Preclinical studies have reported that obesity hampers the response to anti–programmed cell death 1 (PD-1) therapy.23,24 For instance, a preclinical study involving mice with intrakidney tumors receiving anti-PD-1–based immunotherapy reported a lower frequency of treatment responders in obese mice compared with lean mice.23 This study suggested that host obesity, rather than factors such as a high-fat diet, was responsible for the reduced efficacy of immunotherapy. This evidence concerns the gene PDCD1 and obesity due to melanocortin 4 receptor deficiency.