clinical trial

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TGN1412: Time to Change the Paradigm for the Testing of New Pharmaceuticals

Nirmala Bhogal and Robert Combes

Clinical studies in human volunteers are an essential part of drug development. These studies are designed to account for possible differences between the effects of pharmaceutical products in preclinical studies and in humans. However, the tragic outcome of the recent Phase 1 clinical trial on TGN1412 casts considerable doubt over the relevance of this traditional drug development paradigm to the testing of therapeutic agents for human use. The role of alternatives to animal testing is considered, and a series of recommendations are made, which could ensure that clinical trials are well informed and based on the
most relevant scientific information.
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Systematic Reviews of Animal Experiments Demonstrate Poor Human Clinical and Toxicological Utility

Andrew Knight

The assumption that animal models are reasonably predictive of human outcomes provides the basis for their widespread use in toxicity testing and in biomedical research aimed at developing cures for human diseases. To investigate the validity of this assumption, the comprehensive Scopus biomedical bibliographic databases were searched for published systematic reviews of the human clinical or toxicological utility of animal experiments. In 20 reviews in which clinical utility was examined, the authors concluded that animal models were either significantly useful in contributing to the development of clinical interventions, or were substantially consistent with clinical outcomes, in only two cases, one of which was contentious. These included reviews of the clinical utility of experiments expected by ethics committees to lead to medical advances, of highly-cited experiments published in major journals, and of chimpanzee experiments — those involving the species considered most likely to be predictive of human outcomes. Seven additional reviews failed to clearly demonstrate utility in predicting human toxicological outcomes, such as carcinogenicity and teratogenicity. Consequently, animal data may not generally be assumed to be substantially useful for these purposes. Possible causes include interspecies differences, the distortion of outcomes arising from experimental environments and protocols, and the poor methodological quality of many animal experiments, which was evident in at least 11 reviews. No reviews existed in which the majority of animal experiments were of good methodological quality. Whilst the effects of some of these problems might be minimised with concerted effort (given their widespread prevalence), the limitations resulting from interspecies differences are likely to be technically and theoretically impossible to overcome. Non-animal models are generally required to pass formal scientific validation prior to their regulatory acceptance. In contrast, animal models are simply assumed to be predictive of human outcomes. These results demonstrate the invalidity of such assumptions. The consistent application of formal validation studies to all test models is clearly warranted, regardless of their animal, non-animal, historical, contemporary or possible future status. Likely benefits would include, the greater selection of models truly predictive of human outcomes, increased safety of people exposed to chemicals that have passed toxicity tests, increased efficiency during the development of human pharmaceuticals and other therapeutic interventions, and decreased wastage of animal, personnel and financial resources. The poor human clinical and toxicological utility of most animal models for which data exists, in conjunction with their generally substantial animal welfare and economic costs, justify a ban on animal models lacking scientific data clearly establishing their human predictivity or utility.
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An Immunologic Model for Rapid Vaccine Assessment — A Clinical Trial in a Test Tube

Russell G. Higbee, Anthony M. Byers, Vipra Dhir, Donald Drake, Heather G. Fahlenkamp, Jyoti Gangur, Anatoly Kachurin, Olga Kachurina, Del Leistritz, Yifan Ma, Riyaz Mehta, Eric Mishkin, Janice Moser, Luis Mosquera, Mike Nguyen, Robert Parkhill, Santosh Pawar, Louis Poisson, Guzman Sanchez-Schmitz, Brian Schanen, Inderpal Singh, Haifeng Song, Tenekua Tapia,
William Warren and Vaughan Wittman

While the duration and size of human clinical trials may be difficult to reduce, there are several parameters in pre-clinical vaccine development that may be possible to further optimise. By increasing the accuracy of the models used for pre-clinical vaccine testing, it should be possible to increase the probability that any particular vaccine candidate will be successful in human trials. In addition, an improved model will allow the collection of increasingly more-informative data in pre-clinical tests, thus aiding the rational design and formulation of candidates entered into clinical evaluation. An acceleration and increase in sophistication of pre-clinical vaccine development will thus require the advent of more physiologically-accurate models of the human immune system, coupled with substantial advances in the mechanistic understanding of vaccine efficacy, achieved by using this model. We believe the best viable option available is to use human cells and/or tissues in a functional in vitro model of human physiology. Not only will this more accurately model human diseases, it will also eliminate any ethical, moral and scientific issues involved with use of live humans and animals. An in vitro model, termed “MIMIC” (Modular IMmune In vitro Construct), was designed and developed to reflect the human immune system in a well-based format. The MIMIC® System is a laboratory-based methodology that replicates the human immune system response. It is highly automated, and can be used to simulate a clinical trial for a diverse population, without putting human subjects at risk. The MIMIC System uses the circulating immune cells of individual donors to recapitulate each individual human immune response by maintaining the autonomy of the donor. Thus, an in vitro test system has been created that is functionally equivalent to the donor’s own immune system and is designed to respond in a similar manner to the in vivo response.
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