Site-specific delivery of cytokines in cancer

Cytokines can stimulate the immune response by directly activating effector cells and/or by inducing the release of secondary cytostatic or immunomodulatory molecules. Systemic administration of cytokines, however, often causes numerous side effects in the patient and may not provide a constant level at the tumor site, owing to the variable and generally short half-lifes of cytokines. This has led to the development of novel strategies to deliver cytokines specifically to tumor sites in vivo. These include: the use of monoclonal antibodies directed against tumor antigens; cellular vehicles designed to carry genes to tumor sites; genetically engineered tumor cell vaccines; and targetable viral vectors.