What is the most frequently reported adverse event with PD-1 and PD-L1 inhibitors?
Fatigue is the most commonly reported AE with these agents, and the pathogenesis is poorly understood. Individual drug studies report fatigue in 16% to 37% of patients on PD-1 inhibitors and 12% to 24% of patients on PD-L1 inhibitors. Of the patients who report fatigue with these agents, only a minority will have hypothyroidism as a cause. Regardless, patients with even subtle changes in their energy level should have adrenal and thyroid laboratory values assessed to evaluate for potential endocrinopathies.