Signal management in pharmacovigilance and human risk assessment of CpG 7909, integrating embryo-fetal and post-natal developmental toxicity studies in rats and rabbits.

The potential reproductive and developmental toxicity of the synthetic oligodeoxynucleotide (ODN) CpG 7909, a component of GSK's AS15 immunostimulant, was examined in rat and rabbit studies following intermittent intramuscular injections. Previous studies using subcutaneous and intraperitoneal injections in mice, rats and rabbits revealed that CpG ODNs induced developmental effects. To analyze the safety signal, GSK conducted additional animal studies using the intended clinical route of administration.

FcRn Expression on Placenta and Fetal Jejunum during Early, Mid-, and Late Gestation in Minipigs.

Developmental toxicity testing of therapeutic antibodies is most often conducted in nonhuman primates owing to lack of cross-reactivity in other species. Minipigs may show cross-reactivity for some humanized antibodies but have not been used for developmental toxicity testing due to an assumed lack of embryo-fetal exposure. Unlike in humans, maternal IgGs do not cross the porcine placenta to reach the fetus.

Reporting of teratology studies.

The regulatory toxicology report is an unusual document that requires a particular skill to write. The report must be clear, accurate, concise, and focused. A clear and direct writing style is required.

Skeletal examination by alizarin staining.

A skeletal examination of fetuses is required in regulatory embryo-fetal development studies. This chapter describes a method of skeletal examination using alizarin staining. All fetuses are removed from the mother by caesarean section before birth.

Teratology studies in the rabbit.

The rabbit is generally the non-rodent species or second species after the rat recommended by the regulatory authorities and is part of the package of regulatory reproductive studies for the detection of potential embryotoxic and/or teratogenic effects of pharmaceuticals, chemicals, food additives, and other compounds, including vaccines (see Chapters 1-7).Its availability, practicality in housing and in mating as well as its large size makes the rabbit the preferred choice as a non-rodent species. The study protocols are essentially similar to those established for the rat (Chapter 9), with some particularities.

Combined fertility and embryotoxicity study.

Under normal circumstances, fertility and embryotoxicity studies are run separately according to the ICH S5(R2) guideline for the detection of toxicity to reproduction of medicinal products (1). However, the flexible approach of the S5(R2) guideline also allows the reproduction stages covered in the fertility and embryo-fetal development studies (stages A to D) to be combined into a single study design. The administration period covers the pre-mating and gestation phases through to closure of the hard palate.