Treatment Results In Acute Myeloid Leukemia Over a Time Period Of 20 Years: Analysis Of The German-Austrian Acute Myeloid Leukemia Study Group (AMLSG)

Overall survival (OS) in acute myeloid leukemia (AML) treated with intensive chemotherapy has improved over the last 20 year especially in younger adults (18-60 years) but still remains poor in older patients (>60 years) (Döhner et al. Blood 2010). The German-Austrian AMLSG performed controlled prospective treatment trials since 1993 starting with a risk-adapted approach (phase I, 1993-1997), followed by randomized and risk-adapted treatment strategies based on cytogenetic risk groups (phase II, 1997-2002); since 2003 addition of differentiating agents and HiDAC inhibitors to intensive induction therapy was evaluated (phase III, 2003-2007). Of note, until 2007 younger and older patients (> 60 years) were treated in separate protocols with significantly lower dosages of chemotherapy in older patients. Starting from 2008, risk-adapted therapies were replaced successively by a genotype-adapted approach and the artificial age cut-off at 60 years was abandoned (phase IV, 2008-2012).

To evaluate the outcome of adult AML patients within the different time periods.

The study included 4705 intensively treated adults (younger, n=3546; older, n=1159) with newly diagnosed AML enrolled on 11 AMLSG treatment trials between 1993 and 2012. Patients with acute promyelocytic leukemia were excluded. All patients received intensive induction and consolidation therapy. Analyzed outcome variables were first complete remission rates (CR1), relapse-free survival (RFS), survival after relapse (SAR) and OS. Analyses were performed according to age groups (18-60 vs. >60 yrs). In younger patients comparisons were performed for the 4 treatment phases (I-IV), whereas for older patients analyses were restricted to phase II-IV.

In younger patients CR rates did not improve over time (1993-2013) and varied between 72% and 77% (p=0.12), whereas early and hypoplastic (ED/HD) death rates significantly declined from 10% to 5% (p=0.0001). In older patients CR rates significantly improved over time from 44% to 50% between 1998 and 2007 to 67% after 2008 (p<0.0001); ED/HD rates gradually declined from 12% to 8%, but the difference was not statistically significant (p=0.17).

The proportion of younger patients receiving an allogeneic hematopoietic stem cell transplantation (alloHSCT) increased from 30% (15% in CR1) in phase I to 58% (29% in CR1) in phase III and remained there in phase IV with 53% (26% CR1), whereas the proportion of patients receiving an autologous HSCT constantly decreased from maximally 16% (15% in CR1) in phase II to 0.4% (0.2% in CR1) in phase IV; the proportion of older patients receiving an alloHSCT steadily increased from 4% (2% CR1) in phase II to 21% (12% CR1) in phase IV; autoHSCT was rarely performed. OS at 4 years in both age groups significantly improved (p<0.0001, each) from 41% to 56% and from 10% to 23% in younger and older patients, respectively. This beneficial effect on OS over time in younger patients was due to a better RFS (p=0.01) and SAR (p<0.0001), whereas in older patients no improvement in RFS (p=0.20) and only in trend for SAR (p=0.07) was noted. In cytogenetically high-risk patients, OS in younger (p=0.001) and in older (p=0.007) patients got better; in older patients mainly driven by increase in CR rates (p=0.001) and in younger patients by an improvement in RFS (p=0.02) and SAR (p=0.05). Nearly the same pattern was identified for cytogenetically intermediate risk patients with a better OS in younger (p<0.0001) and older patients (p=0.01) due to higher CR rates in older patients (p<0.0001), no improvement in RFS in both age groups and a significantly better SAR in younger patients (p=0.0002). In contrast, in low risk patients improvement in OS was only present in older patients (p=0.02), due to a better RFS in older patients (p=0.02) but without any progress in younger patients. Furthermore we performed two subgroup analyses in intermediate risk patients. In the subgroup of patients characterized by the genotype NPM1-mut/FLT3-ITDneg a significant better OS was present only in younger patients (p=0.03); in FLT3-ITD positive AML a better OS was seen in younger patients (p<0.0001) due to a better RFS (p=0.05) and SAR (p=0.01).

Based on the German-Austrian AMLSG experience the prognosis in younger and older AML patients has improved over time. In older patients this is mainly a result of higher CR rates and in younger patients of better RFS and SAR.

Schlenk:Celgene: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Chugai: Research Funding; Amgen: Research Funding; Novartis: Research Funding; Ambit: Honoraria. Off Label Use: Pomalidomide in Myelofibrosis. Greil:Novartis: Honoraria, Research Funding.