Safety, pharmacokinetics, and exploratory efficacy of the oral ghrelin receptor agonist AC01 in heart failure with reduced ejection fraction (GOAL-HF1): a randomised, double-blind, placebo-controlled, phase 1b/2a study

Background: The central problem in heart failure with reduced ejection fraction (HFrEF) is reduced contractility. Existing inotropes are associated with adverse effects. In this exploratory study, we aimed to assess the safety and tolerability of AC01, a novel oral calcium-sensitising inotrope and ghrelin receptor agonist, in patients with HFrEF. Methods: In this phase 1b/2a, randomised, double-blind, placebo-controlled study, adults aged 18-80 years with heart failure for at least 6 months and an ejection fraction of 40% or lower were enrolled at 14 sites in the Netherlands, the UK, Sweden, and Italy. All patients had a transvenous implantable cardioverter defibrillator for primary prevention, with back-up pacing to protect against excessive bradycardia. Other eligibility criteria included sinus rhythm or permanent, persistent, or paroxysmal atrial fibrillation or flutter (only allowed in phase 2a), with a mean resting heart rate of 55-90 beats per min. Randomisation used permuted blocks, with block sizes of four for phase 1b and three for phase 2a. In phase 1b, patients were enrolled in four sequential dose cohorts and randomly assigned 3:1 to ascending doses of AC01 (0·1 mg, 0·3 mg, 1·0 mg, or 3·0 mg) or placebo twice daily for 7 days. In phase 2a, patients were randomly assigned 1:1:1 to parallel groups receiving 1·0 mg AC01, 3·0 mg AC01 (1·0 mg AC01 on days 1 and 2 and 3·0 mg thereafter), or placebo orally twice daily for 28 days. Patients, study personnel, outcomes assessors, those analysing the data, and the sponsor were masked to treatment assignment. The primary outcome was safety and tolerability. Safety was monitored by physical examination, vital signs, safety laboratory assessments, and 12-lead electrocardiograms (ECGs) periodically during the treatment period and until the end-of-study visit (day 12 in phase 1b and day 42 in phase 2a), and cardiac rhythm was continuously monitored remotely using a patch device until day 9 in phase 1b and until day 4 in phase 2a. Adverse or unexpected events, signs, or symptoms were recorded. This study is registered with ClinicalTrials.gov, NCT05642507, and has been completed. Findings: Between Feb 23, 2023, and Aug 28, 2025, 58 patients (53 [91%] male and five [9%] female patients with a median age of 66·0 years [IQR 60·3-72·0]) were randomly assigned: 32 in phase 1b and 26 in phase 2a. In phase 1b, four cohorts of eight patients were enrolled; in each cohort, six patients were allocated to AC01 and two to placebo, with AC01 dose cohorts of 0·1 mg, 0·3 mg, 1·0 mg, and 3·0 mg. In phase 2a, nine patients were allocated to 1·0 mg AC01, eight to 3·0 mg AC01, and nine to placebo. There were 12 AC01-related adverse events in phase 1b and 18 in phase 2a. There were no AC01-related serious adverse events; one treatment-related serious adverse event of increased high-sensitivity cardiac troponin I concentration occurred in a patient receiving placebo in phase 1b. Mild or moderate treatment-emergent adverse events were reported in 33 (80%) of 41 patients receiving AC01 and 12 (71%) of 17 patients receiving placebo. The most common treatment-emergent adverse events were hypotension, non-sustained ventricular tachycardia, dyspnoea, hyperglycaemia, dizziness or vertigo, and headache. ECG data showed no apparent signs of tachycardia, new-onset tachyarrhythmias, myocardial ischaemia, or morphological or conduction abnormalities. No case of symptomatic hypotension was reported, and there were no apparent effects of AC01 on high-sensitivity cardiac troponin I or NT-proBNP. There were no deaths during the study. Interpretation: In patients with HFrEF, AC01 over 28 days appeared safe and well tolerated, and no major harms were identified in this early-phase study. These findings support further investigations of AC01 in larger studies.