Biogen (BIIB) guided for a decline in earnings and revenue for 2025 amid ongoing challenges in its multiple sclerosis product category, despite reporting stronger-than-expected fourth-quarter results.

For 2025, Biogen expects non-GAAP earnings per share between $15.25 and $16.25, implying a decline from 2024's $16.47. It forecasts revenue to decline by a mid-single digit at constant currencies from $9.68 billion last year. The FactSet consensus is for adjusted EPS and revenue of $16.30 and $9.4 billion for the ongoing year.

The sales outlook is expected to reflect further declines in multiple sclerosis product revenue that will likely be partially offset by product launches, the company said. Shares of Biogen fell 4.3% in midday trade.

Biogen's early Alzheimer's Disease treatment LEQEMBI -- that got US regulatory approval in January -- is "uniquely positioned," Priya Singhal, Biogen's head of development, said on a Wednesday call with analysts, according to a FactSet transcript. In a statement, Chief Executive Christopher Viehbacher said LEQEMBI represents "a significant long-term opportunity."

For the fourth quarter, revenue advanced to $2.46 billion from $2.39 billion the year earlier and outperformed the $2.41 billion average analyst estimate on FactSet. Adjusted EPS rose to $3.44 for the three months ended Dec. 31 from $2.95 and beat the Street's $3.33 view.

Multiple sclerosis revenue fell 8% from the same point last year to $1.07 billion. The rare disease segment grew 13% to $535 million, while biosimilars advanced 7% to $202 million.

"Our financial discipline has enabled a restructuring of our operating expenses with a reallocation of resources toward potential future growth drivers," Viehbacher said.

Separately on Wednesday, Biogen and Royalty Pharma (RPRX) announced that the latter will invest up to $250 million to help develop Biogen's late-stage investigational lupus treatment litifilimab. In exchange, Royalty Pharma will receive "mid-single digit royalties on annual worldwide sales," the companies said.