Campath, a Genzyme (GENZ) drug already approved for leukemia, may turn out to be one of the most effective treatments for multiple sclerosis, and it's the first medication to show potential for reversing the disease, according to a study reported Oct. 22 in The New England Journal of Medicine. In a three-year trial involving 334 patients in early stages of the nerve disease, Campath reduced the number of relapses by 74% when compared with Rebif, a form of interferon that's commonly used to treat MS. Campath also lowered the risk of sustained disability by 71% over Rebif, which is co-marketed by EMD Serono and Pfizer (PFE).
The researchers also noted that patients on Campath showed some recovery of lost motor functions and were less disabled after three years than at the beginning of the trial, while those on interferon worsened. Those results, researchers say, suggest Campath may allow damaged nerve tissue to repair, a first for a disease that afflicts about 400,000 people in the U.S. and several million worldwide.
As encouraging as the results may be, Campath can cause very serious side effects, in particular a rare blood condition called immune thrombocytopenic purpura (ITP) that can lead to abnormal bleeding and even death. Six patients on Campath developed ITP during the trial, and one died. Genzyme temporarily stopped the trial after the death and started closely monitoring all patients on Campath for ITP, which can be reversed if treated promptly. The trial was sponsored by Genzyme and Bayer Schering Pharma, which holds marketing rights to Campath.
Despite the danger of ITP, MS specialists welcomed the results. "These outcomes are really pretty remarkable," says Patricia O'Looney, vice-president for biomedical research at the National Multiple Sclerosis Society. "They still have to be confirmed by further trials, but I think it is a very, very promising drug."
Campath is also appealing because it only needs to be administered once a year, intravenously, while Rebif must be given by injection three times a week, O'Looney says. Interferon can also produce severe flu-like symptoms. "There are a lot of patients who cannot tolerate interferon or do not like the shots, so this drug would be an appealing alternative," O'Looney says.
Hope for MS Sufferers
The Campath results provided some rare good news to the MS community. In April, Rituxan, a promising MS drug made by Genentech (DNA) and Biogen-Idec (BIIB), failed in a clinical trial against a particularly tough form of MS. This summer, two more cases of a rare and sometimes deadly brain disorder were reported in patients on Tysabri, an MS drug marketed by Biogen-Idec and Elan (ELN). Sales growth of the drug slowed in the third quarter as a result. Because of reports of a few deaths from the brain disease, Tysabri was taken off the market in 2005, just months after it won Food & Drug Administration approval. The FDA allowed it back on in 2006 on the condition that patients be closely monitored.
Both Tysabri and Campath are antibodies that manipulate the immune system, making it almost a given that serious side effects will arise. But many MS patients are so desperate for better treatments that they are often willing to take risks that would be unacceptable in drugs for less serious diseases.
In cases of MS, an autoimmune disease, the body's immune system attacks myelin, the protective coating around the nerves. The nerves are then destroyed, resulting in physical and mental impairments that can become crippling as the disease progresses.
Further Trials Planned
Campath, first developed at the University of Cambridge in England, works by inhibiting a portion of the immune system that attacks the myelin. Dr. Alasdair Coles of the University of Cambridge, lead investigator of the study, says he was particularly excited by the drug's ability to promote brain repair. "We are witnessing a drug which, if given early enough, might effectively stop the advancement of the disease and also restore lost function," he says. That would be unprecedented, he adds.
Genzyme is now recruiting patients for two additional trials of Campath, and it will likely be three years or so before the company can seek an additional approval for the drug for the treatment of MS.