Age-related risk profile and chemotherapy dose response in acute myeloid leukemia: a study by the German Acute Myeloid Leukemia Cooperative Group

Three novel cytogenetically cryptic EVI1 rearrangements associated with increased EVI1 expression and poor prognosis identified in 27 acute myeloid leukemia cases

In acute myeloid leukemia (AML), increased ecotropic virus integration site 1 protein homolog (EVI1) gene expression is prognostically unfavorable. Subsets of cases show 3q26 rearrangements, such as inv(3)(q21q26)/t(3;3)(q21;q26), frequently accompanied by chromosome 7 abnormalities. We investigated whether cytogenetically cryptic EVI1 rearrangements may cause EVI1 overexpression in myeloid malignancies without 3q26 abnormalities and investigated 983 patients with AML (n = 606) or myelodysplastic syndromes (MDS; n = 377) with normal karyotype (CN-AML/CN-MDS, n = 594) or chromosome 7 abnormalities (n = 389) for EVI1 rearrangements using interphase FISH. We identified cytogenetically cryptic EVI1 rearrangements in 27 patients (19 AML, 8 MDS): inv(3)(p24q26) [n = 10]; t(3;21)(q26;q11) [n = 9]; and der(7)t(3;7)(q26;q21) [n = 8]. Elevated EVI1 expression was detected in nearly all cases with cryptic EVI1 rearrangements: Median %EVI1/ABL1 was 92.8 (range: 29.8-146.1) in inv(3)(p24q26), 104.9 (41.4-176.3) in t(3;21)(q26;q11), and 101.8 (4.4-210.4) in der(7)t(3;7)(q26;q21). This was similar to median %EVI1/ABL1 of 73.9 (range: 7.3-585.6) in an independent cohort of inv(3)(q21q26)/t(3;3)(q21;q26) and 67.1 (2.3-410.7) in other 3q26/EVI1 rearrangements. Healthy controls showed median EVI1 expression of 0.5 (range: 0.0-5.8). Using SNP microarray and sequencing analyses, the breakpoints of der(7)t(3;7)(q26;q21) were assigned to CDK6 and centromeric of EVI1, and of t(3;21)(q26;q11) to be within EVI1 and NRIP1. Median overall survival in patients with cryptic EVI1 rearrangements was short, comparable to patients with inv(3)(q21q26)/t(3;3)(q21;q26) or other EVI1 rearrangements. Cryptic EVI1 rearrangements contribute to explain the clinical heterogeneity of CN-AML and are associated with elevated EVI1 expression and an unfavorable prognosis. Screening for cryptic EVI1 rearrangements by FISH may be particularly appropriate in CN-AML with elevated EVI1 expression or in AML/MDS patients with chromosome 7 abnormalities.

Comprehensive profile of cytogenetics in 2308 Chinese children and adults with de novo acute myeloid leukemia

Diagnostic cytogenetic and molecular analysis is recognized as the most valuable prognostic factor in acute myeloid leukemia (AML). Among 2516 consecutive Chinese patients with de novo AML, 2308 patients had successful cytogenetic results including 61 subclasses of cytogenetic abnormalities and 27 kinds of additional cytogenetic abnormalities. The incidence of t(15;17)(q22;q12) was highest (16.7% of 2308 patients), followed by t(8;21)(q22;q22) (15.1%), trisomy 8 (5.5%), loss of Y (4.5%), trisomy 21 (2.4%), inv(16)(p13q22) or t(16;16)(p13;q22) (2.1%), etc. In comparison to children, adults had higher incidence of normal karyotype (41.5% vs. 29.1%, P<0.001) and lower incidences of t(8;21)(q22;q22) (13.4% vs. 25.8%, P<0.001), t(9;11)(p22;q23) (0.2% vs. 1.2%, P=0.001) and other 11q23 rearrangements (1.0% vs. 3.4%, P<0.001). Among 349 AML patients with t(8;21)(q22;q22), 310 (35.5%) were found in 873 patients with M2. The t(15;17)(q22;q12) was exclusively observed in 386 (71.0%) of 544 patients with M3. In 48 AML patients with inv(16)(p13q22) or t(16;16)(p13;q22), 42 (15.2%) were detected in 276 patients with M4. Our study displayed the cytogenetic characteristics in a large series of Chinese patients with de novo AML. Our results revealed the similarities and differences of cytogenetic abnormalities existing between Chinese and western AML patients.

Diversity of the juxtamembrane and TKD1 mutations (exons 13-15) in the FLT3 gene with regards to mutant load, sequence, length, localization, and correlation with biological data

In acute myeloid leukemia (AML) mutations in the juxtamembrane and tyrosine kinase 1 domain (exons 13-15) of the FLT3 gene (FLT3-ITD/LM) are heterogeneous with respect to mutation load, size, and localization. We characterized length and structure of these mutations by fragment analysis and sequencing in 689 AML which were identified among 3,365 (20.5%) newly diagnosed AML (1,803 males, 1,562 females; 15.8-91.8 years). Mutations were heterogeneous in length (median: 63, range: 3-1,236 nucleotides; nt). Most frequent were sizes of 21 (8.4%) or 24 nt (6.0%). Ninety-one different insertion sites were observed (between nt 1,788 and 1,934, according to accession "FLT3 [Ensembl/Havana merge: ENSG00000122025]" with nt 1,856 (n = 41) and 1,863 (n = 35) being most frequent. In addition, 89 different insertion end points were observed between nt 1,790 and 1,994. FLT3-mutation/wild-type ratio was available in 615 patients (median, 0.80; range 0.03-181.73). 128 Patients (20.8%) had ratios <0.3, 334 (54.3%) had ratio ≥0.3 <1, 118 (19.2%) ≥1, and 35 (5.7%) showed complete loss of the FLT3-wild-type allele. Overall (OS) and event-free (EFS) survival were better for FLT3-negative than FLT3mut normal karyotype patients (P = 0.078 and P = 0.004, respectively) and patients with low level FLT3-mutations had significantly longer OS and EFS compared with high level mutations (FLT3-mutation/wild-type ratio ≥1) (P < 0.001 and P = 0.002, respectively). The length of the mutation had no prognostic impact. Mutations localized more 5' were associated with better outcome than more 3'mutations, but no strict association to certain functional domains was detected. In conclusion, FLT3-mutations are extremely heterogenous with mutation load being the most relevant parameter.

