Long-term follow-up at ESMO 2026
Rakuten Medical presented long-term follow-up results from the Phase 1b/2 ASP-1929-181 study, which tested ASP-1929 photoimmunotherapy in combination with pembrolizumab in patients with recurrent and/or metastatic head and neck squamous cell carcinoma, Rakuten Medical said. The data were shown as an e-poster on 23 October 2026 at 8:00 a.m. CET at the European Society for Medical Oncology Congress 2026 in Madrid. The analysis used a data cutoff of 10 February 2026 and extended follow-up by 21.4 months, to a median of 53.1 months from 31.7 months in the earlier report.
Survival and response figures
The study enrolled 19 patients, and 17 were included in the efficacy-evaluable analysis. Median overall survival was 28.2 months, with estimated rates of 47.1% at 36 months and 35.3% at 48 months. Five patients (29%) achieved a complete response, and four of them remained alive with follow-up ranging from more than 42 months to more than 60 months. Median duration of response was 44.3 months at the cutoff, and four responders remained free of subsequent anticancer therapy after discontinuing study treatment. Exploratory analyses across subgroups defined by baseline HPV status, PD-L1 CPS expression and tumour size showed generally consistent efficacy and safety findings, and no new safety signals were observed.
Phase 3 trial and a 2028 filing
Rakuten Medical said it is running the global Phase 3 ASP-1929-381 study, which evaluates the same combination as a first-line treatment for locoregional recurrent head and neck cancer. The company said the long-term findings are exploratory and should be interpreted in light of the study's limitations, including its small sample size and limited patient numbers in some subgroup analyses, and that they support continued investigation in the Phase 3 trial. After that trial is completed, the company aims to submit a Biologics License Application for ASP-1929 to the U.S. Food and Drug Administration in 2028.
