The use of toxicogenomic data in risk assessment: a regulatory perspective

Recent advances in genomic research have provided new insights into mechanisms of toxicity evoked by drugs or xenobiotics. Several governmental and commercial organizations are at present actively building up databases containing large amounts of toxicogenomics information. With promises to improve our ability to characterize hazard, scientists are facing the challenge as to how to link patterns of gene expression and gene clustering to specific adverse effects of toxicants or classes of toxicants. The future of toxicogenomics lies in the robustness of the databases generated. Regulators are working together with institutes and industry in exploring the potential use of these databases in regulatory purposes. It is, however, anticipated that regulatory use of the toxicogenomic databases as supportive information in the assessment procedure of new drug applications will be on a case-by-case basis until the predictive value of the databases is firmly established.     

Developing pharmacogenetic evidence throughout clinical development

Genetics as a discipline is fundamental for the pharmaceutical industry; it contributes to all therapeutic areas and has an impact throughout the research and development continuum, right up to and including clinical practice. Pharmacogenetics is seen as a significant contributor to increasing the efficiency and effectiveness of pharmaceutical R&D, and it enhances the growing interest in personalized medicine. This article discusses some contemporary issues that influence drug development and examines the potential of pharmacogenetics to reduce the risk and uncertainty that are inherent in the drug development process.     

Potential therapeutic targets and the role of technology in developing novel cannabinoid drugs from cyanobacteria

Cyanobacteria find several applications in pharmacology as potential candidates for drug design. The need for new compounds that can be used as drugs has always been on the rise in therapeutics. Cyanobacteria have been identified as promising targets of research in the quest for new pharmaceutical compounds as they can produce secondary metabolites with novel chemical structures. Cyanobacteria is now recognized as a vital source of bioactive molecules like Curacin A, Largazole and Apratoxin which have succeeded in reaching Phase II and Phase III into clinical trials. The discovery of several new clinical cannabinoid drugs in the past decade from diverse marine life should translate into a number of new drugs for cannabinoid in the years to come. Conventional cannabinoid drugs have high toxicity and as a result, they affect the efficacy of chemotherapy and patients’ life very much. The present review focuses on how potential, safe and affordable drugs used for cannabinoid treatment could be developed from cyanobacteria.     

The promise of toxicogenomics

As human genetics and genomics have progressed, culminating in the completion of the rough draft of the human genome in February 2001, new tools and technologies have been developed to identify and quantify global gene expression changes occurring in the cell. These new technologies are allowing researchers to gain an increased understanding of the function and regulation of genes at the systems level, and are transforming virtually all areas of biological research. In the field of toxicology, a new subdiscipline termed toxicogenomics has emerged which promises to identify and characterize the molecular mechanisms that lead to toxicity. Gene expression profiling, through the use of microarray technology, is rapidly becoming a standard analysis in toxicology studies, and has the potential to play a pivotal role in all stages of drug safety evaluation. This review focuses on recent studies in toxicogenomics, and discusses the promises and future challenges in this field.     

Drug discovery, drug development and the emerging world of pharmacogenomics: prospecting for information in a data-rich landscape

Drug development is a very expensive and inefficient process. Currently, it takes on average 15 years and costs approximately US $500 million to bring a new drug to market, with the pharmaceutical industry spending more than US $20 billion in identifying and developing drugs in 1998. Twenty-two percent of this total was spent on screening assays and toxicity testing. Yet the rapidly accelerating advances in high-throughput technologies, including screening and robotics, combinatorial chemistry, and genomics makes this an extremely data-rich environment. Add to that the new paradigms of pharmacogenomics and 'customized medicine', and the question is, are we helping or hurting our cause? Clearly, interpreting this flood of data and turning it into useful information is our next great hurdle. By extending the pharmacogenomic paradigm to the drug discovery process, this paper intends to put the scope of the problem into context.     

