Apitegromab moves closer to potential FDA approval for kids, adults with SMA
Agency accepts Scholar Rock's resubmission, sets Sept. 30 decision date
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- A decision by the U.S. Food and Drug Administration on whether or not to approve apitegromab, a muscle-strengthening agent for use in SMA, is expected by Sept. 30.
- The regulatory agency has accepted a resubmitted application from developer Scholar Rock, which says it's ready to launch the infusion therapy.
- Clinical trials have demonstrated significant motor function improvements with the therapy's use, especially in younger patients.
The U.S. Food and Drug Administration (FDA) is expected to decide in the coming months whether or not to approve apitegromab, an experimental muscle-strengthening agent designed to improve motor function in people with spinal muscular atrophy (SMA).
Scholar Rock, the company developing apitegromab, resubmitted its application about a month ago seeking the therapy’s approval for children and adults with SMA. The FDA has now accepted that application, with a decision date set for Sept. 30.
“With the FDA’s acceptance of our apitegromab [application], we have achieved another critical milestone as we work with urgency to deliver on our mission to bring the world’s first muscle-targeted treatment to the SMA community,” David L. Hallal, chairman and CEO of Scholar Rock, said in a company press release announcing first-quarter financial results.
This will be the second time the FDA reviews an application seeking approval for apitegromab. The agency previously declined to approve the therapy due to issues at a third-party fill-finish facility — a manufacturing center responsible for the final steps of drug packaging, such as making sure the product is sterile — known as Catalent Indiana.
Scholar Rock has since been working with the facility and the FDA to address those concerns. The regulatory agency has already completed a reinspection of Catalent Indiana for its new review, with feedback expected in the next few months. Scholar Rock has also enlisted a second facility, which is expected to begin manufacturing apitegromab before the agency issues its decision.
Developer is ‘ready to launch’ apitegromab in US
Scholar Rock said it is actively preparing for the commercial launch of apitegromab, so the therapy can be available immediately upon approval, if that’s ultimately granted.
“We are grateful for the FDA’s continued high level of engagement, and we are pleased that important progress continues to be made at both of our fill-finish facilities. Our U.S. commercial team stands ready to launch apitegromab on or at any time prior to the September 30th [expected decision] date,” Hallal said.
Apitegromab is also under review in the European Union, and Scholar Rock said it expects initial feedback from the Committee for Medicinal Products for Human Use, an arm of the European Medicines Agency, this summer. That committee is responsible for providing recommendations on whether or not human medicines should be approved for use in the EU.
The developer said it’s planning to launch apitegromab in Europe in the second half of the year, beginning with Germany.
In SMA, the nerve cells that control movement die off, most commonly due to low levels of the SMN protein. Disease-modifying treatments that boost SMN protein levels can slow disease progression, but many patients continue to experience muscle weakness.
Apitegromab aims to boost muscle strength by blocking myostatin, a protein that normally prevents excess muscle growth. Inhibiting this protein is expected to promote muscle growth and increase muscle strength in people with SMA.
Scholar Rock’s application is based mainly on data from the Phase 3 SAPPHIRE clinical trial (NCT05156320), which tested apitegromab against a placebo in 188 children and young adults. The trial had enrolled participants with SMA type 2 or type 3, ages 2 to 21,who could sit independently.
Treatment was administered as a monthly intravenous, or into-the-vein, infusion for one year, alongside approved SMN-targeted therapies, namely Spinraza (nusinersen) or Evrysdi (risdiplam).
The Phase 3 trial met its primary goal, demonstrating that patients on apitegromab had significant improvements in motor function compared with those on the placebo. Analyses indicated that patients who were younger and who started treatment earlier tended to report the greatest improvements in motor function. No serious side effects related to apitegromab were reported in the study.
Scholar Rock now is running a separate Phase 2 trial, called OPAL (NCT07047144), that is testing apitegromab as an add-on to SMN-targeting therapies in babies and toddlers with SMA younger than 2. The OPAL trial is enrolling participants at about two dozen sites across the U.S. and Europe.
Scholar Rock is also developing a subcutaneous, or under-the-skin, injection version of the experimental therapy, which could be administered at home by patients or caregivers. The company said it plans to communicate with regulatory authorities on this self-administered version once the infusion version is approved.
