Chronic pleuritis and recurrent pleural effusion after atezolizumab for small cell lung cancer

Abstract

Background: As use of immune checkpoint inhibitors consistently grows, so does knowledge of immune-related adverse events. Pleural complications from PD-L1 inhibitors such as atezolizumab have never been reported. We de-scribe the first reported case of biopsy-proven pleuritis manifesting as recurrent pleural effusion in a patient treated with atezolizumab. A 66-year-old woman with history of extensive-stage small cell lung cancer presented with a new pleural effu-sion. She was previously treated with carboplatin, etoposide, and atezolizumab followed by atezolizumab main-tenance, but this later was stopped due to pneumonitis. She had been on no systemic therapy for 6 months prior; radiation to the chest was completed 1 year earlier. Thoracentesis revealed an exudate with eosinophil-ia but no malignancy. She underwent medical thoracoscopy, which showed normal pleura with no evidence of radiation changes. Random pleural biopsies revealed only chronic pleuritis. Given normal-appearing pleu-ra, radiation pleuritis was ruled out. It was felt that the chemotherapy had occurred too long ago to be a present cause of her pleuritis. As such, after extensive workup, the eosinophilic pleural effusion was felt to be due to pleuritis from atezolizumab. The effusion has ultimately recurred 5 times over 1 year, and cytology remains negative for malignancy. Patients with prior cancer presenting with a new pleural effusion should undergo an extensive workup to evaluate for recurrence. When other causes have been ruled out, ongoing immune-related effects of immunother-apy should be considered. Pleural complications from PD-L1 inhibitors have not been reported; we present a possible case of chronic pleuritis and recurrent effusion due to atezolizumab.