Rakuten Medical Presents Long-Term Follow-up Results of ASP-1929 Photoimmunotherapy in Combination with Pembrolizumab for R/M HNSCC at ESMO 2026

• Median DOR of 44.3 months supports durability of response
• 4-year overall survival rate of 35.3% and median OS of 28.2 months suggest meaningful long-term survival
• Long-term survival of 42+ - 60+ months observed among complete responders

SAN DIEGO, Oct. 23, 2026 /PRNewswire/ -- Rakuten Medical, Inc., a global biotechnology company developing and commercializing Alluminox® platform-based photoimmunotherapy, today announced the presentation of long-term follow-up results from the Phase 1b/2 ASP-1929-181 study (NCT04305795), which evaluated ASP-1929 photoimmunotherapy in combination with pembrolizumab in patients with recurrent and/or metastatic head and neck squamous cell carcinoma (r/m HNSCC), at the European Society for Medical Oncology (ESMO) Congress 2026 in Madrid, Spain. The data were presented as an e-poster on October 23, 2026 at 8:00 a.m. (CET).

Prior efficacy and safety findings from the ASP-1929-181 study showed durable clinical activity and a manageable safety profile after a median follow-up of 31.7 months. The current analysis extends follow-up by an additional 21.4 months to a median follow-up of 53.1 months and reports updated efficacy and safety outcomes, along with exploratory subgroup analyses by HPV status, PD-L1 CPS expression, and tumor size at baseline.

ASP-1929-181 Study Presentation at ESMO 2026
Title: Long-Term Results of ASP-1929 Photoimmunotherapy with Pembrolizumab in Patients with Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma
Poster: View/Download Poster [PDF]
Key Findings (Data cutoff: February 10, 2026): 

• The ASP-1929-181 study enrolled 19 patients with r/m HNSCC, and the long-term follow-up analysis included 17 efficacy-evaluable patients.
• Meaningful long-term survival was observed:
  • Median overall survival (OS) was 28.2 months.
  • Estimated OS rates were 47.1% at 36 months and 35.3% at 48 months.
  • Among five (29%) patients who achieved a complete response (CR), four remained alive with follow-up ranging from more than 42 months to more than 60 months.
• Durability of response was suggested by:
  • Median duration of response (DOR) was 44.3 months at the data cutoff.
  • Four responders remained free from subsequent anticancer therapy following discontinuation of study treatment.
• Exploratory analyses showed generally consistent efficacy and safety findings across subgroups defined by baseline HPV status, PD-L1 CPS expression, and tumor size.
• No new safety signals were observed.

Rakuten Medical is currently conducting the global Phase 3 ASP-1929-381 study (NCT06699212) evaluating ASP-1929 photoimmunotherapy in combination with pembrolizumab as a first-line treatment for locoregional recurrent HNSCC. These findings are exploratory and should be interpreted in light of the study's limitations, including the small sample size and limited patient numbers in some subgroup analyses. Nevertheless, the results support continued investigation of the ASP-1929-381 study. Following completion of this trial, Rakuten Medical aims to submit a Biologics License Application (BLA) for ASP-1929 to the U.S. FDA in 2028.

About Alluminox® platform
The Alluminox platform is Rakuten Medical's investigational technology platform that combines pharmaceuticals, medical devices, medical technology, and other peripheral technologies. Rakuten Medical is developing Alluminox platform-based photoimmunotherapy, which involves two key steps: 1) drug administration and 2) targeted illumination using medical devices. The drug component consists of a cell-targeting moiety conjugated to a light-activatable dye, such as IRDye® 700DX (IR700), that selectively binds to the surface of targeted cells, such as tumor cells. The device component consists of a light source that locally illuminates the targeted cells with red light (690nm) to transiently activate the drug. Rakuten Medical's pre-clinical data have shown that this activation elicits rapid and selective necrosis of targeted cells through a biophysical process that compromises the membrane integrity of the targeted cells. Therapies developed on the Alluminox platform may also result in local and systemic innate and adaptive immune activation due to immunogenic cell death of the targeted tumor cells and/or the removal of targeted immunosuppressive cells within the tumor microenvironment. Photoimmunotherapy was originally developed by Dr. Hisataka Kobayashi and his team at the National Cancer Institute in the United States. Outside Japan, Rakuten Medical's Alluminox platform-based photoimmunotherapy is investigational.

About ASP-1929
Rakuten Medical's first pipeline drug developed on its Alluminox® platform is ASP-1929, an antibody-dye conjugate comprised of the anti-epidermal growth factor receptor (EGFR) antibody cetuximab and IRDye® 700DX, a light activatable dye. ASP-1929 binds to EGFR, a cancer antigen expressed in multiple types of solid tumors, including head and neck, breast, lung, colorectal, prostate and pancreatic cancers. After binding to cancer cells, ASP-1929 is locally activated by illumination with red light (690 nm), emitted by a laser device system to produce a photochemical reaction. This reaction is believed to cause damage to the membrane of cancer cells, leading to selective necrosis of cancer cells. 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. ASP-1929 photoimmunotherapy in combination with pembrolizumab is currently under investigation in a global Phase 3 clinical trial as a first-line therapy for recurrent head and neck cancer. Outside Japan, ASP-1929 has not yet been approved for commercial use by any regulatory authority.

About Rakuten Medical, Inc. 
Rakuten Medical, Inc. is a global biotechnology company developing and commercializing Alluminox® platform-based photoimmunotherapy, which, in pre-clinical studies, has been shown to induce rapid and selective cell killing. Rakuten Medical's photoimmunotherapy is currently investigational outside Japan. Rakuten Medical is committed to its mission to conquer cancer by developing its pioneering treatments as quickly as possible to as many patients as possible all over the world. The company has offices in 5 countries/regions, including the United States, where it is headquartered, Japan, Taiwan, Switzerland and India. For more information, visit our website, LinkedIn and YouTube.

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