PDCD1 and obesity due to melanocortin 4 receptor deficiency: In addition, intriguing results from Donnelly et al. illustrate that even within the same cohort of melanoma patients, obesity-associated outcomes diverge for anti-PD-1 monotherapy versus anti-PD-1 + anti-CTLA-4 combination therapy (37); this finding suggests that underlying therapy-induced immune responses may be differentially impacted by host obesity.