Multilineage dysplasia does not influence prognosis in CEBPA-mutated AML, supporting the WHO proposal to classify these patients as a unique entity

In 2008, the World Health Organization introduced CEBPA (encoding the CCAAT/enhancer binding protein)–mutated acute myeloid leukemia (AML) as a provisional entity. However, the classification of CEBPA-mutated AML with multilineage dysplasia (MLD; ≥ 50% dysplastic cells in 2-3 lineages) remains to be clarified. In the present study, we investigated 108 CEBPA-mutated AML patients for the impact of MLD, karyotype, and additional mutations. MLD+ patients differed from MLD− patients only by lower mean WBC counts, not by biologic characteristics, cytogenetic risk profiles, or additional mutations. Survival was better for female patients, patients < 60 years of age, for intermediate versus adverse karyotypes, and, in the case of FLT3-ITD negativity, biallelic versus monoallelic/homozygous CEBPA mutations. In contrast, 2-year overall survival and event-free survival did not differ significantly between MLD+ and MLD− patients. By univariable Cox regression analysis, sex, age, WBC count, and cytogenetic risk category were related to overall survival, but MLD was not. Therefore, because dysplasia is not relevant for this subtype, CEBPA-mutated AML patients should be characterized only according to mutation status, cytogenetic risk group, or additional mutations.

The FLT3ITD mRNA level has a high prognostic impact in NPM1 mutated, but not in NPM1 unmutated, AML with a normal karyotype

The impact of a FLT3-internal tandem duplication (FLT3ITD) on prognosis of patients with acute myeloid leukemia (AML) is dependent on the ratio of mutated to wild-type allele. In 648 normal karyotype (NK) AML patients, we found a significant independent effect of the quantitative FLT3ITD mRNA level—measured as (FLT3ITD/wtFLT3)/(FLT3ITD/wtFLT3 + 1)—on outcome. Moreover, this effect was clearly seen in 329 patients with a mutated NPM1 gene (NPM1+), but not in 319 patients without a NPM1 mutation (wtNPM1). In a multivariate Cox regression model, the quantitative FLT3ITD mRNA level showed an independent prognostic impact on overall survival (OS) and relapse-free survival (RFS) only in the NPM1+ subgroup (OS: hazard ratio, 5.9; [95% confidence interval [CI]: 3.1-11.2]; RFS: hazard ratio, 7.5 [95% CI: 3.4-16.5]). The FLT3ITD mRNA level contributes to relapse risk stratification and might help to guide postremission therapy in NPM1-mutated AML.

Efficacy of tosedostat, a novel, oral agent for elderly patients with relapsed or refractory acute myeloid leukemia: a review of the Phase II OPAL trial

Acute myeloid leukemia is most often diagnosed in patients older than 60 years of age. Overall, these patients have a poor prognosis, partly because they are typically unable to tolerate intensive chemotherapy regimens traditionally offered to younger individuals. Furthermore, responses attained in these older patients are not durable, with most experiencing relapse within 1-2 years. Therefore, new strategies are needed to improve the outcome of older patients with acute myeloid leukemia. Tosedostat is an orally available aminopeptidase inhibitor shown to have activity in leukemia. This commentary discusses the background and results of an ongoing Phase II evaluation of tosedostat in elderly patients with relapsed or refractory acute myeloid leukemia. The data available to date is analyzed and future perspectives regarding the development of this agent is discussed.

Older patients with normal karyotype acute myeloid leukemia have a higher rate of genomic changes compared to young patients as determined by SNP array analysis

Older patients with AML have a worse outcome compared to young patients. To study for potential contributors to their poor prognosis, we compared two NK-AML cohorts, young (< 60 years old) and old (≥ 60 years old), via high density SNP array analysis. Older patients had more genomic changes (1.83 ± 0.23 vs. 1.16 ± 0.2, p=0.037) and a trend for a higher number of copy number neutral loss of heterozygosity (0.5 ± 0.2 vs. 0.24 ± 0.08, p=0.088) compared to young patients. We speculate that complex genomic changes in NK-AML may be a sign of an increase in genomic instability and an indicator of a worse prognosis.

ETV6 rearrangements are recurrent in myeloid malignancies and are frequently associated with other genetic events

ETV6 (TEL) rearrangements are favorable in pediatric acute lymphoblastic leukemia but are less well characterized in myeloid malignancies. We investigated 9,550 patients with myeloid disorders for ETV6 rearrangements by chromosome banding analysis and interphase fluorescence in situ hybridization. ETV6 rearrangements were identified in 51 of 9,550 (0.5%) patients (range, 19.2-85.3 years). Frequencies were in detail: acute myeloid leukemia (AML): 40 of 3,798, 1.1%; myelodysplastic syndromes (MDS): 6 of 3,375, 0.2%; myeloproliferative neoplasms (MPNs): 5 of 1,720, 0.3%; MDS/MPN: 0 of 210; and chronic myelomonocytic leukemia: 0 of 447. Thirty-three different partner bands of ETV6 were identified, and most were recurrent: 3q26 (n = 10), 5q33 (n = 4), 17q11 (n = 3), 22q12 (n = 3), 5q31 (n = 2), and 2q31 (n = 2). Additional chromosomal abnormalities were identified in 29 of 51 (57%) ETV6 rearranged cases. In AML, ETV6 rearrangements were frequently associated with NPM1 (9/39, 23%) and RUNX1 mutations (6/31, 19%). The FAB M0 subtype was more frequent in ETV6 rearranged de novo AML than other AML (P < 0.001); expression of CD7 and CD34 by immunophenotyping was higher in ETV6 rearranged AML compared with other subgroups. Survival of 29 ETV6 rearranged de novo AML was compared with 818 AML from other cytogenetic subgroups. Median overall and event-free survival of ETV6 rearranged cases was similar to the intermediate-risk cohort (26.3 vs. 62.2 months and 14.0 vs. 15.4 months) defined according to Medical Research Council criteria. Our study confirms the variety of ETV6 rearrangements in AML, MDS, and MPNs often in association with other genetic events. Prognosis of ETV6 rearranged de novo AML seems to be intermediate, which should be independently confirmed.

ABCB1 genetic variation and P-glycoprotein expression/activity in a cohort of Brazilian acute myeloid leukemia patients

PURPOSE

Polymorphisms in the ABCB1 gene may influence P-glycoprotein (Pgp) expression and/or activity. Because the population in Brazil is markedly heterogeneous, we analyzed the relationship between ABCB1 polymorphisms and Pgp expression/activity in Brazilian acute myeloid leukemia (AML) patients.

METHODS

Acute myeloid leukemia samples from 109 patients were studied. ABCB1 gene variants rs1128503 (C1236T) and rs1045643 (C3435T) were analyzed by PCR-RFLP assay. Pgp expression and Pgp activity were analyzed by flow cytometry.

