Background Many patients with venous leg ulcers do not heal with standard care. HP802-247 is a novel spray-applied cell therapy containing growth-arrested allogeneic neonatal keratinocytes and fi broblasts. We compared diff erent cell concentrations and dosing frequencies of HP802-247 for benefi t and harm when applied to chronic venous leg ulcers. Methods We enrolled adult outpatients from 28 centres in the USA and Canada with up to three ulcers, venous refl ux confi rmed by doppler ultrasonography, and adequate arterial fl ow in this phase 2, double-blind, randomised, placebo-controlled trial if at least one ulcer measured 2-12 cm in area and had persisted for 6-104 weeks. Patients were randomly assigned by computer-generated block randomisation in a 1:1:1:1:1 ratio to 50×10 6 cells per mL every 7 days or every 14 days, or 05×10 6 cells per mL every 7 days or every 14 days, or to vehicle alone every 7 days. All fi ve groups received four-layer compression bandages. The trial sponsor, trial monitors, statisticians, investigators, centre personnel, and patients were masked to treatment allocation. The primary endpoint was mean percentage change in wound area at the end of 12 weeks. Analyses were by intention to treat, excluding one patient who died of unrelated causes before fi rst treatment. This trial is registered with ClinicalTrials.gov NCT00852995. Findings 45 patients were assigned to 50×10 6 cells per mL every 7 days, 44 to 50×10 6 cells per mL every 14 days, 43 to 05×10 6 cells per mL every 7 days, 46 to 05 ×10 6 cells per mL every 14 days, and 50 to vehicle alone. All required visits were completed by 205 patients. The primary outcome analysis showed signifi cantly greater mean reduction in wound area associated with active treatment compared with vehicle (p=00446), with the dose of 05×10 6 cells/mL every 14 days showing the largest improvement compared with vehicle (1598%, 95% CI 556-2641, p=00028). Adverse events were much the same across all groups, with only new skin ulcers and cellulitis occurring in more than 5% of patients. Interpretation Venous leg ulcers can be healed with a spray formulation of allogeneic neonatal keratinocytes and fi broblasts without the need for tissue engineering, at an optimum dose of 05×10 6 cells per mL every 14 days. Funding Healthpoint Biotherapeutics.
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