Quad-shot-immunotherapy: quad-shot radiotherapy with pembrolizumab for advanced/recurrent head and neck cancer.

Effective treatments for advanced/recurrent head and neck squamous-cell carcinoma are limited. For cases not curable by conventional local therapies, the immune checkpoint inhibitor pembrolizumab shows modest response rates. Quad-shot, a hypofractionated palliative radiotherapy regimen (14.8 Gy in four twice-daily fractions), can provide symptomatic relief, contributes to local control and may potentiate the effects of immune checkpoint inhibitors. In this study, 15 patients with advanced/recurrent head and neck squamous-cell carcinoma will be treated with pembrolizumab combined with up to three administrations of quad-shot before cycles four, eight and 13. Outcomes include disease response, survival and treatment toxicity. Correlative multiomics analysis of blood and saliva will identify molecular biomarkers of response to immune checkpoint inhibitor and the immune-related impact of quad-shot. Clinical trial registration : This study (WFBCCC 60320) is registered on NCT04454489 (ClinicalTrials.gov).