Effect of excess weight and immune-related adverse events on the efficacy of cancer immunotherapy with anti-PD-1 antibodies.

Immunotherapy is an effective treatment in advanced cancer, although predictors of response are limited. We studied whether excess weight influences the efficacy outcomes of immunotherapy. We have also evaluated the combined prognostic effect of excess weight and immune-related adverse events (irAEs). Efficacy of anti-PD-1 treatment was evaluated with both objective radiological response (ORR) rate and progression-free survival (PFS), and toxicity with irAEs. We studied the association between excess weight and ORR, PFS or irAEs. 132 patients diagnosed with advanced cancer were included. Median body mass index (BMI) was 24.9 kg/m2. 64 patients had normal weight (BMI<25 kg/m2), and 64 patients had excess weight (BMI≥25 kg/m2). Four patients had underweight and were excluded from further analysis. ORR was achieved in 50 patients (38.0%), median PFS was 6 months. 44 patients developed irAEs (33.3%). ORR was higher in excess weight patients than in patients with normal weight (51.6% vs 25.0%; OR 3.45, p = .0009). PFS was improved in patients with excess weight (7.25 months vs 4 months, HR 1.72, p = .01). The incidence of IrAEs was not different in patients with excess weight (54.5% vs 43.2%, p = .21). When high BMI and irAEs were combined, we observed a marked prognostic trend in ORR rate (87.5% vs 6.2%; OR 161.0, p < .00001), and in PFS (14 months vs 3 months; HR 5.89, p < .0001). Excess weight patients with advanced cancer that receive single-agent anti-PD-1 antibody therapy exhibit a significantly improved clinical outcome compared with normal BMI patients. This association was especially marked when BMI and irAEs were considered combined.