ANG4043, a Novel Brain-Penetrant Peptide–mAb Conjugate, Is Efficacious against HER2-Positive Intracranial Tumors in Mice

Abstract

Anti-HER2 monoclonal antibodies (mAb) have been shown to reduce tumor size and increase survival in patients with breast cancer, but they are ineffective against brain metastases due to poor brain penetration. In previous studies, we identified a peptide, known as Angiopep-2 (An2), which crosses the blood-brain barrier (BBB) efficiently via receptor-mediated transcytosis, and, when conjugated, endows small molecules and peptides with this property. Extending this strategy to higher molecular weight biologics, we now demonstrate that a conjugate between An2 and an anti-HER2 mAb results in a new chemical entity, ANG4043, which retains in vitro binding affinity for the HER2 receptor and antiproliferative potency against HER2-positive BT-474 breast ductal carcinoma cells. Unlike the native mAb, ANG4043 binds LRP1 clusters and is taken up by LRP1-expressing cells. Measuring brain exposure after intracarotid delivery, we demonstrate that the new An2-mAb conjugate penetrates the BBB with a rate of brain entry (K in ) of 1.6 Â 10 À3 mL/g/s. Finally, in mice with intracranially implanted BT-474 xenografts, systemically administered ANG4043 increases survival. Overall, this study demonstrates that the incorporation of An2 to the anti-HER2 mAb confers properties of increased uptake in brain endothelial cells as well as BBB permeability. These characteristics of ANG4043 result in higher exposure levels in BT-474 brain tumors and prolonged survival following systemic treatment. Moreover, the data further validate the An2-drug conjugation strategy as a way to create brain-penetrant biologics for neuro-oncology and other CNS indications.

Promising Approaches to Circumvent the Blood–Brain Barrier: Progress, Pitfalls and Clinical Prospects in Brain Cancer

“…Drug conjugates composed of human p97 and adriamycin or paclitaxel enhanced brain accumulation by tenfold over unconjugated counterparts with p97-adriamycin improving survival time over free adriamycin in mice bearing intracranial gliomas or breast-derived metastatic tumors [96]. Recently, angiopep-2 conjugated to an antibody against HER-2-targeted brain ECs, maintained HER-2-dependent antiproliferative activity against breast cancer cells and improved survival over unconjugated anti-HER-2 in breast-derived intracranial tumors [105]. Development of Ang-1005 has reached clinical trials.…”

Emerging formats for next-generation antibody drug conjugates

“…We feel that existing payloads have high enough potencies, so alternative payloads that have a wider spectrum of action may be needed. ADCs that can access the brain using 'angiopep-antibodies' [119] or other indications such as inflammatory disease and infection may also require alternative antibody formats, again suggesting that 'one size does not fit all'. Is there a danger of ADCs becoming too elaborate, over-engineered and overly complicated?…”

Recent Innovations in Peptide Based Targeted Drug Delivery to Cancer Cells

“…ANG4043 is a novel brain-penetrating peptide–mAb conjugate that is efficient against HER2-positive intracranial tumors in mice (Table 5). This peptide Ab conjugate retains in vitro binding affinity for the HER2 receptor and antiproliferative potency against HER2-positive BT-474 breast ductal carcinoma cells [181]. Applications of angiopeptides as targeting moieties for other anticancer applications are still under investigation [181,182,183,184,185].…”