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The primary objective of this trial was to assess the feasibility, toxicity profile, and antitumor activity of gemtuzumab ozogamicin (GO) combined with a chemotherapy remission-induction regimen in adults with untreated high-risk myelodysplastic syndrome (HR-MDS) or secondary acute myeloid leukemia (sAML). In this phase II trial, 30 patients with median age of 58 years received 1 day of GO as a 1-h infusion at the dose level of 5 mg/m(2) on day 7 of the remission-induction course further consisting of a continuous infusion of cytarabine 100 mg/m(2)/day for 10 days and idarubicin 12 mg/m(2)/day on days 1, 3, and 5. A consolidation course, consisting of intermediate-dose cytarabine (A) and idarubicin (I) followed by hematopoietic stem cell transplantation (HSCT) was planned for patients in complete remission (CR). The primary endpoints were response rate (CR/CRi) and severe toxicity rate. The secondary endpoint(s) were survival and progression-free survival (PFS) from start of treatment. Thirteen patients (43 %) achieved CR (eight patients) or CR with incomplete hematopoietic recovery (CRi) (five patients). In patients who achieved CR or CRi, the median time to recovery of neutrophils to 0.5 × 10(9)/l and of platelets to >50 × 10(9)/l was 29 and 30 days, respectively. Grade 3 to 4 severe toxicities occurred in nine patients. The most prominent was liver toxicity, as shown by elevated bilirubin levels in 16 patients and one case of nonfatal veno-occlusive disease (VOD). All 13 patients with CR/CRi received consolidation therapy, which was followed by allogeneic HSCT in five patients and autologous HSCT in three patients. According to the statistical design of the study, the idarubicin and cytarabine in combination with gemtuzumab ozogamicin (IAGO) regimen did not show sufficient activity to warrant further exploration of this regimen in adult patients with HR-MDS or sAML. [ABSTRACT FROM AUTHOR]

High-risk myelodysplastic syndrome (MDS) patients have usually a less favorable outcome after intensive treatment compared with de novo acute myeloid leukemia (AML) patients. This may reflect different disease-related and patient-related factors. The purpose of this analysis is to identify disease-specific prognostic factors and to develop prognostic scores for both patient groups. A total of 692 patients in the EORTC/GIMEMA AML-10 study and 289 patients in the CRIANT study received identical remission-induction and consolidation treatment. Estimated 5-year survival rate was 34 % in the AML-10 versus 27 % in the CRIANT study, and estimated disease-free survival was 40 % versus 28 %, respectively. In multivariate analysis, cytogenetic characteristics, white blood count, and age appeared prognostic for survival in both studies. French-American-British (FAB) subtype and performance status were prognostic in the AML-10 study only, whereas number of cytopenias and duration of antecedent hematologic disorder >6 months were prognostic in the CRIANT study only. The prognostic scores distinguish three groups with a 5-year survival rate of 54, 38, and 19 % in the AML-10 study versus 69, 37, and 5 % in the CRIANT study. The prognostic value of these scores has been validated on two external series. The new scoring systems form a practical tool to predict the outcome of individual MDS and AML patients treated with intensive antileukemic therapy. [ABSTRACT FROM AUTHOR]

Abstract: Resistance to cytarabine (AraC) is a major problem in treatment of patients with acute myeloid leukemia (AML). In contrast to in vitro AraC resistance, deoxycytidine kinase (dCK) mutations are rarely found in patients with refractory or relapsed AML. Previously we have demonstrated alternatively spliced dCK mRNA predominantly expressed in leukemic blasts from patients with resistant AML. In this study we investigated wild-type (wt) dCK expression and activity to elucidate the possible role of decreased dCK expression or activity in unresponsiveness to AraC in patients with AML. No alterations in dCK mRNA and protein expression or in dCK activity were detected between patients with clinically resistant vs. sensitive AML. In addition, wt dCK expression and activity were not reduced in leukemic blasts expressing alternatively spliced dCK forms as compared to blasts with only wt dCK. Also, no major differences in wt dCK expression and activity were observed between samples obtained from patients with AML and bone marrow or peripheral blood samples from healthy donors. These data implicate that in our patient group of refractory or relapsed AML cases, alterations in dCK expression and/or activity cannot explain unresponsiveness to chemotherapy including AraC. [ABSTRACT FROM AUTHOR]

Intensive chemotherapy regimens with or without stem cell transplantation are the current standard treatment in patients with acute myeloid leukemia (AML). The identification of new mutations in AML may provide the basis for a more targeted therapeutic approach. In one or several genetic subsets, some new drugs, as single drug or in combination with standard antileukemic drugs, demonstrated promising results. Typical examples are tyrosine kinase inhibitors, such as dasatinib for f c-Kit mutated core binding factor positive AML or FLT-3 inhibitors, such as midostaurin or sorafenib, in cases with FLT-3 mutations. Clofarabine is a second generation hybrid purine nucleoside analogue: standard induction regimens containing clofarabine provided a high remission rates in patients with intermediate and high risk AML. In patients unfit for intensive chemotherapy, treatment with hypomethilating agents is widely used. Gemtuzumab ozogamicin, anti-CD33 monoclonal antibody conjugated to calicheamicin, has shown significant antileukemic activity in older patients with relapsed AML. [ABSTRACT FROM AUTHOR]

AraC resistance in vitro is explained by inactivation of dCK, while resistance to DNR is described by overexpression of multidrug efflux pumps like Pgp or MRP. Thusfar, no correlation between resistance mechanisms in vitro and in patients with AML has been documented. We generated AraC and DNR double resistant cell lines to investigate resistance mechanisms of both agents. In these cell lines involvement of dCK was extensively investigated and Pgp expression and activity was determined. Our data implicate that similar resistance mechanisms like inactivation of dCK coincided by alternatively spliced dCK forms and overexpression of Pgp are induced in single—as well as in double resistant leukemic cell lines. [Copyright &y& Elsevier]