U.S. patent application number 10/470940 was filed with the patent office on 2004-04-22 for hybridoma cell line g250 and its use for producing monoclonal antibodies.
Invention is credited to Oosterwijk, Egbert, Ullrich, Stefan, Warnaar, Sven.
Application Number | 20040077081 10/470940 |
Document ID | / |
Family ID | 32096815 |
Filed Date | 2004-04-22 |
United States Patent
Application |
20040077081 |
Kind Code |
A1 |
Oosterwijk, Egbert ; et
al. |
April 22, 2004 |
Hybridoma cell line g250 and its use for producing monoclonal
antibodies
Abstract
The invention relates to a hybridoma cell line which is capable
of producing the monoclonal antibody G250. Furthermore, the
invention describes the method of employing such cell line for the
production and manufacture of monoclonal antibody G250 as well as
derivatives thereof such as chimeric and humanized G250
antibodies.
Inventors: |
Oosterwijk, Egbert; (Lm
Beuningen, NL) ; Warnaar, Sven; (Leiden, NL) ;
Ullrich, Stefan; (Munchen, DE) |
Correspondence
Address: |
ROTHWELL, FIGG, ERNST & MANBECK, P.C.
1425 K STREET, N.W.
SUITE 800
WASHINGTON
DC
20005
US
|
Family ID: |
32096815 |
Appl. No.: |
10/470940 |
Filed: |
August 5, 2003 |
PCT Filed: |
February 7, 2002 |
PCT NO: |
PCT/EP02/01282 |
Current U.S.
Class: |
435/326 ;
424/141.1; 435/252.33 |
Current CPC
Class: |
C07K 2317/56 20130101;
A61K 2039/505 20130101; C07K 16/3038 20130101; C07K 2317/24
20130101; A61P 35/00 20180101; A61K 47/6861 20170801; C07K 2317/565
20130101 |
Class at
Publication: |
435/326 ;
435/252.33; 424/141.1 |
International
Class: |
A61K 039/395; C12N
005/06; C12N 001/21 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 7, 2001 |
US |
60266853 |
Oct 5, 2001 |
US |
60327008 |
Claims
1. Hybridoma cell DSM ACC 2526 which produces the monoclonal
antibody G250.
2. Cell derived from hybridoma cell DSM ACC 2526 which produces a
G250 antibody.
3. The cell according to claim 2 which has been obtained by
transfer of genetic material encoding antibody G250 or at least the
antigenbinding site thereof into a receptor cell.
4. The cell according to claim 2 which produces a chimeric
antibody, a humanized antibody, a fully humanized antibody, a
bispecific antibody, a single chain antibody, or F(ab').sub.2,
Fab', or Fab antibody fragments.
5. The receptor cell according to claim 3 or 4 which is a
prokaryotic cell.
6. The cell according to claim 5 which is an E. coli cell.
7. The cell of claim 3 or 4 which is a eukaryotic cell.
8. The cell according to claim 7 which is a yeast cell, a myeloma
cell or a CHO-cell.
9. A method of producing a G250 antibody comprising: cultivating a
cell according to any one of claims 1-7 under suitable conditions,
wherein the antibody is produced and obtaining the antibody from
the cell and/or from the culture medium.
10. The method according to claim 8 used for producing a
pharmaceutical formulation which comprises the G250 antibody as an
active agent.
11. The method according to claim 10, wherein the pharmaceutical
formulation comprises the chimeric G250 antibody.
12. The method according to claim 10, wherein the pharmaceutical
formulation comprises the chimeric G250 antibody in radiolabeled
form.
13. The method according to claim 10, wherein the pharmaceutical
formulation comprises a chimeric G250 antibody coupled to a
cytokine such as IL-2, TNF and/or GM-CSF.
14. Use of a cell according to any one of claims 1-7 for the
manufacture of a G250 antibody.
15. Use of a G250 antibody for the manufacture of an agent for
eliciting a delayed immune response in cancer therapy.
16. The use of claim 15 in the treatment of renal cell
carcinoma.
17. The use of claim 15 or 16 for the treatment of metastases after
tumor surgery.
Description
[0001] The invention relates to the hybridoma cell G250 or any
progeny cell thereof capable of producing G250 antibody.
