FDA Grants Orphan Drug Status to Resolaris as Treatment for Limb Girdle MD

ATyr Pharma’s Resolaris has received orphan drug status in the United States for the treatment of limb girdle muscular dystrophy (LGMD).

The Food and Drug Administration designation gives companies financial and other incentives to develop therapies for diagnosing or treating rare diseases. In the United States that means fewer than 200,000 people.

LGMD covers 20 inherited myopathies, or muscle diseases, with no approved therapy. One of the subtypes is LGMD2B. It is a recessive genetic disease, meaning two mutations — one from each parent — are required for symptoms to appear. A malfunctioning dysferlin gene is what causes the disease.

People with LGMD2B experience progressive debilitating muscle weakness and atrophy, as well as immune cell invasion in skeletal muscle.

ATyr Pharma believes LGMD affects over 16,000 people the United States, 3,000 of whom have LGMD2B.

Resolaris is a first-in-class intravenous protein for treating rare myopathies that have an immune component. ATyr developed it from a naturally occurring protein released by skeletal muscle cells. It could benefit those with LGMD and LGMD2B, the company said.

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“Receiving Orphan Drug Designation for the treatment of all types of LGMD patients with Resolaris is an important step in our overall process of bringing our first Physiocrine-based product candidate to the market to treat patients,” John Mendlein, chief executive officer of aTyr Pharma, said in a press release.

The FDA granted fast track designation to Resolaris in February of this year. That designation allows a company to speed the development of a particularly promising drug intended to treat serious or life-threatening diseases. Resolaris is the first drug candidate for LGMD2B to obtain fast-track status.

American regulators based their fast-track and orphan-drug decisions on results of a Phase 1b and 2 clinical trial (NCT02579239) that assessed the safety, effectiveness and biological activity of Resolaris in 18 patients with LGMD2B and facioscapulohumeral muscular dystrophies.

The trial showed the drug was safe and did not suppress circulating immune cells. It also displayed effectiveness, improving muscle function in 78 percent of treated patients — 7 of 9 people — at 14 weeks. Their scores in a manual muscle test improved by a mean of 6.2 percent compared to baseline, or scores recorded prior to treatment, the company reported at the time.

“We are excited to continue the development of Resolaris to treat patients with rare myopathies with an immune component who currently have limited or no therapeutic treatment options,” Mendlein said.