Issue Brief

Tracking the Pipeline of Antibiotics in Development

Drug-resistant bacteria, or superbugs, present a serious and worsening threat to human health. According to a Centers for Disease Control and Prevention report, 2 million Americans acquire serious infections caused by antibiotic-resistant bacteria each year, and 23,000 of them die as a result.1 Doctors routinely encounter patients with infections that do not respond to available treatment, and when new drugs come to market, bacteria quickly develop resistance. To ensure that the supply of new antibiotics keeps pace with these evolving pathogens, it is necessary to have a robust pipeline of new drugs and innovative pathways to get this medicine to the patients who need it most.

Developing new drugs involves a great deal of time, effort, scientific research, and expense. At best, only 1 out of 5 drugs that reach the initial phase of testing in humans will receive approval from the Food and Drug Administration for use.2 Development of antibiotics to treat highly resistant bacterial infections is especially challenging, because only a small number of patients contract such infections and meet the requirements to participate in traditional clinical trials.

To shed light on the antibiotic pipeline, evaluate public policies, and monitor the potential impact on public health, Pew has assessed antibiotics currently in clinical development. The list, which will be updated regularly, identifies each drug, its manufacturer, its potential targets, and its stage in the development process. (See methodology for the criteria used to select the drugs.)


The current assessment of the pipeline shows 36 new antibiotics in development. These drugs would potentially address many, but not all, resistant bacteria. However, given the inevitability that some in development will fail to win approval, it is clear that there are too few drugs in development to meet current and anticipated patient needs. As of March 2015:

  • Of the 36 antibiotics in development, eight were in phase 1 clinical trials, 20 in phase 2, and eight in phase 3. Historically, about 60 percent of drugs that enter phase 3 will be approved.(See the glossary of terms for descriptions of each phase.)
  • At least 11 of the antibiotics in development have the potential to treat infections caused by Gram-negative ESKAPE pathogens—a critical area of unmet need. Infections caused by these pathogens are not only difficult to treat, but finding new therapies to overcome Gram-negative resistance is also particularly challenging. Additionally, at least 16 of the antibiotics, if approved, could address infections caused by pathogens considered an “urgent threat” to public health by the Centers for Disease Control and Prevention. These include drug-resistant gonorrhea, Clostridium difficile infections, and carbapenem-resistant Enterobacteriaceae.

  • At least two antibiotics in early development attack bacteria in an entirely new way by sidestepping the resistance of some bacteria to available antibiotics. Other drugs in the pipeline attack the same targets in bacteria as available drugs but seek to thwart resistance by using new chemical compounds.
  • Of the 31 or so companies with antibiotics in clinical development today, only five rank among the top 50 pharmaceutical companies by sales. An additional large company, Novartis, currently has no drug in clinical testing but employs an active antibiotic research and development team. About three-quarters of the products currently in development are being studied by small companies rather than the large pharmaceutical firms that once dominated this field.4 Additionally, roughly 40 percent of the companies are considered pre-revenue, meaning that they have no products currently on the market.


The Pew Charitable Trusts and other organizations studying the issue of antibiotic resistance advocate for policies that address economic and regulatory hurdles to the development of new antibiotics. These efforts aim to keep the pipeline primed with a variety of potential treatments that have the best chance of making it to patients.

Pew supported approval of the Generating Antibiotic Incentives Now (GAIN) Act to stimulate development of new antibiotics. The law increased the commercial value of antibiotics intended for serious or life-threatening infections by extending the period during which the drugs can be sold without generic competition by five years. Drugs that benefit from GAIN are now in the antibiotic pipeline.

Additional legislative efforts to facilitate the development of antibiotics that address unmet medical needs are underway. Members have introduced bipartisan legislation in the House of Representatives and Senate to create this pathway: the Antibiotic Development to Advance Patient Treatment Act (ADAPT) Act
in the House and the Promise for Antibiotics and Therapeutics for Health (PATH) Act in the Senate.

A strong pipeline also requires focused efforts to boost basic scientific research and encourage cooperation between academia and industry. Pew is working with key stakeholders to identify ways to effectively address top scientific priorities for the discovery of new antibiotics.


An initial list of antibiotics in clinical development was provided by Citeline Inc.'s Pharmaprojects pipeline drug intelligence service.

The pipeline includes antibiotics intended to treat serious infections that act systemically, or throughout the body, but excludes locally acting drugs such as topical, ophthalmic, and inhaled products. It also does not include biological products, vaccines, new indications or different formulations for previously approved drugs, and drugs used to treat mycobacterial infections such as tuberculosis, Mycobacterium avium complex, Heliobactor pylori, and biothreat pathogens.

Also included in the pipeline are treatments for Clostridium difficile infections. Although many of these products act locally in the intestines, CDC considers this pathogen an urgent threat. While C. difficile infections are generally not resistant to the antibiotics used to treat them, there is a clear need for new products because they affect thousands of Americans each year and most of the infections result from antibiotic use.

Pew supplemented the data provided by Citeline with other public information—specifically, trials registered in, articles published in scientific literature or trade press, and company communications. Pew also works with an external expert to advise on certain determinations, such as the potential impact of drug candidates on resistant Gram-negative pathogens. This pipeline focuses on antibiotics under development for the U.S. market.

This pipeline will be updated bi-annually, beginning with the March 2015 update. To submit additions, updates, or comments, please contact Rachel Zetts at


  1. Centers for Disease Control and Prevention, Antibiotic Resistance Threats to the United States, 2013,
  2. Michael Hay et al., “Clinical Development Success Rates for Investigational Drugs,” Nature Biotechnology 32, (2014): 40–51.
  3. Ibid.
  4. Waseem Noor, "Pharm Exec's Pharma 50 2014," PharmExec, June 9, 2014,

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Linda Paris

Manager, Communications, Medical Programs