A chemotherapy drug called Novantrone should become the first government-approved treatment for advanced forms of the disabling neurological disease multiple sclerosis, federal advisers said Friday.
A panel of experts that makes recommendations to the Food and Drug Administration voted that Novantrone, made by biotechnology company Immunex Corp., could safely slow the progress of advanced stages of MS, which can lead to paralysis, vision loss and death.
The FDA usually follows its panels' advice and is expected to decide in the coming months whether to approve Novantrone for MS patients who are experiencing flare-ups of symptoms, such as difficult movement and coordination and blurred vision, and lose function with each episode.
Such stages are harder to treat than the earlier relapsing-remitting MS, in which patients return to nearly normal function during periods of remission. About 350,000 Americans have MS, and about half are in late stages. Panel member Dr. Howard Weiner of Brigham & Woman's Hospital in Boston said doctors already use anti-cancer drugs in MS treatment, but formal FDA approval would "legitimize" the practice and expand Novantrone's use.
"It's an important step in our goal to control and ultimately cure MS," Weiner said. The panel endorsement also was noteworthy for Seattle-based Immunex, best known for its arthritis drug Enbrel and cancer drugs, said chief operating officer Peggy Phillips. Winning FDA support for Novantrone in MS would put the company into a new therapeutic arena and potentially double the drug's annual sales to $100 million, she said.
"It broadens our basic business," Phillips said. According to Immunex's data, a clinical trial of 194 patients, 19 percent who took a placebo suffered a significant loss of ability over six months compared with only 7 percent given the highest dose of Novantrone. Novantrone patients also experienced 69 percent fewer serious relapses than in the placebo group.
Novantrone, known generically as mitoxantrone, has been sold in the United States since 1987 as part of a chemotherapy regimen for attacking leukemia. In cancer treatment, some Novantrone patients suffered congestive heart failure or a decrease in heart function, and panel members considered whether giving such a potent agent was appropriate for MS.
In a clinical trial for MS, Novantrone injections once every three months for two years produced nausea, hair loss and other "manageable" side effects, said Dr. Richard Ghalie, Immunex senior director for clinical development. Serious side effects could be avoided by limiting treatment to two or three years and monitoring patients' hearts closely, Ghalie said.
All but one panel member agreed the drug was safe enough to win approval. With proper precautions, "the likelihood of cardiac toxicity is very low," said Dr. James Grotta of Mackenzie Health Sciences Center in Canada. In patients with MS, the immune system attacks the protective sheath surrounding nerve fibers in the brain and central nervous system, causing scars that interfere with transmission of signals from the brain. Novantrone likely works by reducing the immune system's attack on the nerve coating, Immunex said.
Three drugs already are on the market for early stages of MS, Biogen Inc.'s Avonex, Betaseron by Chiron Corp. and Copaxone by Teva Pharmaceutical Industries . American Home Products Corp. owns a majority stake in Immunex.