Genotoxic and mutagenic potential of 7-methylxanthine: an investigational drug molecule for the treatment of myopia

7-Methylxanthine (7-MX, CAS No. 552-62-5, purity 99.46%) is the first orally administered drug candidate, which showed anti-myopic activity in different pre-clinical studies. In the present study, we investigated the in-vivo genotoxic and mutagenic toxicity of 7-MX in Wistar rats using comet/single-cell gel electrophoresis, chromosomal aberration and micronucleus assays after oral administration. For the single-dose study (72 h), two doses of 7-MX 300 and 2000 mg/kg body weight were selected. For a repeated dose 28 d study, three doses (250, 500, and 1000 mg/kg) of 7-MX were selected. The doses were administered via oral gavage in the suspension form. Blood and major vital organs such as bone marrow, lung and liver were used to perform comet/single cell gel electrophoresis, chromosomal aberration, and micronucleus assays. The in-vitro Ames test was performed on TA98 and TA100 strains. In the chromosomal aberration study, a non-significant increase in deformities such as stickiness, ring chromosome, and endoreduplication was observed in bone marrow cells of 7-MX treated groups. These chromosomal alterations were observed upon treatment with doses of 2000 mg/kg single dose for 72 h and 1000 mg/kg repeated dose for 28 d. At a dose of 500 mg/kg, DNA damage in terms of tail length, tail moment, % tail DNA and the olive tail moment was also found to be non-significant in 7-MX treated groups. The Ames test showed the non-mutagenic nature of 7-MX in both strains of TA98 and TA100 of Salmonella typhimurium with or without metabolic activation. Thus, the present work is interesting in view of the non- genotoxicity and non-mutagenicity of repeated doses of 7-MX.

New phenotypic cytotoxicity assay for ROS-inducing compounds using rat renal epithelial cells

An important mechanism of chemical toxicity is the induction of oxidative stress through the production of excess reactive oxygen species (ROS). In this study, we show that the level of drug-induced ROS production between NRK52E and HepG2 cells is significantly different for several marketed drugs and a number of Takeda's internal proprietary compounds. Nifedipine, a calcium channel blocker and the initial focus of the study, was demonstrated to promote in vitro ROS production and a decrease in cell viability in NRK52E cells but not HepG2 cells. ROS production after nifedipine treatment was inhibited by a NOX inhibitor (GKT136901) but not the mitochondrial NADH dehydrogenase inhibitor, rotenone, suggesting that nifedipine decreases NRK52E cell viability primarily through a NOX-mediated pathway. To understand the breadth of NOX-mediated ROS production, 12 commercially available compounds that are structurally and/or pharmacologically related to nifedipine as well as 172 internal Takeda candidate drugs, were also evaluated against these two cell types. Over 15 % of compounds not cytotoxic to HepG2 cells (below 50 μM) were cytotoxic to NRK52E cells. Our results suggest that a combination of cell viability data from both NRK52E and HepG2 cells was superior for the prediction of in vivo toxicity findings when compared to use of only one cell line. Further, the NRK52E cell viability assay is a good predictor of NOX-mediated ROS production and can be used as a follow up assay following a negative HepG2 response to aid in the selection of suitable compounds for in vivo toxicity studies.

Enabling speed to clinic for monoclonal antibody programs using a pool of clones for IND-enabling toxicity studies

The importance of speed to clinic for medicines that may address unmet medical needs puts pressure on product development timelines. Historically, both toxicology and first-in-human clinical materials are generated using the same clonal-derived cells to ensure safety and minimize any development risks. However, cell line development with single cell cloning is time consuming, and aggravated by the time needed to screen for a lead clone based on cell line stability and manufacturability. In order to achieve faster timelines, we have used pools of up to six clones for earlier production of drug substance for regulatory filing-enabling toxicology studies, and then the final single clone was selected for production of clinical materials. This approach was enabled by using platform processes across all stages of early development, including expression vectors, host cell lines, media, and production processes. Through comprehensive cell culture and product quality analysis, we demonstrated that the toxicology material was representative of the clinical material for all six monoclonal antibody programs evaluated. Our extensive development experience further confirmed that using a pool of clones for toxicology material generation is a reliable approach to shorten the early development timeline.

The Identification of Pivotal Transcriptional Factors Mediating Cell Responses to Drugs With Drug-Induced Liver Injury Liabilities

Drug-induced liver injury (DILI) is a leading cause of drug attrition during drug development and a common reason for drug withdrawal from the market. The poor predictability of conventional animal-based approaches necessitates the development of alternative testing approaches. A body of evidence associates DILI with the induction of stress-response genes in liver cells. Here, we set out to identify signal transduction pathways predominantly involved in the regulation of gene transcription by DILI drugs. To this end, we employed ATTAGENE's cell-based multiplexed reporter assay, the FACTORIAL transcription factor (TF), that enables quantitative assessment of the activity of multiple stress-responsive TFs in a single well of cells. Homogeneous reporter system enables quantitative functional assessment of multiple transcription factors. Nat. Methods 5, 253-260). Using this assay, we assessed TF responses of the human hepatoma cell line HepG2 to a panel of 64 drug candidates, including 23 preclinical DILI and 11 clinical DILI compounds and 30 nonhepatotoxic compounds from a diverse physicochemical property space. We have identified 16 TF families that specifically responded to DILI drugs, including nuclear factor (erythroid-derived 2)-like 2 antioxidant response element, octamer, hypoxia inducible factor 1 alpha, farnesoid-X receptor, TCF/beta-catenin, aryl hydrocarbon receptor, activator protein-1, E2F, early growth response-1, metal-response transcription factor 1, sterol regulatory element-binding protein, paired box protein, peroxisome proliferator-activated receptor, liver X receptor, interferone regulating factor, and P53, and 2 promoters that responded to multiple TFs (cytomegalovirus and direct repeat 3/vitamin D receptor). Some of TFs identified here also have previously defined role in pathogenesis of liver diseases. These data demonstrate the utility of cost-effective, animal-free, TF profiling assay for detecting DILI potential of drug candidates at early stages of drug development.

