Durability of healing from spray-applied cell therapy with human allogeneic fibroblasts and keratinocytes for the treatment of chronic venous leg ulcers: a 6-month follow-up.

Patients who participated in a Phase 2 trial of HP802-247 for venous leg ulcers were invited to participate in this 24-week follow-up study to assess the durability of healing, document additional ulcer closures, and evaluate posttreatment safety. Consent was given by 90% (206/228), with 80% (183/228) completing all visits. Blinding was retained from the previous trial in which subjects had been randomized to vehicle or one of four cell therapy regimens. Visits were every 8 weeks. Among the 183 subjects, 43% (21/49) previously treated with cells and entering follow-up with an open wound achieved closure, compared with 35% (7/20) previously treated with vehicle, while 10% (11/106) and 17% (3/18), respectively, experienced reopening of a previously closed wound. Subjects previously treated with cells closed more open wounds than those previously treated with vehicle (OR 1.39, 95% CI 0.47-4.10; p = 0.739), and less subjects with a previously closed wound reopened (OR 0.65, CI 0.16-2.60; p = 0.821); however, these findings were not statistically significant. At the final visit, the difference in proportion of subjects with wounds closed continued to favor the best dose from the prior trial (83% closed vs. 58%, delta 25%). Follow-up beyond 12 weeks is necessary to evaluate the full benefit of this therapy, as treatment with cells may provide stimulus toward healing that persists for up to several weeks following the last application. The results show that the greater proportional benefit achieved by HP802-247 relative to standard care after 12 weeks of treatment persists over a meaningful timeframe.