Hyper-late major response after 5 years of nivolumab: role of treatment beyond progression in head and neck cancer.

Patients with recurrent/metastatic (R/M) platinum-refractory squamous cell carcinoma of the head and neck (SCCHN) have fewer treatment options and harbor an especially poor prognosis. Maintaining treatment with anti-PD1 agents beyond response evaluation criteria in solid tumors-defined disease progression (TBP) has been shown to be efficacious in several solid tumors, including head and neck cancer. We present the case of a platinum-refractory locally recurrent, PD-L1-negative hypopharyngeal carcinoma, that received second-line nivolumab which was then maintained beyond progression under the following criteria: no Eastern Cooperative Oncology Group performance status deterioration, no rapidly progressive disease, no severe toxicity, and evidence of overall treatment benefit. The patient achieved a partial response 8 months after starting second-line nivolumab, with progressive disease at 26 months, then followed by the first TBP with nivolumab lasting for 15 months due to a new tumor progression. A second TBP with nivolumab lasting for 7 months, was followed by a third TBP with nivolumab for 12 months and achieving a major tumor response. Treatment is still ongoing 60 months after starting nivolumab, with excellent tolerance to therapy. Maintaining anti-PD1 agents beyond progression is an efficacious treatment option for patients with R/M SCCHN, that may achieve very durable disease control and even late major responses.