Fasting mimicking diet reduces anti-OX40/anti PD-L1 and anti-PD-1/anti-CTLA-4 cardiovascular side effects in preclinical melanoma models.

12029 Background: Several strategies based on immune checkpoint inhibitors (ICIs) have been developed or are under investigation as cancer therapeutics with the potential to increase survival. However, ICIs-induced side effects ranging from autoimmune endocrine disorders to mucositis and to a rare but clinically significant cardiotoxicity with high rate of mortality represent important limitations. Cardiovascular complications in ICIs-treated patients includes myocarditis, vasculitis, arrhythmia, fibrosis and heart failure. Moreover, both the limited efficacy in a large portion of patients and the acquisition of resistance represent additional limitations for ICIs, underlining the need for new immunotherapy strategies. Fasting mimicking diets (FMDs) applied for several days periodically are emerging as highly promising enhancers of a wide variety of cancer therapies including immunotherapy. Here, a preclinical study in melanoma-bearing mice treated with two combinatorial ICIs therapies (anti-OX-40/PDL-1 or antiCTLA-4/anti-PD-1) during a standard or FMD was performed. Methods: Melanoma or lung cancer-bearing mice ( C57BL/6J female mice, 6–8 weeks old) were treated with two combinatorial ICIs therapies (anti-OX-40/PDL-1 or antiCTLA-4/anti-PD-1) during a standard diet or FMD for 21 days. Tumors were measured every 3–4 days using a digital caliper. Mice were monitored for tumor growth and survival. Mice were killed when tumor volume reached 1.5 cm3. Flow cytometry analysis of tumor-infiltrating lymphocytes and apoptosis, collagen quantification in myocardial tissues, quantification of CD3+ and CD8+ cells in myocardial tissues, of plasma and myocardial cytokines, and several pro-inflammatory biomarkers were performed through selective ELISA methods and western blotting analysis. Results: FMD cycles in combination with anti-OX40/anti-PD-L1 also show a trend for increased effects against a lung cancer model. As importantly, the cardiac fibrosis, necrosis and hypertrophy caused by immune checkpoint inhibitors are prevented/reversed by FMD treatment in both cancer models whereas immune infiltration of CD3 + and CD8 + cells in myocardial tissues and systemic and myocardial markers of oxidative stress and inflammation are reduced. These results indicate that FMD cycles in combination with immunotherapy can delay cancer growth while reducing side effects including cardiotoxicity. Conclusions: This study sets the stage for clinical trials aimed at assessing the ability of FMD to increase the efficacy of immunotherapy while reducing its side effects. These results also indicate that the anti-inflammatory and protective effects of FMD cycles in combination with ICI could affect other organs and systems.