Complete tumor response of a locally advanced lung large-cell neuroendocrine carcinoma after palliative thoracic radiotherapy and immunotherapy with nivolumab

•Complete tumor response of an L-LCNEC to radiotherapy and immunotherapy.•There is a possible synergetic effect of radiotherapy with immunotherapy.•Immunotherapy seems to be efficient in carcinoma-LCNEC.•Immunotherapy could be effective in the neoadjuvant setting in L-LCNEC. Lung large-cell neuroendocrine carcinoma (L-LCNEC) is a rare subset of lung carcinoma associated with poor overall survival. Due to its rarity, little has been established about its optimal treatment in the advanced stage. We report the case of a 41-year-old woman diagnosed with an unresectable locally advanced L-LCNEC who presented an impressive tumor response to immunotherapy with nivolumab after non-curative thoracic radiotherapy. Salvage surgery was then performed, and pathologic analysis of the resected piece revealed the absence of residual viable tumor cells. Based on this case report, we discuss the literature regarding the efficacy of inhibitors of programmed death-1 protein (PD-1) in L-LCNEC and their use in association with radiotherapy and in the neoadjuvant setting.