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The randomized, phase 3 ALFA-0701 trial showed that a reduced and fractionated dose of gemtuzumab ozogamicin added to standard front-line chemotherapy significantly improves event-free survival in adults with de novo acute myeloid leukemia. Here we report an independent review of event-free survival, final overall survival, and additional safety results from ALFA-0701. Patients (N=271) aged 50-70 years with de novo acute myeloid leukemia were randomized to receive conventional front-line induction chemotherapy (3+7 daunorubicin+cytarabine) with/without gemtuzumab ozogamicin 3 mg/m2 on days 1, 4, and 7 during induction. Patients in remission following induction therapy received 2 courses of consolidation therapy (daunorubicin+cytarabine) with/without gemtuzumab ozogamicin (3 mg/2;/day on day 1) according to their initial randomization. The primary endpoint was investigator-assessed event-free survival. Secondary endpoints included overall survival and safety. A blinded independent review confirmed the investigator-assessed event-free survival results (August 1, 2011; hazard ratio, 0.66 [95% CI, 0.49-0.89]; 2-sided p=0.006), corresponding to a 34% reduction in risk of events in the gemtuzumab ozogamicin versus control arm. Final overall survival (April 30, 2013) favored gemtuzumab ozogamicin but was not significant. No differences were observed between arms in early death rate. The main toxicity associated with gemtuzumab ozogamicin was prolonged thrombocytopenia. Veno-occlusive disease (including after transplant) was observed in 6 patients in the gemtuzumab ozogamicin arm and 2 in the control arm. In conclusion, gemtuzumab ozogamicin added to standard intensive chemotherapy has a favorable benefit/risk ratio. These results expand front-line treatment options for adult patients with previously untreated acute myeloid leukemia. (ClinicalTrials.gov identifier: NCT00927498).

Pivotal phase II studies in acute myeloblastic leukemia (AML) patients in first relapse have used gemtuzumab ozogamicin (GO) (Mylotarg) at a dose of 9 mg/m 2 on days 1 and 14. These studies showed a 26% response rate (13% complete remission (CR) and 13% CRp (complete remission with incomplete platelet recovery)) but with high degree of hematological and liver toxicities. Based on in vitro studies showing a re-expression of CD33 antigenic sites on the cell surface of blasts cells after exposure to GO, we hypothesized that fractionated doses of GO may be efficient and better tolerated. Fifty-seven patients with AML in first relapse received GO at a dose of 3 mg/m 2 on days 1, 4 and 7 for one course. Fifteen patients (26%) achieved CR and four (7%) CRp. Remission rate correlated strongly with P-glycoprotein and MRP1 activities. The median relapse-free survival was 11 months, similar for CR or CRp patients. Median duration of neutropenia o500/ll and thrombocytopenia o50 000/ll were, respectively, 23 and 21 days. No grade 3 or 4 liver toxicity was observed. No veno-occlusive disease occurred after GO or after hematopoietic stem cell transplantation given after GO in seven patients. Mylotarg administered in fractionated doses demonstrated an excellent efficacy/safety profile.

Summary. Biphenotypic acute leukaemia (BAL) patients represented 8% of the 287 de novo consecutive adult acute leukaemias (23 BAL, 230 acute myeloid leukaemia (AML) and 34 acute lymphoblastic leukaemia (ALL)) referred to our department during the last 4-year period. Of these 23 BAL patients, 14 patients showed myeloid morphology and nine cases lymphoid morphology according to FAB criteria. There were no differences between lymphoid and myeloid BAL according to clinical and biological presentation and treatment outcome. We confirm the poor prognosis of BAL when compared to AML or ALL seen during the same period of time, in terms of complete remission (47%, 62% and 82% respectively, BAL v AML, NS and BAL v ALL, P ¼ 0·006) and 4-year overall survival (8·1%, 25·8% and 23·8% respectively, BAL v AML, P ¼ 0·05 and BAL v ALL, P ¼ 0·003). Comparing adult BAL patients with AML patients, we found an increase in poor prognostic factors: CD34 þ phenotype (82% v 60% respectively, P ¼ 0·03), unfavourable karyotype (60% v 20%, P < 0·0001) and Pgp over-expression by RT-PCR (0·705 v 0·107, P < 0·0001) and flow cytometry (0·824 v 0·391, P ¼ 0·0001). MRP and LRP were not found to be poor prognostic factors. Comparing BAL patients with ALL patients, we found also an increase in poor prognostic factors: age (51 v 39, P ¼ 0·003) and CD34 þ phenotype (82% v 50%, P ¼ 0·02). We conclude that BAL patients need a more aggressive treatment procedure, including high-dose AraC or the use of Pgp modulators for first-line therapy.

