Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Recombinant dna technique included in method of making a...
Reexamination Certificate
1998-10-29
2001-08-21
Huff, Sheela (Department: 1642)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Recombinant dna technique included in method of making a...
C435S326000, C435S328000, C435S344100, C530S387300, C530S388800, C530S388850
Reexamination Certificate
active
06277599
ABSTRACT:
The present invention relates to a novel anti-CEA monoclonal antibody (named “806.077 antibody” or “806.077 Ab” herein) useful for the diagnosis and therapy of cancer.
It is established that the transformation of normal tissue cells to tumour cells is associated with a change in structure on the cell surface. Altered cell surface structures can serve as antigens and the tumour modified structures represent a type of so-called tumour-associated antigen (see for example Altered Glycosylation in Tumour Cells, Eds. Reading, Hakamori and Marcus 1988, Arthur R. Liss publ.). Such antigens may be exploited for example by the generation of monospecific antibodies using hybridoma technology as is presently well established after being first described by Kohler and Milstein (Nature, 256, 495-497, 1975).
One tumour-associated antigen is CEA (Carcinomembryonic Antigen) as first described by Gold and Freedman, J Exp Med, 121 439, 1965. This antigen is present on the tumour cell surface and can also be demonstrated in blood serum.
The concept of using antibodies to target tumour associated antigens in the treatment of cancer has been appreciated for some time (Herlyn et.al. (1980) Cancer Research 40 717). Antibodies may be used to target various chemical and biological agents to the tumour and such conjugates have been particularly successful in forming the basis for many methods of both in vitro and in vivo diagnosis. The use of immunoconjugates in the therapy of cancer is also promising (Lord et al.(1985) Trends in Biotechnology 3, 175; Vitetta et al (1987) Science 238, 1098). This approach is technically more demanding than diagnostic applications and requires that tumour associated antigens which are targetted in such immunotherapeutic approaches, are highly tumour specific and not expressed at significant levels in vital human tissues. Whilst not wishing to be bound by theoretical considerations, as well as the property of having specific tumour associated tissue distribution, for some applications it is desirable that the antibody remain at the cell surface after antigen binding rather than being quickly internalised. For example in ADEPT (antibody directed enzyme prodrug therapy, see U.S. Pat. Nos. 4,975,278 and 5,405,990) it is believed to be preferred that the antibody remain at the cell surface to facilitate prodrug activation by antibody-enzyme conjugate.
Antibody conjugates also have application in tumour immunotherapy. The following few paragraphs set out the scientific background for this application. In order to respond to an immune stimulus, T-cells require two signals. One such signal is provided by recognition of MHC displayed peptides by the T-cell receptor (TCR). It has been demonstrated however that TCR stimulation alone results in T-cell unresponsiveness or anergy and a second or co-stimulatory signal is required to stimulate specific T-cell activation and proliferation (reviewed by Schwartz R. H. J.Exp.Med., 1996, 184, 1-8). Upon receiving both signals, the resulting cytotoxic T-cells mediate the immune response by killing the target cells. A number of potential co-stimulatory molecules have been identified (eg B7, ICAMs, LFA-1 and 3, CD40, CD70 and CD24, reviewed by Galea-Lauri J. et al Cancer Gene Therapy, 1996, 3, 202-213). The major co-stimulatory function appears to be provided by the related molecules B7.1 (also called CD80) and B7.2 (also called CD86) which can interact with two receptors, CD28 and CTLA-4 (Hellstrom K. E. et al Immunol. Rev., 1995, 145, 123-145 and Lenschow D. J. et al Ann.Rev.Immunol., 1996, 14, 233-258). B7.1 and B7.2 are expressed on antigen presenting cells (APC) such as dendritic cells whereas CD28 and CTLA-4 are present on T-cells. B7.2 appears to be constitutively expressed on the surface of APCs but after contact with a T-cell, expression of B7.1 is up-regulated. Analogously, CD28 is expressed on T-cells but after activation is down-regulated and replaced by CTLA-4 expression. The stimulation of CD28 and CTLA-4 by B7.1 and B7.2 represents a complex pattern of signalling which controls not only the activation of the T-cell, but the subsequent control of proliferation to modulate the immune-response (Greene J. et al J.Biol.Chem., 1996, 271, 26762-26771). This phenomenon may explain the sometimes conflicting data reported by workers studying these co-stimulatory molecules.
