Pneumonitis associated with anti–programmed death-1 (PD-1)/programmed death ligand 1 (PD-L1) monoclonal antibodies is more common when given in combination with anti-cytotoxic T-cell lymphocyte-4 (CTLA-4) monoclonal antibodies, according to a study published in the Journal of Clinical Oncology.1

Though uncommon, PD-1/PD-L1 inhibitor-related pneumonitis can be severe and even life-threatening for patients treated for advanced solid malignancies, including melanoma and non-small cell lung cancer. The clinical, radiologic, and pathologic features of this immune-mediated adverse event are, however, unclear.

Investigators analyzed data from 915 patients treated with anti-PD-1/PD-L1 monoclonal antibodies as monotherapy or in combination with a CTLA-4 inhibitor.

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Five percent of patients developed immune-mediated pneumonitis. Time to onset of pneumonitis ranged from 9 days to 19.2 months.

The incidence of pneumonitis was 10% with combination immunotherapy, versus 3% with monotherapy (P < .01), though the incidence was similar between patients with melanoma and those with non-small cell lung cancer.

Seventy-two percent of pneumonitis cases were grade 1 to 2, and 86% improved or resolved with treatment interruption and/or immunosuppression with a corticosteroid, suggesting that most pneumonitis events are low grade and improve or resolve with appropriate treatment.

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Five patients with pneumonitis died, of which 3 were due to immunosuppression-associated infection. One death was attributed to pneumonitis.          


  1. Naidoo J, Wang X, Woo KM, et al. Pneumonitis in patients treated with anti–programmed death-1/programmed death ligand 1 therapy. J Clin Oncol. 2016 Sep 19. doi: 10.1200/JCO.2016.68.2005 [Epub ahead of print]