- Patients with spinal muscular atrophy who took Roche and PTC Therapeutics' oral drug risdiplam performed better on motor function than those taking placebo 12 months after beginning treatment, the companies said Monday.
- Participants in the SUNFISH trial were between two and 25 years old and had a less severe form of the disease than those currently treated with Novartis' gene therapy Zolgensma. Novartis recently suspended part of a Zolgensma trial in similar patients because of inflammatory responses observed in an animal study.
- Roche and PTC plan on submitting an application for Food and Drug Administration approval by the end of 2019. If approved on schedule next year, the drug would compete with Zolgensma and Biogen's Spinraza, the first treatment for the degenerative neuromuscular disorder.
Roche said SUNFISH is the largest trial comparing an active treatment to a placebo in the Type 2 or Type 3 forms of SMA. The disorder is caused by a mutation in the SMN1 gene, which helps protect nerve cells vital for movement. Its severity is inversely related to the number of copies a patient has of a second, "back-up" gene called SMN2.
In the U.S., Zolgensma (onasemnogene abeparvovec) is approved to treat infants with just two copies of the SMN2 gene, a group that has the severest form of the condition and dies soonest if untreated. Biogen's Spinraza (nusinersen) has been approved to treat both that and the less severe forms of the disease that affects the patients enrolled in SUNFISH, who generally have three copies of the SMN2 gene.
Roche and PTC did not release data beyond disclosing that patients taking risdiplam scored significantly better on a test called Motor Function Measure 32 after 12 months than those on placebo. That test monitors patients' ability to move their heads and limbs, sit, stand and walk.
The two companies said they plan on presenting SUNFISH data at an upcoming medical meeting. The results also will join an FDA submission, which PTC says will cover the severest patients treated by Zolgensma and the less severe ones that were part of the SUNFISH trial. However, the initial submission will only include data from the first part of SUNFISH, which was primarily intended to find a therapeutic dose.
As an oral drug, risdiplam could have an advantage compared with the intravenous infusion of Zolgensma and the spinal infusion for Spinraza. When treating the same patients as those in SUNFISH, Zolgensma has been delivered via a spinal infusion, and it was that trial that is now subject to a partial FDA hold.
Analysts from Cantor Fitzgerald and RBC Capital Markets wrote Monday that the SUNFISH data support their view the FDA will approve risdiplam and that the drug has high sales potential. Cantor and RBC forecast $3.2 billion and $2.6 billion in potential peak sales, respectively.