Rho Chi lecture. Pharmaceutical sciences in the next millennium

Even a cursory survey of this article suggests that the pharmaceutical sciences are being rapidly transformed under the influence of both the new technologies and sciences and the economic imperatives. Of particular importance are scientific and technological advances that may greatly accelerate the critical process of discovery. The possibility of a drug discovery process built around the principles of directed diversity, self-reproduction, evolution, and self-targeting suggests a new paradigm of lead discovery, one based quite directly on the paradigms of molecular biology. Coupled with the principles of nanotechnology, we may contemplate miniature molecular machines containing directed drug factories, circulating the body and capable of self-targeting against defective cells and pathways -- the ultimate "drug delivery machine." However, science and technology are not the only factors that will transform the pharmaceutical sciences in the next century. The necessary reductions in the costs of drug discovery brought about by the rapidly increasing costs of the current drug discovery paradigms means that efforts to decrease the discovery phase and to make drug development part of drug discovery will become increasingly important. This is likely to involve increasing numbers of "alliances," as well as the creation of pharmaceutical research cells -- highly mobile and entrepreneurial groups within or outside of a pharmaceutical company that are formed to carry out specific discovery processes. Some of these will be in the biotechnology industry, but an increasing number will be in universities. The linear process from basic science to applied technology that has been the Western model since Vannevar Bush's Science: The Endless Frontier has probably never been particularly linear and, in any event, is likely to be rapidly supplanted by models where science, scientific development, and technology are more intimately linked. The pharmaceutical sciences have always been an example of use-directed basic research, but the relationships between the pharmaceutical industry, small and large, and the universities seems likely to become increasingly developed in the next century. This may serve as a significant catalyst for the continued transformation of universities into the "knowledge factories" of the 21st century. Regardless, we may expect to see major changes in the research organizational structure in the pharmaceutical sciences even as pharmaceutical companies enjoy record prosperity. And this is in anticipation of tough times to come.     

Structure-Activity Relationship Study of Novel Peptoids That Mimic the Structure of Antimicrobial Peptides

The constant emergence of new bacterial strains that resist the effectiveness of marketed antimicrobials has led to an urgent demand for and intensive research on new classes of compounds to combat bacterial infections. Antimicrobial peptoids comprise one group of potential candidates for antimicrobial drug development. The present study highlights a library of 22 cationic amphipathic peptoids designed to target bacteria. All the peptoids share an overall net charge of +4 and are 8 to 9 residues long; however, the hydrophobicity and charge distribution along the abiotic backbone varied, thus allowing an examination of the structure-activity relationship within the library. In addition, the toxicity profiles of all peptoids were assessed in human red blood cells (hRBCs) and HeLa cells, revealing the low toxicity exerted by the majority of the peptoids. The structural optimization also identified two peptoid candidates, 3 and 4, with high selectivity ratios of 4 to 32 and 8 to 64, respectively, and a concentration-dependent bactericidal mode of action against Gram-negative Escherichia coli.     

Reducing the harm of "harm reduction"

The US Food and Drug Administration (FDA) is committed to working with the oncology community to expedite the drug evaluation process in view of the many promising new oncology drugs under laboratory development and the time and expense required for such new drugs to reach the patient population. One significant advance would be to enable quantitative imaging as a tumor biomarker. The FDA is working with the pharmaceutical industry, academia, and sister stakeholders in the government, primarily through collaborative educational and research efforts, to identify how imaging can serve this function.     

Chemical biology--understanding biology and advancing therapy

Chemical biology is a new academic discipline whose goals are to understand biological systems using chemistry and chemical compounds. In addition to serving as important biological probes, some of these small molecules could be useful therapeutically. This review will discuss how advances in chemical biology by academics can aid in the discovery of new anti-cancer agents. Specifically, novel molecules can be useful tools to validate a potential target in a disease site and help provide the rationale for a clinical trial with a related molecule developed by industry. These novel molecules can also be developed for clinical use, although obstacles to this approach are recognized. Finally, this review discusses the opportunities to identify off-patent drugs with previously unrecognized anti-cancer activity and how the prior data on the drug would permit it to be rapidly repurposed.     

Involving the pharmaceutical and biotech communities in medication development for substance abuse

Pharmacotherapy as adjunctive treatment is an integral part of the strategy for treating substance abuse. Although there are several approved drugs for the treatment of opioid, alcohol, and nicotine dependence, the pharmaceutical industry, for a variety of reasons, has been reluctant to enter this area to develop medications for substance abuse indications. Therefore, in 1990, a Medication Development Program was established by NIDA to carry out and assist in stimulating development of new pharmacotherapies. It is vital for NIDA to provide clear leadership and establish a collaborative working relationship with the pharmaceutical industry, providing scientific, development, and financial assistance, depending on the size, resources, and expertise of the company. An important NIDA role in this effort is setting standards, such as establishing Target Product Profiles (TPPs), predictive decision trees for selection of clinical candidates, and animal models to evaluate safety and potential effectiveness prior to human studies. NIDA can further establish standards for clinical studies, including Proof of Concept (PoC), Phase 2 (or Learning) trials to establish initial proof of safety and effectiveness, and Phase 3 (or Confirming) trials to validate Phase 2 findings. NIDA and other government agencies need to work to improve industry incentives to participate in medication development for substance abuse. Specific incentives, such as market exclusivity and patent extension, as provided in BioShield and pediatric drug legislation, should be strongly considered. NIDA can further assist industry to navigate the regulatory and, if needed, controlled substance scheduling processes, by establishing a true Federal partnership between NIDA, FDA, and DEA.     

