Health indices were generally flat Monday, but biotech stocks faced turbulence as takeover talk, study results, product problems and regulatory actions sent certain names all over the map.

Investors pumped Biogen Idec ( BIIB) 18.8% to $82.51 Monday after the company announced post-close Friday that third parties -- including famed investor Carl Icahn -- had expressed interest in acquiring the company. Icahn reportedly made a $23 billion bid for the company.

Biogen's Tysabri partner Elan ( ELN) gained ground Monday as well. The company, which has a 50% interest in the MS drug (which is also being reviewed for Crohn's disease), hired Lehman Brothers to advise on its options if Biogen is acquired by a third party. Elan said that under the terms of its agreement, it can acquire for fair value Biogen's 50% economic interest, sell its 50% interest, continue with the existing agreement or restructure the agreement in conjunction with a potential acquisition.

Elan rose $1.82, or 8%, to $24.17. Also, as if there weren't news enough, Biogen and Elan also said Monday that the Food and Drug Administration will take an additional three months to review Tysabri for use as a Crohn's disease treatment.

Speaking of regulatory action, Telik ( TELK) added 48 cents, or 13.9%, to $3.94 after announcing that the FDA lifted a partial hold on Telcyta clinical trials, permitting the company to resume clinical development of the cancer drug.

The FDA halted clinical trials involving Telcyta after Telik disclosed that in the phase III Assist-1 study on women with advanced ovarian cancer, the median survival time for women in the Telcyta arm was 8.5 months, while women in the control arm of the study treated with the approved drugs doxorubicine or topetecan reported a median survival time of 13.6 months.

Telik said at a recent conference that it expected the FDA to lift the hold, following a complete review of Telcyta data. It's developing the drug for ovarian cancer and non-small cell lung cancer.

On the data end, Genzyme ( GENZ) and partner Bayer ( BAY) said Tuesday that top-line three-year data from a midstage clinical trial showed Campath (or alemtuzumab) was more effective than Merck KGaA's Rebif in treatment of multiple sclerosis. The company recently initiated a phase III trial on the drug and if the results are positive, it could file with the FDA around 2011. Also, Bear Stearns analyst Mark Schoenebaum said in a note to Biogen investors that Genzyme could be the industry's next buyout target. Shares added $3.06, or 4.3%, to $74.77.

Telik, Biogen and Genzyme are components of the Nasdaq biotechnology index, which was up a slight 0.1% at 896.67.

Falling at the week's start, Medtronic ( MDT) suspended distribution of its Sprint Fidelis family of leads (wires used with defibrillators) because of the potential for the leads to fracture.

The company said that data indicate the Sprint Fidelis lead viability is trending lower than the company's Sprint Quattro lead at 30 months, and while the difference isn't statistically significant now, it will be over time if the fracture rates remain steady. Shares fell $6.33, or 11.2%, to $50.

Elsewhere, Memory Pharmaceuticals ( MEMY) announced top-line data from its phase IIa study of MEM 1003 for Alzheimer's disease, saying the trial failed to meet its primary endpoint, which was a 12-week mean change in the Alzheimer's disease Assessment Scale -- Cognitive subscale (ADAS-cog) score in the overall population.

The company said that it still believes MEM 1003 warrants investigation because in a subgroup of subjects receiving cholinesterase inhibitors, the change in ADAS-cog favored treatment over placebo -- although the difference wasn't statistically significant. Shares fell 69 cents, or 39.4%, to $1.06.

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