Definition

A fusion protein composed of a recombinant humanized anti-Claudin18.2 (CLDN18.2; A2 isoform of claudin-18) heavy chain antibody (VHH) fused to an engineered immunoglobulin gamma-1 (IgG1) Fc fragment, with potential immunostimulating and antineoplastic activities. Upon administration, anti-CLDN18.2 heavy chain antibody Fc fusion protein DR30303 specifically targets, binds to and inhibits CLDN18.2 expressed on tumor cells. The binding induces antibody-dependent cellular cytotoxicity (ADCC) and may kill CLDN18.2-expressing tumor cells and inhibit tumor cell proliferation. CLDN18.2, a tight junction protein and stomach-specific isoform of claudin-18, is overexpressed on a variety of tumor cells. Its expression in healthy tissues is strictly confined to short-lived differentiated epithelial cells of the gastric mucosa.