PDCD1 and pneumonitis: Pneumonitis is an uncommon but potentially fatal adverse effect of anti-PD-1 therapy.[22] Pneumonitis related to anti-PD-1 therapy occurs with an incidence of about 5%, but the incidence of grades 3 to 4 pneumonitis is only around 1% to 2%.[8,9,11,13,22,23] The main clinical manifestations of immunotherapy-related pneumonitis are cough, chest pain, and dyspnea, although a few patients can be asymptomatic and present only with pulmonary imaging changes such as ground-glass opacities, mesh-like shadows, and non-specific interstitial pneumonia-like changes.