Pharmaceutical Toxicology in Practice E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 549

Veröffentlichungsjahr: 2011

Beschreibung

This book describes, with references to key source materials, the background to, and conduct of, the principal nonclinical studies that are central to drug development. The chapters provide an understanding of the key components of the preclinical phase of drug development with a hands-on description, with core chapters addressing study conduct, types, and reporting. As such, it is a practical guide through toxicology testing and an up-to-date reference on current issues, new developments, and future directions in toxicology. Opening with a practical description of toxicology and its role in the development of pharmaceuticals, the book proceeds to detail international regulations (including the impact of the new REACH standards for chemical safety), interdisciplinary interactions among scientists in drug development, steps in toxicity testing, and risk management. Further, the book covers the methods of genetic toxicology (assays, genomics, in vivo screening) as a complement to “traditional” toxicology in the risk assessment and risk management of pharmaceuticals.

Leseprobe

CONTENTS

COVER

HALF TITLE PAGE

TITLE PAGE

COPYRIGHT PAGE

CONTRIBUTORS

CHAPTER 1: INTRODUCTION

OBJECTIVES OF THIS BOOK

REFERENCES

CHAPTER 2: THE REGULATORY ENVIRONMENT

INTRODUCTION

THE INTERNATIONAL CONFERENCE ON HARMONIZATION

THE FUTURE OF ICH

OVERVIEW OF ICH GUIDELINES

DIFFERENCES BETWEEN GUIDELINES FOR NBEs AND NCEs

ONGOING REVISIONS TO ICH GUIDELINES

CONCLUSION

REFERENCES

CHAPTER 3: TOXICOLOGICAL DEVELOPMENT: ROLES AND RESPONSIBILITIES

INTRODUCTION

INSOURCING VERSUS OUTSOURCING

THE STUDY TEAM

ORGANIZATIONAL STRUCTURES

CONCLUSION

REFERENCES

CHAPTER 4: CONTRACT RESEARCH ORGANIZATIONS

INTRODUCTION

SELECTING A CONTRACT RESEARCH ORGANIZATION

ROLES AND RESPONSIBILITY

LABORATORY FACILITIES

QUALITY STANDARDS AND GLP COMPLIANCE

MONITORING STUDIES

PREPARING STUDY REPORTS AND REGULATORY DOCUMENTS

CONCLUSION

REFERENCES

CHAPTER 5: SAFETY PHARMACOLOGY

INTRODUCTION

REGULATORY ENVIRONMENT

EXPERIMENTAL MODELS

CORE BATTERY STUDIES

RESPIRATORY STUDY IN RODENTS

CENTRAL NERVOUS SYSTEM

FOLLOW-UP STUDIES

IN VIVO MODELS FOR CARDIOVASCULAR AND RESPIRATORY FINDINGS

CENTRAL NERVOUS SYSTEM FINDINGS

RENAL FINDINGS

GASTROINTESTINAL FINDINGS

CONCLUSION

REFERENCES

CHAPTER 6: FORMULATIONS, IMPURITIES, AND TOXICOKINETICS

INTRODUCTION

FORMULATION

LIQUID FORMULATIONS

IMPURITIES

REACTIVE METABOLITES

METAL AND SOLVENT RESIDUES IN THE TEST COMPOUND

TOXICOKINETICS

ANALYSIS OF BIOLOGICAL SAMPLES

INTERPRETATION OF TOXICOKINETIC DATA

CONCLUSION

REFERENCES

CHAPTER 7: GENERAL TOXICOLOGY

INTRODUCTION

TOXICOLOGY STRATEGY DEVELOPMENT

TOXICITY STUDIES NEEDED TO SUPPORT CLINICAL STUDIES

CONDUCT OF TOXICOLOGY STUDIES: OVERVIEW OF STUDY DESIGN

BLOOD SAMPLING

NECROPSY, TISSUE COLLECTION, AND HISTOPATHOLOGY

CONCLUSION

REFERENCES

CHAPTER 8: GENETIC TOXICOLOGY

INTRODUCTION

THE REGULATORY ENVIRONMENT

PROTOCOL DESIGN AND ASSAY CONDUCT

TESTING FOR A GENE MUTATION IN BACTERIA

IN VITRO METAPHASE CHROMOSOME ABERRATION TEST

IN VITRO MICRONUCLEUS TEST

IN VIVO RODENT MICRONUCLEUS TEST

IN VIVO RODENT CHROMOSOMAL ABERRATIONS TEST

APPROACHES TO EARLY GENOTOXICITY SCREENING

DATA INTERPRETATION AND EVALUATION OF RISK AND RELEVANCE TO HUMANS

ASSAYS USEFUL FOR FOLLOW-UP OF POSITIVE GENOTOXICITY FINDINGS

RISK–BENEFIT CONSIDERATIONS—SYNTHESIS OF THE DATA

REFERENCES

CHAPTER 9: DEVELOPMENTAL AND REPRODUCTIVE TOXICOLOGY

INTRODUCTION

REPRODUCTIVE TOXICITY

DEVELOPMENTAL TOXICOLOGY

REGULATORY GUIDELINES

PROTOCOL DESIGN AND ASSAY CONDUCT

JUVENILE TOXICITY STUDIES

DATA INTERPRETATION AND RISK EVALUATION

CONCLUSIONS

REFERENCES

CHAPTER 10: DATA ANALYSIS, REPORT WRITING, AND REGULATORY DOCUMENTATION

INTRODUCTION

DATA ANALYSIS AND INTERPRETATION

PEER REVIEW

REPORT PREPARATION

FORMAT OF THE REPORT

SUBSTANCE OF THE REPORT

RESULTS SECTION

DISCUSSION SECTION

SUMMARY SECTION

USING REFERENCES AND PUBLICLY ACCESSIBLE DATABASES

FDA DRUG APPROVAL PACKAGES

NATIONAL TECHNICAL INFORMATION SERVICE, U. S. DEPARTMENT OF COMMERCE

THE TOXICOLOGY AND ENVIRONMENTAL HEALTH INFORMATION PROGRAM (TEHIP)

HAZARDOUS SUBSTANCES DATA BANK

TOXLINE

NTP TECHNICAL REPORTS

IMPACT OF UNCLEAR REPORTING ON REGULATORY SUBMISSIONS

REFERENCES

CHAPTER 11: RISK MANAGEMENT

INTRODUCTION

RISK

THE RISK MANAGEMENT PROCESS

EFFECTIVE COMMUNICATION

COMMONLY USED RISK MANAGEMENT STRATEGIES

CONCLUSION

REFERENCES

INDEX

PHARMACEUTICAL TOXICOLOGY IN PRACTICE

Copyright © 2011 by John Wiley & Sons, Inc. All rights reserved.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey.Published simultaneously in Canada.

