Biogen Idec

(BIIB) - Get Report

and

Elan

(ELN)

rose Wednesday after the companies late Tuesday received a much-needed boost for their controversial multiple sclerosis drug Tysabri.

After the markets closed Tuesday, the companies said data from a phase III efficacy study showed that treatment with Tysabri led to a significant reduction in disability progression, the rate of clinical relapses, and brain lesions in patients with relapsing forms of multiple sclerosis. The data were presented at the annual American Academy of Neurology meeting in Miami Beach, Fla.

Shares of both companies have slumped since they voluntarily withdrew the drug because of health and safety concerns six weeks ago. On Feb. 28, Biogen and Elan announced that they voluntarily suspended Tysabri from the U.S. market as well as all ongoing clinical trials based on reports of progressive multifocal leukoencephalopathy, or PML, a rare and frequently fatal demyelinating disease of the central nervous system.

Elan shares were up 40 cents, or 10.61%, to $4.17. Biogen shares added 15 cents, or 0.4%, to $36.85.

The companies say their comprehensive safety evaluation concerning Tysabri and any possible link to PML is ongoing. The results of the evaluation will be discussed with regulatory agencies to determine possible re-initiation of dosing in clinical trials and future commercial availability.

The data released yesterday are the two-year results of the Affirm trial, a randomized, efficacy study comparing the drug to a placebo in 942 patients in 99 sites worldwide.

The Food and Drug Administration granted accelerated approval for Tysabri in the treatment of MS in November 2004, based on one-year results from the Affirm trial as well as those of an add-on study known as Sentinel. At the time, the companies agreed to continue testing as a condition of approval.

In the Affirm trial, Tysabri reduced the rate of clinical relapses by 66% after one year, compared with a placebo. In the Sentinel trial of a combined treatment with Tysabri and Avonex, a drug currently on the market, clinical relapses were reduced by 54% compared with the use of Avonex alone.

The Sentinel trial included 1,171 patients taking Avonex and was conducted at 123 trial sites worldwide. In the combination therapy trial, serious infections occurred in 1.3% of patients given a placebo and 2.1% of Tysabri-treated patients. Serious infections included bacterial infections such as pneumonia and urinary tract infection, which responded to antibiotics. Tysabri has been associated with hypersensitivity reactions, including serious systemic reactions, which occurred at an incidence of less than 1% of patients.

Clinical trials were halted and the companies pulled the drug from the market after receiving one confirmed death and one suspected case of patients contracting a rare central nervous system disorder in clinical trials after they had taken Tysabri and another MS drug, Avonex, made by Biogen Idec, for more than 24 months. The second case was later confirmed. Weeks later, a third case of the rare disease, known as PML, was identified in a patient who took Tysabri in a clinical trial for Crohn's disease, a chronic digestive disorder. The patient, who originally had been diagnosed as having brain cancer, died in December 2003.