Biogen Inc reported a better-than-expected quarterly profit as the company cut costs and demand rose for Tecfidera, its key drug for multiple sclerosis (MS).

The company's shares rose 1 percent in premarket trading on Thursday.

Sales of Tecfidera, an oral therapy for patients of the progressive muscle-wasting disorder, jumped 15 percent to $946 million in the first quarter. Biogen gets more than a third of its revenue from the drug.

Expenses fell 6.2 percent after Biogen slashed jobs and stopped developing some drugs to focus on more promising therapies as part of a restructuring plan launched in October.

Selling, general and administrative costs plunged 11.3 percent, while research and development expenses declined 5 percent.

"More impressive... is the lower-than-expected SG&A, which we believe reflects sustainable expense control that could improve go-forward margins," Jefferies analysts wrote in a note.

Biogen's total revenue rose 6.7 percent to $2.73 billion, but missed the average analyst estimate of $2.75 billion, partly due to lower sales of Avonex, another MS drug.

The net income attributable to the company rose 18 percent to $970.9 million, or $4.43 per share, in the quarter ended March 31.

Excluding items, Biogen earned $4.79 per share, beating the average estimate of $4.47, according to Thomson Reuters I/B/E/S.

Biogen's shares were trading at $268.50 before the bell.

Up to Wednesday's close, the stock had fallen more than 13 percent this year.

(Reporting by Amrutha Penumudi in Bengaluru; Editing by Maju Samuel, Shounak Dasgupta and Kirti Pandey)