Rib-X Pharmaceuticals Inc. raised $50 million in its Series C round to fund development of its two clinical-stage antibiotics, including the first program to emerge from its drug discovery engine.
Money will be used to advance the company's Rx-01 program, which is in Phase I testing as both an oral and intravenous agent for hospital-acquired, Gram-positive infections. Rib-X also plans to begin its own clinical testing of WQ-3034, a Phase II-stage broad-spectrum quinolone antibiotic licensed earlier this month from Osaka, Japan-based Wakunaga Pharmaceutical Co. Ltd., said Susan Froshauer, president and CEO of New Haven, Conn.-based Rib-X.
"At the same time, we'll continue to build a pipeline through our research organization," she said, "which involves using a very beautiful, high-resolution crystal structure of the 50S subunit of the ribosome" plus computational tools to design and build antibiotics.
The 50S subunit is a well-known target for antibiotics - New York-based Pfizer Inc.'s macrolide Zithromax (azithromycin) works by binding to that part of the ribosome - and Rib-X's platform aims to "customize and design next-generation antibiotics to target specific applications," while avoiding mechanisms that contribute to antibiotic resistance, Froshauer said. In fact, she believes it's that discovery engine, plus the research and development team, which includes Pfizer alumni Scott Hopkins and Joyce Sutcliffe, that has enabled the company to attract substantial investments since its 2001 inception.
To date, Rib-X has pulled in $123 million. Its last round of financing was a $63.5 million Series B that closed in May 2003. (See BioWorld Today, May 2, 2003.)
Froshauer said funds from the Series C round are anticipated to "take us to and through an [initial public offering], which we hope to have happen by the end of next year, depending on the market."
By then, Rib-X should be heading toward late-stage development. Rx-01 is expected to begin Phase II trials within the next year, and WQ-3034, which has shown activity against methicillin-resistant Staphylococcus aureus (MRSA) and penicillin-resistant Staphylococcus aureus in earlier trials conducted by Wakunaga, is expected to re-enter the clinic before the end of this year.
Rib-X gained an exclusive, worldwide license to WQ-3034 in exchange for an up-front fee, as well as potential milestones and royalties.
The company doesn't plan to rely on further in-licensing activities "unless something fabulous hits us between the eyes," Froshauer told BioWorld Today. Instead, the discovery platform "is going to guide development of our pipeline."
Ultimately, Rib-X would like to build its own sales force to handle antibiotics for hospital-acquired infections, though it likely will consider partnership opportunities for the larger community-acquired infection market.
"We'd like to have a blend of both," Froshauer said.
The round was led by New York-based Warburg Pincus, and included existing investors ABS Ventures; Hartford, Conn.-based Axiom Venture Partners; Princeton-based Cardinal Partners; New York-based EuclidSR Partners; Boston-based Oxford Bioscience Partners and West Conshohocken, Pa.-based S.R. One Ltd. New investors MedImmune Ventures Inc., of Gaithersburg, Md., and Radius Ventures, of New York, also participated.
Wayne Hockmeyer, of MedImmune Ventures, was named to Rib-X's board.