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Selection and affinity maturation of recombinant phage antibodies to tumour-associated HLA antigen/peptide complexes

Objective



The prospects for cancer immunotherapy rely on the identification of tumour-associated cell surface antigens and their specific recognition, e.g. by cytotoxic T lymphocytes (CTL). Antigens recognised by tumour-specific CTL consist of peptides derived from endogenous proteins and presented by human major histocompatibility (HLA) class I molecules, ideally only on tumour cells. Several such polypeptides have been described in the past two years, e.g. in melanomas. Another target is the tumour suppressor p53 protein, overexpressed in more than 50% of all human malignancies and recognized by CTL in the context of HLA-A2, the most frequent HLA class I allele. However, despite their exquisite specificity, CTL have a number of shortcomings in comparison to antibodies, in particular with respect to production, handling and general applicability. These difficulties may now be overcome by replacing tumour-specific CTL with recombinant phage antibodies recognizing HLA/peptide complexes. With phage display, reagents can principally be made completely in-vitro, by-passing the immune system and the immunization procedure, and allowing in-vitro tailoring of the specificity and affinity of the antibody. However, despite the availability of efficient screening procedures, in-vitro affinity maturation strategies are still in their infancy. They still need considerable improvement to allow maturation of selected antibodies in batch rather than on an individual basis.
Therefore, this project seeks to identify recombinant antibodies directed against certain HLA class I molecules complexed with peptides derived from tumour-associated antigens. Molecular immunological technologies will then be employed to improve the affinity of selected reagents. This will lead to the development and exploitation of commercially interesting recombinant reagents with diagnostic and therapeutic potential.
The detailed objectives of this project are as follows:
1. Preparation of HLA-Al,-A2, and -B44 molecules complexed with various tumour-derived peptides.
2. Assessment of structural and functional integrity of HLA/peptide complexes. 3. Selection of recombinant phage antibodies recognizing these HLA/peptide complexes.
4. Affinity maturation of already available single chain Fv reagents against HLA/peptide complexes.
5. Assessment of the diagnostic potential of selected recombinant antibodies. 6. Assessment of the therapeutic potential of selected recombinant antibodies using SCID mice.
To meet these objectives, five European groups with expertise in complementing areas of molecular immunology will cooperate. The commercial significance of phage library-derived synthetic antibodies recognizing tumour specific HLA/peptide complexes relates not only to their value as reagents for diagnostic purposes but also to their potential for successful therapeutic application in several common human malignancies.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Humboldt-Universität zu Berlin
Address
130,Spandauer Damm
14050 Berlin
Germany

Participants (4)

Academisch Ziekenhuis bij de Rijksuniversiteit van Maastricht
Netherlands
Address
25,Peter Debyelaan
6202 AZ Maastricht
CHRISTIAN DE DUVE INSTITUTE OF CELLULAR PATHOLOGY
Belgium
Address
Avenue Hippocrate 74
1200 Bruxelles
Danish Cancer Society
Denmark
Address
70,Ndr. Frihavnsgade 70
2100 København
Danmarks Farmaceutiske Højskole
Denmark
Address
160,Jagtvejen
2100 København Ø