A Framework Proposal to Follow-Up on Preclinical Convulsive Signals of a New Molecular Entity in First-in-Human Studies Using Electroencephalographic Monitoring.

Traditionally, in dose-escalating first-in-human (FiH) studies, a dose cap with a 10-fold safety margin to the no observed effect level in animals is implemented if convulsive events are observed in animals. However, the convulsive risk seen in animals does not generally translate to humans. Several lines of evidence are summarized indicating that in a dose-escalating setting, electroencephalographic epileptiform abnormalities occur at lower doses than clinical convulsive events. Therefore, we propose to consider the occurrence of epileptiform abnormalities in toxicology studies as premonitory signals for convulsions in dose-escalating FiH studies. Compared with the traditional dose-cap approach, this may allow the exploration of higher doses in FiH and, subsequently, phase II studies without compromising human safety. Similarly, the presence or absence of electroencephalographic epileptiform abnormalities may also aid the assessment of proconvulsive risk in situations of increased perpetrator burden as potentially present in pharmacokinetic and/or pharmacodynamic drug-drug interactions.

Clinical trial considerations on male contraception and collection of pregnancy information from female partner: update.

BACKGROUND: This is an update to our 2012 publication on clinical trial considerations on male contraception and collection of pregnancy information from female partner, after critical review of recent (draft) guidances released by the International Council for Harmonisation [ICH] the Clinical Trial Facilitation Group [CTFG] and the US Food & Drug Administration [FDA]. METHODS: Relevant aspects of the new guidance documents are discussed in the context of male contraception and pregnancy reporting from female partner in clinical trials and the approach is updated accordingly. RESULTS: Genotoxicity The concept of a threshold is introduced using acceptable daily intake/permissible daily exposure to define genotoxicity requirements, hence highly effective contraception in order to avoid conception. The duration for highly effective contraception has been extended from 74 to 90 days from the end of relevant systemic exposure. Teratogenicity Pharmacokinetic considerations to estimate safety margins have been contextualized with regard to over- and underestimation of the risk of teratogenicity transmitted by a vaginal dose. The duration of male contraception after the last dose takes into account the end of relevant systemic exposure if measured, or a default period of five half-lives after last dose for small molecules and two half-lives for immunoglobulins (mAbs). Measures to prevent exposure of the conceptus via a vaginal dose apply to reproductively competent or vasectomized men, unless measurements fail to detect the compound in seminal fluid. CONCLUSION: Critical review of new guidance documents provides a comparison across approaches and resulted in an update of our previous publication. Separate algorithms for small molecules and monoclonal antibodies are proposed to guide the recommendations for contraception for male trial participants and pregnancy reporting from female partners. No male contraception is required if the dose is below a defined threshold for genotoxic concern applicable to small molecules. For men treated with teratogenic mAbs, condom use to prevent exposure of a potentially pregnant partner is unlikely to be recommended because of the minimal female exposure anticipated following a vaginal dose. The proposed safety margins for teratogenicity may evolve with further knowledge.

Clinical development methodology for infusion-related reactions with monoclonal antibodies.

Infusion-related reactions (IRRs) are common with monoclonal antibodies (mAbs) and timely related to drug administration and have been reported as anaphylaxis, anaphylactoid reactions and cytokine release syndrome, among other terms used. We address risk management measures for individual patients and for the study and propose a consistent reporting approach in an attempt to allow cross-molecule comparisons. Once the symptoms of IRR have resolved, the mAb may be restarted. Rechallenge should not be done for suspected IgE-mediated anaphylaxis and Grade 4 IRRs. Management of IRRs for subsequent patients includes administration of premedication, which, however, does not prevent IgE-mediated anaphylaxis. Reporting approach: (1) Report as IRRs, reactions occurring during or within 24 h after an infusion. Negative skin Prick test and absent or undetectable allergen-specific IgE levels have high negative predictive value for an IgE-mediated allergic reaction. If IgE-mediated anaphylaxis is suspected based on medical history and/or laboratory test results, the reaction should be reported as suspected (IgE mediated) anaphylaxis. (2) Collect signs and symptoms with grades to allow characterization of IRRs. IRRs pathogenesis is of scientific interest and has impact on drug development. Animal toxicology studies are neither predictive of severe IRRs nor of anaphylaxis in human. Preclinical tests should be further developed to identify patients at risk for severe IRRs, for complement activation-related pseudoallergy and for IgE-mediated anaphylaxis. The proposed approach should help standardizing data collection and analysis of IRRs in an attempt to enable comparisons across molecules.