Imaging mass spectrometry in drug development and toxicology

During the last decades, imaging mass spectrometry has gained significant relevance in biomedical research. Recent advances in imaging mass spectrometry have paved the way for in situ studies on drug development, metabolism and toxicology. In contrast to whole-body autoradiography that images the localization of radiolabeled compounds, imaging mass spectrometry provides the possibility to simultaneously determine the discrete tissue distribution of the parent compound and its metabolites. In addition, imaging mass spectrometry features high molecular specificity and allows comprehensive, multiplexed detection and localization of hundreds of proteins, peptides and lipids directly in tissues. Toxicologists traditionally screen for adverse findings by histopathological examination. However, studies of the molecular and cellular processes underpinning toxicological and pathologic findings induced by candidate drugs or toxins are important to reach a mechanistic understanding and an effective risk assessment strategy. One of IMS strengths is the ability to directly overlay the molecular information from the mass spectrometric analysis with the tissue section and allow correlative comparisons of molecular and histologic information. Imaging mass spectrometry could therefore be a powerful tool for omics profiling of pharmacological/toxicological effects of drug candidates and toxicants in discrete tissue regions. The aim of the present review is to provide an overview of imaging mass spectrometry, with particular focus on MALDI imaging mass spectrometry, and its use in drug development and toxicology in general.

Use of Genotoxicity Data to Support Clinical Trials or Positive Genetox Findings on a Candidate Pharmaceutical or Impurity …. Now What?

Results from carcinogenicity studies are generally not available for drugs until the time of approval. Many people, including healthy volunteers are often exposed to pharmacologically active doses of the drug before carcinogenicity results are available. The Food and Drug Administration (FDA) Center for Drug Evaluation and Research uses results of genetic toxicology studies as a surrogate for carcinogenicity during the drug development phase (clinical trials). A number of issues are considered in deciding whether drugs that give positive results in genetic toxicology studies can be given to subjects in clinical trials. These relate to the drug indication, the target population, duration of treatment, and importance of the drug. In general, single-dose clinical studies are permitted regardless of the genetox results. In situations where a genetic toxicology assay showed a positive result, some review divisions have asked sponsors to perform a Syrian hamster embryo (SHE) cell transformation assay or a p53 carcinogenicity study prior to allowing repeat-dose clinical trials to proceed. This paper discusses alternatives to SHE cell and p53 assays when faced with a positive result in a genetic toxicology assay. In addition, this paper discusses factors to consider when setting limits for genotoxic impurities in drug substances and products.

15th Annual Meeting of the Safety Pharmacology Society: Focus on traditional sensory systems

INTRODUCTION

This report summarizes and comments key talks on the five traditional senses (ear, vestibular system, vision, taste, olfaction, and touch) which were delivered during the 2015 Annual Meeting of the Safety Pharmacology (SP) Society.

AREAS COVERED

The functional observational battery (FOB) can detect major candidate drug liabilities only on ear, touch and vision. Anatomy, physiology, pharmacology, and pathology notions on each sensory system introduce speaker talks. Techniques for evaluating drug effects on hearing functions are reviewed. Nonclinical approaches to assess vestibular toxicity leading to balance deficits are presented. Retinal explants studied with multielectrode arrays allow the identification of drug liability sites on the retina. Routinely performed Safety Pharmacology assays are not powered to address candidate drug-induced disturbances on taste and smell. This weakness needs correction since unintended pharmacological impairment of these sensorial functions may have serious health consequences. Neuropathy produced by chemotherapeutic agents may cause multiple sensorial perception distortions.

CONCLUSIONS

Safety Pharmacology studies should ensure the safety of any candidate drug on the five sensorial systems.

Ion channel profiling to advance drug discovery and development

In vitro pharmacological profiling provides crucial information to eliminate drug candidates with potential toxicity early in drug discovery and reduce failure in later stages. It has become a common practice in industry to test lead compounds against a panel of ion channel targets for selectivity and safety liability at early drug discovery stages. Ion channel profiling technologies include binding assays, flux assays, fluorescent membrane potential assays, automated and conventional electrophysiology. Instead of examining compound effects on individual ion channel targets, automated current clamp, optical electrophysiology, and multi-electrode assays have evolved to investigate the integrated compound effects on cardiac myocytes. This review aims to provide an overview of ion channel profiling for cardiac safety and comparisons of various technologies.

Genomic models of short-term exposure accurately predict long-term chemical carcinogenicity and identify putative mechanisms of action

BACKGROUND

Despite an overall decrease in incidence of and mortality from cancer, about 40% of Americans will be diagnosed with the disease in their lifetime, and around 20% will die of it. Current approaches to test carcinogenic chemicals adopt the 2-year rodent bioassay, which is costly and time-consuming. As a result, fewer than 2% of the chemicals on the market have actually been tested. However, evidence accumulated to date suggests that gene expression profiles from model organisms exposed to chemical compounds reflect underlying mechanisms of action, and that these toxicogenomic models could be used in the prediction of chemical carcinogenicity.

RESULTS

In this study, we used a rat-based microarray dataset from the NTP DrugMatrix Database to test the ability of toxicogenomics to model carcinogenicity. We analyzed 1,221 gene-expression profiles obtained from rats treated with 127 well-characterized compounds, including genotoxic and non-genotoxic carcinogens. We built a classifier that predicts a chemical's carcinogenic potential with an AUC of 0.78, and validated it on an independent dataset from the Japanese Toxicogenomics Project consisting of 2,065 profiles from 72 compounds. Finally, we identified differentially expressed genes associated with chemical carcinogenesis, and developed novel data-driven approaches for the molecular characterization of the response to chemical stressors.

CONCLUSION

Here, we validate a toxicogenomic approach to predict carcinogenicity and provide strong evidence that, with a larger set of compounds, we should be able to improve the sensitivity and specificity of the predictions. We found that the prediction of carcinogenicity is tissue-dependent and that the results also confirm and expand upon previous studies implicating DNA damage, the peroxisome proliferator-activated receptor, the aryl hydrocarbon receptor, and regenerative pathology in the response to carcinogen exposure.

Target organ profiles in toxicity studies supporting human dosing: an assessment of recovery and chronic dosing

We have previously reported the profile of toxic effects with respect to target organs (defined as organs showing histopathological changes) observed in rodent and non-rodent toxicity studies conducted prior to first time in man (FTIM) for 77 AstraZeneca candidate drugs (CDs) across a range of therapy areas. The main objectives of the current study were twofold; to determine which target organs observed in the FTIM studies recovered after a dose free recovery period and to determine which additional target organs were observed in subsequent chronic (⩾3month) studies required to support longer term clinical dosing. The analysis showed that ⩾86% of findings in studies supporting FTIM either fully or partially resolved at the end of the recovery period, with profiles of recovery that were similar whether the CD progressed into man or not and across different therapy areas. Compared to observations in FTIM studies, chronic studies identified toxicities in an additional 39% of target organs. Overall these data demonstrate that chronic studies in both rodents and non-rodents provide valuable information for the risk assessment for longer term dosing in humans. In addition, the high levels of recovery demonstrated in this analysis suggest that inclusion of recovery assessments on FTIM studies should be on a case-by-case basis driven by a positive indication of need. This is in line with ICH non-clinical guidance that states that reversibility of severe nonclinical toxicities of potential clinic relevance should be assessed 'when appropriate', but that the evaluation can be based on a study of reversibility or on a scientific assessment.

