High Remission Rates and Long-Term Survival in a High Percentage of Patients Achieved by Intensive Chemotherapy for AML and Further Improvement of Supportive Care.

Until recently, intensive chemotherapy for acute myeloid leukemia (AML) did not necessarily lead to high success rates, partly because of deaths from infections due to the associated long-term neutropenic phase. However, the advent of effective antifungal agents or the use of granulocyte colony-stimulating factor (G-CSF) or macrophage colony-stimulating factor (M-CSF) has definitely reduced deaths from chemotherapy and has improved the results of treatment with intensive chemotherapy also in elderly patients.

The complete remission rate after remission induction therapy and the event-free survival (EFS) after postremission therapy were investigated in 165 patients (99 men and 66 women) with untreated de novo AML (excluding subtype M3) who were consecutively registered in a single institution between March 2001 and March 2009. The patients' ages ranged from 16 to 94 years (median: 59 years). There were 3 patients with M0, 18 patients with M1, 25 patients with M2, 25 patients with t(8;21), 35 patients with M4, 12 patients with M4Eo, 35 patients with M5, 10 patients with M6, and 2 patients with M7.

Remission induction therapy consisted of 10 days of behenoyl-ara-C (BHAC) at 350 mg/m² (300 mg/m² for patients 70 years or older) and 4 days of idarubicin (IDA) at 12 mg/m² (10 mg/m² for 70 years or older). Further, if bone marrow examination revealed 5% or more residual blast cells on day 15, etoposide was additionally administered at a dose of 100 mg/m² for 4 days. The efficacy of the remission induction therapy was evaluated after 1 course of treatment. The patients who had achieved remission underwent 9 courses of postremission therapy, which lasted 11 months. The details are omitted, but therapy with high-dose (2 g/m² [1 g/m² for patients 60 years or older]) cytarabine (HDAC)×10 plus 7 mg/m² of mitoxantrone (MIT) ×3 was performed during the 1st and 9th courses. No HDAC was performed on the elderly aged above 75 years old. The intensive therapy with Aclarubicin (ACR) of 20 mg/body for 14 days and the maintenance therapy with a combination of BHAC 350 mg/m²×4 with ACR or IDA were repeated alternately every 6 weeks. Chemotherapies other than remission induction therapy and HDAC were performed in an outpatient clinic, and if the patients with the WBC decreasing to 1000/mm³ were hospitalized in the biological clean room. M-CS was administered for 7 days after the day following the end of chemotherapy, and subsequently G-CSF was administered until the WBC becomes to be 1000/mm³.

Complete remission (CR) was achieved in 143 of the 165 patients overall (86.7%), 113 of the 123 patients 69 years or younger (92.7%), and 29 of the 42 patients 70 years or older (69.1%). During the remission induction therapy, death occurred in 6 of the 165 patients overall (3.6%), 2 of the 123 patients 69 years or younger (1.6%), and 4 of the 42 patients 70 years or older (9.5%). The EFS in patients with CR was 61.5% at 8 years in patients 69 years or younger, while it was 26.9% at 5 years in patients 70 years or older. There was only a case of death due to chemotherapy during postremission therapy. Seven patients underwent bone marrow transplantation during the first remission, and 6 of these patients have been enjoying EFS.

Improvement in supportive care has enabled safe intensive chemotherapy. The patients with good or intermediate prognosis were clearly improved by the present preliminary treatment at a single institution, but the patients with poor prognosis still highly require bone marrow transplantation in the future.

No relevant conflicts of interest to declare.