Rationales for combining chemotherapy and biotherapy in the treatment of cancer.

Chemotherapy and biotherapy are the two systemic modalities available for cancer treatment. In vitro assays and animal studies suggest various rationales for combining these two modalities. The first approach is to take advantage of apparent additive or synergistic cytotoxic and/or cytostatic effects of both modalities. A second approach is the use of chemotherapy to maximally cytoreduce tumor, followed by biotherapy to restore the immune system and/or to enhance immunologic elimination of microscopic tumor. The third approach uses biotherapy to diminish chemotherapy toxicities so that higher and more intense doses of chemotherapy can be used. The fourth approach involves the use of biologics to modify the tumor environment in order to enhance the delivery of chemotherapy molecules. A fifth approach is the use of chemotherapy as a biologic response modifier to enhance antitumor effects of biotherapy. The sixth strategy is to use biologics to reduce or overcome cell resistance to chemotherapy. Clinical trials are in progress exploring these various strategies. The end point of all of these approaches must be an improved risk to benefit or toxicity to efficacy ratio in the context of cancer treatment.