[0002] The fusion of mouse myeloma cells with the spleen cells from
immunized mice, first described by Kohler and Milstein, Nature,
256, 495-997 (1975), makes it possible to obtain continuous cell
lines which produce homogeneous antibodies, referred to as
monoclonal antibodies (mAb).
[0003] Many examples exist where hybrid cells or hybridomas are
described. These hybridomas are used to produce antibodies useful
for various scientific investigations (Current Topics in
Microbiology and Immunology, volume 81--"Lymphocyte Hybridomas", F.
Melchers et al., Springer-Verlag (1978) and references therein; C.
J. Barnstable et al., Cell, (1978), 14, 9-20; P. Parham, W. F.
Bodmer, Nature (1978), 276, 397-399; Handbook of Experimental
Immunology, 3rd edition, vol. 2, D. M. Wier, editor, Blackwell,
1978, Chapter 25, Chem. Eng. News, 15-17 (1979); Kennett, R. H.,
McKearn, J. T., and Bechtol, K. B. (1980) Monoclonal Antibodies.
Hybridomas: A New Dimension in Biological Analysis (Plenum, N.Y.)).
These reports describe the principal techniques for the production
of monoclonal antibodies by hybridomas.
[0004] The monoclonal antibody G250, subclass IgG1, recognizes an
antigen preferentially expressed on membranes of renal cell
carcinoma cells (RCC) and not expressed in normal proximal tubular
epithelium. The antibody G250 was obtained by immunizing a mouse
with cell homogenates from primary RCC lesions obtained from
different patients (Oosterwijk et al., Int. J. Cancer 38 (1986),
489-494).
[0005] The monoclonal antibody G250 as well as chimeric derivatives
thereof have been used in clinical studies (Steffens et al., J.
Clin. Oncol. 15 (1997), 1529-1537). The nucleic acid sequence
coding for the antigen-binding site of G250 is subject matter of
co-pending U.S. application No. 60/266 853, which is herein
incorporated by reference.
[0006] The production of a hybridoma cell line expressing G250
antibody was generally described in the international patent
application WO88/08854 and Oosterwijk et al. (supra). As stated
above, a cell homogenate from primary RCC lesions obtained from
different patients and thus an unspecific material was used as an
immunogen. Furthermore, the hybridoma cell line had not been
deposited with a recognized depository institution according to the
Budapest Treaty. Thus, an exact reproduction of the G250 hybridoma
cell line from the publically available prior art documents does
not seem to be possible.
[0007] Meanwhile it has been found that the G250 antibody binds to
the so-called MN antigen which is described e.g. in WO93/18152. The
G250 binding site on the MN antigen is, however, not known at
present. Moreover, recent results show that the G250 binding site
is a conformational epitope which further increases the burden to
reproduce the G250 hybridoma cell line, since no specified epitope
sequence on the MN antigen which binds to G250 can be provided.
[0008] Thus, the present invention relates to a hybridoma cell
capable of producing a G250 monoclonal antibody. This hybridoma
cell was deposited under the Budapest Treaty for the Deposit of
Microorganisms on Sep. 11, 2001 at Deutsche Sammlung von
Mikroorganismen und Zellkulturen GmbH (DSMZ), Mascheroder Weg 1b,
38124 Braunschweig, Germany under the Accession Number DSM ACC
2526. The deposit is the first publically available disclosure of a
G250 antibody producing hybridoma cell line.
[0009] A further aspect of the invention is a progeny cell derived
from said hybridoma DSM ACC 2526 which produces a G250
antibody.
[0010] In a preferred embodiment, the present invention relates to
a progeny cell of the deposited hybridoma cell producing a G250
antibody wherein the progeny cell is obtained by recombinant DNA
methods, e.g. by transferring genetic material encoding the G250
antibody or at least the antigen-binding site thereof into a
receptor cell. The genetic material may be directly or indirectly
obtained from the deposited hybridoma cell G250. "Directly
obtained" means that the G250 genetic material is derived from the
deposited hybridoma cell. "Indirectly obtained" means that the G250
genetic material is derived from an already existing G250 progeny
cell or from other sources including chemical synthesis.