RESULTS

There was a similar distribution of Pgp expression and activity on polymorphisms C1236T, C1236C, and T1236T for exon 12, and C3435T, C3435C, and T3435T for exon 26. An exception was observed in the lowest ratio of mean fluorescence intensity (MFI) median for Pgp expression in the TT genotype for both studied exons, and its correspondence to a low MFI median for Pgp activity. Pgp expression did not show impact on the response to remission induction therapy, but the MFI median of Pgp expression in the remission failure group was higher than that of the complete remission (CR) group of patients (p = 0.04). Overall survival (OS) was significantly influenced by CR (p = 0.0001). Better 5-year OS and 5-year event-free survival rates (p = 0.04 and p = 0.007, respectively) were achieved in patients presenting the genetic variant CC in exon 12 followed by those presenting the variant CT in exon 26 (p = 0.001).

CONCLUSIONS

Polymorphisms in the ABCB1 gene and the levels of Pgp expression could be useful to identify prognostic in AML patients.

Prediction of post-remission survival in acute myeloid leukaemia: a post-hoc analysis of the AML96 trial

BACKGROUND

The optimum post-remission treatment (PRT) in acute myeloid leukaemia (AML) is still a matter of debate. Consolidation treatments include chemotherapy with high-dose cytarabine, or allogeneic or autologous haemopoietic stem cell transplantation (HSCT). In a post-hoc analysis of the AML96 trial (NCT00180115), our aim was to differentiate groups of patients according to the treatments that would provide them optimum benefit.

METHODS

In the multicentre AML96 trial, 586 patients (aged 15-60 years) with AML--excluding those with t(8;21)--who were in complete remission after double induction treatment were consolidated with allogeneic HSCT, autologous HSCT, or chemotherapy containing high-dose cytarabine in a priority-based and risk-adapted manner. We assessed the association between potentially prognostic variables and overall survival after complete remission by use of a stratified Cox regression analysis. With the significant variables of the resulting model, we developed a PRT score in 452 patients with a complete dataset. This score was then validated by use of data from 407 patients from the AML2003 trial (NCT00180102).

FINDINGS

Age, percentage of CD34-positive blasts, FLT3-ITD mutant-to-wild-type ratio, cytogenetic risk, and de-novo or secondary AML were identified as independent prognostic factors, and included in the PRT score. The PRT score separated patients in AML96 into three groups: favourable (n=190; 3-year survival 68%, 95% CI 60-74), intermediate (n=198; 49%, 42-56), and unfavourable (n=64; 20%, 12-31). All pair-wise comparisons of two of three PRT score groups were significant in the log-rank test (p<0·0001). Similar results were noted when data from AML2003 were used: 3-year survival for the favourable group (n=265) was 69% (62-76), for the intermediate group (n=114) it was 61% (50-71), and for the unfavourable group (n=28) it was 46% (24-65). The overall comparison between the three risk groups resulted in significantly different survival probabilities (p=0·015). We also analysed response to treatment in AML96 in each of the PRT score groups. In the favourable group, patients given allogeneic HSCT (n=60) had higher survival probabilities (82%, 69-89) than did those given chemotherapy (n=56, 55%, 41-67; p=0·0012) or autologous HSCT (n=74, 66%, 54-76; p=0·044). In the intermediate PRT score group, patients given autologous HSCT (n=69) had the best survival probabilities (62%, 50-72) compared with those given chemotherapy (n=72, 41%, 30-52; p=0·0006) or allogeneic HSCT (n=57, 44%, 31-56; p=0·0045).

INTERPRETATION

The PRT score groups could help physicians to tailor treatment for patients with AML and our results lend support to the use of autologous HSCT in patients aged 60 years or younger with an intermediate PRT score.

FUNDING

Deutsche Krebshilfe.

The treatment of elderly patients with acute myeloid leukemia

BACKGROUND

In patients over age 60 with acute myeloid leukemia (AML), cure rates are under 10% despite intensive chemotherapy. These patients often have comorbidities, and their treatment must be chosen with care. For those who are not candidates for intensive chemotherapy, one of the available options for palliative treatment should be chosen on the basis of an individual risk-benefit assessment.

METHODS

Selective literature review.

RESULTS

An evaluation of the patient's general condition and comorbidities, a geriatric assessment, and specially designed risk scores are useful aids to the choice of an appropriate treatment. Some elderly patients with AML can benefit from intensive chemotherapy despite their age; for highly selected elderly patients, allogeneic stem-cell transplantation is an increasingly feasible option. Hypomethylating agents or low-dose cytarabine can be suitable for some patients. Further options include experimental treatment as part of a clinical trial, and supportive care alone. In the special case of acute promyelocytic leukemia, more than half of all patients can be cured with combination chemotherapy including all-trans retinoic acid.

CONCLUSION

The prognosis of elderly AML patients remains poor despite recent therapeutic advances. The appropriate treatment for each patient can be chosen on the basis of a risk-benefit assessment. Clinical trials evaluating new treatments are urgently needed.

Similarities and differences between therapy-related and elderly acute myeloid leukemia

Acute myeloid leukemia (AML) is a clonal disorder of the hematopoietic stem cell, typical of the elderly, with a median age of over 60 years at diagnosis. In AML, older age is one of the strongest independent adverse prognostic factor, associated with decreased complete response rate, worse disease-free and overall survival, with highest rates of treatment related mortality, resistant disease and relapse, compared to younger patients. Outcomes are compromised in older patients not only by increased comorbidities and susceptibility to toxicity from therapy, but it is now recognized that elderly AML has peculiar biologic characteristics with a negative impact on treatment response.

In older individuals prolonged exposure to environmental carcinogens may be the basis for similarities to therapy-related myeloid malignancies (t-MN), which result from toxic effects of previous cytotoxic treatments on hematopoietic stem cells. Age is itself a risk factor for t-MN, which are more frequent in elderly patients, where also a shorter latency between treatment of primary tumor and t-MN has been reported. t-MN following chemotherapy with alkylating agents and elderly AML frequently present MDS-related cytogenetic abnormalities, including complex or monosomal karyotype, and a myelodysplastic phase preceding the diagnosis of overt leukemia. Similarly, t-MN and elderly-AML share common molecular abnormalities, such as reduced frequency of NPM1, FLT3 and CEBPA mutations and increased MDR1 expression.

Given the unfavorable prognosis of elderly and t-MN and the similar clinical and molecular aspects, this is a promising field for implementation of new treatment protocols including alternative biological drugs.

