ViroPharma Incorporated has completed enrolment in its pivotal phase II study of maribavir in stem cell transplant patients. This international phase III study is evaluating the efficacy, safety and tolerability of prophylactic use of maribavir administered orally for up to 12 weeks for the prevention of cytomegalovirus (CMV) disease in recipients of allogeneic stem cell transplants (SCT).

The study also will evaluate the pharmacokinetics of maribavir in this subject population. It is being conducted in 90 transplant centres in the US, Canada, and Europe.

"Maribavir may mark the first new advancement in CMV therapeutics for transplant recipients in many years," stated Stephen Villano, MD, vice president, clinical research and development at ViroPharma. "CMV can cause significant and potentially deadly clinical manifestations among transplant recipients, and maribavir represents the opportunity for a shift in CMV treatment paradigm toward prophylaxis against CMV, thus preventing CMV viral infection and disease and allowing for enhanced focus on other aspects of patient outcome following transplantation".

The company also provided the timing of future milestones in the development of maribavir in SCT. These include: Data collection for the 6-month assessments will continue through the end of November 2008; top line phase III clinical data is expected to be announced in the first quarter of 2009; filing of the initial NDA (New Drug Application) in the US, MAA (Marketing Authorization Application) in Europe, and NDS (New Drug Submission) in Canada for maribavir in SCT patients based on the 6-month assessments is expected in the third quarter of 2009. The company will announce the timelines for the ongoing phase III study in liver transplant at a later date, including completion of enrolment and top line data. The company intends to file its supplemental NDA, NDS and MAA variation for this additional opportunity as soon as possible following receipt of initial marketing approvals in SCT.

"These are significant milestones for the development of this important drug, and we are excited by the global interest and support for maribavir among transplant physicians throughout the US, Europe and Canada," commented Vincent Milano, ViroPharma's president and chief executive officer.

CMV is among the most important infectious causes of significant morbidity and mortality in transplant patients. Approximately 60 per cent 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.