Biogen Idec’s third-quarter financials have revealed a strong rise in profits and sales of the multiple sclerosis treatment Tysabri.

Net income came in at $278 million, a rise of 34%, while revenues were up 3% to $1.12 billion. Sales were again driven by Tysabri (natalizumab), partnered with Ireland’s Elan Corp, which brought in $207 million, up 21%.

Biogen noted that by the end of the quarter, around 46,200 people were on commercial and clinical Tysabri therapy worldwide, though analysts are a bit concerned about a slowdown in take-up of the drug, especially given its link to the brain infection progressive multifocal leukoencephalopathy.

As for Biogen’s older MS drug Avonex (interferon beta-1a), sales inched up 1% to $580 million, helped by an 8% increase in US revenues. The rheumatoid arthritis and cancer drug Rituxan (rituximab) also did well, and revenues, which come from Biogen's joint venture with Genentech, came in at $284 million.

The company also noted that it is going ahead with a new $1 billion share repurchase programme and confirmed that it has extended its tender offer for Facet Biotech Corp by nearly two months to December 16. Facet has repeatedly rejected the $356 million hostile bid but Biogen says it has no intention of upping its $14.50 per share offer.

The biotechnology giant added that it expects to report full-year revenues in the mid-to-high single digit range, while earnings per share should come in above $2.97.