A systems-level approach to resolve tension between research misconduct and confidentiality

The author examines methods of resolving tensions between confidentiality and research conduct and methods of avoiding these tensions. He mentions universities are obligated to address misconduct allegations and considers how to do this while respecting confidentiality between patient and therapist. He comments an underlying aspect of research ethics is a core commitment to honesty and states students are obligated to self-report even when patient-therapist confidentiality restricts reporting.

Utility of positive controls in assessing assay sensitivity in ICH S7B and ICH E14 guidance for evaluation of QT/QTc interval prolongation

Positive controls have often been used in nonclinical and clinical cardiovascular safety studies to evaluate the study's assay sensitivity with respect to drug-induced prolongation of the QT interval of the electrocardiogram (ECG). If the study is able to detect such QT prolongation by the control, then a finding of negative QT effect of comparable size for the test drug will constitute evidence that the test drug does not in fact prolong the QT interval by the amount of regulatory concern. Current regulatory guidance regarding QT interval prolongation includes ICH S7B (nonclinical) and ICH E14 (clinical). However, the underlying null hypothesis settings of the two documents are quite different. This paper quantitatively evaluates the utility of positive controls in nonclinical and clinical studies in which a test drug and a positive control are simultaneously assessed in a study. The results show that positive controls, when powered at 80%, can be beneficial in 58% of nonclinical QT studies with Prob(S)=0.8; when powered at 90%, positive controls can be beneficial 73% of clinical QT studies with Prob(S)=0.9, where Prob(S) represents the probability of success with no QT risk at the stage of development.

Aclidinium bromide, a novel long-acting muscarinic M3 antagonist for the treatment of COPD

Aclidinium bromide is a novel, inhaled, long-acting antimuscarinic agent being developed by Almirall Prodesfarma SA and Forest Laboratories Inc as a once-daily treatment for COPD. In preclinical studies, aclidinium bromide demonstrated a comparable profile to tiotropium bromide, with a slightly quicker onset of action but shorter duration of action. Clinical trials have demonstrated an unquestionably interesting pharmacological profile characterized by a faster rate of onset of the smooth muscle relaxing activity than tiotropium bromide and a rapid plasma hydrolysis in human plasma to inactive metabolites that may account for its favorable cardiovascular safety profile. However, the disappointing efficacy results of the recent phase III trials have cast doubt on the real advantage of introducing this drug on the market. Discussions with the FDA concluded that more trials are needed to assess selected dosing regimens, including higher and/or more frequent doses. At the time of publication, further phase III trials with aclidinium bromide were ongoing, and the developing companies were also extending development to combinations of aclidinium bromide with formoterol or an undisclosed inhaled corticosteroid.

[Stem cell-based in vitro models as alternative methods for toxicity and efficacy tests in animals]

Regarding toxicity and efficacy tests of pharmacological and chemical substances (REACH legislation in Europe), there is a strong need to develop alternative methods for animal in vivo studies, in particular for human in vitro models. Here we present results from early phases of projects exploring the potential of embryonic stem cell models, with a special emphasis on embryo toxicity and neuronal stress.We have been able to demonstrate key functional read-outs of neural hESC models, in addition to representing mechanistic aspects which are characteristic for ischemia or excitotoxicity. There is agreement that these mechanisms underlie a variety of human neurodegenerative diseases. We discuss the possibilities to develop more precise endpoints on the molecular level and present an example of a protein biomarker signature emerging from a European FP6 project about embryo toxicity (www.reprotect.eu), employing murine and human embryonic stem cell models.

Alternative designs of phase II trials considering response and toxicity

Phase II clinical trials in oncology are used to initially evaluate the therapeutic efficacy of a new treatment regimen. Simon's two-stage design is commonly used for such trials. However, he only focused on the "response rate", the proportion of patients experiencing tumor regression. In clinical practice, it is preferred of a sequential design to monitor antitumor activity as well as toxicity. Conaway and Petroni proposed a method for designing phase II trials on the basis of both treatment efficacy and safety, which imply an equal weighing of response and toxicity. In this paper, we developed an alternative test to cope with the trade-off between safety and efficacy. The main idea is to control for the marginal type I errors of response rate and toxicity rate separately. We provide guides on searching the stopping and rejecting regions and determination of sample size. The proposed method has advantage over other designs, including those of Conaway and Petroni's and Bryant and Day's, that it can definitely control one type I error of the interests such as treatment antitumor activity or safety and is robust against the real association parameter. Furthermore, it is conceptive intuitive, very simple to implement, and also feasible for the requirement of small sample size in a phase II trial.

Regulatory perspectives of Type II prodrug development and time-dependent toxicity management: Nonclinical Pharm/Tox analysis and the role of comparative toxicology

Many therapeutic agents are prepared in prodrug forms, which are classified into Type I, II and subtypes A, B based on their sites of conversion. Recently, an increasing number of INDs have appeared as Type II prodrugs that often contain dual tracks of toxicity profile exploration, one on the prodrug and another on the active drug. A comparative toxicology analysis is introduced here to assist reviewers to evaluate the dual toxicity profiles effectively. The analysis helps determine which toxicity is contributed by the prodrug itself, its intermediates, or the active drug itself. As prodrug INDs, or any other new molecular entity (NME) INDs progress into advanced phases of toxicology development, analysis of time-dependent component of toxicity expression, regarding the emergence of new target organs over time, becomes more significant. A strategy is developed to address Pharm/Tox issues such as what duration is required for a toxicity to emerge at the exposure level achieved or dose studied, how many animals in the group are affected, whether the toxicity is a cross-species phenomenon, and whether it is reversible, etc. In conclusion, dual-track comparative toxicology can be useful in the understanding of Type II prodrug's mechanism of toxicity, and that time-dependent toxicology analysis offers means to detecting new toxicity emergence over time. Both approaches could significantly facilitate secondary and tertiary review processes during IND development of a prodrug or NME.

A canine model used to simultaneously assess potential neurobehavioural and cardiovascular effects of candidate drugs

INTRODUCTION

Unwanted effects of drugs on neurobehavioural and cardiovascular functions are normally assessed in separate studies and using different animals. A new model using dogs which allows for the integration of these assessments into a single study was established and validated, adopting the most sophisticated technologies for both monitoring behaviour by video recordings and cardiovascular parameters by telemetry.

