An antibody drug conjugate (ADC) containing the fully human IgG2k monoclonal antibody targeting an epitope of SLC44A4 (AGS-5) linked, via a valine-citrulline (vc) maleimidocaproyl (mc) linker, to the antimicrotubulin drug monomethyl auristatin E (MMAE), with potential antineoplastic activity. The monoclonal antibody moiety of ASG-5ME selectively binds to AGS-5. After internalization and proteolytic cleavage, MMAE binds to tubulin and inhibits its polymerization, which results in G2/M phase arrest and tumor cell apoptosis. SLC44A4, potentially a sodium-dependent transmembrane transport protein, is overexpressed on more than 80 percent of samples derived from patients with pancreatic, prostate and gastric cancers.