Safety and Efficacy Findings From a Phase Ib/II Study of ASP-1929 Photoimmunotherapy With Pembrolizumab in Recurrent and/or Metastatic Head and Neck Squamous Cell Carcinoma.

Background: ASP-1929 photoimmunotherapy-cetuximab conjugated to IRDye 700DX and red light (690 nm) for localized drug activation-results in rapid, selective cell killing.

Methods: This phase Ib/II open-label study evaluated ASP-1929 photoimmunotherapy plus pembrolizumab in patients with recurrent/metastatic HNSCC (≥ 1 accessible lesion, PD-L1 combined positive score ≥ 1, ineligible for standard locoregional therapy). Primary objectives were safety/tolerability and objective response rate (ORR). Secondary objectives included overall survival (OS) and progression-free survival (PFS).

Results: Eighteen patients (median age 63 years, 74% male) comprised the photoimmunotherapy-evaluable population. The confirmed ORR was 27.8% (95% CI 9.7-53.5); four of five responders had complete responses (95% CI, 6.4-47.6). Median OS was 25.6 months (95% CI, 14.6-not evaluable); median PFS was 2.9 months (95% CI, 1.4-14.6). The most common serious adverse reactions were dysphagia and tongue edema (each n = 2; 10.5%).

Conclusions: ASP-1929 photoimmunotherapy plus pembrolizumab was generally tolerable, with promising efficacy in patients with recurrent/metastatic HNSCC.