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CONTRIBUTORS

Claudio Arrigoni Accelera S.r.l. 20014 Nerviano (MI), Italy

Claudio Bernardi Accelera S.r.l. 20014 Nerviano (MI), Italy

Marco Brughera Accelera S.r.l. 20014 Nerviano (MI), Italy

Maurice G. Cary Pathology Experts LLC 4102 Binningen, Switzerland

Claude Charuel SARL CHARUEL 37270 St Martin le Beau, France

Franck Chuzel Galderma Research & Development, Snc. 06902, BP87, Sophia Antipolis Cedex, France

Alberto Lodola ToxAdvantage 37210 Noizay, France

Peggy Guzzie-Peck Johnson & Johnson Pharmaceutical Research and Development, LLC Raritan, NJ, 08869 USA

Valeria Perego Accelera S.r.l. 20014 Nerviano (MI), Italy

Bernard Ruty Galderma Research & Development, SNC. 06902, BP87, Sophia Antipolis Cedex, France

Jennifer C. Sasaki Johnson & Johnson Pharmaceutical Research and Development, LLC Raritan, NJ 08869 USA

Jeanne Stadler EURL Jeanne STADLER 37000 Tours, France

Sandy K. Weiner Johnson & Johnson Pharmaceutical Research and Development, LLC Raritan, NJ 08869 USA

Monique Y. Wells Toxicology/Pathology Services Inc. 75005 Paris, France

CHAPTER 1

INTRODUCTION

Alberto Lodola and Jeanne Stadler

Toxicology is defined variously as : “a science that deals with poisons and their effect” and “the scientific study of the characteristics and effects of poisons” [1, 2]. Rather dramatically, the emphasis is on “poisons”; a more inclusive definition of toxicology is, in our view, “the study of symptoms, mechanisms, treatments, and detection of poisoning, especially the poisoning of people.” Within this context, toxicology has a long, checkered history, which is described in an interactive online poster, which has been produced by Gilbert and Hayes [3]. This poster describes the principal milestones in the evolution of toxicology and effectively illustrates the point that, for many years, toxicology was indeed principally concerned with the use of and protection from, exposure to poisons. It was not until the sixteenth century that Paracelsus highlighted the link between poisons and “remedies” [3]. With the passage of time, this “preindustrial” view of toxicology gave way to the modern “postindustrial” era of toxicology. As a result, the toxicological sciences have matured and expanded to include a range of specific subdisciplines of toxicology as follows:

Clinical toxicology, the diagnosis and treatment of poisonings,Forensic toxicology, the use of analytical chemistry, pharmacology, and clinical chemistry to aid medicolegal investigation of death, poisoning, and drug use,Industrial or occupational toxicology, which deals with potential harmful effects of materials, products, and wastes on health and working environments,Environmental toxicology, the study of the potential effects upon organisms of the release of materials derived from human activities into the natural environment andPharmaceutical toxicology, the study of the potential effects on organisms of novel or established pharmaceuticals.

This book focuses on pharmaceutical toxicology and, in particular, nonclinical toxicology. Traditionally, nonclinical toxicology has had a bad image within pharmaceutical companies. This is often due to a poor understanding of the role of nonclinical toxicology in drug development. The regulatory guidelines that govern the design and conduct of toxicity studies still require, in most cases, that adverse events are produced in studies, or at a minimum, that very high doses (relative to clinical doses) be tested. As a result, toxicologists were/are seen as “drug killers,” or colleagues who conduct animal studies at unrealistically high doses of the test compound. In recent years, reforms within pharmaceutical companies, driven by changing scientific, regulatory, and economic environments, have meant that there is a greater interaction between different areas of a drug development organization. Consequently, there is increased understanding of the role of toxicology studies within drug development. Not only is toxicology, and the toxicological scientist, an integral part of the identification of drug candidates, structural optimization, and lead candidate selection, but it is a cornerstone of managing attrition. Yes, toxicology can “kill” a compound, but ideally, they will be compounds with unacceptable and/or unmanageable toxicities, and this attrition will occur as early in the development cycle as possible. This is good for the patient and is good economics. Nevertheless, on occasion, despite the best efforts of all those involved, a drug has to be withdrawn from use. Consider the case of Vioxx (rofecoxib), a COX-2 selective nonsteroidal anti-inflammatory drug (NSAID). This class of drugs was developed as a safer alternative to mixed COX-1/COX-2 NSAIDs such as aspirin, ibuprofen, and naproxen. It is now believed that all NSAIDs, when taken chronically, produced an increased risk of gastrointestinal bleeding and liver and kidney toxicity. In addition to problems typically associated with NSAIDs, several studies questioned the cardiovascular safety of Vioxx. In 2000, the Vioxx Gastrointestinal Outcomes Research (VIGOR) study, which compared Vioxx and naproxen, found that the risk of cardiovascular problems, including heart attack, chest pain, stroke, blood clots, and sudden death, was more than two times higher in the Vioxx group than in the control group and five times the risk of heart attack when compared to patients taking naproxen. Subsequently, the U.S. Food and Drug Administration (FDA), based on the analysis of the medical records of 1.4 million patients, suggested that Vioxx may have contributed to an additional 27,785 heart attacks or sudden cardiac deaths from 1999 to 2003. Because of these findings and data from additional studies, Vioxx was (voluntarily) withdrawn from the market by the manufacturer in 2004 [4]. It is worth noting that this withdrawal occurred despite the fact that many patients derived great benefit from this drug. Hopefully, in the future emerging technologies will help to target the use of drugs such as Vioxx at individual patients who have a maximal benefit/risk profile and in this way avoid the loss of valuable drugs to patients.

Traditionally, nonclinical–toxicological assessment has been based largely on data derived from animal studies; this has all the well-known advantages and inconveniences associated with the use of animals. There is increasing pressure to reduce, if not eliminate, the use of animals for scientific experiments and to reduce the cost and time taken to develop new drugs. Ideally, therefore, animal toxicity studies should be replaced by a series of robust, highly predictive, low-cost, and simple to conduct in vitro and in silico (computational) studies. Much progress has been made in recent years toward this goal; however, we are still a long way off from achieving this ideal. A range of in vitro studies, some of which are accepted by regulatory authorities, are now available to toxicologists; for example, the use of the 3T3 cell assay to test for phototoxicity potential [5]. In recent years, there have been great advances in decoding genes and DNA sequences from a number of organisms, a task that has been facilitated by the development of techniques such as microarrays [6, 7] and array-based comparative genomic hybridization [8, 9]. At present, one million sites in any individual’s genomic DNA can be simultaneously interrogated, which facilitates study of the link between disease and genetic variation. As a result, genomic data for humans is increasingly available and important in drug development. Increased understanding of the human genome provides insight into the underlying mechanism/s of disease, which in turn supports the development of new approaches to treating and/or preventing diseases [10-12]. To illustrate this link, it is necessary for us to briefly discuss the role of genes in human disease and the effects of xenobiotics on genes. Human diseases are monogenic, chromosomal, or multifactorial in origin: Monogenic diseases are caused by changes to a single gene [13, 14], chromosomal diseases are produced by changes in chromosomes [15], and multifactorial diseases are the most common and are caused by variation in many genes, and may be influenced by the environment. Genes are either constitutive or inducible. Constitutive genes are expressed continuously and control the ability of DNA to replicate, express, and repair itself, plus they control protein synthesis and are central to regulating metabolism. In contrast, inducible genes are only expressed intermittently [16]. During the process of gene expression, DNA is transcribed to mRNA, which in turn is translated to protein. Central to the regulation of gene expression is chromatin, a histone-DNA complex. For any given gene, the histone-DNA complex is the inactive state of the gene. One mechanism by which genes are silenced is linked to the presence of positively charged amino acids in histones, which produce zones in the histone–DNA complex that are susceptible to DNA methylation which then regulates gene expression [17, 18]. Small noncoding RNAs, for example, RNAi, may also be involved in the gene regulatory processes. This complex process requires the coordination of modifications to histones, transcription factor binding, and chromatin remodeling and results in the unwinding of the DNA in the transcription zone. As a result, the DNA is accessible to activating and repressor transcription factors (TFs), which bind to a specific DNA-binding domain and an effector domain. On binding an activating TF, the effector domain then recruits RNA polymerase II, allowing transcription of the corresponding gene/s to occur [19-21]. TFs can also activate genes by binding t the enhancer regions, which are located upstream, downstream, or in the introns of a gene. Small noncoding RNAs also involved in controlling gene expression. Because the regulation of genes involves the interaction of a number of different regulatory cascades, by interfering with these cascades xenobiotics can \alter gene expression and protein/enzyme production and, consequently, cellular metabolism. These effects can be monitored by analyzing tissue DNA/RNA profiles (transcriptomics), protein/enzyme production (proteomics), and metabolite production (metaboniomics) (see Fig. 1-1). Analysis of the “-omic” changes in different tissues, resulting from treating animals with a test compound may provide an early, specific indicator of toxicity [22, 23] and help to identify biomarkers of toxicity [24]. This approach has great promise for developing new, specific, sensitive techniques to better characterize, and understand, the nonclinical toxicity of drug development candidates and their risk–benefit ratio. Nevertheless, despite the great strides that have been made in developing and applying these new technologies, the backbone of nonclinical safety assessment remains animal toxicity studies for the time being.

