Evaluation of gadolinium-based contrast agents in juvenile CD-1 mice including behavioral evaluations.

INTRODUCTION: Seven gadolinium-based contrast agents (GBCAs), four linear and three macrocyclic, were evaluated for potential effects on development, including behavior of juvenile CD-1 mice. METHODS: The GBCAs were administered via intravenous injection once daily on postnatal day (PND) 9, 12, 15, 18, and 21 (PND 1 was the day of delivery) at doses up to twice the human equivalent clinical dose (i.e., 0.63 mmol Gd/kg for gadoxetate disodium and 2.5 mmol Gd/kg for the other GBCAs). Mice were bled for evaluation of exposure (plasma) to gadolinium (Gd) on PND 9, 12, and 70. At scheduled euthanasia, the liver, spleen, brain, skin (dorsal surface), bone (left femur), and kidneys were excised from up to six mice/sex/group on PND 10, 22, or 70 for the determination of Gd levels and histopathological analysis. All mice were monitored for toxicity, growth and survival, sexual maturation, and behavior. CONCLUSION: Gd was quantifiable in the brain tissues with levels declining over time. There was no long-term effect on the growth and development for mice exposed to any of the GBCAs. There was no impact on neurodevelopment as assessed by brain histology and validated neurobehavioral tests, including a functional observational battery, motor activity, and learning and memory as evaluated in the Morris water maze. For all GBCAs, the highest dose tested represented the no-observable-adverse-effect level in juvenile mice.

Evaluation of gadolinium-based contrast agents in pregnant CD-1 mice and subsequent in utero exposure of the developing offspring, including behavioral evaluations.

INTRODUCTION: The offspring of CD-1 mice exposed during pregnancy to one of seven gadolinium-based contrast agents (GBCAs) were evaluated for potential effects on postnatal development and behavior. The GBCAs, comprising four linear (gadopentetate dimeglumine, gadodiamide, gadobenate dimeglumine, and gadoxetate disodium) and three macrocyclic (gadoterate meglumine, gadoteridol, and gadobutrol), were administered via intravenous injection once daily from Gestation Day 6 through 17 following confirmed mating (Day 0) at doses of at least twice the human equivalent recommended clinical dose (i.e., 0.63 mmol Gd/kg for gadoxetate disodium and 2.5 mmol Gd/kg for the other GBCAs). All dams were allowed to deliver naturally. F0 generation females were monitored for maternal toxicity and gadolinium (Gd) levels in blood and brain. Offspring were evaluated for Gd levels in blood and brain at birth and on Day 70 postpartum. F1 generation mice were evaluated for survival and growth preweaning. Selected pups/litter were evaluated postweaning for sexual maturation, growth, and behavior. Gd was quantifiable in the brain of the F1 offspring on PND 1, with levels declining over time. There was no long-term effect of any GBCA on the growth and development of any offspring. There was no impact on neurodevelopment, as assessed by brain histology and validated neurobehavioral tests, including a battery of functional observational tests, motor activity, and learning and memory as evaluated in the Morris water maze. CONCLUSION: At the end of the postweaning period, the highest dose tested was considered the no-observable-adverse-effect level (NOAEL) in the F0 and F1 offspring for all tested GBCAs.

Bypassing nonparallelism of a monoclonal antibody ligand-binding assay by employment of alternative assay formats.

Determination of concentration-time profiles in cynomolgus monkeys of a therapeutic monoclonal antibody against a soluble target revealed a substantial discrepancy between a generic anti-human IgG capture/detection and target bridging assay with the target bridging assay leading to dose- and time-dependent underquantification of drug concentrations, lack of parallelism and subsequently different pharmacokinetic parameters. In contrast, plasma levels derived from a target capture and an anti-idiotypic antibody bridging assay were in close concordance with the generic assay and demonstrated parallelism with high precision across several dilutions. The results provide a practical attempt to overcome nonparallelism by employing alternative assay formats utilizing tailored assay reagent combinations in order to obtain unbiased pharmacokinetic data.

Recommendations from a global cross-company data sharing initiative on the incorporation of recovery phase animals in safety assessment studies to support first-in-human clinical trials.

An international expert group which includes 30 organisations (pharmaceutical companies, contract research organisations, academic institutions and regulatory bodies) has shared data on the use of recovery animals in the assessment of pharmaceutical safety for early development. These data have been used as an evidence-base to make recommendations on the inclusion of recovery animals in toxicology studies to achieve scientific objectives, while reducing animal use. Recovery animals are used in pharmaceutical development to provide information on the potential for a toxic effect to translate into long-term human risk. They are included on toxicology studies to assess whether effects observed during dosing persist or reverse once treatment ends. The group devised a questionnaire to collect information on the use of recovery animals in general regulatory toxicology studies to support first-in-human studies. Questions focused on study design, the rationale behind inclusion or exclusion and the impact this had on internal and regulatory decisions. Data on 137 compounds (including 53 biologicals and 78 small molecules) from 259 studies showed wide variation in where, when and why recovery animals were included. An analysis of individual study and programme design shows that there are opportunities to reduce the use of recovery animals without impacting drug development.