Biochemical effects of the Vinca alkaloids. IV. Studies with vinleurosine

Vincristine and vinblastine lower plasma cholesterol concentrations in rhesus monkeys

3-4 days after a single clinical dose of vincristine or vinblastine in rhesus monkeys there was a marked decrease in plasma low-density lipoprotein cholesterol concentrations. There was also a concomitant increase in plasma triacylglycerol concentrations. Plasma lipid levels returned to normal concentrations within 7-10 days after injection. Plasma high-density lipoprotein cholesterol concentrations were unaltered by the drugs. Electron micrographs of the hepatocytes from monkeys treated with vincristine or vinblastine showed an accumulation of glycogen particles and proliferation of smooth endoplasmic reticulum, which was accompanied by an increase in the number of lipoprotein-containing vesicles. These results indicate that vincristine and vinblastine alter plasma cholesterol and triacylglycerol concentrations in part by interfering with hepatic lipid and lipoprotein metabolism. These studies further suggest the possibility that other less cytotoxic alkaloids from Catharanthus species with clinically useful hypocholesterolemic activity may be discovered.

Response to vincristine of recurrent brain tumors in children

Seventeen children with clinical evidence of a recurrent brain tumor were treated with vincristine 1.5 mg/sq m weekly for 12 weeks with doses on alternate weeks thereafter. Eight of the 16 patients who received four or more doses of vincristine showed significant objective responses; these included patients with high-and low-grade astrocytomas and patients with medulloblastoma. Six of the eight who responded remained asymptomatic for more than 2 years. The toxicity encountered was minimal except for seizures possibly related to vincristine in three children, who were able to resume treatment. Vincristine therapy results in long-term regression in a wide variety of pediatric brain tumors and causes little or no toxicity.