Figure 1.1. The “omics” technologiesThe genome is comprised of all the genes, regulatory sequences and noncoding regions of an organisms DNA. The regulation of gene expression involves the interaction of a number of different regulatory cascades. By interfering with these cascades xenobiotics may alter gene expression, protein/enzyme production and in consequence cellular metabolism. These effects can be monitored by analysis of tissue DNA/RNA profile (Transcriptomics), protein/enzyme profiles (Proteomics) and metabolite production (Metaboniomics).

OBJECTIVES OF THIS BOOK

There is a wide range of excellent textbooks available, which review in detail individual and specialist aspects of pharmaceutical toxicology. Our focus is a more broad-based and general description of the subject. We describe, with references to key source materials, the background to, and conduct of, the principal nonclinical studies that are central to nonclinical drug development. Although the discussion is primarily based on a description of the development of the low-molecular-weight organic molecules, which have been traditionally developed as pharmaceuticals, the general process we describe is also applicable to newer drug technologies (proteins, nucleic acids, nanoparticles, and the like) linked to recent advances in biotechnology. As we emphasize in individual chapters, regardless of the source and type of test compound or route of administration, the basic toxicological questions to be asked are the same. What changes is the range of studies deployed to answer these questions. What are the relevant questions? They are questions that help:

the drug development scientist to understand the toxicological profile of the test compound,the drug discovery scientist to refine the chemical motif of the test compound to optimize efficacy and reduce side effects andthe drug development team to advance the test compound to the clinic and then to the marketplace and the patient.

In many instances, the understanding of a complex process, such as drug development, is helped by reviewing real-life cases. This presents a problem, as drug development is done case by case, but, as we show, a baseline approach is provided by regulatory guidelines. We encourage the reader to review the advice we give in this book in the light of the type of compound that they are developing and the drug development strategies deployed for drugs that are currently on the market. While our reference point is the role and conduct of nonclinical studies in the support of drug development, for the most part the subject matter we cover applies more broadly to the toxicological evaluation of chemicals. To illustrate this, we can consider the role of toxicology in the REACH (Regulation for Registration, Evaluation, Authorisation and Restriction of Chemicals) process, which was implemented in the European Union (EU) in 2007. The REACH legislation was enacted as a way of managing the risks that chemicals may pose to health and the environment. This legislation applies to chemicals used in industrial processes, cleaning products, paints, clothes, furniture, and electrical appliances (note that pharmaceuticals are not within REACH’s scope). In short, the use of all chemicals in the EU is covered by REACH [26]. In order to meet their legal obligations under REACH, manufacturers and importers of chemicals must identify and manage risks linked to the substances they manufacture and market. To do this, they submit a Registration Dossier to the European Chemicals Agency [27]. One element of this dossier is a Chemical Safety Report (CSR), which describes the chemical safety assessment for the chemical under consideration. In the CSR, registrants must present and discuss a range of data [28]:

substance identityphysicochemical propertiesexposure/uses/occurrence and applicationsmammalian toxicitytoxicokineticschemical categoriesecotoxicityenvironmental fate, including chemical and biotic degradation

As this list shows, some data (items highlighted in italics) are similar to the nonclinical data required in drug development. Indeed, if it is available, nonclinical toxicity data can be used. Thus, Chapters 4–10 in this book, which deal with study conduct, types of study, and reporting, also apply to generating toxicity data for the CSR. However, remember that the underlying philosophy differs and thus will alter the risk assessment process relative to pharmaceuticals. In Chapter 11, we discuss the risk management of potential drug toxicities in humans. Again, the general principles that we discuss apply to the REACH risk management process, with the added complication that REACH also requires the preparation of an environmental risk management plan, which falls outside the scope of this book. Our attention is mostly on the “scientific” aspects of nonclinical toxicology. However, Chapters 3 and 4, and, to some extent, Chapter 10, deal with administrative/organizational aspects of nonclinical studies. These activities are sometimes overlooked, or relegated to a secondary importance; this is a mistake. Time spent optimizing these aspects of nonclinical activities can produce significant savings in terms of time and resources and reduces the possibility of errors in study conduct, data interpretation, data reporting, and risk management.

REFERENCES

1. Merriam-Webster’s On-Line Dictionary, 2009. http://www.merriam-webster.com/

2. Cambridge Advanced Learner’s Dictionary, 2009. http://dictionary.cambridge.org/

3. Gilbert SG and Hayes A, 2005. Milestones of Toxicology. http://toxipedia.org/wiki/display/toxipedia/History+of+Toxicology

4. Anon, 2009. Vioxx News at http://www.vioxxnews.com/

5. Europe, the Middle East, and Africa, EMEA, 2002. Note for guidance on phototoxicity testing. http://www.emea.europa.eu/pdfs/human/swp/039801en.pdf

6. Hon GC, and Hawkins RD, Ren B, 2009. Predictive chromatin signatures in the mammalian genome. Hum Mol Genet18:R195–R201

7. Morozova O, Hirst M and Marra MA, 2009. Applications of new sequencing technologies for transcriptome analysis. Annu Rev Genomics Hum Genet10:135–151

8. Wu X and Xiao H, 2009. Progress in the detection of human genome structural variations. Sci China C Life Sci52:560–567

