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Promoting the Development of Antibiotics and Ensuring Judicious Use in Humans


Statement of

Janet Woodcock, M.D.
Director, Center for Drug Evaluation and Research
Food and Drug Administration
Department of Health and Human Services

Before

the Subcommittee on Health
Committee on Energy and Commerce
U.S. House of Representatives

June 9, 2010

 

INTRODUCTION

Mr. Chairman and Members of the Committee, I am Dr. Janet Woodcock, Director of the Center for Drug Evaluation and Research (CDER) at the Food and Drug Administration (FDA or the Agency), which is a part of the Department of Health and Human Services (HHS).  Thank you for the opportunity to discuss FDA’s role in  ensuring the ongoing availability of safe and effective antimicrobial drugs.

Preserving the effectiveness of current antimicrobials and encouraging the continued development of new ones is vital to protecting human and animal health against infectious microbes.  A 2004 report from the Infectious Diseases Society of America (IDSA) noted that “[a]bout two million people acquire bacterial infections in U.S. hospitals each year, and 90,000 die as a result.  About 70 percent of those infections are resistant to at least one drug.”  And the problem is not limited to hospitals.  Clinicians practicing in every field of medicine, including veterinarians, encounter infections caused by resistant pathogens.  The impact of resistant infections on affected patients and families is significant and tragic.  As the IDSA also noted, “The trends toward increasing numbers of infection and increasing drug resistance show no sign of abating.  Resistant pathogens lead to higher health care costs because they often require more expensive drugs and extended hospital stays.”   

As a nation, we must address this problem from many sides; the development of new antimicrobial drugs is only part of the solution.  Microorganisms constantly evolve and are likely to grow resistant to any new drugs we develop.  This poses a continuous challenge and demands long-term solutions. We must be vigilant in protecting our vital antibiotic resources by reducing overuse and inappropriate use.  We must support innovative research in microbiology, epidemiology and regulatory science and conduct surveillance to detect the emergence of new resistant strains at the earliest possible moment.  Improved diagnostics will help curb overuse of antibiotics by allowing physicians to determine whether a patient has a bacterial infection and, if so, whether it is resistant to conventional antibiotics.  New vaccines have the potential to reduce the incidence of disease, diminishing the need for antimicrobial treatment in the first place.  

FDA is only one of many parties that need to be involved in a comprehensive solution.  The main role of FDA in addressing this problem is to establish clear, predictable regulatory pathways and to expeditiously review applications for new antimicrobial drugs, diagnostics, and vaccines.  FDA will continue to collaborate with our partners within the government, such as the Centers for Disease Control and Prevention (CDC), the U.S. Department of Agriculture (USDA), and the National Institutes of Health (NIH), and those outside the government.

In my testimony, I will provide background information on antimicrobials and antimicrobial resistance, and describe FDA’s participation in the U.S. Interagency Task Force on Antimicrobial Resistance and our efforts to facilitate the development of new antimicrobial drugs, diagnostics, and vaccines.

BACKGROUND   

Antimicrobial drugs are used to treat infections caused by microorganisms.  The term “antimicrobial” refers broadly to drugs with activity against a variety of microorganisms including bacteria, viruses, fungi, and parasites (such as malaria).  The term “antibacterial” refers to drugs with activity against bacteria in particular.  Another term commonly used to describe an antibacterial drug is “antibiotic.”  This term refers to a natural compound produced by a fungus or another microorganism that kills bacteria that cause disease in humans or animals.  Some antibacterial drugs are synthetic compounds; i.e., they are not produced by microorganisms. Though these do not meet the technical definition of antibiotics, they are referred to as antibiotics in common usage.

