Rib-X Pharmaceuticals, Inc., a development-stage company focused on the discovery, development and commercialization of novel antibiotics for the treatment of antibiotic-resistant infections, today announced positive results from a Phase 2 clinical trial with the oral form of its compound, radezolid (RX-1741), for the treatment of uncomplicated skin and skin structure infections (uSSSI).
These results were announced at the 48th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC)/Infectious Diseases Society of America (IDSA) 46th annual meeting (2008 ICAAC/IDSA Joint Meeting) held October 25 – 28 in Washington, D.C.
The open-label trial met both its primary (efficacy) and secondary (safety) endpoints. All doses of radezolid were as efficacious as linezolid (Zyvox®, currently marketed by Pfizer) and demonstrated a good safety profile.
The study also showed that radezolid was approximately four times more potent than linezolid against bacteria cultured from subjects in the study, including against methicillin-resistant Staphylococcus aureus (MRSA), with MIC90s of 0.5mg/L and 2.0mg/L respectively. MIC90s for other relevant bacterial isolates in the study were 0.5mg/L and 2.0mg/L for MRSA and 0.25mg/L and 1.0ug/ml for Streptococcus pyogenes for radezolid and linezolid, respectively.
MIC90 is defined as the minimum inhibitory concentration necessary to inhibit the growth of 90 percent of the bacteria.
"We are pleased to report that our novel oxazolidinone, radezolid, may provide a safe and more potent alternative to the only currently marketed drug in this antibiotic class," said Susan Froshauer, PhD, President and CEO of Rib-X Pharmaceuticals. "In particular, radezolid offers a broader spectrum that includes atypicals and Haemophilus influenzae and a once-a-day option at a significantly lower dose than linezolid. Additionally, these results further validate Rib-X's proprietary discovery and development approach which led to the identification of this compound as well as multiple other novel compounds in various classes which are able to circumvent bacterial resistance mechanisms."