Outcome of First Salvage Therapy in Core Binding Factor Associated Acute Myelogenous Leukemia Is Less Than Optimal

Background: Core binding factor (CBF) associated acute myelogenous leukemia (AML) is considered to have a better prognosis compared to that of other patients with AML. Reinduction with cytarabine based therapy followed by allogeneic stem cell transplant is a standard salvage approach.

Method: We performed a retrospective analysis of outcome in patients with CBF AML.

Results: Between the years 1992 and 2005, 107 patients with CBF AML were treated at M.D. Anderson Cancer Center. Sixty-six (62%) patients had inv 16 abnormality and 41 (38%) had t(8;21) abnormality. Induction chemotherapy regimens included fludarabine and cytarabine with or without granulocyte colony stimulating factor (G-CSF) (66 patients) or idarubicin and cytarabine with/without G-CSF (41 patients). One hundred and one (94%) patients achieved complete remission (CR). After a median CR duration of 159 weeks, 37 (37%) patients relapsed. Relapse rate was 26/66 (39%) among patients with inv 16 abnormality and 11/41 (27%) among those with t (8;21) abnormality. Higher WBC count predicted for relapse (p=.001) and relapse rate did not differ among induction regimens (p=0.1).

Salvage chemotherapy included cytarabine based regimen in 22 (59%) patients, clofarabine and idarubicin (2 patients), topoisomerase inhibitor (5 patients), histone deacetylase inhibitor (2 patients) and miscellaneous regimens (6 patients). Sixteen (43%) of the patients with relapsed CBF AML achieved CR after first salvage therapy. Eleven of 26 (42%) patients with inv 16 and 7/11 (64%) of patients with t (8;21) were resistant to first salvage therapy. Thirteen patients (10 in CR) underwent allogeneic stem cell transplant and 12 of them remained in CR post-transplant. Overall survival was significantly worse among patients who relapsed compared to the ones who did not (p=.001).

Conclusion: A significant proportion of patients with CBF AML relapse and second remissions can be achieved in less than half the patients. This highlights the need for better induction/consolidation regimens in this group of patients with ‘good-risk’ AML.