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Biogen Secures FDA Nod for Higher Dose of SMA Drug Spinraza

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Key Takeaways

  • Biogen shares rose after the FDA approved a higher-dose Spinraza regimen for SMA treatment.
  • New dosing reduces frequency and shows improved motor function in DEVOTE study patients.
  • Approval may help Biogen counter competition that has pressured Spinraza sales recently.

Shares of Biogen (BIIB - Free Report) rose 2% on Monday after the company announced that the FDA approved a higher dose of its blockbuster spinal muscular atrophy (SMA) drug Spinraza.

The new dosing regimen simplifies administration by offering two initial 50 mg doses spaced 14 days apart, followed by a 28 mg maintenance dose every four months. This approach reduces the dosing frequency compared to the low-dose version, which requires four loading doses of 12mg administered at an interval of 14 days, followed by a 12 mg maintenance dose every four months.

The FDA approval is supported by data from the phase II/III DEVOTE study, which achieved its primary endpoint of statistically significant improvement in motor function in infants with SMA treated with a higher dose of Spinraza. The drug secured approval for a similar indication in the EU in January, based on this data.

Per Biogen, a higher dose regimen of the drug has the potential to slow neurodegeneration faster through greater reductions in neurofilament compared to the low-dose version. Patients who transitioned to the higher dose regimen from the low-dose version experienced improvements in motor function after the move.

Biogen expects to launch the high-dose regimen in the coming weeks.

BIIB Stock Performance

Shares of Biogen have outperformed the industry year to date, as seen in the chart below.

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Spinraza: A Key Revenue Driver for Biogen

The drug was discovered and initially developed by Ionis Pharmaceuticals (IONS - Free Report) . Post approval for the SMA indication, Biogen in-licensed the drug’s worldwide rights from Ionis and assumed responsibility for its future development, manufacturing and commercialization.

Biogen’s Spinraza faces competition from Novartis’ (NVS - Free Report) gene therapy Zolgensma and Roche’s (RHHBY - Free Report) oral drug Evrysdi, both of which are approved for the SMA indication.

Competition from both the NVS and RHHBY therapies has shifted market dynamics, negatively impacting Spinraza’s sales in the United States. Due to increased competitive pressure, sales of the Biogen drug have been declining in the past few years. Spinraza sales declined almost 2% year over year in 2025 to $1.55 billion.

We expect this latest approval of Spinraza to help Biogen address competitive concerns and drive growth in future quarters.

BIIB’s Zacks Rank

Biogen currently carries a Zacks Rank #3 (Hold). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.

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