Characterization of the selective in vitro and in vivo binding properties of crenezumab to oligomeric Aβ

Abstract

Background: Accumulation of amyloid β (Aβ) in the brain is proposed as a cause of Alzheimer's disease (AD), with Aβ oligomers hypothesized to be the primary mediators of neurotoxicity. Crenezumab is a humanized immunoglobulin G4 monoclonal antibody that has been shown to bind to synthetic monomeric and aggregated Aβ in vitro; however, less is known about the binding characteristic in vivo. In this study, we evaluated the binding patterns of crenezumab to synthetic and native forms of Aβ both in vitro and in vivo. Methods: Crenezumab was used to immunoprecipitate Aβ from synthetic Aβ preparations or brain homogenates from a PS2APP mouse model of AD to determine the forms of Aβ that crenezumab interacts with. Following systemic dosing in PS2APP or nontransgenic control mice, immunohistochemistry was used to localize crenezumab and assess its relative distribution in the brain, compared with amyloid plaques and markers of neuritic dystrophies (BACE1; LAMP1). Pharmacodynamic correlations were performed to investigate the relationship between peripheral and central target engagement. Results: In vitro, crenezumab immunoprecipitated Aβ oligomers from both synthetic Aβ preparations and endogenous brain homogenates from PS2APP mice. In vivo studies in the PS2APP mouse showed that crenezumab localizes to regions surrounding the periphery of amyloid plaques in addition to the hippocampal mossy fibers. These regions around the plaques are reported to be enriched in oligomeric Aβ, actively incorporate soluble Aβ, and contribute to Aβ-induced neurotoxicity and axonal dystrophy. In addition, crenezumab did not appear to bind to the dense core region of plaques or vascular amyloid. Conclusions: Crenezumab binds to multiple forms of amyloid β (Aβ), particularly oligomeric forms, and localizes to brain areas rich in Aβ oligomers, including the halo around plaques and hippocampal mossy fibers, but not to vascular Aβ. These insights highlight a unique mechanism of action for crenezumab of engaging Aβ oligomers.

The amyloid hypothesis in Alzheimer disease: new insights from new therapeutics

“…Like solanezumab 49 , however, crenezumab treatment results in a rapid increase in peripheral Aβ, as monomeric Aβ is captured by the antibody 50 . Crenezumab does not bind avidly to amyloid plaques when administered to transgenic PS2APP mice 51 , and therefore we consider that crenezumab's primary target is monomeric Aβ. Crenezumab was tested in two identical phase III trials (CREAD 1 and 2) at 60 mg/kg i.v.…”

Quantitative systems pharmacology model of the amyloid pathway in Alzheimer's disease: Insights into the therapeutic mechanisms of clinical candidates

“…The binding affinity for each form is mAbspecific, with solanezumab binding strongly to monomers only; crenezumab binding strongly to oligomers, moderately to monomers, and weakly to fibrils and plaques; and aducanumab and gantenerumab binding strongly to fibrils, plaque, and oligomers, and weakly to monomers (Table 2). 28,[30][31][32][33] Following subcutaneous or intravenous dosing with an mAb, the model follows mAb transport into the CSF and brain via passive diffusion. The pharmacokinetics (PK) of the mAb is described by a target-mediated drug <1.42 19 (determined as cutoff for Aβ+) Typical range 1.17-1.37 19 Shaw et al 16 Jack et al 19 Mehta et al 17 Maruyama et al 18…”

“…The binding affinity for each form is mAb‐specific, with solanezumab binding strongly to monomers only; crenezumab binding strongly to oligomers, moderately to monomers, and weakly to fibrils and plaques; and aducanumab and gantenerumab binding strongly to fibrils, plaque, and oligomers, and weakly to monomers (Table 2 ). 28 , 30 , 31 , 32 , 33 …”

“… a Assumption used because crenezumab binds plaque poorly relative to oligomers. 33 b Estimated from Crespi et al 32 …”

Safety, Tolerability, and Pharmacokinetics of Crenezumab in Patients with Mild-to-Moderate Alzheimer’s Disease Treated with Escalating Doses for up to 133 Weeks

“…In vitro, crenezumab prevents A␤ aggregation, promotes disaggregation, and provides a neuroprotective effect by blocking the interaction between A␤ oligomers and neurons [13,14]. Following in vivo dosing in AD transgenic mice, crenezumab localized to brain areas with putative high concentrations of A␤ oligomers (i.e., hippocampal mossy fiber tract and the periphery of amyloid plaques) but not to the dense core of plaques or vascular amyloid [16]. Additionally, the low effector function of the IgG4 backbone and lack of crenezumab binding to vascular amyloid are hypothesized to minimize inflammation in brain vasculature and result in a reduced risk of amyloidrelated imaging abnormalities (ARIA) and localized microvascular damage [13]; this may allow for high doses of crenezumab to be administered without compromising safety.…”