Biotherapy: the fourth modality of cancer treatment.

Biotherapy represents a new modality of cancer treatment. It utilizes biologicals and biological response modifiers in the treatment of cancer. Many of these substances are of "natural" origin emanating from mammalian cells as physiologic mediators of immune response and as substances active in the regulation of growth and maturation. With the advent of molecular biological techniques, hybridoma technology, and computer applications, it is now possible to prepare these biological substances in highly purified form and in large quantities for use as medicinals. The expertise required to apply these biotherapeutic approaches to the treatment of cancer often involves the use of immunological and/or molecular biological capabilities. Because of the rather specialized expertise needed to understand and apply these substances as anticancer approaches, those individuals with expertise in the application of chemotherapy to patients with cancer are not necessarily well prepared for the translation of biotherapy to the clinic. Biotherapeutic approaches are broad and involve a whole range of physiological responses inherent in cancer biology. The approaches necessary to bring these biotherapeutic capabilities to the clinic need to be considered carefully, and the use of new techniques and new methods of application should be encouraged so as not to inhibit these potentially powerful anticancer approaches. As natural mediators, many biologicals have much less inherent toxicity than the drugs previously used in systemic cancer therapy. Therefore, the systems for translating these substances from the laboratory to the clinic should be restructured for the rapid translation of biotherapy to the patient.