Biological Properties of Vincaleukoblastine, an Alkaloid

Some biological effects of a new alkaloid, Vincaleukoblastine (VLB), are described. In mice bearing the t ransplantable leukemias LI~10, P1534, and AKr or Ehrlieh ascites tumor, t rea tment with VLB effectively prolonged survival. The effectiveness of t r ea tment depended on the amount and spacing of dosage and the time of the institution of t rea tment after t ransplantat ion. A single injection of VLB was highly active, but hourly doses were probably the most effective. VLB was also active when incubated with tumor cells. Transplanted or spontaneous m a m m a r y tumors in C3H mice also showed a reduced growth during t rea tment with VLB. Mice "cured" of AKr or P1534 t ransplanted leukemia by t r ea tment with VLB were subsequently resistant to repeated challenges by the tumor. AN mice, so treated, have to date not developed spontaneous leukemia. Fischer rats bearing t ransplanted IRC 741 leukemia also responded to VLB treatment . Circulating tumor cells were part icularly affected. VLB did not inhibit regeneration of the liver of the part ial ly hepatectomized rat. Bone marrow depression was striking, al though megakaryoeytes were little affected. Intestinal lesions were absent. The mouse tolerated greater doses of VLB than did the ra t or the guinea pig.