(Reuters) -Biogen beat Wall Street estimates for first-quarter profit on Wednesday as a series of cost-cutting measures helped offset the impact of fierce competition for its older drugs, sending its shares up nearly 4% before the bell.

The company also said its Alzheimer's drug Leqembi, developed with Japanese partner Eisai, recorded global sales of about $19 million, nearly tripling from the fourth quarter of 2023.

The number of patients on Leqembi have increased nearly 2.5 times since the end of 2023, Biogen said.

Biogen and Eisai also intend to increase their sales force as they aim for 100,000 patients by 2026.

Since CEO Christopher Viehbacher took the helm at Biogen in late 2022, the drugmaker has cut jobs, acquired rare disease drugmaker Reata for $6.5 billion and abandoned controversial Alzheimer's drug Aduhelm in an effort to steer the company back to growth.

Biogen is counting on newer drugs to drive growth for the next few years, including a second approved Alzheimer's drug Leqembi, as its multiple sclerosis drugs and its spinal muscular atrophy treatment grapple with increased competition.

Quarterly sales of Biogen's once-blockbuster multiple sclerosis drug Tecfidera, now under pressure from a cheaper generic, came in at $254.3 million, above estimates of $236.84 million.

While the patent for Tecfidera has expired in the United States, Biogen believes it has market protection in Europe until February 2025.

Spinal muscular atrophy drug Spinraza, which is facing stiff competition from rival drugs made by Roche and Novartis, brought in revenue of $341.3 million, missing estimates of $417.79 million for the quarter ended March 31.

Skyclarys, the drug Biogen gained through its Reata acquisition, recorded sales of $78 million, above estimates of $72.3 million.

The company reported an adjusted profit of $3.67 per share for the first quarter, compared with analysts' estimates of $3.45, according to LSEG data.

(Reporting by Sriparna Roy and Vaibhav Sadhamta in Bengaluru; Editing by Devika Syamnath)