Roche’s hopes of capturing a slice of the spinal muscular atrophy market have been buoyed by phase 3 data showing its risdiplam drug can improve motor function in patients with the muscle-wasting disease.
The results of the SUNFISH study show that after a year’s treatment with risdiplam, patients aged two to 25 with type 2 or 3 SMA had better scores on the Motor Function Measure 32 (MFM-32) scale compared to placebo.
Roche says the data keeps it on course to file for the approval of risdiplam before the end of the year in the US and other world markets, setting up possible approvals in 2020.
If it does get a green light, risdiplam would compete in the market with Biogen’s blockbuster antisense-based SMA medicine Spinraza (nusinersen) as well as Novartis’ recently-approved gene therapy Zolgensma (onasemnogene abeparvovec), which offers a one-shot treatment for the disease.
Both Spinraza and Zolgensma are high-priced drugs – with Biogen’s drug costing $750,000 in the first year and $375,000 thereafter at US wholesale prices, while Zolgensma’s one-time cost is $2.1m.
Spinraza is more established – having been approved in 2017 – and made $1.55bn in sales in the first nine months of the year, while Zolgensma’s made third-quarter sales of $160m, its first full quarter on the market, from use in around 100 infants across all forms of SMA.
Spinraza’s third-quarter showed a dip in sales, but the company insists that isn’t down to Zolgensma competition as Novartis’ drug is currently only approved for patients two years old and younger, which accounts for around 5% of the SMA market.
One issue with Zolgensma is the therapy is less effective in patients who have already been exposed to the virus used to deliver it, which becomes more common with age.
Risdiplam is a closer competitor to Spinraza in terms of its target age range, and could have one advantage in that it is an orally-active treatment, while Spinraza has to be injected into the spine (intrathecally). On the other hand, risdiplam has to be taken every day while Spinraza is dosed every four months after multiple injections in an initial loading period.
Roche is also emphasising the safety of risdiplam, saying that “no treatment related safety findings leading to study withdrawal have been seen in any risdiplam trial to date”.
Last month, a trial of Zolgensma involving the intrathecal injection route for SMA type 2 patients was halted after animal studies pointed to a possible risk with the drug.
Roche has already reported preliminary results of the FIREFISH trial in SMA type 1 and expects to file a rolling marketing application in the US that will update as new results become available. The company is developing the drug in collaboration with the SMA Foundation charity and US biotech PTC Therapeutics.