Amicus Therapeutics said today it is halting development of its novel topical wound-healing agent SD-101 after the drug candidate failed a Phase III trial assessing its efficacy and safety in patients with epidermolysis bullosa (EB), an inherited fragile skin disease.

SD-101 missed its primary and secondary endpoints in the Phase III ESSENCE (SD-005) trial. No statistically significant difference between patients treated with SD-101 and placebo was seen in either of the study’s primary endpoints—time to target wound closure within 3 months and percentage of patients achieving target wound closure by month 3.

Amicus disclosed topline results for the second primary endpoint, with the percentage of patients achieving target wound closure by month 3 reaching 49% of SD-101 patients and 54% of patients treated with placebo.

“We are disappointed that this Phase 3 study of SD-101 did not meet the primary endpoints in EB,” Amicus chairman and CEO John F. Crowley said in a statement. “In keeping with our Amicus mission, we have a strong commitment to the EB community and will work closely with investigators and other leading experts to understand and to share these data.”

However, Amicus said it has “no current plans” to invest in any additional clinical studies or commercial preparation activities for SD-101. The company said it will further analyze data from the ESSENCE trial with key stakeholders in the EB community, including physicians, patient organizations, and regulators.

While that occurs, Amicus said, patients in two ongoing extension studies related to SD-101, SD-004 and SD-006, will have the opportunity to continue being treated with the drug in consultation with their physicians.

ESSENCE was a randomized, multicenter, double-blind, placebo-controlled study assessing SD-101 in patients with documented diagnosis of simplex, recessive dystrophic, or junctional non-Herlitz EB. Target wounds of participants were required to be chronic (at least 21 days old) and between 10 and 50 cm2 in size. 

A total 169 patients were randomized to SD-101 treatment (n=82) or placebo (n=87) for a three-month primary treatment period, followed by the ongoing SD-006 open-label extension study, in which all patients were treated with SD-101.

Amicus inherited SD-101 when it acquired Scioderm in 2015 for up-to-$847 million. The deal price consisted of $229 million in cash and stock upfront; up to an additional $361 million to Scioderm shareholders in cash or stock upon achievement of clinical and regulatory milestones; and $257 million to Scioderm shareholders in cash or stock upon achievement of certain sales milestones.

Amicus’ lead drug remains its Fabry disease treatment migalastat, for which the company has won approval in the European Union, where it is marketed as Galafold™. In the U.S., Amicus plans to submit a new New Drug Application (NDA) by year’s end after the FDA, in an unusual about-face, reversed a decision made last year to require an additional Phase III study assessing migalastat in gastrointestinal symptoms.

As for SD-101, Amicus added that it saw “encouraging trends” from ESSENCE in wound closure in unspecified subpopulations, and that treatment-emergent adverse events (TEAEs) were similar across both the SD-101 and placebo cohorts. The most common TEAEs were nasopharyngitis, pruritis, and pyrexia, Amicus said.

“In seeking to develop novel, high-quality therapies for those living with devastating rare diseases, we may sometimes fail,” Crowley added. “But we would rather be the first to fail, than the last to try.”

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