Pharmacologic characterization of ALD403, a potent neutralizing humanized monoclonal antibody against the calcitonin gene-related peptide

Abstract

ALD403 is a genetically engineered, humanized immunoglobulin G1 monoclonal antibody that inhibits the action of human calcitonin gene-related peptide (CGRP). Clinical trial data indicate that ALD403 is effective as a preventive therapy for migraine and has an acceptable safety profile. For preclinical characterization of ALD403, rabbit antibodies targeting a-CGRP were humanized and modified to eliminate fragment crystallizable (Fc) γ receptor (FcgR) and complement interactions. The ability of ALD403 to inhibit CGRP-induced cAMP production was assessed using a cAMP bioassay (Meso Scale Discovery). The IC50 for inhibition of cAMP release was 434 and 288 pM with the rabbit-human chimera antibody and the humanized ALD403, respectively. ALD403 inhibited α-CGRP binding with an IC50 of 4.7×10-11 and 1.2×10-10 M for the α-CGRP and AMY1 receptors, respectively. ALD403 did not induce antibody-dependent cellular cytotoxicity or complementdependent cytotoxicity and did not stably interact with any of the FcγR mediating these functions, exhibiting only weak binding to FcγRI. ALD403 significantly lowered capsaicininduced blood flow responses in rodents at all time points starting at 5 minutes postapplication in a dose-dependent manner. In conclusion, ALD403 is a potent functional ligand inhibitor of α-CGRP-driven pharmacology. SIGNIFICANCE STATEMENT α-Calcitonin gene-related peptide blockade by ALD403 was assessed via radiolabeled ligand displacement, in vitro inhibition of cell signaling, and in vivo inhibition of capsaicin-induced vasodilation. Lack of engagement of fragment crystallizable- mediated immune-effector functions by ALD403 was shown.