Combined cyclophosphamide chemotherapy and maltose tetrapalmitate immunotherapy in the treatment of transplanted bladder and prostate carcinoma of the rat.

Chemoimmunotherapy in two animal models for urological cancers was studied. The models were Dunning R3327A prostatic carcinoma transplanted s.c. in Fischer X Copenhagen F1 hybrids and a well-differentiated bladder carcinoma transplanted orthotopically in the bladder submucosa of female Fischer rats. Cyclophosphamide, cis-platinum, and Adriamycin were initially used as anticancer chemotherapeutic agents, and the most effective ones were used in combination with maltose tetrapalmitate (MTP), which was used as an immunopotentiator. In the case of prostatic carcinoma, cyclophosphamide was the most effective among the anticancer agents in controlling tumor growth after inoculation of either 10(4) or 10(5) tumor cells. Combination of cyclophosphamide with i.p. MTP delayed tumor take and controlled tumor size more effectively than did either of the treatments given alone. Similar results were obtained in the case of bladder tumor. A combination of cis-platinum with MTP significantly controlled bladder tumor size, and a combination of cyclophosphamide with MTP cured 75% of the rats. The remaining 25% of this group had a small tumor that did not increase in size during the subsequent 2 weeks of observation without treatment. The incidence of metastasis of bladder tumor to lymph nodes and lung was reduced by MTP and cis-platinum and eliminated by cyclophosphamide alone and in combination with MTP. Nonspecific immunity as measured by phytohemagglutinin stimulation of spleen lymphocytes and antitumor immunity as measured by cytotoxicity and macrophage migration inhibition assays were highest in rats subjected to cyclophosphamide and MTP combined therapies.