Importance: Increased survival with immune checkpoint inhibitors has been reported for patients with obesity vs a normal body mass index (BMI). However, the association of obesity with the safety of immune checkpoint inhibitors warrants study.
Objective: To investigate associations between BMI and immune-related adverse events (irAEs) among patients with advanced cancers treated with nivolumab monotherapy and nivolumab plus ipilimumab combination therapy.
Design, setting, and participants: This study was a retrospective pooled analysis of 3772 patients from 14 multicenter CheckMate clinical trials across 8 tumor types. Patients with advanced cancers received nivolumab, 3 mg/kg (n = 2746); nivolumab, 3 mg/kg, plus ipilimumab, 1 mg/kg (n = 713); or nivolumab, 1 mg/kg, plus ipilimumab, 3 mg/kg (n = 313). Baseline BMI was categorized as normal weight or underweight (<25), overweight (25 to <30), or obese (≥30) according to World Health Organization criteria. The studies began patient enrollment between February 9, 2012, and May 21, 2015, and patients were followed up to database lock on May 1, 2019. Data analysis was conducted from May 1 to September 1, 2019.
Interventions: Nivolumab, 3 mg/kg; nivolumab, 3 mg/kg, plus ipilimumab, 1 mg/kg; and nivolumab, 1 mg/kg, plus ipilimumab, 3 mg/kg.
Main outcomes and measures: Odds ratios (ORs) and 95% CIs for incidence of any-grade and grade 3 or 4 irAEs were calculated for patients with obesity vs normal weight or underweight BMI in the overall cohort and in subgroups based on patient and tumor characteristics. Analyses for nivolumab plus ipilimumab cohorts were exploratory.
Results: A total of 3772 patients were included, 2600 were male (69%), and median age was 61 years (range, 18-90 years). For patients receiving monotherapy with nivolumab, 3 mg/kg (n = 2746), the incidence of any-grade irAEs was higher in patients with obesity (n = 543) vs those with normal weight or underweight BMI (n = 1266; OR, 1.71; 95% CI, 1.38-2.11). Incidence of grade 3 or 4 irAEs did not differ between patients with obesity and those with normal weight or underweight BMI (OR, 1.21; 95% CI, 0.92-1.61). Risk of any-grade and grade 3 or 4 irAEs appeared consistent with that in the overall population across all subgroups evaluated except for a higher likelihood of grade 3 or 4 irAEs among female patients with obesity vs normal weight or underweight BMI (OR, 1.73; 95% CI, 1.07-2.79). For patients receiving nivolumab plus ipilimumab, the incidence of irAEs appeared consistent across BMI categories.
Conclusions and relevance: Obesity appeared to be associated with an increased incidence of any-grade irAEs among patients treated with nivolumab monotherapy and with grade 3 or 4 irAEs among female patients only. These findings may inform the monitoring of patients at high risk of developing irAEs.