Small cell lung cancer transformation during immunotherapy with nivolumab: A case report

We report a rare case of transformation of non-small cell lung cancer (NSCLC) to small cell lung cancer (SCLC), without epidermal growth factor receptor (EGFR) gene mutation, during immunotherapy treatment with nivolumab. A 75-year-old man was referred to our hospital following the observation of a 64 mm mass in a chest computed tomography (CT) scan. A transbronchial biopsy of the mass identified the pathological presence of poorly differentiated NSCLC, with no histological signs of SCLC. No mutations were identified in the EGFR gene. A clinical diagnosis of NSCLC (cT3N3M1a, stage IV) was made following a positron emission tomography (PET)-CT scan and enhanced brain magnetic resonance imaging. Docetaxel and bevacizumab were selected as the first-line chemotherapy regimen; however, after two cycles, the patient developed a gastrointestinal perforation, and discontinuation of cytotoxic chemotherapy was recommended. Owing to gradual disease progression, immunotherapy with nivolumab was selected as the second-line regimen. During the immunotherapy, the tumor continued to progress and some subcutaneous tumors emerged. Biopsy of a subcutaneous tumor revealed SCLC, with positive immunostaining for cluster of differentiation 56, synaptophysin, and thyroid transcription factor-1. Serum tumor markers of SCLC were also elevated. Based on these results, we concluded that in this case NSCLC had transformed to SCLC during immunotherapy with nivolumab. (C) 2017 The Authors. Published by Elsevier Ltd.