9. Waddell N, 2008. Microarray-based DNA profiling to study genomic aberrations. IUBMB Life60:437–440

10. Chen X, Jorgenson E, and Cheung ST, 2009. New tools for functional genomic analysis. Drug Discov Today14:754–60

11. Ioerger TR and Sacchettini JC, 2009. Structural genomics approach to drug discovery for Mycobacterium tuberculosis. Curr Opin Microbiol12:318–25

12. Plump AS and Lum PY, 2009. Genomics and cardiovascular drug development. J Am Coll Cardiol53:1089–1100

13. de Vries B, Frants RR, Ferrari MD and van Den Maagdenberg AM, 2009. Molecular genetics of migraine. Hum Genet126:115–32

14. Gasser T, 2009. Molecular pathogenesis of Parkinson disease: Insights from genetic studies. Expert Rev Mol Med11:e22

15. Kalman B and Vitale E, 2009. Structural chromosomal variations in neurological diseases. Neurologist15:245–53

16. Latchman DS, 2007. Gene Regulation. New York: Taylor & Francis

17. Spannhoff A, Hauser AT, Heinke R et al., 2009. The emerging therapeutic potential of histone methyltransferase and demethylase inhibitors. ChemMedChem4:1568–1582

18. Shukla A, Chaurasia P, Bhaumik SR, 2009. Histone methylation and ubiquitination with their cross-talk and roles in gene expression and stability. Cell Mol Life Sci66:1419–1433.

19. Roeder RG, 1996. The role of general initiation factors in transcription by RNA polymerase II Trends Biochem Sci21:327–335

20. Nikolov DB and Burley SK, 1997. RNA polymerase II transcription initiation: A structural view. Proc Natl Acad Sci USA94:15–22

21. Lee TI and Young RA, 2000. Transcription of eukaryotic protein-coding genes. Annu Rev Genet34:77–137

22. Xu EY, Schaefer WH, and Xu Q, 2009. Metabolomics in pharmaceutical research and development: Metabolites, mechanisms and pathways. Curr Opin Drug Discov Devel12:40–52

23. Schiess R, Wollscheid B, and Aebersold R, 2009. Targeted proteomic strategy for clinical biomarker discovery. Mol Oncol3:33–44

24. Lord PG, Nie A, and McMillian M, 2006. Application of genomics in preclinical drug safety evaluation. Basic Clin Pharmacol Toxicol98:537–546.

25. Waring JF and Halbert DN, 2002. The promise of toxicogenomics. Curr Opin Mol Ther4:229–235.

26. European Chemicals Agency, 2009. REACXH and CLP guidance at http://guidance.echa.europa.eu/index_en.htm

27. European Chemicals Agency, 2009b. at http://echa.europa.eu/home_en.asp

28. European Chemicals Agency, 2008. Guidance on information requirements and chemical safety assessment. Part B: Hazard assessment at http://guidance.echa.europa.eu/docs/guidance_document/information_requirements_part_b_en.pdf?vers=20_10_08

CHAPTER 2

THE REGULATORY ENVIRONMENT

Claudio Bernardi and Marco Brughera

INTRODUCTION

More than 400 years ago, Paracelsus (1493–1541), one of the “fathers” of the biomedical sciences, toxicology in particular,,pointed out that “all substances are poisons, and it is the right dose that differentiates a poison from a remedy.” This assumption generally applies to natural compounds such as animal venoms and poisonous plants and to chemically or biologically derived pharmaceuticals. Subsequently, in the eighteenth and nineteenthcenturies, the “art of toxicology” was further developed by a number of scientists (M.J. Bonaventura Orfila, Claude Bernard, Louis Lewin), who are now considered the founders of modern toxicology, resulting in 1893 in the publication by Rudolf Kobert (1854–1918) of one of the first textbooks on modern toxicology [1]. However, during this time scientists investigating the mechanisms of toxicity and attempting to define rational criteria for the detection of the toxic effects of xenobiotics, used different investigative approaches, which sometimes produced conflicting and misleading results. In more recent times, when this largely academic interest in toxicology was coupled with the more pragmatic interests of the nascent pharmaceutical industry, toxicology was “standardized” and given a legal dimension. This resulted in the appearance of regulatory authorities, which have oversight of the regulatory framework for drug development and the granting of marketing approval. In short, “regulatory toxicology” was born. As a result, regulatory authorities started to define the range of experimental data that pharmaceutical companies needed to support the conduct of clinical trials in humans with drugs in development and to obtain the authority to market new drugs.

The evaluation of experimental data for novel drugs, by an independent regulatory authority, was implemented at different times in different regions. One of the first regulatory authorities to be established was the US Food and Drug Administration (FDA), and was a result of the the Elixir Sulfanilamide disaster [2]. In 1932, it was shown that a chemical derivative of the red dye, Prontosil, had antibacterial properties and when treated with this modified dye, patients who were severely ill from a streptococcal infection made a complete recovery. Subsequently, other researchers developed modified Prontosil compounds, which eventually lead to the discovery of the so called “sulfonamide drugs.” Sulfanilamide, used safely in tablet and powder form since 1936, was the first member of the sulfonamide family of drugs that are used today. In 1937, a liquid form of the drug (Elixir Sulfanilamide), using diethylene glycol to dissolve the sulfanilamide, was commercialized in the United States. In the absence of any legal requirement to do so, no additional nonclinical testing of this novel formulation was conducted, and in spite of the known toxic properties of diethylene glycol, Elixir Sulfanilamide was used to treat patients. From September to October 1937, more than 100 people died as a direct consequence of treatment with Elixir Sulfanilamide. This tragedy could have been avoided if a few, relatively simple, toxicity studies had been conducted with the reformulated drug. Japanese regulatory authorities were formed in the 1950s and in many European countries in the 1960s, following the thalidomide tragedy [3]. Thalidomide first entered the German market in 1957 as an over-the-counter remedy; the product was regarded as “completely safe” “even during pregnancy.” From 1957 to 1961, thalidomide was marketed in about 50 countries and was used to treat pregnant women against morning sickness and stress, and to help them sleep. Thalidomide does not have any acute toxicity; a fatal overdose is virtually impossible, and peripheral neuropathy is probably its dose-limiting factor. However, although some studies have shown a dose dependence of peripheral neuropathy, typically after a dose of 40–50 g, in other studies neuropathy only occurred at a dose of just 3–6 g. In 1956, to an employee of the drug’s manufacturer (Chemie Grunenthal) had given his wife samples of the drug, and she gave birth to a baby born with malformations. Soon thereafter, there were additional reports of malformed children born to mothers treated with thalidomide, and a common pattern of limb deformities (principally phocomelia) emerged. In all, from 1956 to 1962, about 10,000 children were born with severe malformations to mothers who had been treated with thalidomide. Dr. W.G. McBride, at Crown Street Women’s Hospital, Sydney, Australia, first raised suspicions of the link between thalidomide use in pregnant women and malformations. The drug was withdrawn from the market in 1961. Consequently, there was a rapid increase in the laws, regulations, and guidelines for reporting and evaluating the safety, quality, and efficacy data of new drugs. Against this background of national and/or regional regulatory authorities having responsibility for developing the requirements for drug registration, differences in regulatory requirements emerged; this came at a time when the pharmaceutical industry was becoming internationally orientated and was developing global marketing strategies. Indeed, the requirements for quality, safety, and efficacy data were so divergent between (national) regulatory authorities that the pharmaceutical industry sometimes had to repeat time-consuming and expensive studies to market the same drug in different countries. Given government concerns over rising health care costs, the pharmaceutical industry’s concern over the escalating cost of research and development and the public’s expectation of rapid access to safe, efficacious new medicines, it became apparent that there was a need to rationalize and harmonize these regulations.

