Industry experiences with immune-mediated findings in biotherapeutic nonclinical toxicology studies.

With the growth of monoclonal antibodies and other proteins as major modalities in the pharmaceutical industry, there has been an increase in pharmacology and toxicity testing of biotherapeutics in animals. Animals frequently mount an immune response to human therapeutic proteins. This can result in asymptomatic anti-drug antibody formation, immune complexes that affect drug disposition and/or organ function such as kidney, cytokine release responses, fatal hypersensitivity, or a range of reactions in between. In addition, an increasing number of oncology therapeutics are being developed that enhance or directly stimulate immune responses by a variety of mechanisms, which could increase the risk of autoreactivity and an autoimmune-like syndrome in animals and humans. When evaluating the risk of biotherapeutics prior to entering the clinic, the nonclinical safety data may include any of these responses and it is critical to understand whether they represent a safety liability for humans. The DruSafe Leadership group of the IQ Consortium conducted a survey of industry to understand sponsors' experiences with these immune reactions in nonclinical studies related to both immunogenicity and pharmacologically-mediated immune perturbations. The survey covered what pathways were affected, how the immune responses were presented, how the company and health authorities interpreted the data and whether the immune responses were observed in the clinic. Additionally, the survey gathered information on association of these findings with anti-drug antibodies as well as sponsor's use of immunogenicity predictive tools. The data suggests that the ability of a biotherapeutic to activate the immune system, intended or not, plays a significant role on characteristics of the response and whether theys are translatable.

Tissue Distribution and Elimination of Isavuconazole following Single and Repeat Oral-Dose Administration of Isavuconazonium Sulfate to Rats.

Quantitative whole-body autoradiography was used to assess the distribution and tissue penetration of isavuconazole in rats following single and repeated oral-dose administration of radiolabeled isavuconazonium sulfate, the prodrug of isavuconazole. Following a single-dose administration of radiolabeled isavuconazonium sulfate (labeled on the active moiety), radioactivity was detectable within 1 h postdose in 56 of 65 tissue/fluid specimens. The highest maximum concentrations (Cmax) were observed in bile and liver (66.6 and 24.7 µg eq/g, respectively). The lowest Cmax values were in bone and eye lens (0.070 and 0.077 µg eq/g, respectively). By 144 h postdose, radioactivity was undetectable in all tissues/fluids except liver (undetectable at 336 h) and adrenal gland tissues (undetectable at 672 h). Following daily administration for up to 21 days, 1-h-postdose Cmax values were the highest on or before day 14 in all except seven tissues/fluids, of which only rectum mucosa and small intestine mucosa had Cmax values >25% higher than all other 1-h-postdose values. For 24-h-postdose Cmax values, only large intestine, large intestine mucosa, and urine had the highest Cmax values at day 21. The penetration of single oral doses of unlabeled isavuconazole (25 mg/kg of body weight isavuconazonium sulfate) and voriconazole (50 mg/kg) into rat brain (assessed using liquid chromatography-tandem mass spectrometry) was also compared. Brain concentration/plasma concentration ratios reached approximately 1.8:1 and 2:1, respectively. These data suggest that isavuconazole penetrates most tissues rapidly, reaches a steady state in most or all tissues/fluids within 14 days, does not accumulate in tissues/fluids over time, and achieves potentially efficacious concentrations in the brain.

Translational science approach for assessment of cardiovascular effects and proarrhythmogenic potential of the beta-3 adrenergic agonist mirabegron.

