Varying intensity of postremission therapy in acute myeloid leukemia

The Eastern Cooperative Oncology Group (ECOG) conducted a randomized trial in patients ≤65 years old (median, 44 years) to determine whether increasing the intensity of postremission therapy in acute myeloid leukemia (AML) would improve the outcome. After uniform induction therapy, patients in complete remission (CR) who were less than 41 years old and who had a histocompatible sibling underwent allogeneic bone marrow transplantation (alloBMT) (54 patients). The remainder of patients in CR were randomized to receive either 2 years of continuous outpatient maintenance therapy with cytarabine and 6-thioguanine (83 patients) or a single course of inpatient consolidation therapy consisting of 6 days of high-dose cytarabine plus 3 days of amsacrine (87 patients). The median duration of follow-up is now 4 years, and patients are included in the analyses of outcome regardless of whether they relapsed before starting the intended treatment. Four-year event-free survival (EFS) was 27% ± 10% for consolidation therapy versus 16% ± 8% for maintenance therapy (P = .068) and 28% ± 11% versus 15% ± 9% (P = .047) in patients less than 60 years old. The outcome for patients receiving alloBMT was compared with the subset of patients less than 41 years old who received consolidation therapy (N = 29) or maintenance therapy (N = 21). Four-year EFS was 42% ± 13% for alloBMT, 30% ± 17% for consolidation therapy, and 14% ± 15% for maintenance therapy. AlloBMT had a significantly better EFS (P = .013) than maintenance therapy, but was not different from consolidation therapy. In patients less than 41 years old, 4-year survival after alloBMT (42% ± 14%) did not differ from consolidation therapy (43% ± 18%), but both were significantly better than maintenance therapy (19% ± 17%), P = .047 and .043, respectively. The mortality rate for maintenance therapy was 0%, consolidation therapy, 21%; and alloBMT, 36%. Consolidation therapy caused an especially high mortality rate in the patients ≥60 years old (8 of 14 or 57%). The toxicity of combined high-dose cytarabine and amsacrine is unacceptable, especially in older patients, and alternative approaches to consolidation therapy such as high-dose cytarabine alone need to be tested. In AML, a single course of consolidation therapy or alloBMT after initial CR produces better results than lengthy maintenance therapy. Although EFS and survival of alloBMT and consolidation therapy do not differ significantly, a larger number of patients need to be studied before concluding that they are equivalent.