Gyre Therapeutics has announced that China's National Medical Products Administration (NMPA), through its Center for Drug Evaluation (CDE), has granted priority review designation to a New Drug Application for Hydronidone (F351) as a treatment for chronic hepatitis B (CHB)-induced liver fibrosis. If the NDA is formally submitted and the drug subsequently cleared, Hydronidone would become the first therapy approved anywhere in the world specifically indicated for reversing liver fibrosis caused by CHB. The company, which is headquartered in San Diego and operates through its majority-owned subsidiary Gyre Pharmaceuticals in China, disclosed the milestone on March 17, 2026.
The filing seeks conditional approval for Hydronidone in patients with CHB-associated liver fibrosis, including early compensated cirrhosis. Gyre Therapeutics said the priority review designation followed a pre-NDA communication meeting with CDE announced on January 5, 2026, and that a formal NDA submission is planned in the near future. Under China's priority review pathway, established in 2017, the NMPA allocates additional evaluation resources and accelerates the review timeline for drugs deemed to have clinical value. Hydronidone previously received Breakthrough Therapy designation from CDE in March 2021. The company has not disclosed a specific target date for a regulatory decision. Gyre also indicated that a confirmatory Phase IIIc clinical trial (NCT07412236) would be initiated to support eventual full approval in China.
The NDA is supported by data from a pivotal Phase III trial (NCT05115942) that enrolled 248 patients with CHB-associated liver fibrosis (Ishak fibrosis stage three or higher) across 39 hospitals in China. The study evaluated Hydronidone administered orally over 52 weeks alongside background nucleos(t)ide analogue antiviral therapy. According to the company, the trial met its primary endpoint, demonstrating a statistically significant rate of fibrosis regression of at least one Ishak stage compared with placebo (P=0.0002). Hydronidone is a structural analogue of pirfenidone that attenuates hepatic stellate cell activation by suppressing TGF-β1-induced signal transduction, including reduced p38γ phosphorylation and upregulated Smad7 expression, thereby disrupting canonical TGF-β/Smad signaling and reducing fibrotic gene expression. A long-term extension study (NCT05905172) is currently recruiting, with completion expected in 2028. Detailed safety data from the pivotal trial have not been publicly disclosed.
The filing enters a therapeutic space defined by absence. No drug is currently approved in any major market for the direct treatment of liver fibrosis caused by CHB. Existing standard of care relies on nucleos(t)ide analogues such as entecavir, tenofovir disoproxil fumarate, and tenofovir alafenamide, which suppress viral replication and may slow fibrosis progression indirectly but are not indicated for fibrosis reversal. Studies have shown that fibrosis regression under antiviral therapy alone is incomplete in a substantial proportion of patients, particularly those with advanced disease, leaving residual risk of hepatocellular carcinoma and hepatic decompensation. The World Health Organization estimates approximately 254 million people worldwide were living with CHB infection in 2022, with China bearing a disproportionate burden. The only approved antifibrotic in liver disease is resmetirom (Rezdiffra), cleared by the US FDA in March 2024 for metabolic dysfunction-associated steatohepatitis with fibrosis, a condition with a distinct etiology and mechanism from CHB. No other innovative molecules targeting CHB-induced fibrosis are in late-stage clinical development, making Hydronidone the sole candidate approaching regulatory consideration for this indication.
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