In acute myeloid leukaemia (AML) initiating pre-leukaemic lesions can be identified through three major hallmarks: their early occurrence in the clone, their persistence at relapse and their ability to initiate multilineage haematopoietic repopulation and leukaemia in vivo. Here we analyse the clonal composition of a series of AML through these characteristics. We find that not only DNMT3A mutations, but also TET2, ASXL1 mutations, core-binding factor and MLL translocations, as well as del(20q) mostly fulfil these criteria. When not eradicated by AML treatments, pre-leukaemic cells with these lesions can re-initiate the leukaemic process at various stages until relapse, with a time-dependent increase in clonal variegation. Based on the nature, order and association of lesions, we delineate recurrent genetic hierarchies of AML. Our data indicate that first lesions, variegation and treatment selection pressure govern the expansion and adaptive behaviour of the malignant clone, shaping AML in a time-dependent manner.

Purpose: Recently, a new ABC protein, breast cancer resistance protein (BCRP), was described. But its prognosis is not known in acute myeloid leukemia (AML). In addition, the prognosis of P-glycoprotein (Pgp) and BCRP in patients treated homogeneously by the same anthracycline (daunorubicin, idarubicin, or mitoxantrone) during all of the treatment with aracytine is not known. Therefore, we have evaluated the relationship between drug resistance phenotype, in vitro anthracene sensitivity, and the relation to treatment outcome.Experimental Design: We have analyzed 149 AML treated according to protocol of the European Organization for Research and Treatment of Cancer group. The prognostic value of BCRP and Pgp were analyzed in the whole population and according to intercalating agent.Results: BCRP was a prognostic factor, for achievement of complete remission (43% in positive patients and 69% in negative patients, P ‫؍‬ 0.005), the 4-year disease-free survival (12% versus 33%, P ‫؍‬ 0.03), and the 4-year overall survival (19% versus 38%, P ‫؍‬ 0.003). When BCRP expression and Pgp function were categorized in three groups, ؉/؉, ؉/؊ or ؊/؉, and ؊/؊, the achievement of complete remission was 45%, 66%, and 90% (P ‫؍‬ 0.0003), the 4-year disease-free survival was 8%, 26%, and 40% (P ‫؍‬ 0.01), and the 4-year overall survival was 16%, 37%, and 48% (P ‫؍‬ 0.001), respectively. Pgp function was a prognostic factor in patients treated by daunorubicin and idarubicin but not by mitoxantrone. In contrast, BCRP expression was a prognostic factor in patients treated by daunorubicin and mitoxantrone but not by idarubicin.Conclusions: BCRP would be implicated in the resistance to chemotherapies in AML. But these are the patients expressing both BCRP and Pgp who have the poorest prognosis.

Purpose: P-Glycoprotein (Pgp) is associated with poor outcome in acute myeloid leukemia (AML). We have investigated other ATP-binding cassette proteins such as BCRP, MRP1, MRP2, MRP3, and MRP5 for their potential implication in chemoresistance. Experimental Design and Results: Eighty five AML patient samples were analyzed in this study. First, MRP3 function was higher in patients which had a high level of leukocytes (P = 0.01), a M5 FAB subtype (P = 0.04), and an intermediate or poor cytogenesis (P = 0.05). BCRP activity was not correlated with clinical or biological variables, but high Pgp activity was correlated with the following variables: CD34 expression (P = 0.002), FAB subtype (P = 0.002), intermediate or poor cytogenesis (P = 0.02), and elderly patients (P = 0.03). Second, Pgp, MRP3, and BCRP activities were correlated with complete remission (P = 0.02, P = 0.04, and P = 0.04, respectively), disease-free survival (P = 0.02, P = 0.03, and P = 0.25, respectively), and overall survival (P = 0.04, P = 0.04, and P = 0.05, respectively) in multivariate analysis.The patient samples expressing one or none of these Pgp, MRP3, or BCRP functional proteins have a better prognosis than the patients expressing two or three of these functional proteins (complete remission, P = 0.02; disease-free survival, P = 0.01; overall survival, P < 0.001).Conclusions: BCRP and MRP3 may also be involved in chemoresistance in AML, especially MRP3 in patients with M5 FAB. Additional modulation of BCRP or MRP3 to Pgp modulation may be necessary in some patients in order to improve the treatment outcome.