Amicus ditches skin disorder drug after late-stage failure

CEO John Crowley said the program was "part of the fabric" at Amicus.

A drug for rare skin disease epidermolysis bullosa that Amicus Therapeutics acquired in a $847 million deal two years ago has failed a key phase 3 trial.

The ESSENCE study of SD-101—formerly known as Zorblisa—showed that the topical wound healing agent failed to meet its primary and secondary objectives, and Amicus has now decided to scrap the program. The decision is a massive blow for patients with EB, a group of rare and life-shortening genetic skin conditions that cause the skin to blister and tear at the slightest touch. It currently has no FDA-approved therapies.

SD-101 was being assessed for its ability to treat skin blistering and lesions associated with the disorder, but showed no improvement over placebo in hastening wound closure and increasing the number of patients with closed wounds after three months, the two primary endpoints in the trial.

Amicus' CEO John Crowley (pictured) said at a conference that EB is among the most devastating of rare diseases, and the outcome of ESSENCE is doubly disappointing for patients and their families as it as the largest-ever trial of a therapeutic conducted for EB. A higher-than-expected placebo effect, perhaps due to a higher level of bandaging and wound care, could have confounded the results.

The outcome hasn't come out of left field, as SD-101 failed to hit the mark in a phase 2b trial but showed sufficient activity for the highest dose to be taken forward into phase 3. Shares in the company barely moved on the announcement, suggesting investors were aware this was a high-risk project.

There were glimmers of activity in some patient groups in the 169-patient trial, but not enough to warrant taking the program forward any further, said the company, which at one point suggested the drug could be a blockbuster candidate.

Crowley said the data from the trial will be shared and an open-label extension will continue, but there is no plan to invest further in the product. Amicus acquired SD-101 via the purchase of Scioderm in 2015, stumping up $229 million in stock and cash for the company with another $618 million on offer in milestones. Some $340 million in upcoming milestones will now no longer be forthcoming.

"It's important to note that there are other companies developing treatments for EB," said Crowley, expressing the hope that some of these will benefit patients. "We would rather be the first to fail than the last to try," he added.

According to EB charity DEBRA, other candidates in trials for the disease include Fibrocell Sciences' gene therapy candidate FCX-007, another gene therapy in development at Stanford University, and topical formulations including Berg Health's BPM31510 and Castle Creek's diacerein ointment, among others.

The failure is the latest switchback in a rollercoaster ride for Cranbury, New Jersey-based Amicus, which failed to get its lead drug Galafold (migalastat) for genetic lysosomal storage disease Fabry disease through the FDA in late 2015—having already lost GlaxoSmithKline as a commercial partner in 2013—but managed to claim European approval last year.

The company said in July it is planning to file for Galafold—the first orally active drug for Fabry— in the U.S. before the end of the year, and is also expecting mid-stage data for its Pompe disease candidate ATB200/AT2221 in the third quarter.