Abstract 864: ANG4043: A new brain-penetrant peptide-antibody conjugate that reduces tumor growth in a HER2-positive orthotopic tumor model.

While monoclonal antibodies to receptor tyrosine kinases such as HER2 have been demonstrated to reduce tumor size and increase survival, these agents achieve little to no brain penetration, making them ineffective against metastatic brain tumors. The blood-brain barrier (BBB), which restricts entry of proteins such as mAbs into the brain, is comprised of capillary endothelial cells with tight junctions and efflux pumps. Brain entry of nutrients, hormones, and other required molecules is accomplished by processes such as receptor-mediated transcytosis. As low-density lipoprotein receptor-related protein 1 (LRP1) is known to perform this function in BBB endothelial cells, we have created a family of peptides (Angiopeps) designed for LRP1 recognition. These proprietary Angiopeps can be used to create novel Peptide-Drug Conjugates that successfully cross the BBB by LRP1-mediated transcytosis. Here we describe chemical conjugation of Angiopep-2 (An2) to a mAb against HER2. This Peptide-Antibody Conjugate, ANG 4043, displays HER2 binding affinity and in vitro cytotoxic potency similar to that of native anti-HER2. ANG4043 demonstrates a high rate of entry into the brain, consistent with achieving therapeutic concentrations. The plasma half-life of ANG4043 is similar to that of Anti-HER2 in mouse. Mice with intracranially implanted BT-474 cells showed reduced brain tumor size when dosed with ANG4043 compared to controls. Overall, these data demonstrate that a brain-penetrant Peptide-Antibody Conjugate is efficacious in a mouse HER2-positive tumor model. These results extend the validation of An2 conjugation beyond small molecules and peptides to include larger molecules such as therapeutic mAbs for development of new brain-penetrant antitumor therapeutics. Citation Format: Jean E. Lachowicz, Michel Demeule, Christian Che, Sasmita Tripathy, Jean-Christophe Currie, Anthony Regina, Tran Nguyen, Simon Lord-Dufour, Jean-Paul Castaigne. ANG4043: A new brain-penetrant peptide-antibody conjugate that reduces tumor growth in a HER2-positive orthotopic tumor model. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 864. doi:10.1158/1538-7445.AM2013-864