[Current treatment options in acute myeloid leukemia]

Genetic aberrations form the basis for diagnostic classification of patients with acute myeloid leukemia (AML) according to the World Health Organization (WHO) classification. Moreover, these aberrations predict response to induction chemotherapy, relapse-free survival, and overall survival of patients with AML. Understanding the pathogenetic role of cytogenetic and molecular changes has led to the development of targeted treatment strategies that require rapid diagnostic assessment of the genetic profile of each patient to select the best treatment available.

A multicenter phase II trial of decitabine as first-line treatment for older patients with acute myeloid leukemia judged unfit for induction chemotherapy

BACKGROUND

The treatment of acute myeloid leukemia of older, medically non-fit patients still poses a highly unmet clinical need, and only few large, prospective studies have been performed in this setting. Given the established activity of hypomethylating agents such as 5-aza-2'-deoxycytidine (decitabine) in myelodysplastic syndromes and acute myeloid leukemia with 20-30% bone marrow blasts, we investigated whether this drug is also active in patients with more than 30% blasts.

DESIGN AND METHODS

To evaluate the efficacy and toxicity of decitabine in patients over 60 years old with untreated acute myeloid leukemia ineligible for induction chemotherapy, 227 patients (median age, 72 years), many with comorbidities, adverse cytogenetics and/or preceding myelodysplastic syndrome were treated with this hypomethylating agent. During the initial decitabine treatment (135 mg/m(2) total dose infused intravenously over 72 hours every 6 weeks), a median of two cycles was administered (range, 1-4). All-trans retinoic acid was administered to 100 patients during course 2. Fifty-two patients who completed four cycles of treatment subsequently received a median of five maintenance courses (range, 1-19) with a lower dose of decitabine (20 mg/m(2)) infused over 1 hour on 3 consecutive days every 4-6 weeks.

RESULTS

The complete and partial remission rate was 26%, 95% CI (20%, 32%), and an antileukemic effect was noted in 26% of patients. Response rates did not differ between patients with or without adverse cytogenetics; patients with monosomal karyotypes also responded. The median overall survival from the start of decitabine treatment was 5.5 months (range, 0-57.5+) and the 1-year survival rate was 28%, 95%CI (22%,34%). Toxicities were predominantly hematologic.

CONCLUSIONS

Decitabine is well tolerated by older, medically non-fit patients with acute myeloid leukemia; myelosuppression is the major toxicity. The response rate and overall survival were not adversely influenced by poor-risk cytogenetics or myelodysplastic syndrome. Because of these encouraging results, randomized studies evaluating single-agent decitabine versus conventional treatment are warranted. The study is registered with the German Clinical Trials Registry, number DRKS00000069.

Outpatient consolidation treatment with clofarabine in a phase 2 study of older adult patients with previously untreated acute myelogenous leukemia

This report describes outpatient (OP) administration of clofarabine in older patients (≥60 years) with untreated acute myelogenous leukemia (AML). Overall, 112 patients underwent clofarabine induction. Clofarabine was administered to 35 OPs for a total of 72 OP cycles, with 81% of these cycles representing consolidation treatment. Median length of hospital stay was 0-6 days and 5-25 days across OP and inpatient (IP) cycles, respectively. The most common adverse events (AEs) were nausea, vomiting, diarrhea, febrile neutropenia, edema, hypokalemia and pneumonia. The overall frequency of treatment-emergent grade ≥3 AEs and serious AEs was generally not different with IP or OP administration of clofarabine. No deaths were reported within 30 days following OP or IP consolidation cycles. In the appropriately selected older patient, OP administration of clofarabine consolidation appears feasible, is as well tolerated as IP administration and has potential to contribute to the quality of life in elderly patients with AML.

Induction therapy of AML with ara-C plus daunorubicin versus ara-C plus gemtuzumab ozogamicin: a randomized phase II trial in elderly patients

BACKGROUND

Chemotherapy for elderly patients with acute myeloid leukemia (AML) results in a median overall survival (OS) of ≤ 1 year. Elderly patients often present with cardiac comorbidity. Gemtuzumab ozogamicin (GO) is active in elderly (≥ 60 years) patients with relapsed AML with low cardiac toxicity.

PATIENTS AND METHODS

This randomized phase II study compared a standard combination of ara-C and daunorubicin (DNR; 7+3) versus ara-C plus gemtuzumab ozogamicin (7+GO) as the first course of induction therapy. Primary objectives were comparison of blast clearance on day 16, event-free survival (EFS), and remission duration. OS, complete remission (CR), and tolerability were secondary objectives.

RESULTS

One hundred and nineteen patients with de novo AML, treatment-related AML, AML with a history of myelodysplastic syndrome (MDS), or high-risk MDS entered the study. Median age of 115 patients (intent-to-treat population) was 69 years. Protocol outlined a second course 7+3 for patients without blast clearance and two courses of high-dose ara-C consolidation upon CR. Both treatments were equally effective in blast clearance, CR, EFS, remission duration, or OS (median: 7+3, 9 months; 7+GO, 10 months). Induction death rate was higher in the GO group due to veno-occlusive disease.

CONCLUSION

The study did not show significant superiority of 7+GO over standard 7+3.

Long-Term Prognosis of Acute Myeloid Leukemia According to the New Genetic Risk Classification of the European LeukemiaNet Recommendations: Evaluation of the Proposed Reporting System

Purpose

The current European LeukemiaNet (ELN) recommendations for acute myeloid leukemia (AML) propose a new risk reporting system, integrating molecular and cytogenetic factors and subdividing the large heterogenous group of intermediate-risk patients into intermediate-I (IR-I) and intermediate-II (IR-II). We assessed the prognostic value of the new risk classification in a large cohort of patients.

Patients and Methods

Complete data for classification were available for 1,557 of 1,862 patients treated in the AML96 trial. Patients were assigned to the proposed genetic groups from the ELN recommendations, and survival analyses were performed using the Kaplan-Meier method and log-rank test for significance testing.

Results

The median age of all patients was 67 years. With a median follow-up of 8.3 years, significant differences between all risk categories were observed in patients age ≤ 60 years regarding the time to relapse, relapse-free survival, and overall survival (OS). Patients in the IR-II group had a better prognosis than patients in the IR-I group. The median OS times in young patients with favorable risk (FR), IR-I, IR-II, and adverse risk (AR) were 5.3, 1.1, 1.6, and 0.5 years, respectively. Separate analyses in the age group older than 60 years revealed significant differences between FR, AR, and IR as a whole, but not between IR-I and IR-II.

