Developer tries again for EU approval of muscle-strengthening SMA treatment
FDA OK'd infusion therapy, now Isembyld, last month for use in US
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- Scholar Rock has resubmitted an application in the European Union seeking regulatory approval of its muscle-strengthening drug apitegromab.
- The infusion therapy won FDA approval last month and is being launched in the U.S. under the brand name Isembyld.
- Despite promising data from clinical trials, the drug was repeatedly sidelined during the approval process due to manufacturing problems.
After its success in the U.S., Scholar Rock is once again seeking approval in the European Union for its muscle-strengthening drug apitegromab —now launching as Isembyld in America — for spinal muscular atrophy (SMA).
The developer has resubmitted an application to the European Medicines Agency (EMA) for marketing authorization in the EU, but this time has listed a new manufacturing facility for producing the infusion therapy. Problems with a previous plant had derailed Scholar Rock’s original applications for the treatment in both the U.S. and the EU.
The resubmission announcement comes just weeks after apitegromab was approved in the U.S. under the brand name Isembyld. The U.S. approval covers the treatment’s use in people with SMA, ages 2 and older, who are taking medications such as Spinraza (nusinersen) or Evrysdi (risdiplam) that target the SMN2 gene.
“With the launch of Isembyld now underway in the U.S., we are working with urgency to bring this first-ever muscle-targeted therapy to children and adults living with SMA in Europe,” David L. Hallal, chairman and CEO of Scholar Rock, said in a company press release.
Still, no action in the EU is expected until next year, according to the developer.
SMA is primarily caused by mutations that lead to low levels of SMN protein. Lacking this protein, the nerve cells that control movement sicken and die, driving progressive muscle weakness.
In the last decade, several disease-modifying therapies, including Spinraza and Evrysdi, have been approved for treating SMA. These treatments, which work by boosting SMN levels, can slow the disease’s progression and have extended life expectancy and eased symptoms. Still, many SMA patients experience considerable muscle weakness.
Apitegromab resubmission called ‘a decisive step forward’
Apitegromab is an antibody that inhibits the activity of a protein that normally prevents excess muscle growth. In doing so, it essentially aims to take the brakes off of muscle growth, allowing people with SMA to gain more strength and mobility.
Scholar Rock had first sought apitegromab’s approval in the U.S. in 2024. That application was based on data from the Phase 3 SAPPHIRE clinical trial (NCT05156320), which showed that apitegromab as an add-on therapy outperformed a placebo at improving motor function in people with SMA taking Evrysdi or Spinraza.
Despite the positive clinical data, the therapy’s path to approval has been hindered by manufacturing problems. U.S. regulators rejected the company’s initial application due to issues at a fill-finish facility, a type of manufacturing plant that performs the final steps of medication packaging, such as ensuring a product is sterile.
Scholar Rock then worked with the facility, called Catalent Indiana (now fully owned and operated by Novo Nordisk), to address those problems. Earlier this year, the company resubmitted its application in the U.S., and also submitted an application seeking approval in the EU. European regulators had been waiting on a repeat inspection of the Catalent Indiana facility before proceeding with the review.
Still, when U.S. regulators conducted a new inspection earlier this year, the team again found problems at the Catalent Indiana facility. Scholar Rock ultimately changed its U.S. application to remove Catalent Indiana and replace it with a second facility, thereby facilitating U.S. approval.
The resubmitted application in Europe similarly drops the Catalent Indiana facility and replaces it with the same facility that supported the U.S. approval.
“Consistent with our ongoing dialogue with EMA, we are pleased with the expeditious resubmission of our apitegromab [application]. This marks a decisive step forward in advancing our mission to bring apitegromab to the more than 35,000 SMA patients globally who are receiving an SMN-targeted therapy,” Hallal said.
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