May 1 (Reuters) - Biogen beat first-quarter

profit and revenue expectations on Thursday, as strong demand

for its rare disease drugs helped offset declining sales of its

multiple sclerosis drugs.

The drugmaker has been counting on newer launches such as

genetic disorder drug Skyclarys as demand falls for its once

top-selling multiple sclerosis medicines in the face of stiff

competition in a crowded treatment market.

CEO Christopher Viehbacher, who took the helm in 2022, has

focused on deals, cost-cutting measures and newer drugs to

address investor pressure for growth.

The company has been doubling down on its Alzheimer's drug

Leqembi, but it has failed to live up to lofty expectations due

to concerns over cost, efficacy and side effects. It sells for

$26,500 annually in the U.S.

The company said it does not expect any material impact from

President Trump's sweeping tariffs implemented to date. Biogen

said about 75% of its U.S. revenue last year came from products

manufactured in the country, which includes Leqembi and spinal

muscular atrophy treatment Spinraza.

Biogen expects 2025 profit per share of $14.50 to $15.50,

compared with its previous forecast of $15.25 to $16.25.

It reported an adjusted profit of $3.02 per share for

the quarter, compared with analysts' expectations of $2.52 per

share, according to estimates compiled by LSEG.

U.S. sales of Leqembi, which the company sells with Japan's

Eisai ( ESALF ), were $52 million for the first quarter ended

March 31. The Wall Street consensus estimate was at $54 million,

according to brokerage Jefferies.

Sales of multiple sclerosis drugs such as Tecfidera fell 11%

to $953 million.

Sales of rare disease drugs, including Skyclarys and

Spinraza, rose 33% to $563 million in the quarter.

Revenue rose 6% to $2.43 billion, and came above analysts'

average estimate of $2.23 billion.

(Reporting by Christy Santhosh and Mariam Sunny in Bengaluru;

Editing by Devika Syamnath)