ZSP-1601

Given the global prevalence and rising incidence of metabolic dysfunction-associated steatotic liver disease (MASLD), the absence of licensed medications is striking. A deeper understanding of the heterogeneous nature of MASLD has recently contributed to the discovery of novel groups of agents and the potential repurposing of currently available medications. MASLD therapies center on four major pathways. Considering the close relationship between MASLD and type 2 diabetes, the first approach involves antidiabetic medications, including incretins, thiazolidinedione insulin sensitizers, and sodium-glucose cotransporter 2 inhibitors. The second approach targets hepatic lipid accumulation and the resultant metabolic stress. Agents in this group include peroxisome proliferator-activated receptor agonists (e.g., pioglitazone, elafibranor, saroglitazar), bile acid-farnesoid X receptor axis regulators (obeticholic acid), de novo lipogenesis inhibitors (aramchol, NDI-010976), and fibroblast growth factor 21/19 analogs. The third approach focuses on targeting oxidative stress, inflammation, and fibrosis. Agents in this group include antioxidants (vitamin E), tumor necrosis factor α pathway regulators (emricasan, pentoxifylline, ZSP1601), and immune modulators (cenicriviroc, belapectin). The final group targets the gut (IMM-124e, solithromycin). Combination therapies targeting different pathogenetic pathways may provide an alternative to MASLD treatment with higher efficacy and fewer side effects. This review aimed to provide an update on these medications.

Background: The pharmacokinetics (PK), safety, and tolerability profiles of ZSP1601, a first-in-class pan-phosphodiesterase (PDE) inhibitor, were evaluated in healthy Chinese volunteers.Research design and methods: This Phase 1a study consisted of a double-blinded, randomized, placebo-controlled single ascending dose (SAD) (25 to 350 mg), multiple ascending doses (MAD) (50 or 100 mg QD), and a two-period crossover food effect study (100 mg).Results: ZSP1601 was quickly absorbed, with maximum plasma concentrations (C_max) reached at 1.25 to 2.50 h (median T_max). The exposures exhibited dose-proportional increases, while the mean half-life (t1/2) ranged from 6.34-8.64 h. Steady-state was reached within seven days in the MAD study. The mean steady trough concentrations were 423 and 588 ng/mL, respectively. ZSP1601 accumulation was low, with ratios ≤ 1.5. The bioavailability of ZSP1601 was equivalent under fasted and fed states. All adverse events (AEs) were assessed as mild or moderate, with headaches as the most common. The highest single doses (275 and 350 mg) yielded more AEs, yet the rates were similar with the placebo cohorts in the MAD study.Conclusions: The safety and PK profiles of ZSP1601 support further efficacy evaluation in nonalcoholic steatohepatitis patients.Trial registration: The trial is registered at ClinicalTrials.gov (CT.gov identifier: NCT03392779).