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Trial result
Head and neck cancer

Pembrolizumab (PD-1) + Quad‑Shot RT (14.8Gy/4fx) Delivers 47% ORR in Recurrent/Metastatic HNSCC

Trial ID
NCT04454489 on ClinicalTrials.gov
Cancer type
Mucosal Head and Neck Cancer
Published in
New in Oncology - Aug 6, 2026

Pembrolizumab is an anti–PD‑1 immune checkpoint inhibitor; quad‑shot radiotherapy (QSRT) is a low-dose hypofractionated regimen (14.8Gy in four 3.7Gy fractions BID over 2 days) intended to improve local control and potentially augment immunogenic tumor killing. In this single-center, single-arm Phase 2 trial in recurrent, unresectable, or metastatic (RUM) HNSCC eligible for QSRT (enrolled Feb 2021–May 2024), ORR was 47% (95% CI, 21%–73%) in response-evaluable patients (n=15), with median PFS 9.2 months and median OS 14.9 months in treated patients (n=20). Grade 3–4 AEs occurred in 6 and 2 patients, respectively, with patient-reported AEs not worsening over time; efficacy looks higher than historical pembrolizumab monotherapy in R/M HNSCC (KEYNOTE-048 ORR ~19% and median OS ~11.6 months in the total population), but the cross-trial comparison is confounded by this study’s small n, single-site selection, and requirement for a QSRT-amenable target lesion (NCT04454489).

Take home

If randomized data confirm this signal, adding a short-course, palliative-intent “quad-shot” to pembrolizumab could be a practical way to raise response rates (and maybe durability) in a population where PD‑1 alone often underperforms—though patient selection and local-site effects vs true systemic benefit still need to be disentangled.

Source: Read the original publication

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