FDA OKs Stronger Spinraza for Spinal Muscular Atrophy

The U.S. Food and Drug Administration has granted approval for a higher dosage of Biogen's spinal muscular atrophy (SMA) drug, Spinraza. This decision comes after the regulatory body initially rejected the application last year, requesting revisions.

The newly approved regimen involves two initial 50 milligram doses administered 14 days apart, followed by a 28 milligram maintenance dose every four months. This contrasts with the current standard 12 mg dose.

Biogen's shares saw an increase of 2.3% in early trading following the announcement. The company plans to introduce the 28 mg vial at the same price as the 12 mg vial.

Analysts suggest that the higher-dose Spinraza could help combat the waning-off effect observed with a more rapid loading dose. This enhanced treatment is expected to better target the adult population and potentially drive growth from 2026 onwards.

Spinraza generated global sales of $1.55 billion last year, a slight decrease from $1.57 billion in 2024. The drug works by boosting protein levels essential for motor neuron survival through injections into the spinal fluid.

Data from mid-to-late-stage trials supported Biogen's application, demonstrating that the higher-dose Spinraza significantly improved motor function in infants compared to those untreated. The safety profile of this higher dose was found to be similar to the lower-dose regimen.

Spinal muscular atrophy is a condition affecting nerve cells that control movement, impacting functions such as speaking, walking, swallowing, and breathing. The approval of the higher-dose Spinraza offers a potentially more effective treatment option for patients battling this debilitating disease, amidst increasing competition from other therapies.