Nontraditional approaches to first-in-human studies to increase efficiency of drug development: will microdose studies make a significant impact?

Much has been written recently about low productivity in the pharmaceutical industry and the high cost of drug development. Over a 10-year period ending in 2000, only approximately 11% of compounds tested in humans across 10 large pharmaceutical companies were eventually approved for marketing in the United States and/or Europe. Attrition was highest during phase II (62%) but still significant in phase III (45%) and at the time of registration (23%). Clearly, given the high cost and time required for clinical development, these late-stage failures are unsustainable.     

Pharmacological mechanism-based drug safety assessment and prediction

Advances in cheminformatics, bioinformatics, and pharmacology in the context of biological systems are now at a point that these tools can be applied to mechanism-based drug safety assessment and prediction. The development of such predictive tools at the US Food and Drug Administration (FDA) will complement ongoing efforts in drug safety that are focused on spontaneous adverse event reporting and active surveillance to monitor drug safety. This effort will require the active collaboration of scientists in the pharmaceutical industry, academe, and the National Institutes of Health, as well as those at the FDA, to reach its full potential. Here, we describe the approaches and goals for the mechanism-based drug safety assessment and prediction program.     

A review of high throughput technology for the screening of natural products.

High throughput screening is commonly defined as automatic testing of potential drug candidates at a rate in excess of 10,000 compounds per week. The aim of high throughput drug discovery is to test large compound collections for potentially active compounds ('hits') in order to allow further development of compounds for pre-clinical testing ('leads'). High throughput technology has emerged over the last few years as an important tool for drug discovery and lead optimisation. In this approach, the molecular diversity and range of biological properties displayed by secondary metabolites constitutes a challenge to combinatorial strategies for natural products synthesis and derivatization. This article reviews the approach of High throughput technique for the screening of natural products for drug discovery.     

What's next in translational medicine?

Translational medicine is the integrated application of innovative pharmacology tools, biomarkers, clinical methods, clinical technologies and study designs to improve disease understanding, confidence in human drug targets and increase confidence in drug candidates, understand the therapeutic index in humans, enhance cost-effective decision making in exploratory development and increase phase II success. Translational research is one of the most important activities of translational medicine as it supports predictions about probable drug activities across species and is especially important when compounds with unprecedented drug targets are brought to humans for the first time. Translational research has the potential to deliver many practical benefits for patients and justify the extensive investments placed by the private and public sector in biomedical research. Translational research encompasses a complexity of scientific, financial, ethical, regulatory, legislative and practical hurdles that need to be addressed at several levels to make the process efficient. Several have resisted the idea of supporting translational research because of its high costs and the fear that it may re-direct funds from other biomedical disciplines. Resistance also comes from those more familiar with traditional clinical research methods. In this review, we argue that translational research should be seen as enabled by ongoing efforts in basic and clinical research and not competing with them. Translational research provides the knowledge necessary to draw important conclusions from clinical testing regarding disease and the viability of novel drug mechanisms. Advancing translational research requires education and new sources of funding. This could be achieved through public and congressional education by a joint coalition of patients' advocacy groups, academia, drug regulatory agencies and industry.     

Predicting inhibitory drug-drug interactions and evaluating drug interaction reports using inhibition constants

OBJECTIVE: To review the use of inhibitory constants (Ki) determined from in vitro experiments in the prediction of the significance of inhibitory drug-drug interactions (DDIs). DATA SOURCES: Searches of MEDLINE (1966-August 2004) and manual review of journals, conference proceedings, reference textbooks, and Web sites were performed using the key search terms cytochrome P450, drug-drug interaction, inhibition constant, and Ki. STUDY SELECTION AND DATA EXTRACTION: All articles identified from the data sources were evaluated, and information deemed relevant was included for this review. DATA SYNTHESIS: The cytochrome P450 isoenzymes factor prominently in the explanation of numerous DDIs. Although the regulation of these enzymes by one drug can affect the pharmacokinetics of other drugs, the consequences may not necessarily be significant either in terms of pharmacokinetic or clinical outcomes. Yet, many DDI monographs originate as unconfirmed case reports that implicate the influence of one drug on the CYP-mediated metabolism of another, and these often uncorroborated mechanisms can eventually become regarded as dogma. One consequence of this process is the over-prediction of potentially important DDIs. The pharmaceutical industry, Food and Drug Administration, and pharmaceutical scientists have developed a strategy for predicting the significance of inhibitory DDIs at the earliest possible stages of drug development based on a new chemical entity's Ki value, determined in vitro. CONCLUSIONS: We suggest that the use of Ki values of drugs purported to behave as CYP inhibitors be incorporated in the assessment of case reports that ascribe DDIs to inhibition of metabolism of one drug by another.     