THE INTERNATIONAL CONFERENCE ON HARMONIZATION

To address issues of national divergence in regulatory requirements for pharmaceutical development, the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) was established in 1990. In brief, the purpose of ICH [4] is to:

provide a forum for regulatory authorities and the pharmaceutical industry to discuss the requirements for drug development,update harmonized technical requirements in the light of advances in science and technology,ensure that there is a harmonized approach to the development of new guidelines/requirements,facilitate the adoption of new or improved research and development approaches, andfacilitate the dissemination of harmonized guidelines and encourage common standards.

The ICH process was launched by representatives of regulatory agencies and industry associations of Europe, Japan, and the United States. The ICH Steering Committee (SC) was established to oversee the process in which expert working groups (EWGs) would engage the scientific and technical aspects of each harmonization topic. The first SC meeting decided that safety, quality, and efficacy would be the focus for the initial harmonization activity.

Key Players in the ICH Process

Key players in the ICH process are the six parties drawn from regulatory bodies and pharmaceutical companies in Europe, Japan, and the United States:

European Commission (EC),European Federation of Pharmaceutical Industries and Associations (EFPIA),Japanese Ministry of Health, Labour and Welfare (MHLW),Japan Pharmaceutical Manufacturers Association (JPMA),United States Food and Drug Administration (FDA) andPharmaceutical Research and Manufacturers of America (PhRMA).

The EC, which represents 27 members of the nations of the European Union (EU), established the European Medicines Agency (EMEA) as the centralized regulatory authority for the EU. The EMEA is responsible for drug marketing applications and approvals using the so-called “centralized procedure” [5]. Technical and scientific support for ICH activities is provided to the EMEA by the Committee for Medicinal Products for Human Use (CHMP). The EFPIA includes members from 29 national pharmaceutical industry associations and 45 leading international pharmaceutical companies [6]. Much of the federation’s work is concerned with the activities of the EC and the EMEA; a network of experts and country coordinators had been established to ensure that harmonized EFPIA views are heard within the ICH process.

Although the Japanese MHLW has responsibility for approving drugs, medical devices, and cosmetics [7], technical and scientific support for ICH activities are provided by the Pharmaceuticals and Medical Devices Agency (PMDA), the National Institute of Health Sciences (NIHS), and experts from academia. JPMA represents all the major research-based pharmaceutical manufacturers in Japan.

The FDA has a wide range of responsibilities for drugs, biologicals, medical devices, cosmetics, and radiological products [8]. The FDA consists of administrative, scientific, and regulatory staff organized under the Office of the Commissioner and has several centers with responsibility for the various products that are regulated. Technical advice and experts for ICH work are drawn from the Centre for Drug Evaluation and Research (CDER) and the Centre for Biologics Evaluation and Research (CBER). PhRMA represents US pharmaceutical companies and companies that conduct biological research related to the development of drugs and vaccines [9] and coordinates its technical input to ICH through dedicated committees of experts drawn from PhRMA member companies. In addition to the key players, there are a number of participants who have observer nonvoting status and provide a link between the ICH and non–ICH countries and regions:

the World Health Organization (WHO),the European Free Trade Association (EFTA), andCanada (represented by Health Canada).

Additionally the International Federation of Pharmaceutical Manufacturers & Associations (IFPMA), a nongovernmental organization representing national industry associations and companies from both developed and developing countries, is closely associated with ICH and ensures contact with the pharmaceutical industry from outside ICH Regions.

The ICH Process

The ICH process is described in detailed elsewhere [4]. Following is a summary based on this detailed description. New harmonization initiatives arise from:

ICH regional guideline workshops,regional and international conferences, workshops, and symposia, andAssociations, federations, and societies linked to pharmaceutical development.

Once a proposal for harmonization has been made by one of the six parties (see above) to ICH or one of the ICH observers, the SC formally initiates the harmonization process. A concept paper (CP) summarizing the proposal is then prepared and includes at least the following information:

proposed harmonization action,description of the problem,summary of the technical/scientific issues, which require harmonization,origin of the proposal, andtype of working group that will take the proposal forward.

If the proposal is taken forward, a business plan must also be agreed on. An EWG or an IWG (Implementation Working Group) is then formed, on which the six ICH parties each have a representatives, and a topic leader and deputy topic leader are nominated. In addition, ICH Observers and interested parties may nominate representatives to the working group. A rapporteur is appointed who is responsible for keeping an up-to-date action plan and timetable with clear deliverables and deadlines. In moving from topic proposal to adoption, there are a number of steps involved:

Step 1 The rapporteur prepares an initial draft guideline based on the original CP. These drafts (and revisions) are reviewed by the EWG, and when a consensus is reached, the process moves to the next stage.

Step 2 If there is consensus within the SC, the Step 1 guideline is released as the Step 2 final document. If consensus is not reached within an agreed period, the SC either extends the timetable for discussion or suspends/abandons the project.

Step 3 The Step 2 final document enters Step 3, at which time there is a wide-ranging regulatory consultation in the three regions. In the EU Step 2 is published as a draft CHMP Guideline; in Japan it is (translated) issued by the MHLW for internal and external consultation; and in the United States it is published as draft guidance in the Federal Register. Industry associations and regulatory authorities in non–ICH regions also comment at this time. The outcome of this consultation procedure is the Step 4 expert Document. If consensus is not achieved in previous steps, the SC may extend the period for discussion, abandon the current draft and move the project back to Step 1, or suspend/abandon the project.

Step 4 The proposed guideline is then recommended for adoption. If, however, there are major objections from one or more parties representing industry, the regulatory parties may agree to prepare a revised document.

Step 5 This is the regulatory implementation step, is in accordance with national/regional procedures, and results in the adoption of the guideline within the (legal) regulatory framework of the EU, Japan, and the United States.

This procedure adopting new or revised guidelines can lead to uncertainty as to when published drafts and/or revisions should be adopted into drug development strategies. When existing guidelines undergo revision, it is important for users to engage with regulatory authorities (e.g., in pre-Investigational New Drug (IND) or end-of phase 2 meeting) to discuss development strategies. In general, however, waiting until Step 4 before adopting draft guidelines or revisions is commonly considered a prudent approach. It is unlikely, however, that major changes are implemented after Step 3, and generally only fine tuning occurs at these stages. Moreover, for new guidelines, the potential advantages of following preliminary recommendations may outweigh the risks of delays in the development program once the guideline enters Step 5.