Conclusion

In younger patients with AML, the ELN classification seems to be the best available framework for prognostic estimations to date. Caution is advised concerning its use for prospective treatment allocation before it has been prospectively validated. In elderly patients, alternative prognostic factors are desirable for further risk stratification of IR.

Acute myeloid leukaemia in the elderly: a review

The majority of patients with acute myeloid leukaemia (AML) are elderly. Advancements in supportive care and regimen intensification have resulted in improvements in clinical outcomes for younger AML patients, but analogous improvements in older patients have not been realized. While outcomes are compromised by increased comorbidities and susceptibility to toxicity from therapy, it is now recognized that elderly AML represents a biologically distinct disease that is more aggressive and less responsive to therapy. Some patients tolerate and benefit from intensive remission-induction approaches, while others are best managed with less aggressive strategies. The challenge is to differentiate these groups based on host-related and biological features, in order to maximize the therapeutic benefit and minimize toxicity. As more is understood about the complicated pathogenesis and molecular basis of AML, there are more opportunities to develop and test targeted therapies. Elderly patients, with their narrow therapeutic window, are well positioned to derive a benefit from these novel agents, and therefore, despite a difficult past, there are reasons to be optimistic about the future of elderly AML.

AML1/ETO induces self-renewal in hematopoietic progenitor cells via the Groucho-related amino-terminal AES protein

The most frequent translocation t(8;21) in acute myeloid leukemia (AML) generates the chimeric AML1/ETO protein, which blocks differentiation and induces self-renewal in hematopoietic progenitor cells. The underlying mechanisms mediating AML1/ETO-induced self-renewal are largely unknown. Using expression microarray analysis, we identified the Groucho-related amino-terminal enhancer of split (AES) as a consistently up-regulated AML1/ETO target. Elevated levels of AES mRNA and protein were confirmed in AML1/ETO-expressing leukemia cells, as well as in other AML specimens. High expression of AES mRNA or protein was associated with improved survival of AML patients, even in the absence of t(8;21). On a functional level, knockdown of AES by RNAi in AML1/ETO-expressing cell lines inhibited colony formation. Similarly, self-renewal induced by AML1/ETO in primary murine progenitors was inhibited when AES was decreased or absent. High levels of AES expression enhanced formation of immature colonies, serial replating capacity of primary cells, and colony formation in colony-forming unit-spleen assays. These findings establish AES as a novel AML1/ETO-induced target gene that plays an important role in the self-renewal phenotype of t(8;21)-positive AML.

Allogeneic transplantation as post-remission therapy for cytogenetically high-risk acute myeloid leukemia: landmark analysis from a single prospective multicenter trial

Background Allogeneic hematopoietic cell transplantation is considered the preferred post-remission therapy in patients with acute myeloid leukemia cytogenetically defined as being at high risk. To substantiate evidence for allogeneic hematopoietic cell transplantation in first complete remission in these high-risk patients we performed a landmark analysis within a single prospective multicenter treatment trial.

DESIGN AND METHODS

By the time of analysis, 2,347 patients had been accrued into the AMLCG 99 trial between 1999 - 2007. Out of this population, 243 patients under 60 years old fulfilled the criteria for high-risk cytogenetics. Landmark analyses were performed with a control cohort, who remained in first complete remission at least the median time from complete remission to transplantation in the intervention group.

RESULTS

After standardized induction therapy, 111 patients under 60 years old achieved complete remission. A matched allogeneic donor was identified for 59 patients (30 sibling donors, 29 unrelated donors). Fifty-five patients received an allogeneic hematopoietic cell transplant after a median time of 88 days in first complete remission. Of the remaining 56 patients, 21 relapsed within 90 days after achieving first complete remission and for 7 patients with relevant comorbidities no donors search was initiated, leaving 28 patients given conventional post-remission therapy as the control cohort. The median follow-up of surviving patients was 60.4 months. Patients with an allogeneic donor had substantially better 5-year overall and relapse-free survival rates than the control group (48% versus 18%, P=0.004 and 39% versus 10%, P<0.001, respectively). A survival benefit from transplantation was evident regardless of donor type, age and monosomal karyotype. Conclusions Beyond evidence available for subgroups of high-risk patients, the findings of this study establish in a broader manner that allogeneic hematopoietic cell transplantation is a preferable consolidation treatment for patients with acute myeloid leukemia and high-risk cytogenetics. The study was registered at Clinicaltrials.gov as NCT00266136.

Malignant hematologic diseases in adolescents and young adults

Adolescents and young adults (AYA) with cancer have been designated as a vulnerable population by the National Cancer Institute. This group, defined by the ages of 16-39 years, has not enjoyed the same survival improvements over the past several decades as older and younger cohorts. Several barriers prevent the optimal delivery of oncologic care in this subpopulation. This review will describe these challenges in the context of the major hematologic malignancies affecting this population (acute lymphoblastic leukemia [ALL], acute myeloid leukemia [AML], Hodgkin lymphoma [HL], and non-Hodgkin lymphoma [NHL]). For example, historical differences in care delivery between pediatric and adult health care systems have created confusion about optimal treatment planning for AYAs, a population that spans the pediatric-adult divide. In the case of ALL, retrospective studies have demonstrated significantly better outcomes when AYAs are treated according to pediatric and not adult protocols. Additional challenges more specific to AYAs include increased treatment-related toxicity relative to younger patients; less access to care and, specifically, access to clinical trials; lower adherence to medications and treatment plans; and psychosocial stressors relevant to individuals at this stage of life. Recognizing and responding to these challenges in AYAs may create opportunities to improve the cancer outcomes of this group.

Early allo-SCT for AML with a complex aberrant karyotype--results from a prospective pilot study

In AML, a complex aberrant karyotype is associated with poor response to chemotherapy and dismal prognosis. We prospectively studied the concept of allogeneic haematopoietic SCT (HSCT), performed early and regardless of response to induction treatment in patients with complex karyotype AML (CK-AML). The preparative regimen consisted of fludarabine, Ara-C and amsacrine (FLAMSA) chemotherapy, followed by reduced intensity conditioning (RIC) 3 days later. In vivo T-cell depletion by anti-thymocyte globulin was used to protect from early GvHD, and prophylactic donor lymphocyte transfusion was given from day+120 to augment the GvL effect, once tolerance was established. Eighteen consecutive patients with CK-AML (median age: 53 years) received HSCT from related (n=7) or unrelated (n=11) donors. Before FLAMSA-RIC, nine patients each had received one and two induction courses. Stage at start of FLAMSA-RIC was CR/CRi (n=8) or persistent disease (n=10). Following HSCT, 16 patients achieved CR. After a follow-up of 51 months, 11 patients are alive in CR, whereas seven have died in remission (n=3), or from leukaemia (n=4). Cumulative incidence of relapse, non-relapse mortality, acute GvHD≥II and chronic GvHD were 0.222±0.098, 0.235±0.104, 0.367±0.120 and 0.481±0.123, respectively. Four-year survival from HSCT is 61%. Early HSCT following FLAMSA-RIC may improve the outcome of this unfavourable AML subgroup.

