Abstract PO030: A Novel T-cell Population Expressing the Ectoenzymes CD38 and CD39 is Associated with Melanoma Patient Non-Response to Immunotherapy

Cancer immunotherapy has emerged as one of the most potent therapeutic tools in treating melanoma and a variety of other malignancies. Immunotherapy includes inhibition of the modulators of T cell antitumor function, the immune checkpoints, by using antibodies against them. In advanced melanoma patients, immune checkpoint inhibitors ipilimumab (IPI) and nivolumab (NIVO) have had unprecedented efficacy. Although many patients respond well to this therapy, many patients remain unresponsive. The mechanism underlying treatment failures remains poorly understood. Using a novel high-dimensional flow cytometry analysis methodology, CytoBrute, we found that in the cohort of advanced melanoma patients receiving sequential NIVO-IPI, high baseline levels of a novel immunophenotype, CD4+CD38+CD39+CD127-GARP- T-cells (median frequency 0.3%), was associated with poor outcomes (disease progression p=0.008, and decreased overall survival p Citation Format: Ankita Mitra, David M. Woods, Anjali Rao, Andressa S. Laino, Aidan Winters, Itai Yanai, Pratip K. Chattopadhyay, Jeffrey S. Weber. A Novel T-cell Population Expressing the Ectoenzymes CD38 and CD39 is Associated with Melanoma Patient Non-Response to Immunotherapy [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO030.