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Rib-X Presents Data from Multiple Radezolid Studies at ICAAC Including Successful Intravenous Dosing in Phase 1 and Favorable Long-term Safety and Tolerability vs. Linezolid In Vivo

NEW HAVEN, Conn.--(BUSINESS WIRE)--Sep 11, 2012 - Rib-X Pharmaceuticals, Inc. announced today that the Company's next-generation oxazolidinone, radezolid, was featured in one oral and three poster presentations at the 52nd Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), taking place September 9-12, 2012 in San Francisco, CA. New data presented by Rib-X included the results from a positive Phase 1 intravenous (IV) dosing study conducted in healthy subjects and an in vivo long-term safety study versus linezolid. Third-party presentations highlighted radezolid as a promising next-generation oxazolidinone with a favorable long-term safety profile, IV and oral dosing potential, and potent activity against multiple linezolid-resistant Gram-positive strains.

Radezolid is a next-generation oxazolidinone designed to be a potent antibiotic with intravenous (IV) and oral formulations and a safety profile permitting long-term treatment of resistant infections, including those caused by methicillin-resistant Staphylococcus aureus (MRSA). Radezolid has completed two Phase 2 clinical trials with an oral formulation in uncomplicated skin and skin structure infections (uSSSI) and in community acquired bacterial pneumonia (CABP). A Phase 1 study with an IV formulation was recently completed in healthy subjects.

“Radezolid has shown promise as a next-generation oxazolidinone with the potential to overcome the shortcomings of existing antimicrobial treatments with favorable safety and tolerability that continues to hold at higher doses and over a longer period of time,” said Andrea Marra, Ph.D., Director of Preclinical Development at Rib-X. “The need for antibiotics that safely treat a broader spectrum of infections, not to mention those which have shown resistance to linezolid, is growing. This latest cohort of studies tested radezolid against a diverse set of challenges that have presented in the infection space, and the candidate has thus far succeeded in addressing the issues.”

Data from the Phase 1 IV dosing study was presented in poster A-1290, “A Phase 1 Single and Multiple Ascending Intravenous (IV) Dose Study of Safety and Pharmacokinetics (PK) of Radezolid (RDZ) in Healthy Subjects.” The study was a randomized, double-blind, placebo-controlled, single-center study of IV radezolid administered once daily for up to 14 days. The IV formulation of radezolid was well tolerated in healthy subjects and approximately dose proportional in single or multiple daily doses up to 14 days. The ability of radezolid to be administered either orally or through IV greatly increases its potential utility as a treatment option for drug-resistant and gram-positive bacteria.

Data from a 3-month in vivo toxicology study was presented in poster A-1289, “Radezolid Demonstrates Favorable Safety Compared to Linezolid in a Three-Month Rat Toxicology Study.” Radezolid and existing approved treatment, linezolid, were dosed in concurrent studies, which showed radezolid to be well-tolerated at all dose levels. No clinical signs were observed at any dose level for radezolid, resulting in a No Observed Adverse Effect Level (NOAEL) of 200 mg/kg/day. High-dose groups for linezolid exhibited decreased body weight and food consumption with associated clinical and hematological effects.

In a talk entitled, “New Oxazolidinones, Including Tedizolid (Torezolid, TR-700),” George M. Eliopoulos, M.D., highlighted new oxazolidinones that have emerged showing the potential as successors to existing treatments with improved antimicrobial or pharmacological attributes. Radezolid, being one of these oxazolidinones, has faced a variety of studies to examine its long-term safety and pharmacokinetics as it aims to fulfill needs left by existing treatments such as linezolid.

Additional information about Radezolid:

Through a rational drug design process involving approximately 700 prototype compounds, Rib-X developed radezolid to have structural advantages that make it a candidate for use as a treatment for serious infections, such as ABSSSI and severe CABP, and long-term treatment of underserved serious infections, such as osteomyelitis and prosthetic and joint infections. The demonstrated broad- spectrum of coverage, potency and potential long-term safety profile of radezolid could give it the potential to become the antibiotic of choice for multiple resistant bacterial infections, and for treatment in populations, such as the elderly and children, that might be vulnerable to myelosuppression caused by other oxazolidinone treatments.

About Rib-X:

Rib-X Pharmaceuticals, Inc. is a biopharmaceutical company developing new antibiotics to provide superior coverage, safety and convenience for the treatment of serious and life-threatening infections. The Company's proprietary drug discovery platform provides an atomic-level, three-dimensional understanding of interactions between drug candidates and their bacterial targets and enables design of antibiotics with enhanced characteristics. Rib-X has two antibiotic candidates in clinical development. Delafloxacin is an enhanced spectrum IV/oral antibiotic intended for use as first-line monotherapy primarily in hospitals and recently completed a Phase 2b clinical trial for the treatment of acute bacterial skin and skin structure infections. Radezolid is a next-generation IV/oral oxazolidinone designed to be a potent antibiotic with a safety profile permitting long-term treatment of resistant infections. The Company's pipeline also includes its preclinical RX-04 program, partnered with Sanofi, S.A., and other discovery stage anti-infective programs.


Contact: Company
Rib-X Pharmaceuticals, Inc.
Bob Conerly, 203-624-5606
Media Relations
For Rib-X Pharmaceuticals, Inc.
Kari Watson, 781-235-3060


Posted: September 2012