Maribavir Markedly Reduced Cytomegalovirus Infection
ViroPharma Incorporated publishes results of its previously described Phase 2 study showing that maribavir, when used as prophylaxis, reduced the rate of cytomegalovirus (CMV) reactivation and was well tolerated when compared to placebo in allogeneic stem cell, or bone marrow, transplant patients. These results were published in the June 1 issue of Blood, the official journal of the American Society of Hematology (ASH) and previously presented in 2006 at the annual ASH meeting in Orlando, Fl.
CMV is among the most important infectious causes of significant morbidity and mortality in transplant patients. Approximately 60 percent of all at-risk allogeneic stem cell (bone marrow) transplant patients will show evidence of CMV infection in the first 100 days post transplant and despite treatment with currently available therapies approximately 10 percent of these patients will progress to develop CMV disease, which may manifest as deadly complications such as pneumonia or gastrointestinal disease. CMV infection is also associated with indirect effects in transplant recipients, including adverse immunologic effects (graft versus host disease (GvHD) after bone marrow transplantation and graft rejection after solid organ transplantation), serious bacterial and fungal infections, and reduced overall survival rates.
In a 111 subject study, maribavir significantly reduced the rate of CMV infection requiring treatment across all dose ranges (15 percent, p=0.001; 30 percent, p=0.051 and 15 percent, p=0.002 in 100 mg BID, 400 mg QD, 400 mg BID doses respectively), compared to placebo (57 percent). No patients taking maribavir at any dose developed CMV disease, compared to the placebo group in which three subjects (11 percent) developed the disease. Moreover, there were no reports of late CMV disease across any treatment groups with a maximum follow up period of five months post-transplant.
"These results are important because they suggest that maribavir has the potential to shift the CMV management strategy in stem cell transplant from pre-emptive therapy to prophylaxis," said Drew J. Winston, M.D., University of California, Los Angeles Medical Center. "It is clear that maribavir has the potential to offer an important new and safer option for clinicians to prevent CMV disease in transplant patients."
Among other observations, GvHD of grade 2 or higher, a common complication in bone marrow transplants, also was found to be less common in the three maribavir treatment arms (14 percent; 29 percent; 23 percent) than in the placebo group (46 percent).
"While this dose-ranging study evaluated the safety and the ability of maribavir to prevent viral reactivation in bone marrow transplant patients, we are particularly encouraged by the possibility that maribavir may help reduce the rate of CMV disease and associated morbidity, something we are investigating in our current Phase 3 study," said Stephen Villano, M.D., vice president, clinical research and development at ViroPharma.