Health Winners & Losers: ImClone

Buyout fever launched biotech stocks higher Thursday, pushing earnings to the back burner for a day.

The Amex biotechnology index rallied 4.1% to 864.14. The rally got started early when Bristol-Myers Squibb (BMY Quote) announced a $60-a-share bid to buy ImClone(IMCL Quote), valuing the biotech company at $5.2 billion.

Shares of ImClone, a component of the Nasdaq biotech index, soared $17.49, or 37.7%, to $63.93 while Bristol shares gave up 39 cents, or 1.8%, to $63.93.

The buyout enthusiasm spilled over to other stocks as investors pondered the possibility other such Big Pharma-biotech mergers. Amylin (AMLN Quote) and Onyx (ONXX Quote) gained 14.8% and 10%, respectively.

In clinical and regulatory news, Genmab and GlaxoSmithKline(GSK Quote) reported positive preliminary results from a late-stage trial on ofatumumab for patients with chronic lymphocytic leukaemia, or CLL, and said they plan to file for U.S. and European regulatory approval by the end of the year.

If approved, the drug could compete with Genentech(DNA Quote) and Biogen Idec's(BIIB Quote) Rituxan.

Glaxo shares ended essentially flat, while Biogen Idec fell $1.51, or 2%, to $69.76 and Genentech edged up 25 cents, or 0.3%, to $95.25.

A legal and regulatory item, generic-drug maker Barr Pharmaceuticals(BRL Quote) is striking again. The company said it is challenging a patent held by Belgian drug maker UCB Inc. for 5-mg tablets of hay fever treatment Xyzal. UCB filed a patent infringement lawsuit against Barr on Wednesday. The drug was developed by Sepracor (SEPR Quote) and licensed to UCB. Sanofi-Aventis (SNY Quote) markets it in the U.S.