Multicenter, Randomized, Double-Blinded, Placebo-Controlled Phase II Study of Serelaxin in Japanese Patients With Acute Heart Failure

Background: Serelaxin, a recombinant form of human relaxin-2, is in development for treating acute heart failure (AHF) and a Phase II study in Japanese AHF patients was conducted. Methods and Results: A randomized, double-blind, placebo-controlled study of serelaxin at 10 and 30 mu g.kg(-1).day(-1) continuous intravenous infusion for up to 48 h, added to standard care for Japanese AHF patients. Primary endpoints were adverse events (AEs) through Day 5, serious AEs (SAEs) through Day 14, and serelaxin pharmacokinetics. Secondary endpoints included changes in systolic blood pressure (SBP) and cardiorenal biomarkers. A total of 46 patients received the study drug and were followed for 60 days. The observed AE profile was comparable between the groups, with no AEs of concern. Dose-dependent increase in the serum concentration of serelaxin was observed across the 2 dose rates of serelaxin. A greater reduction in SBP was observed with serelaxin 30 mu g.kg(-1).day(-1) vs. placebo (-7.7 [-16.4, 1.0] mmHg). A greater reduction in NT-proBNP was noted with serelaxin (-50.8% and -54.9% for 10 and 30 mu g.kg(-1).day(-1), respectively at Day 2). Conclusions: Serelaxin was well tolerated in this study with Japanese AHF patients, with no AEs of concern and favorable beneficial trends on efficacy. These findings support further evaluation of serelaxin 30 mu g.kg(-1).day(-1) in this patient population.