[0011] Preferably the G250 genetic material comprises nucleotide
sequences encoding at least the G250 antigen-binding site,
particularly nucleotide sequences encoding the complementary
determining regions CDR3, CDR2 and/or CDR1 of the heavy chain
antigen-binding site as shown in FIG. 1 (designated H1-H3) and/or
the complementary determining regions CDR3, CDR2 and/or CDR1 of the
light chain antigen-binding site (designated L1-L3) as shown in
FIG. 1.
[0012] According to the invention the term "G250 antibody" covers
any antibody including multispecific antibodies (e.g. bispecific
antibodies) and antibody fragments as long as they exhibit the
desired activity, i.e. at least one G250 antigen-binding site. The
antibody may be an IgM, IgG (e.g. IgG.sub.1, IgG.sub.2, IgG.sub.3
or IgG.sub.4), IgD, IgA or IgE, particularly IgG antibody, a
recombinant antibody or an antibody fragment obtained by
proteolytic methods or by recombinant DNA methods.
[0013] The term "monoclonal antibody" as used herein refers to an
antibody obtained from a population of substantially homogeneous
antibodies, i.e., the individual antibodies comprising the
population are identical, except for possibly naturally occurring
mutations that may be present in minor amounts.
[0014] The term "antibody" as used herein refers to any polypeptide
containing at least one G250 antigen-binding site, i.e. at least
the CDR3 region of the G250 heavy chain and/or the CDR3 region of
the G250 light chain or a variant G250 CDR3 region having an
identity of at least 80%, preferably at least 90% to the original
G250 CDR3 region on the amino acid level, provided that the variant
CDR3 region has equivalent antigen-binding characteristics,
particularly affinity and specificity compared to the original CDR3
region.
[0015] Preferably, the term "antibody" herein includes chimeric
antibodies, humanized and fully humanized antibodies, single chain
antibodies, e.g. sFv antibody fragments, diabody fragments,
proteolytic or recombinant antibody fragments such as Fv-, Fab-,
Fab'- or F(ab').sub.2-fragments or other antigen-binding
subsequences of antibodies. The antibody may also be a fusion or a
conjugate with other entities.
[0016] The antibodies herein specifically include chimeric
antibodies in which a portion of the heavy and/or light chain
including the antigen-binding site is identical with or homologous
to corresponding sequences derived from the original hybridoma cell
line G250, while the remainder of the chains is identical with or
homologous to corresponding sequences derived from other species or
belonging to another antibody class or subclass as well as
fragments of such antibodies as long as they exhibit the desired
biological activity. More preferably, the chimeric antibody
comprises variable regions, e.g. the complement-determining regions
(CDRs) and and the framework regions from the heavy chain and the
light chain of the original G250 monoclonal antibody and constant
human sequences, particularly constant human kappa light chain and
gamma heavy chain sequences. The manufacture of chimeric antibodies
is described e.g. by Morrison et al. (Proc. Natl. Acad. Sci. USA 81
(1984), 6851-6855), which is herein incorporated by reference.
[0017] Further, antibody herein specifically includes humanized
antibodies or fully human antibodies. Humanized antibodies are
immunoglobulins, immunoglobulin chains or fragments thereof which
contain minimal sequence derived from non-human immunoglobulin.
More particularly, humanized antibodies are human immunoglobulins
in which residues from a CDR of a given human antibody are replaced
by residues from the G250 CDR, particularly the CDR1, 2 and/or 3
region of the heavy and/or light chain. Furthermore, humanized
antibodies may comprise residues which are found neither in the
recipient human antibody, nor in the imported G250 CDR sequences.
These modifications are made to further refine and optimize
antibody performance. In general, the humanized or fully human
antibody will comprise substantially all of at least 1, and
typically 2, variable domains, in which all or substantially all of
the CDR regions correspond to those of the original G250
immunoglobulin and all or substantially all of the framework
regions and constant regions are those of a human immunoglobulin
sequence. The manufacture of humanized antibodies is described,
e.g. in Jones et al. (Nature 321 (1986), 522-525), Riechmann et al.
(Nature 332 (1988), 323-329 and Presta (Curr. Op. Struct. Biol. 2
(1992), 332-339), which are herein incorporated by reference.