METHODS

Conscious male beagle dogs (n=4) were given single oral doses of vehicle, and D-amphetamine (0.25, 0.75, 1.5 mg/kg) or acepromazine (0.05, 0.3, 2 mg/kg) within two different studies. Blood pressure, heart rate, electrocardiogram (EKG), body temperature, motor activity and behaviour (by video) were monitored continuously for 24 h post-dose. Animals underwent a full neurobehavioural examination the day before dosing, at the time to the maximal plasma concentration (Tmax) and 24 h post-dose.

RESULTS

D-Amphetamine: a dose-dependent increase in arterial blood pressure was noted at all doses and was generally associated with an increase in the QA interval, an index of cardiac contractility. Heart rate also increased but only at the 1.5 mg/kg dose. A dose-dependent general excitatory state of the nervous system was observed, characterised mainly by hyper-reactivity, and stereotyped activities. Acepromazine: a decrease in systolic blood pressure was detected at 0.3 and 2 mg/kg generally associated with a decrease in pulse pressure reflecting a negative inotropic effect. A dose-related increase in heart rate accompanied this effect. Dose-dependent general depression of the nervous system was noted; mainly characterised by half-closed eyes, subdued behaviour and impaired posture. In both studies, all dogs completely recovered at approximately 16 h after treatment.

DISCUSSION

Cardiovascular and neurobehavioural changes expected from the pharmacology of test substances were accurately detected. No significant fluctuations of the telemetric parameters recorded were noted as a consequence of the handling associated with the direct neurobehavioural examination. These results confirm the validity of this combined model capable of providing a reliable neurobehavioural and cardiovascular assessment of drugs.

Methods of joint evaluation of efficacy and toxicity in phase II clinical trials

Phase II clinical trials in oncology are usually conducted to evaluate the anti-tumor effect. Because phase I trials are small studies, the maximum tolerated dose of a new drug may not be precisely established and the recommended dose used may lead to excessive toxicity. We investigate the methods proposed by Conaway-Petroni and Bryant-Day allowing early termination of phase II clinical trials and based on joint evaluation of treatment efficacy and safety. Both study designs are computed to minimize the expected accrual under the null hypothesis. As two criteria are considered, the null hypothesis is an area. Each method defines two specific type I error risks. Bryant-Day demonstrate that response and toxicity may be considered as independent (Phi=1). We compare the properties of these two methods with exact calculation according to objective criteria and present one example from a study conducted in France. The two methods differ with regard to the definition of the risks and the assumption of independence. They are similar in terms of expected accruals when Phi=1. Deviations from the assumption of independence induce minor consequences on the type I error risks when the constraint on the type II error risk is less than 15%. Choosing Phi has a minimal impact on expected accrual. Finally, one type I error risk (alpha00) defined by Conaway-Petroni dramatically increases in the case of deviation from the assumption made on Phi. Due to its robustness in relation to a deviation from the independence assumption, we recommend the use of the Bryant-Day method in clinical practice.

Neuronal cell culture from human embryonic stem cells as in vitro model for neuroprotection

In the context of efficacy testing of pharmacological compounds in animal models, replacement of some of these models with a relevant human in vitro system appears attractive, in particular with regard to large scale screening. Here, we show results from initial phases of a project, which attempts to explore the outstanding potential of human embryonic stem cell (hESC)-based in vitro models with special regard to neuronal stress as a potential replacement of animal models for human neurodegenerative diseases. We show the functionality of neurons derived from hESC precursors by calcium imaging, mitochondrial potential measurements and Western blots and moreover demonstrate that this model reproduces crucial mechanistic aspects observed during ischemia and excitotoxicity that are thought to be at the core of some neurodegenerative diseases. Also, the broader possibilities for refining surrogate molecular information emerging from the detailed analysis of this model are discussed.

The embryonic stem cell test for the early selection of pharmaceutical compounds

Potential teratogenicity is a major consideration in the development of pharmaceutical substances. Currently its assessment involves large numbers of animal tests at high cost. This study assessed the feasibility of using the embryonic stem cell test (EST), validated by ECVAM in 1999, as a tool for the prediction of embryonic toxicity of pharmaceutical substances early in their development programmes. ESTs were carried out on 6 chemicals with well established toxicity characteristics established from literature and from the ECVAM study, and then on 10 Roche internal pharmaceutical substances already tested in vivo. The model correctly classified 81% of the substances. Further experiments are necessary to increase the database of the assay.

Genetic toxicity assessment: employing the best science for human safety evaluation. Part II: Performances of the in vitro micronucleus test compared to the mouse lymphoma assay and the in vitro chromosome aberration assay

The in vitro micronucleus test is commonly used in the early stages of pharmaceutical development as a predictive tool for the regulatory mouse lymphoma assay or in vitro chromosome aberration test. The accumulated data from this assay leads to the suggestion that it could be used as an alternative to the chromosome aberration test or the mouse lymphoma assay in the regulatory genotoxicity battery. In this paper, we present the results of the in vitro micronucleus test on L5178Y mouse lymphoma cells with 25 compounds from Servier research and have compared these results to those obtained in the genotoxicity regulatory battery. All the negative compounds were also negative in the in vitro micronucleus assay. Among the 14 positive compounds, two of them, positive in the mouse lymphoma assay, were found negative in the in vitro micronucleus test. However, this apparent discordance was likely to be due to cytotoxicity- or high concentration-related false positive responses in the mouse lymphoma assay. In addition, we confirmed that the in vitro micronucleus assay is useful for detecting aneugens, especially, when cells in metaphasis and multinucleated cells are also scored and when cells are allowed to recover after the long treatment. On this series of compounds, the in vitro micronucleus assay showed high sensitivity and possibly a better specificity than the mouse lymphoma assay. Thus, the in vitro micronucleus assay was shown to be at least as adequate as the mouse lymphoma assay or the in vitro chromosome aberration test to be used in the standard genotoxicity battery.

Investigational PPAR-gamma agonists for the treatment of Type 2 diabetes

The tremendous increase in the global prevalence of Type 2 diabetes (T2D) and its conglomeration of metabolic disorders has dramatically intensified the search for innovative therapies to fight this emerging epidemic. Over the last decade, the family of nuclear receptors, especially the peroxisome proliferator-activated receptors (PPARs), has emerged as one of the most important drug targets aimed at combating the metabolic syndrome. Consequently, compounds that activate the PPARs have served as potential therapeutics for the treatment of T2D and the metabolic anomalies associated with this disorder. This review focuses on the currently marketed compounds and also describes the discovery and development of the next generation of PPAR ligands that are under investigation for the potential treatment of T2D and the metabolic syndrome.

