BioCryst Updates Peramivir Clinical Development Plan

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Following release of preliminary Phase II results in September 2007, the Company completed additional analyses of the clinical data and performed a preliminary analysis of the virologic data from this trial. The Company also conducted further pharmacokinetic (PK) studies in healthy volunteers and has had discussions with the FDA and The Department of Health and Human Services (HHS) in support of the continuing development of peramivir.

Preliminary analysis of the virologic data from the Phase II trial indicated that i.m. peramivir demonstrated statistically significant reductions in influenza virus shedding in both active treatment groups when compared to placebo, with greater reductions in the 300mg group (p<0.001). Additionally, pharmacokinetic studies have been completed that indicate that needle length impacts adequate and consistent systemic exposure to i.m. peramivir. These PK studies also provide guidance on the appropriate needle length to use in future studies to provide adequate drug exposure for subjects based upon an individual''s body mass index (BMI) and gender.

Based on these clinical results and virologic data, the Company believes that a single i.m. dose of 300mg peramivir can be a potentially clinically effective dose. Given the dose-response observed between the 150mg and 300mg doses in the Phase II trial, the Company also believes it is prudent to evaluate whether doses higher than 300mg provide additional efficacy. The Company has been limited in evaluating doses higher than 300mg due to the concentration of the formulation used in the Phase II trial. Alternative formulations are being developed, and should be available, that permit evaluation of a single dose higher than 300mg. BioCryst is now planning to initiate a Phase II clinical trial that will evaluate the 300mg dose and a higher dose of peramivir later this year. As a result, BioCryst will not continue to pursue a pivotal Phase III program for i.m. peramivir in the current influenza season.

"All of these analyses have reinforced our belief that adequate and consistent systemic exposure to peramivir is critical to demonstrate the clinical benefits of peramivir," said Jon P. Stonehouse, President and CEO of BioCryst. "This strategy allows us to test a higher dose, utilize a new formulation and make the adjustments in needle-length, all in one study. This strategy gives us confidence that we can maximize the likelihood of achieving a successful result."

After discussions between BioCryst and HHS, the Company believes that peramivir remains an important potential therapy for both seasonal influenza and pandemic preparedness. The key elements of the HHS contract remain the same. The contract amount is $102.6M and the term is four years (concluding December 31, 2010). The development plan for peramivir has changed from that outlined in the original proposal to HHS. HHS has indicated that they will fund certain elements of the revised program, including the ongoing Phase II i.v. study in hospitalized subjects, planning and conduct of the planned Phase II i.m. study, manufacturing and toxicology. Each of these elements has specific HHS funding limits. Any costs in excess of these limits will be the responsibility of BioCryst. The Company anticipates that the full peramivir program will cost more than the original contract amount. HHS has indicated that, at this time, they will not fund certain elements of the revised program, and those costs may be the responsibility of BioCryst. On an ongoing basis, HHS will play a more active role in the program, and in reviewing related spending under this contract.

Mr. Stonehouse added, "We are pleased with HHS''s continued support of peramivir. HHS support is critical in taking the next steps in the development of peramivir. A future pandemic remains a serious threat to global health. Additionally, seasonal influenza and related complications result in an estimated 40,000 deaths in the United States annually. We will work diligently to move both the i.v. and i.m. formulations of peramivir forward toward registration in order to make this potentially important therapy available to patients."

BioCryst will sponsor a conference call at 8:00 am Eastern U.S. Time, Thursday, January 24, 2008 to discuss today''s news in more detail. This call is open to the public and can be accessed live either over the Internet from the company''s website or by dialing 1-800-860-2442 (U.S.) or 1-412-858-4600 (international). No passcode is needed for the call.

About Peramivir

Peramivir is a member of the class of antiviral agents that inhibit influenza viral neuraminidase, an enzyme essential for the spread of influenza virus within the host. The availability of an injectable neuraminidase inhibitor may be important in treating patients with acute, severe and potentially life-threatening influenza and could ensure appropriate dosing which may be a concern with currently available oral or inhaled anti-influenza agents. In January 2007, the U.S. Department of Health and Human Services (HHS) awarded a $102.6 million, four-year contract to BioCryst for advanced development of peramivir to treat seasonal and life-threatening influenza. In the United States, intravenous peramivir injection has received Fast Track designation from the Food and Drug Administration (FDA).

About Influenza