Proteins belonging to the Bcl-2 family and fragments thereof, and their use in cancer patients

#The present invention relates generally to the field of cancer prophylaxis and therapy. In particular there are provided isolated apoptosis regulating proteins or peptide fragments thereof that are capable of eliciting anti-cancer immune responses. Specifically, the use of such proteins belonging to the Bcl-2 protein family and immunogenic peptide fragments hereof in cancer treatment, diagnosis and prognosis is provided.

#The development of resistance by cancer cells to a wide variety of chemotherapeutic agents poses a major obstacle in the successful treatment of cancer. Drug resistance is observed in a broad range of cancer cell types. Many mechanisms contribute to drug resistance, including drug inactivation, extrusion of the drug by cell membrane pumps, mutations of drug targets, and failure to initiate apoptosis. Prevention of apoptosis can result from a variety of conditions, including retention of the mitochondrial membrane potential and cytokine stimulation.

#The search for proteins responsible for drug-resistant phenotypes has implicated the antiapoptotic molecule Bcl-2. Overexpression of Bcl-2 plays a role in the development of drug resistance in leukaemia and other apoptosis-prone tumours and, consequently, a poor prognosis in various human cancers. Bcl-2 belongs to a family of proteins, the Bcl-2 family, the members of which regulate apoptosis. The family includes both proapoptotic and antiapoptotic members. Although a precise understanding of how Bcl-2 exerts its antiapoptotic effects remains elusive, it has been found to be overexpressed in many cancers including lung, colorectal, prostate, and breast cancers as well as in leukaemia's and lymphomas.

#The invention will now be illustrated by the following, non-limiting examples and the drawings wherein

#FIG. 1 shows identification of HLA-A2 binding peptides from Bcl-2. Class I MHC heavy chain bands were quantified using a Phosphorimager. The amount of stabilised HLA-A2 heavy chain is directly related to the binding affinity of the added peptide. The binding of the HLA-A2-restricted positive control peptide HIV Pol476 (black square) was compared with the peptides Bcl172 (black triangle), Bcl180 (black circle), and Bcl200 (white circle) and

#FIG. 2 illustrates T-cell response against the peptides Bcl172, Bcl180, Bcl208, and Bcl214. PBL from 15 breast cancer patients were analysed. T-lymphocytes were stimulated once with peptide before plated at 105 cells per well in triplicates either without or with peptide. The average number of peptide specific spots (after subtraction of spots without added peptide) was calculated for each patient using the ImmunoSpot® Series 2.0 Analyzer (CTL Analyzers, LLC, Cleveland, US).

#Immune responses against Bcl-2 in breast cancer patients

#Materials and Methods

#1. Patients