Use of oily contrast medium for selective drug targeting to tumor: enhanced therapeutic effect and X-ray image

Highly malignant rabbit tumor (VX-2) was implanted in the liver in 63 rabbits. Selective delivery of the anticancer agent copoly(styrenemaleic acid) conjugated to neocarzinostatin (SMANCS) was performed by injection via the proper hepatic artery. By using low-kVp X-ray examination of the resected liver, Lipiodol was found to distribute through the entire liver arterial lumina and was retained for about 24 hr, but disappeared gradually. However, Lipiodol was retained in the tumor tissue and vessels for at least 7 days. A radioactive analogue of Lipiodol, was prepared by using [14C]linoleic acid. This analogue was used in the study of the distribution by low-kVp X-ray examination, Sudan III staining, and autoradiography. Lipiodol remained in the tumor vessels as well as the tumor cells. The use of the radioisotope yielded a quantitative profile of Lipiodol accumulation in tumor tissues. Its major excretion route appeared to be through the bile. The biological activity of SMANCS was also determined in both tumor and liver, no activity was found in other organs. The relatively high biological activity of SMANCS in the nontumorous liver adjacent to the tumor may be the result of continuous drug release from SMANCS-Lipiodol in the tumor tissue