New Haven, Connecticut, Dec. 19 /PRNewswire/ -- Rib-X Pharmaceuticals, Inc., a privately held biopharmaceutical company that is designing and developing next generation antibiotics, today announced that it had initiated Phase I trials of its first candidate for treating resistant infections. The candidate had been derived from the company's Rx-01 program, which utilizes X-ray crystallography and computational chemistry to facilitate drug design. The company also announced the recent presentation of several scientific studies at the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), in Washington, D.C.

"The start of our clinical trial and our ICAAC presentations document the substantial competitive advantage of our structure-based drug design approach," said Susan Froshauer, PhD, President and Chief Executive Officer of Rib-X. "One key asset for the Company is our high resolution X-ray crystallographic knowledge of the 50S subunit of the ribsome in Gram-positive bacteria, the clinically validated target for many commercially important antibiotics. This resource, together with our proprietary computational toolkit has allowed us to efficiently design and generate a family of enhanced oxazolidinone compounds effective against drug-resistant bacteria. These compounds will be useful in a wide range of hospital settings.

"Importantly, our program, in the course of one year, generated a group of approximately 700 compounds for evaluation. From this group, we have identified multiple clinical candidates -- this rapid success and high level of efficiency notably exceeds typical pharmaceutical metrics."

Rx-01 antibiotics are inhibitors of the ribosome, a complex cellular machine that catalyzes the chemical steps to produce proteins. The ribosome is composed of 2 complex subunits called the 30S and 50S ribosomal subunits. Rx-01 compounds bind to the larger 50S subunit. Many existing classes of antibiotics, including those used to treat both community- and hospital-acquired infections, are known to function by targeting the 50S. Among the classes of antibiotics that act this way are macrolides, ketolides and the oxazolidinones that contribute more than $3 billion to the annual antibiotic marketplace. Zithromax and Zyvox are examples of two such antibiotics.

Compounds from the Rx-01 program have excellent oral bioavailability and are active against multidrug-resistant Gram-positive pathogens including methicillin-resistant Staphylococcus aureus (MRSA) and the newest emerging threat of Zyvox(R)-resistant enterococci.

"Rib-X studies presented at ICAAC this year affirm that we have made substantial progress toward our goal of designing new and potent antibiotics that overcome resistance and expand the armamentarium against specific bacterial infections regarded as public health threats," said Dr. Froshauer. "A highly detailed knowledge of both the atomic structure of the ribosome, and our understanding of how this structure interacts with commercially available antibiotics, were essential to this progress."

Technical title: "Design at the Atomic Level: Synthesis of Biaryloxazolidinones as Potent, Orally Active Antibiotics" (Session 126, Paper F-1252, poster board 177)

Popular title: Designer Antibiotics for Use in Serious Bacterial Infections

Authors: J Zhou, A Bhattacharjee, S Chen, Y Chen, E Duffy, J Farmer, J Goldberg, R Hanselmann, J Ippolito, R Lou, A Orbin, A Oyelere, J Salvino, D Springer, J Tran, D Wang and Y Wu

About Rib-X Pharmaceuticals

Rib-X Pharmaceuticals is a small molecule drug discovery company focused on the structure-based design of new classes of anti-infective agents. The Company's drug discovery strategy is focused on the exploitation of its proprietary high-resolution crystal structure of the 50S subunit of the ribosome, which performs an essential role in the fundamental process of protein synthesis, and to which many known antibiotics bind. The 50S is the target for many clinically important classes of antibiotics, including those used to treat both community-acquired and hospital pathogens. The Company's integrated research approach combines state of the art, proprietary computational analysis, X-ray crystallography, medicinal chemistry, microbiology and biochemistry, allowing for the rapid synthesis of new agents, which avoid typical antibiotic resistance mechanisms. Utilizing these tools, Rib-X has what amounts to a map of the 50S subunit of the ribosome. The Company is utilizing this advantage in the optimization of leads and the creation of new classes of antibiotics.

For more information on the Rib-X mission, please visit the Company website.

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