Clinical Evaluation of a Viable Engineered Skin Tissue* (VEST) for Severe Burns: Post Hoc Cohort Analysis of a Phase 1b Randomized, Controlled Clinical Trial

Introduction/Background: Excision and autografting is the standard of care for many burns. A viable engineered skin tissue* (VEST) is being developed to reduce or eliminate the need for autograft in the treatment of thermal burns, thereby decreasing donor site morbidity.

Methods/Design: To evaluate the safety and efficacy of a VEST,* a clinical trial (NCT01437852) was conducted involving 30 subjects with deep partial-thickness (DPT) burns. Comparable burns on each subject were randomized to receive either VEST* or a control autograft following excision. Subjects were enrolled in three cohorts: Cohorts 1 and 2 (n=10 each) received refrigerated VEST* (≤220 cm² and ≤440 cm², respectively); cohort 3 (n=10) received cryopreserved VEST* (≤440 cm²). Coprimary end points were the percent area of VEST* treatment site that received autograft by 28 days and wound closure by three months.

Results/Findings: In this post hoc analysis of outcomes by cohort, no VEST* treatment sites underwent autografting by Day 28. Mean percent reepithelialization (±SD) at VEST* treatment sites at Day 28 were 83.0% (±28.7) for cohorts 1 and 2 and 98.9% (±3.3) for cohort 3 (p=0.37). Of sites treated with refrigerated or cryopreserved VEST,* 90% (18/20) and 100% (9/9), respectively, were closed by month 3. There was no difference in mean Patient and Observer Scar Assessment Scale (POSAS) total scores between the VEST* and autograft control treatment sites by month 12, irrespective of assessor (clinical observer or subject) or tissue-storage method (refrigeration or cryopreservation.

Conclusions/Implications: A novel VEST* has the potential to promote wound healing in patients with DPT burns without the need for autografting. This post hoc analysis demonstrated that use of VEST,* stored either refrigerated or cryopreserved, results in substantial wound closure without autograft at three months. A phase 3 open-label, controlled, randomized study (NCT03005106) using cryopreserved skin tissue* is ongoing.

*StrataGraft®, Stratatech, a Mallinckrodt Company, Madison, WI.