Rib-X Pharmaceuticals Receives Qualified Infectious Disease Product (QIDP) Designation from the FDA for Delafloxacin

Rib-X among the first to receive QIDP designation under the new Generating Antibiotic Incentives Now (GAIN) program

Delafloxacin is designated as a QIDP for the indications of acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP)

Rib-X Pharmaceuticals Receives Qualified Infectious Disease Product (QIDP) Designation from the FDA for Delafloxacin

<0> Rib-X Pharmaceuticals, Inc.Bob Conerly, 203-624-5606orMedia RelationsKari Watson, 781-235-3060 </0>

today announced that the Food and Drug Administration (FDA) designated delafloxacin as a Qualified Infectious Disease Product (QIDP) for the indications of acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP). The QIDP designation will enable Rib-X to benefit from certain incentives for the development of new antibiotics, including an additional five years of market exclusivity, priority review and eligibility for fast-track status, provided under the new Generating Antibiotic Incentives Now (GAIN) program. GAIN was included in the FDA Safety and Innovation Act (FDASIA), formerly known as PDUFA V, which received bipartisan Congressional support and was signed into law by President Obama in July 2012.

"This Connecticut company is at the forefront of fighting super germs by developing new antibiotics to conquer increasingly resistant infections," said Senator Richard Blumenthal (D-CT), who was responsible for the addition of the GAIN Act to FDASIA. "Using incentives provided by new legislation, Rib-X can invent cutting edge biotech cures that save lives and cut health care costs."

Delafloxacin is being developed for use as an effective and convenient first-line antibiotic primarily in hospitals prior to the availability of a specific diagnosis. Delafloxacin has the potential to offer broad spectrum coverage as a monotherapy, including for methicillin-resistant (MRSA), with both intravenous (IV) and oral formulations. With the exception of Zyvox (linezolid), all other currently approved treatments for MRSA offer only IV delivery. In addition to strong Gram-positive potency, delafloxacin has shown excellent activity against susceptible Gram-negative bacteria. Rib-X recently from a successful Phase 2b study in which delafloxacin met or exceeded primary and secondary efficacy endpoints evaluated in comparison to Zyvox, with and without aztreonam, and vancomycin, with and without aztreonam, including endpoints based on the new draft guidance from the US Food and Drug Administration (FDA) for ABSSSI.

“We are pleased to be one of the first companies to receive QIDP designation from the FDA for delafloxacin. The GAIN program was created as a stimulus to help address the urgent medical need and humanitarian need for new life saving antibiotics that can combat the growing problem of drug resistance,” said Mark Leuchtenberger, Chief Executive Officer of Rib-X. “We believe delafloxacin is a prime example of the kind of drug that was envisioned by the creators of GAIN based on its potential utility as a well-tolerated, broad spectrum antibiotic that effectively targets resistant pathogens. As we move forward with the design of what we believe will be a de-risked Phase 3 program for delafloxacin, priority review, the eligibility for fast-track status, and an additional five years of market exclusivity are important added benefits to aid the advancement of this candidate, on top of positive Phase 2b data against the FDA’s new objective endpoints for ABSSSI.”

Delafloxacin has been in four Phase 2 trials where it has shown promising results for the treatment of lung infections, including pneumonia and bronchitis, and skin infections. Rib-X is developing both IV and oral formulations of delafloxacin to enable patients who begin IV treatment in the hospital setting to transition to oral dosing for home-based care, offering the potential to increase patient convenience, lower the overall cost of treatment and reduce the length of hospital stays. These attributes, combined with delafloxacin’s safety profile and reduced probability of resistance, demonstrate the potential of delafloxacin to become a new standard of care for first-line treatment of serious infections and thereby reduce the need to switch to second-line, narrow spectrum antibiotics.

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.