EXTON, Pa., July 27, 2004 (PRIMEZONE) -- ViroPharma Incorporated (Nasdaq:VPHM) today announced the initiation of its Phase 2 clinical program for maribavir, an oral antiviral drug that inhibits cytomegalovirus (CMV), in allogeneic bone marrow (stem cell) transplant patients. Preliminary data from the Phase 1 maribavir program presented recently at the Company's pre-Phase 2 clinical investigator's meeting showed a favorable safety and pharmacokinetic profile for maribavir.
"Although there are products currently available to treat CMV infection, their use is limited due to potential toxicities. Our hope is to develop this promising agent into a leading anti-CMV drug by providing transplant patients an effective option with an improved safety profile," commented Colin Broom, M.D., ViroPharma's chief scientific officer. "There are now considerable data from our Phase 1 studies and those previously conducted by GlaxoSmithKline that suggest that maribavir may provide a safer and more tolerable alternative for patients with CMV infection."
"We expect to begin dosing patients in this trial within the next month," continued Dr. Broom. "If the safety and efficacy data from the Phase 2 program are positive, we would be in a position to initiate our pivotal Phase 3 program with maribavir as early as mid-2005."
The Phase 2 clinical trial is a randomized, double blind, placebo-controlled, dose-ranging study at up to 15 transplant centers involving CMV-seropositive subjects who have undergone allogeneic stem cell transplantation. Thirty-six subjects will be randomized into each of the three ascending dose groups, with 27 receiving maribavir and 9 receiving placebo in each group for a total of 108 subjects overall. The primary objective of this study is to evaluate the safety and tolerability of maribavir administered orally for up to 12 weeks. The secondary objectives are to evaluate the activity of maribavir in preventing CMV reactivation in CMV seropositive recipients of allogeneic stem cell transplants, to evaluate the pharmacokinetics of maribavir in this subject population, and to select a dose or doses of maribavir to be used in the Phase 3 program.
The new preliminary data presented at the pre-Phase 2 investigator's meeting were from two Phase 1 trials with maribavir conducted by ViroPharma. In February 2004, ViroPharma initiated a Phase 1 drug interaction study in healthy volunteers, designed to evaluate the potential for maribavir to affect the blood levels of various other drugs that are metabolized by multiple cytochrome P450 liver enzymes. Pharmacokinetic data were collected before and during administration of a 400 mg dose of maribavir given twice a day for 10 days. In March 2004, the company initiated a second Phase 1 trial to evaluate the pharmacokinetic profile of a single 400 mg dose of maribavir in patients with varying levels of renal functional impairment, compared to subjects with normal renal function. In both studies, the preliminary safety, tolerability, and pharmacokinetic data have been favorable and support advancing maribavir to Phase 2 studies.
Maribavir is a benzimidazole compound being studied for the prevention and treatment of cytomegalovirus (CMV) infections. ViroPharma licensed maribavir from GlaxoSmithKline (GSK) in August 2003. Prior to that date, maribavir had been administered orally to 100 human subjects in several GSK Phase 1 studies.
CMV is a member of the herpes virus group, which includes the viruses that cause chicken pox, mononucleosis, herpes labialis (cold sores), and herpes genitalis (genital herpes). Like other herpesviruses, CMV has the ability to remain dormant in the body for long periods of time. Human CMV infection rates average between 50% and 85% of adults in the U.S. by 40 years of age. In most individuals with intact immune systems, CMV causes little to no apparent illness. However, in immunocompromised individuals, CMV can lead to serious disease or death. Before the availability of potent anti-HIV therapy, CMV associated retinitis was commonly seen in patients with HIV/AIDS. Currently, patients who are immunosuppressed following hematopoietic stem cell (e.g., bone marrow) or solid organ transplantation remain at high risk of CMV infection. In these patients, CMV can lead to severe conditions such as pneumonitis or hepatitis, or to complications such as acute or chronic rejection of a transplanted organ. ViroPharma is providing an audio archive of their recent Teach-In on CMV in an effort to provide additional information on CMV to investors. The audio archive and a downloadable version of the slides from the event can be accessed via the ViroPharma corporate website, www.viropharma.com and will be available until August 20, 2004.
ViroPharma Incorporated is committed to the development and commercialization of products that address serious diseases treated by narrowly focused prescribing groups. ViroPharma is currently focused on drug development activities in viral diseases including cytomegalovirus (CMV) and hepatitis C (HCV).
Certain statements in this press release contain forward-looking statements that involve a number of risks and uncertainties, including those relating to ViroPharma's hope to develop maribavir into a leading anti-CMV drug by providing transplant patients an effective option with an improved safety profile; ViroPharma's plan to begin dosing patients with maribavir in its Phase 2 study within the next month; ViroPharma's plan to initiate a pivotal Phase 3 clinical study in mid-2005; ViroPharma's hope that maribavir may one day provide patients with a viable alternative for reducing the risks of CMV infection that is safer and more tolerable than currently available treatments. Our actual results could differ materially from those results expressed in, or implied by, these forward-looking statements. There can be no assurance that any of the events described in the forward-looking statements identified in this press release will occur. Conducting clinical trials for investigational pharmaceutical products is subject to risks and uncertainties. There can be no assurance that planned clinical trials can be initiated, or that planned or ongoing clinical trials can be successfully concluded or concluded in accordance with ViroPharma's anticipated schedule, or that maribavir will achieve proof of concept. Also, the earlier Phase 1 data of maribavir in HIV-infected patients with CMV retinitis, and the preliminary Phase 1 data from trials conducted by ViroPharma, are not necessarily predictive of maribavir's safety or efficacy in the transplant patients. These factors, and other factors, including, but not limited to those described in ViroPharma's most recent annual report on Form 10-K and registration statements on Forms S-3 and S-4 filed with the Securities and Exchange Commission, could cause future results to differ materially from the expectations expressed in this press release. The forward-looking statements contained in this press release may become outdated over time. ViroPharma does not assume any responsibility for updating any forward-looking statements.