Obesity-Specific improvement of lung cancer outcomes and immunotherapy efficacy with metformin.

Abstract

Pre-clinical cancer studies ascribe promising anticancer properties to metformin. Yet, clinical findings vary, casting uncertainty on its therapeutic value for non-small cell lung cancer (NSCLC) patients. We hypothesized that metformin could benefit obese and overweight patients with NSCLC. We retrospectively analyzed two clinical cohorts and employed complementary mouse models to test our hypothesis. One cohort included NSCLC patients with overweight BMI (≥25, n = 511) and non-overweight BMI (<25, n = 232) who underwent lobectomy, evaluating metformin's impact on clinical outcomes. Another cohort examined metformin's effect on progression-free survival (PFS) after immune checkpoint inhibitors (ICI) in overweight (n = 284) vs non-overweight (n = 184) NSCLC patients. Metformin's effects on tumor progression, antitumor immunity, and ICI response in obese and normal-weight mice were assessed with lung cancer models. Metformin is associated with increased recurrence-free survival in overweight patients (HR = 0.47 [95%CI = 0.24-0.94], p = .035) after lobectomy. It also corrected accelerated tumor growth in diet-induced obese mouse models in a lymphocyte-specific manner while reversing several mechanisms of immune suppression potentiated by obesity. PD-1 blockade coupled with metformin was more effective at limiting tumor burden in obese mice and correlated with PFS only in overweight patients on immunotherapy (HR = 0.60, [95%CI = 0.39-0.93], p = .024). Metformin may improve lung cancer-specific clinical outcomes in obese and overweight lung cancer patients and enhance immunotherapy efficacy in this growing population as well. This work identifies obesity as a potential predictive biomarker of metformin's anticancer and immunotherapy-enhancing properties in lung cancer while shedding light on the underlying immunological phenomena.