Pneumonitis From Anti-PD-1/ PD-L1 Therapy.

Pneumonitis is defined as a focal or diffuse inflammation of the lung parenchyma, and is a known, potentially fatal toxicity of anti-programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) immune checkpoint inhibitors. Herein we discuss two patients who developed pneumonitis secondary to anti-PD-1/PD-L1 immune checkpoint inhibitor therapy and illustrate a stepwise approach to the diagnostic evaluation and management of anti-PD-1/PD-L1-related pneumonitis. In the majority of patients who develop this toxicity, pneumonitis appears to clinically resolve with corticosteroid therapy alone; however, a subset of patients require additional immunosuppressive medications. Patients who clinically improve with steroid treatment must be monitored closely in the outpatient setting. If pneumonitis management results in complete clinical and radiologic resolution, patients may be able to restart their immune checkpoint inhibitor therapy. It is currently unclear which population of patients is more susceptible to developing higher-grade or steroid-refractory pneumonitis.