The presence of drug in control samples during toxicokinetic investigations--a Novartis perspective

During a submission procedure, the validity of a few dietary toxicity studies was questioned because low levels of the drug were detected among control toxicokinetic samples. Although several lines of reasoning suggested that these findings arose from ex vivo contamination, the Regulatory Authority stated that it was not possible to establish a no-effect-level in any of the studies and so the submission was withdrawn. In response, Novartis conducted a thorough review and modification of the procedures involved in the collection and analysis of toxicokinetic samples to minimize such contamination in future studies. Ongoing monitoring of contamination in toxicology studies has subsequently revealed that although it was not possible to completely eliminate the problem, the new procedures together with an increasing awareness of the issue have considerably reduced the incidence of contamination. The process of contamination and its control was also modeled in a feeding study in mice. This provided good evidence that the detection of drug in control samples in the previous studies originated from external sources and not from in vivo exposure.

Immune assessments in developmental and juvenile toxicology: Practical considerations for the regulatory safety testing of pharmaceuticals

The developing organism is considered to be more sensitive than the adult to immunotoxic agents. There is every reason, therefore, to include immune assessments in the regulatory testing for developmental toxicity of drugs that are intended to be used in young patients or pregnant woman. An effective strategy would be to incorporate immune assessments in the existing recommendations on pre- and post-natal toxicity study in the rat from the International Conference on Harmonisation. Immune assessments could also be included in juvenile toxicity studies to screen for effects resulting from post-natal exposure to the drug. Adequate testing methods are available to screen for developmental effects that result in immune depression. Routine immune assessments may comprise histopathological examination of the lymphoid organs/tissues and immunophenotyping of lymphocyte subsets in the blood, spleen, or thymus. These tests should be performed in rodents at various ages and at various stages of pre- and post-weaning development. Immunoglobulin and cytokine measurements, assessment of the T-cell dependent antigen response to sheep red blood cells or keyhole limpet haemocyanin antigens, and host resistance studies may be performed as apical tests at maturity. More research is required to develop methods for the detection of drugs that may render the developing organism more susceptible to hypersensitivity or autoimmunity.

[Off-label use in dermatological practice. The conflict between professional duty and legal requirements]

When making therapeutic decisions, doctors often find themselves faced with a dilemma regarding ethical, professional, legal liability, social and service aspects of their duties. These conflicts may be enhanced when medications have to be prescribed for non-approved usages, known as off-label prescribing, because existing therapy options have been exhausted. This option become considerably more difficult since the German Federal Social Court decision of March 2002 which limited off-label use to a number of very strictly defined circumstances. In order to clarify the basis for taking decisions in a given situation, an oncology expert commission has been formed under the coordination of the Department of Health and Social Security. However, this is no solution for the great variety of uncommon dermatological diseases which often require off-label medication usage.

Phenotypic screening for pharmaceuticals using tissue constructs

Compounds can be screened for pharmaceutical activity either by detecting interactions with specified target molecules such as receptors or enzymes (molecular screening) or observing effects on the structure or physiological activities of cells or tissues (phenotypic screening). Screening at the molecular level has been greatly enhanced by fluorescence methods. Especially the combination of confocal detection with measurements of the amplitudes and time courses of fluorescence fluctuations have reduced sample volumes to < microliters and have increased throughputs to >100000 compounds per day. Screening at the molecular level, however, does not provide information about the effects of test compounds on cellular functions. Phenotypic screening, although much slower than molecular screening, does provide information about effects on cell or tissue structure or function and therefore can be used to eliminate at an early stage compounds that are toxic or do not produce the desired cellular response. Tissue constructs reconstituted using cells of specified types and defined extracellular matrix components provide test systems for detecting the effects of test compounds on cellular mechanical functions such as the development of contractile force and on cell and matrix structure and stiffness. For example, constructs based on vascular smooth muscle cells provide information about effects on cellular contractile force that can be used to identify agents that control blood pressure. Tissue constructs that mimic skeletal, smooth and heart muscles and connective tissues have been produced and can be used to study mechanical and structural responses to active compounds.

Neurotoxicity of active compounds--establishment of hESC-lines and proteomics technologies for human embryo- and neurotoxicity screening and biomarker identification

Pharmaceutical and chemical industries are facing new challenges for hazard and risk assessment from regulatory agencies. Especially for potential embryotoxicity of active compounds, conclusions from animal testing remain problematic due to numerous species-specific effects. Developmental toxicity screening preferentially should be performed with human material. Appropriate models are scarce or missing, and the development of a human in vitro model for the molecular characterisation of embryotoxic effects appears to be highly desirable. The outstanding advantages of a human embryonic stem cell (hESC) based in vitro screening model for embryonic neurotoxicity become clear from corresponding results from a murine ESC-screening system. This in vitro test system is based on neuronal differentiated murine embryonic stem cells and quantitative differential proteomic display techniques to identify biomarkers for neurotoxicity. Results are superior to those of conventional array technologies (nucleic acids), because the proteomic analysis covers posttranslational modifications. Under the new strict guidelines for stem cell importation of the German Ministry of Health and a Central Ethics Commission for Stem Cell Research, it is now possible for the first time to exploit the outstanding features of human embryonic stem cells to establish an innovative screening method for embryo- and neurotoxicity and to identify toxicity biomarkers without using animal-based in vitro or in vivo systems.

Early microdose drug studies in human volunteers can minimise animal testing: Proceedings of a workshop organised by Volunteers in Research and Testing

Testing the safety and efficacy of a successful human medicine involves many laboratory animals, which can sometimes be subjected to considerable suffering and distress. Also, it is necessary to extrapolate from the test species to humans. UK and European legislation requires that Replacement, Reduction and Refinement of animal procedures (the Three Rs) are implemented wherever possible. Over the last decade, there has been substantial progress with applying in vitro and in silico methods to both drug efficacy and safety testing. This paper is a report of the discussions and recommendations arising from a workshop on the role that might be played by human volunteer studies in the very early stages of drug development. The workshop was organised in November, 2001 by Volunteers in Research and Testing, a group of individuals in the UK which launched an initiative in 1994 to identify where and how human volunteers can participate safely in biomedical studies to replace laboratory animals. It was considered that conducting pre-Phase I very low dose human studies (sub-toxic and below the dose threshold for measurable pharmacological or clinical activity) could enable drug candidates to be assessed earlier for in vivo human pharmacokinetics and metabolism. Moreover, accelerator mass spectrometry (AMS), nuclear magnetic resonance (NMR) spectroscopy and positron emission tomography (PET) are potentially useful spectrometric and imaging methods that can be used in conjunction with such human studies. Some, limited animal tests would still be required before pre-Phase I microdose studies, to take account of the potential risk posed by completely novel chemicals. The workshop recommended that very early volunteer studies using microdoses should be introduced into the drug development process in a way that does not compromise volunteer safety or the scientific quality of the resulting safety data. This should improve the selection of drug candidates and also reduce the likelihood of later candidate failure, by providing in vivo human ADME data, especially for pharmacokinetics and metabolism, at an earlier stage in drug development than is currently the case.

