April 15, 2010 (Toronto) -- Nearly 71% of people with early relapsing-remitting multiple sclerosis (MS) treated with the experimental MS drug alemtuzumab showed no evidence of disease activity four years into a study, researchers report.
That's twice the percentage of patients treated with the approved treatment, Rebif, says researcher Alasdair Coles, PhD, of the University of Cambridge.
Importantly, some of the safety concerns that emerged earlier in the study appear to have been ironed out, Coles tells WebMD.
According to the National MS Society, relapsing-remitting MS accounts for 85% of people who are first diagnosed with MS.
The findings were presented at the annual meeting of the American Academy of Neurology.
Alemtuzumab and MS: Safety Concerns Addressed
Three-year results from the study, reported in 2008, also showed that alemtuzumab outperformed Rebif.
But enthusiasm was tempered by the finding that nearly one in four alemtuzumab-treated patients also developed treatment-related thyroid complications. And 3% of the patients developed a potentially life-threatening autoimmune condition, which resulted in the death of one patient.
Coles says that there have been no new cases of the autoimmune condition, known as immune thrombocytopenic purpura, or ITP. The rate of thyroid problems among patients treated with alemtuzumab is 28%, similar to that in the third-year review, he says.
More importantly, "we answered the big question -- that is, if a patient gets thyroid or ITP, will their MS get worse?" he says.
"It won't. We showed that even if you develop thyroid or ITP, your MS will be treated more effectively with alemtuzumab than with Rebif," Coles says.
An expert not involved with the study urged caution.
The updated results do not "completely alleviate concerns" about the drug's safety, says Aaron Miller MD, director of the Multiple Sclerosis Center at Mt. Sinai Medical Center in New York City and chief medical officer of the National Multiple Sclerosis Society.
"Alemtuzumab is a very promising drug, but this is a phase II trial. Only a phase III trial can really answer the question of a drug's effectiveness and safety," Miller tells WebMD.
Coles says that two phase III trials are under way, with results expected by the end of 2011.
Alemtuzumab vs. Rebif for MS
The phase II trial involved patients with early, relapsing-remitting multiple sclerosis who had not been treated with other MS drugs. A total of 110 patients were treated with standard Rebif and 220 patients were treated with alemtuzumab.
Results of the four-year review showed that about 77% of alemtuzumab-treated patients were relapse-free compared with 49% treated with Rebif.
Among patients who developed an autoimmune problem, the use of alemtuzumab was associated with a 78% reduced risk of relapse, compared with Rebif.
But there is a caveat: "If patients got worse in the first few years, they were eliminated from the study," Coles says.
Alemtuzumab is approved for the treatment of chronic lymphocytic leukemia (CLL). It's thought to work by targeting and destroying certain immune cells that normally protect against infection but are believed to be damaged in MS and other autoimmune diseases, resulting in the destruction of healthy tissue.