BioCryst Pharmaceuticals, a Durham, N.C.-based and developer of novel small molecule drugs that block key enzymes involved in infectious and inflammatory diseases, and Presidio Pharmaceuticals, a San Francisco-based clinical stage specialty pharmaceutical company, have signed a definitive merger agreement for Presidio to be acquired by BioCryst in an all-stock transaction.

The transaction has been approved by the boards of both companies. The transaction values Presidio at approximately $101 million, based on the closing BioCryst share price of $4.11 per share. The transaction is expected to close in the first quarter of 2013, and is subject to customary conditions, including approval by BioCryst shareholders.

The combined company will launch under a new name and will be headquartered in Durham, N.C., with facilities in San Francisco and Birmingham, Alabama. The proposed board of directors of the new company will consist of three Presidio nominees and six BioCryst nominees. Jon P. Stonehouse, current president and CEO of BioCryst, will serve as the CEO of the combined company and Kenneth Galbraith, current chairman of Presidio, will be the non-executive chairman of the board.

The merger creates a focused, clinical stage biopharmaceutical company with lead programs in high-value infectious and orphan disease indications: hepatitis C (HCV) and hereditary angioedema (HAE). This new entity will own a portfolio of three oral, pan-genotypic antivirals that are suitable either for development in combination with each other or in combination with other direct acting antivirals (DAAs) to treat patients with HCV infection.

"We're creating this new company to pursue the development and commercialization of antiviral and orphan drugs. Presidio brings exciting HCV assets to the new company, and a highly experienced scientific team with a proven track record in antiviral drug discovery and development," said Stonehouse. "Each of our HCV antivirals works via a different targeting mechanism and each is suitable for development in combination regimens with other classes of HCV inhibitors. The diversity of our HCV portfolio reduces our clinical development risk and defines this new company as a serious competitor in the development of orally administered, safe and effective combination therapies for hepatitis C."

Richard Colonno, CSO of Presidio, added, "Our initial focus will be on commencing HCV curative phase IIa combination trials with our NS5A inhibitor PPI-668, while advancing both our nucleoside and non-nucleoside inhibitors through phase I proof-of-concept trials next year."

The merger is subject to customary closing conditions, including approval of the transaction by BioCryst shareholders, as well as completion of a minimum $60 million equity financing on commercially reasonable terms. In total, subject to adjustment based on Presidio's working capital at closing and certain other factors, BioCryst will issue a total of 24.5 million shares of its common stock to Presidio's shareholders in exchange for all of the outstanding shares of Presidio and the $25 million of new cash financing committed by certain Presidio shareholders.