Type 1 Spinal Muscular Atrophy: Risdiplam (RG7916) Pivotal FIREFISH Study Demonstrated Statistically Significant Improvement in Infants

– Study meets primary endpoint in patients living with type 1 SMA

– To date, more than 400 patients have been treated with risdiplam across all studies, with no treatment related safety findings leading to study withdrawal in any risdiplam trial

– Risdiplam PDUFA expected May 24, 2020

SOUTH PLAINFIELD, N.J., January 23, 2020 – PTC Therapeutics, Inc. today announced positive topline results from part 2 of FIREFISH demonstrating that the study met its primary endpoint of proportion of infants who are sitting without support after 12 months of treatment. The pivotal study assessed the efficacy of risdiplam (RG7916) in infants with type 1 spinal muscular atrophy (SMA), the most severe, infantile onset form of this rare and devastating neuromuscular disease. Risdiplam has been well tolerated and no treatment-related safety findings leading to withdrawal have been observed in any risdiplam trial to date. Data from part 2 of the FIREFISH study will be shared with health authorities globally and will be presented at an upcoming medical congress.

“We are excited about the FIREFISH results as they demonstrate how effective risdiplam is in type 1 SMA patients, where developmental milestones such as rolling, sitting and standing were achieved,” said Stuart W. Peltz, Ph.D., Chief Executive Officer of PTC Therapeutics. “These results further support the growing body of evidence of risdiplam’s benefit in SMA patients across all types studied and reinforce the potential of our small molecule splicing platform to identify new therapies for patients who have limited or no treatment options.”

The single-arm part 2 of FIREFISH study assessed the efficacy of risdiplam in 41 infants (eligible age at enrollment between 1 and 7 months) with type 1 SMA treated for 12 months. The primary endpoint in the study was defined as proportion of infants who are sitting without support after 12 months of treatment as assessed by the Bayley gross motor scale of infant and toddler development – third edition (BSID-III). Safety for risdiplam was consistent with its safety profile to date and no new safety signals were identified. No treatment-related safety findings leading to study withdrawal have been observed.

Risdiplam (RG7916), is an investigational, potential first-in-class oral mRNA splicing modifier for the treatment of SMA. FIREFISH is an open-label, two-part pivotal clinical trial in infants with type 1 SMA. Part 1 was a dose-finding study in 21 infants. The primary objectives of part 1 were to evaluate the safety profile of risdiplam in infants and to determine the dose for part 2. Part 1 of the trial showed that infants with type 1 SMA survived and achieved developmental milestones beyond those expected in the natural course of the disease. The SMA program is a collaboration between PTC, the SMA Foundation, and Roche.

Recently, positive results from part 2 of SUNFISH, a study evaluating the efficacy and safety of risdiplam in patients between 2 and 25 years of age with type 2 or 3 SMA, were announced. In November 2019, the U.S. Food and Drug Administration (FDA) accepted a New Drug Application (NDA) and granted Priority Review for risdiplam. The NDA filing was based on 12-month data from the dose-finding part 1 of the pivotal FIREFISH and SUNFISH studies, and preclinical pharmacokinetic and clinical and pharmacodynamic data in all types of SMA. The Prescription Drug User Fee Act (PDUFA) goal date for a decision by FDA is May 24, 2020.