- Roche on Thursday said its experimental drug risdiplam helped babies with the severest form of the rare disorder spinal muscular atrophy sit unassisted one year after beginning treatment, a finding that should help its case for approval now before the Food and Drug Administration.
- The oral drug was already proved to help older children and adults with a less severe form of the disease from experiencing muscular decline as quickly as patients taking a placebo, helping Roche to make a broad submission to the FDA.
- If approved, risidiplam will enter a hotly contested field already served by two injectable drugs, Biogen's Spinraza and Novartis' gene therapy Zolgensma.
Three and a half years ago, no treatments were approved for spinal muscular atrophy. Now, families of infants diagnosed with the often fatal genetic disorder could soon have three treatments from which to choose.
Spinraza (nusinersen) paved the way in 2016, followed in 2019 by approval for the theoretically once-and-done gene therapy Zolgensma (onasemnogene abeparvovec) in the youngest patients with the severest form of the condition.
Roche and partner PTC Therapeutics are bidding for a broad label from the outset for risdiplam, with an FDA submission last year that included full results from the SUNFISH trial in patients aged two to 25 and from the first part of a study, called FIREFISH, from which a final result was announced Thursday. Since risdiplam received Priority Review from the FDA, the complete data from this trial should enter the submission package.
A decision by the agency is due by May 24.
Roche said it will present findings from both trials at upcoming medical meetings. Detailed data should give physicians a better idea of how the treatment compares to both of its rivals. In the first part of FIREFISH, 41% of patients had achieved the milestone of sitting without assistance, according to a release last year.
If approved, risdiplam could have a unique selling point against Spinraza due to its oral formulation. The Biogen drug must be delivered into cerebrospinal fluid through an injection into the spinal cord, an invasive procedure. Some trials of Zolgensma in older patients have also used this route, although dosing in one trial has been put on hold.
"While we expect risdiplam to achieve the greatest penetration into the older, less severe Type 2/3 population, we believe given its oral convenience, safety profile, and competitive efficacy, meaningful penetration of ~1/3 of the Type 1 population will be achieved," RBC Capital Markets analyst Brian Abrahams wrote in a Jan. 23 note to clients.
Cantor Fitzgerald analyst Alethia Young said the data confirms that risdiplam has the potential to achieve sales of at least $1 billion.
Roche's ambitious program for risdiplam also includes patients who have been previously treated with other therapies, as well as a trial in babies who have been diagnosed through a genetic test but have yet to show symptoms.