AK006

AK006 is a humanized IgG1 monoclonal antibody developed by Allakos that targets Siglec-6, an inhibitory receptor selectively expressed on mature mast cells. By binding to and activating Siglec-6, AK006 inhibits both IgE-dependent and IgE-independent mast cell activation—including pathways mediated by IgE, MRGPRX2, KIT, IL-33, and C5a—resulting in broad suppression of inflammation. In addition to its inhibitory activity on mast cell activation, AK006 can reduce mast cell numbers via antibody-dependent cellular phagocytosis (ADCP) in the presence of activated macrophages. The drug was investigated for allergic and inflammatory diseases such as chronic spontaneous urticaria (CSU), atopic dermatitis, and prurigo nodularis. Despite demonstrating high receptor occupancy on mast cells and a favorable safety profile in early clinical trials (including subcutaneous administration with ~77% bioavailability and a half-life of 12–22 days), development was discontinued after Phase 1 due to lack of therapeutic efficacy in CSU[1][3][4][5][6][8].