There is no consistent definition of what encompasses a biological therapeutic, but most people working in this field consider biologics to include proteins (natural or recombinant), synthetic polypeptides, blood products, genetic compounds (oligonucleotides), and whole cells and tissues for transplantation. Vaccines are also classified as biological therapeutics, although many countries have placed vaccines under a separate set of guidelines and regulations. In Canada, compounds considered to be biological therapeutics (including vaccines) are listed within Schedule D of the Food and Drugs Act.
Challenges to Implementing the Three Rs
The development, manufacture, and quality control testing of biologics pose a number of unique challenges to implementation of the Three Rs. Quality control for biologics is often based on animal tests, rather than on chemical-based in vitro assays that are used to release small molecule drugs onto the market. The use of live organisms/cultures in the production of biologics introduces regulatory concerns related to batch-to-batch variability and the potential introduction of culture contaminants. Therefore, potency and safety testing are typically required for each individual batch of a biologic in order to maintain quality control. Regulatory authorities may also require re-testing of individual lots by government laboratories.
In addition, some older regulatory test methods use endpoints of severe clinical signs or lethality, or may specify the use of less refined or outdated procedures on animals (e.g., more invasive blood sampling procedures).
Since the development, manufacture and testing of biologics requires the use of large numbers of animals, which may experience significant pain and distress from this use, biologics have become a global focus for implementation of the Three Rs. For example, in the US, biologics testing has been identified by the Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) as one of their four highest priorities for the development of alternative methods. In Canada, CCAC policy requires that scientific use of animals should employ the most humane methods on the smallest number of appropriate animals required to obtain valid information. Therefore the re-evaluation and the development of newer methodologies for biologics that implement Three Rs alternatives is particularly important.
Three Rs Strategies for the Development of New Biologics
To assist in the implementation of the Three Rs in the development of new biologics, investigators/study directors should consider the following points:
- Most regulatory agencies consider each new submission of a biological therapeutic on a case-by-case basis. An understanding of the regulatory requirements could help to reduce the number of animals required for safety and efficacy studies, or whether such studies are in fact necessary.
- The development of alternative (non-animal) tests for early efficacy, potency and safety testing could help to reduce the number of animals that would later be required for quality control testing.
- Biological therapeutics frequently have species-specific activity. Those intended for use in humans may illicit little, or completely different, responses when tested in animal models. Therefore, in some cases animal tests may not be appropriate.
- The selection of appropriate models for the pharmacology and toxicity testing of biological therapeutics involves understanding of the biological therapeutic-target interaction. Data from comparative in vitro binding affinity and bioactivity (functionality) studies can help identify pharmacologically relevant animal species, and reduce the risk of generating misleading data.
- Pre-clinical safety testing of small molecule pharmaceuticals involves the establishment of a No Observed Adverse Effect Level (NOAEL) and/or other markers of toxicity to help determine a proper dosing range prior to administration to humans for the first time. However, for some biologics these end-points may be inappropriate or not possible to establish using animal models (e.g., no effect is seen in the animal model). Instead, a Minimum Anticipated Biological Effect Level (MABEL) may be a valid alternative in estimating the initial dose and exposure required.
Three Rs Strategies for the Manufacture and Testing of Existing Biologics
To assist in the implementation of the Three Rs in the manufacturing and testing of existing biologics, industry and government should consider:
- deleting obsolete or redundant tests (Replacement alternative)
- developing criteria to identify situations where animal tests are not required for new biologics (for example, when administrating a human protein to a person who is deficient in that protein) (Replacement alternative)
- revising wording in monographs to require use of non-animal alternative testing methods when available (Replacement alternative)
- developing and validating in vitro tests (Replacement alternative)
- minimizing or deleting requirements for regulatory re-testing by government laboratories (Reduction alternative)
- harmonizing tests and/or agreeing to mutual recognition of test data between different regulatory authorities (Reduction alternative)
- using one species in safety evaluation (Reduction alternative)
- combining potency and safety tests where possible (Reduction alternative)
- using statistical methods to determine the number of animals to use in a test (Reduction alternative)
- using serological techniques in which the presence of specific antibodies in the blood of immunized animals are used as a proxy to demonstrate protection against challenge by the relevant pathogen (Reduction and Refinement alternatives)
- using humane experimental endpoints (Refinement alternative)
- preparing and revising test methods to specify use of the most refined procedures on animals (e.g., the least painful methods of blood sampling and use of analgesics) (Refinement alternatives)
For more information on biologics and vaccines, the following resources may be useful.
- Hendriksen C. (2004) Reduction of numbers of animals used in the quality control of biologicals. ATLA 32(Suppl2):53-58.
- Hendriksen C. (2007) Three Rs achievements in vaccinology. ALTEX 14:575-579.
- Hendriksen C.F.M. (2006) Towards eliminating the use of animals for regulatory required vaccine quality control. ALTEX 23:187-190.
- Metz B., Hendriksen C.F.M., Jiskoot W. & Kersten G.F.A. (2002) Reduction of animal use in human vaccine quality control: opportunities and problems. Vaccine 20:2411-2430.
- Snoden D.F. & Ryle R.R. (2006) Understanding and applying regulatory guidance on the nonclinical development of biotechnology-derived pharmaceuticals. Biodrugs 20:25-52.
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