Redasemtide Shows DEB Ulcer Closure, Misses Stroke Endpoint

Shionogi reported contrasting Phase 2 results for redasemtide, an HMGB1-derived regenerative medicine candidate. The therapy closed refractory ulcers in three of four patients with dystrophic epidermolysis bullosa, while a global Phase 2b trial in acute ischemic stroke failed to show a statistically significant improvement in 90-day disability versus placebo.

Regenerative Approach Targets Tissue Repair

Redasemtide (S-005151) is a peptide derived from high-mobility group box 1 (HMGB1), a nuclear protein involved in recruiting mesenchymal stem cells to sites of tissue injury. Rather than administering living cells, the candidate is intended to stimulate endogenous regenerative processes through pharmacologic treatment.

The approach is being evaluated across several conditions involving tissue damage, including dystrophic epidermolysis bullosa (DEB), acute ischemic stroke, chronic liver disease, osteoarthritis, and cardiomyopathy.

DEB is a rare inherited disorder in which defects in structural proteins that anchor the epidermis to the dermis make the skin highly vulnerable to blistering and ulceration. Severe disease can lead to scarring, digital fusion, esophageal strictures, anemia, and increased risk of squamous cell carcinoma, while fundamental treatment options remain limited.

Ulcer Closure Achieved in Three of Four DEB Patients

In an additional Phase 2 trial in patients with DEB, the primary endpoint of closure of refractory ulcers was achieved in three of four patients. Some patients also showed improvement in clinical measures, including total body ulcer area.

The small patient population limits the ability to draw firm conclusions about efficacy, but the ulcer-closure findings provide a clinical signal in a disease where persistent wounds represent a major therapeutic challenge.

Shionogi reported no new safety concerns and said redasemtide was well tolerated in the study.

Global Stroke Trial Misses Primary Endpoint

The results were less favorable in acute ischemic stroke. The global Phase 2b study evaluated redasemtide against placebo in patients treated within 25 hours of stroke onset.

Among patients who did not undergo endovascular recanalization therapy, the primary endpoint was the modified Rankin Scale (mRS) score at 90 days after treatment initiation. The scale measures disability and dependence in daily activities following neurological injury.

Redasemtide did not produce a statistically significant improvement in 90-day mRS compared with placebo, meaning the trial failed to meet its primary endpoint.

However, investigators observed a trend toward better mRS outcomes with redasemtide, consistent with an earlier Japanese Phase 2 study. An exploratory subgroup analysis also suggested a potential benefit among patients with more severe strokes who had not undergone endovascular recanalization.

Safety remained favorable, with adverse-event rates comparable between the redasemtide and placebo groups and no new safety concerns identified.

Development Strategy Now Diverges by Indication

The contrasting results will shape redasemtide’s next development steps. For DEB, Shionogi plans to continue discussions with StemRIM and other relevant parties while evaluating the future development strategy, with the goal of advancing the candidate toward patients with limited treatment options.

For acute ischemic stroke, the company will conduct a detailed analysis of the Phase 2b results before determining its next development strategy.

The findings therefore leave redasemtide with a potentially meaningful regenerative signal in DEB, while its stroke program faces a more uncertain path after failure of its prespecified primary endpoint.

Reference

StemRIM and Shionogi Announce Topline Results of Clinical Trials of Redasemtide in Patients with Dystrophic Epidermolysis Bullosa and Acute Ischemic Stroke, 09 September 2026