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BACKGROUND: Preclinical 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. METHODS: We retrospectively analyzed 2 clinical cohorts and employed complementary mouse models to test our hypothesis. One cohort included NSCLC patients with overweight body mass index (≥25 kg/m2, n = 511) and nonoverweight body mass index (<25 kg/m2, n = 232) who underwent lobectomy, evaluating metformin's impact on clinical outcomes. Another cohort examined metformin's effect on progression-free survival after immune checkpoint inhibitors in overweight (n = 284) vs nonoverweight (n = 184) NSCLC patients. Metformin's effects on tumor progression, antitumor immunity, and immune checkpoint inhibitor response in obese and normal-weight mice were assessed with lung cancer models. RESULTS: Metformin is associated with increased recurrence-free survival in overweight patients (hazard ratio HR = 0.47, 95% confidence interval CI = 0.24 to 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. Programmed cell death 1 blockade coupled with metformin was more effective at limiting tumor burden in obese mice and correlated with progression-free survival only in overweight patients on immunotherapy (HR = 0.60, 95% CI = 0.39 to 0.93; P = .024). CONCLUSIONS: Metformin may improve lung cancer-specific clinical outcomes in obese and overweight lung cancer patients and enhance immunotherapy efficacy in this growing population. 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.
Smith et al. (Tue,) studied this question.