[0018] Further, antibodies specifically include single-chain
antibodies such as single-chain Fv antibody fragments comprising
the VH and VL domains of an antibody, wherein these domains are
present in a single polypeptide chain. Generally, the Fv
polypeptide further comprises a polypeptide linker between the VH
and VL domains which enables the sFv to form the desired structure
for antigen binding. The manufacture of sFv antibodies is described
e.g. by Pluckthun in: The Pharmacology of Monoclonal Antibodies,
Vol. 113, Rosenburg and Moore, Eds., Springer Verlag, NY, pp.
269-315 (1994), Barbas III (Methods: Companion Methods Enzymol. 2
(1991), 119) and Hoogenboom etal. (Immunol. Rev. 130 (1992),
41-68), which are herein incorporated by reference.
[0019] Further, antibodies specifically include diabodies, i.e
small antibody fragments with two antigen-binding sites, which
fragments comprise a heavy chain variable domain connected to a
light chain variable domain in the same polypeptide chain. By using
a linker that is too short to allow pairing between the two domains
on the same chain, the domains are forced to pair with the
complementary domains of another chain and create two antigen
binding sites. The manufacture of diabodies is described e.g. by
Hollinger et al., (Proc. Natl. Acad. Sci. USA 90 (1993),
6444-6448), which is herein incorporated by reference.
[0020] Further, antibodies specifically include multispecific
antibodies e.g. heterobispecific antibodies comprising at least one
G250 antigen-binding site and the antigen-binding site from a
different antibody, e.g. an anti-CD3-antibody.
[0021] The antibody produced by the G250 hybridoma cell or a
progeny cell thereof may be fused or coupled to a marker or
effector component. For example, the G250 antibody may be
recombinantly modified so that it is linked to cytokines such as
interleukin-2 (IL-2), tumor necrosis factor (TNF) and/or
granulocyte macrophage colony stimulating factor (GM-CSF).
[0022] Furthermore, the G250 antibody may be conjugated, e.g. by
covalent coupling or fused to a suitable marker group, e.g. a
fluorescent group, a radioactive marker group etc. or a cytotoxic
agent including radioactive isotopes such as I, Y, Pr, Tm, In, such
as .sup.123I, .sup.125I, .sup.135I, .sup.99mTm or .sup.111In,
chemotherapeutic agents and toxins such as enzymatically active
toxins of bacterial, fungal, plant or animal origin, or fragments
thereof.
[0023] The receptor cell into which G250 specific genetic material
from the original G250 hybridoma cell or any progeny thereof or of
synthetic origin is transferred may be any suitable host cell
capable of expressing antibodies. For example, the host cell maybe
a prokaryotic cell, preferably an E. coli cell or a eukaryotic
cell. Preferred eukaryotic cells are e.g. insect, yeast and
mammalian cells. Most preferred host cells are mammalian cells,
e.g. human or mouse myeloma cells or CHO-cells.
[0024] Further, the present invention comprises a method of
producing G250 antibody or derivatives thereof comprising:
[0025] cultivating a G250 hybridoma cell or a progeny cell thereof
under suitable conditions, wherein a G250 antibody is produced and
obtaining the antibody and/or derivative thereof from the cell
and/or from the cell culture medium.
[0026] The antibody obtained according to this method is
particularly useful for producing pharmaceutical formulations which
comprise the antibody as an active agent, besides pharmaceutically
acceptable carriers, diluents and/or adjuvants.
[0027] In an especially preferred embodiment, the active agent is a
chimeric G250 antibody which may be present as such or as a
conjugate with a radioactive group, e.g. with .sup.123I, .sup.125I,
.sup.131I, .sup.99mTm or .sup.111In.
[0028] Further, the present invention relates to the use of the
deposited hybridoma cell and progeny cells thereof for
manufacturing G250 antibodies as described above, e.g. monoclonal
antibodies, chimeric antibodies, humanized antibodies, fully
humanized antibodies, bispecific antibodies and antibody fragments
such as (Fab').sub.2-, Fab'-, Fab- and Fv-fragments.
[0029] The chimeric G250 antibody was successfully used in clinical
studies for the treatment of renal cell carcinoma patients after
surgery. Even the study has not yet been completed, the treated
patients already show a significant increase in median survival
(more than 15 months) compared to untreated patients (three months)
or patients treated with standard therapy (10-12 months).
[0030] Surprisingly, it was found that in some cases tumor
regression occurred more than six months after start of therapy.