Translation strategy for the qualification of drug-induced vascular injury biomarkers.

Drug-induced vascular injury (DIVI) is a common preclinical toxicity usually characterized by hemorrhage, vascular endothelial and smooth muscle damage, and inflammation. DIVI findings can cause delays or termination of drug candidates due to low safety margins. The situation is complicated by the absence of sensitive, noninvasive biomarkers for monitoring vascular injury and the uncertain relevance to humans. The Safer And Faster Evidence-based Translation (SAFE-T) consortium is a public-private partnership funded within the European Commission's Innovative Medicines Initiative (IMI) aiming to accelerate drug development by qualifying biomarkers for drug-induced organ injuries, including DIVI. The group is using patients with vascular diseases that have key histomorphologic features (endothelial damage, smooth muscle damage, and inflammation) in common with those observed in DIVI, and has selected candidate biomarkers associated with these features. Studied populations include healthy volunteers, patients with spontaneous vasculitides and other vascular disorders. Initial results from studies with healthy volunteers and patients with vasculitides show that a panel of biomarkers can successfully discriminate the population groups. The SAFE-T group plans to seek endorsement from health authorities (European Medicines Agency and Food and Drug Administration) to qualify the biomarkers for use in regulatory decision-making processes.

Increased levels of urinary phenylacetylglycine associated with mitochondrial toxicity in a model of drug-induced phospholipidosis.

BACKGROUND: Phospholipidosis (PLD) is a lysosomal storage disorder induced by a class of cationic amphiphilic drugs. However, drug-induced PLD is reversible. Evidence of PLD from animal studies with some compounds has led to discontinuation of development. Regulatory authorities are likely to request additional studies when PLD is linked to toxicity. OBJECTIVE: We conducted a trial to investigate urinary phenylacetylglycine (uPAG) as a biomarker for PLD. MATERIALS AND METHODS: Five groups of 12 male Wistar rats were dosed once with vehicle, 300 mg/kg or 1500 mg/kg of compound A (known to induce PLD), or 300 mg/kg or 1000 mg/kg of compound B (similar structure, but does not induce PLD) to achieve similar plasma exposures. Following dosing, urine and blood samples underwent nuclear magnetic resonance (NMR), proteomic, and biochemical analyses. Necropsies were performed at 48 and 168 h, organ histopathology evaluated, and gene expression in liver analyzed by microarray. Electron microscopic examination of peripheral lymphocytes was performed. RESULTS: For compound A, uPAG increased with dose, correlating with lamellar inclusion bodies formation in peripheral lymphocytes. NMR analysis showed decreased tricarboxylic acid cycle intermediates, inferring mitochondrial toxicity. Mitochondrial dysfunction was suggested by uPAG increase, resulting from a switch to anaerobic metabolism or disruption of the urea cycle. DISCUSSION AND CONCLUSION: uPAG shows utility as a noninvasive biomarker for mitochondrial toxicity associated with drug-induced PLD, providing a mechanistic hypothesis for toxicity associated with PLD likely resulting from combined direct and indirect mitochondrial toxicity via impairment of the proton motor force and alteration of fatty acid catabolism.

Clinical trial considerations on male contraception and collection of pregnancy information from female partners.

