Scholar Rock to resubmit application for SMA therapy apitegromab to FDA
Submission contingent on successful reinspection of manufacturing site
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- Apitegromab, a muscle-strengthening therapy for SMA, is being resubmitted for FDA approval.
- Approval hinges on a successful FDA reinspection of a manufacturing facility, not safety or efficacy concerns.
- The therapy is an add-on for SMA types 2/3 patients already on SMN-boosting treatments.
Scholar Rock plans to resubmit its application to the U.S. Food and Drug Administration (FDA) seeking approval for apitegromab, an investigational muscle-strengthening therapy for spinal muscular atrophy (SMA).
The submission is contingent on the successful FDA reinspection of a manufacturing site operated by the company’s third-party fill-finish facility, Catalent Indiana, which is part of Novo Nordisk, the developer stated in a company press release. Catalent is tasked with the final packaging steps for the drug, ensuring the product is sterilized.
Last year, the FDA rejected the company’s initial application for apitegromab, citing manufacturing issues identified during a routine general inspection of the site. The agency didn’t express concerns for the therapy’s safety or efficacy.
Scholar Rock’s efforts to resubmit the application began with a “constructive and collaborative in-person meeting” with the FDA late last year, which included representatives from Cure SMA and Catalent.
Earlier this year, the agency met with representatives of Catalent’s Indiana facility to discuss Novo Nordisk’s progress in addressing the site’s issues. At that time, the FDA did not request any additional corrective actions related to remediation efforts at the facility.
If approved, a U.S. launch of apitegromab is expected by the end of this year, according to Scholar Rock.
“We are encouraged by the FDA’s continued engagement and shared sense of urgency as Novo Nordisk works expeditiously to remediate its Catalent Indiana facility,” said David L. Hallal, chairman and CEO of Scholar Rock. “We are ready to resubmit our apitegromab [application] following successful reinspection of the site by the FDA.”
To help ensure a consistent supply, the company is also advancing work at a second U.S.-based fill-finish manufacturing facility. Technology transfer and engineering runs are underway, with additional manufacturing runs planned for this year. Scholar Rock expects to submit a supplemental application later this year to add this facility to its manufacturing network.
Meanwhile, the review of apitegromab’s marketing application in Europe is ongoing, with a decision expected by June of this year. Scholar Rock is preparing for a potential European launch in the second half of this year, starting in Germany, while continuing disease education and engagement efforts with healthcare providers and advocacy groups.
Apitegromab blocks protein that normally limits muscle growth
SMA is chiefly caused by genetic mutations that result in reduced levels of SMN, a protein essential for the health of motor neurons, the specialized nerve cells that control muscle movement. When SMN levels are too low, motor neurons gradually become damaged and die, leading to hallmark symptoms of muscle weakness and wasting.
Several currently available treatments increase SMN protein levels, significantly improving outcomes for many people with SMA and slowing disease progression. Despite these benefits, many patients continue to experience muscle weakness.
Apitegromab was developed as an add-on therapy for SMA patients who are already receiving SMN-boosting treatments. It targets muscle directly by blocking myostatin, a protein that normally limits muscle growth. By reducing myostatin activity, apitegromab aims to help improve muscle strength and function in people living with SMA.
Scholar Rock’s applications for apitegromab approval were supported by results from the Phase 3 SAPPHIRE clinical trial (NCT05156320). The study enrolled more than 180 children and young adults, ages 2-21, with SMA type 2 or type 3. All participants were already receiving approved SMN-targeting treatments, either Spinraza (nusinersen) or Evrysdi (risdiplam).
The study met its primary goal, showing that patients who received apitegromab, administered by infusion into the bloodstream, had significantly greater improvements on a standardized measure of motor function than those who received a placebo. No serious side effects related to apitegromab were reported during the study.
Our highest priority is to serve children and adults living with SMA by bringing apitegromab through the regulatory review process as quickly as possible.
Apitegromab is also being tested in infants and toddlers with SMA, up to age 2, in the Phase 2 OPAL clinical trial (NCT07047144). To be eligible, participants must have received an approved SMN1-targeted gene therapy or be continuing treatment with an approved SMN2-targeted therapy. Enrollment and dosing are ongoing at sites in the U.S. and Europe.
To make treatment more convenient, Scholar Rock is developing a subcutaneous (under-the-skin) version of apitegromab, designed for patients or caregivers to administer as a small-volume injection, potentially using an autoinjector. A Phase 1 study in healthy volunteers has been completed, and further development is underway, including planned discussions with U.S. and European regulators.
In preparation for a potential approval, Scholar Rock is expanding its U.S. commercial team and strengthening relationships with SMA treatment centers and insurers. The company says its outreach efforts focus on raising awareness of the importance of targeting the full motor unit — both the motor neuron and the muscle — in treating SMA.
“Our highest priority is to serve children and adults living with SMA by bringing apitegromab through the regulatory review process as quickly as possible,” Hallal said.
