Updated from 3:05 p.m. EST

Shares of Elan ( ELN) and Biogen Idec ( BIIB - Get Report) were the worst-performing health-related stocks Monday, after the two companies suspended sales and clinical trials of their multiple sclerosis drug Tysabri because of a patient fatality.

The decision to pull the drug was based on one fatal, confirmed case, and one suspected case of progressive multifocal leukoencephalopathy, which is a rare and often fatal disease of the central nervous system. Both patients, according to the companies, had received more than two years of Tysabri therapy plus the Biogen drug Avonex. Shares of Elan traded down $18.84, or 70%, to $8.06, while shares of Biogen Idec traded down $28.63, or 42.6%, to $38.65.

Oncolytics Biotech ( ONCY) rose 5.7% after the company received Food and Drug Administration clearance to begin a phase I/II trial to investigate the use of Reolysin in patients who suffer from recurrent malignant gliomas. The study's primary objective is to determine the maximum tolerated dosage, dose limiting toxicity and safety profile of Reolysin. The study's secondary objective is to evaluate viral replication, immune response to the virus and any evidence of antitumor activity. Shares traded up 26 cents to $4.83.

Shares of Cell Therapeutics ( CTIC - Get Report) fell 3.2% after the company posted fourth-quarter results that fell below expectations. The biopharmaceutical company posted a fourth-quarter loss of $43.5 million, or 72 cents a share, on sales of $8.13 million. Analysts polled by Thomson First Call were expecting a narrower loss of 54 cents a share on sales of $9.34 million. A year ago the company posted a loss of $36.7 million, or $1.09 a share, on sales of $7.22 million. Shares traded down 33 cents to $9.88.

Bradley Pharmaceuticals ( BDY) fell 26.4% after the company said it is being informally probed by the Securities and Exchange Commission. The probe relates to Bradley's revenue recognition and capitalization of certain payments, the company said. As a result of the inquiry, Bradley said it would delay its 2004 earnings results. The company is cooperating with the SEC and is supplying it with all requested information. Shares traded down $3.50 to $9.75.

Other health care movers included Pfizer ( PFE), down 57 cents to $26.29; Teva Pharmaceutical Industries ( TEVA), up $2.55 to $30.11; Merck ( MRK), down 20 cents to $31.70; Amgen ( AMGN - Get Report), down $1.20 to $61.61; Bristol-Myers Squibb ( BMY - Get Report), up 10 cents to $25.03; Johnson & Johnson ( JNJ), down 62 cents to $65.60; Aastrom Biosciences ( ASTM), down 14 cents to $2.53; Genentech ( DNA), down $1.04 to $47.20; and Schering-Plough ( SGP), down 19 cents to $18.95.