Chemistry: natural resins or derivatives; peptides or proteins; – Proteins – i.e. – more than 100 amino acid residues – Blood proteins or globulins – e.g. – proteoglycans – platelet...
Reexamination Certificate
1999-05-20
2003-01-28
Bansal, Geetha P. (Department: 1642)
Chemistry: natural resins or derivatives; peptides or proteins;
Proteins, i.e., more than 100 amino acid residues
Blood proteins or globulins, e.g., proteoglycans, platelet...
C530S387300, C530S387700, C530S388100, C530S388150, C530S388200, C530S388220, C530S388240, C530S388800, C530S388850, C530S391100, C530S391300, C530S391700, C530S391900, C530S395000
Reexamination Certificate
active
06512097
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention pertains to the fields of immunodiagnostics and immunotherapeutics. In particular, this invention pertains to the discovery of novel human antibodies that specifically bind to c-erbB-2, and to chimeric molecules containing these antibodies.
Conventional cancer chemotherapeutic agents cannot distinguish between normal cells and tumor cells and hence damage and kill normal proliferating tissues. One approach to reduce this toxic side effect is to specifically target the chemotherapeutic agent to the tumor. This is the rationale behind the development of immunotoxins, chimeric molecules composed of an antibody either chemically conjugated or fused to a toxin that binds specifically to antigens on the surface of a tumor cell thereby killing or inhibiting the growth of the cell (Frankel et al.
Ann. Rev. Med.,
37: 127 (1986)). The majority of immunotoxins prepared to date, have been made using murine monoclonal antibodies Nabs) that exhibit specificity for tumor cells. Immunotoxins made from Mabs demonstrate relatively selective killing of tumor cells in vitro and tumor regression in animal models (id.).
Despite these promising results, the use of immunotoxins in humans has been limited by toxicity, immunogenicity and a failure to identify highly specific tumor antigens (Byers et al.
Cancer Res.,
49: 6153). Nonspecific toxicity results from the failure of the monoclonal antibody to bind specifically and with high affinity to tumor cells. As a result, nonspecific cell killing occurs. In addition, the foreign immunotoxin molecule elicits a strong immune response in humans. The immunogenicity of the toxin portion of the immunotoxin has recently been overcome by using the human analog of RNase (Rybak et al.
Proc. Nat. Acad. Sci., USA,
89: 3165 (1992)). The murine antibody portion, however, is still significantly immunogenic (Sawler et al.,
J. Immunol.,
135: 1530 (1985)).
Immunogenicity could be avoided and toxicity reduced if high affinity tumor specific human antibodies were available. However, the production of human monoclonal antibodies using conventional hybridoma technology has proven extremely difficult (James et al.,
J. Immunol. Meth.,
100: 5 (1987)). Furthermore, the paucity of purified tumor-specific antigens makes it necessary to immunize with intact tumor cells or partially purified antigen. Most of the antibodies produced react with antigens which are also common to normal cells and are therefore unsuitable for use as tumor-specific targeting molecules.
SUMMARY OF THE INVENTION
This invention provides novel human antibodies that specifically bind to the extracellular domain of the c-erbB-2 protein product of the HER2
eu oncogene. This antigen (marker) is overexpressed on many cancers (e.g. carcinomas) and thus the antibodies of the present invention specifically bind to tumor cells that express c-erbB-2.
