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Review of the Environmental Risks from Marketing GM Veterinary and Human Medicines

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Review of the Environmental Risks from Marketing GM Veterinary and Human Medicines Review of GMOs in medicines – final report Review of the environmental risks from marketing GM veterinary and human medicines Final report August 2008 Review of GMOs in medicines – final report EXECUTIVE SUMMARY Objectives and scope of this study 1.1 The purpose of this report is to review current and future applications of live genetically modified organisms (GMOs) in veterinary and human medicines, and provide an assessment of the potential risks of such applications to the environment and wider public health. The application of genetic modification (GM) technology in medicine is very diverse and increasing. The use of this technology encompases the growth of GM plants and microorganisms to produce compounds for use as medicines, as well as the use of live GM microorganisms as part of the medical treatments themselves. This report reviews this latter area of application, namely the use of live GMOs in medicines. Applications of live GMOs in medicines 1.2 Whilst the use of live GMOs in medicines is diverse, the applications have been categorised into four areas: gene therapy, vaccination, direct action, and drug delivery and probiotic-type treatments. However there is considerable overlap between these areas, with GMOs designed to offer roles in more than one area; these areas are defined below: ♦ Gene therapy – the transfer of genetic material into a cell nucleus, tissue, or whole organ, with the goal of curing a disease or at least improving the clinical status of a patient. Both GM bacteria and viruses have been developed as gene therapy vectors to deliver the genetic material for the treatment of cancers; cardiovascular, monogenic, infectious, neurological and ocular diseases; and deafness. GMOs offer new treatments on their own, or as complimentary therapies for existing conventional (non-GM) treatments such as chemotherapy or radiotherapy. ♦ Vaccination – the process of administering weakened or dead pathogens to a healthy person or animal, with the intent of conferring immunity against a targeted form of a related disease agent. Genetic modification is applied in this area in the attenuation of pathogens, and also in the development of new recombinant vaccines where an unrelated organism (typically non-pathogenic) is i Review of GMOs in medicines – final report modified to express the relevant antigens to induce immunity against a particular pathogen. ♦ Direct action – the term used in this report to describe treatments where the therapeutic effect is conferred through the replication and growth of the GMO. Whilst the GMOs used may also be modified to provide a gene therapy or drug delivery role, direct action refers essentially to the effects caused by the presence of the GMO at the target area. Examples include GM oncolytic viruses and anaerobic bacteria used to target cancer. The potential application of GM bacteriophages to target pathogenic bacteria has also been proposed. ♦ Drug delivery and probiotic-type treatments – the use of GM bacteria as drug delivery vectors to mucosal surfaces, especially the gastrointestinal (GI) and the female urogenital tracts. Whilst GMOs are currently not present in commercially available probiotic treatments, there are a number of developments reported involving the genetic modification of probiotic strains to target enteric pathogens and toxins. 1.3 Applications from all four areas have been evaluated in clinical trials (for use as human medicines) or field trials (for use in veterinary treatments), with some applications in later stage (Phase III) trials or commercial use. 1.4 The development and application of live GMOs in medicine is broadly the same for human and veterinary applications. Consequently the uses in these two areas have been considered together within each of the four groups of application. Differences in the use of a particular application, for example gene therapy is relatively uncommon in veterinary medicine, are a consequence of difference in demand because of cost or ethical considerations. There is little technical basis for these differences. 1.5 Most of the GMOs identified are either viruses or bacteria, although the genetic modification of the parasites Plasmodium sp. and Leishmania sp. (causative agents of malaria and leishmaniasis respectively) has been reported as part of the development of live attenuated vaccines against these two diseases. Potential risks posed to the environment and human health 1.6 The use of live GMOs in medicines poses a number of potential risks to the environment and human health. These risks are a consequence of the realisation of various hazards such as pathogenicity and the production of non-target effects. In considering the risks posed it is important to recognise that the presence of a live GMO in a medicine does not always pose a risk to the environment or human health per se , and will depend on the characteristics of the GMOs present, the intended application of the medicine and the effectiveness of any management strategies that ii Review of GMOs in medicines – final report are applied. A hazard such as the adverse response of the recipient to a gene therapy vector (vector-induced immune response) is for example equally relevant to GM and non-GM vectors as it is linked to the presence of the vector, rather than the expression of the transgenes. 1.7 Risks may be realised to both the immediate recipient of the GMO (i.e. the human or animal patient), and/or to the wider environment and general public. Whilst the purpose of the risk assessment in this report is the evaluation of the effects to the general public and the wider environment, the two areas are linked and cannot be considered in isolation. No significant adverse effects have been reported from the use of live GMOs in human and veterinary medicines to the general public and wider environment. This is a consequence of careful selection of the microorganism to be modified (for example the use of non-pathogenic strains) or design of the GMO (to ensure replication deficiency for example). Whilst some of the GMOs described have been found to be released from the patient into the wider environment, no subsequent adverse effects have been reported or are assessed as likely to occur. 1.8 The potential for the GMO to cause adverse effects is not desirable both in terms of compliance with the regulatory framework, and from a functional perspective as the effects will impair the action of the GMO. The potential for such effects is therefore expected to be avoided during the design and development of the GMO. All such GM-based medicines should therefore pose negligible risk to the environment and human health. Where particularly significant adverse effects from treatments involving GMOs have occurred, such as the onset of T cell leukaemia and a very small number of deaths, these have been to patients receiving the GMO and not to the general public or animals. 1.9 The level of risk posed by a GMO is affected by any containment or management strategies that are in place. With respect to GM viruses the most effective of these is ensuring that the virus is unable to replicate. This means that following administration to the patient, no further release and spread of the GM virus can occur. In this situation the risk to the wider environment and public health is restricted to a release of the GM virus pre-administration or exposure to contaminated materials such as needles or swabs. 1.10 In summary, the review of the uses of live GMOs in medicines has identified many applications in which GM technology has provided the means to develop treatments that would not be possible through conventional (non-GM) processes. These have highlighted the potential advantages offered by this technology and the role it can play in both the development of new medicines and to complement existing treatments. Whilst subject to a strong regulatory framework, genetic modification may also offer strategies to reduce the potential risks associated with the development and use of conventional medicines. A key feature of GM technology as iii Review of GMOs in medicines – final report the tool to alter a microorganism for use in medicines, compared to modifications achieved through non-GM processes, is that the resulting changes are more clearly defined and characterised. Whilst the ability of genetic modification to make very specific changes should increase regulatory confidence in the effectiveness and stability of the modification, unwanted non-target effects may still occur. The likelihood of such effects occurring can be minimised through correct selection and design of the GMO. Recommendation for further work 1.11 The one area identified as requiring further investigation is the effectiveness of auxotrophic modifications as a strategy for the biological containment of GM bacteria. These modifications are used in a number of the GM bacteria to limit or prevent the survival of the GM bacteria in the environment. Whilst laboratory studies show that auxotrophic modification is effective in controlling survival, quantitative information on survival of such GMOs in the environment is much more limited. This may be significant from a risk assessment perspective given the recent number of studies investigating the genetic modification of probiotic bacteria for use as treatments against enteric pathogens and diseases. Some auxotrophic modifications likely to be more suitable than others. iv Review of GMOs in medicines – final report EXECUTIVE SUMMARY I 1. INTRODUCTION 1 Content of the Report 1 2.
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