Localized chemotherapy of Gardner's lymphosarcoma of C3H mice using combinations of carrier-sorbed antifolics and detoxicating tetrahydrofolates

The effect of aminohexyl-2-hydroxyethylmethacrylate polymer (HEMA-Hex) with sorbed methotrexate (MTX) or 3',5'-dibromoaminopterin (BrAP) on the survival of C3H mice with Gardner lymphosarcoma was studied. The measured bits of HEMA-Hex-MTX or HEMA-Hex-BrAP were implanted into the solid tumor growing 4 to 8 8 days. The doses of sorbed antimetabolites amounting in MTX 4.3 to 13.5 mg.kg-1 and in BrAP 5.1 and 12.6 mg.kg-1 were calculated from the area of the carrier and mean weight of Animals. Following implantation i. p. injections of leucovorin or anhydroleucovorin were applied. The treatment of early tumors showed better results than that of advanced ones if evaluated either as prolonged survival or as a number of mice surviving the observation period. The 18-hr. interval between implantation of HEMA-Hex-MTX and anhydroleucovorin injection was optimum if considered both the protection of mice from lethal MTX toxicity and therapeutic effect measured as prolonged survival. Doses of leucovorin or anhydroleucovorin close to MTX doses in term mg.kg-1 resulted in best results. In case leucovorin was applied to tumor-bearing mice pretreated with HEMA-Hex with nonlethal dose of MTX, the survival of mice was shortened. Folic acid did not show this effect. Intra-tumorous implantation of HEMA-Hex-BrAP toxicity even if applied into an advanced tumor. The therapeutic effect of the sorbed BrAP seemed to decrease with tumor progression at a lower rate than of that the sorbed MTX. The application of anhydroleucovorin after implantation of HEMA-Hex-BrAP shortened the survival of tumor-bearing mice.