Purpose: Investigate the clinical characteristics, radiographic patterns, and treatment course of PD-1 inhibitor–related pneumonitis in advanced cancer patients.

Experimental Design: Among patients with advanced melanoma, lung cancer, or lymphoma treated in trials of nivolumab, we identified those who developed pneumonitis. Chest CT scans were reviewed to assess extent, distribution, and radiographic patterns of pneumonitis.

Results: Among 170 patients treated in 10 different trials of nivolumab, 20 patients (10 melanoma, 6 lymphoma, and 4 lung cancer) developed pneumonitis. Five patients received nivolumab monotherapy, and 15 received combination therapy. The median time from therapy initiation to pneumonitis was 2.6 months. Radiographic pattern was cryptogenic organizing pneumonia (COP) in 13, nonspecific interstitial pneumonia (NSIP) in 3, hypersensitivity pneumonitis (HP) in 2, and acute interstitial pneumonia (AIP)/acute respiratory distress syndrome (ARDS) in 2 patients. The AIP/ARDS pattern had the highest grade, followed by COP, whereas NSIP and HP had lower grade (median grade: 3, 2, 1, 1, respectively; P = 0.006). The COP pattern was most common in all tumors and treatment regimens. Most patients (17/20; 85%) received corticosteroids, and 3 (15%) also required infliximab. Seven patients restarted nivolumab therapy; 2 of them developed recurrent pneumonitis and were successfully retreated with corticosteroids. One of the patients experienced a pneumonitis flare after completion of corticosteroid taper without nivolumab retreatment.

Conclusions: PD-1 inhibitor–related pneumonitis showed a spectrum of radiographic patterns, reflecting pneumonitis grades. COP was the most common pattern across tumor types and therapeutic regimens. Most patients were successfully treated with corticosteroids. Recurrent pneumonitis and pneumonitis flare were noted in a few patients. Clin Cancer Res; 22(24); 6051–60. ©2016 AACR.

See related commentary by Castanon, p. 5956