Biogen Inc raised its full-year profit and revenue forecasts on Wednesday, while reporting a big miss on quarterly sales of its Alzheimer's disease drug as its use stalls amid uncertainty of insurer coverage.

The forecast assumes minimal revenue from the treatment, Aduhelm, this year, the company said, with a ramp-up expected once there is clarity on reimbursement from Medicare, the U.S. government health plan for people aged 65 and older.

Biogen recorded $300,000 in sales of the $56,000-a-year treatment, well short of analysts' average estimate of $10.79 million, according to Refinitiv data.

The drugmaker has pinned its hopes on Aduhelm, the first new treatment for the memory-robbing disease in nearly 20 years, as it wrestles with increased competition for its main revenue drivers.

However, the uptake has been slower than expected as several commercial insurers wait for further direction from the U.S. Centers for Medicare & Medicaid Services (CMS) before covering the drug and some large hospitals have declined to use it amid controversy over its approval. 

The CMS will give its initial opinion on whether it will cover Aduhelm's cost in January 2022, with a final decision expected in April.

Biogen raised its revenue forecast to $10.8 billion to $10.9 billion from $10.65 billion to $10.85 billion earlier, betting on demand for its multiple sclerosis drugs and biosimilars.

It also increased adjusted earnings per share expectations to $18.85 to $19.35, from $17.50 to $19.00.

The company's shares rose 2% to $274.50 in trading before the bell.

Multiple sclerosis drug Tecfidera brought in sales of $498.6 million in the third quarter, beating estimates of $408.16 million.

Excluding items, Biogen earned $4.77 per share, compared with Refinitiv IBES estimates of $4.09.

(Reporting by Oishee Majumdar and Dania Nadeem in Bengaluru; Editing by Sriraj Kalluvila) ((oishee.majumdar@thomsonreuters.com;))