BACKGROUND: There is little guidance regarding the risk of exposure of pregnant women/ women of childbearing potential to genotoxic or teratogenic compounds via vaginal dose delivered through seminal fluid during sexual intercourse. METHOD: We summarize current thinking and provide clinical trial considerations for a consistent approach to contraception for males exposed to genotoxic and/or teratogenic compounds or to compounds of unknown teratogenicity, and for collection of pregnancy data from their female partners. RESULTS: Where toxicity testing demonstrates genotoxic potential, condom use is required during exposure and for 5 terminal plasma half-lives plus 74 days (one human spermatogenesis cycle) to avoid conception.For non-genotoxic small molecules and immunoglobulins with unknown teratogenic potential or without a no observed adverse effect level (NOAEL) from embryo-fetal development (EFD) studies and no minimal anticipated biological effect level (MABEL), condom use is recommended for males with pregnant partner/female partner of childbearing potential. For teratogenic small molecules with estimated seminal fluid concentration and a margin between projected maternal area under the curve (AUC) and NOAEL AUC from EFD studies of ≥300 (≥100 for immunoglobulins) or in the absence of a NOAEL with a margin between MABEL plasma concentration and maternal Cmax of ≥300 (≥10 for immunoglobulins), condom use is not required. However, condom use is required for margins below the thresholds previously indicated. For small molecules with available seminal fluid concentrations, condom use is required if margins are <100 instead of <300. Condom use should continue for as long as the projected margin is at or above the defined thresholds. Pregnancy data should be proactively collected if pregnancy occurs during the condom use period required for males exposed to first-in-class molecules or to molecules with a target/class shown to be teratogenic, embryotoxic or fetotoxic in human or preclinical experiments. CONCLUSION: These recommendations, based on a precaution principle, provide a consistent approach for minimizing the risk of embryo-fetal exposure to potentially harmful drugs during pregnancy of female partners of males in clinical trials. Proactive targeted collection of pregnancy information from female partners should help determine the teratogenic potential of a drug and minimize background noise and ethical/logistical issues.

The potential clinical relevance of visible particles in parenteral drugs.

Visible particulates (VP) are one subclass of defects seen during the final visual inspection of parenteral products and are currently one of the top ten reasons for recalls 1,2. The risk posed by particles is still unclear with limited experience reported in humans but remains an important consideration during the manufacture and use of parenteral products. From the experimental and clinical knowledge of the distribution of particulate matter in the body, clinical complications would include events occurring around parenteral administration e.g., as a result of mechanical pulmonary artery obstruction and injection site reaction, or sub-acute or chronic events e.g., granuloma. The challenge is to better understand the implication for patients of single vials with VP and align the risk with the probabilistic detection process used by manufacturers for accept/reject decisions of individual units of product.

Myocardial mononuclear cell infiltrates are not associated with increased serum cardiac troponin I in cynomolgus monkeys.

Myocardial mononuclear cell infiltrate is a spontaneous cardiac finding commonly identified in laboratory cynomolgus monkeys. The infiltrates are predominantly composed of macrophages with lesser lymphocytes and are not typically associated with histologically detectable cardiomyocyte degeneration. These infiltrates are of concern because they confound interpretation of test article-related histopathology findings in nonclinical safety toxicology studies. The interpretation of safety studies would be simplified by a biomarker that could identify myocardial infiltrates prior to animal placement on study. We hypothesized that monkeys with myocardial mononuclear cell infiltrates could be identified before necropsy using an ultrasensitive immunoassay for cardiac troponin I (cTnI). Serum cTnI concentrations in monkeys with myocardial infiltrates were not higher than those in monkeys without infiltrates at any of the sampling times before and on the day of necropsy. Increased serum cTnI levels are not suitable for screening monkeys with myocardial mononuclear cell infiltrates before placement in the study.

In silico assay for assessing phospholipidosis potential of small druglike molecules: training, validation, and refinement using several data sets.

Phospholipidosis (PLD) is a lysosomal storage disorder induced by compounds, notably cationic amphiphilic drugs, which although reversible interferes with cellular phospholipids.The in silico method described utilizes the amphiphilic moment ΔΔG(AM) (kJ/mol) together with basic pK(a) values to assign PLD inducing potential to a compound. The new model was accurate and sensitive (85% and 82%, respectively) when compared to other data sets. Therefore, the parallel in vitro assay for PLD was discontinued. The data reinforce our view that the amphiphilic moment is far more informative for determining a compound's potential to induce PLD than the combined use of basic pK(a) and ClogP values.

The complete pharmacokinetic profile of serum cardiac troponin I in the rat and the dog.

