3.3.The scientific outlook for NHP replacement in the short, medium and long term with a view to establishing a specific phasing-out timetable
The scientific progress in the highly complex and interacting areas of basic and applied research, which use NHPs, is difficult to predict. Therefore, a specific timetable cannot be defined. Based on the presently available science, the total replacement of NHPs in many areas of use, either by other animal species or by non-animal methods, is unlikely to be achieved in the foreseeable future.
Due to our still limited understanding of pathophysiology and mechanisms of toxicity, an adequately justified need for the use NHPs as the best surrogate models for humans in specific parts of the safety testing for pharmaceuticals and monoclonal antibodies is very likely to remain for the foreseeable future. Use of alternative non-rodent species may only reduce the number of NHPs for testing, but increase the use of other species.
Regarding HIV research, it is possible that a genetically modified mouse strain with a human-like immunity, in which complete HIV replication can take place, may be available in the future. Still, one of the biggest hurdles is to know how the immune response in a mouse model will actually translate into the protection of humans, especially since correlates for effective protection against HIV infection in humans are not known. It is therefore necessary to continue the HIV vaccine development in NHPs in order to learn as much as possible about the immune response. Human vaccine clinical trials will deliver immunological and efficacy data that may reveal the relevance of the immunity and protection studied in the NHP models. Such information can then be utilised to develop better models with genetically modified mice and/or in vitro studies. However, a mouse model for HIV vaccine research cannot totally replace the use of NHPs. From a regulatory point of view, studies on the efficacy and safety of the candidate vaccine in a relevant surrogate species, such as NHPs, will remain necessary before starting clinical trials in humans.
Computer modelling and a wider use of modern imaging techniques such as MRI and PET may complement experimentation in NHP (see below). Because whole brain imaging technologies and invasive neurophysiological methods give qualitatively different information on brain function, those methods remain complementary and not alternatives. The future advancements in the development of non-invasive technologies will need to be regularly assessed.
The development of artificial organs and tissue engineering may replace or reduce the need for NHPs, but, currently, artificial organs are mostly extra-corporeal devices and are not an alternative to organ transplantation. Moreover, complex functions of organs such as the liver cannot yet be replicated artificially.