A prodrug is a compound with low or no pharmaceutical activity which is metabolized after administering to the active drug. Prodrug activation in many cases is achieved by enzyme-mediated processes. A variety of publications deals with the development of prodrugs for application in antibody-directed enzyme prodrug therapy for cancer treatment. Enzymes that activate prodrugs belong to the classes transferases, hydrolases including proteases, lyases, and oxidoreductases; they are mostly of endogenous origin. The virus-directed enzyme prodrug therapy has been used among others for selective activation of prodrugs in tumor tissues by exogenous enzymes for cancer therapy. Future perspectives in enzyme prodrug therapy applied in targeted cancer treatment and based on aberrant cancer specific markers focus on improvements of these strategies to enhance the number of successful clinical trials and approvals. Engineered polymer drug conjugates used together with chemotherapy treatments serve to overcome the limitations of traditional chemotherapy.