Pneumonitis associated with pembrolizumab plus chemotherapy for non-squamous non-small cell lung cancer

Studies elucidating detailed characteristics of pneumonitis in association with chemo-immunotherapy are limited. We aimed to investigate the characteristics of images, prognostic factors, and clinical course of combination therapy associated with pneumonitis. A multicenter, retrospective cohort study of patients with non-squamous non-small cell lung cancer who received a combination of platinum, pemetrexed, and pembrolizumab was conducted. Patients with confirmed pneumonitis established by an independent multidisciplinary team were enrolled. For 53 patients with pneumonitis, radiographic features at diagnosis predominantly comprised an organizing pneumonia pattern (62%, 33/53). Twelve (23%) patients experienced a worsening respiratory status during pneumonitis management, which was associated with a high mortality rate (58%, 7/12) during treatment. Severe grade at pneumonitis diagnosis (p < 0.001), diffuse alveolar damage (DAD) pattern (p = 0.002), and disease extent ≥ 25% in the lungs (p = 0.009) were significantly associated with worsening respiratory status. Furthermore, post-diagnosis survival was significantly worse in severe pneumonitis (p = 0.02) than in mild and in patients with the DAD pattern than in those without (p < 0.0001). We showed detailed clinical course of patients with pneumonitis and reported several important influencing factors. Given the small number of trials on pneumonitis, our findings provide valuable information to guide the development of appropriate management guidelines and improve pneumonitis treatment.