Biogen Tests Malaria Drug as Cure For Tysabri Brain Infection
A malaria pill developed during the Vietnam War is being tested by Biogen on patients with progressive multifocal leukoencephalopathy, the brain disorder known as PML. Tysabri was pulled from the market in 2005 after three PML cases were reported. It was reintroduced a year later when U.S. regulators said the medications effectiveness, twice that of other MS drugs, outweighed its risks.
In 2008, Tysabri generated $813 million in revenue for Cambridge, Massachusetts-based Biogen and its marketing partner, Elan Corp., of Dublin. The companies also reported five new PML cases since July, reigniting concerns of patients who believe a safer Tysabri would be their best treatment option, said John Richert of the National Multiple Sclerosis Society. Without the risk, sales may more than triple, said Eric Schmidt, a Cowen & Co. analyst in New York, in a telephone interview.
“If they resolved that dangerous situation, I would definitely resume therapy with Tysabri,” said Suzanne Carroll, 53, a Toledo, Ohio, radio-show host who stopped taking the medicine when she developed pneumonia and shingles. Her doctor told her those infections indicated she may be vulnerable to PML, Carroll said.
“I really felt great on the drug,” said Carroll, who produces radio program, “The Jazz Brunch.” “It disappoints me so strongly that Im not able to take it.”
Investor Meeting
Biogen may discuss its Tysabri safety efforts at a meeting tomorrow with investors and analysts to present its latest drug research. The company yesterday rose $1.53, or 3.1 percent, to $51.50 in Nasdaq Stock Market composite trading, after dropping 13 percent in the 12 months before today. Elans shares rose 4.7 percent, or 18 cents, to 4.02 euros in Dublin.
MS, a neurological disease affecting 400,000 Americans, robs people of muscle coordination and balance, sometimes leading to damaged vision and paralysis. The malady is caused when the immune system mistakenly attacks myelin, a protective coating on nerve fibers, disrupting the brains communication with the body.
Tysabri, a laboratory-engineered antibody, is designed to suppress the immune attack that leads to MS.
PML occurs when a common germ, called JC virus, mutates, then evades the bodys immune defenses and penetrates the brain, causing irreversible damage. Researchers theorize that Tysabri may subdue defenses meant to keep the virus out of the brain. The virus breeds in brain cells, destroying them when it replicates.
2,000 Compounds
Biogen has been looking for a PML treatment since 2005, screening about 2,000 compounds known to fight brain infections. The drug showing the most promise in laboratory tests was the commonly used malaria pill mefloquine. A clinical trial is now testing mefloquine in 40 patients with PML from any cause, whether drug-related or from HIV.
“Its been used in thousands of patients for malaria and, if it can help, why wouldnt you use it?” said Al Sandrock, Biogens head of neurology and research, in a telephone interview. “We knew we didnt have time to develop a brand-new drug from scratch, but we thought there might be a drug thats already been approved that might be effective against the virus.
Penetrated the Brain
“We chose mefloquine because we knew it penetrated the brain very well,” he said.
In the trial, patients with PML are given 250 milligram pills of mefloquine for the first three days after they are diagnosed with PML. They then get the drug weekly for as long as six months.
Biogens plan is to develop a PML protocol in which patients are first treated with a blood-cleansing method known as plasma exchange, or PLEX, which takes blood from the body, separates the plasma, and returns the blood to the body. This process washes Tysabri out of patients blood, allowing the immune system to fight the infection. Mefloquine would be given next, before a patient resumes taking Tysabri.
The company has already demonstrated success with PLEX, and the procedure is becoming a standard of care in treating Tysabri PML cases. Its use was added to the drugs prescribing information in October.
Plasma Exchange Findings