Lack of efficacy of an inhibitor of PDE4 in phase 1 and 2 trials of patients with nonalcoholic steatohepatitis.

Background & Aims: ASP9831 is a phosphodiesterase-4 inhibitor developed to treat nonalcoholic steatohepatitis (NASH); it showed potent anti-inflammatory and antifibrotic effects in preclinical studies. We evaluated the efficacy and safety of ASP9831 in patients with NASH.

Methods: In a phase 1 trial, we determined the optimal therapeutic window of ASP9831 in healthy volunteers and evaluated 2 doses (50 and 100 mg) in patients with NASH. Based on the positive outcomes of the phase 1 study, we performed a phase 2 trial to compare the biochemical effects of ASP9831 vs placebo. Patients with NASH were assigned randomly to groups given either 50 mg (n = 33) or 100 mg (n = 33) ASP9831 twice daily, or placebo (n = 30), for 12 weeks. The primary end point was the mean percentage change, from baseline to the end of ASP9831 administration, in serum level of alanine aminotransferase (ALT); secondary outcomes included changes in aspartate aminotransferase (AST) levels, ratio of AST:ALT, and various biomarkers of NASH.

Results: After 12 weeks of administration, there was no significant change in mean serum levels of ALT (P = .42) or AST (P = .20) or other biomarkers in any group, and no significant differences were observed among groups. Most adverse events were mild; gastrointestinal disorders occurred more frequently in the ASP9831 groups than the placebo group.

Conclusions: Despite a relevant mechanism of action, ASP9831 did not significantly alter the biochemical markers of NASH, compared with placebo, in a clinical trial. This highlights the difficulties of developing therapeutics for NASH and the need for more extensive preclinical testing of mechanisms of potential drug candidates. Clinicaltrialsregister.eu: 2005-001687-31; EudraCT numbers: 2007-002114-19.