Therapeutic advances in acute myeloid leukemia

The choice of treatment approach and outcome in acute myeloid leukemia (AML) depends on the age of the patient. In younger patients, arbitrarily defined as being younger than 60 years, 70% to 80% enter complete disease remission with several anthracycline-based chemotherapy combinations. Consolidation with high-dose cytarabine or stem-cell transplantation in high-risk patients will restrict overall relapse to approximately 50%. A number of demographic features can predict the outcome of treatment including cytogenetics and an increasing list of molecular features (ie, FLT3, NPM1, MLL, WT1, CEBPalpha, EVI1). These are increasingly being used to direct postinduction therapy, but they are also molecular targets for a new generation of small molecule inhibitors that are in early development; however, randomized data have yet to emerge. In older patients who comprise the majority, which will increase with demographic change, the initial clinical decision to be made is whether the patient should receive an intensive or nonintensive approach. If the same anthracycline/cytarabine-based approach is deployed, the remission rate will be around 50%, but the risk of subsequent relapse is approximately 85% at 3 years. This difference from younger patients is explained partly by the ability of patients to tolerate effective therapy, and also the aggregation of several poor risk factors compared with the young. There remains a substantial proportion of patients older than 60 years who do not receive intensive chemotherapy. Their survival is approximately 4 months, but there is considerable interest in developing new treatments for this patient group, including novel nucleoside analogs and several other agents.

Molecular genetics of adult acute myeloid leukemia: prognostic and therapeutic implications

Molecular analyses of leukemic blasts from patients with acute myeloid leukemia (AML) have revealed a striking heterogeneity with regard to the presence of acquired gene mutations and changes in gene and microRNA expression. Multiple submicroscopic genetic alterations with prognostic significance have been discovered. Application of gene- and microRNA profiling has identified genome-wide expression signatures that separate cytogenetic and molecular subsets of patients with AML into previously unrecognized biologic and/or prognostic subgroups. These and similar future findings are likely to have a major impact on the clinical management of AML because many of the identified genetic alterations not only represent independent prognosticators, but also may constitute targets for specific therapeutic intervention. In this report, we review genetic findings in AML and discuss their clinical implications.

Novel approaches to the treatment of acute myeloid leukemia

Approximately 12 000 adults are diagnosed with acute myeloid leukemia (AML) in the United States annually, the majority of whom die from their disease. The mainstay of initial treatment, cytosine arabinoside (ara-C) combined with an anthracycline, was developed nearly 40 years ago and remains the worldwide standard of care. Advances in genomics technologies have identified AML as a genetically heterogeneous disease, and many patients can now be categorized into clinicopathologic subgroups on the basis of their underlying molecular genetic defects. It is hoped that enhanced specificity of diagnostic classification will result in more effective application of targeted agents and the ability to create individualized treatment strategies. This review describes the current treatment standards for induction, consolidation, and stem cell transplantation; special considerations in the management of older AML patients; novel agents; emerging data on the detection and management of minimal residual disease (MRD); and strategies to improve the design and implementation of AML clinical trials.

Identification of patients with acute myeloblastic leukemia who benefit from the addition of gemtuzumab ozogamicin: results of the MRC AML15 trial

PURPOSE

Antibody-directed chemotherapy for acute myeloid leukemia (AML) may permit more treatment to be administered without escalating toxicity. Gemtuzumab ozogamicin (GO) is an immunoconjugate between CD33 and calicheamicin that is internalized when binding to the epitope. We previously established that it is feasible to combine GO with conventional chemotherapy. We now report a large randomized trial testing the addition of GO to induction and/or consolidation chemotherapy in untreated younger patients.

PATIENTS AND METHODS

In this open-label trial, 1,113 patients, predominantly younger than age 60 years, were randomly assigned to receive a single dose of GO (3 mg/m(2)) on day 1 of induction course 1 with one of the following three induction schedules: daunorubicin and cytarabine; cytarabine, daunorubicin, and etoposide; or fludarabine, cytarabine, granulocyte colony-stimulating factor, and idarubicin. In remission, 948 patients were randomly assigned to GO in course 3 in combination with amsacrine, cytarabine, and etoposide or high-dose cytarabine. The primary end points were response rate and survival.

RESULTS

The addition of GO was well tolerated with no significant increase in toxicity. There was no overall difference in response or survival in either induction of consolidation. However, a predefined analysis by cytogenetics showed highly significant interaction with induction GO (P = .001), with significant survival benefit for patients with favorable cytogenetics, no benefit for patients with poor-risk disease, and a trend for benefit in intermediate-risk patients. An internally validated prognostic index identified approximately 70% of patients with a predicted benefit of 10% in 5-year survival.

CONCLUSION

A substantial proportion of younger patients with AML have improved survival with the addition of GO to induction chemotherapy with little additional toxicity.

Complete remission and early death after intensive chemotherapy in patients aged 60 years or older with acute myeloid leukaemia: a web-based application for prediction of outcomes

BACKGROUND

About 50% of patients (age ≥60 years) who have acute myeloid leukaemia and are otherwise medically healthy (ie, able to undergo intensive chemotherapy) achieve a complete remission (CR) after intensive chemotherapy, but with a substantially increased risk of early death (ED) compared with younger patients. We verified the association of standard clinical and laboratory variables with CR and ED and developed a web-based application for risk assessment of intensive chemotherapy in these patients.

METHODS

Multivariate regression analysis was used to develop risk scores with or without knowledge of the cytogenetic and molecular risk profiles for a cohort of 1406 patients (aged ≥60 years) with acute myeloid leukaemia, but otherwise medically healthy, who were treated with two courses of intensive induction chemotherapy (tioguanine, standard-dose cytarabine, and daunorubicin followed by high-dose cytarabine and mitoxantrone; or with high-dose cytarabine and mitoxantrone in the first and second induction courses) in the German Acute Myeloid Leukaemia Cooperative Group 1999 study. Risk prediction was validated in an independent cohort of 801 patients (aged >60 years) with acute myeloid leukaemia who were given two courses of cytarabine and daunorubicin in the Acute Myeloid Leukaemia 1996 study.

