Overcoming acquired resistance to PD-1 inhibitor with the addition of metformin in small cell lung cancer (SCLC)

AbstractMetformin has been widely used as the treatment of type II diabetes mellitus for its anti-hyperglycemic effect. In recent years, it has also been extensively studied for its anti-cancer effect as it diminishes immune exhaustion of CD8  + tumor-infiltrating lymphocytes (TILs). It decreases apoptosis of CD8 + TILs, thereby enhancing T cell-mediated immune response to tumor cells. Here, we present a unique case of a patient with small cell lung cancer (SCLC) who exhibited an overall partial response as per Response Evaluatio n Criteria in Solid Tumors, version 1.1 (RECIST 1.1) since starting metformin in combination with nivolumab therapy. Our patient had been treated with nivolumab monotherapy for 2 years until she had progression of disease. After she was started on metformin along with nivolumab therapy, she has sho wn a significant durable response for over 6 months. Many patients develop resistance to immunotherapy such as antibodies against cytotoxic T lymphocyte-associated protein 4 (CTLA-4), programmed cell death 1 (PD-1), and programmed cell death ligand 1 (PD-L1). Tumor hypoxia is one of the resistance factors. Signals activated by hypoxic environments in tumors are associated with decreased sensitivity to the PD-1 blockade. Metformin inhibits oxygen consumption in tumor cells in vitro and in vivo, reducing intratumoral hypoxia. These data suggest that metformin can improve susceptibility to anti- PD-1 treatment. To the best of our knowledge, our case...
Source: Cancer Immunology, Immunotherapy - Category: Cancer & Oncology Source Type: research