Abstract 15049: Combinatorial Immune Checkpoint Blockade Increases Myocardial Secretion of H-FABP, NT-Pro-BNP, NLRP-3 Inflammasome, Interleukin-1β and Interleukin-6: Biochemical Implications in Cardio-Immuno-Oncology

Abstract

Background: Immune checkpoint blockade alone or in combination with chemotherapy or radiotherapy or other immune checkpoint blocking agents have become an integral part of oncology in recent years. Monoclonal antibodies against CTLA-4 or PD-1 or PDL-1 are the most studied ICIs in randomized clinical trials, however, more recently, an anti-LAG3 (Lymphocyte activation gene-3) human monoclonal antibody, Relatlimab, has been approved by FDA for combinatorial treatment with Nivolumab for metastatic melanoma. Moreover, anti PD-L1blocking agent Atezolizumab is actually under study in association with Ipilimumab as innovative thearpy for metastatic lung cancer. Cases of cardiotoxicity such as myocarditis, vasculitis and endothelitis are rarely observed in these patients on monotherapy, however new combination therapies and the use of new targets in immunotherapy could expose patients to more adverse cardiovascular events. Methods: human cardiomyocytes co-cultured with human peripheral blood lymphocytes (hPBMCs) were exposed to monotherapy and combinatorial ICIs (PD-L1 and CTLA-4 or PD-1 and LAG-3 blocking agents, at 100 nM) for 48 h. After treatments, cardiac cell lysis and secretion of biomarkers of cardiotoxicity (H-FABP, NT-Pro-BNP), NLRP3-inflammasome and Interleukin 1 and 6 were determined through colorimetric and enzymatic assays. Results: Both combinations of immune checkpoint inhibitors exert more potent cardiotoxic side effects compared to monotherapies against human cardiac cells co-cultured with human lymphocytes. LDH release from cardiac cells was 43% higher in PD-L1/CTLA-4 blocking agents, and 35.7% higher in PD-1/LAG-3 blocking agents compared to monotherapies. Biomarkers of cardiotoxicity, such as NT-Pro-BNP and H-FABP, were also strongly increased in combination therapy with respect to monotherapies. NLRP3 inflammasome, IL-6 and IL-1β levels were also increased by PDL-1/CTLA-4 and PD-1/LAG-3 combined blocking agents compared to untreated cells and monotherapies. Conclusions: Data of the present study, although in vitro, indicate that combinatorial immune checkpoint blockade, induce a pro- inflammatory phenotype.