Given that chimpanzees are so closely related to humans and share similar behavioral traits, the National Institutes of Health should allow their use as subjects in biomedical research only under stringent conditions, including the absence of any other suitable model and inability to ethically perform the research on people, says a new report from the Institute of Medicine and National Research Council.
In addition, use of these animals should be permissible only if forgoing their use will prevent or significantly hinder advances necessary to prevent or treat life-threatening or debilitating conditions, said the committee that wrote the report. Based on these criteria, chimpanzees are not necessary for most biomedical research.
NIH also should limit the use of chimpanzees in behavioral research to studies that provide otherwise unattainable insights into normal and abnormal behavior, mental health, emotion, or cognition, the report says. NIH should require these studies to be performed only on acquiescent animals using techniques that are minimally invasive and are applied in a manner that minimizes pain and distress. Animals used in either biomedical or behavioral studies must be maintained in appropriate physical and social environments or in natural habitats, the report adds.
“The report’s recommendations answer the need for a uniform set of criteria for assessing the scientific necessity of chimpanzees in biomedical, comparative genomics, and behavioral research,” said committee chair Jeffrey Kahn, senior faculty member, Johns Hopkins Berman Institute of Bioethics, Baltimore. “The committee concluded that research use of animals that are so closely related to humans should not proceed unless it offers insights not possible with other animal models and unless it is of sufficient scientific or health value to offset the moral costs. We found very few cases that satisfy these criteria.”
Advances in the development of other research tools and methods, including cell-based tests and other animal models, have rendered chimpanzees largely nonessential as research subjects, the committee noted. It acknowledged two possible ongoing uses: the development of a limited number of monoclonal antibody therapies already in the pipeline, and development of a vaccine that would prevent infection by hepatitis C virus (HCV).
New methods such as recombinant technologies can replace the chimpanzee in efforts to develop monoclonal antibodies. While industry and academic laboratories are in the process of adopting these alternate approaches, there may be a few therapies in development that require continued use of chimpanzees to keep progress from stalling and slowing patients’ access to needed new treatments. These cases should be assessed to ensure that they meet the criteria outlined in this report, and NIH should continue to support the development of and access to alternatives to make future use of chimpanzees unnecessary.
The committee did not reach a consensus decision on whether chimpanzees are essential to the development of a prophylactic HCV vaccine and if or how much the use of chimpanzees would accelerate or improve this work. Roughly 3.2 million Americans are chronically infected with HCV, and about 17,000 new infections occur each year in the United States alone. Persistent infection can lead to liver disease and cancer; it is the most common cause of liver failure and transplantation in the United States.
Chimpanzees and humans are the only two species that are susceptible to HCV infection, and no other suitable animal models currently exist to test a prophylactic vaccine. However, chimpanzees’ immune systems clear HCV from their bodies more effectively, and they are less likely to develop liver damage. The committee members agreed that it would be possible and ethical to test a prophylactic vaccine candidate in humans without prior testing in chimpanzees, provided that it was first shown to be safe and to stimulate an immune response in other animals. However, the committee was evenly split on the necessity of testing various HCV vaccine candidates in chimpanzees before proceeding to human trials.
Research to develop a therapeutic HCV vaccine — one that would be given to people already infected with HCV to boost their immune systems’ ability to clear the virus — and antiviral drugs for patients with chronic HCV infection can be performed without use of chimpanzees, the committee agreed. These products can be more readily and rapidly tested in people, and new drugs and therapeutic vaccine candidates are moving forward without the use of chimpanzees.
The committee would not close the door on the possibility that chimpanzees may be needed in future research to develop treatments or preventive tools against as yet unknown diseases or disorders. It is impossible to say in advance whether other animal models or research tools will always serve effectively and quickly enough in the face of a novel health threat.
The report’s recommendations focus on the scientific necessity of the chimpanzee as a research subject, but also take ethical issues into account. Chimpanzees’ genetic closeness to humans and their similar biological and behavioral characteristics not only make chimpanzees a uniquely valuable species for certain types of research but also demand greater justification for conducting research with them, the committee said.
Notes about this animal research article
The study was mandated by Congress and sponsored by the National Institutes of Health. Established in 1970 under the charter of the National Academy of Sciences, the Institute of Medicine provides objective, evidence-based advice to policymakers, health professionals, the private sector, and the public. The Institute of Medicine, National Academy of Sciences, National Academy of Engineering, and National Research Council together make up the independent, nonprofit National Academies. For more information, visit National Academies or IOM.
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