Remarkable response of nivolumab‐refractory lung cancer to salvage chemotherapy

Promising outcomes of salvage chemotherapy after nivolumab therapy have been reported; however, little is known about the detailed clinical and immunologic features in lung cancer patients in whom nivolumab is unsuccessful. We report two cases of nivolumab‐refractory lung cancer, in which chemotherapy resulted in rapid regression of the lung cancer. Upon initial diagnosis, the biopsy specimens showed PD‐ligand 1 (PD‐L1)‐expressing cancer cells, accompanied by tumor‐infiltrating lymphocytes with a favorable CD8/CD4 ratio. Immunosuppressive regulatory T cells and cells positive for TIM‐3 were also observed. Physicians should take caution in treating lung cancer patients after progression on nivolumab. Further studies with a large cohort are warranted to identify the patients that may benefit from salvage chemotherapy.