Back to Anacor Homepage Developing Drug Candidates Through Boron Chemistry
Infinite Menus, Copyright 2006, OpenCube Inc. All Rights Reserved.
  Overview | Kerydin | Crisaborole | AN3365 | Animal Health | Neglected Diseases | Clinical Trials

We believe the unique characteristics of boron allow us to engineer novel product candidates that target a broad range of diseases and drive a rapid and efficient drug development process. Learn more about Kerydin
Learn more about AN2728

About Gram-Negative Infections  

AN3365 is our lead investigational antibiotic for the treatment of infections caused by Gram-negative bacteria. Gram-negative infections are a type of bacterial infection caused by a broad class of bacteria called Gram-negative bacteria and are most commonly acquired and treated in the hospital setting. Many commonly used antibiotics do not work against Gram-negative bacteria and resistance to existing therapies continues to be a growing problem.

Current Gram-Negative Therapies

Traditionally, Gram-negative infections have been treated with antibiotics, particularly beta-lactams, including penicillins, cephalosporins and carbapenems, and quinolones, including flouroquinolones. However, the effectiveness of existing antibiotics has been declining due to increasingly prevalent drug resistance. Bacteria develop resistance to drugs through genetic mutations or by acquiring genes from other bacteria that have become resistant. For example, in a recent survey of resistance rates of Gram-negative bacteria to current therapies in the United States, the resistance of E. coli to fluoroquinolones has been dramatically increasing. Resistance of E. coli to ciprofloxacin increased from 4% in 1999 to 30% in 2008 and resistance of E. coli to levofloxacin increased from 10% in 2003 to 30% in 2008. Over the same period, resistance of another Gram-negative bacteria, Klebsiella pneumoniae, to third generation cephalosporins, such as ceftriaxone and ceftazidime, increased from virtually no resistance to 15%. The same survey also showed that by 2008, 17%-19% of Pseudomonas aeruginosa were resistant to fluoroquinolones, 10%-70% were resistant to third generation cephalosporins and 7%-15% were resistant to carbapenems, such as meropenem and imipenem. Therefore, there is an ongoing need for novel antibiotics to combat the widespread proliferation of antibiotic resistance, particularly for Gram-negative bacteria. Also, currently approved antibiotics specifically targeting infections caused by Gram-negative bacteria are only available in either IV or oral formulations, but not both, so patients cannot continue on the same antibiotic therapy they received in the hospital once they are discharged.

Clinical Trials

In November 2009, we initiated a Phase 1 dose-escalating clinical study for AN3365, to evaluate the safety, tolerability and pharmacokinetics of AN3365 in healthy volunteers. The randomized, double-blind, placebo-controlled, dose-escalation study enrolled 72 subjects. Participants in this study received AN3365 in single or multiple doses for treatment durations of up to 14 days and included doses that achieve blood levels that are approximately four times the expected efficacious blood levels based on our preclinical studies. In June 2010, we reported positive Phase 1 results.

Following the completion of the Phase 1 trial, GSK exercised its option to obtain an exclusive license to develop and commercialize AN3365 and assumed responsibility for further development of the product candidate and any resulting commercialization.

In June 2011, GSK initiated two separate Phase 2b trials of AN3365 in complicated urinary tract infections (cUTI) and complicated intra-abdominal infections (cIAI).

In February 2012, GSK halted the clinical trials of AN3365 due to the identification of microbiological findings of resistance in a small number of patients in the Phase 2b trial for the treatment of cUTIs. From February through October 2012, GSK conducted additional pre- clinical research and, after assessing various options, elected to discontinue further development of AN3365 and return all rights to AN3365 to Anacor. Future development plans are currently under review.

Collaboration with GSK

For more information about our collaboration with GSK, please see our Strategic Alliances.