Antimicrobial resistance is the ability of bacteria or other microbes to evade the effects of a drug.  Many factors contribute to the spread of antimicrobial resistance.  In some cases, doctors prescribe antimicrobials too frequently or for infections against which they have no activity.  Sometimes patients do not complete the prescribed course of an antimicrobial, making it more likely that surviving microbes will develop resistance.  The use of subpotent or counterfeit antimicrobials also can contribute to resistance; counterfeit antimicrobials are a problem encountered particularly in the developing world.  The injudicious use of important antimicrobial drugs in both human medicine and animal agriculture is of particular concern.  Through international trade and travel, resistant microbes can spread quickly worldwide.  As of today, antimicrobial resistance mechanisms have been reported for all known antibacterial drugs that are currently available for clinical use in human and veterinary medicine.  In some cases, strains that are resistant to multiple antibacterial agents have been isolated.

Antimicrobial agents have been used in human and veterinary medicine for more than 70 years, with tremendous benefits to both human and animal health.  Many infections that were fatal, or left individuals with severe disabilities, are now treatable or preventable.  However, because bacteria are so adept at becoming resistant to antibacterial drugs, it is essential that such drugs be used judiciously to delay the development of resistance.     

U.S. Interagency Task Force on Antimicrobial Resistance

The U.S. Interagency Task Force on Antimicrobial Resistance (Task Force) was created in 1999 to develop a national plan to combat antimicrobial resistance.  FDA co-chairs the Task Force, along with the CDC and NIH.  

The Task Force also includes the Agency for Healthcare Research and Quality (AHRQ), Centers for Medicare & Medicaid Services (CMS), the Health Resources and Services Administration (HRSA), USDA, the Department of Defense, the Department of Veterans Affairs, and the Environmental Protection Agency.  In 2001, the U.S. Agency for International Development joined the Task Force to help address global antimicrobial resistance issues. 

In 2001, the Task Force published the “Public Health Action Plan to Combat Antimicrobial Resistance” (Public Health Action Plan or the Action Plan).  The Action Plan provides a blueprint for specific, coordinated federal actions to address the emerging threat of antimicrobial resistance.  It reflects a broad-based consensus of federal agencies, with input from consultants from state and local health agencies, universities, professional societies, pharmaceutical companies, healthcare delivery organizations, agricultural producers, consumer groups, and other members of the public.  The Action Plan has four major components:  surveillance, prevention and control, research, and product development.  The Interagency Task Force has been working on a revised Action Plan.  The revised Action Plan will provide more specific action items than the 2001 Action Plan and will include goal dates for completing many of the action items.

FACILITATING THE DEVELOPMENT OF NEW ANTIBACTERIAL PRODUCTS

No matter how assiduous our efforts to protect the effectiveness of existing antimicrobials, these drugs are likely to lose their effectiveness in the long run, and so new products must be developed.  We understand that the pharmaceutical industry values predictability and clarity.  FDA is working to provide scientifically sound guidance to industry on demonstrating the safety and effectiveness of new antibacterial drugs, particularly on indication-specific trial designs used to study a new drug.  This work is a very important part of the Commissioner’s Agency-wide regulatory science initiative.

The Challenges of Antimicrobial Development

The field of antibacterial drug development is currently facing challenges because of the lack of standardized data on the effect of treatment with antibacterial drugs in certain infections.  In addition, there are challenges because of the complexities in designing informative, ethical, and scientifically sound clinical trials for studying antibacterial drugs.

In part we are victims of the remarkable historical success of antimicrobials.  Because we have effective antibacterials, it is often unethical to compare a new candidate antibacterial to a placebo.  Thus we often recommend comparing a new (or investigational) drug to a standard approved drug.  But showing that an investigational drug performs about the same as a standard or control drug assumes that we know how the standard or control drug would perform in that trial.  For many currently used antibacterials, although we are confident that they are effective, we may only have limited information to characterize their precise effects.  Antibacterials initially became available during the 1930s and 1940s and they represented a tremendous advance in medicine.  They were soon adopted as the standard of care in the treatment of a variety of infectious diseases.  At that time, our methods for testing a drug’s effectiveness were much less sophisticated.  In some instances, antibacterial drug therapy was adopted as the standard of care without rigorous testing (for example, in a randomized, placebo-controlled trial) to assess the effect of antimicrobial drug therapy in a particular condition.  Because of this, in many instances there is a dearth of information to quantitatively assess the effects of new antibacterial drugs in certain infections.  

