement, are intended to define and cover whatever structural,
physical, chemical or electrical element or structure, or whatever method step, which may now
or in the future exist which carries out the recited function, whether or not precisely equivalent to
the embodiment or embodiments disclosed in the specification above, i.e., other means or steps
for carrying out the same functions can be used; and it is intended that such expressions be given
their broadest interpretation.
CLAIMS:
1. An humanized monoclonal antibody having at least one complementarity
determining region (CDR) of murine monoclonal antibody produced by the
hybridoma cell line deposited at the CNCM under Accession No. 1-1397 (mBAT-1)
and a framework region (FR) derived from an acceptor human immunoglobulin
wherein the humanized antibody retains the anti-tumor activity of mBAT-1
monoclonal antibody and is less immunogenic in a human subject than said murine
antibody.
2. The humanized monoclonal antibody as claimed in claim 1, wherein the
humanized antibody induces a greater anti-tumor effect than that induced by the
parent murine mBAT-1 antibody.
3. The humanized antibody as claimed in claim 1, comprising the
complementarity-determining regions (CDRs) of mBAT-1, wherein said humanized
antibody comprises:
a. light chain variable regions of the formula:
FRli-CDRl1- FRl2-CDRL2- FRl3-CDRL3- FRL4
wherein each FR is independently a framework region of a human
antibody, and each CDR is a complementarity determining region,
derived from mBAT-1;
b. the heavy chain variable regions of the formula:
FRh1-CDRh1- FRh2-CDRh2- FRh3-CDRH3- FRH4
wherein each FR is separately a framework region of a human antibody, and
each CDR is a complementarity determining region, form mBAT-1.
4 A monoclonal antibody having a genetically modified Fab region comprising
the complementarity-determining regions (CDRs) of mBAT-1, wherein the genetically
modified antibody retains the biological activity of said mBAT-1 and wherein said
genetically modified monoclonal antibody comprises an amino acid sequence selected
from:
(i) a heavy chain variable region comprising the amino acid sequences of:
CDRh1 (SEQ ID NO:12); CDRH2 (SEQ ID NO: 13); CDRH3 (SEQ ID
NO:14); and a light chain variable region comprising the amino acid
sequences of: CDRL1 (SEQ ID NO:9); CDRl2 (SEQ ID NO: 10); CDRL3
(SEQ ID NO: 11);
(ii) heavy chain and light chain variable regions comprising the amino acid
sequences having greater than about 80 percent similarity to all or part
of the sequences of: CDRH1 (SEQ ID NO: 12); CDRH2 (SEQ ID
NO: 13); CDRH3 (SEQ ID NO: 14); CDRl1 (SEQ ID NO:9); CDRl2
(SEQ ID NO: 10); CDRL3 (SEQ ID NO: 11);
(iii) an antibody of (i) or (ii) in which one or more amino acid residues have
been added, deleted, replaced or chemically modified without
substantially affecting the biological activity or binding specificity of
the antibody.
5. The monoclonal antibody as claimed in claim 4, wherein the framework
regions (FRs) are derived from a human antibody.
6. The humanized monoclonal antibody as claimed in claim 3, comprising
complementarity-determining regions (CDRs) of mBAT-1, wherein said humanized
antibody comprises:
a. light chain variable regions of the formula:
FRl1-CDRl1- FRL2-CDRl2- FRL3-CDRl3- FRL4
wherein each FR is independently a framework region of a human
antibody, and each CDR is a complementarity determining region, wherein
the amino acid sequence of DRL1 is SARSSVSYMH (SEQ. ID NO. 9);
CDRL2 is RTSNLAS (SEQ. ID NO. 10); CDRl3 is QQRSSFPLT (SEQ. ID
NO. 11);
b. the heavy chain variable regions of the formula:
FRh1-CDRh1- FRH2-CDRH2- FRH3-CDRH3- FRh4
wherein each FR is separately a framework region of a human
antibody, and each CDR is a complementarity determining region,
wherein the amino acid sequence of: CDRh1 is NYGMN (SEQ. ID NO.
12); CDRH2 is WINTDSGESTYAEEFKG (SEQ. ID NO. 13); CDRH3 is
VGYDALDY (SEQ. ID NO. 14); and
c. a light chain variable regions of a. or a heavy chain variable regions of
b. wherein one or more amino acid residues have been added, deleted,
replaced or chemically modified without substantially affecting the
biological activity or binding specificity of the antibody.
7. The humanized antibody as claimed in claim 6, wherein said humanized
antibody induces a greater antitumor effect than murine BAT-1 monoclonal antibody.
8. The humanized antibody as claimed in claim 6, wherein said humanized antibody
induces a greater anti-metastatic effect than murine BAT-1 monoclonal antibody.
9. The humanized antibody as claimed in claim 6, wherein the antibody is a full
length antibody.
10. The humanized antibody as claimed in claim 9, wherein the antibody is of
isotype IgG.
11. The humanized antibody as claimed in claim 10, wherein said isotype subclass is
selected from IgG1 or IgG4.
12. The humanized antibody as claimed in claim 6, wherein the FR of the heavy
chain variable region are derived from the FRs of the heavy chain variable region of
the human hsighv1295 antibody.
13. The humanized antibody as claimed in claim 6. wherein the FRs of the kappa
light chain variable region are based on the FRs of the kappa light chain variable
region of the human TEL9 antibody.
14. The humanized antibody as claimed in claim 6, having a human kappa constant
region.
15. An antibody fragment derived from humanized antibody as claimed in claim 6,
wherein the antibody fragment is selected from the group consisting of: Fv, F(ab'), F
(ab')2, a single chain antibody.
16. The humanized antibody as claimed in claim 6, wherein the antibody is further
labeled with a detectable label, immobilized on a solid phase, or conjugated to a