The role of investigative molecular toxicology in early stage drug development

Molecular toxicology, the application of molecular biology principles and technologies to preclinical safety assessment, represents a key tool for understanding mechanisms of toxicity and assessing the risks associated with specific toxicities. The application of gene expression markers to early stage preclinical safety assessment has the potential to impact pipelines in two main areas: lead optimisation and issue management. Lead optimisation focuses on deprioritising leads with significant, development-limiting toxicological liabilities while advancing those compounds with the greatest chance of successfully navigating the gauntlet of preclinical and clinical safety studies. Issue management utilises mechanistic toxicology studies to position non-development-limiting findings prior to the onset of Good Laboratory Practice studies in full development, and can help to identify and validate gene expression markers predictive of adverse events to avoid issues in second-generation projects. In this review, the authors describe the application of molecular toxicology to a standard pharmaceutical testing funnel, provide examples of the successful application of gene expression markers, and discuss the potential for future impact in several broad categories of clinically relevant toxicity.

Utility of physiologically based pharmacokinetic models to drug development and rational drug discovery candidate selection

The present paper proposes a modeling and simulation strategy for the prediction of pharmacokinetics (PK) of drug candidates by using currently available in silico and in vitro based prediction tools for absorption, distribution, metabolism and excretion (ADME). These methods can be used to estimate specific ADME parameters (such as rate and extent of absorption into portal vein, volume of distribution, metabolic clearance in the liver). They can also be part of a physiologically based pharmacokinetic (PBPK) model to simulate concentration-time profiles in tissues and plasma resulting from the overall PK after intravenous or oral administration. Since the ADME prediction tools are built only on commonly generated in silico and in vitro data, they can be applied already in early drug discovery, prior to any in vivo study. With the suggested methodology, the following advantages of the mechanistic PBPK modeling framework can now be utilized to explore potential clinical candidates already in drug discovery: (i) prediction of plasma (blood) and tissue PK of drug candidates prior to in vivo experiments, (ii) supporting a better mechanistic understanding of PK properties, as well as helping the development of more rationale PK-PD relationships from tissue kinetic data predicted, and hence facilitating a more rational decision during clinical candidate selection, and (iii) the extrapolation across species, routes of administration and dose levels.

Selecting participants when testing new drugs: the implications of age and gender discrimination

Pharmaceutical products are rigorously tested for safety and efficacy prior to being licensed for use. During this testing process the archetypal research subject is a young male; women and older people are less frequently invited to participate. This is especially true at the early stages, but can also occur in the later phases of drug testing. This paper considers the reasons for the relative under-representation of these groups, and the legal implications of failing to include as research subjects the very types of people who will ultimately consume these drugs.

ECVAM and pharmaceuticals

In the pharmaceutical industry, toxicology testing is normally done by preclinical scientists during the Development phase. In the last decade, the implementation of high-throughput screens during the Discovery phase has resulted in an ever-increasing number of lead candidates to be selected for drug development. The low throughput of the conventional safety tests is a bottleneck in the drug-development process. The pharmaceutical industry needs new techniques, down-scaled tests and in vitro alternative test models to determine the absorption, distribution, metabolism, and excretion (ADME) and toxicology profiles of compounds in the late-Discovery phase and/or early in the Development phase. Medium-throughput ADME and toxicity tests will enhance the selection of safer new chemical entities for animals and/or humans. Consequently, this testing strategy will not only reduce the use of resources and the overall development time, but will also result in a substantial decrease in animal use.

In vitro preclinical lead optimisation technologies (PLOTs) in pharmaceutical development

The explosion of genuine high throughput technologies has allowed large compound libraries to be screened with ever increasing biological specificity, exacerbating the problem of lead candidate selection for subsequent drug development. To avoid creating a bottleneck, compounds identified from the high throughput screens undergo lead optimisation, a medium-throughput screen which allows ranking in terms of their basic absorption, distribution, metabolism, excretion (ADME) and toxicological properties. The historical role of the preclinical scientist in the drug discovery/development continuum has been to perform ADME and toxicology studies, simply to support the regulatory submission of lead candidates. This situation is, however, changing with the development of preclinical lead optimisation technologies (Approaches to High Throughput Toxicity Screening, London, Atterwill et al., 1999) facilitating the selection of leading candidates, thereby bridging the gap between high throughput efficacy screens and traditional safety assessment programmes.

Deramciclane (Egis)

Egis, in collaboration with Orion Pharma and Pharmacia, is developing deramciclane, a 5-HT(2A) antagonist and a 5-HT(2C) inverse agonist, as a potential treatment for anxiety disorders [300642]. The compound was also in development for epilepsy but no recent development has been reported for this indication. As of May 2001, comprehensive phase III studies with deramciclane in ten European countries were progressing according to plan [399853], [408534]. By August 2001, phase III studies were also underway in South Africa [420313]. In November 2001, Pharmacia indicated that NDA filing is expected to take place in 2004 [431903]. In February 2001, Orion announced its intention to commercialize deramciclane globally [399853]. In August 2001, Orion and Pharmacia signed an agreement under which the two companies were to collaborate in the development and commercialization of deramciclane in the US [420313]. Analysts at Morgan Stanley predicted in November 2001, that deramciclane would make sales of $25 million in 2004, rising to $150 million in 2005 [435320]. Analysts at Lehman Brothers predicted in December 2001, that deramciclane had a 75% chance of being marketed by 2004, with peak sales potential of $450 million [434768].

CEE-03-310 CeNeS pharmaceuticals

CEE-03-310 is a selective dopamine D1-like receptor antagonist with no appreciable binding affinity for other receptors. Although originally developed by Novo Nordisk A/S as NNC-687 for the treatment of schizophrenia, the company changed its therapeutic focus in the mid-1990s and the full rights to CEE-03-310 and several related compounds were subsequently granted to CeNeS Pharmaceuticals in 1999. CeNeS is currently investigating the drug's potential in the treatment of insomnia and alcohol dependency [340965], [382293], [401496],[416026]. A phase II, double-blind, placebo-controlled trial of CEE-03-310 demonstrated a dose-dependent enhancement of NREM sleep at the beginning of the night without any effects on the quantity of REM sleep [410739].

