A degenerate HLA-DR epitope pool of HER-2/neu reveals a novel in vivo immunodominant epitope, HER-2/neu88-102

Original Articles
2010
Clinical Cancer Research 16(3): p. 825-34. 2010
Karyampudi, L., Formicola, C., Erskine, C. L., Maurer, M. J., Ingle, J. N., Krco, C. J., Wettstein, P. J., Kalli, K. R., Fikes, J. D., Beebe, M., Hartmann, L. C., Disis, M. L., Ferrone, S., Ishioka, G., Knutson, K. L.
Description / Abstract: 

PURPOSE:

Over the past two decades, there has been significant interest in targeting HER-2/neu in immune-based approaches for the treatment of HER-2/neu+ cancers. For example, peptide vaccination using a CD8 T cell-activating HER-2/neu epitope (amino acids 369-377) is an approach that is being considered in advanced phase clinical trials. Studies have suggested that the persistence of HER-2/neu-specific CD8 T cells could be improved by incorporating human leukocyte antigen (HLA) class II epitopes in the vaccine. Our goal in this study was to identify broad coverage HLA-DR epitopes of HER-2/neu, an antigen that is highly expressed in a variety of carcinomas.

EXPERIMENTAL DESIGN:

A combination of algorithms and HLA-DR-binding assays was used to identify HLA-DR epitopes of HER-2/neu antigen. Evidence of preexistent immunity in cancer patients against the identified epitopes was determined using IFN-gamma enzyme-linked immunosorbent spot (ELIspot) assay.

RESULTS:

Eighty-four HLA-DR epitopes of HER-2/neu were predicted, 15 of which had high binding affinity for > or =11 common HLA-DR molecules. A degenerate pool of four HLA-DR-restricted 15-amino acid epitopes (p59, p88, p422, and p885) was identified, against which >58% of breast and ovarian cancer patients had preexistent T-cell immunity. All four epitopes are naturally processed by antigen-presenting cells. Hardy-Weinberg analysis showed that the pool is useful in approximately 84% of population. Lastly, in this degenerate pool, we identified a novel in vivo immunodominant HLA-DR epitope, HER-2/neu(88-102) (p88).

CONCLUSION:

The broad coverage and natural immunity to this epitope pool suggests potential usefulness in HER-2/neu-targeting, immune-based therapies such as vaccines.

PubMed ID: 
20103660