HP-802247

The objective of this study was to characterize factors associated with closure of venous leg ulcers (VLUs) in a pooled analysis of subjects from three randomized clinical trials.

Closure of VLUs after treatment with HP802-247, an allogeneic living cell therapy consisting of growth-arrested human keratinocytes and fibroblasts, vs standard therapy with compression bandaging was evaluated in three phase 3 clinical trials of similar design. Two trials enrolled subjects with VLUs ranging from 2 cm² to 12 cm² in area with 12-week treatment periods; the third trial enrolled subjects with VLUs between >12 cm² and ≤36 cm² with a 16-week treatment period. The first trial went to completion but failed to demonstrate a benefit to therapy with HP802-247 compared with placebo, and because of this, the remaining trials were terminated before completion. On the basis of no differences in outcomes between groups, subjects from both HP802-247 and control groups were pooled across all three studies. Cox proportional hazards regression analysis was employed to evaluate factors associated with VLU closure.

This analysis included data from 716 subjects with VLU. Factors evaluated for association with healing included age, gender, race, diabetes, glycated hemoglobin level, body mass index, treatment (HP802-247 vs compression alone), and ulcer characteristics including location and area and duration at baseline. In an initial model including all of these putative factors, the following were significant at the P < .10 level: diagnosis of diabetes mellitus, gender, wound location (ankle or leg), baseline wound area, and wound duration at baseline. In a final model including only these factors, all but diabetes mellitus were significant at the P < .05 level. Effect sizes were as follows (hazard ratio [95% confidence interval]): female gender (1.384 [1.134-1.690]), wound location on the leg (1.490 [1.187-1.871]), smaller wound area at baseline (0.907 [0.887-0.927]), and shorter wound duration at baseline (0.971 [0.955-0.987]).

Factors associated with VLU lesions including location, area, and duration were important predictors of healing. Women were more likely than men to achieve wound closure. Factors including body mass index, the presence of diabetes mellitus, and higher concentrations of glycated hemoglobin were not significant independent predictors of wound closure in this analysis.

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.