This is a randomized, placebo-controlled, double-blind, dose-ranging, multicenter, phase IIb clinical trial to investigate the efficacy and safety of the IMP allo-APZ2-CVU on wound healing in patients with therapy-resistant CVU. The allogeneic IMP allo-APZ2-CVU contains skin-derived ABCB5-positive dermal mesenchymal stromal cells isolated from skin tissue of healthy donors and stored in a donor cell bank.~Patients will be randomized to be treated with allo-APZ2-CVU (dose 1, dose 2, dose 3) or placebo (50 patients per dose group). The patients will undergo treatment with the IMP on Day 0 (V3) and will be followed up for efficacy for 18 weeks (V4 until V14). Two safety follow-up visits will be performed at Month 6 (V15) and Month 10 (V16).~The wound healing process will be documented by standardized photography. The wound size measurement will start at the first Screening Visit (V1) and will be measured at each following on-site visit.~Pain will be assessed using a numerical rating scale and quality of life will be investigated with standardized and validated questionnaires.
The aim of this clinical trial is to investigate the efficacy (by monitoring the wound size reduction of CVUs) and safety (by monitoring adverse events [AEs]) of three dose groups of the investigational medicinal product (IMP) allo-APZ2-CVU, topically administered on target wounds of patients with CVU compared to placebo.