Case series of pleomorphic carcinomas of the lung treated with nivolumab.

Pleomorphic carcinoma (PC) of the lung is a rare type of non-small cell lung cancer, exhibiting aggressive behavior and resistance to chemotherapy and radiotherapy. A previous study reported that PCs expressed high levels of PD-L1, suggesting the potential efficacy of immune checkpoint inhibitors in these tumors. We retrospectively reviewed the clinical records of three patients with PC of the lung treated with nivolumab: a 59-year-old woman (Case 1), a 66-year-old man (Case 2), and an 83-year-old man (Case 3). PD-L1 was highly expressed in their tumor cells. Two cases showed a partial response with long progression-free survival. However, in Case 2, brain and bone metastases progressed during nivolumab treatment in spite of high PD-L1 expression. This case series indicates that nivolumab is effective to some extent for PC of the lung. However, the clinical course of patients treated with nivolumab should be carefully observed, even when PD-L1 is highly expressed.