A Safety and Tolerability Study of HJB647 in Heart Failure Participants With Reduced Ejection Fraction

Inclusion Criteria: Participants eligible for inclusion in this study must meet all of the following criteria: * Men and women aged 18 years or older * Stable NYHA functional class II-III * LVEF \<50% * NT-proBNP ≥600 pg/ml if in sinus rhythm or ≥900 pg/ml if in atrial fibrillation at screening * On stable standard of care therapy with sacubitril/valsartan with a dose of at least 49/51 mg BID for at least 4 weeks before screening. Exclusion Criteria: Participants will be deemed ineligible for inclusion if they meet any of the following exclusion criteria: * Acute decompensated heart failure within 3 months prior to screening * SBP \<105 mmHg at screening or baseline. * Acute coronary syndrome, stroke, transient ischemic attack, cardiac, carotid or other major cardiovascular surgery, PCI, or carotid angioplasty within the 6 months prior to screening * Hemodynamically significant mitral and/or aortic valve disease, or any prior valve replacement, except mitral regurgitation secondary to LV dilation at screening * eGFR \<45 ml/min/1.73m2 at screening, as measured by the CKD-EPI formula * BMI \>40 kg/m2 * Strong CYP3A4 inhibitors or inducers, sGC activators (vericiguat), PDE5 inhibitors, and nitroglycerin products * Women of childbearing potential Further eligibility criteria might apply in alignment with the trial protocol.