[Targeting of anthracyclines and hepatomas]

Abstract

DNR can be targeted to the liver by linking to galactosylated human serum albumin (AG). The linkage is stable in the blood stream and allows the release of active DNR after endocytosis of the conjugate by the target cells. Receptors for AG are present at the cell membrane of hepatocytes, primary human hepatoma cells and lung metastases. After i.v. administration of AG-DNR more than 70% of the drug is taken up by the liver and in rats 50% of DNR is eliminated in the bile after 16 h. Nude mice bearing human hepatoblastoma cells implanted s.c. were treated twice a week with a dose equivalent to 6.6 mg/kg of DNR either for the free drug or the conjugate AG-DNR. After 7 injections, tumor growth is inhibited in both case, however, the conjugate seems more active and is at least twice less toxic in terms of LD50. A phase I clinical trial of AG-DNR on 11 patients bearing hepatocarcinoma revealed that despite a transitory hyperthermia (37-38 degrees C) during the first day of the 4 day-perfusion, and modifications of hepatic enzymes in 3 cirrhotic patients, no hematologic and cardiac toxicity could be detected. A subjective response has been obtained in half of the patients with a decrease of plasmatic alpha-foetoprotein levels by more than 50% in 4 patients and one complete remission of more than 23 months with disparition of pulmonary metastases.