Recent improvements in assays have allowed serum cardiac troponin I (cTnI) to be measured at previously undetectable concentrations, which may have implications for cardiotoxicity studies. We characterized the pharmacokinetics of cTnI after a single iv administration of purified cTnI in rats at doses of 0.005, 0.05, and 0.5 µg/kg and in beagle dogs at doses of 0.05, 0.1, and 0.2 µg/kg. Serum cTnI concentration-time profiles were well described by a two-compartment pharmacokinetic model with first-order elimination in both species. The estimated mean (SD) values of total serum clearance, volume of distribution of the central compartment, and terminal half-life were 318 ml/h/kg, 52.9 ml/kg, and 0.8 h in rats and 481 (135) ml/h/kg, 230 (70) ml/kg, and 1.85 (0.5) h in dogs, respectively. In both species, a fast distribution phase was followed by a relatively slow elimination phase. These data indicate that the current practice in cardiotoxicity studies of unguided blood sampling should be revised. A targeted case-by-case approach is required whereby samples are collected not only relative to the kinetics of the test article but also in relation to the kinetics of the biomarker in the test species and the type and severity of anticipated cardiovascular perturbation. This approach is essential for the identification of subtle increases of serum cTnI concentrations in the low dynamic range.

Detecting signals of drug-drug interactions in a spontaneous reports database.

AIMS: The spontaneous reports database is widely used for detecting signals of ADRs. We have extended the methodology to include the detection of signals of ADRs that are associated with drug-drug interactions (DDI). In particular, we have investigated two different statistical assumptions for detecting signals of DDI. METHODS: Using the FDA's spontaneous reports database, we investigated two models, a multiplicative and an additive model, to detect signals of DDI. We applied the models to four known DDIs (methotrexate-diclofenac and bone marrow depression, simvastatin-ciclosporin and myopathy, ketoconazole-terfenadine and torsades de pointes, and cisapride-erythromycin and torsades de pointes) and to four drug-event combinations where there is currently no evidence of a DDI (fexofenadine-ketoconazole and torsades de pointes, methotrexade-rofecoxib and bone marrow depression, fluvastatin-ciclosporin and myopathy, and cisapride-azithromycine and torsade de pointes) and estimated the measure of interaction on the two scales. RESULTS: The additive model correctly identified all four known DDIs by giving a statistically significant (P < 0.05) positive measure of interaction. The multiplicative model identified the first two of the known DDIs as having a statistically significant or borderline significant (P < 0.1) positive measure of interaction term, gave a nonsignificant positive trend for the third interaction (P = 0.27), and a negative trend for the last interaction. Both models correctly identified the four known non interactions by estimating a negative measure of interaction. CONCLUSIONS: The spontaneous reports database is a valuable resource for detecting signals of DDIs. In particular, the additive model is more sensitive in detecting such signals. The multiplicative model may further help qualify the strength of the signal detected by the additive model.

Evaluation of the rabbit Purkinje fibre assay as an in vitro tool for assessing the risk of drug-induced torsades de pointes in humans.

BACKGROUND: The issue of drug-induced QT interval prolongation and torsades de pointes represents a major concern for pharmaceutical development. In this investigation, we examined the value of the isolated rabbit Purkinje fibre as an in vitro action potential (AP) assay to predict the potential of drugs to induce these undesirable adverse effects. METHODS: First, we categorised the proarrhythmic risk of 26 medicinal products based on proportional reporting ratios for these two adverse events recorded in a US FDA database (Spontaneous Reporting System/Adverse Event Reporting System). Second, we measured drug effects on AP in rabbit Purkinje fibres. Finally, the results of the two analyses were compared to evaluate the predictive value of the in vitro assay. RESULTS: Analysis of the clinical data classified the drugs into 14 positive, 7 negative and 5 questionable for proarrhythmic risk. Based on in vitro electrophysiological profiles, the drugs were grouped into four categories: (i) profile 1 drugs prolong repolarisation without slowing depolarisation; (ii) profile 2 drugs prolong repolarisation and also slow depolarisation; (iii) profile 3 drugs shorten repolarisation; and (iv) profile 4 drugs are without effects. All 14 clinical-positive drugs fell into profiles 1 or 2 (prolongers) with low safety margins (except probucol, which showed no effect, probably because of its low solubility). Clinical-negative drugs belonged mostly to profiles 3 or 4 (non-prolongers) [except clemastine and amlodipine, which were prolongers but had large safety margins]. Clinical-questionable drugs either did not prolong or prolonged slightly but produced additional electrophysiological effects opposing prolongation. CONCLUSION: The rabbit Purkinje fibre is a valuable assay for evaluating the proarrhythmic liability of pharmaceuticals as it can reveal complex electrophysiological profiles that modulate repolarisation delay.