Amonafide and ara-C treatment for secondary acute myeloid leukemia (sAML)

Abstract

7065 Background: sAML portends a poor prognosis due to disease (unfavorable cytogenetics and multidrug resistance (MDR) phenotype) and patient (pt) characteristics (elderly w/comorbid illnesses). Amonafide, a topoisomerase II inhibitor, is not a substrate for the MDR efflux pump, P-glycoprotein (see Chau et al, ASCO 2007). Phase 1 trials of amonafide alone or together with ara-C reported a 50% CR rate (10/20) in pts with sAML (Allen et al, ASCO 2006). The dose-limiting toxicities of amonafide were manageable. Methods: In a Phase II trial pts with sAML (prior MDS or leukemogenic therapy, i.e., tAML) received amonafide 600 mg/m2/day on days 1–5 and CIV ara- C 200 mg/m2/day on days 1–7. A 2nd course could be given if day 14 marrow showed persistent leukemia. CR pts received either stem cell transplant or intermediate/high dose ara-C depending on age. An independent Data Safety Monitoring Board and central morphology review participated in the study. Primary endpoint was CR rate. Results: Enrollment has been completed. 44 % of 80 pts achieved CR. Details are available for the 1st 40 pts: median age 63 yrs (range 26 –87); prior MDS, 57%; tAML, 43%; unfavorable cytogenetics, 40%. 16/40 (40%) achieved CR (15 CR+1CRp). Subgroup CR analysis: MDS→AML without and with prior therapy for MDS (mostly azacytidine), 64% & 33%; tAML, 29%; intermediate and unfavorable cytogenetics, 58% and 18%; <60yrs, 42%; ≥60yrs, 39%. With a median follow up of 39 weeks, the median duration of CR is 28 weeks (range 20+ to 40+ weeks), with 8 of 16 patients in continuous CR. Median overall survival for CR patients has not been reached (range 1–47+ weeks). Death in first 28 days from consequences of hypoplasia was 17.5%. Grade 3, 4 non-heme adverse events occurring in > 10% pts were hypotension 23%, pneumonia 18%, dyspnea 13%, and diarrhea 13%. Data on all patients will be updated. Conclusions: Amonafide and ara-C is well tolerated in patients with poor prognosis sAML. A 64% CR was achieved in pts with untreated MDS→AML. Lower CR occurred with prior therapy for MDS, tAML and unfavorable cytogenetics. Age ≥60 yrs did not affect CR. Amonafide and ara-C may be a promising alternative for patients with sAML, especially those with over-expression of P-glycoprotein. No significant financial relationships to disclose.