Eisai Co., Ltd. and Shanghai Henlius Biotech have signed an exclusive commercialization and co-exclusive development and manufacturing licensing agreement for the anti-PD-1 antibody serplulimab in Japan, marking a significant step in expanding access to the immunotherapy in one of Asia’s largest oncology markets.
Serplulimab, developed by Henlius, is a monoclonal antibody designed to target the PD-1 immune checkpoint pathway, enabling the immune system to better recognize and attack cancer cells. The therapy is already marketed as HANSIZHUANG in China and Hetronifly in the European Union. It has received approvals in China for multiple cancers, including squamous non-small cell lung cancer (sqNSCLC), extensive-stage small cell lung cancer (ES-SCLC), non-squamous non-small cell lung cancer, and esophageal squamous cell carcinoma. In the EU, it is approved for ES-SCLC and became the first anti-PD-1 therapy authorized as a first-line treatment for that indication.
Henlius is currently conducting a Phase II bridging study for ES-SCLC in Japan and plans to file for regulatory approval in fiscal year 2026 using both local data and global Phase III trial results. The companies are also developing the therapy for non-microsatellite instability-high (non-MSI-High) metastatic colorectal cancer through a multinational Phase III trial. Additional studies, including one in perioperative gastric cancer, are planned.
The companies highlighted the significant unmet medical need in Japan, where roughly 13,000 patients are diagnosed with ES-SCLC and about 28,000 with non-MSI-High metastatic colorectal cancer annually. These conditions are often aggressive and difficult to treat, underscoring the importance of new immunotherapy options.
Under the agreement, Eisai receives exclusive commercialization rights in Japan, while Henlius will act as the marketing authorization holder and continue clinical development. Eisai will pay Henlius an upfront payment of $75 million, regulatory milestone payments of up to $80.01 million, and potential sales milestones of up to $233.3 million, along with double-digit royalties on product sales.
Henlius CEO Jason Zhu said the partnership combines Henlius’ biologics innovation with Eisai’s strong local commercialization capabilities to accelerate patient access. Eisai executive Toshihiko Yusa added that the company aims to deliver the therapy quickly to Japanese patients and expects it to become a promising treatment option for difficult-to-treat cancers.
The collaboration reflects growing cross-border partnerships in oncology as companies seek to globalize immunotherapies and address unmet needs across regional markets.