In cancer, tumour infiltrating lymphocytes have been identified but the lack of immune-response to the tumour may be due to T-cell anergy. Tumour cells can display specific or selective antigens on their surface but lack B7.1/B7.2 allowing them to escape immune surveillance. Indeed, in vivo experiments have demonstrated that B7.1/B7.2 transfected tumour cells are less tumourigenic than untransfected cells from the same line and that the transfected cells are capable of inducing protective immunity against rechallenge with parental cells (Townsend S. E. and Allison J. P., 1993, Science, 259, 368-370). This demonstrates that once stimulated, the immune response can become B7.1/B7.2 independent. Hellstrom has proposed that expression of B7.1/B7.2 in tumour cells by gene therapy has the potential to stimulate a host reponse which can reduce or eliminate the disease. Gajewski (J.Immunol., 1996, 156, 465-472) and Matulonis et al (J.Immunol., 1996, 156, 1126-1131) have reported that B7.1 is superior to B7.2 in the activation of T-cells. The use of B7.1 in solution (as a fusion with antibody constant domains) is reported to provide only modest co-stimulation to T-cells receiving TCR stimulation via an independent source (Linsley P.S. et al J.Exp.Med., 1991, 173, 721-730).
There is a need for further and improved anti-CEA antibodies useful in cancer diagnosis and therapy.
The present invention is based on the discovery of a novel anti-CEA antibody termed 806.077 antibody herein.
According to one aspect of the present invention there is provided an anti-CEA antibody comprising complementarity determining regions (CDRs) in which the CDRs have the following sequences:
a) heavy chain
CDR1 DNYMH (SEQ ID NO: 29)
CDR2 WIDPENGDTE YAPKFRG (SEQ ID NO: 31)
CDR3 LIYAGYLAMD Y(SEQ ID NO: 32);
b) light chain
CDR1 SASSSVTYMH (SEQ ID NO: 26)
CDR2 STSNLAS (SEQ ID NO: 27)
CDR3 QQRSTYPLT (SEQ ID NO: 28).
The CDRs or complementarity determining regions are those sequences within the hypervariable loops of antibody variable domains which are believed to be critical in determining the specificity of the antigen-antibody interaction (Kabat, E. A., Lu, T. T., Reid-Miller, M., Perry, H. M. & Gottesman, K. S. (1987). Sequences of Proteins of Immunological Interest. 4th edition. Washington D.C.: United States Dept. of Health and Human Services; the reader is also referred to this reference for details of Kabat antibody residue numbering). CDRs a defined herein however include framework residues where these contribute to binding. For the 806.077 antibody the CDRs were determined by homology with the hypervariable sequences of other murine antibodies. In this specification the terms “VK” and “VH” mean variable regions of the light and heavy antibody chains respectively. Anatomy of the antibody molecule has been reviewed by Padlan (1994) in Molecular Immunology 31, 169-217.
The Light Chain CDRs are:
VK CDR1 Kabat residues 24-34 inclusive, SASSSVTYMH (SEQ ID NO: 26);
VK CDR2 Kabat residues 50-56 inclusive, STSNLAS (SEQ ID NO: 27);
VK CDR3 Kabat residues 89-97 inclusive, QQRSTYPLT (SEQ ID NO: 28);
The Heavy Chain CDRs are:
VH CDR1 Kabat residues 31-35B inclusive, DNYMH (SEQ ID NO: 29);
preferred VH CDR1 Kabat residues are no. 27-35B inclusive, FNIKDNYMH (SEQ ID NO: 30);
VH CDR2 Kabat residues 50-65 inclusive, WIDPENGDTE YAPKFRG (SEQ ID NO: 31)
VH CDR3 Kabat residues 95-102 inclusive, LIYAGYLAMD Y (SEQ ID NO: 32); and
preferred VH CDR3 Kabat residues are no. 93-102 inclusive, HVLIYAGYLA MDY (SEQ ID NO: 33).
Preferably binding affinity for CEA antigen is at least 10E-5M, more preferably binding affinity for CEA is at least 10E-6M, more preferably binding affinity for CEA is at least 10E-7M, more preferably binding
Copley Clive Graham
Edge Michael Derek
Emery Stephen Charles
Helms Larry R.
Huff Sheela
Rothwell Figg Ernst & Manbeck
Zeneca Limited
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