Embryonic stem cells as an in vitro model for mutagenicity, cytotoxicity and embryotoxicity studies: present state and future prospects

Primary cultures or established cell lines of vertebrates are commonly used to analyse the mutagenic, embryotoxic or teratogenic potential of environmental factors, drugs and xenobiotics in vitro. However, these cellular systems do not include developmental processes from early embryonic stages up to terminally differentiated cell types. An alternative approach has been offered by permanent lines of pluripotent stem cells of embryonic origin, such as embryonic carcinoma (EC), embryonic stem (ES) and embryonic germ (EG) cells. The undifferentiated stem cell lines are characterized by nearly unlimited self-renewal capacity and have been shown to differentiate in vitro into cells of all three primary germ layers. Pluripotent embryonic stem cell lines recapitulate cellular developmental processes and gene expression patterns of early embryogenesis during in vitro differentiation, data which are summarized in this review. In addition, recent studies are presented which investigated mutagenic, cytotoxic and embryotoxic effects of chemical substances using in vitro systems of pluripotent embryonic stem cells. Furthermore, an outlook is given on future molecular technologies using embryonic stem cells in developmental toxicology and embryotoxicology.

Development of a high throughput in vitro toxicity screen predictive of high acute in vivo toxic potential

At an early stage of drug discovery high throughput screens are an invaluable tool to de-select compounds with undesirable properties. A high throughout in vitro toxicity screen has been developed and validated to identify compounds that have a high potential to be acutely toxic in vivo. This screen is based on treating Chinese hamster ovary (CHO) cells with test compounds for 24 h and then determining the degree of cytotoxicity by the reduction of Resazurin. Twenty-six structurally unrelated compounds were chosen that spanned a range of acute LD(50) values and mechanisms of toxicity. The acute LD(50) values (intraperitoneal and intravenous routes) from rat and mouse were taken from the RTECS database. Experimentally derived in vitro IC(35) results were compared to the 'most toxic' (lowest) LD(50) values for each compound. The resulting correlation was statistically significant (r=0.8475). However, due to the scatter of the data points, it was considered not appropriate to rank compounds according to their degree of in vivo toxicity on the basis of the in vitro result. However, by defining cut-off concentrations for both the in vivo (LD(50)) and the in vitro (IC(35)) values it was possible, using the in vitro result (IC(35) <10 microM), to identify compounds that had a high potential to be acutely toxic in vivo ('most toxic' LD(50) <25 micromol/kg). Further development led to a high throughput screen capable of giving a 'Yes', 'No' or 'Borderline' classification as to whether a compound has a high acute in vivo toxic potential. This screen is highly specific (no false positive classifications) and has a sensitivity of approximately 80%. This is deemed acceptable for a first tier toxicity screen at an early stage in the drug discovery process. Transfer of this screen from GlaxoSmithKline UK to sites in Italy, Spain and the USA resulted in very similar findings indicating the inter-laboratory robustness of this screen and therefore the ability to compare results across the GlaxoSmithKline sites.

Pre-clinical methods for detecting the hypersensitivity potential of pharmaceuticals: regulatory considerations

Immune-based systemic hypersensitivities account for a significant number of adverse drug reactions. There appear to be no adequate nonclinical models to predict systemic hypersensitivity to small molecular weight drugs. Although there are very good methods for detecting drugs that can induce contact sensitization, these have not been successfully adapted for prediction of systemic hypersensitivity. Several factors have made the development of adequate models difficult. The term systemic hypersensitivity encompases many discrete immunopathologies. Each type of immunopathology presumably is the result of a specific cluster of immunologic and biochemical phenomena. Certainly other factors, such as genetic predisposition, metabolic idiosyncrasies, and concomitant diseases, further complicate the problem. Therefore, it may be difficult to find common mechanisms upon which to construct adequate models to predict specific types of systemic hypersensitivity reactions. There is some reason to hope, however, that adequate methods could be developed for at least identifying drugs that have the potential to produce signs indicative of a general hazard for immune-based reactions.

Gd-Tex Pharmacyclics Inc

Pharmacyclics is developing Gd-Tex (gadolinium texaphyrin) as a radiosensitizer for the potential treatment of various cancers including brain metastases and primary brain tumors, pancreatic tumors, lung tumors and pediatric cancers [196711], [348919]. The compound entered phase III pivotal trials for brain metastases in September 1998 [323929]. Phase I clinical trials for the treatment of primary brain tumors and pancreatic cancer have been initiated while several trials in other cancer types are in the planning stages [367716]. In September 1998, Pharmacyclics announced the initiation of a pivotal phase III trial for the treatment of patients with brain metastases. This multicenter trial originally included 30 sites in the US, Canada and Europe, and was expected to enroll 425 patients. The FDA agreed that this trial qualified for Fast Track review if efficacy end-points are met [301265]. By October 2000, nearly all 450 patients in 50 sites had been completed [375959], [387023]. In September 2000, Pharmacyclics and the National Cancer Institute (NCI) initiated two phase I trials of Gd-Tex. The first was to determine the safety of two different dosing regimens of the drug during preoperative radiotherapy after induction chemotherapy in patients with stage IIA non-small cell lung cancer (NSCLC). The second would examine the use of Gd-Tex in combination with stereotactic Gamma Knife radiosurgery in patients with primary brain tumors known as glioblastoma multiforme [381561]. A phase Ib/II trial, for brain metastases, was conducted in America and France, and involved over 100 patients. At the ASCO 1998 meeting, interim tumor response data were presented for 37 patients. The overall tumor response rate (complete plus partial response rate) was 73%. Furthermore, MRI scanning confirmed that Gd-Tex accumulated selectively in tumors [287459]. Full results were announced in October 1998 at the American Society of Therapeutic Radiology and Oncology. Following ten daily injections followed by whole brain radiation, 77.7% of patients demonstrated a tumor response defined as greater than 50% reduction in tumor volume. Gd-Tex was well tolerated, and liver enzyme elevation was the dose-limiting effect, which was reversible. Death due to tumor progression was seen in 15% of the Gd-Tex group as opposed to 35% in the control group [302872]. In November 1999, Pharmacyclics commenced a phase I trial of Gd-Tex injection, sponsored by the NCI, for treating children with intrinsic pontine glioma. The goals of the phase I dose-ranging study were to determine the Gd-Tex dose and administration schedule that can be safely administered with radiation and to evaluate the localization of Gd-Tex in affected tumors using MRI [348035]. In March 1997 the Decision Network of the NCI voted to sponsor additional clinical indications including adult and pediatric brain tumors, as well as cancers involving the lung, head & neck, pancreas and prostrate. Two phase I trials of Gd-Tex for the treatment of primary brain tumors commenced in August 1998 under a CRADA with the NCI [237538], [295592], [348919]. Pharmacyclics is collaborating with the NCI under a CRADA in phase I trials in primary brain tumors and pancreatic tumors [323929], [323952], [346596]. Analysts expected a filing to occur by the end of 1999 or early 2000, with sales in 2001 [303186].

