LEP and obesity due to melanocortin 4 receptor deficiency: Our search term for the PubMed database was as follows: leptin AND obesity, (leptin OR obesity) AND cancer, (leptin OR obesity) AND treatment AND cancer, (leptin OR obesity) AND immunotherapy, (leptin OR obesity) AND immune system, obesity AND immune system AND immunotherapy, (leptin OR obesity) AND inflammation, immune system AND inflammation, cancer AND inflammation, (immunotherapy OR treatment) AND inflammation AND cancer.