ViroPharma Receives Orphan Drug Designation For Maribavir In Europe

EXTON, Pennsylvania, June 11, 2013 /PRNewswire/ -- ViroPharma Incorporated (Nasdaq: VPHM) today announced that the European Commission has granted orphan drug designation for maribavir for treatment of cytomegaloviral (CMV) disease in patients with impaired cell mediated immunity. The "Orphan Medicinal Product Designation" is designed to encourage the development of drugs which may provide significant benefit to patients suffering from rare diseases identified as "life-threatening or chronically debilitating" conditions. ViroPharma has previously received orphan drug designation for maribavir in the United States for treatment of clinically significant cytomegalovirus viremia and disease in at-risk patients.

Under EMA guidelines, Orphan Medicinal Product Designation provides 10 years of potential market exclusivity if the product candidate is approved for marketing in the European Union and the orphan designation is maintained. Orphan status also permits EMA assistance in optimizing the candidate's clinical development through participation in designing the clinical protocol and preparing the marketing application. Additionally, a drug candidate designated by the EMA as an Orphan Medicinal Product may qualify for a reduction in regulatory fees as well as a European Union-funded research grant. Finally, if a Pediatric Investigation Plan is completed, an additional two years of exclusivity could be granted for a product with Orphan Medicinal Product designation.

"We are very pleased to receive orphan designation for maribavir from the European Commission," commented John Watson, ViroPharma's senior director, regulatory affairs, Europe. "This designation recognizes the potential of maribavir to address great unmet medical needs. We commend the European Commission for providing incentives such as this for the development of drugs for rare and life threatening diseases."

ViroPharma is currently conducting two Phase 2 dose ranging studies of oral maribavir at one of three doses (400mg, 800mg or 1200mg BID) in transplant recipients. The first is a randomized, active (valganciclovir) controlled maribavir dose blinded multicenter Phase 2 study in up to 160 European hematopoietic stem cell or solid organ transplant recipients who have demonstrated CMV viremia but do not have CMV organ disease. ViroPharma is also conducting a randomized, dose blinded multicenter Phase 2 study intended to enroll up to 120 hematopoietic stem cell or solid organ transplant recipients who have resistant or refractory CMV viremia with or without CMV organ disease. This study is currently being conducted in the US with plans to extend to include European sites.

ViroPharma Incorporated is based in Exton, Pennsylvania, US, and also has offices in Canada and in eight European countries including Belgium, France, Germany, Italy, Spain, Sweden, Switzerland and the United Kingdom. ViroPharma is continuing to grow its footprint and presence in Europe, and to support this growth, ViroPharma's European operations were initiated in 2007, leveraging in Europe the company's expertise in the development and commercialisation of biotechnology products, and in business development.

About maribavir
Maribavir, a member of a new class of drugs called benzimidazole ribosides, is a potent and selective, orally bioavailable antiviral drug with a unique mechanism of action against cytomegalovirus and a favorable clinical safety profile. Unlike currently available anti-CMV agents that inhibit CMV DNA polymerase, maribavir inhibits viral DNA assembly and inhibits egress of viral capsids from the nucleus of infected cells. Maribavir is active in vitro against strains of CMV that are resistant to commonly used anti-CMV drugs. Maribavir does not affect the maturation of viral DNA or affect the viral DNA polymerase. The previous focus of clinical development of maribavir as an anti-CMV agent was on the prevention of CMV disease in transplant patients. Results from Phase 3 studies indicated that maribavir at a dose of 100mg BID failed to meet its efficacy endpoints. However, maribavir has demonstrated a favorable safety and tolerability profile; across all clinical studies to date, the most notable adverse event associated with maribavir was taste disturbance. While Phase 3 studies of CMV prophylaxis at the 100mg BID dose did not show sufficient activity to prevent CMV disease, the overall safety profile of maribavir and limited data from cases in which open-label maribavir was used as CMV treatment suggest that higher doses may provide clinical activity and clinical studies are ongoing. The U.S. Food and Drug Administration (FDA) and the European Commission have granted orphan drug designation to maribavir for treatment of clinically significant cytomegalovirus viremia and disease in at-risk patients, and treatment of cytomegalovirus disease in patients with impaired cell mediated immunity, respectively.

About Cytomegalovirus
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 percent and 85 percent of adults in the U.S. by 40 years of age, but in healthy adults causes little to no apparent illness. However, in immunocompromised individuals including cancer patients, HIV patients, and transplant patients, and in children born with primary CMV infection, CMV can lead to serious disease or death. Patients who are immunosuppressed following hematopoietic stem cell (bone marrow) or solid organ transplantation are 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. While currently available systemic anti-CMV agents are effective against the virus, their use is limited by toxicities, most notably bone marrow suppression and renal impairment.

About ViroPharma Incorporated
ViroPharma Incorporated is an international biopharmaceutical company committed to developing and commercializing novel solutions for physician specialists to address unmet medical needs of patients living with diseases that have few, if any, clinical therapeutic options, including C1 esterase inhibitor deficiency, treatment of seizures in children and adolescents, adrenal insufficiency, and C. difficile infection (CDI). Our goal is to provide rewarding careers to employees, to create new standards of care in the way serious diseases are treated, and to build international partnerships with the patients, advocates, and healthcare professionals we serve.

ViroPharma routinely posts information, including press releases, which may be important to investors in the investor relations and media sections of our company's website, http://www.viropharma.com/. The company encourages investors to consult these sections for more information on ViroPharma and our business.

Forward-Looking Statements
Certain statements in this press release contain forward-looking statements that involve a number of risks and uncertainties. Various known and unknown risks, uncertainties and other factors could lead to material differences between the actual future results, financial situation, development or performance of the company and the estimates given here. Forward-looking statements in this press release include statements regarding potential therapeutic indication and use of maribavir and regarding maribavir's potential to address unmet medical needs. The development and commercialization of pharmaceutical products is subject to risks and uncertainties. There can be no assurance that studies with maribavir will generate positive results or that maribavir will receive regulatory approvals. The EMA may view data regarding maribavir as insufficient or inconclusive, request additional data, require additional clinical studies, limit any approved indications, deny the approval of maribavir or deny orphan drug market exclusivity at the time of any future approval. A full list and description of risks and uncertainties can be found in ViroPharma's Annual Report on Form 10-K for the fiscal year ended December 31, 2012, and 10-Q for the quarter ended March 31, 2013 filed with the Securities and Exchange Commission. The forward-looking statements contained in this press release are made as of the date hereof and may become outdated over time. ViroPharma does not assume any responsibility for updating any forward-looking statements. These forward-looking statements should not be relied upon as representing our assessments as of any date subsequent to the date of this press release.