RecruitingPhase 1Drug trialA Safety and Tolerability Study of HJB647 in Heart Failure Participants With Reduced Ejection FractionThe purpose of this study is to evaluate the safety, tolerability, and pharmacokinetics of HJB647 at two different doses in participants with chronic stable heart failure with reduced or mildly reduced ejection fraction (HFrEF/HFmrEF).