Thus, chimeric G250 antibody and other G250 antibodies are capable
of eliciting a delayed immune response in cancer therapy,
preferably in the treatment of renal cell carcinoma and more
preferably for the treatment of metastases after tumor surgery.
EXAMPLE 1
[0031] Deposit of the G250 hybridoma cell line
[0032] The G250 hybridoma cell line was produced as described in
Example 1 of WO88/08854. Therein a general immunization protocol is
given. Further informations, e.g. a molecular characterization of
the G250 antibody and the G250 hybridoma cell are lacking.
[0033] The G250 hybridoma cell line was deposited according to the
requirements of the Budapest Treaty at DSMZ under the accession No.
DSM ACC 2526 on Sep. 11, 2001.
EXAMPLE 2
[0034] Mapping of the epitope recognized by monoclonal antibody
G250
[0035] From collective experimental evidence it is assumed that the
G250 protein epitope recognized by monoclonal antibody G250
(MAbG250) is conformational, most likely of a non-linear nature.
This assumption is based on the following observations:
[0036] MabG250 does not react with antigen G250 in Western blot
analysis
[0037] Purification of G250 antigen by MAbG250 affinity
chromatography is highly inefficient, with efficiencies decreasing
with increased time needed to perform the purification, suggesting
rapid degradation/unfolding of the G250 epitope, in spite of
optimal conditions to prevent proteolysis.
[0038] Addition of detergents in general lead to decereased G250
detection levels in ELISA
[0039] Truncation of the cDNA encoding for G250 antigen, followed
by transient transfection in G250-negative cells, followed by
immunohistochemical analysis revealed:
1 cDNA construct G250-reactivity nt 1-1500 (aa 1-459), complete +
protein nt 1-1218 (aa 1-406), G250 +/- without transmembrane region
nt 1-1074 (aa 1-358) - nt 1-843 (aa 1-281) - nt 1-672 (aa 1-224) -
nt 1-450 (aa 1-150) -
[0040] It was found that G250-reactivity was lost, even when large
cDNA constructs wee used.
[0041] To further delineate the G250 epitope, the NovaTope system
(Novagen Inc.) was used, a system which ensures expression of all
constructs ligated into this vector, i.e., all possible fragments
are expressed, irrespective of reading frame. This allows
identification of epitopes present in the middle part of a
protein.
[0042] The cDNA encoding for the MN (G250) antigen was digested
with DNAse 1 for 2 hours, resulting in fragments of approximately
50-200 nucleotides encoding polypeptides having a length of about
15-70 amino acids. After dA tailing, the fragments were inserted
into the pScreen T vector, and the ligation mixture was added to
competent E.coli DE3 bacteria for transformation. Bacteria were
plated on selection plates. Bacterial clones were blotted onto
nitrocellulose filters and screened with G250 antibody. In total 7
colonies were identified with MAbG250. G250 reactivity was weak.
After further re-screening, only one bacterial clone appeared to
react with MAbG250, albeit extraordinary very weak, and most likely
due to background staining. Sequence analysis of the clone did not
reveal any G250-sequences, but showed the presence of a truncated
vector. Thus, the staining of the nitrocellulose blot was most
likely the result of non-specific background.
[0043] In a further experiment, cDNA encoding the MN (G250) antigen
was digested with DNAse I, but now fragments of 200-600
nucleotides, encoding polypeptides of approximately 65-200 amino
acids were isolated and cloned into the expression vector and
expressed in bacteria. Separate bacterial colonies were screened
for G250 reactivity.
[0044] Reactivity with G250 was not apparent. Blots were stained
for extended times, after which a faint staining was observed with
6 bacterial isolates. The bacterial isolates only contained a
truncated vector and an unrelated sequence.
[0045] Thus, no partial sequence of the MN antigen having strong
reactivity with MAbG250 could be identified.
[0046] These results strongly suggest that the G250 epitope is
conformational epitope. Further, the G250 epitope on the MN antigen
cannot be characterized by conventional methods even with
considerable efforts.
EXAMPLE 3
[0047] Development of a Chimeric G250 IgG Production Cell Line
[0048] General Strategy
[0049] In order to construct a mouse/human chimeric version of the
murine G250 antibody, the variable region genes for the heavy and
light chains, which determine the binding specificity of the
antibody, were cloned from the G250 murine hybridoma and assembled
in vitro with human constant region genes to generate mouse/human
chimeric antibody genes. Expression of these chimeric genes in the
appropriate cell line resulted in production of a chimeric antibody
with the same binding characteristics as the original murine
antibody, but with approximately 75% of the molecule comprising
human sequences.
