Rakuten Medical’s Anti-PD-L1 Antibody-IR700 Conjugate, RM-0256, Selected for AMED Funding

On June 4, 2025 Rakuten Medical, Inc., a global biotechnology company developing and commercializing Alluminox platform-based photoimmunotherapy, reported that its third drug candidate, RM-0256, has been selected for funding by the Japan Agency for Medical Research and Development (AMED) under its Support Program for Orphan Drug prior to the Designation (Press release, Rakuten Medical, JUN 4, 2025, View Source [SID1234653727]).

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RM-0256 is a novel antibody conjugate composed of IRDye700DX (IR700)—a light-activatable dye for which Rakuten Medical holds exclusive global manufacturing and supply rights—and a proprietary anti-PD-L1 monoclonal antibody. The AMED funding will support the clinical development of RM-0256 photoimmunotherapy for unresectable, advanced, or recurrent malignant epithelial tumors.

In Japan, malignant epithelial tumors affect approximately 22,000 individuals annually1. While systemic therapies, including chemotherapy and immune checkpoint inhibitors, are currently the mainstay of treatment for unresectable advanced or recurrent cases, patients who develop resistance to these treatments face limited treatment options, which underscores the urgent need for novel therapeutic approaches.

RM-0256 targets Programmed Cell Death Ligand 1 (PD-L1), a key immune checkpoint protein that allows tumors to evade immune detection by binding to PD-1 receptors on activated T cells. PD-L1 is widely expressed in various solid tumors—including melanoma, ocular melanoma, lung, urothelial, gastrointestinal, gynecological, breast, and head and neck cancers2—as well as on immunosuppressive cells within the tumor microenvironment.

Pre-clinical studies of PD-L1-targeted photoimmunotherapy have suggested three complementary mechanisms of action3:

1) Direct depletion (necrosis) of PD-L1-expressing tumor cells;
2) Activation of anti-tumor immunity through the elimination of PD-L1–expressing immunosuppressive cells;
3) Checkpoint blockade, by inhibiting PD-L1/PD-1 interaction, potentially enhancing systemic immune responses.

With the support of AMED funding, Rakuten Medical is accelerating the development of RM-0256 photoimmunotherapy as a novel, multimodal cancer therapy that may induce both local and systemic anti-tumor effects.