THE FUTURE OF ICH

Since ICH was formed, there have been six conferences (1991, 1993, 1995, 1997, 2000, and 2003) and three public meetings (2007, 2008, and 2009) to ensure that the harmonization process is carried out in a transparent manner and that there is an open forum in which to present and discuss ICH recommendations. In general, the most significant topics addressed and followed-up outcomes from these meetings were identifying new harmonization initiatives and needs for further international harmonization, implementing the Common Technical Document (CTD), selecting new topics in a systematic manner with a focus on new technologies and innovative medicines, and considering the need for increased regulatory cooperation postmarketing. As a result, the following projects were adopted:

to revise the M3 Guideline to reduce the use of experimental animals, in the light of alternative methods for safety evaluation, the possibility of combining juvenile toxicity studies with chronic toxicity studies, and the revision of animal studies required in support to early clinical studies (i.e., microdosing),to revise the S6 Guideline to address species selection, study design, reproductive/developmental toxicity, carcinogenicity, and immunogenicity,to define the scope of the S9 Guideline for patient selection in studies with anticancer compounds and to review the requirements for obtaining a marketing authorization, andto revise the S2 guideline in the light of recent advances in understanding of the genotoxicity and potential carcinogenicity of xenobiotics.

Currently, several guidelines are under revision, having recently reached Steps 2–4. Taking into account the average time required to reach Step 5, we can assume that it will take at least one or two years before all the guidelines under revision are adopted worldwide. In addition, discussion has started within the ICH program to identify potential new issues that need to be addressed in the near future. Several topics have already been identified (i.e., photosafety, identification and use of safety biomarkers in the preclinical studies, new cell-based therapies, and the like); additional topics will certainly be identified in the future. Sometimes, unexpectedly or following the review of a controversial dossier, regulatory authorities focus their attention on specific findings or topics. Often this focus is limited to a particular region or national authority, and the issue raised does not assume international relevance. Recent examples of this are:

the potential risk for arrhythmias due to drug-induced QT prolongation generated much scientific debate and resulted in the release of nonclinical and clinical guidelines. Despite numerous retrospective evaluations, the development of new predictive tools and methodologies and the reliability of nonclinical QT data as a predictor of arrhythmias in humans is still superseded by a robust clinical assessment and has recently been rediscussed at the ICH [10],in Europe, the risk related to the detection of potentially genotoxic impurities triggered several regulatory requests for supplemental information and even delayed the marketing authorization of some drugs: this resulted in the release of new quality and safety guidelines and their adoption in United States, andthe potential risk for phototoxicity was highlighted in some EU regions and is now subject to regulatory adoption in each region and within ICH guidelines. The potential carcinogenic risk of some biopharmaceuticals (e.g., growth factors) in the United States, in particular, has been highlighted and will be addressed in the S6 ICH guideline revision. In these instances, the issue must be discussed and resolved with the region/country involved on a case-by-case basis.

OVERVIEW OF ICH GUIDELINES

ICH guidelines are grouped into four major categories based on ICH Topic codes:

Q: “quality topics,” guidelines relating to chemical and pharmaceutical quality assurance (e.g., stability and impurity testing),S: “safety topics,” relating to in vitro and in vivo nonclinical studies (e.g., carcinogenicity testing, genotoxicity testing),E: “efficacy topics,” relate to the design and endpoint of clinical studies in humans (e.g., dose–response studies, good clinical practices), andM: “multidisciplinary topics,” group together topics that do not fit into one of the above categories and that may have the other topics (e.g., the CTD)

Key nonclinical regulatory guidelines for assessing the safety of new drugs are in the “S” and “M” topics [4] and is highlighted in Table 2.1. We focus on ICH guidelines, as these reflect the consensus view on nonclinical safety requirements for novel medicines of the principal pharmaceutical-producing regions. The current set of guidelines is considered appropriate for preparing development strategies for the majority of new drugs and appropriate to safeguard healthy volunteers or patients enrolled in clinical studies (see Chapters 5–9). Nevertheless, a critical assessment of development issues and needs should be undertaken before deciding on the nonclinical study package to ensure that innovative technologies, scientific advances, and all available data are taken into account. However, the reader is cautioned that there are still instances of country specific guidelines (e.g., see Table 1 in Chapter 7) such that the toxicological scientist should not simply rely on ICH as the sole source of information. In our view, the current guidelines are generally well balanced. Decisions with respect to controversial and/or complex topics are made based on a sound analysis of the most up-to-date scientific data/techniques and the consensus view within the scientific community of the significance of these data/techniques.

TABLE 2.1 Key regulatory guidelines for the assessment of drug safety.

ICH numberGuidelineM3 (R2)Non-Clinical Safety Studies for the Conduct of human Clinical Trials and Marketing Authorization for PharmaceuticalsS4ADuration of Chronic Toxicity Testing in Animals (Rodent and Nonrodent Toxicity TestingS3BPharmacokinetics: Guidance for Repeated Dose Tissue Distribution StudiesS3AToxicokinetics: The Assessment of Systemic Exposure in Toxicity StudiesS1BTesting for Carcinogenicity of PharmaceuticalsSIC(R2)Dose Selection for Carcinogenicity Studies of PharmaceuticalsS5(R2)Detection of Toxicity to Reproduction for Medicinal Products & Toxicity to Male FertilityS6Preclinical Safety Evaluation of Biotechnology-Derived PharmaceuticalsS7ASafety Pharmacology Studies for Human PharmaceuticalsS7BSafety Pharmacology Studies for Human PharmaceuticalsS2(R1)Genotoxicity Testing and Data Interpretation for Pharmaceuticals Intended for Human UseS8Immunotoxicity Studies for Human PharmaceuticalsS9Nonclinical Evaluation for Anticancer Pharmaceuticals

DIFFERENCES BETWEEN GUIDELINES FOR NBEs AND NCEs

For many years, pharmaceuticals were almost exclusively considered small chemical molecules; however, over the years the importance of biological entities (e.g., antibodies, peptides, proteins, polynucleic acids) in medicines has progressed rapidly. Although the general framework and the main objectives of the current nonclinical guidelines was originally developed and implemented to advance new chemical entities (NCEs), they are still relevant to the development of biotechnology-derived drugs (NBEs). In 1997, the ICH S6 guideline, which deals specifically with the nonclinical evaluation of biotechnology-derived pharmaceuticals, was finalized and adopted. In addition to the standard criteria and endpoints described by the existing guidelines for the development of NCEs, issues specific to NBEs were highlighted in this guideline, and specific issues arose that need to be addressed during the development of NBEs:

cross reactivity and selection of the relevant animal species/model,production of antidrug antibodies and their impact on pharmacokinetic behavior,interference with the host immune system (i.e., immunogenicity), andbatch-to-batch consistency of the test compound, the impact of changes in production, and impurities.

ONGOING REVISIONS TO ICH GUIDELINES

Revision of ICH guidelines is a continuous process (see above). Analysis of the proposed changes to current guidelines is of interest because given the relatively long delay between the entry into development of a test compound and delivery of the final commercial drug it can affect current development strategies. Of most interest in current revision processes (as of December 2009) are the proposed changes to the following guidelines:

1. The S6 guideline, for which a final concept paper for revision was accepted in June 2008, and for which Step 4 is expected for June 2010. Principal issues to be addressed in this review are:

criteria for species selection and study design,reproductive/developmental toxicity,carcinogenicity, andimmunogenicity

A detailed description of the work that will be undertaken can be found elsewhere [11].