[0050] The strategy for cloning the variable regions for the heavy
and light chain genes from the G250 hybridoma was based upon the
linkage in the genome between the variable region and the
corresponding J (joining) region for functionally rearranged (and
expressed) immunoglobulin genes. J region DNA probes can be used to
screen genomic libraries to isolate DNA linked to the J regions;
DNA in the germline configuration (unrearranged) would also
hybridize to J probes, but is not linked to a variable region
sequence and can be identified by restriction enzyme analysis
enzyme analysis of the isolated clones.
[0051] The cloning strategy, therefore, was to isolate variable
regions from rearranged heavy and light chain genes using JH and JK
probes. In addition, to assist in identifying and characterizing
the correct genomic clones, cDNA clones corresponding to the heavy
and light chain variable regions were also obtained from the mRNA
produced in the G250 hybridoma. Those genomic clones that matched
the G250 cDNA sequences were cloned into expression vectors
containing human constant regions and transfected into mouse
myeloma cells to determine if an antibody was produced. The
antibody from producing cells was then tested for binding
specificity compared to the murine G250 antibody.
[0052] Cloning of G250 VH and VL cDNA
[0053] Total RNA was isolated from G250 hybridoma cell and used to
generate specific VH and VL cDNA clones. First strand cDNA
synthesis was performed using oligonucleotide primers specific for
the murine kappa and IgG constant regions. After dG tailing, second
strand synthesis was performed using C-tailed oligonucleotide
primers. The heavy and light chain variable regions were amplified
via polymerase chain reaction using specific 5' and 3' primers, and
the amplification products were cloned into the plasmid vector
pUC19. VH and VL clones were subjected to DNA sequence analysis to
establish the base sequences of the putative G250 heavy and light
chain variable regions. The sequencing results are shown in FIG.
1.
[0054] Cloning of the G250 Variable Region Genes:
[0055] To clone the variable region genes, high molecular weight
genomic DNA was isolated from G250 hybridoma cells by treatment of
isolated nuclei with SDS and proteinase K followed by two phenol
extractions and an ethanol precipitation.
[0056] Southern blot analysis using a J region probe for the heavy
chain locus suggested that the G250 heavy chain was contained on a
2.3 kilobase (Kb) Eco RI DNA fragment. Accordingly, the Eco RI
fragments from hybridoma DNA were fractionated on a 0.8% agarose
gel and the size range of approximately 2-3 Kb fragments was eluted
from the gel and ligated to the vector arms of the lambda
bacteriophage vector Zap II (Stratagene, La Jolla Calif., USA). The
ligation was packaged into phage particles in vitro using Gigapack
Gold (Stratagene) and plated on E.coli LE392 cells at a density of
approximately 20.000 plaques per 150 mm plate. The plaques were
transferred to nitrocellulose filters and probed with a
.sup.32P-labeled DNA probe (a 2.0 Kb Eco RI-BamHI fragment
containing the murine J3 and J4 exons).
[0057] For the light chain G250 variable region gene, a Southern
blot analysis using a murine J region probe from the kappa locus
indicated that the correct gene was located on a 5.5 Kb HindIII
fragment. Accordingly, G250 hybridoma DNA was digested with HindIII
and DNA fragments of 5-6 Kb were isolated from a 0.8% agarose gel
and ligated to the arms of the bacteriophage lambda vector Charon
27. The ligated DNA was packaged into phage particles in vitro
using Gigapack Gold (Stratagene), and plated on E.coli LE392 cells
at a density of approximately 20.000 plaques per 150 mm plate. The
plaques were transferred to nitrocellulose filters and probed with
a .sup.32P-labeled DNA probe (a 2.7 Kb HindIII fragment containing
all five J kappa exons).
[0058] Positive clones for the heavy and light chain genes were
isolated following at least 3 rounds of plaque purification using
the J region probes to verify hybridization to the phage DNA at
each stage of purification. Purified DNA from the isolated phage
clones for the heavy and light genes was digested with EcoRI (heavy
chain) or HindIII (light chain) and fractionated on agarose gels.
