An antibody-drug conjugate (ADC) containing an antibody (SC16) directed against an as of yet undisclosed protein and conjugated to the cytotoxic agent D6.5, with potential antineoplastic activity. Upon administration, the antibody moiety of rovalpituzumab tesirine selectively binds to the target on tumor cell surfaces. Upon internalization, the D6.5 moiety is released and causes DNA damage, which may result in the inhibition of proliferation of tumor cells that overexpress this target.