FDA Grants Rare Pediatric Disease Designation to AMO Pharma for Congenital Myotonic Dystrophy Treatment

Rare Daily Staff

The U.S. Food and Drug Administration granted Rare Pediatric Disease designation to AMO Pharma for AMO-02, its experimental therapy in development for the treatment of congenital myotonic dystrophy.

Congenital myotonic dystrophy is an inherited condition of the muscles that is present at birth. Because myotonic dystrophy is a condition that worsens over time and often does not present until adulthood, a person may not know they have the condition before giving birth to their child. Because it is inherited in an autosomal dominant manner, each child of an affected individual has a 50 percent chance of also inheriting the condition. When myotonic dystrophy is present at birth it is often more severe.

Symptoms may include respiratory problems that improve after the first month of life, low muscle tone (hypotonia), clubfoot, and poor head control and facial weakness. Later in childhood, the symptoms may include lack of concentration, motivation, or energy; delayed motor and intellectual milestones; and delayed bladder and bowel control. There is currently no cure, but treatment and management of the symptoms may help. Though it can be life threatening, babies who survive until their first birthday often live to adulthood. Physical therapy may improve muscle tone and improve the child’s motor development. Motor aids such as canes, crutches, and walkers may also be necessary.

AMO Pharma focuses on the development of therapies for rare childhood onset neurogenetic disorders with limited or no treatment options. AMO-02 is a novel orally available GSK3 beta inhibitor being investigated in a double-blind, placebo controlled, randomized study in children and adolescents with congenital onset myotonic dystrophy intended to support a future submission for marketing authorization. The trial is being conducted at eleven treatment centers globally and plans to enroll a total of 56 patients who will be assessed on a range of measures of CNS features and muscle function associated with congenital myotonic dystrophy.

“This Rare Pediatric Disease designation highlights the significant need for a treatment for congenital myotonic dystrophy and adds additional momentum to our development program,” said Ibraheem Mahmood, CEO of AMO Pharma. “The option of monetizing a PRV voucher also represents a significant opportunity to support our mission to develop novel medicines for children with developmental disorders.”

The FDA grants Rare Pediatric Disease designation for serious or life-threatening diseases with manifestations in individuals aged from birth to 18 years, including access to the FDA’s expedited review and approval process. The designation makes AMO-02 eligible for a Rare Pediatric Disease Priority Review voucher upon approval of the therapy by the FDA.

The vouchers can be used to reduce the time of an FDA new drug approval review to six months from ten months. The vouchers are potentially lucrative because they are transferable. Most recently, Sarepta sold its priority review voucher to Vifor Pharma $111 million in February 2020.

The voucher program was due to expire at the end of September but Congress provided a short-term extension of the program. According to the current statutory sunset provisions, after December 11, 2020, FDA may only award a voucher for an approved rare pediatric disease product application if the sponsor has rare pediatric disease designation for the drug, and that designation was granted by December 11, 2020. After December 11, 2022, FDA may not award any rare pediatric disease priority review vouchers.

Going forward, submitted requests for rare pediatric disease designation will be reviewed in a timely manner but the FDA’s previous 60-day response time no longer applies.

Photo: Ibraheem Mahmood, CEO of AMO Pharma