ViroPharma Incorporated Announces Completion of Enrollment in 500mg BID Arms of HCV-796 Phase 2 Study

EXTON, Pa., June 12 /PRNewswire-FirstCall/ -- ViroPharma Incorporated today announced that patient enrollment has been completed in the 500mg BID arms of the ongoing Phase 2 study in hepatitis C patients with HCV-796, a unique orally dosed non nucleoside hepatitis C viral polymerase inhibitor that interferes with the replication of hepatitis C virus (HCV). The Phase 2 study is being conducted with Wyeth Pharmaceuticals, a division of Wyeth , ViroPharma’s partner in development of HCV-796.

The companies expect to release four week treatment data from these arms in the third quarter of 2007, and 12 week treatment data in the fourth quarter of 2007. The companies are performing certain Phase 3 preparatory work at risk to allow initiation of the Phase 3 program as soon as possible.

“We are extremely pleased with our HCV-796 Phase 1b data, as well as the progress and interest in the program overall; our goal remains to be the ‘first in class’ among non nucleoside polymerase inhibitors, a class of compounds which we believe will play a significant role in future antiviral combination therapies for patients with hepatitis C,” commented Stephen Villano, ViroPharma’s vice president of clinical research and development. “Our Phase 1b data have helped elucidate the tolerability profile of HCV-796 and the strong antiviral activity of the drug in combination with pegylated interferon. We believe that, thus far, HCV-796 continues to be well- positioned for inclusion in future combination trials to assess improvement in the lives of those afflicted with hepatitis C and increased cure rates in these patients.”

The objectives of this Phase 2 trial are to assess the safety, tolerability, pharmacokinetic profile, and antiviral activity of HCV-796, when used in combination with pegylated interferon alfa-2b (PEG-Intron(R)) plus ribavirin (REBETOL(R)) compared to the current standard of care in treatment- naive subjects with HCV genotype 1 infection and in patients with HCV genotype 1 infection who were null-responders (who have failed to achieve a 2 log reduction in viral titer) following prior interferon based HCV therapy. The companies intend to add additional treatment cohorts to the trial to further elaborate antiviral activity.

Phase 2 Design

The Phase 2 study is a randomized, open-label study of the safety, tolerability, antiviral activity, and pharmacokinetics of HCV-796 administered in combination with pegylated interferon plus ribavirin versus pegylated interferon plus ribavirin (standard of care) in HCV genotype 1-infected subjects who are naive to treatment. The combination of HCV-796, pegylated interferon and ribavirin is also being assessed in a group of HCV genotype 1 patients who have previously failed treatment (null-responders). All dose cohorts will be treated for up to 48 weeks with combination therapy, and will be followed for a further 24-week period.

Patients have been enrolled into 3 dosing groups of at least 74 patients per group: (1) treatment naive patients receiving PEG-Intron and ribavirin (control therapy); (2) treatment naive patients receiving PEG-Intron, ribavirin, and 500 mg of HCV-796 every 12 hours; and (3) null-responders receiving PEG-Intron, ribavirin, and 500 mg of HCV-796 every 12 hours.

Outcomes assessed in the treatment groups will include: -- Antiviral activity and percentage of subjects with undetectable plasma HCV RNA levels at weeks 4, 12, 24, and 48; -- Percentage of subjects with sustained virologic response (SVR), defined as undetectable (less than 10 IU/mL, as measured by the Roche COBAS TaqMan(R) assay) plasma HCV RNA levels at 24 weeks after the end of treatment.

About Hepatitis C

Hepatitis C is a blood-borne virus recognized as a major cause of chronic hepatitis worldwide. The World Health Organization estimates that 170 million persons worldwide are infected with HCV, and three to four million persons are newly infected globally each year. According to the U.S. Centers for Disease Control and Prevention (CDC), about four million people in the U.S., or 1.8 percent of the population, are infected with HCV.

Currently, there is no specific antiviral agent directed against HCV that is commercially available, and no vaccine for prevention of HCV infection. Several interferon products are available worldwide, but there are substantial limitations to the use of these products when given as monotherapy or in conjunction with ribavirin in the treatment of chronic HCV infection. In addition to the relatively poor treatment response in patients infected with genotype 1 HCV, the most common strain in the U.S., Western Europe and Japan, the considerable side effects frequently associated with the use of interferon can lead to discontinuation of therapy in approximately 20 percent of patients.

About ViroPharma Incorporated

ViroPharma Incorporated is committed to the development and commercialization of products that address serious diseases treated by physician specialists and in hospital settings. ViroPharma commercializes Vancocin(R), approved for oral administration for treatment of antibiotic- associated pseudomembranous colitis caused by Clostridium difficile and enterocolitis caused by Staphylococcus aureus, including methicillin-resistant strains (for prescribing information, please download the package insert at http://www.viropharma.com/docs/Vancocin_pi_2007.htm ViroPharma currently focuses its drug development activities in viral diseases including cytomegalovirus (CMV) and hepatitis C (HCV). For more information on ViroPharma, visit the company’s website at http://www.viropharma.com.

Certain statements in this press release contain forward-looking statements that involve a number of risks and uncertainties including those relating to the company’s progress of its HCV clinical development program as well as its proposed timelines for release of clinical trial data, initiation of a Phase 3 program, and the Company’s belief that HCV-796 continues to be well-positioned for inclusion in future combination trials to assess improvement in the lives of those inflicted with hepatitis C and increased cure rates in these patients. Our actual results could differ materially from those results expressed in, or implied by, these forward-looking statements. Conducting clinical trials for investigational pharmaceutical products is subject to risks and uncertainties. The data that is described in this press release is preliminary and full analysis of the data, or further testing such as the ongoing Phase 2 clinical studies of HCV-796 with pegylated interferon, may not support any or all of the statements in this press release. There can be no assurance that ViroPharma’s additional HCV studies will yield positive results, that the FDA or other regulatory authorities will require additional or unanticipated studies or clinical trial outcomes before granting regulatory approval, or that ViroPharma will be successful in gaining regulatory approval of any of its HCV product candidates. These factors, and other factors, including, but not limited to those described in ViroPharma’s quarterly report on Form 10-Q for the quarter ended March 31, 2007 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.

PEG-Intron and REBETOL are registered trademarks of Schering-Plough Corporation.

ViroPharma Incorporated

CONTACT: William C. Roberts, Senior Director, Corporate Communications,+1-610-321-6288, or Robert A. Doody, Manager, Corporate Communications,+1-610-321-6290, both of ViroPharma Incorporated

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