Principles of WHO Guidelines on nonclinical evaluation of vaccines.

1. Principles of WHO Guidelines on nonclinical evaluation of vaccines. Jan Willem van der Laan Pharmacological-Toxicological Assessment Section Centre for Biological Medicines and Medical Technology National Institute for Public Health and the Environment, Bilthoven

2. OUTLINE • History • Regulatory documents • WHO Guideline on nonclinical evaluation of vaccines • Toxicity testing of GMOs

3. History • Animal experiments as batch release testing • Potency testing • Abnormal Toxicity • Sensitizing potential • Immunogenicity • Adjuvants: No separate issue • Aluminium hydroxide, • Aluminium phosphate

4. Regulational history • VACCINES under European legislation since 1993 • differentiation of pharmaceutical and non-clinical parts • overlap between potency testing and vaccine pharmacodynamics • direct pharmacological effects adrenergic receptors in autonomous nervous system, e.g. pertussis toxin, Heamophilus influenza, cholera toxin • overlap between batch release abnormal toxicity, non-clinical safety (in view of the developments in biotechnology) leading to • EU Guidance on Preclinical Pharmacological and Toxicological Testing of Vaccines CPMP/SWP/465/95

5. Other Non-clinical Guidance Documents • Guideline on Adjuvants in Human Vaccines CHMP/VEG/17/03, draft released for consultation, March 2004final to be expected January 2005 • WHO Guidelines on Nonclinical evaluation of vaccines, released November 2004

6. WHO Guidelines on Nonclinical Evaluation of vaccines • Nonclinical evaluation plays an essential part in the overall development of vaccine candidates • Product characterization • Proof of concept/immunogenicity • Safety testing in animals

7. Aims of Non-clinical Testing of Vaccines • Identify possible risks to the vaccinees • Help to plan protocols

8. Limitations of animal experiments • Pathogenesis and immune responses are frequently species-specific • Potential Safety concerns may not necessarily indicate a problem in humans

9. SCOPE of the WHO Guidelines • Vaccines are a heterogenous class of immmunogenic substances inducing specific active protective host immunity against infectious disease.

10. Vaccines • Inactivated Micro-organisms • Live Micro-organisms • Antigens extracted from micro-organisms • Chimeric micro-organisms • Antigens produced in vivo (DNA-vaccines)

11. Characterization of candicate vaccines • Vaccine production • Potency • Stability

12. Immunogenicity and other Pharmacodynamic studies • Proof of concept • Establish immunological characteristics • Help to select the doses and schedules Designed to assess relevant immune responses leading to protection

13. Antigen Specific adjuvant skin Antigen presenting cell Immune response is triggered T-Cells B-Cells, antibodies

14. Basic toxicity assessment • 4.1 General framework for designing pre-clinical toxicity of a vaccine (prior to initiation of clinical trials in humans) • 4.2 Additional considerations for specific toxicity assessments

15. Study design • Relevant animal species/strain • Dosing schedule • Route of administration • Method of vaccine administration (specific device?) • Timing of evaluation of endpoints

16. Animal species • Ideally, sensitive to the pathogenic organism • Develop an immune response to the vaccine antigen In general, one species is sufficient

17. Dose, schedule and route of administration • Dose maximizing exposure and peak antibody response • Vaccine should be given as episodic doses based on the kinetics of the antibody response • Clinical route of administration is preferred

18. Parameters monitored • In-life parameters • Daily observations • Weekly body weight and food consumption (1st week more frequent) • Interim analysis of heamatology and serum chemistry • Not only during treatment but also a few weeks after

19. Parameters monitored (2) At study termination: • Parameters mentioned • Immune response • Gross necropsy, tissue collection and preservation

20. Tissue list • Pivotal organs: brain, liver, kidney, reproductive organs, SoA. • Special attention to immune organs • Lymph nodes • Thymus • Spleen • Bone marrow • Peyer’s patches

21. Additional toxicity assessments Specific Immunologic Investigations • Precipitation of immune complexes • Humoral or cell-mediated immune response against self (molec. mimicry) • Exacerbation of the disease

22. Additional toxicity assessments (2) • Developmental toxicity studies • Usually not needed in case of paediatric vaccines • If WoCBP are included • Pre- and postnatal developmental study only

23. Additional toxicity assessments (3) • Developmental toxicity study design • premating treatment is recommended to assure maximal exposure • Number of doses depends on the response • Booster immunization may be necessary to expose the embryo to vaccine components

24. Safety pharmacology • If a vaccine (based on specific toxoids) is expected to affect physiological functions (CNS, respiratory, cardiovascular, renal) safety pharmacology studies should be performed

25. Pharmacokinetic studies • Determining serum concentration is normally not needed • Local deposition studies at the site of injection and the draining lymph node • Distribution studies in case of new formulations, adjuvants or route of administration

26. Special considerations • Adjuvants • Additives (excipients and preservatives) • Vaccine formation and delivery device

27. What about plant vaccines? • Oral administration • Immunogenicity? • Immunobioavailability • What are the risks? • Immunotolerance • hypersensitivity

28. What about plant vaccines? (2) • Plant constituents (alkaloids, proteins)? • Induces insertion pleiotrophic effects on plant toxoids?

29. GMO Legislation • GM Crops – is there a safety issue? Novel gene Novel protein Novel food/food ingredient Gene transfer Toxicity (animal tests) Allergenicity Substantial equivalence Toxicity (animal tests) Unintended effects Kleter and Kuiper (2002)

30. Safety assessment of GM foods • Molecular characterization • Changes in agronomical characteristics, morphology, and food composition • Toxicity of newly inserted proteins and of the whole food • Allergenicity • Gene transfer • Changed pattern in pesticide residues

31. Safety assessment of GM foods • Principle of “Substantial Equivalence” • Assessment in a comparative way, i.e. new crop vs. conventionally bred crop

32. Detection of unintended effects • Compared to convential crop based on phenotype based on: • Genomics - cDNA profile (microarray) • Proteomics – protein profile • Metabolomics – metabolite profile

33. Toxicity studies for GM food proteins • Acute oral toxicity – one high dose • Subchronic oral toxicity (28-90 days)

34. Allergenicity • Comparison by computer of structure with known allergens • Reactions of antisera of patients • Simulated digestion of novel proteins • Animal models, e.g. Brown-Norway rat (IgE-hyperresponsive)

35. Thank you