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BioCryst Reports Positive Results from Part One of Its Phase 2a Study of BCX4208 in Patients with Gout

The study's primary endpoint is the change in serum uric acid concentration after 21 days of treatment compared to baseline concentration prior to treatment. Part one of the study randomized 60 gout patients with serum uric acid concentrations greater than or equal to 8 mg/dL to placebo or to one of three different doses of BCX4208, a purine nucleoside phosphorylase (PNP) inhibitor, administered once-daily for 21 days. All three doses of BCX4208 demonstrated a statistically significant reduction in serum uric acid levels compared to placebo at day 22. BCX4208 doses of 40 mg, 80 mg and 120 mg per day showed median reductions in serum uric acid levels of 2.7, 3.3 and 3.4 mg/dL, respectively.

The median reductions of serum uric acid concentrations for these three doses ranged from 32.2 to 34.6 percent of baseline level. BCX4208 also demonstrated a statistically significant difference in the proportion of subjects with uric acid levels less than 6 mg/dL, compared to subjects treated with placebo, on day 22. Among patients with a baseline uric acid concentration below 10 mg/dL, up to 63 percent showed uric acid levels below 6 mg/dL on day 22.

BCX4208 was generally safe and well-tolerated at the doses evaluated in part one of this study. Reductions in peripheral blood lymphocytes were observed in patients treated with BCX4208. The protocol included stopping rules for CD4+ cell counts below certain thresholds; no subjects were discontinued for this reason and all 60 subjects completed the first part of this study. Overall, the frequency of adverse events in each of the BCX4208 treatment groups was comparable to that observed in the placebo group. All patients received prophylactic medicine for gout flares; the incidence of gout flares observed was low. Additional studies designed to evaluate longer-term exposure are needed to further define the safety and tolerability profile of BCX4208.

Part two of the study, designed to sequentially evaluate the safety and efficacy of up to three higher doses of BCX4208, is now under way. Following completion of the study, detailed results will be submitted for presentation at an upcoming scientific meeting.

"Novel therapeutics are urgently needed for the growing patient population with chronic or frequently recurrent gout. The results from this study of BCX4208 are encouraging, since they reveal rapid and substantial urate lowering by targeting PNP with an oral compound," stated Robert Terkeltaub, M.D., VA Rheumatology Section Chief, San Diego Professor of Medicine. "BCX4208, the only PNP inhibitor in development for gout, could prove particularly useful in combination therapy strategies tailored to safely and effectively reduce the symptoms associated with high serum urate in difficult to treat gout patients."

"This successful first clinical test of BCX4208 in patients with gout confirms this PNP inhibitor's ability to reduce uric acid levels in the blood and supports its continued evaluation as a potential treatment for patients with gout," said Dr. William P. Sheridan, Chief Medical Officer at BioCryst. "We have started part two of this study and we are finalizing plans for an additional Phase 2 trial of BCX4208 as a monotherapy and in combination with allopurinol, a commonly used urate-lowering treatment for gout. During 2010 we expect to complete these studies, which should define dosing suitable for further development of BCX4208 for gout."

Conference Call and Web Cast

BioCryst's management team will host a conference call and web cast on Wednesday, April 28, 2010 at 11:00 a.m. Eastern Time to discuss the results of this BCX4208 gout study and its first quarter financial results. To participate in the conference call, please dial 1-877-303-8027 (United States) or 1-760-536-5165 (International). No passcode is needed for the call. The web cast can be accessed by logging onto http://www.biocryst.com. Please connect to the web site at least 15 minutes prior to the start of the conference call to ensure adequate time for any software download that may be necessary.

About BCX4208

BCX4208 is a next generation purine nucleoside phosphorylase (PNP) inhibitor with the potential for once-a-day dosing suitable for chronic administration. Previous studies have shown that BCX4208 may have utility in diseases dependent on T-cells, B-cells or uric acid. With its novel mechanism of action, BCX4208 has the potential to address unmet medical needs across a broad spectrum of inflammatory diseases, including gout.

About Gout

Gout is an inflammatory arthritis that affects up to five million people in the U.S. Gout is caused by higher-than-normal uric acid in the blood, (a condition known as hyperuricemia) that may lead to the buildup of uric acid in synovial fluid around joints and the formation of monosodium urate crystals that result in painful joint inflammation. More information regarding gout and hyperuricemia is available at: http://www.cdc.gov/arthritis/basics/gout.htm

About BioCryst

BioCryst Pharmaceuticals designs, optimizes and develops novel small-molecule pharmaceuticals that block key enzymes involved in infectious diseases, cancer and inflammatory diseases. BioCryst has progressed two novel compounds that are in late-stage pivotal clinical trials; peramivir, an anti-viral for influenza, and forodesine, a purine nucleoside phosphorylase (PNP) inhibitor for cutaneous T-cell lymphoma (CTCL). Additionally, BioCryst has a third product candidate, BCX4208-a next generation PNP inhibitor—in mid-stage trials for the treatment of gout. Utilizing crystallography and structure-based drug design, BioCryst continues to discover additional compounds and to progress others through pre-clinical and early development to address the unmet medical needs of patients and physicians. For more information, please visit the Company's Web site at www.biocryst.com.

Forward-Looking Statements

This press release contains forward-looking statements, including statements regarding future results, performance or achievements. These statements involve known and unknown risks, uncertainties and other factors which may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements. These statements reflect our current views with respect to future events and are based on assumptions and subject to risks and uncertainties. Given these uncertainties, you should not place undue reliance on these forward-looking statements. Some of the factors that could affect the forward-looking statements contained herein include: that we or our licensees may not be able to enroll the required number of subjects in planned clinical trials of our product candidates and that such clinical trials may not be successfully completed; that our product candidates may not receive required regulatory clearances from the FDA; that ongoing and future preclinical or clinical development and commercialization of our product candidates, including peramivir, forodesine, BCX4208 and other PNP inhibitor and hepatitis C development programs, may not have positive results; that we or our licensees may not be able to continue future development of our current and future development programs; that our development programs may never result in future product, license or royalty payments being received by BioCryst; that BioCryst may not be able to retain its current pharmaceutical and biotechnology partners for further development of its product candidates or it may not reach favorable agreements with potential pharmaceutical and biotechnology partners for further development of its product candidates; that BioCryst may not have sufficient cash to continue funding the development, manufacturing, marketing or distribution of its products and that additional funding, if necessary, may not be available at all or on terms acceptable to BioCryst. Please refer to the documents BioCryst files periodically with the Securities and Exchange Commission, specifically BioCryst's most recent Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, and current reports on Form 8-K, all of which identify important factors that could cause the actual results to differ materially from those contained in our projections and forward-looking statements.

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BioCryst Pharmaceuticals, Inc.
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Catherine Collier Kyroulis, +1-212-301-7174 (Media)