Gyre Therapeutics Announces Publication of Protocol for Phase 3 Trial Evaluating F351 for CHB-Associated Liver Fibrosis

Gyre Therapeutics recently announced the publication of the manuscript titled Hydronidone for the Treatment of Liver Fibrosis Associated with Chronic Hepatitis B: Protocol for a Phase 3 Randomized Trial in the Journal of Clinical and Translational Hepatology. This publication details the full protocol for the pivotal Phase 3 trial to support the use of hydronidone in Chinese patients with liver fibrosis associated with chronic hepatitis B (“CHB”). The published protocol outlines patient inclusion criteria, randomization and blinding processes, key assessments, and the statistical analysis plan.

The randomized, double-blind, placebo-controlled, multicenter Phase 3 trial (NCT05115942) completed the enrollment of 248 patients across 44 clinical research hospitals in the People’s Republic of China (“PRC”) in October 2024. Patients were randomized 1:1 to receive either F351 or placebo in addition to entecavir antiviral basic therapy for CHB. The primary endpoint is a decrease in liver fibrosis (as measured by the Ishak Scoring System) by at least one stage after 52 weeks of treatment relative to baseline.

The PRC’s National Medical Products Administration (NMPA) designated F351 as a Breakthrough Therapy in 2021. Gyre expects to report topline results from this Phase 3 trial in the second quarter of 2025.

F351 is a next-generation anti-fibrotic compound and a structural analogue of Pirfenidone, the first approved treatment for idiopathic pulmonary fibrosis (IPF) in Japan, the European Union, the United States and the PRC. F351’s dual mechanism has been shown to inhibit in vitro p38γ kinase activity and TGF-β1-driven collagen overproduction—both key drivers of liver fibrosis. F351 specifically targets hepatic stellate cells (“HSCs”), which are central to the progression of fibrosis. In preclinical studies, it has shown strong anti-proliferative and anti-fibrotic effects on HSCs. These effects have been validated across multiple in vivo models of liver fibrosis, including CCl₄-induced liver fibrosis in mice, DMN- and HSA-induced liver fibrosis in rats, and a mouse model of MASH fibrosis (a form of MASH with fibrosis) induced by CCl₄ plus a Western high-fat diet. Together, these results highlight F351’s potential as a differentiated treatment for liver fibrosis, with a unique mechanism and strong preclinical and clinical evidence supporting its advancement into later-stage development.

Gyre Pharmaceuticals is a commercial-stage biopharmaceutical company committed to the research, development, manufacturing and commercialization of innovative drugs for organ fibrosis. Its flagship product, ETUARY (Pirfenidone capsule), was the first approved treatment for IPF in the PRC in 2011 and has maintained a prominent market share (2024 net sales of $105.8 million). In addition, Gyre Pharmaceuticals is evaluating F351 in a Phase 3 clinical trial in CHB-associated liver fibrosis in the PRC, which is expected to readout topline data by Q2 2025. F351 received Breakthrough Therapy designation by the NMPA Center for Drug Evaluation in March 2021. Gyre Pharmaceuticals is also developing treatments for PD, DKD, COPD, PAH and ALF/ACLF. In October 2023, Gyre Therapeutics acquired an indirect majority interest in Gyre Pharmaceuticals (also known as Beijing Continent Pharmaceuticals Co., Ltd.).

Gyre Therapeutics is a biopharmaceutical company headquartered in San Diego, CA, with a primary focus on the development and commercialization of F351 (Hydronidone) for the treatment of MASH-associated fibrosis in the U.S. Gyre’s development strategy for F351 in MASH is based on the company’s experience in MASH rodent model mechanistic studies and CHB-induced liver fibrosis clinical studies. Gyre is also advancing a diverse pipeline in the PRC through its indirect controlling interest in Gyre Pharmaceuticals, including ETUARY therapeutic expansions, F573, F528, and F230.