ASCO 2025: Rakuten Medical to Presents Updates of Phase 3 ASP-1929-381 Study

Study design
The ASP-1929-381 study is a multi-regional multi-center, randomized, open-label Phase 3 trial designed to assess the efficacy and safety of ASP-1929 photoimmunotherapy in combination with pembrolizumab as a first-line treatment for locoregional recurrent HNSCC without distant metastases.

The trial is expected to include 412 patients globally, randomized to either an experimental arm receiving ASP-1929 photoimmunotherapy in combination with pembrolizumab, or a control arm receiving the current pembrolizumab-based standard-of-care (SOC), where patients may receive pembrolizumab alone or in combination with chemotherapy according to the physician’s choice. The primary endpoint is Overall Survival (OS), with key secondary endpoints including Complete Response Rate (CRR) and Overall Response Rate (ORR).

ASCO 2025
“We are honored that our Trial in Progress poster has been accepted for presentation at ASCO 2025,” said Anastasios Maniakas, MD, PhD, Assistant Professor in the Department of Head and Neck Surgery and an investigator of the ASP-1929-381 study at The University of Texas MD Anderson Cancer Center.

“This Phase 3 study represents a significant step forward in evaluating the potential synergistic efficacy of ASP-1929 photoimmunotherapy and pembrolizumab as a first-line treatment for patients with recurrent HNSCC. We look forward to sharing our progress with the global oncology community and advancing innovative approaches for the treatment of patients facing this challenging disease.”

Patient enrollment in Taiwan
In addition to the current trial program, patient enrollment has been initiated in Taiwan as part of its global expansion of the Phase 3 ASP-1929-381 study. For this study over 10 clinical sites across the United States and Taiwan are actively enrolling patients. Additional sites are expected to be activated in both regions, with patient enrollment in Japan anticipated to begin shortly.

“We are pleased to be part of this global Phase 3 study and to contribute to the development of an innovative treatment approach like photoimmunotherapy,” noted Kai-Ping Chang, MD, PhD, Professor of the Department of Otolaryngology – Head & Neck Surgery and Principal Investigator of the ASP-1929-381 study at Chang Gung Memorial Hospital in Taiwan.

“Head and neck cancer ranks third in male cancer incidence and fourth in male cancer mortality in Taiwan [1]. Local recurrence or metastasis is one of the leading causes of death in these patients [2], and nearly half of those with recurrent or metastatic disease survive for less than one year [3]. By participating in this trial, we hope to help advance new therapeutic options that may prolong overall survival of patients with recurrent HNSCC, both in Taiwan and around the world.”

Presentation

• Title: A phase 3 randomized study of ASP-1929 photoimmunotherapy in combination with pembrolizumab versus standard of care in locoregional recurrent head and neck squamous cell carcinoma (HNSCC)
• Abstract Number: TPS6122
• Session: Poster Session – Head and Neck Cancer
• Date: Monday, June 2, 2025
• Time: 9:00 a.m. – 12:00 p.m., CDT
• First Author: Anastasios Maniakas, The University of Texas MD Anderson Cancer Center, TX, the U.S.
• Location: Exhibit Hall A, Poster Board # 523b

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Note:* In Japan, ASP-1929 received marketing approval from the Japanese Ministry of Health, Labor, and Welfare for unresectable locally advanced or recurrent head and neck cancer in September 2020, under the Sakigake Designation System and the Conditional Early Approval System. Outside Japan, ASP-1929 has not yet been approved for commercial use by any regulatory authority.