Rapafusyn Pharmaceuticals Secures $44 Million Series A Financing to Advance Its Non-Degrading Molecular Glue Drug Discovery Platform

On September 4, a leader in the discovery and development of non-degradable molecular glue therapeuticsRapafusyn Pharmaceuticals(hereinafter referred to as “Ruifuxin” or “Rapafusyn”) announced the successful completion of an oversubscribed Series A financing round, with total proceeds amounting to USD 44 million, including the previously secured USD 24 million. New investors in this roundBioTrack CapitalandYonjin Capital, with existing shareholders3E Bioventures、Proxima CapitalandLapamCapitalJoint participation.

Rapafusyn, co-founded by Professor Liu Jun of the Johns Hopkins University School of Medicine (a pioneer in the field of molecular glues), has receivedJiangsu Tianqin Investment Co., Ltd.initial funding support.

This round of financing will accelerate the advancement of Rapafusyn’s pipeline addressing high unmet clinical needs in the fields of oncology, immunology, nephrology, and pain management.Its core technology, RapaGlues™, is a unique non-degradable molecular glue focused on overcoming the challenge of “undruggable targets.” By binding to FKBP12, a protein naturally abundant in cells, RapaGlues™ brings this protein into proximity with the target, thereby inducing novel protein–protein interactions that effectively inhibit target function and open new avenues for targeted drug development.

The RapaGlue™ platform targets traditionally undruggable targets—such as protein-protein interactions, transcription factors, SLC transporters, and ion channels—through the rational design of non-degradable macrocyclic molecular glues (RapaGlues™). Its core mechanism leverages FKBP12-mediated ternary complex formation, integrated with DNA-encoded libraries (DEL) and artificial intelligence/machine learning (AI/ML) tools, to achieve industry-leading efficiency in candidate discovery. The platform has been validated across multiple pipelines; notably, its ENT1 inhibitor project significantly reduced inflammatory factor expression in kidney disease models and is currently advancing toward the pre-IND stage. Meanwhile, the company is collaborating with global pharmaceutical companies to develop innovative therapies, utilizing a DNA-encoded library (DEL) comprising over 8 billion molecules.

Dr. Sean Hu, CEO of Rapafusynstated, “This round of financing will accelerate the development of the RapaGlue™ platform, delivering transformative therapies to patients with urgent unmet medical needs. The participation of BioTrack Capital and YONGJIN GROUP serves as a strong endorsement of the platform’s capability to tackle undruggable targets.”

Dr. Liu Qianye, Founding Partner of 3E Bioventures“Rapafusyn and the RapaGlue™ platform are redefining the boundaries of drug discovery through novel macrocyclic molecule technology. This platform can overcome the limitations of traditional small molecules and degrader drugs, targeting previously undruggable targets—this expanded capability is truly exciting to me!”

Song Haolin, Partner at Proxima Capital, and Li Jian, Partner at LapamCapitalstated: "As existing shareholders, we look forward to collaborating with new investors to help accelerate breakthroughs in the Rapafusyn platform and pipeline."

Chen Kai, Vice President of BioTrack Capitalstated: "Rapafusyn's non-degrading molecular glue platform provides a novel therapeutic pathway for undruggable targets, demonstrating significant differentiated value in areas of unmet clinical need."

Wen Chen, Partner at Yongjin Capitalstated, “The RapaGlue™ platform has demonstrated exceptional progress in the discovery of high-potential drug candidates, backed by a team with profound professional expertise. This round of investment was a natural and inevitable choice.”

BioTrack Capital, established in 2017, is a venture capital firm dedicated to investing in and incubating high-quality early-stage enterprises in China’s healthcare sector. Its investment scope encompasses biotechnology, medical devices, and interdisciplinary healthcare fields, such as AI and digital health, as well as consumer healthcare.

BioTrack Capital’s professional investment team possesses deep and complementary industry expertise in R&D, clinical operations, consulting, and investment.

Yonjin Capital is a leading international investment firm focused on early- to mid-stage life science companies in the fields of therapeutics, diagnostics, and medical devices. Leveraging its global perspective, deep industry expertise, and extensive resource network, the Yonjin Capital team helps portfolio companies achieve exceptional results. Yonjin Capital serves as the North American and European investment arm of Yonjin Group and is affiliated with Yonghua Capital, headquartered in Shanghai, China.

Rapafusyn Pharmaceuticals is an innovative biotechnology company focused on the development of non-degradative molecular glue technologies. Its scientific founder is Professor Jun Liu from the Johns Hopkins University School of Medicine, one of the pioneering figures in the field of molecular glues. The company’s proprietary RapaGlue™ technology leverages the abundant intracellular protein FKBP12 to induce interactions between target proteins and FKBP12, thereby modulating disease targets that are traditionally difficult to address with conventional drugs. To date, Rapafusyn has successfully identified high-affinity and highly selective candidate drug molecules against various traditionally “undruggable” targets, including protein–protein interactions (PPIs), transcription factors, and transmembrane proteins. Furthermore, RapaGlue™ molecular glue molecules, designed through rational drug design, generally exhibit excellent inherent membrane permeability and other favorable drug-like properties.