Etoposide (VP-16) with prednisone and vincristine for the treatment of refractory acute lymphoblastic leukemia.

Fifty children with acute lymphoblastic leukemia (ALL) in first to fifth relapse were treated with a three-drug reinduction regimen consisting of prednisone (40 mg/m2/d for seven days), vincristine (1.5 mg/m2 on day 1) and etoposide (VP-16, 250 mg/m2 on days 1 through 3). The intent was to assess the efficacy of VP-16 in an otherwise conventional reinduction plan, especially in patients who had previously received teniposide (VM-26), the close congener of VP-16. Among the 46 patients who received at least two courses of the therapy, 16 (0.34) achieved complete remission. Seven others showed improvement in their bone marrow status. Each child had been heavily pretreated with prednisone and vincristine, and 14 had received VM-26. That seven patients judged to be clinically resistant to VM-26 had complete responses to prednisone-vincristine-VP-16 indicates that prior treatment with one podophyllotoxin derivative does not preclude responses to the other. We are uncertain about the pharmacologic basis of these results but suggest that the increased dosage and more frequent administration of VP-16, relative to that of VM-26, was sufficient to overcome apparent resistance to the latter compound. Remission durations ranged from one to eight months (median, four months), emphasizing the need to devise more effective continuation therapy, including investigational agents such as the epipodophyllotoxins.