Rapafusyn Pharmaceuticals has successfully closed an over-subscribed $44 million Series A financing round, marking a significant milestone for the Baltimore-based biotechnology company focused on developing non-degrading molecular glue therapeutics. The financing round welcomed new investors BioTrack Capital and Yonjin Capital, joining existing backers including 3E Bioventures Capital, Proxima Ventures Ltd., and Lapam Capital.
The company, co-founded by Professor Jun O. Liu of Johns Hopkins University School of Medicine—a pioneer in the molecular glue field—initially received funding support from Jiangsu Tianqin Investment Ltd. The Series A round includes $24 million that was previously committed, bringing the total raised to $44 million.
Revolutionary Drug Discovery Platform
The financing will accelerate advancement of Rapafusyn's broad drug pipeline, which addresses diseases of high unmet medical need across oncology, immunology, renal and pain disease areas. The company's proprietary RapaGlue™ platform represents a groundbreaking approach to accessing challenging or previously undruggable disease targets through non-degrading molecular glues.
The RapaGlue™ platform has demonstrated the ability to create highly cooperative non-degrading molecular glues with high cell membrane permeability. These compounds can modulate protein-protein interactions, transcription factors, SLCs/transporters, ion channels, enzymes, and other challenging targets. The platform integrates innovative machine learning and AI methods as integral components of target selection and drug candidate optimization, resulting in what the company describes as an industry-leading success rate at discovering relevant chemical matter for hard-to-drug targets.
Lead Program Shows Promise
Rapafusyn's lead program, a selective ENT1 inhibitor, is advancing toward IND-enabling studies after demonstrating compelling activity in renal disease models. This progress serves as a powerful validation of the RapaGlue™ platform's therapeutic potential. The company is also leveraging its DNA-encoded library of more than 8 billion non-degrading molecular glues in a collaboration with a global pharmaceutical partner.
The RapaGlue™ compounds are rationally designed and engineered to bind FKBP and form a ternary complex with the disease target protein, offering a promising avenue for modulating intricate protein-protein interactions. These compounds frequently exhibit cell permeability directly from the starting point, enhancing their potential for therapeutic development.
Industry Recognition and Investment Confidence
"With the successful closing of our Series A financing, we are positioned to propel the RapaGlue™ platform and to accelerate our mission to deliver transformative therapies to patients in need," commented Dr. Sean Hu, President and CEO of Rapafusyn. "We are pleased to have BioTrack Capital and Yonjin Capital join this financing round."
Dr. Karen Liu, a Founding Partner at 3E Bioventures, emphasized the platform's innovative approach: "Rapafusyn and the RapaGlue™ platform are rewriting what's possible in drug discovery with a new class of macrocyclic molecules. I am excited about the platform's ability to expand beyond traditional small molecules and recent degrader molecules to approach previously undruggable targets."
Kai Chen, Vice President of BioTrack Capital, highlighted the investment rationale: "We are thrilled to invest in Rapafusyn for the potential of their innovative non-degrading molecular glue platform. It stands out as a highly differentiated drug modality for previously undruggable disease targets which hold substantial promise for diseases with unmet need."
Wen Chen, Partner at Yonjin Capital, added: "The Rapafusyn team has made remarkable progress in discovering high potential drug candidates using their RapaGlue™ platform. We are also very impressed by Rapafusyn's operating and advisory teams and are delighted to join the Series A round."
Technical Innovation
The platform's technical foundation rests on both DNA-encoded libraries (DELs) and arrayed libraries of RapaGlues™ that form neo-PPIs to inhibit a protein from its native activity. The modular architecture enables structure-activity relationship (SAR) studies and subsequent optimization for potency, selectivity, and physicochemical properties to accelerate drug discovery and development.
