Cancer biotherapy: general principles

The term biotherapy encompasses the therapeutic use of any biological substance, but more specifically it connotes the use of products of the mammalian genome. With modern techniques of genetic engineering, the mammalian genome represents the new ‘medicine cabinet.’ Biological response modifiers (BRM) are agents and approaches whose mechanisms of action involve the individual’s own biological responses. Biologicals and BRM work through diverse mechanisms in the biotherapy of cancer. They may (a) augment the host’s defenses through the administration of cells, natural biologicals, or the synthetic derivatives thereof as effectors or mediators (direct or indirect) of an antitumor response; (b) increase the individual’s antitumor responses through augmentation or restoration of effector mechanisms, or decrease a component of the host’s reaction that is deleterious; (c) augment the individual’s responses using modified tumor cells or vaccines to stimulate a greater response, or increase tumor cell sensitivity to an existing biological response; (d) decrease transformation and/or increase differentiation or maturation of tumor cells; (e) interfere with growth-promoting factors produced by tumor cells; (f) decrease or arrest the tendency of tumor cells to metastasize to other sites; (g) increase the ability of the patient to tolerate damage by cytotoxic modalities of cancer treatment; and/or (h) use biological molecules to target and bind to cancer cells and induce more effective cytostatic or cytocidial antitumor activity.