BioCryst Pharmaceuticals, Inc. (NASDAQ:BCRX) today announced that it has dosed the first subject in OPuS-1 ( Oral Prophylaxi S-1), a Phase 2a proof of concept clinical trial of orally-administered BCX4161 in patients with hereditary angioedema (HAE). The OPuS-1 trial will test 400 mg of BCX4161 administered three times daily for 28 days in up to 25 HAE patients who have a high frequency of attacks (≥ 1 per week), in a randomized, placebo-controlled, two-period cross-over design. The main goals for the OPuS-1 trial are to estimate BCX4161’s degree of efficacy in reducing the frequency of angioedema attacks, and to evaluate the safety and tolerability of 28 days of BCX4161 treatment. “We look forward to obtaining the results of OPuS-1, the first trial of an oral kallikrein inhibitor in HAE patients. The safety, tolerability, drug exposure and kallikrein inhibition achieved in the Phase 1 healthy volunteer trial of BCX4161 strongly support its further evaluation in HAE patients,” said Dr. William P. Sheridan, Chief Medical Officer at BioCryst. “OPuS-1 is another step toward our goal of improving HAE patients’ lives by dramatically changing the management of this disease.” The Phase 2a OPuS-1 trial is being conducted at up to four centers in Germany and will evaluate the efficacy, safety, tolerability, pharmacokinetics and pharmacodynamics of BCX4161. Each subject will receive BCX4161 and placebo in two separate 28-day periods, with the order of therapy randomized (placebo followed by BCX4161 or BCX4161 followed by placebo). The primary efficacy endpoint for the OPuS-1 trial is the mean attack frequency in each period. Other efficacy measures include average severity of attacks, the number of attack-free days and quality of life. As a part of BioCryst’s strategy to become a leader in the treatment of HAE, its scientists are finalizing the evaluation of multiple potent and specific second generation oral kallikrein inhibitors, with the goal of developing compounds with potential for once daily dosing. One to three candidates are expected to enter preclinical development before the end of 2013.