BACKGROUND: Immunotherapy (IT) has been established as treatment in cancer. However, 5% of patients can develop pneumonitis. Some of them can present pneumonitis relapses when corticoids are reduced or stopped. The aim of this study is to identify possible risk factors of immune-related pneumonitis relapses (IRPR).

MATERIAL AND METHODS: Retrospective study of patients with IRPR between 2020-2022 was carried out. Anthropometric, clinical, cancer-related, lung function, blood analysis and radiological data were registered. Grade immune-related pneumonitis using ESMO criteria.

RESULTS: Fifty-five patients were included: 40 (72%) with lung cancer (LC), 6 (11%) genitourinary cancer (GUC), 3 (5%) melanoma, 2 (4%) hepatocarcinoma, (HCC) 2 (4%) head-neck cancer (HNC), 1 (2%) breast and 1 (2%) ovary cancer (OC). 21 (38%) patients developed IRPR distributed as follows: 16 (75%) LC, 2 (10%) GUC, 1 (5%) HCC, 1 (5%) OC and 1 (5%)HNC.

Treatments received were: nivolumab (22%), pembrolizumab (35%), durvalumab (29%), atezolizumab (11%) or tisrelizumab (4%). 30 (55%) patients with LC received previous thorax radiotherapy (RT). No differences were found between treatments or RT and IRPR. 7 (13%) patients developed extra-lung IT-related toxicity.

IRPR chest computed tomography (CT) patterns were: 2 (10%) ground-glass opacities (GGO), 9 (43%) organized-pneumonia (OP), 9 (43%) GGO and reticulation and one (5%) sarcoid-like. Higher prevalence of GGO and reticulation or OP was observed in IRPR patients (p=0.003). Development of IRPR wasn?t associated with anthropometric, lung function parameters, blood analysis or pneumonitis grade.

CONCLUSION: There?s a high prevalence of IRPR. GGO and reticulation or OP on chest-CT may predispose its appereance.