Pharmacokinetics and Pharmacodynamic Effect of a Blood-Brain Barrier-Crossing Fusion Protein Therapeutic for Alzheimer's Disease in Rat and Dog.

PURPOSE: We have recently demonstrated the brain-delivery of an Amyloid-ß oligomer (Aßo)-binding peptide-therapeutic fused to the BBB-crossing single domain antibody FC5. The bi-functional fusion protein, FC5-mFc-ABP (KG207-M) lowered both CSF and brain Aß levels after systemic dosing in transgenic mouse and rat models of Alzheimer's disease (AD). For development as a human therapeutic, we have humanized and further engineered the fusion protein named KG207-H. The purpose of the present study was to carry out comparative PK/PD studies of KG207-H in wild type rat and beagle dogs (middle-aged and older) to determine comparability of systemic PK and CSF exposure between rodent species and larger animals with more complex brain structure such as dogs. METHOD: Beagle dogs were used in this study as they accumulate cerebral Aß with age, as seen in human AD patients, and can serve as a model of sporadic AD. KG207-H (5 to 50 mg/kg) was administered intravenously and serum and CSF samples were serially collected for PK studies and to assess target engagement. KG207-H and Aß levels were quantified using multiplexed selected reaction monitoring mass spectrometry. RESULTS: After systemic dosing, KG207-H demonstrated similar serum pharmacokinetics in rats and dogs. KG207-H appeared in the CSF in a time- and dose-dependent manner with similar kinetics, indicating CNS exposure. Further analyses revealed a dose-dependent inverse relationship between CSF KG207-H and Aß levels in both species indicating target engagement. CONCLUSION: This study demonstrates translational attributes of BBB-crossing Aß-targeting biotherapeutic KG207-H in eliciting a pharmacodynamic response, from rodents to larger animal species.

Induction of Type I Diabetes Mellitus in Beagle Dogs Using Alloxan and Streptozotocin.

This article describes a protocol for chemically inducing type I diabetes mellitus in beagle dogs using a mixture of alloxan (ALX) and streptozotocin (STZ). ALX and STZ are both cytotoxic, diabetogenic agents that cause necrosis of pancreatic ß-cells and therefore halt the production of insulin. Although both compounds are widely used in experimental animal models of diabetes, standard protocols employing a single high dose of either agent are also implicated in adjacent organ damage. In contrast, combined administration of ALX and STZ allows for the use of lower doses, a method that effectively destroys ß-cells and circumvents unwanted adverse effects. The procedures described in this protocol produce persistent, insulin-dependent hyperglycemia in beagle dogs using combined doses of ALX and STZ lower than those previously described for a single intravenous administration. This model can be used to test experimental compounds indicated for the treatment of diabetes. © 2022 Wiley Periodicals LLC. Basic Protocol: Induction of type I diabetes mellitus in beagle dogs using alloxan and streptozotocin.

Sphingolipids and DHA Improve Cognitive Deficits in Aged Beagle Dogs.

Canine cognitive dysfunction syndrome (CDS) is a disorder found in senior dogs that is typically defined by the development of specific behavioral signs which are attributed to pathological brain aging and no other medical causes. One way of objectively characterizing CDS is with the use of validated neuropsychological test batteries in aged Beagle dogs, which are a natural model of this condition. This study used a series of neuropsychological tests to evaluate the effectiveness of supplementation with a novel lipid extract containing porcine brain-derived sphingolipids (Biosfeen®) and docosahexaenoic acid (DHA) for attenuating cognitive deficits in aged Beagles. Two groups (n = 12), balanced for baseline cognitive test performance, received a daily oral dose of either test supplement, or placebo over a 6-month treatment phase. Cognitive function was evaluated using the following tasks: delayed non-matching to position (DNMP), selective attention, discrimination learning retention, discrimination reversal learning, and spatial discrimination acquisition and reversal learning. The effect of the supplement on brain metabolism using magnetic resonance spectroscopy (MRS) was also examined. A significant decline (p = 0.02) in DNMP performance was seen in placebo-treated dogs, but not in dogs receiving the supplement, suggesting attenuation of working memory performance decline. Compared to placebo, the supplemented group also demonstrated significantly improved (p = 0.01) performance on the most difficult pattern of the spatial discrimination task and on reversal learning of the same pattern (p = 0.01), potentially reflecting improved spatial recognition and executive function, respectively. MRS revealed a significant increase (p = 0.048) in frontal lobe glutamate and glutamine in the treatment group compared to placebo, indicating a physiological change which may be attributed to the supplement. Decreased levels of glutamate and glutamine have been correlated with cognitive decline, suggesting the observed increase in these metabolites might be linked to the positive cognitive effects found in the present study. Results of this study suggest the novel lipid extract may be beneficial for counteracting age-dependent deficits in Beagle dogs and supports further investigation into its use for treatment of CDS. Additionally, due to parallels between canine and human aging, these results might also have applicability for the use of the supplement in human cognitive health.