Pivotal Study for SMA Treatment Begins, Triggers $20M Milestone Payment

Mathew Shanley

The joint development program between PTC Therapeutics, Inc., Roche and the SMA Foundation (SMAF) has transitioned into the pivotal part of the study that will evaluate the safety and efficacy of RG7916 in pediatric and adult patients with Type 2/3 spinal muscular atrophy (SMA).

The 2-part study, named SUNFISH, includes an exploratory dose finding for 12-weeks which has been concluded, and the upcoming confirmatory Part 2 which will take place over 24 months.

SMA, a hereditary disorder, is characterized by a loss of motor neurons in the spinal cord and lower brain stem. Patients progressively lose the ability to walk, eat and breathe because of mutations in the survival motor neuron (SMN1) gene resulting in a deficiency in the spinal motor neuron (SMN) protein. Per CureSMA, it is the top genetic cause of death of infants.

"We are excited to move RG7916 into the pivotal part of the SUNFISH trial," said Stuart W. Peltz, Ph.D., Chief Executive Officer of PTC Therapeutics in today’s press release. "RG7916 resulted in a substantial increase in SMN2 protein production in SMA patients. We believe that a major advantage of RG7916 is that it is an oral drug that distributes throughout the body. This is important because the SMN protein is critical both in the CNS and peripheral tissues."

Part 1 of the study included adolescents and adults (ages 12-25) who received either RG7916 or placebo for 12 weeks to decipher the optimal dose.

Part 2 is a randomized, double-blinded, placebo-controlled study, and its initiation triggers a $20-million milestone payment from Roche to PTC Therapeutics. It will enroll an estimated 168 patients (ages 2-11 years) with either Type 2 or Type 3 SMA for up to 2 years, and will be followed by an open-label extension. Primary outcomes include an evaluation of the safety, tolerability and effectiveness of the drug in comparison to placebo after a year of treatment.

It is the belief of the developers of RG7916 that the therapy has the potential to target the underlying cause of SMA by increasing SMN protein levels in the central nervous system (CNS), muscles and tissues generation of more full-length SMN messenger RNA (mRNA) in SMA patients, via the SMN2 gene.

The joint effort was initiated by PTC Therapeutics and SMAF in 2006 to accelerate development of a potential treatment for the disease. In 2011, Roche purchased the exclusive worldwide license to the PTC/SMA Foundation SMN2 alternative splicing program.

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