A highly lipophilic conjugate protein comprised of the lipophilic antitumor protein, neocarzinostatin (NCS), conjugated with a water-soluble copolymer of styrene-maleic acid (SMA) with potential antineoplastic activity. Upon intra-hepatic arterial administration, zinostatin stimalamer is deposited within tumor tissues, where the NCS moiety induces sequence-specific single and double-stranded breaks via free-radical based mechanisms, resulting in tumor cell death.