INTRODUCTION: Translational assessment of cardiac safety parameters is a challenge in clinical development of beta-3 adrenoceptor agonists. The preclinical tools are presented that were used for assessing human safety for mirabegron. METHODS: Studies were performed on electrical conductance at ion channels responsible for cardiac repolarization (IKr, IKs, Ito, INa, and ICa,L), on QT-interval, subendocardial APD90, Tpeak-end interval, and arrhythmia's in ventricular dog wedge tissue in vitro and on cardiovascular function (BP, HR, and QTc) in conscious dogs. RESULTS: In conscious dogs, mirabegron (0.01-10mg/kg, p.o.) dose-dependently increased HR, reduced SBP but DBP was unchanged. Propranolol blocked the decrease in SBP and attenuated HR increase at 100mg/kg mirabegron. Mirabegron, at 30, 60, or 100mg/kg, p.o., had no significant effect on the QTc interval. In paced dog ventricular wedge, neither mirabegron nor metabolites M5, M11, M12, M14, and M16 prolonged QT, altered transmural dispersion of repolarization, induced premature ventricular contractions, or induced ventricular tachycardia. Mirabegron nor its metabolites inhibited IKr, IKs, Ito INa, or ICa,L at clinically relevant concentrations. DISCUSSION: Up to exposure levels well exceeding human clinical exposure no discernible effects on ion channel conductance or on arrhythmogenic parameters in ventricular wedge resulted for mirabegron, or its main metabolites, confirming human cardiac safety findings. In vivo, dose-related increases in HR with effects markedly higher than seen clinically, was mediated in part by cross-activation of beta-1 adrenoceptors. This non-clinical cardiac safety test program therefore proved predictive for human cardiac safety for mirabegron.

Effect of mirabegron on plasma gonadotropic and steroidal hormone levels in rats after two weeks of oral administration.

The effects of mirabegron on plasma gonadotropic and steroidal hormone levels in rats were investigated, when administered orally once daily for two weeks to male and female rats at doses of 10, 30, and 100 mg/kg/day, in order to elucidate a potential mechanism for findings in the reproductive system observed in toxicity studies in rats. Significantly decreased body weight gain and food consumption were observed in males and females at 100 mg/kg/day on Days 1 to 4 of dosing. A significantly prolonged estrous interval was observed in females at 100 mg/kg/day and increased liver weights were noted in females at 30 mg/kg/day or greater. No histopathological changes were observed in the pituitary gland, adrenal glands, liver, testes, epididymides, prostate, seminal vesicle, ovaries, uterus, or vagina at any dose. In males, no treatment-related changes in levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, or dihydrotestosterone (DHT) were observed at any dose. Corticosterone levels in males increased in a dose-dependent manner at 30 mg/kg/day or greater. In females, no treatment-related changes in levels of LH, FSH, prolactin, estradiol, progesterone, or corticosterone were observed at any dose in any stage of the estrous cycle. Taken together, these results suggest that mirabegron has no effect on gonadotropic or sex steroidal hormone levels in either sex at doses up to 100 mg/kg/day. In contrast, adrenocortical hormone levels were increased in males at mirabegron doses of 30 mg/kg/day or greater.

Vernakalant selectively prolongs atrial refractoriness with no effect on ventricular refractoriness or defibrillation threshold in pigs.

Vernakalant is a novel antiarrhythmic agent that has demonstrated clinical efficacy for the treatment of atrial fibrillation. Vernakalant blocks, to various degrees, cardiac sodium and potassium channels with a pattern that suggests atrial selectivity. We hypothesized, therefore, that vernakalant would affect atrial more than ventricular effective refractory period (ERP) and have little or no effect on ventricular defibrillation threshold (DFT). Atrial and ventricular ERP and ventricular DFT were determined before and after treatment with vernakalant or vehicle in 23 anesthetized male mixed-breed pigs. Vernakalant was infused at a rate designed to achieve stable plasma levels similar to those in human clinical trials. Atrial and ventricular ERP were determined by endocardial extrastimuli delivered to the right atria or right ventricle. Defibrillation was achieved using external biphasic shocks delivered through adhesive defibrillation patches placed on the thorax after 10 seconds of electrically induced ventricular fibrillation. The DFT was estimated using the Dixon "up-and-down" method. Vernakalant significantly increased atrial ERP compared with vehicle controls (34 ± 8 versus 9 ± 7 msec, respectively) without significantly affecting ventricular ERP or DFT. This is consistent with atrial selective actions and supports the conclusion that vernakalant does not alter the efficacy of electrical defibrillation.

Comparative efficacies of telavancin and vancomycin in preventing device-associated colonization and infection by Staphylococcus aureus in rabbits.

Telavancin is an investigational lipoglycopeptide antibiotic that is active against gram-positive pathogens. In an in vivo rabbit model, subtherapeutic (15-mg/kg) and therapeutic (30- or 45-mg/kg) doses of telavancin were demonstrated to be noninferior and superior to vancomycin (20 mg/kg), respectively, for preventing subcutaneous implant colonization and infection by Staphylococcus aureus.