2. The S9 guideline, currently at Step 4 for which the principal issues under discussion were:

an approach to setting a safe start dose for clinical trials,a study design to support initial clinical development,duration of repeated dose toxicity testing limited to 3 months,reproduction toxicity requirements only to embryo–fetal toxicology assessment,a flexible approach to evaluating the safety of metabolites and impurities, anddefining the scope and patient population/indication

A detailed description of the work that will be undertaken can be found elsewhere [12].

CONCLUSION

Based on current drug development regulatory guidelines and ongoing revision process that involve some of the most critical guidelines, we can conclude that great efforts have been made during the last decades to align and harmonize nonclinical drug requirements worldwide. Common and well-defined regulatory guidance facilitates drug development, avoids a needless repetition of studies, thus shortening the whole research and development process, and making new drugs available to patients in the shortest time possible and at the lowest cost possible. An additional benefit is to reduce the use of animals, consistent with the 3Rs (replace, reduce, and refine) paradigm. Nonetheless, biomedical sciences and knowledge are continuously evolving along with perceived regulatory needs and guidelines. The ICH process is central to this evolution and provides a forum for openly discussing what is ideally needed, what is possible, and what should be done. An ad hoc evolution of regulatory guidance is avoided, and each constituent (national regulatory agencies, industry, and patients) take part in the debate. Given this constant evolution in requirements, the toxicological scientist has to maintain up-to-date knowledge of national and internationally harmonized drug development guidelines.

REFERENCES

1. Doull J and Bruce MC., 1986. Origin and scope of toxicology. In: CD Klaassen, MO Andur, and J Doull, editors. Casarrett and Doull’s Toxicology: The Basic Science of Poisons, 3rd ed. New York: Macmillan. pp 3–10

2. Ballentine C., 1981. Taste of Raspberries, Taste of Death The 1937 Elixir Sulfanilamide Incident. FDA Consumer magazine June 1981 issue at http://magazine-directory.com/FDA-Consumer.htm

3. Lenz W, 1963. Das Thalidomid-syndrom. Fortschr Med81:148–153

4. ICH, 2009 at http://www.ich.org/

5. EMEA, 2009 at http://www.emea.europa.eu/

6. EFPIA, 2009 at http://www.efpia.org/

7. MHLW, 2009 at http://www.mhlw.go.jp/english/

8. FDA, 2009 at http://www.fda.gov/

9. Pharma, 2009 at http://www.phrma.org/ ICH, 2009c. S9: Nonclinical Evaluation for Anticancer Pharmaceuticals

10. ICH, 2008. E14 Implementation Working Group Questions & Answers at http://www.ich.org/LOB/media/MEDIA4719.pdf

11. ICH, 2009b. Final Concept Paper S6(R1): Preclinical Safety Evaluation of Biotechnology-Derived Pharmaceuticals (Revision of the ICH S6 Guideline) at http://www.ich.org/LOB/media/MEDIA4733.pdf

12. ICH, 2009c. S9 Guideline: Anticancer pharmaceuticals at http://www.ich.org/LOB/media/MEDIA5785.pdf

CHAPTER 3

TOXICOLOGICAL DEVELOPMENT: ROLES AND RESPONSIBILITIES

Franck Chuzel and Bernard Ruty

INTRODUCTION

Clinical studies are designed to determine with a high degree of confidence whether a developmental drug is safe for administration to humans. However, clinical trials cannot begin until the nonclinical safety of the drug candidate has been demonstrated. This involves a range of in vivo toxicology studies, usually in a rodent and a nonrodent, and a range of in vitro assays (see Chapters 5– 9). Given their complexity, these studies require the concerted effort of a multidisciplinary “study team” composed of experts from a range of disciplines (Fig. 3.1) and are subject to stringent (global) regulatory requirements (see Chapter 2 for an overview). An additional complexity is that studies can be “single-site studies” (all activities and procedures related to the study are conducted in one facility) or “multiple-site studies” (one or more study related activities are done at a laboratory/facility that is geographically separated from the site at which the in vivo phase is conducted). Given this background, the efficient organization of study teams, and in particular a clear definition of roles and responsibilities for each contributing team member, is critical to the successful conduct of studies. Good organization and management of study teams will go a long way to avoid and, if necessary, address and overcome technical/scientific problems and interpersonal problems. Many of the problems encountered with in-house studies overlap with those occurring with contract research organizations (CRO) that specialize in toxicology studies (see Chapter 4). For some issues, resolution is simpler for in-house studies, where there is control of all aspects of the study, for others it is simpler for CRO-based studies, where team dynamics may be simpler. In this chapter we review the organization needed to support in-house studies and potential issues and how they may be resolved.

Figure 3.1 Experts from a range of disciplines form the multidisciplinary study tea responsible for nonclinical study conduct and report preparation

INSOURCING VERSUS OUTSOURCING

On occasion, the expertise and/or resources necessary to support toxicity studies is not available in an organization. In this instance, this skill gap can be addressed by hiring specialist scientists or, more economically, CROs. In these cases, a well-defined outsourcing strategy allows a clear definition of activities that must be performed internally and activities that can be subcontracted to an external provider. A good starting point to support this decision is to prepare a comprehensive list of the nonclinical activities and skill profiles needed for the project in question. A matrix decision scheme can then be used (see Fig. 3.2) to help decide which activities should be conducted in house and which activities should be outsourced. Using this approach, activities are divided into four domains:

Figure 3.2 A matrix decision scheme to help decide which activities should be conducted in-house and which activities should be outsourced

1. activities to be outsourced,

2. activities to be kept internally if resources are available,

3. activities to be kept internally unless a CRO has specific expertise in this area, and

4. activities that must absolutely be kept in house.

The allocation of individual study activity to one of these four areas is then made according to two decision criteria: one is the importance of performing the said activity internally and the second is based on the quality and expertise of potential outsourcing partners in the target activity. This type of approach ensures that all toxicology skills/activities needed for a project are made available.

THE STUDY TEAM

The conduct of a toxicology study requires a complex series of activities, tasks, and subtasks to be performed. This presents a considerable organizational complexity that can most efficiently be addressed by dedicated nonclinical toxicology study teams. We recommend that a toxicology study team be created for each study; the role of the team is to manage all aspects of the study and to anticipate and to resolve problems during the life of the study. The procedure for establishing a study team will be company specific, however, in general a “core team” should be established, composed of the scientist and technicians who will be charged with the conduct of the study, data capture, data evaluation, and data interpretation. Therefore, in addition to the study director (SD), there should also be technical team leaders (in life, clinical pathology, and postmortem activities), key members of the technical staff (who are key to the day-to-day organization of operational/technical activities). Ideally, the study pathologist should also be a member of this team (see Fig. 3.3). This core team is supported by the broader technical team/s and administrative staff. How the study team functions will vary from company to company; however, at minimum it should start by critically reviewing the study protocol. This review can be conducted by circulating the draft protocol to the study team, who then pass feedback to the SD and/or in one (or more) prestudy meeting. Specific study needs, potential and/or unresolved issues (scientific, resource, good laboratory practice [GLP]), questions about study-specific procedures should be reviewed and resolved. At this stage, problems can arise due to operational and/or resource constraints; for example, toxicokinetic or clinical pathology investigations may require a blood sampling schedule that cannot be supported by the number of technicians available. These exchanges are also key to a reducing/preventing errors during the study and ensuring that appropriate resources are made available to the study. Early identification, and correction, of issues with the study design will help reduce problems once the study has started. In addition to the study team, which is focused on nonclinical development, there may also be a project team, whose role is tage the drug development project as a whole. These two teams must work in close collaboration and make sure that, at minimum, there is a free flow of information between these teams; how this “flow of information” is achieved will differ between organizations. One widely used approach is appointing a team member (a “project team representative”) with specific responsibility for building and maintaining the link between the two teams and ensuring that cross-consultation occurs on key issues.

