FDA denies Biogen approval for higher-dose version of Spinraza

The U.S. Food and Drug Administration (FDA) has rejected the approval of a higher-dosage version of Biogen's drug for a rare genetic disorder that causes muscle weakness. The rejection was attributed to necessary updates in the technical section of the application documents. No deficiencies were found in the clinical data demonstrating the efficacy of the high-dose regimen, according to the company. Biogen plans to resubmit the application promptly based on the available information. Spinraza, first approved in 2016 for the treatment of spinal muscular atrophy (SMA), generated global sales of $1.57 billion in 2024, making it Biogen's second best-selling product. Priya Singhal, Head of Development at Biogen, stated that despite the unexpected decision, they remain committed to making the higher-dosage therapy available to individuals with SMA. The rare genetic disorder SMA is caused by mutations in the SMN1 gene and leads to progressive muscle wasting and degeneration of motor neurons. Biogen faces increasing competition from Novartis' gene therapy Zolgensma and Roche's oral medication Evrysdi, both of which have gained popularity due to their ease of administration and broader accessibility. The higher-dosage regimen, already approved in Japan and under review by the European Medicines Agency and other regulatory bodies, comprises two initial doses of 50 mg each 14 days apart, followed by 28 mg maintenance doses every four months. This is compared to the current standard dose of 12 mg. Biogen's application was based on data from clinical studies that showed the higher-dosage version significantly improved motor functions in infants compared to untreated patients. The drug is administered by injection into the spinal fluid to increase protein levels essential for motor neuron survival. Biogen has licensed the global rights for the development, manufacture, and marketing of Spinraza from Ionis Pharmaceuticals.