Bexarotene ligand pharmaceuticals

Bexarotene (LGD-1069), from Ligand, was the first retinoid X receptor (RXR)-selective, antitumor retinoid to enter clinical trials. The company launched the drug for the treatment of cutaneous T-cell lymphoma (CTCL), as Targretin capsules, in the US in January 2000 [359023]. The company filed an NDA for Targretin capsules in June 1999, and for topical gel in December 1999 [329011], [349982] specifically for once-daily oral administration for the treatment of patients with early-stage CTCL who have not tolerated other therapies, patients with refractory or persistent early stage CTCL and patients with refractory advanced stage CTCL. The FDA approved Targretin capsules at the end of December 1999 for once-daily oral treatment of all stages of CTCL in patients refractory to at least one prior systemic therapy, at an initial dose of 300 mg/m2/day. After an NDA was submitted in December 1999 for Targretin gel, the drug received Priority Review status for use as a treatment of cutaneous lesions in patients with stage IA, IB or IIA CTCL [354836]. The FDA issued an approvable letter in June 2000, and granted marketing clearance for CTCL in the same month [370687], [372768], [372769], [373279]. Ligand had received Orphan Drug designation for this indication [329011]. At the request of the FDA, Ligand agreed to carry out certain post-approval phase IV and pharmacokinetic studies [351604]. The company filed an MAA with the EMEA for Targretin Capsules to treat lymphoma in November 1999 [348944]. The NDA for Targretin gel is based on a multicenter phase III trial that was conducted in the US, Canada, Europe and Australia involving 50 patients and a multicenter phase I/II clinical program involving 67 patients. Targretin gel was evaluated for the treatment of patients with early stage CTCL (IA-IIA) who were refractory to, intolerant to, or reached a response plateau for at least 6 months on at least two prior therapies. Efficacy results exceeded the protocol-defined response target rates; side effects were primarily limited to local skin reactions [349982]. Ligand has worldwide rights to market bexarotene capsules, and will market the drug in the US, Canada and selected European markets. In Spain, Portugal, Greece and Central and South America, Ferrer Internacional will market and distribute the drug. As of December 1999, Ligand was seeking additional distribution partners for select European and Asian markets [351604]. In January 2000, Alfa Wassermann signed an agreement with Ligand to exclusively market and distribute Targretin gel and capsules in Italy. Alfa paid US $0.75 million on signing with additional amounts up to an aggregate total of US $1.0 million on achievement of certain registration milestones, which are expected to be met in 2000 [351882].

Brasofensine NeuroSearch

Brasofensine (NS-2214) is a dopamine reuptake inhibitor under development by NeuroSearch for the potential treatment of Parkinson's disease (PD) [178224]. The compound entered phase II trials in Denmark in November 1996, and phase I trials in the US in January 1996 [195505], [206604]. Bristol-Myers Squibb (BMS) had been codeveloping the compound until June 1999, when it decided to withdraw from the collaboration due to financial restraints of further regulatory requirements (such as additional toxicology documentation) [318365], [329665]. NeuroSearch was seeking licensing agreements with one or more international pharmaceutical companies to accelerate the development and marketing of brasofensine [187758] and had plans to meet with new potential partners for discussions concerning brasofensine licensing in late 1999 [337221]. A more complete evaluation of the effects of brasofensine was anticipated to be obtained through controlled trials, of at least 3 months duration, comparing it with a placebo and the marketed anti-Parkinson's drug, L-DOPA [317406]. In addition, further animal (monkey) tests were planned in order to document the safety of the drug in long-term treatment. These studies were expected to be discussed with the US FDA in October 1999 and, if satisfactory, the 3-month clinical trials were planned to commence in mid-2000 [337221]. At a meeting with the FDA during 1999, NeuroSearch presented plans for developing brasofensine alone. These were found to be satisfactory on condition that further preclinical studies were performed prior to any more clinical development [371542]. In August 2000, Lehman Brothers predicted worldwide sales of US $45 million in 2002 and US $175 million in 2003 [389229]. In February 1999, Lehman Brothers predicted the drug had a 35% probability of reaching market, with an estimated first launch date in 2002. The analysts predicted peak sales would occur in 2009, with sales of $250 million at that time [319225].

RWJ-270201 BioCryst Pharmaceuticals/Johnson & Johnson

RWJ-270201, the lead compound in a series of influenza neuraminidase inhibitors, is under development by BioCryst for the potential treatment of influenza [214908], [337716]. Phase III trials commenced in North America and Europe in February 2000 [355053]. Phase II studies were performed to test the effectiveness of RWJ-270201 at reducing viral titers in infected patients. Data showed that the compound was well tolerated and produced statistically significant reductions in viral titers [337716]. Under a worldwide influenza collaboration formed in September 1998, two subsidiaries of Johnson & Johnson, the RW Johnson Pharmaceutical Research Institute and Ortho McNeil, have received exclusive worldwide rights to RWJ-270201 [298487].

MS-325 EPIX

EPIX is developing MS-325 (AngioMARK), an intravascular magnetic resonance contrast agent for use in the imaging of blood vessels and blood flow in patients with cardiovascular disease, including peripheral vascular disease (PVD). In June 1999, EPIX and Mallinckrodt began phase III trials of MS-325 for the detection of aortoiliac occlusive disease in patients with PVD or abdominal aortic aneurysm [328640]. NDAs for the peripheral and cardiac applications were expected in 1999 and 2000, respectively [275240], [325717]. MS-325 has also shown promise in demonstrating the presence of microscopic muscular dystrophy, as well as monitoring the effects of gene therapy in a mouse model of the disease [360974]. MS-325 is a stable complex of gadolinium and an organic chelating agent. It resembles approved agents in terms of stability, safety and elimination profile, but possesses novel chemical groups which allow it to bind reversibly to albumin. This retains the agent in the blood and, via a patented biophysical phenomenon, enhances the magnetic properties of the gadolinium ion approximately ten-fold.

PNU-142731A Pharmacia

Pharmacia is developing PNU-142731A, a potential lead compound as a treatment for asthma [294718]. It is in phase I clinical trials. PNU-142731A is a potent inhibitor of eosinophilic lung inflammation in rodents, and shows a good bioavailability profile in animals; the mechanism of action is being investigated. Unlike the original compound PNU-104067F, PNU-142731A does not give rise to gall bladder toxicity [295987], [298023].