Scholar Rock's experimental SMA therapy nabs speedy review voucher

The FDA has handed Scholar Rock a rare pediatric disease designation voucher, which can allow the biotech a speedy review of its leading of spinal muscular atrophy (SMA) hopeful SRK-015.

The drug targets the progressive, rare genetic disease that leads to motor function impairments in young children. For decades there were no treatments, but there are now three, all coming in the past few years.

The latest, Roche’s Evrysdi, a survival motor neuron-2 splicing modifier, was approved in the past week, and allows patients to take the drug at home. The other two drugs are Biogen’s Spinraza, an antisense oligonucleotide, and Novartis’ gene therapy Zolgensma.

Those companies have been battling for market share and working to grow sales, as Spinraza sales reached $2.1 billion last year, while Zolgensma generated $361 million during its launch year.

Scholar Rock’s SRK-015 works as a selective inhibitor of the activation of myostatin, and say its drug “may promote a clinically meaningful increase in muscle strength.” It’s a similar theory behind research in another devastating childhood disease, Duchenne Muscular Dystrophy (DMD), although both Roche and Pfizer have in the past tried and failed in this approach.

The biotech will hope to have better luck in SMA, and says it is “on track” report six-month interim efficacy and safety data from the ongoing TOPAZ phase 2 clinical trial of its med, in patients with Type 2 and Type 3 SMA, in the fourth quarter. Top-line data for the 12-month treatment period are expected in the first half of 2021.

There are four main types of SMA, with Type 2 affecting older babies and toddlers, with symptoms less severe than Type 1. Type 2 SMA can shorten life expectancy, but most children with it survive into adulthood.

Type 3 meanwhile usually develop symptoms after 18 months of age, but this is very variable and sometimes it may not appear until late childhood or early adulthood. It doesn’t impact life expectancy.

Now, the Scholar Rock has that rare pediatric disease designation for its rare drug. Under this program, a biopharma that gains approval for a rare pediatric disease can grab a voucher that can be redeemed to receive a priority review of a new, separate marketing application for a different drug.

Recently, these have become hot property and sold off for $100 million-plus to another buyer, given the seller a quick cash grab and the buyer a potentially quicker approval.

We’ll have to wait and see whether the biotech decides to hold on to the voucher for its other programs, many of which are partnered with an array of biopharmas.