Abstract
Atypical pulmonary carcinoid (APC) is a lung neuroendocrine neoplasm (NEN), whose treatment draws from management of gastrointestinal NENs and small-cell lung carcinoma. We present a patient with recurrent metastatic APC and persistent mediastinal lymphadenopathy refractory to cisplatin and etoposide. After pursuing alternative treatments, he returned with significant progression, including diffuse subcutaneous nodules, weight loss and worsening cough. New biopsy analysis demonstrated APC with low mutational burden, low Ki-67 and Programmed Death-Ligand 1 (PD-L1), and without microsatellite instability. We pursued combination nivolumab and ipilimumab treatment based on success of CheckMate 032 in small-cell lung cancer. The patient's symptoms dramatically responded within a month, with almost complete resolution of lymphadenopathy following four cycles. He has been successfully maintained on nivolumab for the last 18 months. This suggests combination immunotherapy may be beneficial in the treatment of metastatic APC, and that PD-L1 and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors may be valuable in treating tumours lacking traditional biomarkers.