Is Acenobel Available for GNE Myopathy Outside Japan?

GNE myopathy is caused by a genetic mutation that prevents the body from producing enough sialic acid, a crucial building block needed for healthy muscle function. Because of this deficiency, researchers have focused on substrate replacement therapies — treatments designed to supply the body with these missing building blocks to slow down muscle weakness.

Acenobel (the brand name for aceneuramic acid, also known as extended-release sialic acid or SA-ER) is one such therapy. However, it is currently only approved for the treatment of GNE myopathy in Japan ^[1]. At this time, it does not have marketing authorization from the US Food and Drug Administration (FDA) or the European Medicines Agency (EMA), meaning it cannot be prescribed through standard pharmacies in the US or Europe ^[1].

Why is Acenobel Only Approved in Japan?

Acenobel received regulatory approval from Japan’s Pharmaceuticals and Medical Devices Agency (PMDA) in March 2024 ^[1]. However, the global regulatory pathway hit a major roadblock. In a large Phase 3 global clinical trial, aceneuramic acid extended-release failed to meet its primary goal ^[2]. The results showed that the drug was not statistically superior to a placebo in improving muscle strength and physical function ^[2].

Because the FDA and EMA generally require strong clinical evidence that a drug provides a significant, measurable clinical benefit compared to a placebo, the failure of this global Phase 3 trial is the primary reason the drug remains unapproved in the US and Europe ^[2].

Can I Get Acenobel Through Compassionate Use or Importation?

Because Acenobel is commercially available in Japan, some patients wonder if they can import it. Depending on your country, there are specific legal pathways for accessing unapproved medications:

• Compassionate Use / Expanded Access: In the US and Europe, these programs sometimes allow patients with serious diseases to access unapproved drugs outside of a clinical trial. However, because the manufacturer must agree to provide the drug and the regulatory agencies must authorize it, securing access to a drug that failed its Phase 3 trial can be highly challenging. You can find official guidelines on the FDA or EMA websites.
• Personal Importation: Some countries allow individuals to import a limited supply of an unapproved medication for personal use under very strict conditions. This usually requires detailed documentation from your treating physician stating that no effective alternative is available domestically, and taking on the full financial cost of the drug out-of-pocket.

If you are interested in exploring these pathways, you will need to partner closely with your neurologist to review your country’s specific “Named Patient” or personal importation regulations.

Other Building Block Therapies in Development

While Acenobel is not broadly available, research into other therapies that replace the missing building blocks is highly active outside of Japan. The most prominent alternative is ManNAc (N-acetyl-D-mannosamine) ^[3]. ManNAc is a precursor, meaning it is a substance the body can easily convert into sialic acid.

ManNAc has been evaluated in clinical trials globally and has demonstrated long-term safety ^[4]. Early studies suggest it successfully improves sialic acid levels in the body and shows preliminary clinical evidence of slowing the loss of muscle strength ^[4][5].

If you live in the US or Europe, participating in an ongoing ManNAc clinical trial might be the most practical way to access a sialic acid-boosting therapy while advancing GNE myopathy research for the entire community. You can search for actively enrolling studies by visiting ClinicalTrials.gov or by connecting with GNE myopathy patient advocacy groups like the Neuromuscular Disease Foundation (NDF).