Biogen has shared positive top-line results from a phase 2/3 study evaluating a higher dose regimen of its antisense oligonucleotide nusinersen in spinal muscular atrophy (SMA).
The drug is already approved in more than 71 countries under the brand name Spinraza to treat infants, children and adults with the neuromuscular disease.
The company is now investigating a regimen comprising a “more rapid” loading regimen of two 50mg doses two weeks apart and a higher maintenance regimen of 28mg every four months.
Affecting approximately one in every 10,000 babies worldwide, SMA is a severe and progressive genetic disorder characterised by insufficient levels of the survival motor neuron (SMN) protein.
Symptoms vary, but can include weakness of the muscles that control movement, as well as problems with breathing and swallowing.
Administered directly into the central nervous system, nusinersen targets the underlying cause of motor neuron loss by continuously increasing the amount of full-length SMN protein produced in the body.
Part B of the three-part DEVOTE trial randomised treatment-naïve children with infantile-onset SMA to receive the investigational higher dose of nusinersen or the approved 12mg regimen.
The study met its primary endpoint at six months, demonstrating a statistically significant improvement in motor function in patients who received the higher dose regimen compared to those in a matched, untreated control group from the phase 3 ENDEAR study.
The higher dose regimen also demonstrated benefits over the currently approved 12mg regimen on key biomarker and efficacy measures, and was generally well tolerated.
Biogen said it plans to submit regulatory applications for the investigational regimen, which it said could “advance the treatment of SMA”.
Stephanie Fradette, head of the neuromuscular development unit at Biogen, said: “While there has been remarkable progress in the treatment of SMA, there remains significant unmet need. Building on the well-characterised profile of [nusinersen] established over the past ten years, we continue to explore the potential for maximising efficacy outcomes while maintaining our commitment to safety… We look forward to sharing the detailed results with the SMA community and health authorities.”