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Non-human primates in research and safety testing

1. Introduction – Overview of the use of primates in research and testing in the EU

    The SCHER opinion states:

    3. OPINION

    3.1.The areas of research (fundamental, translational and applied) and testing of products and devices in which non-human primates are used today

    3.1.1.Overview on the use of NHPs in research and testing

    Toxicity testing of pharmaceuticals in NHPs, under certain circumstances, represents an important part of the safety assessment of new low and high molecular weight pharmaceutical compounds and the use of NHPs in neurosciences and infectious disease research has generation important new insights into brain function and prevention of infectious diseases in humans. More than 100,000 non-human primates (NHPs) are used annually (Hau and Schapiro, 2006; Pieters, 2007) for biomedical research worldwide, with the USA, Japan and Europe as the main users. In 2005, the use of NHPs in the EU was 10,451 animals, representing 0.09% of the total (primate and non-primate) number of animals used (EC, 2007). Both the percentage and the absolute numbers have not substantially changed since 1999 (European Commission, 1999, 2003, 2005).

    Nearly 100% of New World (NW) primates (e.g. marmosets) used for experimentation are captive bred and have been for sometime, in some cases are at F 4/5 generation. However, for Old World (OW) primates, the figure is around 95% and most of these are F1s (i.e. the offspring between wild-caught captive F0; F2 are offspring of F1 x F1 - long term captive but both F1 and F2 can be considered to be ‘purpose bred’) * [*There is no definition of which generation (F1 or F2) is to be considered as ‘purpose bred’ in either Directive 86/609/EEC or in the EFSA report 2005, and much confusion has arisen because of this. Both F1 and F2 are not born or raised in the wild, but F1s have wild caught parents.]. The majority of these animals are not bred in the EU, but in China, Indonesia, Vietnam, Cambodia, the Philippines, and Mauritius. It is still common practice in some breeding establishments to replace breeding stock with wild-caught animals to avoid in-breeding, and one way to reduce this dependence on wild caught animals is to use the F1 generation for future breeding stock and not for research. Alternatively, to avoid inbreeding, breeding establishments could first consider an exchange of F0 males in a similar way to zoos. Regardless, it is likely to take a considerable time before sufficient F2 generation animals are available to meet research needs (EFSA 2005; FELASA, 2006).

    In regard to purpose breeding, there are several other aspects to be considered: The majority of the OW primates used for scientific procedures are still F1 generation animals, so that increasing the number of F1 animals available for breeding purposes could increase the number of wild-caught breeders needed to produce sufficient F1 animals both for scientific purposes and for breeding purposes for F2 animals for Europe during the transition time. In addition, experience of some of the breeders is that breeding from F1 and F2 generations has resulted in some unexpected difficulties not only because of in-breeding, which can be overcome, but also because of a decreased birth rate, poor mothering, a higher incidence of reduced birth weight, and diabetes in the off-spring (ILAR conference 2008). However, against this is the scientific value of using purpose-bred animals to produce accurate, reliable and reproducible data (EFSA 2005). If using non-purpose bred animal results to generate data these may be more variable or less robust than when using purpose bred animals (see EFSA 2005, Appendix A, ETS 123 Council of Europe, 2007).

    According to the information provided during a survey made by SCHER, wild-caught animals are rarely used in academia, but exceptions include research in aged animals and research in pregnant animals (breeding rate higher in wild-caught animals). Of the 72 academic institutions responding to the survey, only 4 used wild-caught animals. In addition, at only 6 sites the majority of the animals used were F1s. In the pharmaceutical industry (survey in 18 companies and 4 contract research organisations using NHPs), only two companies used wild-caught baboons or wild-caught Cynomolgus. For Cynomolgus, 18 of the 22 institutions used F1s and 9 institutions used 80 to 100% F2s. Of the 6 institutions using Rhesus, 3 used F1s. As outlined below, the majority of OW primates are used for applied research and safety testing, so that it has to be assumed that the majority are F1s. This further supports the assessment of EFSA that phasing out use of the F1 generation in the EU in research will take ‘considerable time’ (no time was specified), others suggested that it would be at least 15 years (FELASA, 2006).

    The European Commission regularly publishes the statistical data on the number of animals used for experimental and other scientific purposes in the EU (Report for the Council and the European Parliament in accordance with Article 26 of Directive 86/609/EEC). The ‘Fifth Report on the Statistics on the Number of Animals used for Experimental and other Scientific Purposes in the Member States of the European Union’ (EU, 2007) covers data collected in 25 Member States and gives an overview on the year 2005 with the exception of France who reported data from 2004. According to the Report, Great Apes were not used in experiments in the EU in 2005. Just for comparison to the 10,451 NHPs used in Europe, 54,998 NHPs were used in the USA in 2004. This number has fluctuated for years around 53,000, but after a sharp decline in 2001, the number of primates used in the US is again steadily increasing.

