Sanofi and its subsidiary Genzyme have announced that the experimental intravenous therapy alemtuzumab (with a proposed brand name Lemtrada,™) met one of two primary endpoints by significantly reducing relapse rates in a two-year study comparing two annual cycles of alemtuzumab against standard subcutaneous dosing of Rebif® (interferon beta-1a, EMD Serono Inc. and Pfizer). The study, called CARE-MS I, involved 581 people with early relapsing-remitting MS. The study did not meet its second primary endpoint of slowing disease progression compared to Rebif. The results were announced in July 11 press release. Data analysis is ongoing and the company expects to provide a full report at an upcoming medical meeting. Another trial of alemtuzumab, called CARE-MS-II, is currently underway.
Background: Multiple sclerosis involves immune system attacks against brain and spinal cord tissues. Alemtuzumab is a humanized monoclonal antibody directed at CD52 (a protein on the surface of immune cells) that is currently approved by the U.S. FDA for the treatment of B-cell chronic lymphocytic leukemia. Its ability to target immune cells led investigators to test its potential as a treatment for relapsing-remitting MS. An earlier phase II study compared two dose levels of alemtuzumab with Rebif in 334 subjects with relapsing-remitting MS who had never taken any other disease-modifying therapies. Those taking alemtuzumab had a 74% reduction in the risk of MS relapse compared with those on Rebif, and a 71% reduction in the risk for sustained accumulation of disability (New England Journal of Medicine 2008 359;17: 30-45).
Dosing was temporarily suspended in the Phase II study due to the occurrence of immune thrombocytopenic purpura (ITP), a rare condition in which low blood platelet counts can lead to abnormal bleeding. After the first cases of ITP occurred, one of which was fatal, Genzyme implemented a patient safety monitoring program which includes patient and physician education and regular contacts with patients. Two phase III studies comparing alemtuzumab with Rebif were then launched.
In June 2010, it was announced that alemtuzumab had been designated by the FDA as a “Fast Track Product.” This designation should expedite its future review by the FDA after the company submits results of the phase III trials. The press release stated that the company expects to file for regulatory approval of alemtuzumab for MS in early 2012.
This Study: In the CARE-MS I study, approximately 581 people with early, active relapsing-remitting MS, who had never received disease-modifying therapy to treat their MS, were randomly assigned to receive alemtuzumab or Rebif. Alemtuzumab was given by intravenous infusion for 5 days initially and for 3 days one year later. Those on Rebif received the standard dose of 3-times weekly subcutaneous injections. According to the press release, after two years the relapse rate of those on alemtuzumab was reduced by 55 percent compared to those on Rebif. After two years, 8 percent of those on alemtuzumab had an increase in their EDSS score (a standard scale of physical disability) compared to 11 percent on Rebif – a difference that was not statistically significant.
According to the press release, the most common adverse event associated with alemtuzumab in the CARE-MS I study included reactions associated with infusions (such as headache, rash, fever, flushing, hives and chills). There were more infections in those taking alemtuzumab, predominantly mild to moderate, and there were no fatal infections. Less than 20 percent on alemtuzumab developed autoimmune thyroid-related problems and less than one percent developed ITP.
In the ongoing CARE-MS II study, approximately 1200 subjects at over 250 study sites have been randomly assigned to receive one of two alemtuzumab treatment regimens, or Rebif.
Comment: These positive results are the first reported from this Phase III study of alemtuzumab. Full details and evaluation of this study, and from another Phase III study now underway, should help define the safety and promise of alemtuzumab as a potential new therapy for relapsing MS.