- The Food and Drug Administration has extended by three months its review of risdiplam, Roche's closely watched treatment for spinal muscular atrophy, because of the "volume" of data recently submitted by the Swiss pharma, which disclosed the delay Tuesday.
- Roche said the data needing further review includes results from the second part of the SUNFISH study in older patients with less severe SMA. That data came in after the FDA accepted Roche's New Drug Application for risdiplam late last year.
- Risdiplam, which is administered orally, would compete with Novartis' gene therapy Zolgensma and Biogen's Spinraza, both of which are delivered by infusion. Until 2016, when Spinraza was approved, there were no approved treatments for SMA, which is inherited and typically results in death by age two in its most severe form.
The FDA's delay in approving risdiplam is a surprise given the speed with which it has approved rare disease drugs in recent years. Roche explained, though, that the extension is tied to the additional data requested by regulators in February that included full SUNFISH results.
Roche's submission includes data from the most severely affected SMA patients who suffer disease onset in early infancy — so-called Type 1 patients, for whom both Zolgensma and Spinraza are also used. However, the pharma also is seeking approval in older patients who were enrolled in the SUNFISH trial, those with the less severe Types 2 and 3, and ranging in age from two to 25.
In that population group, risdiplam would go up against Biogen's Spinraza directly, since Zolgensma is for now only used in infants below the age of two.
Among older patients, the oral liquid delivery of risdiplam may give it an edge, as Spinraza must be administered through a spinal injection. Zolgensma's trials in these older patients also feature intrathecal delivery.
The newly submitted SUNFISH data is from the second part of the trial, which enrolled patients who have lost the ability to walk. Roche said patients on risdiplam scored significantly better on a test called Motor Function Measure 32 after 12 months than those on placebo, with an average difference of 1.6 points. That test monitors patients' ability to move their heads and limbs, sit, stand and walk.
A second test of upper limb strength and flexibility was also in risdiplam's favor, showing again a 1.6 point difference over placebo.