Background: 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.
Methods: 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.
Results: 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).
Conclusions: 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.
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