Forlong Biotechnology, a clinical-stage biotech company developing cytokine therapies, announced it has received the first milestone payment under its licensing and collaboration agreements following a partner's IND submission for a protein therapy incorporating the company's proprietary Fbody® technology platform to China's National Medical Products Administration.
Partnership Evolution and Financial Structure
The milestone payment represents a significant development in Forlong's collaboration strategy that began in 2020. Initially, Forlong partnered with Shell BioTech, a Chinese CDMO, to leverage the Fbody® Technology Platform for developing long half-life peptide therapy for a third party. In 2025, the partnership evolved into a formal licensing agreement with the third party for selected protein therapy candidates incorporating Fbody®, with restructured terms including upfront payments, milestone payments, and royalties on future product sales.
Fbody® Technology Platform
Fbody® Long-acting Technology represents one of Forlong's synthetic immunology platforms. The technology features a single-chain Fc engineered to maintain FcRn affinity while eliminating binding of FcγRs and complement systems, specifically designed to optimize protein half-life and biodistribution.
Clinical Pipeline Progress
Forlong's lead clinical candidate FL115, an interleukin-15 (IL-15) superagonist incorporating Fbody®, is currently in multiple clinical studies across China and the United States. The therapy has demonstrated a favorable safety profile and preliminary clinical responses in patients with advanced solid tumors. FL115 is advancing to combination therapy with PD-(L)1 antibodies in Phase I trials for patients with advanced solid tumors and combination therapy with Bacillus Calmette-Guérin (BCG) in Phase II trials for patients with nonmuscle invasive bladder cancer (NMIBC).
The company's second candidate, FL116, is a human anti-programmed cell death protein 1 (PD-1) antibody site-specifically fused to an interleukin-18 (IL-18) variant with minimal binding affinity to the IL-18 binding protein (IL-18BP). This candidate has demonstrated potent tumor-killing efficacy in multiple in vivo tumor models sensitive or resistant to immune checkpoint inhibitors.
Strategic Validation
"We are excited to see another Fbody® fusion protein therapy advancing into clinic, a significant milestone for our synthetic immunology platforms," said Dong Wei, Ph.D., Chief Executive Officer of Forlong Biotechnology. "FL115's best-in-class potential in the challenging IL-15 superagonist class first showcased unique properties of Fbody®, and this milestone further validates its ability to enhance profiles for variety of proteins beyond cytokines, and success of our out-licensing strategy and its ability to drive real-world impact through partnerships."
Technology Platform Portfolio
Forlong has established four proprietary synthetic immunology platforms: the Fbody® Long-acting Technology Platform, Fc engineering platform, Syntokine® Synthetic Cytokine Platform, and AI-driven Intelligent Biomolecular Discovery Platform. This diversified approach positions the company to address various therapeutic challenges in cytokine therapy development.
