A plasmid DNA encoding an inactivated form of the carcinogen activator cytochrome P450 1B1 (CYP1B1) encapsulated in biodegradable poly-DL-lactide-coglycolide microparticles with potential antineoplastic activity. Vaccination with ZYC300 may stimulate the immune system to elicit a cytotoxic T lymphocyte (CTL) response against the tumor-associated antigen (TAA) CYP1B1, which may result in the lysis of tumor cells expressing CYP1B1. CYP1B1, an extrahepatic monooxygenase of the cytochrome P450 family, is overexpressed in many cancers with only restricted expression in normal tissues.