FINDINGS

Body temperature, age, de-novo leukaemia versus leukaemia secondary to cytotoxic treatment or an antecedent haematological disease, haemoglobin, platelet count, fibrinogen, and serum concentration of lactate dehydrogenase were significantly associated with CR or ED. The probability of CR with knowledge of cytogenetic and molecular risk (score 1) was from 12% to 91%, and without knowledge (score 2) from 21% to 80%. The predicted risk of ED was from 6% to 69% for score 1 and from 7% to 63% for score 2. The predictive power of the risk scores was confirmed in the independent patient cohort (CR score 1, from 10% to 91%; CR score 2, from 16% to 80%; ED score 1, from 6% to 69%; and ED score 2, from 7% to 61%).

INTERPRETATION

The scores for acute myeloid leukaemia can be used to predict the probability of CR and the risk of ED in older patients with acute myeloid leukaemia, but otherwise medically healthy, for whom intensive induction chemotherapy is planned. This information can help physicians with difficult decisions for treatment of these patients.

FUNDING

Deutsche Krebshilfe and Deutsche Forschungsgemeinschaft.

The European LeukemiaNet: achievements and perspectives

The only way to cure leukemia is by cooperative research. To optimize research, the European LeukemiaNet integrates 105 national leukemia trial groups and networks, 105 interdisciplinary partner groups and about 1,000 leukemia specialists from 175 institutions. They care for tens of thousands of leukemia patients in 33 countries across Europe. Their ultimate goal is to cure leukemia. Since its inception in 2002, the European LeukemiaNet has steadily expanded and has unified leukemia research across Europe. The European LeukemiaNet grew from two major roots: 1) the German Competence Network on Acute and Chronic Leukemias; and 2) the collaboration of European Investigators on Chronic Myeloid Leukemia. The European LeukemiaNet has improved leukemia research and management across Europe. Its concept has led to funding by the European Commission as a network of excellence. Other sources (European Science Foundation; European LeukemiaNet-Foundation) will take over when the support of the European Commission ends.

Has there been progress in the treatment of older patients with acute myeloid leukemia?

The treatment of older patients with acute myeloid leukemia (AML) has become increasingly important as the population ages. Progress, measured by overall survival rates, has improved in younger patients, perhaps due to the use of intensive post-remission therapies, but it is unclear what will enable progress for older AML patients. The older AML patient population is very heterogeneous, and both patient-specific and leukemia-specific factors must be taken into consideration when choosing the therapy that will most benefit each patient. In addition to standard and intensive chemotherapy regimens, a number of alternative therapies for previously untreated older AML patients are currently being investigated. These include gemtuzumab ozogamicin, azacitidine, decitabine, and clofarabine.

Acute myeloid leukemia with mutated nucleophosmin (NPM1): is it a distinct entity?

After the discovery of NPM1-mutated acute myeloid leukemia (AML) in 2005 and its subsequent inclusion as a provisional entity in the 2008 World Health Organization classification of myeloid neoplasms, several controversial issues remained to be clarified. It was unclear whether the NPM1 mutation was a primary genetic lesion and whether additional chromosomal aberrations and multilineage dysplasia had any impact on the biologic and prognostic features of NPM1-mutated AML. Moreover, it was uncertain how to classify AML patients who were double-mutated for NPM1 and CEBPA. Recent studies have shown that: (1) the NPM1 mutant perturbs hemopoiesis in experimental models; (2) leukemic stem cells from NPM1-mutated AML patients carry the mutation; and (3) the NPM1 mutation is usually mutually exclusive of biallelic CEPBA mutations. Moreover, the biologic and clinical features of NPM1-mutated AML do not seem to be significantly influenced by concomitant chromosomal aberrations or multilineage dysplasia. Altogether, these pieces of evidence point to NPM1-mutated AML as a founder genetic event that defines a distinct leukemia entity accounting for approximately one-third of all AML.

Treatment of therapy-related myeloid neoplasms with high-dose cytarabine/mitoxantrone followed by hematopoietic stem cell transplant

Few clinical protocols have focused on patients with therapy-related myeloid neoplasms (t-MN). Therefore, we enrolled 32 patients with previously untreated t-MN on a clinical trial testing the effectiveness of a unified induction regimen of high-dose cytarabine and mitoxantrone. The complete remission (CR) rate was 66% (95% CI 47-81%) and the partial remission (PR) rate was 16% (95% CI 5-33%), for an overall response rate of 82%. Day 30 treatment mortality was 9% (3/32), and the most serious induction toxicity was cardiac dysfunction. Among the patients with CR, 13 (62%) received consolidation therapy using an allogeneic hematopoietic cell transplant (HCT), four (21%) received an autologous HCT, and three (16%) received further chemotherapy. We observed long-term disease-free survival in patients who received all three types of consolidation therapy. The remission induction of high-dose cytarabine and mitoxantrone for t-MN is a well-tolerated efficacious combination, which allows aggressive consolidation and long-term disease-free survival.

IDH1 mutations are detected in 6.6% of 1414 AML patients and are associated with intermediate risk karyotype and unfavorable prognosis in adults younger than 60 years and unmutated NPM1 status

Mutations in the IDH1 gene at position R132 coding for the enzyme cytosolic isocitrate dehydrogenase are known in glioma and have recently been detected also in acute myeloid leukemia (AML). These mutations result in an accumulation of α-ketoglutarate to R (2)-2-hydroxyglutarate (2HG). To further clarify the role of this mutation in AML, we have analyzed IDH1R132 in 1414 AML patients. We detected IDH1R132 mutations in 93 of 1414 patients (6.6%) with a clear prevalence in intermediate risk karyotype group (10.4%, P < .001). Although IDH1R132 mutations can incidentally occur together with all other molecular markers, there were strong associations with NPM1 mutations (14.2% vs 5.4% in NPM1wt, P < .001) and MLL-PTD (18.2% vs 7.0% in MLLwt, P = .020). IDH1-mutated cases more often had AML without maturation/French-American-British M1 (P < .001), an immature immunophenotype, and female sex (8.7% vs 4.7% in male, P = .003) compared with IDH1wt cases. Prognosis was adversely affected by IDH1 mutations with trend for shorter overall survival (P = .110), a shorter event-free survival (P < .003) and a higher cumulative risk for relapse (P = .001). IDH1 mutations were of independent prognostic relevance for event-free survival (P = .039) especially in the age group < 60 years (P = .028). In conclusion, these data show that IDH1R132 may significantly add information regarding characterization and prognostication in AML.

