High Efficacy and Significantly Shortened Neutropenia Of Dose-Dense S-HAM As Compared To Standard Double Induction: First Results Of a Prospective Randomized Trial (AML-CG 2008)

For curative treatment of younger patients with acute myeloid leukemia (AML) double induction with two cycles of intensive cytarabine/ anthracycline based chemotherapy 21 days apart is the current standard of care. In the prospective randomized AML-CG 2008 trial we asked question whether current results could be improved on by a dose-dense regimen (S-HAM – Sequential High-dose cytArabine and Mitoxantrone) in which the interval between cycles was minimized to 3 days. A prior large one-armed study (AML-CG 2004) had demonstrated a high antileukemic efficacy and shortened neutropenia of the S-HAM regimen as compared to a historical control of standard double induction treatment. The first clinical results of the randomized comparison are presented here.

All patients with first diagnosis of a de-novo or secondary AML (excluding APL) that were deemed fit for intensive induction chemotherapy by their treating physician were eligible for this study. Younger patients in the standard arm were treated with one cycle of TAD-9 (standard dose cytarabine and daunorubicine 60mg/m² for 3 days) and a mandatory second cycle of HAM (high dose cytarabine and mitoxantrone) starting at day 21. Elderly patients were treated with one cycle of HAM followed by a second cycle of HAM only in case of residual leukemia in the day 16 bone marrow aspirate. Patients in the experimental arm all received S-HAM (two sequential cycles of high-dose cytarabine on days 1+2, mitoxantrone days 3+4) with a 3 days interval. Patients in the age cohort 60 – 69 could be allocated to the “younger” or “elderly” cohort according to their biological fitness at the discretion of the treating physician. However high-dose cytarabine dosages were allocated according to chronological age with patients <60 years receiving 3g/m² cytarabine per dose and patients 60+ years receiving 1g/m². The primary endpoint was the overall response rate (i.e. CR + CR_irate), secondary endpoints were duration of critical neutropenia, overall survival amongst others. Postremission treatment consisted of recommended early allogeneic transplantation in high risk patients and conventional postremission treatment according to the AML-CG standard (one cycle of TAD-9 consolidation followed by up to 3 years of maintenance treatment) in patients with low risk disease.

396 patients were randomized into the study with an age range of 18 to 86 years (median 58). The 387 evaluable patients (184 standard, 203 experimental) were well balanced according to their clinical characteristics, cytogenetics, molecular genetics and overall risk profile. For the primary endpoint a higher ORR of 77% for S-HAM could be found as compared to 72% in the standard arm which was however not significant because a 15% difference had been postulated for the study. Non-hematological toxicities did not show any significant differences. However this was in clear contrast to hematological toxicities: Importantly the duration of critical neutropenia was highly significantly reduced by more than 2 weeks from 45 days (standard) to 29 days (S-HAM) counted from day 1 of treatment. Similarly critical thrombocytopenia was reduced by 13 days from 46 days to 33 days. The early death (ED) rate between both arms was identical between both arms. However a subgroup analysis demonstrated a significantly reduced ED rate in patients receiving 1g/m² S-HAM as compared to all other treatment groups. The respective ED rates for the various time intervals (always counted from day d1 of treatment) for the 1g/m²S-HAM group were as follows: Interval d1-14 1%, d1-30 3%, d1-60 5%, d1-90 10%. Data for overall survival will be available in November 2013.

The dose-dense induction regimen S-HAM was highly feasible in patients up to the 8^th age decade. The antileukemic efficacy was high with an ORR of 77% for the whole group of unselected patients. As compared to standard double induction dose-dense S-HAM reduced critical neutropenia by more than two weeks. Moreover the subgroup of patients receiving the 1g/m² S-HAM regimen experienced the lowest ED rate ever reported in the AML-CG trials. This underlines that in contrast to our general expectations the concept of dose-density is able to combine high antileukemic efficacy with significantly reduced haematological toxicity in AML, characterising this approach as first candidate for the next standard arm for future trials of the study group.

Lengfelder:TEVA/ Cephalon: Research Funding.