In a preferred embodiment, the antibody is a C6 antibody derived from the sFv antibody C6.5. The antibody may contain a variable heavy chain, a variable light chain, or both a variable heavy and variable light chain of C6.5 or its derivatives. In addition the antibody may contain a variable heavy chain, a variable light chain or both a variable heavy and variable light chain of C6.5 in which one or more of the variable heavy or variable light complementarity determining regions (CDR1, CDR2 or CDR3) has been altered (e.g., mutated). Particularly preferred CDR variants are listed in the specification and in Examples 1, 2 and 3. Particularly preferred C6 antibodies include C6.5, C6ML3-14, C6L-1 and C6MH3-B1. In various preferred embodiments, these antibodies are single chain antibodies (sFv also known as scFv) comprising a variable heavy chain joined to a variable light chain either directly or through a peptide linker. Other preferred embodiments of the C6 antibodies and C6.5, C6ML3-14, C6L1, and C6MH3-B1, in particular, include Fab, the dimer (Fab′)
2
, and the dimer (sFv′)
2
. Particularly preferred (sFv′)
2
dimers are fusion proteins where the Sfv′ components are joined through a peptide linkage or through a peptide (G,S). Still other preferred C6 antibodies include an antibody selected from the group consisting of an antibody having a V
L
domain with one of the amino acid sequences shown in Table 10, an antibody having a V
H
domain with one of the amino acid sequences shown in Table 12, an antibody having a V
L
CDR3 domain having one of the amino acid sequences shown in Tables 4, 15, and 16, and an antibody having a V
H
CDR3 domain having one of the amino acid sequences shown in Tables 13 and 14. Other preferred embodiments are to be found replete throughout the specification.
In a particularly preferred embodiment, the C6 antibody has a K
d
ranging from about 1.6×10
−8
to about 1×10
−12
M in SK-BR-3 cells using Scatchard analysis or as measured against purified c-erbB-2 by surface plasmon resonance in a BIAcore.
In another embodiment the present invention provides for nucleic acids that encode any of the above-described C6 antibodies. The invention also provides for nucleic acids that encode the amino acid sequences of C6.5, C6ML3-14, C6L1, C6MH3-B1, or any of the other amino acid sequences encoding C6 antibodies and described in Example 1, 2 or 3. In addition this invention provides for nucleic acid sequences encoding any of these amino acid sequences having conservative amino acid substitutions.
In still another embodiment, this invention provides for proteins comprising one or more complementarity determining regions selected from the group consisting of the complementarity determining regions of Tables 10, 12, 13, 14, 15, and 16 and of any of the examples, in particular of Examples 1, 2 or 3. Other particularly preferred antibodies include any of the antibodies expressed by the clones described herein.
In still yet another embodiment, this invention provides for cells comprising a recombinant nucleic acid which is any of the above described nucleic acids.
This invention also provides for chimeric molecules that specifically bind a tumor cell bearing c-erbB-2. The chimeric molecule comprises an effector molecule joined to any of the above-described C6 antibodies. In a preferred embodiment, the effector molecule is selected from the group consisting of a cytotoxin (e.g. PE, DT, Ricin A, etc.), a label, a radionuclide, a drug, a liposome, a ligand, an antibody, and an antigen binding domaine). The C6 antibody may be chemically conjugated to the effector molecule or the chimeric molecule may be expressed as a fusion protein.
This invention provides for methods of making C6 antibodies. One method proceeds by i) providing a phage library presenting a C6.5 variable heavy chain and a multiplicity of human variable light chains; ii) panning the phage library on c-erbB-2; and iii) isolating phage that specifically bind c-erb2. This method optionally further includes iv) providing a phage library presenting the variable light chain of the phage isolated in step iii and a multiplicity of human variable heavy chains; v) panning the phage library on c-erbB-2; and vi) isolating phage that specifically bind c-erbB-2.
Another method for making a C6 antibody proceeds by i) providing a phage library presenting a C6.5 variable light chain and a multiplicity of human variable heavy chains; ii) panning the phage library on c-erbB-2; and iii) isolating phage that specifically bind c-erbB-2.
Yet another method for making a C6 antibody involves i) providing a phage library presenting a C6.5 variable light and a C6.5 variable heavy chain encoded by a nucleic acid variable in the sequence encoding CDR1, CDR2 or CDR3 such that each phage displays a different CDR; ii) panning the phage library on c-erbB-2; and isolating the phage that specifically bind c-erbB-2.
This invention also provides a method for impairing growth of tumor cells bearing c-erbB-2. This method involves contacting the tumor with a chimeric molecule comprising a cytotoxin attached to a human C6 antibody that specifica
Marks James D.
Schier Robert
Bansal Geetha P.
Hunter Tom
Quine Intellectual Property Law Group
The Regents of the University of California
LandOfFree
High affinity human antibodies to tumor antigens does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with High affinity human antibodies to tumor antigens, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High affinity human antibodies to tumor antigens will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3007411