Abstract A039: Accurate identification and prioritization of candidate neoantigens from cancer exome sequencing

Abstract

Abstract Somatic, nonsynonymous genetic alterations present in cancer can lead to the formation of novel protein sequences and thus production of immunogenic “non-self” neoantigens. Those neoantigens with sufficient expression will be processed and presented on MHC molecules, subsequently inducing a tumor-specific T cell response. Emerging data from clinical studies suggest that neoantigen load and composition is associated with the efficacy of some immunotherapies. As neoantigens play central a role in the cancer-immunity cycle, it is critical to identify the most potent immunogenic neoantigens effectively and accurately. Here we have leveraged highly accurate cancer whole exome (WES) analyses from FFPE tumor tissue with a state-of-the-art analysis protocol to identify and prioritize candidate neoantigens most likely to promote an immune response. ImmunoSelect-R utilizes somatic variants from WES to ensure detection of true somatic peptides and minimize false positives, and provides accurate HLA typing from whole exome sequencing data with >99.9% sensitivity and specificity. When applied to a set of experimentally validated neoantigens, ImmunoSelect correctly classified 18 out of 19 as strong neoantigen candidates, suggesting a sensitivity of greater than 90%. Moreover, in a small set of 10 patients, ImmunoSelect consistently ranked experimentally validated neoantigens within top 20% of all neoantigen candidates derived from whole exome sequencing. In summary, ImmunoSelect is able to identify and prioritize candidate neoantigens from cancer exome sequencing results effectively and accurately, enabling personalized cancer vaccine development, adoptive T-cell transfer, and prediction of response to checkpoint inhibitors Citation Format: James White, John Simmons, Sam Angiuoli, Mark Sausen, Sian Jones, Lisa Kann, Manish Shukla, Maria Sevdali, Victor Velculescu, Luis Diaz, Theresa Zhang. Accurate identification and prioritization of candidate neoantigens from cancer exome sequencing [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A039.