Updated from 12:09 p.m. EDT

Biogen Idec ( BIIB) is expected to turn in solid first-quarter earnings Thursday, with investors likely to be focused more on performance of the multiple sclerosis drug Tysabri and management comments about merger-and-acquisitions activity than on the company's bottom-line result.

The Cambridge, Mass.-based biotech firm is expected to grow first-quarter earnings by 22% to $1.01 a share on total revenue of $1.08 billion, according to Thomson Reuters.

New patient growth for Tysabri in the first quarter is likely to be the most important data point from Thursday's earnings announcement, with analysts generally expecting little change from the 6% growth rate of new patient additions during the fourth quarter of last year.

On a revenue basis, analysts are looking for worldwide sales of Tysabri of $239 million, a 10% sequential increase. This follows disappointing fourth-quarter sales that were down sequentially and well below analyst estimates. Biogen shares Tysabri revenue with Irish drug maker Elan ( ELN).

Tysabri's performance has been hurt by five cases of patients being diagnosed with progressive multifocal leukoencephalopathy, or PML, a serious brain infection.

Last month, Biogen executives laid out plans to re-accelerate Tysabri patient growth, including new research into treatments that could potentially reverse the effects of PML. The company has also pointed to internal market research showing that a large percentage of neurologists expect to increase use of Tysabri over the next six months while only a small percentage of doctors plan to prescribe less Tysabri.

Biogen CEO Jim Mullen will probably field questions during Thursday's conference call regarding whether the company is a takeover target. This follows market rumors that a large pharmaceutical company might be eyeing Biogen as an acquisition target. The chatter helped drive Biogen shares higher last week.

Biogen management is also engaged in a proxy fight with financier Carl Icahn, who owns 5.4% of the company and is trying to seat his own slate of directors on the company's board. Icahn has stated publicly that he'd like to see Biogen sold.

Biogen is the first of the big-cap biotech companies to report first-quarter earnings. Next week, Gilead Sciences ( GILD) reports on April 21, Genzyme ( GENZ) on April 22 and Amgen ( AMGN) reports on April 23.

Biogen shares were rising 0.1% to $52.99 in recent trading.

At the time of publication, Feuerstein's Biotech Select model portfolio was long Gilead Sciences and Amgen.

Adam Feuerstein writes regularly for TheStreet.com. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.

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