Definition

An antibody-drug conjugate (ADC) composed of OBI-888 (OBI 888), a humanized monoclonal antibody directed against the tumor-associated antigen (TAA) globohexaosylceramide (globo H), covalently linked to monomethyl auristatin E (MMAE), an auristatin derivative and a potent microtubule disrupting agent, with potential antineoplastic activity. Upon administration of anti-globo H/MMAE ADC OBI 999, the antibody moiety of OBI 999, OBI 888, targets and binds to globo H on tumor cells and is rapidly internalized, thereby delivering MMAE intracellularly. Upon proteolytic cleavage, MMAE targets and binds to tubulin and inhibits its polymerization, resulting in G2/M checkpoint arrest and apoptosis in globo H-expressing tumor cells. Globo H, a hexasaccharide glycosphingolipid, is (over)expressed on the surface of many types of tumor cells. Globo H is minimally or not expressed on healthy, normal cells; its expression on cancer cells is associated with increased proliferation and poor prognosis.