Novartis has gained exclusive worldwide rights to market PTK 0796, potentially the first once-daily broad-spectrum antibiotic that can be given by intravenous (IV) infusion or oral tablet to treat a wide variety of life-threatening infections, including those caused by highly resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and multi-drug resistant Streptococcus pneumoniae (MDRSP).

Under the agreement with Paratek Pharmaceuticals, a privately held company based in Boston, Massachusetts, the companies will share responsibility for developing PTK 0796. A phase-III study is already under way in complicated skin and skin structure infections (cSSSI), and clinical trials are planned in a number of other potential indications.

Because PTK 0796 may be given as a once-daily 30-minute IV infusion or daily oral tablet, it could offer patients a convenient way to continue antibiotic treatment after they have been discharged from hospital. Its broad spectrum of activity means it could be used as a single agent against a range of bacteria, unlike other antibiotics which may have to be used in combination.

"As the first in a new class of antibiotics, PTK 0796 is being developed to address the growing problem of bacterial resistance to currently available antibiotics," said Joe Jimenez, CEO of the Novartis Pharmaceuticals Division. "It will potentially benefit patients by offering a flexible and highly effective approach to the treatment of a number of critical infections, and should form an important addition to our growing portfolio of antibiotic medicines."

The in-licensing of PTK 0796 represents a further expansion of the Novartis infectious diseases portfolio following the acquisition of Protez Pharmaceuticals in June 2008. The Protez transaction covered the North American and European rights to PTZ601 (razupenem), currently in phase-II development as the first injectable broad-spectrum antibiotic in the carbapenem class to cover MRSA.
PTK 0796, a first-in-class aminomethylcycline, has shown broad-spectrum activity against a wide range of bacteria, including both Gram-positive and Gram-negative strains - a basic classification derived from the staining process used to analyze the cell wall - as well as atypical and anaerobic bacteria, which grow with little or no oxygen.

In addition, PTK 0796 has shown activity against multi-drug resistant bacteria such as MRSA, vancomycin-resistant enterococci (VRE) and Gram-negatives producing ESBL (extended-spectrum beta-lactamase). These bacteria have developed resistance during decades of antibiotic use, so many of the standard therapies are no longer effective. Studies have estimated there were nearly 100,000 deaths from hospital-acquired infections in the US in 2002[1], and around 50,000 deaths a year in the EU.

Clinical studies involving a total of more than 500 patients have shown that PTK 0796 has a favourable safety and tolerability profile. A phase-II study in cSSSI found that clinical success rates among evaluable patients (n=188) were 98 per cent for PTK 0796 and 93 per cent for linezolid (Zyvox). In this study PTK 0796 was used as a single agent, whereas Zyvox was used for Gram-positive infections only and an additional antibiotic had to be given for Gram-negative cases. The study met its primary safety and tolerability endpoints by showing no relevant difference between PTK 0796 and linezolid in terms of adverse events. In this study, approximately 50 per cent of the infecting bacteria were MRSA.

The Novartis portfolio of medicines for hospital-based infections includes Cubicin (daptomycin), marketed by Novartis in the EU and other countries for treating complicated skin and soft tissue infections (cSSTI), right-sided infective endocarditis (RIE) due to Staphylococcus aureus (S. aureus), and S. aureus bacteremia (SAB) when associated with RIE or cSSTI. Cubicin is the first of a new class of antibiotics called cyclic lipopeptides.

The agreement states that Novartis will make an upfront payment to Paratek in return for the exclusive rights to commercialize PTK 0796 worldwide. Both companies will share responsibility and costs for developing PTK 0796. Paratek will be eligible to receive future milestone payments, and will also receive a royalty on net sales of PTK 0796 around the world. Zyvox is a registered trademark of Pfizer.