Yttrium-90 and iodine-131 radioimmunoglobulin therapy of an experimental human hepatoma.

Therapeutic trials were performed on the HepG2 human hepatoblastoma implanted s.c. in the athymic nude mouse. Animals were treated with polyclonal and monoclonal antiferritin and control antibodies labeled with either iodine-131 (131I) or yttrium-90 (90Y). Administration of 400 muCi of 131I-labeled polyclonal antiferritin or 300 muCi of 90Y-labeled polyclonal antiferritin significantly increased survival (P less than 0.001). There were no tumor cures with radiolabeled polyclonal antibody therapy. Animals treated with 200 or 300 muCi of 131I-labeled monoclonal antiferritin (QCI054) did not show increased survival compared to controls. Although 400 muCi of 131I-labeled QCI significantly prolonged survival, treatment resulted in no long-term survivors. Monoclonal antiferritin labeled with 90Y significantly prolonged survival of animals (P less than 0.001) at doses of 100, 200, or 300 muCi compared with untreated controls. Fifty % of the animals treated with 200 muCi and 75% of the animals treated with 300 muCi showed no evidence of disease at 140 days following treatment. Four hundred muCi of 90Y-labeled QCI proved toxic to the animals. Increased survival was accompanied by a decrease in tumor mitotic rate and increase in cellular polymorphism as determined by pathological examination. The radiation dose absorbed in the tumor correlated directly with tumor response following treatment. The absorbed dose in tumors for complete decay of the isotope ranged from 165 and 330 cGy at the periphery and center of small tumors for an administered activity of 200 muCi of 131I-labeled polyclonal antiferritin, to 7,573 and 12,400 cGy for 300 muCi of 90Y-labeled monoclonal antiferritin QCI.