March 30 (Reuters) - The U.S. Food and Drug Administration has approved a higher dose of Biogen's spinal muscular atrophy ⁠drug Spinraza, the company said on Monday, after rejecting it last year.

The approval for a potentially more effective treatment marks a boost for ⁠the U.S. drugmaker battling intensifying competition from therapies such as Roche's oral drug Evrysdi and Novartis' gene therapies Zolgensma ⁠and Itvisma.

Biogen's shares rose nearly 2% in ‌afternoon trade.

The new regimen, which will be available in the U.S. in the coming weeks, uses two 50 milligram initial doses given 14 days apart, followed by a 28 mg maintenance dose every four months, compared to the current standard dose of 12 mg.

Biogen said it will introduce the 28 mg vial ‌at a list price of about $152,000, same as that of the 12 mg vial, ​and the ‌50 mg vial at about $271,000.

Higher-dose Spinraza could address ‌the treatment effect waning-off, which could help penetrate the broader adult population and potentially drive growth from 2026 onwards, said Jefferies ⁠analyst Andrew Tsai.

Spinraza generated global sales of $1.55 billion last ‌year, compared with $1.57 billion in 2024.

The ⁠company is seeing strong interest from ​patients who are currently receiving Spinraza, and, ‌based on early experience in other geographies, from patients who are new to treatment, said Stephanie Fradette, head of the Neuromuscular Development Unit at Biogen.

The high-dose Spinraza is also approved in the European Union, ​Switzerland and Japan.

Spinal muscular atrophy affects nerve cells in the brain ‌and ‌spinal cord that control movement, as well as muscles used for speaking, walking, swallowing, and breathing.

The latest ‌approval was backed by mid-to-late-stage ​trial data that showed the higher-dose version significantly improved motor function in infants compared to untreated patients, with a safety profile similar to the low-dose regimen.

The drug is administered through ⁠an injection into the spinal fluid to boost protein levels essential for motor ‌neuron survival and slow the progression of the disease.

(Reporting by Mariam Sunny and Kunal Das in ​Bengaluru; Editing by Sriraj Kalluvila and Shailesh Kuber)