LAUSR

Ceritinib is a potent selective ALK inhibitor with a manageable safety profile. In anecdotal reports, ceritinib was associated with organizing pneumonia (OP), which could be confused with disease progression. We aimed to delineate the characteristics of OP that occurs during treatment with ceritinib, and evaluate its clinical implications. We retrospectively analyzed 44 lung cancer patients whose tumors harbored ALK or ROS1 fusions and who had received ceritinib. OP diagnosis was based on radiographic and clinical features. Four OP cases were pathologically confirmed. Among 44 patients, 22 OP events occurred in 16 (36.4%) patients. The median time to the first event was 17.2 weeks (range 6.7–68.7 weeks). All events were grade 1 or 2. Radiographic features were categorized into four patterns: nodular (54.6%), consolidation (27.3%), parenchymal band (4.5%), and ground-glass opacity (GGO) (13.6%). OP improved in 20 events with drug interruption or corticosteroids. The median duration of OP was 11.3 weeks (range 2–24 weeks). Tumor response rate was 75% in OP-positive and 42.9% in OP-negative groups. The median progression-free survival was 16.7 months [95% confidence interval (CI) 10.1–not applicable (NA)] in OP-positive and 5.4 months (95% CI 3.6–8.4) in OP-negative patients (P = 0.004). The median overall survival was 46.2 months (95% CI 38.1–NA) in OP-positive and 10.5 months (95% CI 6.2–18.9) in OP-negative patients (P < 0.001). OP occurs frequently during ceritinib treatment and must be distinguished from disease progression. OP could be reversible without fatal complications and its occurrence is associated with better survival outcomes.