Experience with 2-chlorodeoxyadenosine in previously untreated children with newly diagnosed acute myeloid leukemia and myelodysplastic diseases

Purpose: To develop more effective chemotherapy regimens for childhood acut e myelagenous leukemia (AML). Patients and Methods: Between June 1991 and December 1996, we administered the nucleoside analog 2-chlorodeoxyadenosine (2-CDA) to 73 children with pr imary AML and 20 children with secondary AML or myelodysplastic syndrome (M DS). Patients received one or two 5-day courses of 2-CDA (8.9 mg/m(2)/d) gi ven by continuous infusion. All patients then received one to three courses of daunomycin, cytarabine, and etoposide (DAV) remission induction therapy . Results: Seventy-two patients with primary AML were assessable for response , their rate of complete remission (CR) was 24% after one course of 2-CDA, 40% after two courses of 2-CDA, and 78% after DAV therapy, Of the 57 patien ts who entered CR, 11 subsequently underwent allogeneic bone marrow transpl antation (BMT), and 40 underwent autologous BMT, Twenty-nine patients remai n in continuous CR after BMT. Two patients remain in CR after chemotherapy only. The 5-year event-free survival (EFS) estimate was 40% (SE = 0.080%). Patients with French-American-British (FAB) M5 AML had a higher rate of CR after treatment with 2-CDA (45% after one course and 70.6% after two course s) than did others (P = .002). In contrast, no patient with FAB My AML (n = 10) entered CR after treatment with 2-CDA, Similarly, no patient with prim ary MDS (9 = C) responded to 2-CDA. Seven patients with secondary AML or MD S (n = 14) had ct partial response to one course of 2-CDA, Conclusion: This agent was well tolerated, and its toxicity war acceptable. Future trials should examine the effectiveness of 2-CDA given in combinati on with other agents effective against AML.