EXACT Trial: Results of the Phase 1 Dose-Escalation Study

Abstract

Background: New therapies are needed for patients with refractory angina. Encoberminogene rezmadenovec (XC001), a novel adenoviral-5 vector coding for all 3 major isoforms of VEGF (vascular endothelial growth factor), demonstrated enhanced local angiogenesis in preclinical models; however, the maximal tolerated dose and safety of direct epicardial administration remain unknown.

Methods: In the phase 1 portion of this multicenter, open-label, single-arm, dose-escalation study, patients with refractory angina received increasing doses of encoberminogene rezmadenovec (1×10⁹, 1×10¹⁰, 4×10¹⁰, and 1×10¹¹ viral particles) to evaluate its safety, tolerability, and preliminary efficacy. Patients had class II to IV angina on maximally tolerated medical therapy, demonstrable ischemia on stress testing, and were angina-limited on exercise treadmill testing. Patients underwent minithoracotomy with epicardial delivery of 15 0.1-mL injections of encoberminogene rezmadenovec. The primary outcome was safety via adverse event monitoring over 6 months. Efficacy assessments included difference from baseline to months 3, 6 (primary), and 12 in total exercise duration, myocardial perfusion deficit using positron emission tomography, angina class, angina frequency, and quality of life.

Results: From June 2, 2020 to June 25, 2021, 12 patients were enrolled into 4 dosing cohorts with 1×10¹¹ viral particle as the highest planned dose. Seventeen serious adverse events were reported in 7 patients; none were related to study drug. Six serious adverse events in 4 patients were related to the thoracotomy, 3 non-serious adverse events were possibly related to study drug. The 2 lowest doses did not demonstrate improvements in total exercise duration, myocardial perfusion deficit, or angina frequency; however, there appeared to be improvements in all parameters with the 2 higher doses.

Conclusions: Epicardial delivery of encoberminogene rezmadenovec via minithoracotomy is feasible, and up to 1×10¹¹ viral particle appears well tolerated. A dose response was observed across 4 dosing cohorts in total exercise duration, myocardial perfusion deficit, and angina class. The highest dose (1×10¹¹ viral particle) was carried forward into phase 2.

Registration: URL: https://www.

Clinicaltrials: gov; Unique identifier: NCT04125732.

Keywords: angina pectoris; coronary artery disease; genetic therapy; ischemia; myocardial revascularization; vascular endothelial growth factor.