CXCL8 and obesity due to melanocortin 4 receptor deficiency: The blunting effect of obesity on GW9662 and αPD-L1 could be due to obesity-triggered elevation of adipocyte-derived factors such as PD-L1, leptin, and IL-8, all of which are known to antagonize host antitumor immunity and the therapeutic efficacy of checkpoint blockade immunotherapies 11, 28-30.