Background The impact of overweight/obesity in cancer patients treated with immune checkpoint inhibitors (ICIs) is controversial. To further contribute to this debate, we performed a systematic review and meta-analysis of published articles evaluating the effects of overweight/obesity on survival and immune-related adverse events (irAEs).

Materials and Methods In analogy to Cochrane recommendations, systematic literature searches included all published articles in PubMed until February 2021 with key terms ‘obesity’ and ‘overweight’ and ICI treatment irrespective of cancer entity and ICI used. Further selection criteria for meta-analysis included WHO cut-offs for overweight/obesity. For the random effects meta-analysis, we used Hazard Ratios (HR) for overall and progression-free survival (OS, PFS) and Odds Ratios (OR) for occurrence of irAEs with corresponding 95% confidence intervals (95%CI), respectively.

Results A total of 30 studies (12,895 patients, 38% female) selected for meta-analysis revealed a superior survival of overweight/obese patients (PFS: HR 0.9, 95%CI 0.77-1.04, p = 0.11; OS: 0.74, 95%CI 0.63-0.92, p = 0.0005) compared to normal weight patients. In subgroup analyses based on sex, overweight/obese male patients showed increased survival (PFS: HR 0.79, 95%CI 0.63-1.00, p = 0.05; OS: 0.71, 95%CI 0.58-0.86, p = 0.0005), whereas overweight/obese female patients had similar survival probabilities compared to their normal weight counterparts (PFS: HR 1.01, 95%CI 0.69-1.47, p = 0.96; OS: HR 0.73, 95%CI 0.48-1.10, p = 0.13). Underweight patients showed inferior survival (PFS: HR 1.48, 95%CI 1.07-2.04, p = 0.02; OS: HR 1.86, 95%CI 1.13-3.04, p = 0.01). In addition, overweight/obese patients had a higher risk of developing irAEs with grade ≥ 3 (OR 1.91, 95%CI 1.18-3.10, p = 0.008).

Conclusions Our meta-analysis revealed that overweight/obesity is a beneficial factor for PFS and OS in a mixed cohort of cancer patients undergoing ICI treatment accompanied by an increased risk of severe irAEs. The differences between overweight/obese males and overweight/obese females might point to sex specific adipose distribution patterns and interactions of sex steroids on a molecular level. A significant number of studies included underweight patients into normal weight control groups which led to a compromised interpretation of the data and should be addressed in future studies.

Disclosure Information P. Trinkner: None. S. Günther: None. M. von Bergwelt: None. D. Cordas dos Santos: None. S. Theurich: None.