An antibody-drug conjugate (ADC) composed of STI-5171, a fully human monoclonal antibody targeting human cell surface glycoprotein and tumor-associated antigen (TAA) CD38, site-specifically conjugated, via a non-polyethylene glycol linker, to a monomethyl auristatin F (MMAF)-derived cytotoxic payload, with potential antineoplastic activity. Upon administration of anti-CD38 ADC STI-6129, the antibody moiety targets and binds to CD38 on tumor cells. Upon antibody/antigen binding and internalization, the MMAF derivative binds to and inhibits tubulin polymerization, which results in G2/M phase arrest and tumor cell apoptosis. CD38, a type II transmembrane glycoprotein, is present on various immune cells and hematologic malignancies; its expression has been correlated with poor prognosis.