Figure 3.3 Composition of a typical nonclinical study team

Given that the study team is composed of a number of subject matter experts, working in close collaboration under pressure of time, conditions are ideal for conflicts to arise between team members. These differences of opinion can occur at any time.. In our experience, problems arise most often with respect to interpreting data, deciding on the scientific strategy to be pursued, and resolving study issues. For example, there may be disagreement on setting the No Observed Effect Level (NOAEL), findings that are used to define the NOAEL or the toxicological significance/relevance of findings. To resolve these differences, teamwork and good communication, supported by a comprehensive and meticulous analysis of data and use of the scientific literature, is needed. One of the first steps to take to resolve these conflicts to ask obvious questions:

Is this a well-recognized and understood finding?Is this finding linked to the pharmacological activity of the compound?Is this finding relevant to humans and/or the clinical use of the compound?Did similar findings occur with other compounds of the same structural and/or pharmacological class?Does any other treatment related effect support one or other of the proposed interpretations?

Experienced members of the team may have dealt with these questions previously and know well-rehearsed strategies for dealing with it. Of course, care is needed to ensure that this does not become an excuse for lack of analysis and innovation. However, if team members cannot agree, then, as a final step, it may be necessary for management to step in and make the final decision.

Another source of conflict can be disagreements between study scientists and technicians. For many study tasks, it is the study technicians who are primarily responsible for handling animals, sampling blood, dosing animals, collecting data, and (at least) conducting a preliminary analysis. For example, recording clinical signs, recording ECGs, and analyzing friction can occur between technical staff and more senior team members when highly experienced technicians have greater practical/technical expertise than more senior (scientist) team members. As discussed earlier, prestudy discussions/meetings will help avert some of these problems, which emphasize the importance of including technical staff in these discussions whenever possible. In general, many, study/project decisions can, and should, be taken in the light of individual expertise, not seniority; however, if all else fails, supervisors or management may need to be involved. Once a decision has been made, usually a compromise in accordance with resource availability and the strategic objectives, the study team must support the decision. This may seem to contradict the GLP requirement that the SD is the “central point of accountability” for studies. However, operationally this is simply an acceptance of the fact that expertise in technical, administrative, and wider strategic constraints does not reside uniquely with the SD.

The Study Director

According to GLP guidelines [1], the SD is the pivot around which toxicity studies are organized and has overall responsibility for the conduct of a study, as well as (at least in theory) for interpreting, analyzing, documenting, and reporting the results. The principal functions of a SD fall into four main categories: technical, scientific, administrative, and GLP compliance. Therefore, any scientist with appropriate education, training, and at least a basic understanding of all the disciplines involved in nonclinical studies can be appointed an SD. An SD who has significant study experience is at a premium because formal training, even to PhD level, usually does not equip the SD with knowledge of the operational aspects of a toxicity study. For most SDs, in-house training is needed to bridge knowledge gaps, and in this respect experienced technical staff can play a key role in familiarizing the SD with the practical elements of study design and feasibility. In addition, the American Board of Toxicology has, for many years, offered a certification for toxicologists [2] and EUROTOX accord European Registered Toxicologists status [3]. Although these certifications/registrations schemes do not guarantee “quality,” they are good indicators of experience in toxicology. The SD should have formal training in life sciences, a degree (ideally a PhD) in their chosen discipline. If possible, the SD group should consist of people of different backgrounds, seniority, and scientific expertise. This increases creativity, innovation, cross-fertilization of knowledge, and flexibility to support most, if not all, toxicity studies that need to be performed. If possible, the SD group should be composed of experts in general toxicity (which usually account for about 60% of the global study activity), genetic toxicology, reproductive toxicology, safety pharmacology, and toxicokinetics/metabolism studies; in practice, this range of expertise is usually only found in house in large companies. Some companies also use experienced technical staff in the role of SD. The advantage of this is that such people have a good knowledge of the technical, operational, and organizational aspects of toxicity studies. However, they may not have sufficient scientific expertise to undertake complex studies (e.g., long-term repeat-dose studies, carcinogenesis studies). This can be addressed by individualized training, focused on the theoretical aspects of toxicology. In any event, however, it is advisable that initially these SDs should be assigned to the less complex toxicity studies (e.g., single-dose or range-finding studies). Overall, this approach provides a good opportunity for high potential technical staff to be developed, and, in addition to the motivation this brings, it also increases flexibility and allows better use of specialists and more experienced SDs.

A study is assigned to the SD by management. The skills needed by the SD vary according to the criticality of the study (pivotal versus nonpivotal) and the type of study (e.g., general toxicity study, reproductive toxicity, immunotoxicity, and mechanistic toxicity). An experienced senior SD may have the expertise to undertake all studies for a given project, a less experienced junior SD will not. The advantage of one SD conducting all toxicity studies for a test compound is that he/she will have up-to-date knowledge of the outcome of previous studies for a given test compound and, consequently, a good understanding of the evolving toxicity profile and potential nonclinical issues. However, this approach may not be possible if the number of projects and studies to be managed by the SD results in an excessive workload. In this case, different SDs have to be used, where good communication and information transfer between SDs involved is essential. The SD must be proactive in identifying and resolving problems. If the SD does not have sufficient expertise to evaluate problems and issues affecting all aspects of the study then the integrity of the study may be compromised. Given the breadth of specialist techniques that support a nonclinical study, in general, the SD must rely on subject matter specialists; in some cases, the problem may be so specialized that the nonspecialist may not be able to fully understand the problem. Thus, the experienced SD is able to recognize what can and cannot be delegated effectively and safely. Although the SD remains the central point of accountability for the study, in reality, the SD must delegate responsibility for decision making about specific issues to subject matter experts. The SD must maintain regular contact with other members of the study team to ensure that they are aware of all major events occurring in the study. This is particularly important from a GLP perspective because, all deviations, planned and unplanned, from the study protocol must be recorded [4]. It is essential that everyone involved in the conduct of the study have sufficient trust in the SD (and management) to report errors without fear of reprisals. Any deviation to the study plan must be part of the final study report and include a statement on the impact of the deviation/s on the quality of the data and the outcome of the study. In addition to scientific and technical skills, an SD must also be able to manage the study team: strong interpersonal skills are essential. In many instances, because the SD is also the central point of toxicological expertise for the development project (particularly in a small size company where resources may be limited), the SD who is a skilled communicator (verbal and written) brings a benefit to the role.

The Study Pathologist