Roche has presented data from a spinal muscular atrophy (SMA) clinical trial it hopes will support an FDA approval of its challenger to drugs from Biogen and Novartis. The update adds figures to Roche’s earlier top-line readout but leaves questions about the competitiveness of risdiplam unanswered.
Late last year, Roche revealed a clinical trial of risdiplam in 180 patients with type 2 or 3 SMA, the less severe forms of the muscle wasting disease, had met its primary endpoint. Roche used the data to support a filing for FDA approval in all forms of SMA, setting it up to get the green light to sell the drug in the U.S. in May. But the earlier update lacked the data that will shape the asset’s prospects.
Now, Roche has shared data from the trial of the PTC Therapeutics-partnered drug. Roche tracked a 1.55-point difference between the motor function scores of patients in the treatment and control arms, resulting in the trial hitting its primary endpoint with a p-value of 0.0156.
The improvement was driven by the performance of participants aged two to five years old. In that group, 78.1% of subjects experienced a three-point or greater increase on the motor function score as compared to 52.9% of their peers who received placebo. In contrast, more than 40% of patients aged 18 to 25 suffered a worsening of their muscle function scores.
Placebo performed worse still in that older patient group, leading Roche to argue the data show its drug stabilizes disease in a hard-to-treat population. Roche’s case for risdiplam also drew on a key secondary endpoint that tracked a statistically significant improvement in upper limb performance.
With the trial generating safety and tolerability data consistent with earlier studies, Roche may have the results it needs to win FDA approval in the coming months. However, the rapid evolution of the SMA market means that may not be enough to turn risdiplam into a significant product. To do that, Roche will need to persuade patients and physicians to choose risdiplam over rival drugs.
Biogen’s Spinraza and Novartis’ Zolgensma are already available to SMA patients. As an oral therapy, risdiplam may have an edge over Spinraza, which is injected into spinal fluid, in terms of convenience. However, Novartis’ one-shot gene therapy Zolgensma trumps both risdiplam and Spinraza on that front. The harder question of which drug is more effective remains tricky to answer, in large part due to differences between the clinical trial designs.
Shares in PTC fell 6% in premarket trading following the release of the data.