Re-irradiation with concurrent pembrolizumab for local-regionally recurrent squamous cell carcinoma of the head and neck

To report a single institutional experience with re-irradiation and concurrent pembrolizumab for local-regionally recurrent squamous cell carcinoma of the head and neck. A total of 16 patients were treated with external-beam re-irradiation to median dose of 66 Gy with concurrent pembrolizumab for histologically confirmed local-regionally recurrent squamous cell carcinoma of the head and neck. All patients had measurable disease. Twelve (75 %) were male and four (25 %) were female. The median age at the time of recurrence was 56 years (range, 42–80 years). The median interval from completion of prior radiation to recurrent disease was 28 months (range, 6–50 months). Nine patients (56 %) were p16 positive; 7 patients (44 %) were p16 negative. With a median follow-up time of 20 months, the 1- and 2-year estimates of overall survival were 71 % and 56 %, respectively. Of the 16 patients who underwent re-irradiation, eleven (69 %) had a complete response and 3 (19 %) had a partial response. Two patients (13 %) had stable disease after re-irradiation, and none progressed during treatment. A total of 6 patients developed metastasis outside of the re-irradiated area. The 1- and 2-year estimates of progression-free survival were 61 % and 37 %, respectively. The prevalence of acute and late grade 3+ toxicity was 25 % and 19 %, respectively. Re-irradiation with pembrolizumab for patients with recurrent squamous cell carcinoma of the head and neck is safe and potentially effective. A prospective study is under development to better identify who might benefit the most from this approach. • Both re-irradiation and pembrolizumab are used in the management of local-regionally recurrent head and neck cancer. • The observed outcomes using re-irradiation with concurrent pembrolizumab compare favorably to historical controls. • Re-irradiation with pembrolizumab for recurrent cancer of the head and neck is safe and potentially effective.