heterologous compound.
17. The humanized antibody as claimed in claim 6, wherein said humanized
monoclonal antibody light chain variable regions are selected from the group
consisting of: BATRk a (SEQ. ID NO. 15), BATRk b (SEQ. ID NO. 16),
BATRk c (SEQ. ID NO. 17), BATRk d (SEQ. ID NO. 18), and the heavy chain
variable regions are selected from the group consisting of: BATRBU (SEQ. ID NO.
20), BATRHb (SEQ. ID NO. 21), BATRHc (SEQ. ID NO. 22), BATRHd (SEQ. ID
NO. 23) or BATRHe (SEQ. ID NO. 24).
18. The humanized antibody as claimed in claim 6, wherein said humanized
monoclonal antibody variable regions are selected from the group consisting of:
BATRHa/BATRk a (SEQ. ID NO. 20/SEQ. ID NO. 15), BATRHb/BATRk a
(SEQ. ID NO. 21/SEQ. ID NO. 15), BATRHb/BATRk b (SEQ. ID NO. 21/SEQ. ID
NO. 16), BATRHc/BATRk b (SEQ. ID NO. 22/SEQ. ID NO. 16),
BATRHb/BATRk d (SEQ. ID NO. 21/SEQ. ID NO. 18), or BATRHc/BATRk d
(SEQ. ID NO. 22/SEQ. ID NO. 18).
19. The antibody as claimed in claim 6, generated by recombinant DNA
technology, utilizing CDR grafting.
20. The humanized antibody as claimed in claim 1, wherein said humanized
antibody is produced by cells deposited under ATCC # (PTA-5189).
21. An isolated polynucleotide construct encoding any of the monoclonal antibodies
as claimed in any one of claims 1 - 20, or fragments thereof.
22. The isolated polynucleotide construct as claimed in claim 21, encoding a kappa
light chain variable region selected from the group consisting of: SEQ ID NO. 15,
SEQ ID NO. 16, SEQ ID NO. 17, SEQ ID NO. 18.
23. The isolated polynucleotide construct as claimed in claim 22, selected from the
group consisting of: SEQ ID NO. 87, SEQ ID NO. 88, SEQ ID NO. 89.
24. The isolated polynucleotide construct as claimed in claim 21, encoding a heavy
chain variable region selected from the group consisting of: SEQ ID NO. 20, SEQ ID
NO. 21, SEQ ID NO. 22, SEQ ID NO. 23, SEQ ID NO. 24.
25. The isolated polynucleotide construct as claimed in claim 24, selected from the
group consisting of: SEQ ID NO. 90, SEQ ID NO. 91, SEQ ID NO. 92.
26. A vector comprising any of the polynucleotides as claimed in any of claims 21
to 25.
27. The vector as claimed in claim 26, further comprising at least one
polynucleotide sequence encoding a component selected from the group consisting of:
a promoter operatively linked to the polynucleotide encoding the antibody, one or
more resistance gene, a Kozak sequence, an origin of replication, one or more
selection marker genes, an enhancer element, transcription terminator, a signal
peptide, genomic human kappa constant region, genornic human IgG constant region.
28. The vector as claimed in claim 27, wherein the vector is a plasmid or a virus.
29. The vector as claimed in claim 28, selected from the group comprising: pKN110,
PG1D200, PG1KD210, pUC or pBR322.
30. The vector as claimed in claim 26, comprising the polynucleotide sequence of
SEQ ID NO. 93.
31. A genetically modified cell comprising the vector as claimed in any one of claims
24-28.
32. The genetically modified cell as claimed in claim 31, capable of expressing an
antibody or fragments thereof.
33. The genetically modified cell as claimed in claim 31, wherein the cell is selected
from eukaryotic and prokaryotic.
34. The genetically modified cell as claimed in claim 31, selected from the group
consisting of: CHO, CHOdhfr, NSO, COS or COS7 cells.
35. A pharmaceutical composition comprising as an active ingredient the antibody
or antibody fragments as claimed in any one of claims 1-20.
36. The pharmaceutical composition as claimed in claim 35, further comprising a
physiologically acceptable carrier, diluent, or stabilizer.
37. A pharmaceutical composition as claimed in claim 35, wherein said composition
is useful for treatment of cancer.
38. The pharmaceutical composition as claimed in claim 37, further comprising an
additional therapeutic agents selected from, cytokines, IL-1 (interleuken-1), IL-2, IL-6,
IFN-a (interferon-a ), cell vaccines, antibodies, T-cell stimulatory antibody, and
anti-tumor therapeutic antibody.
39. The pharmaceutical composition as claimed in claim 37, wherein the cancer is
selected from the group consisting of melanoma, lung tumors, colorectal cancer or
hepatic metastasis.
40. A method for producing the antibody as claimed in any one of claims 1- 20,
comprising:
(i) transfecting a genetically modified cell with a vector comprising a
polynucleotide sequence encoding said antibody, or co-transfecting the
host cell with two vectors each comprising a polynucleotide sequence
encoding the heavy or light chain regions of said antibody;
(ii) culturing the host cell of (i) so that said antibody is expressed; and
(iii) recovering the antibody from the host cells culture of (ii).
The present invention provides a humanized monoclonal antibody having
immuno-stimulatory effects, an isolated polynucleotide sequence encoding same,
methods of producing said humanized antibody and use of said humanized antibody
for the preparation of an anti-cancer medicament. The humanized antibody comprises
CDRs derived from the murine antibody produced by the hybridoma cell line
deposited at the CNCM under Accession No. I-1397 and FRs comprising mainly
residues from a human origin. A complicated and innovative analysis led to the
replacement of certain human residues in the framework of the variant portion with
the original murine antibody. The resulting humanized antibody is composed of an
unexpected amino acid sequence and is capable of eliciting an anti-tumor activity
similar or greater than the anti-tumor activity induced by the corresponding murine
antibody.

