Raynovent Announces Positive Topline Results from Phase 2b Trial of ZSP1601 in Patients with Biopsy-Confirmed Metabolic Dysfunction-Associated Steatohepatitis (MASH)
Raynovent Announces Positive Topline Results from Phase 2b Trial of ZSP1601 in Patients with Biopsy-Confirmed Metabolic Dysfunction-Associated Steatohepatitis (MASH).
· Study Met Primary Efficacy Endpoint: Both Dose Groups Achieved Significantly Higher Response Rates Compared to Placebo at Week 48
· ZSP1601 Demonstrated Robust Anti-Fibrotic Effect, with Between-Group Differences of 29.50% and 10.60% in Fibrosis Improvement (≥1 point and ≥2 points, respectively)
· The FirstPan Phosphodiesterase (PDE) Inhibitor to Show Significant Histologic Benefit in a Phase 2b MASH Trial
· The Result Supports Progression to Phase 3 Development
GUANGZHOU, China, May 8, 2026 — Raynovent, a commercial-stage biotech company focused on the development of innovative therapies for metabolic and liver diseases, today announced positive topline data from its Phase 2b clinical trial evaluating ZSP1601, a first-in-class pan-phosphodiesterase (PDE) inhibitor, in patients with biopsy-confirmed metabolic dysfunction-associated steatohepatitis (MASH) and fibrosis. The data will be presented at an upcoming medical meeting.
The Phase 2b study successfully achieved its primary efficacy endpoint. At Week 48, based on the modified intent-to-treat (mITT) analysis set, the response rate—defined as the proportion of participants achieving either histologic improvement in MASH without worsening of fibrosis, or fibrosis improvement of ≥1 point without worsening of MASH—was 64.9% in the ZSP1601 100 mg BID group and 57.6% in the 50 mg BID group, compared with 32.5% in the placebo group (p<0.05 for each active dose versus placebo). The between-group differences relative to placebo were 31.85% and 27.37%, respectively.
Beyond the primary endpoint, ZSP1601 demonstrated robust anti fibrotic effects. At Week 48, in the ZSP1601 100 mg BID group, the placebo adjusted response rates for fibrosis improvement of ≥1 point and ≥2 points (without worsening of MASH) were 29.50% and 10.60%, respectively, both showing statistically significant benefit. ZSP1601 also rapidly reduced liver fat content, as measured by magnetic resonance imaging proton density fat fraction (MRI-PDFF), and improved liver enzyme biomarkers including ALT、AST、GGT, while exhibiting a favorable safety and tolerability profile.
"These positive Phase 2b results confirm that ZSP1601, as the first PDE inhibitor to demonstrate histologic benefit in a Phase 2b MASH trial, represents a promising new therapeutic approach for patients with MASH," said Dr. Xiaoxin Chen, Chairman of Raynovent, "The robust efficacy across multiple endpoints—anti-fibrosis, liver fat reduction, and liver enzyme improvement—coupled with its favorable safety profile, positions ZSP1601 as a potential cornerstone for combination therapy in MASH. ZSP1601 has demonstrated anti-fibrotic efficacy at 48 weeks comparable to injectable FGF21-based therapies, while offering the unique advantages of oral convenience and an excellent safety profile. We will maintain close communication with regulatory authorities to accelerate the Phase 3 clinical development of ZSP1601, while actively seeking global partners to jointly advance this globally competitive China-innovated drug to patients as soon as possible, contributing an original Chinese therapeutic solution. "
About the Phase 2b Study
The Phase 2b trial was a multicenter, randomized, double-blind, placebo-controlled study designed to evaluate the safety and efficacy of ZSP1601 in patients with biopsy-confirmed MASH. A total of 181 participants with histologically confirmed MASH were randomized to receive ZSP1601 50 mg BID, ZSP1601 100 mg BID, or placebo. The primary efficacy endpoint was the proportion of participants achieving a histologic response at Week 48, defined as MASH improvement without worsening of fibrosis, or fibrosis improvement of ≥1 point without worsening of MASH. The study was co-led by Professor Hou Jinlin from Nanfang Hospital, Southern Medical University, and Professor Niu Junqi from The First Hospital of Jilin University.
About ZSP1601
ZSP1601 is a first-in-class, orally administered pan-phosphodiesterase (PDE) inhibitor with a novel mechanism of action for the treatment of MASH. It holds global intellectual property rights. Preclinical studies across multiple MASH animal models demonstrated that ZSP1601 ameliorates hepatic inflammation, ballooning degeneration and necrosis, with prominent anti fibrotic effects, positioning it as a potential backbone for combination therapy. The previously completed Phase Ib/IIa trial showed that after 28 days of treatment, ZSP1601 significantly reduced serum transaminase levels and liver fat content compared with placebo, along with declining trends in non-invasive fibrosis markers and biomarkers. The results of the Phase Ib/IIa study were published in Nature Communications.