We also face other challenges in designing informative, ethical, and scientifically sound clinical trials for studying antibacterial drugs.  For example, it can be difficult to enroll a patient with a serious acute bacterial infection because he or she may not be able to wait to be enrolled in a clinical trial to begin treatment when therapy must be urgently initiated. At the same time, if the patient receives other antibacterial drug therapy before enrolling in a trial, this may cloud the assessment of the effect of the new drug; if the patient does well it may be difficult to know whether the effect was due to the antibacterial drug that the patient received before enrollment in the trial, the effect of the new drug, or the effect of both the prior therapy and the new drug.  In addition, at the time a patient is enrolled in a trial, the cause of the patient’s illness may not yet be established; results from culturing (growing) the bacteria may not be available at the time of enrollment.  These are just some of the challenges faced in designing a clinical trial for antibacterial drugs.

FDA Guidance on Developing Antibacterial Drugs

As we noted, the current situation is challenging because there are unresolved scientific issues regarding appropriate clinical trial designs.  FDA cannot overcome these scientific challenges alone, so we have been working to address these issues through guidance development, public workshops, and Advisory Committee meetings.  A number of parties have contributed to these efforts, including professional societies such as the IDSA and others, and scientists from academia, industry, and government.  Developing clear guidance will take some time, but the durability of our advice will depend upon the quality of the underlying science.

FDA has taken or is in the process of taking the following specific steps:

  • We have been actively working to gather scientific information to inform the development of recommendations on designing informative, ethical, and feasible clinical trials. 
  • We have issued draft guidance documents, posted on the FDA website, concerning clinical trial designs for studying antibacterial drugs.  These draft guidance documents cover various topics, including the following:
    • Non-inferiority clinical trial designs
    • Developing drugs for treating acute bacterial sinusitis
    • Developing drugs for treating acute bacterial otitis media
    • Developing drugs for treating acute bacterial exacerbation of chronic bronchitis in chronic obstructive pulmonary disease
    • Developing drugs for community-acquired bacterial pneumonia.

We are also working toward publishing additional draft guidance documents in the coming months for skin infections and hospital-acquired/ventilator-associated bacterial pneumonia.  As part of the process for developing these guidance documents, FDA held a November 18, 2008, Advisory Committee meeting to discuss clinical trial designs for skin infections and a public workshop on March 31, 2009, and April 1, 2009, co-sponsored with IDSA, the American Thoracic Society, the American College of Chest Physicians, and the Society of Critical Care Medicine on hospital-acquired/ventilator-associated bacterial pneumonia.  

From time to time FDA is asked whether groups outside of FDA can propose clinical trial designs that may include relatively unique or different strategies.  We welcome scientifically sound proposals from groups outside of FDA regarding appropriate trial designs.  FDA is always willing to consider other study designs, if such designs will provide an informative and ethical means to assess the safety and efficacy of a drug.  

Although the development of new antibacterial drugs is not the entire solution to the problem of antimicrobial resistance, it is a very important part of the solution to this important public health issue.  We need new therapeutic options to treat the resistant bacteria that we currently face and we will need new therapeutic options in the future.  FDA will continue to work with academia, industry, and others within the federal government to overcome the challenging scientific issues in this area.  However, the work on guidance development and clinical trial designs will not alone be sufficient to overcome the challenges facing the field of antibacterial drug development.  It will likely also take the development of incentives in order to stimulate the development of new antibacterial drugs so that we have new therapeutic options to treat the resistant pathogens that we currently face and the resistant pathogens that we will face in the years ahead.

