Bayer AG, Bayer Pharmaceuticals Corporation (USA), and Paratek Pharmaceuticals, Inc. announced new pre-clinical data detailing potent in vivo and in vitro activity of the lead compound in a new class of antibiotics, called aminomethylcyclines (AMCs).

BAY 73-7388, which was discovered by Paratek as PTK 0796, is a novel, semi-synthetic antibiotic compound for IV use, and is currently being studied to target a wide range of clinically prevalent infections, including those caused by Gram-positive, Gram-negative, atypical and anaerobic bacteria, and those with multi-drug resistance.

Additionally, pre-clinical research has shown that the compound did not demonstrate cross-resistance to currently available agents.

The compound is the first in the AMC class to be selected for development. The class was designed using innovative proprietary medicinal chemistry to specifically address the growing problem of antibiotic resistance in the clinical setting.

A joint team of Bayer and Paratek scientists presented data demonstrating the compound's in vitro activity against resistant bacteria and efficacy in animal models at the 14th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in Prague, Czech Republic. Seven studies were presented at the meeting, including:

· "Activity of BAY 73-7388, a novel aminomethylcycline, and other antibiotic classes against resistance bacteria in vitro," Poster 925

· "Potent activity of BAY 73-7388, a novel aminomethylcycline, against susceptible and resistant gram-positive and gram-negative organisms," Poster 926

· "BAY 73-7388, a novel aminomethylcycline, exhibits potent efficacy in pulmonary murine models of infection," Poster 927

· "BAY 73-7388 is highly efficacious in animal models of intra-abdominal infections caused by a range of aerobic and anaerobic organisms, including VRE," Poster 928

· "BAY 73-7388 demonstrates greater activity than linezolid in a range of murine models of skin and soft tissue infection," Poster 929

· "Superior efficacy of BAY 73-7388, a novel aminomethylcycline, compared with linezolid and vancomycin in murine sepsis caused by susceptible or multiresistant staphylococci," Poster 930

· "BAY 73-7388, a novel aminomethylcycline, is highly active in vivo in a murine model of pneumococcal pneumonia," Poster 931

"Bayer has a long history in the research of anti-infective therapies and is committed to developing antibiotics that are active against both resistant and non-resistant bacteria," said Martin Springsklee, vice-president, Therapy Area Anti-Infectives, Product Development, Bayer Healthcare. "Pre-clinical studies have shown that BAY 73-7388 demonstrated potent in vitro activity against a wide range of clinical isolates. Additionally, the compound shows no cross-resistance to currently available classes of antibiotics. BAY 73-7388 shows great promise as a developmental candidate from a new antibiotic class to be investigated for treatment of patients who would otherwise have increasingly limited treatment options."

Stuart B. Levy, M.D., Co-founder and chief scientific officer of Paratek Pharmaceuticals, explained, "Infections in hospitals are becoming increasingly difficult to treat, in large part because of rising bacterial resistance, and novel agents from new classes are needed. Designed as the lead compound in a new class, BAY 73-7388 has demonstrated broad activity against a wide variety of important resistant Gram-positive, Gram-negative, atypical and anaerobic bacteria. With such a spectrum, BAY 73-7388 has the potential to address clear needs in the clinical setting."

Bayer and Paratek signed a Collaborative Development and License Agreement in August 2003 for the development of the novel aminomethylcycline antibiotic BAY 73-7388/PTK 0796.