Priming with Granulocyte-Colony Stimulating Factor Did Not Improve Outcome in a Randomized Study of Elderly Acute Myeloid Leukemia but Increased Induction Mortality.

Introduction: In acute myeloid leukemia (AML), granulocyte-colony stimulating factor (G-CSF) has been used in combination with induction chemotherapy to improve complete remission rates (CR) by sensitization of leukemic cells. This randomized prospective oligocenter study was designed to assess whether two induction cycles given simultaneously with and followed by G-CSF (G-CSFpriming) was superior to G-CSF administered only after induction (G-CSFpost) with regard to CR and disease-free survival (DFS) in patients older than 60 years. Secondary objectives were comparison of this concept in de novo versus secondary AML and to examine the feasibility of autologous stem cell transplantation (ASCT) as late consolidation.

Methods: Overall, 183 eligible pts (median age 67 yrs) were randomly assigned to receive G-CSF starting on the day before (n=91) or after chemotherapy (n=92) during two induction cycles consisting of idarubicin, cytarabine and etoposide (IdAV). The two treatment groups were evenly matched with respect to age, diagnosis and cytogenetic risk factors. G-CSF was given as daily s.c. injection at 5μg/kg. Pts achieving a CR were scheduled to receive early consolidation chemotherapy with fludarabine, cytarabine, idarubicin plus G-CSF (mini-FlagIda) and peripheral blood stem cell (PBSC) harvest, followed by ASCT as late consolidation. Pts lacking PBSC due to mobilization failure were optionally treated with a second cycle of mini-FlagIda as late consolidation.

Results: After induction chemotherapy, 118 out of 183 pts (64%) achieved CR. Response was not different in the G-CSFpost vs. G-CSFpriming group (70% vs. 59%, p=0.148). Recovery of neutrophils was similar in both groups after cycle 1 (21.8 vs. 20.5 days) and cycle 2 (14.9 vs. 16.3 days). Notably, G-CSF priming resulted in a significantly increased mortality in induction 1 (25% vs. 9%, p=0.003) associated with a higher rate of severe mucositis and infectious complications. The probability of OS and DFS at 5 years was 16% and 20%, resp., with no significant differences between the induction groups. With a median follow up of 26 months (range, 5–77), 77 out of 118 complete responders have relapsed and 7 died while in CR. Patients with de novo AML had a significantly better OS than those with secondary AML (17 vs. 11 months, p<0.001). Unfavorable cytogenetics were associated with a poor median OS (7 vs. 15 months, p<0.001). Following mini-FlagIda I, collection of at least 2x10E6 CD34+ PBSC/kg was feasible in 35 of 67 pts in whom mobilization of CD34+ cells was monitored. Late consolidation with ASCT (n=19) was not superior to mini-FlagIda II (n=16, DFS 24 vs. 27 months).

Conclusions: In this randomized study with elderly AML patients, G-CSF priming did not result in an increased CR rate and was associated with higher induction mortality, but OS was not influenced. We demonstrated feasibility of ASCT in patients up to the age of 70 years, which was not superior to chemotherapy consolidation.