Effect of fludarabine, cytarabine, filgrastim, and gemtuzumab ozogamicin (FLAG-GO) on relapse-free survival in patients with newly diagnosed core-binding factor acute myelogenous leukemia.

Abstract

6528 Background: Prior modulation with fludarabine increases cytarabine-triphosphate (ara-CTP) accumulation and granulocyte-colony-stimulating factor (G-CSF) increases the fludarabine-triphosphate (F-ara-ATP) levels in leukemic blasts. Our front-line regimen of fludarabine, cytarabine and filgrastim (FLAG) based on this rationale showed improved event-free survival compared to anthracycline and cytarabine based regimens in patients (pts) with core-binding factor acute myelogenous leukemia (CBF-AML). Medical Research Council AML 15 trial reported survival benefit from addition of gemtuzumab ozogamicin (GO) to chemotherapy regimens in patients with favorable-risk cytogenetics AML. Methods: In a clinical trial combining GO (3 mg/m2 IV) with FLAG (FLAG-GO) in newly diagnosed CBF-AML, pts received GO on day 1 of induction and of post-remission cycles 2 or 3 and 5 or 6 in addition to FLAG. FLAG regimen was comprised of fludarabine 30 mg/m2 and cytarabine 2 gm/m2 IV daily (both for 5 days in induction and 3-4 days in post-remission cycles) with filgrastim started on day-1 and continued till neutrophil recovery. Pts who received one non-FLAG-GO induction could enroll irrespective of their remission status. Results: Fifty pts [30 with t(8;21) and 20 with Inv16] have been enrolled [5 of 50 (10%) were in remission at enrollment from prior induction]. Median age is 48 years (range, 19-76), median WBC count 12.3 x106/L (range, 1.3-97.2); 12 patients (24%) were >60 years of age and frequency of kit mutation is 8%. Complete remission with or without platelet recovery (CR/CRp) was achieved in 43/45 (96%) pts with 2 deaths in induction. With 6 planned consolidations, the median number of consolidation treatments received is 5 (range, 0-6). Two-thirds of pts needed dose reduction during post-remission cycles. Seven (14%) pts [t(8;21)= 5, Inv 16=2] relapsed and with a median follow-up of 34 months (range, 15-54 months) the relapse-free survival rate is 83%. Conclusions: FLAG-GO is a highly effective regimen and has resulted in high rate of relapse-free survival in pts with newly diagnosed CBF AML.