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Summary Background Gemtuzumab Ozogamicin (GO) was the first example of antibody directed chemotherapy in cancer and developed for Acute Myeloid Leukaemia. Its role has been unclear. Five randomised trials where it was combined with standard induction chemotherapy in adults have produced different results. In an effort to clarify the level of benefit, if any, and in which patients outcomes might be improved, an individual patient data meta-analysis of these 5 trials has been undertaken. Methods All randomised trials of GO in adults (age >15), given in conjunction with the first course of intensive induction chemotherapy for AML (excluding APL) were identified. In a collaboration between the groups involved, source data concerning demographics, treatment was requested in May 2013 and collected in 3325 randomised patients (median age 58). All trials were centrally randomised and open-label, with survival as primary endpoint. Analyses are presented by standard techniques, and within standardised risk groups Results Remission rates were not increased, but by significantly reducing the risk of relapse overall survival at 5 years was improved irrespective of patient age (30.7% vs 34.6%; HR 0.90 (95% CI 0.82-0.98), p=0.01). The survival benefit was particularly clear in those with favourable cytogenetics (55.2% vs 76.3%; HR0.47 (0.31-0.73), p=0.0005), but also observed in intermediate risk patients (34.1% vs 39.4%; HR 0.84 (0.75-0.95), p=0.007) Patients with adverse karyotype did not benefit overall or within any trial. Dose levels of 3mg/m2 were associated with less toxicity and equal efficacy. Interpretation GO can be safely added to conventional induction therapy. For patients who do not have adverse cytogenetics there is a significant survival benefit. These data suggest that the use of GO should be re-evaluated and the license status of GO may need to be reviewed. Role of funding source There was no funder for this meta-analysis.

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The transcription factor C/EBP␣ is crucial for differentiation of mature granulocytes. Recently, different CEBPA gene mutations likely to induce differentiation arrest have been described in nearly 10% of patients with acute myeloid leukemia (AML). In the present study, we retrospectively analyzed the prognostic signifi-

Whether cancer is maintained by a small number of stem cells or is composed of proliferating cells with approximate phenotypic equivalency is a central question in cancer biology. In the stem cell hypothesis, relapse after treatment may occur by failure to eradicate cancer stem cells. Chronic myeloid leukaemia (CML) is quintessential to this hypothesis. CML is a myeloproliferative disorder that results from dysregulated tyrosine kinase activity of the fusion oncoprotein BCR-ABL. During the chronic phase, this sole genetic abnormality (chromosomal translocation Ph(+): t(9;22)(q34;q11)) at the stem cell level causes increased proliferation of myeloid cells without loss of their capacity to differentiate. Without treatment, most patients progress to the blast phase when additional oncogenic mutations result in a fatal acute leukaemia made of proliferating immature cells. Imatinib mesylate and other tyrosine kinase inhibitors (TKIs) that target the kinase activity of BCR-ABL have improved patient survival markedly. However, fewer than 10% of patients reach the stage of complete molecular response (CMR), defined as the point when BCR-ABL transcripts become undetectable in blood cells. Failure to reach CMR results from the inability of TKIs to eradicate quiescent CML leukaemia stem cells (LSCs). Here we show that the residual CML LSC pool can be gradually purged by the glitazones, antidiabetic drugs that are agonists of peroxisome proliferator-activated receptor-γ (PPARγ). We found that activation of PPARγ by the glitazones decreases expression of STAT5 and its downstream targets HIF2α and CITED2, which are key guardians of the quiescence and stemness of CML LSCs. When pioglitazone was given temporarily to three CML patients in chronic residual disease in spite of continuous treatment with imatinib, all of them achieved sustained CMR, up to 4.7 years after withdrawal of pioglitazone. This suggests that clinically relevant cancer eradication may become a generally attainable goal by combination therapy that erodes the cancer stem cell pool.

PURPOSE In patients with acute myeloid leukemia (AML), induction chemotherapy is based on standard doses of anthracyclines and cytarabine. High doses of cytarabine have been reported as being too toxic for patients older than age 50 years, but few studies have evaluated intensified doses of anthracyclines. PATIENTS AND METHODS In this randomized Acute Leukemia French Association 9801 (ALFA-9801) study, high doses of daunorubicin (DNR; 80 mg/m(2)/d x 3 days) or idarubicin (IDA4; 12 mg/m(2)/d x 4 days) were compared with standard doses of idarubicin (IDA3; 12 mg/m(2)/d x 3 days) for remission induction in patients age 50 to 70 years, with an event-free survival (EFS) end point. After two consolidation courses based on intermediate doses of cytarabine, patients in continuous remission were randomly assigned to receive or not receive maintenance therapy with recombinant interleukin-2 (rIL-2; 5 x 10(6) U/m(2) x 5 days each month) for a total duration of 12 months. A total of 468 patients entered the study (median age, 60 years). Results Overall complete remission rate was 77% with significant differences among the three randomization arms (83%, 78%, and 70% in the IDA3, IDA4, and DNR arms, respectively; P = .04). However, no significant differences were observed in relapse incidence, EFS, or overall survival among the three arms. In the 161 patients randomly assigned for maintenance therapy, no difference in outcome was observed between the rIL-2 and the no further treatment arms. CONCLUSION Neither intensification of anthracycline doses nor maintenance with rIL-2 showed a significant impact on AML course, at least as scheduled in this trial.

Acute promyelocytic leukemia (APL) is highly curable with the combination of alltrans retinoic acid (ATRA) and anthracyclinebased chemotherapy (CT), but very longterm results of this treatment, when CT should be added to ATRA and the role of maintenance treatment, remain uncertain. In our APL93 trial that included 576 newly diagnosed APL patients, with a median follow-up of 10 years, 10-year survival was 77%. Maintenance treatment significantly reduced 10-year cumulative incidence of relapses, from 43.2% to 33%, 23.4%, and 13.4% with no maintenance, maintenance using intermittent ATRA, continuous 6 mercaptopurine plus methotrexate, and both treatments, respectively (P < .001). Maintenance particularly benefited patients with white blood cell (WBC) count higher than 5 ؋ 10 9 /L (5000/L). Early addition of CT to ATRA significantly improved 10-year event-free survival (EFS), but without significant effect on overall survival (OS). The 10-year cumulative incidence of deaths in complete response (CR), resulting mainly from myelosuppression, was 5.7%, 15.4%, and 21.7% in patients younger than 55, 55 to 65, and older than 65 years, respectively, supporting the need for less myelosuppressive treatments, particularly for consolidation therapy. This study is registered at http:// clinicaltrials.gov as NCT00599937. (Blood.