AMPLITUDE-O trial deep-dive: efpeglenatide CV outcomes in T2D (Gerstein 2021 NEJM)

AMPLITUDE-O (Effect of Efpeglenatide on Cardiovascular Outcomes) was a multicenter, double-blind, placebo-controlled, event-driven phase 3 trial sponsored by Sanofi and run at 344 sites across 28 countries. Investigators randomized 4,076 adults with type 2 diabetes and either a history of cardiovascular disease or current kidney disease (eGFR 25.0 to 59.9 mL/min/1.73 m²) plus at least one additional cardiovascular risk factor to weekly subcutaneous efpeglenatide 4 mg, efpeglenatide 6 mg, or volume-matched placebo in a 1:1:1 design, stratified by baseline SGLT2-inhibitor use. The primary endpoint was the first occurrence of a three-point major adverse cardiovascular event composite — nonfatal myocardial infarction, nonfatal stroke, or death from cardiovascular or undetermined causes. Median follow-up was 1.81 years, the shortest of any positive GLP-1 CVOT to date. Results published by Gerstein and colleagues in the New England Journal of Medicine on September 2, 2021 reported a hazard ratio of 0.73 for the primary endpoint — the first positive cardiovascular outcomes trial for an exendin-based, structurally non-human GLP-1 receptor agonist and the validation that the cardioprotective class effect extends beyond the human-GLP-1 backbone shared by liraglutide, dulaglutide, and semaglutide.

Enrollment

4,076

Duration

Median follow-up 1.81 years; trial was event-driven and stopped after the pre-specified MACE accrual was reached

Drug

Efpeglenatide 4 mg and 6 mg (weekly subcutaneous)

Population

Adults with type 2 diabetes and either a history of cardiovascular disease (myocardial infarction, ischemic stroke, unstable angina with electrocardiographic changes, myocardial ischemia on imaging or stress test, or coronary, carotid, or peripheral arterial revascularization) or current kidney disease defined as estimated glomerular filtration rate of 25.0 to 59.9 mL/min/1.73 m² plus at least one additional cardiovascular risk factor. Per the NEJM publication: mean age 64.5 years, 33% female, mean HbA1c 8.9%, mean BMI 32.7 kg/m², mean diabetes duration 15.4 years. 89.6% had established cardiovascular disease at randomization. Background therapy included metformin (74.4%), insulin (61.7%), SGLT2 inhibitors (15.2% — the highest baseline SGLT2 use of any GLP-1 CVOT at that point), and antihypertensives, statins, and antiplatelet agents per standard of care.

Clinical significance

AMPLITUDE-O sits in an unusual position in the GLP-1 evidence base: a fully positive cardiovascular outcomes trial for a drug that was never marketed. The trial answered three questions the rest of the class had left open. First, it showed that an exendin-based GLP-1 receptor agonist — structurally derived from a lizard peptide rather than the human GLP-1 backbone of liraglutide, dulaglutide, and semaglutide — produces a MACE reduction of the same magnitude as the human-backbone agents, removing the molecular-backbone variable as an explanation for the class effect. Second, the trial reported the most explicit dose-response analysis in any GLP-1 CVOT, with the 6 mg arm driving a 35% MACE reduction while the 4 mg arm landed at 18% directional, and a 32% pooled-arm reduction in the kidney composite — evidence that informed the field's later move toward higher-dose semaglutide and tirzepatide. Third, AMPLITUDE-O reached its event target in 1.81 years of median follow-up, the shortest of any positive GLP-1 CVOT, because the cohort was enriched for established cardiovascular disease (89.6%) and concurrent kidney disease — a design choice that shortened the time-to-evidence but also narrowed the generalizability to lower-risk patients. Sanofi nonetheless discontinued efpeglenatide before any regulatory submission, and the drug has not been resurrected by its originator Hanmi Pharmaceutical or any subsequent licensee, leaving AMPLITUDE-O as a load-bearing class-effect paper that is cited far more often than the drug it tested is dispensed.