LAUSR

Abstract Background The use of immune checkpoint inhibitors (ICI) has revealed a new panel of tumor response and adverse events. Immune-related sarcoidosis-like reactions is frequently misdiagnosed as progressive or recurrent disease. This study aims to decipher the diagnosis hallmark of immune-related sarcoidosis-like reactions as well as its association with patients’ outcome. Methods From August 2014 and December 2018, in a centralized single center review, we retrospectively included all patients with histologically proven immune-related sarcoidosis-like reaction during a treatment with ICI in monotherapy or combination. 54 variables were retrospectively recorded: clinical (n = 17), biological (n = 11) and radiological (n = 26), as well as the objective response to treatment using the best overall response according to iRECIST. Results Out of 3,200 patients treated with ICI, a total of 18 histologically proven sarcoidosis were diagnosed. The majority were female patients (n = 11/18) treated for melanoma (n = 14/18) or clear renal cell carcinoma (n = 3/18). The median [range] time to diagnosis of a sarcoidosis-like reaction was 30 [5-126] weeks after ICI treatment initiation. On CT-scans, the most common radiological findings were: absence of radiographical progression of the primary tumor per RECIST1.1 (100%), bilateral symmetrical mediastinal lymphadenopathy (100%), symmetrical hilar lymphadenopathy (84%), and micronodules with lymphatic distribution (15%). On PET-CT, an extrathoracic glucose uptake was observed in 65% of patients. The sites involved were pleural involvement, abdominal lymph nodes, liver, and spleen. Patients with immune-related sarcoidosis-like reactions were objective responders according to iRECIST in 84% (n = 15/18) of patients, while only 15% had stable disease. Conclusions Immune-related sarcoidosis is characterized by the appearance of new mediastinal and/or pulmonary lesions, usually at 30 weeks after initiation of treatment, with stability of baseline target lesions. PET/CT demonstrated extrathoracic uptake in 65% of patients. This should not be misinterpreted as disease progressive since 84% of patients will show an objective response to ICI. Legal entity responsible for the study Ammari Sami. Funding Has not received any funding. Disclosure S. Champiat: Advisory / Consultancy: Astrazenaca; Advisory / Consultancy: BMS; Advisory / Consultancy: Janssen; Advisory / Consultancy: MSD; Advisory / Consultancy: Roche. J. Michot: Advisory / Consultancy: BMS. All other authors have declared no conflicts of interest.