Roche has revealed new efficacy data for its spinal muscular atrophy drug risdiplam as it waits for the outcome of a review by the FDA due by 24 May.
The results of a second part of its SUNFISH study showed that risdiplam was able to improve motor function in children and adults with types 2 or 3 SMA – covering an age range from two to 25 – and confirming the efficacy signal seen in the earlier, dose-ranging part of the trial.
SMA is a muscle-wasting disease that affects one in 6,000 to 10,000 live births and is a leading cause of genetic deaths in infants. If approved, risdiplam will be the third drug to treat the disorder, and the first that can be administered orally.
Biogen’s Spinraza (nusinersen) – administered by injection into the spinal column – was the first drug for SMA to reach the market in 2016 and quickly achieved blockbuster status, making $2.1bn last year from its use in children and young adults with all forms of the disease, including the most severe type 1 variant.
It was followed last year by Novartis’ one-shot intravenous gene therapy Zolgensma (onasemnogene abeparvovec) that is approved to treat children with SMA under two, and which has the distinction of being the most expensive drug in the world with a cost of $2.1m.
Zolgensma brought in $361m last year following its approval in May, though its roll-out has been held back by capacity issues that have led Novartis to offer the drug via a lottery-like access programme.
PTC Therapeutics-partnered risdiplam achieved a statistically significant 1.59-point average improvement from baseline on the Motor Function Measure (MFM-32) scale at 12 months, compared with placebo, in SUNFISH part 2, which Roche said “represents a broad, real-world spectrum of people living with SMA.”
The SMN2 splicing modifier had the most benefit in younger children in the two to five age bracket, and in this group78% had a 3-point improvement on the MFM-32 scale, compared to 53% of the placebo group.
Importantly Roche’s drug also seemed to stabilise the disease in older patients in the 18-25 age group, and the company says SUNFISH is the first study to demonstrate that in adults with SMA.
“We are very encouraged by the positive results in this broad group of SMA patients, many of whom are under-served and under-represented in clinical trials,” said Levi Garraway, Roche’s chief medical officer.
The SUNFISH age range means risdiplam will compete most closely with Spinraza if its gets approved, but Roche is also running another trial in younger, type 1 patients – called FIREFISH – that could make it an alternative to Zolgensma.
EvaluatePharma has predicted that risdiplam could become an $800m-plus drug by 2024, and other analysts have said it could make upwards of $2.5bn at its peak.