FASN and obesity due to melanocortin 4 receptor deficiency: Second, we investigated the therapeutic benefits of fatty acid metabolism inhibition in myeloma cells using etomoxir (a specific inhibitor of CPT I, which has been used in clinical trials in patients with chronic heart failure) [11], [12] and orlistat (a Food and Drug Administration (FDA)-approved anti-obesity drug that specifically inhibits FASN activity) [13], [14].