AIMS: Harmonized Assessment by Randomized Multicentre Study of OrbusNEich's Combo StEnt (HARMONEE) (NCT02073565) was a randomized pivotal registration trial of the Combo stent, which combined sirolimus and an abluminal bioabsorbable polymer with a novel endoluminal anti-CD34+ antibody coating designed to capture endothelial progenitor cells (EPC) and promote percutaneous coronary intervention (PCI) site healing. METHODS AND RESULTS: Clinically stabilized PCI subjects were randomized 1:1 to receive Combo or everolimus-eluting stents (EES). Between February 2014 and June 2016, 572 subjects with 675 coronary lesions underwent 1-year angiography and fractional flow reserve, with optical coherence tomography (OCT) in the first 140 patients. The primary clinical endpoint was non-inferior 1-year target vessel failure (TVF). The primary mechanistic endpoint of EPC capture activity was superior strut coverage by OCT. Target vessel failure occurred in 7.0% Combo (20/287) vs. 4.2% EES (12/285), a 2.8% [95% confidence interval (95% CI) -1.0%, 6.5%] difference, meeting the non-inferiority hypothesis (P = 0.02). There were no cardiac deaths, with one stent thrombosis observed in the EES group. Quantitative coronary angiography late loss with Combo was equivalent to EES. Optical coherence tomography strut coverage at 1 year was superior with Combo vs. EES [91.3% (95% CI 88.7%, 93.8%) vs. 74.8% (95% CI 70.0%, 79.6%), P < 0.001], with homogeneous tissue in 81.2% vs. 68.8%, respectively. CONCLUSION: Combo stent demonstrated non-inferior 1-year TVF and late loss in a randomized comparison to EES, with superior strut-based tissue coverage by OCT as a surrogate of EPC capture technology activity.