Effect of body mass index on immune checkpoint inhibitor efficacy in patients with advanced cancer

Background: The need for predictive factors regarding the response to immune checkpoint inhibitors (ICIs) is increasing. Recent research indicates that an enhanced response to ICIs is associated with a higher body mass index (BMI). This study aims to evaluate the relationship between response to ICIs and BMI in solid tumors. Methods: We retrospectively analyzed patients with advanced cancer treated with ICIs at one academic center. We compared the treatment responses of patients classified as underweight/normal weight (BMI <25) and overweight/obese (BMI ⩾ 25) according to their BMI at the initiation of ICI treatment. After excluding underweight patients, we also compared the progression-free survival (PFS) and overall survival (OS) of normal-weight, overweight, and obese patients. Results: Overall, 113 patients were evaluated. Forty-seven (41.6%) patients had BMI <25 and 66 (58.4%) patients had a BMI ⩾ 25. In underweight/normal patients, median PFS was 7.7 months (95% CI: 4.7-10.6) while it was 8.0 months (95% CI: 4.1–11.9) in overweight/obese patients (HR 1.16, 95% CI: (0.76-1.75), p=0.477). In underweight/normal patients, the median OS was 21.7 months (95% CI: 11.6-31.7) compared to 18.7 months (95% CI: 12.7-24.6) in overweight/obese patients (HR 1.06, 95% CI: (0.69-1.64), p=0.774). The objective response rate (ORR) was 38.3% in underweight/normal patients and 34.8% in overweight/obese patients (p = 0.707). After excluding underweight patients, there were also no significant differences in PFS (p = 0.914), OS (p = 0.642), and ORR (p = 0.909) between patients of normal weight, overweight, and obesity. Conclusion: Our research found no correlation between BMI and response to ICIs. Additional prospective studies are necessary to assess the effect of BMI on the response to ICIs.