Long-lasting shrinkage in tumor mass after discontinuation of nivolumab treatment.

We report the case of a 62-year-old man treated with nivolumab as fourth-line therapy for stage IV squamous cell carcinoma of the lung. Because of the onset of nivolumab-induced pneumonitis after 2 doses, nivolumab was discontinued. After discontinuation, the tumor gradually continued to decrease in size without any additional treatment for lung cancer. The patient obtained a long-lasting shrinking of the tumor over 6 subsequent treatment-free months after only 2 administrations of nivolumab. This type of response has not been seen for conventional anticancer drug treatments for NSCLC, and we speculate that a small group of patients with NSCLC will obtain sufficient efficacy from a few doses of nivolumab.