FDA Grants Rare Pediatric Disease Designation to Antisense Therapeutics for DMD Treatment

Rare Daily Staff

The U.S. Food and Drug Administration granted Rare Pediatric Disease designation to Antisense Therapeutics’ ATL1102 for the treatment of Duchenne muscular dystrophy, just ahead of the program’s expiration.

Duchenne muscular dystrophy (DMD) is a rare, fatal neuromuscular genetic disease that occurs in approximately one in every 3,500-5,000 males worldwide. DMD is caused by a change or mutation in the gene that encodes instructions for dystrophin. Symptoms of DMD usually appear in infants and toddlers. Affected children may experience developmental delays such as difficulty in walking, climbing stairs or standing from a sitting position. As the disease progresses, muscle weakness in the lower limbs spreads to the arms, neck and other areas.

Most patients require full-time use of a wheelchair in their early teens, and then progressively lose the ability to independently perform activities of daily living such as using the restroom, bathing and feeding. Eventually, increasing difficulty in breathing due to respiratory muscle dysfunction requires ventilation support, and cardiac dysfunction can lead to heart failure. The condition is universally fatal, and patients usually succumb to the disease in their twenties.

ATL1102 is an antisense inhibitor of CD49d, a subunit of VLA-4 (Very Late Antigen-4). Antisense inhibition of VLA-4 expression has demonstrated activity in a number of animal models of inflammatory disease. The designation was granted based on positive phase 2 results that met the primary and secondary endpoints of safety and efficacy with improvement or stabilization across different measures of motor function and strength.

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 ATL1102 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.

Though the program is due to expire at the end of September, a drug that has been granted RPD designation prior to this date is still eligible to receive the voucher if it receives final FDA approval before September 30, 2022. There is also legislation that has been introduced to extend the program.