title: Small cell lung cancer transformation during immunotherapy with nivolumab: A case report.
abstract: 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.
authors.affiliation: Division of Respiratory Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan; Department of Respiratory Medicine, Hyogo Prefectural Amagasaki General Medical Center, Hyogo, Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Imakita
authors.affiliation: Division of Respiratory Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Division of Respiratory Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Kanai
authors.affiliation: Division of Clinical Pathology, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Terashima
authors.affiliation: Division of Respiratory Medicine, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Mio
keywords: Immune checkpoint inhibitor; NSCLC; Nivolumab; SCLC transformation