Aceneuraminic acid is the first approved drug for the treatment of GNE myopathy

To treat an underserved group of patients with a rare disease whose muscles gradually weaken until patients can no longer walk, a team of researchers from across Japan has completed a clinical trial to confirm the safety of long-term administration of a therapeutic drug.

Distal myopathy with marginal vacuoles, or GNE myopathy, is a very rare condition that causes muscle wasting and degeneration in the distal limbs (such as fingers and ankles). Symptoms typically begin between the teens and early 30s and gradually progress to severe loss of motor control. This can significantly impact quality of life as patients slowly lose muscle strength and there are no approved treatment options.

“Although there is demand from patients, developing a treatment to slow the progression of symptoms is difficult due to the rarity of the disease,” notes Masashi Aoki, a professor at Tohoku University. “In the whole of Japan, for example, there are about 400 people with GNE myopathy.”

A treatment for a population of this size is called an “ultra-orphan drug” because it is not profitable for pharmaceutical companies to develop a treatment for such a small group. As a result, these patients are “orphaned” and left without any help.

Despite these hurdles, a team of researchers has developed a treatment. In patients with GNE myopathy, the function of an enzyme that produces sialic acid is impaired. Therefore, patients were given a drug containing aceneuraminic acid (a type of sialic acid) to compensate for this deficiency.

The researchers conducted Phase I and Phase II/III investigator-initiated trials and a proof-of-concept study sponsored by Nobelpharma Co., Ltd. These studies demonstrated the treatment effects of an ultra-orphan drug, “Aceneuraminic acid (Acenobel) sustained-release tablets 500 mg,” in GNE myopathy.

In the current study, 19 patients with GNE myopathy completed a 72-week treatment plan without major side effects. These patients originally participated in a 48-week double-blind treatment trial comparing the drug with a placebo. For this study, treatment was extended to 72 weeks.

The safety and efficacy of the treatment was confirmed in the current study, which was Journal of Neurology, Neurosurgery and Psychiatry. This resulted in Nobelpharma Co., Ltd. receiving official manufacturing and marketing approval from the Japanese Ministry of Health, Labour and Welfare (March 2024). This approval is great news for patients who finally have a safe, viable treatment option.

The research team plans to continue monitoring the effectiveness of the treatment over even longer periods of time.