Roche's challenger for SMA market hits goal in phase 3

Roche will share full data from the phase 2/3 trial at an upcoming medical congress. (Roche)

A phase 3 trial of Roche’s risdiplam in patients with type 2 or 3 spinal muscular atrophy (SMA) has met its primary endpoint. The results tee Roche up to file for approval to compete with Biogen and Novartis in the increasingly crowded SMA market.

Roche’s phase 3 clinical trial enrolled patients with less severe forms of the muscle wasting disease. While people with type 1 SMA typically die by the age of two, their counterparts with type 2 and, in particular, type 3 forms of the disease can live long lives. The two less severe forms of SMA are nonetheless associated with mobility problems, respiratory infections and death.

To assess whether risdiplam can help these patients, Roche enrolled 180 people with type 2 or 3 SMA in the second part of a phase 2/3 trial and randomized to receive the SMN2 splicing modifier or placebo orally. 

After one year of treatment, Roche detected a statistically significant change on the MFM-32 motor function scale, resulting in the trial hitting its primary endpoint. Roche plans to share the results with regulators with a view to bringing risdiplam to market in countries including the U.S.

Roche is yet to share data from the second part of the phase 2/3 trial, making it impossible to gauge the chances of it winning approval and the threat it will pose to Biogen’s Spinraza and Novartis’ Zolgensma if it does so. However, the numbers shared from the first part of the phase 2/3 suggest risdiplam could be competitive.

In the smaller, dose-finding part of the study, 58% of participants experienced a three-point or more improvement on MFM-32 after 12 months of treatment. Biogen and Novartis used a different scale in their trials of patients with less severe forms of SMA and enrolled a narrower patient population. That makes comparisons difficult, but the limited evidence suggests risdiplam helps many patients. 

Roche will share full data from the phase 2/3 trial at an upcoming medical congress. The Swiss Big Pharma is also working to generate data from another study that enrolled patients with type 1 SMA.

If the data support a 2020 approval across the three forms of the disease, the SMA community will gain access to its third drug in a little more than three years. Roche will then need to persuade people that risdiplam is a better option than Biogen’s antisense oligonucleotide Spinraza and Novartis’ gene therapy Zolgensma.