Documents:

1764-KOLNP-2004-CORRESPONDENCE.pdf

1764-KOLNP-2004-FORM-27-1.1.pdf

1764-KOLNP-2004-FORM-27.pdf

1764-KOLNP-2004-FROM 27.pdf

1764-kolnp-2004-granted-abstract.pdf

1764-kolnp-2004-granted-assignment.pdf

1764-kolnp-2004-granted-claims.pdf

1764-kolnp-2004-granted-correspondence.pdf

1764-kolnp-2004-granted-description (complete).pdf

1764-kolnp-2004-granted-drawings.pdf

1764-kolnp-2004-granted-examination report.pdf

1764-kolnp-2004-granted-form 1.pdf

1764-kolnp-2004-granted-form 13.pdf

1764-kolnp-2004-granted-form 18.pdf

1764-kolnp-2004-granted-form 3.pdf

1764-kolnp-2004-granted-form 5.pdf

1764-kolnp-2004-granted-gpa.pdf

1764-kolnp-2004-granted-reply to examination report.pdf

1764-kolnp-2004-granted-sequence listing.pdf

1764-kolnp-2004-granted-specification.pdf


Patent Number 224749
Indian Patent Application Number 1764/KOLNP/2004
PG Journal Number 43/2008
Publication Date 24-Oct-2008
Grant Date 22-Oct-2008
Date of Filing 22-Nov-2004
Name of Patentee CURE TECH LTD.
Applicant Address HAYARKON STREET 42, 81227 YAVNE
Inventors:
# Inventor's Name Inventor's Address
1 HARDY BRITTA 6 ELIAHU HAKIM STREET, 68120 TEL-AVIV
2 JONES STEVEN TARRAN 1 CHRISTCHURCH CRESCENT, RADLETT, HERTFORDSHIRE WD7 8AG
3 KLAPPER LEAH BEN-ZION STREET 10, 53230 GIVATAIM
PCT International Classification Number C07H 21/04
PCT International Application Number PCT/IL2003/000425
PCT International Filing date 2003-05-22
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 149820 2002-05-23 Israel