A novel prognostic model in elderly patients with acute myeloid leukemia: results of 909 patients entered into the prospective AML96 trial

We present an analysis of prognostic factors derived from a trial in patients with acute myeloid leukemia older than 60 years. The AML96 trial included 909 patients with a median age of 67 years (range, 61-87 years). Treatment included cytarabine-based induction therapy followed by 1 consolidation. The median follow-up time for all patients is 68 months (5.7 years). A total of 454 of all 909 patients reached a complete remission (50%). Five-year overall survival (OS) and disease-free survival were 9.7% and 14%, respectively. Multivariate analyses revealed that karyotype, age, NPM1 mutation status, white blood cell count, lactate dehydrogenase, and CD34 expression were of independent prognostic significance for OS. On the basis of the multivariate Cox model, an additive risk score was developed that allowed the subdivision of the largest group of patients with an intermediate-risk karyotype into 2 groups. We are, therefore, able to distinguish 4 prognostic groups: favorable risk, good intermediate risk, adverse intermediate risk, and high risk. The corresponding 3-year OS rates were 39.5%, 30%, 10.6%, and 3.3%, respectively. The risk model allows further stratification of patients with intermediate-risk karyotype into 2 prognostic groups with implications for the therapeutic strategy. This study was registered at www.clinicaltrials.gov as #NCT00180115.

How I treat acute myeloid leukemia

More than one quarter of a million adults throughout the world are diagnosed annually with acute myeloid leukemia (AML). Despite considerable progress during the past 3 decades in the therapy of AML, two-thirds of young adults and 90% of older adults still die of their disease. The reported median age has increased over the past few decades, mostly because of a greater willingness of physicians to diagnose and treat older patients, and now is 72 years. The greatest challenge is in this age group. However, much improvement in therapy is needed for all adults with AML. Recent advances in allogeneic transplantation, a better understanding of prognostic factors, and development of targeted agents have only modestly improved overall outcome when large populations of patients are considered. Although an explosion in knowledge about the molecular pathogenesis of AML has outpaced treatment advances, such insights hold promise for the development of new therapies directed at specific molecular abnormalities that perturb malignant cell survival pathways. The current approach in 2010 to the management of this disease is presented through a discussion of illustrative cases.

Prognostic factors in allo-SCT of elderly patients with AML

The prognosis of elderly patients with AML after chemotherapy is poor. Allo-SCT is feasible in these patients, but data on prognostic factors and outcome are limited. We analyzed all 102 AML patients ≥55 years, who underwent allo-SCT at our institution from 1997 to 2008. OS and relapse-free survival (RFS) rates at 3 years are 39 and 37%, respectively. Multivariate analysis for OS revealed age ≥60 years and active (refractory or untreated before allo-SCT) or advanced (>CR1) disease as adverse prognostic factors. Patients transplanted in CR1 had a 3-year OS of 67 vs 27% for patients with active/advanced disease. Multivariate analysis for RFS revealed active/advanced disease as the only adverse factor. Patients transplanted in CR1 had a 3-year RFS of 70 vs 22% for patients with active/advanced disease. In all, 17% of patients suffered from acute GVHD ≥grade II. The risk for severe acute GVHD was increased after allo-SCT from mismatched donors. Nonrelapse mortality (NRM) was 23% at 1 year. The only risk factor for NRM was active/advanced disease. In conclusion, allo-SCT from related or unrelated donors yields very good results in elderly AML patients transplanted in CR1. Disease status at transplantation is the most important prognostic factor for transplantation success.

Challenges in treating older patients with acute myeloid leukemia

Whereas in younger patients diagnosed with acute myeloid leukemia (AML) treatment is straightforward and the goal is cure, the optimal treatment decision for older adults remains highly controversial. Physicians need to determine whether palliation, “something” beyond palliation, intensive therapy, or an investigational therapy is the most appropriate treatment option. This requires understanding of the biology and risk profile of the AML, clinical judgment in evaluating the functional status of the patient, communication skills in understanding the patient's wishes and social background, and medical expertise in available therapies. The physician has to accurately inform the patient about (a) the unique biological considerations of his leukemia and his prognosis; (b) the risks and benefits of all available treatment options; (c) novel therapeutic approaches and how the patient can get access to these treatments. Last but not least, he has to recommend a treatment. This paper tries to discuss each of these issues.

Maintenance therapy in acute myeloid leukemia revisited: will new agents rekindle an old interest?

PURPOSE OF REVIEW

The potential and limitations of the established cytotoxic chemotherapy for acute myeloid leukemia have been assessed by recent large-scale clinical trials. A further progress would require the contribution of alternative approaches.

RECENT FINDINGS

Early results from more specific, less toxic, targeted agents are now available. Major options under investigation are demethylating drugs and inhibitors of tyrosine kinases, farnesylation and angiogenesis.

CONCLUSION

Some of the novel agents, such as demethylating drugs, appear predestined for prolonged maintenance treatment due to their delayed antileukemic mechanism.

Gemtuzumab ozogamicin as postremission treatment in AML at 60 years of age or more: results of a multicenter phase 3 study

In older patients with acute myeloid leukemia (AML), the prevention of relapse has remained one of the major therapeutic challenges, with more than 75% relapses after complete remission. The anti-CD33 immunotoxin conjugate gemtuzumab ozogamicin (GO) has shown antileukemic remission induction activity in patients with relapsed AML. Patients with AML or refractory anemia with excess blasts in first complete remission attained after intensive induction chemotherapy were randomized between 3 cycles of GO (6 mg/m2 every 4 weeks) or no postremission therapy (control) to assess whether GO would improve outcome. The 2 treatment groups (113 patients receiving GO vs 119 control patients) were comparable with regard to age (60-78 years, median 67 years), performance status, and cytogenetics. A total of 110 of 113 received at least 1 cycle of GO, and 65 of 113 patients completed the 3 cycles. Premature discontinuation was mainly attributable to incomplete hematologic recovery or intercurrent relapse. Median time to recovery of platelets 50 × 109/L and neutrophils 0.5 × 109/L after GO was 14 days and 20 days. Nonhematologic toxicities were mild overall, but there was 1 toxic death caused by liver failure. There were no significant differences between both treatment groups with regard to relapse probabilities, nonrelapse mortality, overall survival, or disease-free survival (17% vs 16% at 5 years). Postremission treatment with GO in older AML patients does not provide benefits regarding any clinical end points. The HOVON-43 study is registered at The Netherlands Trial Registry (number NTR212) and at http://www.controlled-trials.com as ISRCTN77039377.