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Amicus Therapeutics’ Pompe Drug Data Show Improved Muscle Movement

Xconomy New York — 

[Updated 10/5/17, 3:35 pm. See below.] Amicus Therapeutics has its sights set on a second approved drug after reporting that its Pompe disease treatment helped patients reduce the muscle-wasting effects of the genetic disease. The results were from a small, 20-patient study, however, and the Amicus drug will have to pass muster in a larger test, at the least, before regulators consider it for approval.

Amicus CEO John Crowley (pictured above) declined to discuss details of that next step. But after a recent high-profile failure of a drug to treat epidermolysis bullosa, an excruciating and rare skin disorder, it’s likely that the Cranbury, NJ-based Amicus (NASDAQ: FOLD) will try to move aggressively with its Pompe disease treatment, known as ATB200.

The muscle-wasting Pompe disease brings a steady decline in the ability to move arms, walk, and even breathe. Crowley says the new data, presented today at a medical conference in France, are significant because they show improvement on multiple measures, including some patients who were switched from the current standard of care for Pompe patients.

“When you switched them to our drug, it looks like you changed the course of the disease for these patients on these measures,” he says.

Pompe is caused by a genetic defect that leaves patients with a missing or defective enzyme required to break down glycogen, a type of sugar stored in muscle. Without that enzyme, patients experience a progressive weakening of their muscles, including the heart. The disease, which is fatal, affects between 5,000 and 10,000 people worldwide, according to the United Pompe Foundation.

The main approved treatment is alglucosidase alfa (Lumizyme), an enzyme replacement therapy from Sanofi (NYSE: SNY). It is approved in the U.S., Europe, and other markets for Pompe patients of all ages. The Amicus drug is an engineered enzyme that, like the Sanofi drug, is meant to replace the deficient enzyme. But Crowley says that ABT200 is made with additional features: carbohydrate structures on its surface that help the drug move into muscles more effectively. Also, the Amicus drug works with a pill that the patient takes ahead of the infusion. The “chaperone” pill stabilizes the Amicus enzyme, which in turn improves how it is taken up by muscle tissue.

Amicus tested ABT200 in a 20-patient study split into three different groups. The first enrolled patients who could walk. The second consisted of patients who could not walk. Patients in these two groups were switched from alglucosidase alfa to ABT200. The third group enrolled patients who could still walk and had never been treated with an enzyme replacement therapy.

[The story has been updated to clarify the study’s time periods.] According to Amicus, muscle function improved across all groups in 16 of the 18 patients who completed six months of the study. Ten patients had completed nine months of the study; improvement was seen in all 10. Amicus will report nine-month data for all patients at a later date.

In a six-minute walk test used to assess neuromuscular diseases, the mean increase in the five patients who had never taken an enzyme therapy was 42 meters after six months of treatment. At nine months, the mean increase for two patients from the group was 75 meters. In the nine patients who switched from the Sanofi drug to the Amicus drug, the mean increase at six months was 35 meters; at nine months it was 37 meters for eight patients. Patients also showed improvement in tests assessing how much breath they could exhale. Crowley says those results show an improvement upon the standard of care.

Though the study is finished, Amicus has a policy of continuing to give participants medication for the rest of their lives. Crowley says results of an extension study are expected sometime next year. Amicus is also planning a larger study that, if successful, could support FDA approval of the drug. Crowley plans to talk with regulators in the U.S. and Europe about the Pompe drug and offer an update in the first half of next year.

Crowley won’t get into details about what Amicus will discuss with regulators, including the possibility of an accelerated approval based on the limited data so far. But he says Amicus is “committed to finding the fastest way possible to get this drug to patients.”

One Amicus drug is approved. Migalastat has the regulatory nod in Europe to treat Fabry disease, an enzyme deficiency that leads to a buildup of a type of fat in the body. Amicus is preparing to file for FDA approval of that drug after the regulator dropped an earlier requirement for a Phase 3 clinical trial.