ABSTRACT
The patient was 67-year-old woman with non-small cell lung carcinoma (squamous cell carcinoma, T2bN2M1a, Stage IVA) who was started on fifth-line therapy with nivolumab, an immune checkpoint inhibitor. Although tumor biopsy was negative for programmed cell death ligand 1 (PD-L1), the tumor size decreased. Nivolumab had to be discontinued due to suspected immune-related adverse events (i.e., skin rash and enteritis symptoms), but the tumor size reduction persisted after discontinuation and complete response was maintained for ≥ 8 months. After disease recurrence, nivolumab therapy was restarted. The tumor size decreased, and partial response was achieved and maintained. The disease was successfully controlled for ≥ 2 years (27 courses of nivolumab), when nivolumab therapy was again discontinued due to skin rash. Despite the PD-L1-negative status, the patient achieved long-term response to nivolumab therapy. The immune-related adverse events in this case were comparable between the initial and reintroduced nivolumab therapy, suggesting that nivolumab is safe to administer over the long term.