The appropriate size fragments (2.3 Kb for the heavy chain and 5.5
Kb for the light chain) were isolated from the gels, and subcloned
into the plasmid vector pUC19. These subcloned DNA fragments were
shown by restriction endonuclease mapping and DNA sequence analysis
to contain variable region antibody genes that matched the
structures of the cDNA clones originally obtained from the G250
hybridoma.
[0059] Expression Plasmids
[0060] The 2.3 Kb Eco RI heavy chain variable region fragment was
cloned into a suitable expression vector which contains the human
G1 constant region and a gene which confers resistance to a
selectable marker in mammalian cells. The 5.5. Kb HindIII light
chain fragment was cloned into a suitable expression vector which
contains the human kappa constant region and a gene conferring
resistance to a selectable marker in mammalian cells. The presence
of the cloned fragments and their orientation in the expression
vectors was determined by restriction enzyme mapping. The basic
vectors have been used previously for the construction of chimeric
antibodies (Sun, L. et al., (1987) PNAS 84, p. 214; Knight et al.,
(1993), Molecular Immunology 30, p. 1443-1453). Expression of the
chimeric antibody genes is achieved using the natural
immunoglobulin promoters present upstream of the cloned variable
regions; downstream regulatory signals are provided by the elements
associated with the constant region genes.
[0061] Expression of the G250 Chimeric Antibody
[0062] The heavy and light chain expression vectors were used to
co-transfect a non-producing mouse myeloma cell line using the
technique of electroporation. An ELISA assay was used to screen
clones for secreted antibody containing a human Fc region, and the
highest producer (cG250) was chosen for further
characterization.
[0063] The chimeric antibody was purified by chromatography on
protein A-sepharose, and analyzed in a competition assay to verify
that the antibody has the correct specificity. The cG250 antibody
was found to be equally effective in competing with
.sup.125I-labelled murine G250 for binding to A704 renal cell
carcinoma cells (which express the G250 antigen) as the unlabeled
murine G250 antibody. The chimeric G250 antibody, therefore, is
similar in its binding characteristics to the original murine G250
antibody.
EXAMPLE 4
[0064] Use of chimeric G250 antibody in a clinical study
[0065] Administration Protocol
[0066] Renal cell carcinoma patients, having metastases after
surgery, were treated by administering 50 mg chimeric G250 antibody
via 30 min. infusion once per week for 12 weeks.
[0067] Efficacy Conclusions:
[0068] In the present study durable stable disease for over six
months was achieved in eight out of 32 patients (25%) of the
patients. The median time to progression for all patients was 16
weeks (mean 26,67 weeks) with a range from 4 to 70 weeks. As of
December 2001, the date of cut off, five patients are still free of
progression (51+, 56+, 60+, 64+, and 70+ weeks).
[0069] The importance of these findings is supported by the fact
that most of these patients had documented progressive disease, for
another two patients it is assumed that they were progressive at
study entry. In addition, three of these patients were refractory
to prior cytokine- and chemotherapy or had relapsed several years
after cytokine treatment. Four patients had no prior therapy and
were treated with the study drug immediately after diagnosis of
metastases. At study entry three of these patients had a Karnofsky
performance status (KPS) of 80%, two a KPS of 90%. Hemoglobin (Hgb)
was below 10 g/dL in 5 patients. The median performance status of
90% (mean 91%) is identical to the group of patients who have not
responded. The median Hgb of 9.8 g/dL (mean 10.97 g/dL) is also
relatively low.
[0070] One patient achieved a complete objective remission. The
objective response occurred late, more than six months after start
of study therapy. Another patient experienced a relevant reduction
of 59% in size of his target lesions. The response of both patients
is ongoing at week 64 and 70, respectively, as evaluated in
December 2001. The tumor regression occurred late, more than six
months after start of study therapy. An explanation for the late
response may be that the treatment duration with iv injections of
the chimeric antibody was relatively short and a delayed immune
response unrelated to ADCC developed.
[0071] The response is durable at more than one year and is still
ongoing December 2001. The overall rate of clinical benefit (at
least more than six months or objective response) is 25%. In
addition it should be noted that at six months after start of study
treatment, 87.5% (28/32) of the patients were still alive.
[0072] At the end of November 2001, an estimation of median
survival was calculated to be at least 13.5 months.
