A Multidisciplinary Approach to Improve the Management of Immune-Checkpoint Inhibitor-Related Pneumonitis.

Purpose: Treatment with immune-checkpoint inhibitors (ICIs) can be associated with a wide spectrum of immune-related adverse events (irAEs). Among irAEs, immune-mediated pneumonitis (im-PN) is a rare but potentially life-threatening side effect. TPrompt multidisciplinary diagnosis and effective management of im-PN may be essential to avoid severe complications and allowing resumation of therapy.

Patients and methods: We collected a case series of skin (melanoma, cutaneous squamous cell carcinoma-CSCC), lung, and mesothelioma cancer patients (pts), treated with ICI at the Center for Immuno-Oncology University Hospital of Siena, Italy, and diagnosed with im-PN. Clinical and radiologic data were thoroughly collected, as well as bronchoalveolar lavage (BAL) samples; im-PN was graded using CTCAE v. 5.0. Radiological patterns were reported according to the Fleischner Society classification.

Results: From January 2014 to February 2023, 1004 patients with melanoma (522), CSCC (42), lung (342) or mesothelioma (98) were treated with ICI (619 monotherapy; 385 combination). Among treated patients, 24 (2%) developed an im-PN and 58% were symptomatic. Im-PN were classified as grades G1 (10) and G2 (14). Prompt steroid treatment led to complete resolution of im-PN in 21 patients, with a median time to resolution of 14 weeks (range: 0.4-51). Twelve patients resumed ICI therapy once fully-recovered and 2 experienced a recurrence that completely resolved with steroids after resumption of treatment. Three radiologic patterns were identified: organizational pneumonia-like (67%), pulmonary eosinophilia (29%), and hypersensitivity pneumonitis (4%). Furthermore, BAL analysis performed in 8 (33%) patients showed an inflammatory lymphocytic infiltrate, predominantly consisting of foam cell-like macrophage infiltrates in 6 cases. Notably, transmission electron microscopy evaluation performed in 2 patients revealed a scenario suggestive of a drug-mediated toxicity.

Conclusion: Im-PN is a rare but challenging side effect of ICI therapy, with variable time of onset and with heterogeneous clinical and radiological presentations. A multidisciplinary assessment is mandatory to optimize the clinical management of im-PN.