Biological response modifiers: their possibilities for cancer treatment

Immunotherapy with the so-called 'Biological Response Modifiers' is based on the concept that the immune system can be activated to control neoplastic growth. Immunotherapy gained popularity as a treatment in the 1960's because of data from experimental tumor models. This indicated that mainly nonspecific stimulation with products of bacterial or fungal origine could prevent recurrence of, or delay growth of experimentally transplanted tumors. Since immunotherapy was most effective against relatively small tumors, clinical investigators began to view it mainly as a post-surgical treatment for a inhibition of micrometastasis. Mainly the activation of the non specific killer cells, macrophages and lymphocytes seems very promising to target an immune stimulant in the tumor site with a relatively high specificity. In the present study a whole series of biological polymers were tested in view of their capacity to enhance the immune system. However, the relatively small number of such compounds which can be applied therapeutically demonstrates that the ability of a compound to stimulate the immune systems is dependent on several conditions, such as the molecular dimension, the structure type and the solubility criteria. It will be shown that specific fungal glucans are very promising candidates for a successful cancer treatment.