Abstract 2326: LTX-315, an oncolytic peptide, increases anticancer immunity mediated by CTLA4 blockade in an interleukin-2 receptor beta-chain-dependent manner

Abstract Intratumoral immunotherapies aim at reducing local immunosuppression as well as reinstating and enhancing systemic anticancer T cell functions without inducing side effects. LTX-315 is a first-in-class oncolytic peptide -based local immunotherapy that meets these criteria by inducing a type of malignant cell death that elicits anticancer immune responses. Here, we show that LTX-315 rapidly reprograms the tumour microenvironment by decreasing the local abundance of immunosuppressive Tregs and myeloid derived-suppressor cells and by increasing the frequency of polyfunctional TH1/TC1 cells with a concomitant raise in their expression of CTLA4 and a drop in PD-1 expression. Logically, in tumours that were resistant to intratumoural or systemic CTLA4 blockade, subsequent local inoculation of LTX-315 cured the animals or caused tumour regressions with abscopal effects(meaning that even malignant lesions that were established in the opposite flank and were not treated by LTX-315 responded to the therapy). This synergistic interaction between CTLA4 blockade and LTX-315 was reduced upon blockade of the β-chain of the interleukin-2 receptor (CD122) which is required for signalling in response to IL-2 and IL-15. This preclinical study provides a strong rationale for administering the oncolytic peptide LTX-315 to patients who are receiving treatment with the CTLA4 blocking antibody ipilimumab. Citation Format: Takahiro Yamazaki, Marie Vetizou, Camila Flores, Aurelien Marabelle, Baldur Sveinbjørnsson, Øystein Rekdal, Guido Kroemer, Laurence Zitvogel. LTX-315, an oncolytic peptide, increases anticancer immunity mediated by CTLA4 blockade in an interleukin-2 receptor beta-chain-dependent manner. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2326.