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

Abstract

Purpose

To report a single institutional experience with re-irradiation and concurrent pembrolizumab for local-regionally recurrent squamous cell carcinoma of the head and neck.

Method and materials

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.

Results

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.

Conclusion

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.