High Antileukemic Efficacy and Shortened Neutropenia of Dose-Dense Induction (Sequential-HAM Followed by Pegfilgrastim) in Primary Acute Myeloid Leukemia - Results of a Pilot Study of the German AML-CG.

Dose density during early induction has been demonstrated to be one of the prime determinants for antileukemic efficacy. The German AML-CG therefore pilots a dose dense induction regimen S-HAM (sequential HD-AraC [3g/m2/12h d1,2,8,9] and Mitoxantrone 10mg/m2 [d3,4,10,11] followed by pegfilgrastim) in which two induction cycles are applied over 11 – 12 days as compared to conventional double induction, in which two cycles are applied over 25 – 29 days - thereby increasing dose density ca. two-fold in the critical first weeks of treatment. In the past 2,5 years 168 patients with de-novo AML (excluding APL) have been recruited into the trial with a median age of 53 years (range 18 – 78). Of 136 patients evaluable for response the following results were achieved: CR 62%, CRi 22%, PL 7%, ED 9% - resulting in an overall response rate (ORR) of 84%. The early death rate (ED) of 9% and the toxicity profile compared favourably with a historical control group of the AML-CG 1999 study (de-novo AML, < 60 years, HAM-HAM double induction) which demonstrated an ED rate of 14% (ORR 68%, persistent leukemia (PL) 18%). The high antileukemic efficacy of S-HAM was also demonstrated by the fact that 89% of patients had a blast count of < 10% one week after therapy as compared to less than 48% of patients of the HAM-HAM double induction group. Whereas even for patients with unfavourable cytogenetics (including complex aberrations) a median overall survival of 13,5 months was reached (23% at 2 years), for patients with favourable karyotypes overall survival at 2 years was 81%and for patients with intermediate karyotypes 74% after S-HAM treatment. Importantly the compression of the two induction cycles into the first 11 – 12 days of treatment seems actually beneficial for normal hematopoesis as demonstrated by a significantly shortened duration of critical neutropenia of 30 days as compared to 45 days after conventionally timed double induction. This shortening of critical neutropenia by more than 2 weeks was highly relevant for the duration of hospital stay and hospital costs. In conclusion S-HAM with pegfilgrastim support is a highly effective regimen in primary de-novo AML with a very favourable safety profile and significantly shortened duration of neutropenia. This regimen will therefore constitute the (dose-dense) experimental arm for a randomized comparison with standard double induction in the next generation of the German AML-CG studies.