CTLA4 and obesity due to melanocortin 4 receptor deficiency: This phenomenon, often termed the 'obesity paradox,' refers to the observation that despite obesity being a known risk factor for various cancers and generally associated with poorer prognosis, obese patients may actually exhibit improved responses to immune checkpoint inhibitors (ICIs) such as anti-PD-1/PD-L1 and anti-CTLA-4 therapies.212, 213, 214 Several potential mechanisms have been proposed to explain this paradox.215