Improving Diagnostics for Infectious Diseases

The development of new diagnostics can help combat antimicrobial resistance.  Diagnostics can reduce the use of antimicrobials because they can help a physician decide if it is appropriate to stop antimicrobial use and which antimicrobial drug(s) are likely to be effective for treating a given patient’s infection.

During the last three years, FDA has reviewed and cleared rapid tests for the detection of methicillin-resistant Staphylococcus aureus (MRSA) and identification of vancomycin-resistant enterococci (VRE) to aid in the prevention and control of MRSA infection or vancomycin-resistant infections in health care settings.  We have also been working closely with CDC, the Biomedical Advanced Research and Development Authority (BARDA), and NIH to determine how to best assess the performance of diagnostics for antiviral resistant strains of the 2009 H1N1 influenza virus.

We have participated or will participate in three public workshops between November 2009 and July 2010 to solicit input related to diagnostic devices and antimicrobial resistance.

  • On November 12-13, 2009, we co-sponsored a workshop along with IDSA entitled “FDA-IDSA Public Workshop: Advancing Clinical Development of Molecular and Other Diagnostic Tests for Respiratory Tract Infections.”  This workshop was aimed at determining the barriers preventing the development of rapid tests that could be used to distinguish viral from bacterial respiratory tract infections.
  • On June 7-8, 2010, we co-sponsored a workshop along with CDC and the National Institute of Allergy and Infectious Diseases (NIAID) within NIH that addressed 2009 Federal Tuberculosis Task Force recommendations regarding the development of new rapid methods for laboratory confirmation of tuberculosis and the identification of drug-resistant tuberculosis.
  • On July 26-27, 2010, we are co-sponsoring a workshop along with IDSA and NIAID entitled “Issues in Antibacterial Resistance and Device and Drug Development.”

FACILITATING THE DEVELOPMENT OF NEW VACCINES 

The development of new vaccines can also help combat antimicrobial resistance because the use of effective vaccines can reduce the need to use antimicrobials in the first place.  Prevention of infections through the use of vaccines has effectively eliminated or markedly decreased the problem of resistance in organisms such as Haemophilus influenzae type b (virtually eliminated in the United States while still a problem in other parts of the world) and Streptococcus pneumoniae, also known as pneumococcus.  FDA has also been very involved in facilitating the development of new vaccines to prevent diseases such as tuberculosis, malaria, and invasive Staphylococcus aureus infections.

We have taken the following specific actions to facilitate tuberculosis vaccine development:

  • Developed an assay to measure the potency and assess the safety of new tuberculosis vaccines
  • Characterized the safety and effectiveness of novel live attenuated tuberculosis vaccines
  • Evaluated certain T-cells as potential correlates of protective immunity against tuberculosis

We have also worked with the World Health Organization and the Aeras Global Tuberculosis Foundation on tuberculosis vaccine issues.

To facilitate malaria vaccine development, we have:

  • Developed a highly sensitive technique for measuring the number of malaria parasites in blood during vaccine studies
  • Developed a tuberculosis-malaria co-infection model for evaluating the safety and effectiveness of co-administration of tuberculosis and malaria vaccines
  • Identified excellent targets for genetic attenuation of a blood stage attenuated whole parasite vaccine

In addition to these specific actions related to development of vaccines for tuberculosis and malaria, we have also issued guidance, posted on the FDA website, concerning the development of vaccines to protect against global infectious diseases.

  

CONCLUSION

Antimicrobial resistance is a complex issue and addressing it will require creativity and persistence.  But the dangers of widespread antimicrobial resistance are so severe that we simply must rise to the challenge.  FDA will continue to work with federal, state, local, and foreign government officials, medical professionals, the regulated industry, and all of FDA’s stakeholders, in developing sound strategies to address and advance both human and animal health.  FDA looks forward to working with Congress on this important public health issue.

Thank you for the opportunity to testify today.  I welcome your ideas and your questions.