Abstract LB-151: Prophylactic TNFα blockade unplugs toxicity and efficacy in immunotherapy anti-PD-1 + anti-CTLA-4 combinations

The combination of anti-CTLA-4 and anti-PD-1 checkpoint inhibitors ipilimumab and nivolumab (DIT) has improved survival of patients with metastatic melanoma and renal cell carcinoma in exchange for frequent immune-mediated serious side effects (mainly gastrointestinal), leading to treatment cessation in about one third of the patients and the need to reduce doses of these immunotherapy agents when used in combination. Tumor necrosis factor-α (TNF-α) is an important actionable mediator in inflammatory bowel disease (both ulcerative colitis and Crohn9s disease) and its blockade with monoclonal antibodies has been recommended to treat steroid-resistant colitis following checkpoint inhibitors. We have studied whether prophylactic TNFα blockade is able to reduce immune toxicity associated with DIT without altering antitumor activity. Experiments were performed in C57BL/6 mice harboring subcutaneous tumors derived from the MC38 and B16OVA cell lines. Acute immune-mediated colitis was induced by exposure to 3% dextran sulfate sodium (DSS) in drinking water for 3 days. For TNFα blockade etanercept (hTNFR2-IgG chimera) or a mouse anti-TNF-α monoclonal antibody were used. Anti-tumor efficacy was tested following individual tumor sizes upon combined treatment with anti-mPD-1 + anti-mCTLA4 mAbs. Severity of DSS colitis was assessed and scored by daily weight, ultrasound evaluation of intestinal wall thickness and histological assessment on day 7. We observed that the antitumoral efficacy of PD-1+CTLA-4 blockade against MC38 of B16OVA established tumors was not reduced with the prophylactic association of TNF-α blockade. Intriguingly, an improvement of antitumor activity was observed in those mice in which DSS colitis was induced. Importantly, in mice suffering DSS-induced colitis that were co-treated with DIT and TNF-α blockade, digestive toxicity ameliorates as shown by body weight, ultrasound examination and histology. Therefore, TNF-α blockade can be prophylactically associated with anti-PD1 + anti-CTLA-4 mAb combination regimens to prevent toxicity without hindrance of anti-tumor efficacy. These results in mouse models warrant a clinical trial testing profilactic etanercept to improve the safety profile of the nivolumab + ipilimumab combination widening its therapeutic window. Citation Format: ELISABETH PEREZ-RUIZ, LUNA MINUTE, MARIA CARMEN OCHOA, ARANTXA AZPILICUETA, SARAY GARASA, M E RODRIGUEZ-RUIZ, VIRGINIA BELSUE, CARMEN MOLINA, PEDRO BERRAONDO, IGNACIO MELERO. Prophylactic TNFα blockade unplugs toxicity and efficacy in immunotherapy anti-PD-1 + anti-CTLA-4 combinations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-151.