This is a Phase 2, randomized, double-blind, placebo-controlled, multiple dose study to assess the safety, tolerability, and efficacy of JK07 in participants aged 18-85 with heart failure.

There will be 2 cohorts in this study:

Cohort 1: Heart failure (HF) participants with left ventricular ejection fraction (LVEF) of ≤ 40%.

Cohort 2: Heart failure (HF) participants with left ventricular ejection fraction (LVEF) > 40% and ≤ 65%.

Inclusion Criteria:

• Participants with New York Heart Association (NYHA) Class II-III.
• Cohort 1 - Left Ventricular Ejection Fraction (LVEF) ≤ 40%.
• Cohort 2 - Left Ventricular Ejection Fraction (LVEF) >40% and ≤ 65%, elevated N-terminal pro B-type natriuretic peptide (NT-proBNP) ≥ 600pg/mL and atrial fibrillation/flutter.
• Stable heart failure and on optimal medical therapy.
• Screening hemoglobin ≥ 9.0 g/dL.

Exclusion Criteria:

• Uncontrolled hypertension.
• Sustained systolic Blood Pressure (BP) < 90 mmHg and/or diastolic BP < 50 mmHg on 2 consecutive (duplicate seated) readings at screening.
• Heart failure due to hypertrophic cardiomyopathy, restrictive and/or infiltrative cardiomyopathy, arrhythmogenic right ventricular dysplasia, Fabry disease, or Noonan syndrome with LV hypertrophy or a positive serum immunofixation result.
• Diagnosis of stress-induced (Takotsubo) cardiomyopathy, myocarditis, or peripartum cardiomyopathy.
• Diagnosis of chemotherapy- or radiation-induced cardiomyopathy.
• Diagnosed with stroke or Transient Ischemic Attack (TIA) within 12 weeks of screening.
• History of syncope within the last 12 weeks prior to screening or sustained ventricular tachycardia without an implantable cardioverter-defibrillator.
• Moderate or severe aortic and/or mitral valve stenosis.
• Medically documented unstable angina, acute coronary syndrome (e.g., myocardial infarction, troponin-positive with symptoms of angina or unstable angina) within the last 8 weeks prior to start of screening.
• Medically documented ST-elevation myocardial infarction within 12 weeks of screening.
• Any tachycardia (inclusive of Atrial Fibrillation (AF) or atrial flutter) with a resting ventricular rate > 110 beats per minute at screening.
• For participants with a history of AF or atrial flutter, not on adequate anticoagulant therapy via non-vitamin K oral anticoagulants or warfarin if the CHA2DS2-VASc score is ≥ 2 in men or ≥ 3 in women or per local guidelines. Percutaneous occlusion of the left atrial appendage alone is not adequate.
• AF ablation within the last 12 weeks prior to screening or planned during the study duration.
• Symptomatic bradycardia or second (Mobitz Type II)- or third-degree heart block without a pacemaker.
• Cardiac surgery, coronary artery revascularization or indication for coronary artery revascularization, percutaneous coronary intervention, valve repair/replacement or valvuloplasty within 12 weeks prior to screening.
• Implantation of a Cardiac Resynchronization Therapy (CRT) device within 12 weeks prior to screening, or intent to implant a CRT device during the course of the study.
• Previous cardiac transplantation, or any use of mechanical circulatory support or similar device, or implantation expected after randomization.
• Receiving mechanical hemodynamic support or invasive mechanical ventilation within the last 8 weeks prior to screening.
• Receiving Intravenous (IV) inotropes or IV vasopressors within the last 8 weeks prior to screening.
• Receiving IV vasodilators within the last 4 weeks prior to screening.
• Receiving noninvasive mechanical ventilation within the last 4 weeks prior to screening. The use of noninvasive ventilation for sleep disordered breathing is permitted.