Antibody-drug conjugates - a perfect synergy

Introduction: There is a great unmet need for effective new treatments in cancer, which continues to be a major cause of death. Antibody-drug conjugates (ADCs) are emerging, after a long gestation, as a class of biopharmaceuticals with the potential to address this need by directing highly potent cytotoxic drugs to their point of action. There is increasing interest in ADCs by major pharmaceutical companies and a growing pipeline of candidates for clinical use. This review summarises progress with development of this new class of drugs. Areas covered: The authors describe separately the antibody and drug elements of ADCs and then examine the technology and consequences of linkage. The work is presented in the light of recent developments in the design, using clinical examples where possible. Expert opinion: Since their emergence as independent drugs, antibodies and chemotherapy are being brought together in effective synergy. The conjunction is timely: many of the technical challenges in preparing antibodies have been addressed; potent new drugs are available and linker technology is advancing apace. ADCs however are not just a sum of their individual parts. The current challenge is in understanding the holistic nature of this exciting class of drugs that promise a new avenue for cancer treatment. Target selection, the interaction of ADC with tumour and off-tumour targets and the internalisation of ADCs, are critical to the effective maturation of ADC technology. Ongoing recent developments in attachment sites and linker chemistry can provide fine-tuning of drug loading, elements of ADC PK and off-target ADC toxicity.     

Small molecules for small minds? The case for biologic pharmaceuticals

Biologic pharmaceuticals are gaining in both market share and clinical utility compared with small molecule therapeutics. This market growth is, in part, reflective of a field of science entering its toddlerhood, where with increased maturity, both development timelines and costs of manufacturing for these complex molecules will decrease, further enhancing the profitability side of the equation. Although a firm understanding of the rules governing toxicity (especially antibody responses to therapeutic proteins) remains to be defined, it is clear that proteins are less prone to much of the idiosyncratic toxicity associated with small molecule drug candidates. Proteins are disadvantaged in that they are unlikely to find much use in targeting intercellular processes; however, they have clear strengths over small molecules in targeting protein–protein interactions and the specific targeting of surface features of particular cells (e.g., in oncology). As each aspect of protein pharmaceutical technology advances, it is clear that this will be the major area for growth in the industry over the next decade.     

Small molecules for small minds? The case for biologic pharmaceuticals

Biologic pharmaceuticals are gaining in both market share and clinical utility compared with small molecule therapeutics. This market growth is, in part, reflective of a field of science entering its toddlerhood, where with increased maturity, both development timelines and costs of manufacturing for these complex molecules will decrease, further enhancing the profitability side of the equation. Although a firm understanding of the rules governing toxicity (especially antibody responses to therapeutic proteins) remains to be defined, it is clear that proteins are less prone to much of the idiosyncratic toxicity associated with small molecule drug candidates. Proteins are disadvantaged in that they are unlikely to find much use in targeting intercellular processes; however, they have clear strengths over small molecules in targeting protein-protein interactions and the specific targeting of surface features of particular cells (e.g., in oncology). As each aspect of protein pharmaceutical technology advances, it is clear that this will be the major area for growth in the industry over the next decade.     

Evolutionary and genetic features of drug targets

In the modern drug discovery pipeline, identification of novel drug targets is a critical step. Despite rapid progress in developing biomedical techniques, it is still a great challenge to find promising new targets from the ample space of human genes. This fact is partially responsible for the situation of “more investments, fewer drugs” in the pharmaceutical industry. A series of recent researches revealed that successfully targeted genes share some common evolutionary and genetic features, which means that the knowledge accumulated in modern evolutionary biology and genetics is very helpful to identify potential drug targets and to find new drugs as well. In this article, we comprehensively summarize the links between human drug targets and genetic diseases and their evolutionary origins, with an attempt to introduce these novel concepts and their medical implications to the biomedical community.     

Drug development and the FDA's Critical Path Initiative

Advances in biomedical research over recent decades have substantially raised expectations that the pharmaceutical industry will generate increasing numbers of safe and effective therapies. However, there are warning signs of serious limitations in the industry's ability to effectively translate biomedical research into marketed new therapies. Clinical pharmacologists should be aware of these signals and their potential impact. Here, we discuss a strategy, where clinical pharmacology can play an important role to improve the process of drug development.