In animal and in vitro studies, the obesity-related high levels of adipokines, such as leptin and resistin, impaired the therapeutic efficacy of dacarbazine (DTIC) towards melanoma regression and induced a drug-resistant phenotype by upregulating fatty acid synthase (FASN), caveolin (Cav)-1, and P-glycoprotein (P-gp) [21,22]. Here, RETN is linked to obesity due to melanocortin 4 receptor deficiency.