    However, comparing NHP use in 2002 and 2005 in the EU, the number of prosimians decreased by 38% while NW primates increased by 31% (Table 1). Member States reported that these changes were attributed to increases in the number of studies performed for pharmaceuticals and in toxicological safety testing, which are the main uses of NHPs (EC, 2007).

    [Table 1 - Changes in NHP use between 2002 and 2005 in the EU]

    The higher use of NHPs in some member states (see Table 2) is likely due to the presence of Contract Research Organisations (CROs) performing NHP testing. The number of animals used by a CRO is registered in the member state where the CRO is located, rather than in the country of the company requesting the studies.

    [Table 2 - NHP used in different EU countries]

    It is noteworthy that prosimians were only used in France, mainly for fundamental biology studies, and in Germany, where they were used almost exclusively for safety testing

    Origin

    It should be noted that in 2005, prosimians were, for the first time, all of EU origin. A similar trend is observed with the NW primates where an increasing number was either of EU or European Convention (ETS 123) origin (accounting for about 95%). Also, OW primates coming from the EU increased, but are still below 25%. It has also to be noted that OW primates are often re-used, mainly in R&D (Research and Development) and testing. According to EU statistics, 111 prosimians, 410 NW primates and 1,740 OW primates were re-used. As an example, in the Netherlands in 2004, 289 NHPs were used in 701 experiments; 403 of these Experiments involved the re-use of NHPs (Pieters, 2007).

    Species used

    All categories of NHP are used in biomedical experiments. The cynomolgus (Macaca fascicularis) and rhesus monkey (Macaca mulatta) are most frequently used. The cynomolgus tends to be the most widely used species, but rhesus is also used mainly because of available background data. NW primates, mainly marmosets (Callithrix jacchus), are sometimes said to be suitable, due to their small size, for testing products that are generally only available in limited amounts. However, thus far this is not confirmed in the dossiers provided to the regulatory authorities.

    Reasons for use

    The European Union distinguishes six categories of research areas were animal experiments may be conducted. These are present in the forms to be used by Member

    States (MS) to communicate data on use of experimental animals.

    The six categories defined for use of animals in experimental purposes in Europe are the following:

    1. Biological studies of a fundamental nature (2.2)
    2. Research, development and quality control of products (2.3) and devices for human medicine (2.3), dentistry (2.4) and for veterinary medicine (2.5)
    3. Toxicological and other safety evaluations, including safety evaluation of products (2.6)
    4. Diagnosis of disease (2.7)
    5. Education and training (2.8)
    6. Other (2.9)

    The distribution of NHP testing in relation to the different purposes, according to the six categories defined by the EU is reported in Table 3. No NHPs were used specifically for veterinary medicinal products (2.5). However, it should be realised that many veterinary medicinal products are the same as those developed for humans. The largest use is for ‘Toxicological and other safety evaluations, including safety evaluation of products’ (67% - mainly OW primates). When these data are analysed to identify the type of products tested in the safetyevaluationincluded within category 2.6,82% are products/substances/devices for human medicine and dentistry, being the rest used within the more unspecific category: other toxicological/safety evaluation (EC, 2007).

    [Table 3 - NHP used for different purposes (see above for description of categories)]

    Within the category ‘Toxicological and other safety evaluations, including safety evaluation of products’ (2.6), the number of NHPs used for safety testing for regulatory submissions is 6,992, representing almost 100% of the animals used in the category. In safety testing, 51% of the NHPs are used in sub-chronic and chronic toxicity studies and 34% for studies after a single administration to identify non-lethal clinical signs. A smaller percentage was used in ‘Developmental and reproductive toxicity’ (5.8%) and for other tests (7.9%). No studies were conducted where lethality was the primary endpoint. These percentages are more or less the same for all MS using NHP.

    In fundamental biology research, the use of NHPs is detailed in Table 4 .

    [Table 4 - NHPs used for different purposes in fundamental biology research]

    For the UK, statistics are available for 2007 (HO Stats, 2007). The number of procedures using NHP was 3,964, down by 240 (6%) from 2006, mainly due to a decrease in use of both OW and NW primates. Less than one percent of toxicological procedures performed used NHPs in 2007. Many primates were re-used since some of the procedures used on them had only a mild effect (such as taking blood samples).

    It is important to note that major investments to improve housing conditions for NHPs have been made over recent years with ‘enriched’ and social group housing.

    Based on response to a SCHER survey to pharmaceutical companies, experiments with substantial severity represent only a very small percentage (< 0.1 %) of NHP use.

    Source & ©: SCHER,  The need for non-human primates in biomedical research, production and testing of products and devices (2009),
    Section 3.1.1 Overview on the use of NHPs in research and testing, p. 7 -11.


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