[0073] At the end of January 2002, an estimation of median survival
was calculated to be at least 15 months. This is significantly
higher than the median survival of untreated patients (three
months) and the median survival of patients treated with an FDA
approved standard therapy, i.e. administration of high dose
interleukin 2 (10-12 months).
[0074] Thus, it becomes evident that chimeric antibody G250 is a
suitable therapeutic agent for the treatment of renal cell
carcinoma. In a preferred embodiment the treatment comprises a
surgical removal of the main tumor and a subsequent administration
of G250, in order to eliminate metastases distributed throughout
the body.
Sequence CWU 1
1
2 1 357 DNA Artificial Sequence mouse/human chimeric antibody gene
1 gac gtg aag ctc gtg gag tct ggg gga ggc tta gtg aag ctt gga ggg
48 Asp Val Lys Leu Val Glu Ser Gly Gly Gly Leu Val Lys Leu Gly Gly
1 5 10 15 tcc ctg aaa ctc tcc tgt gca gcc tct gga ttc act ttc agt
aac tat 96 Ser Leu Lys Leu Ser Cys Ala Ala Ser Gly Phe Thr Phe Ser
Asn Tyr 20 25 30 tac atg tct tgg gtt cgc cag act cca gag aag agg
ctg gag ttg gtc 144 Tyr Met Ser Trp Val Arg Gln Thr Pro Glu Lys Arg
Leu Glu Leu Val 35 40 45 gca gcc att aat agt gat ggt ggt atc acc
tac tat cta gac act gtg 192 Ala Ala Ile Asn Ser Asp Gly Gly Ile Thr
Tyr Tyr Leu Asp Thr Val 50 55 60 aag ggc cga ttc acc att tca aga
gac aat gcc aag aac acc ctg tac 240 Lys Gly Arg Phe Thr Ile Ser Arg
Asp Asn Ala Lys Asn Thr Leu Tyr 65 70 75 80 ctg caa atg agc agt ctg
aag tct gag gac aca gcc ttg ttt tac tgt 288 Leu Gln Met Ser Ser Leu
Lys Ser Glu Asp Thr Ala Leu Phe Tyr Cys 85 90 95 gca aga cac cgc
tcg ggc tac ttt tct atg gac tac tgg ggt caa gga 336 Ala Arg His Arg
Ser Gly Tyr Phe Ser Met Asp Tyr Trp Gly Gln Gly 100 105 110 acc tca
gtc acc gtc tcc tca 357 Thr Ser Val Thr Val Ser Ser 115 2 321 DNA
Artificial Sequence mouse/human chimeric antibody gene 2 gac att
gtg atg acc cag tct caa aga ttc atg tcc aca aca gta gga 48 Asp Ile
Val Met Thr Gln Ser Gln Arg Phe Met Ser Thr Thr Val Gly 1 5 10 15
gac agg gtc agc atc acc tgc aag gcc agt cag aat gtg gtt tct gct 96
Asp Arg Val Ser Ile Thr Cys Lys Ala Ser Gln Asn Val Val Ser Ala 20
25 30 gtt gcc tgg tat caa cag aaa cca gga caa tct cct aaa cta ctg
att 144 Val Ala Trp Tyr Gln Gln Lys Pro Gly Gln Ser Pro Lys Leu Leu
Ile 35 40 45 tac tca gca tcc aat cgg tac act gga gtc cct gat cgc
ttc aca ggc 192 Tyr Ser Ala Ser Asn Arg Tyr Thr Gly Val Pro Asp Arg
Phe Thr Gly 50 55 60 agt gga tct ggg aca gat ttc act ctc acc att
agc aat atg cag tct 240 Ser Gly Ser Gly Thr Asp Phe Thr Leu Thr Ile
Ser Asn Met Gln Ser 65 70 75 80 gaa gac ctg gct gat ttt ttc tgt caa
caa tat agc aac tat ccg tgg 288 Glu Asp Leu Ala Asp Phe Phe Cys Gln
Gln Tyr Ser Asn Tyr Pro Trp 85 90 95 acg ttc ggt gga ggc acc aag
ctg gaa atc aaa 321 Thr Phe Gly Gly Gly Thr Lys Leu Glu Ile Lys 100
105
* * * * *