Post-remission treatment of acute myelogenous leukemia

Induction of complete and molecular remissions in acute myeloid leukemia by Wilms' tumor 1 antigen-targeted dendritic cell vaccination

Active immunization using tumor antigen-loaded dendritic cells holds promise for the adjuvant treatment of cancer to eradicate or control residual disease, but so far, most dendritic cell trials have been performed in end-stage cancer patients with high tumor loads. Here, in a phase I/II trial, we investigated the effect of autologous dendritic cell vaccination in 10 patients with acute myeloid leukemia (AML). The Wilms' tumor 1 protein (WT1), a nearly universal tumor antigen, was chosen as an immunotherapeutic target because of its established role in leukemogenesis and superior immunogenic characteristics. Two patients in partial remission after chemotherapy were brought into complete remission after intradermal administration of full-length WT1 mRNA-electroporated dendritic cells. In these two patients and three other patients who were in complete remission, the AML-associated tumor marker returned to normal after dendritic cell vaccination, compatible with the induction of molecular remission. Clinical responses were correlated with vaccine-associated increases in WT1-specific CD8+ T cell frequencies, as detected by peptide/HLA-A*0201 tetramer staining, and elevated levels of activated natural killer cells postvaccination. Furthermore, vaccinated patients showed increased levels of WT1-specific IFN-gamma-producing CD8+ T cells and features of general immune activation. These data support the further development of vaccination with WT1 mRNA-loaded dendritic cells as a postremission treatment to prevent full relapse in AML patients.

Results of a HOVON/SAKK donor versus no-donor analysis of myeloablative HLA-identical sibling stem cell transplantation in first remission acute myeloid leukemia in young and middle-aged adults: benefits for whom?

The Dutch-Belgian Hemato-Oncology Cooperative Group and the Swiss Group for Clinical Cancer Research (HOVON-SAKK) collaborative study group evaluated outcome of patients (pts) with acute myeloid leukemia (AML) in first remission (CR1) entered in 3 consecutive studies according to a donor versus no-donor comparison. Between 1987 and 2004, 2287 pts were entered in these studies of whom 1032 pts (45%) without FAB M3 or t(15;17) were in CR1 after 2 cycles of chemotherapy, received consolidation treatment, and were younger than 55 years of age and therefore eligible for allogeneic hematopoietic stem cell transplantation (allo-SCT). An HLA-identical sibling donor was available for 326 pts (32%), whereas 599 pts (58%) lacked such a donor, and information was not available in 107 pts. Compliance with allo-SCT was 82% (268 of 326). Cumulative incidences of relapse were, respectively, 32% versus 59% for pts with versus those without a donor (P < .001). Despite more treatment-related mortality (TRM) in the donor group (21% versus 4%, P < .001), disease-free survival (DFS) appeared significantly better in the donor group (48% +/- 3% versus 37% +/- 2% in the no-donor group, P < .001). Following risk-group analysis, DFS was significantly better for pts with a donor and an intermediate- (P = .01) or poor-risk profile (P = .003) and also better in pts younger than 40 years of age (P < .001). We evaluated our results and those of the previous MRC, BGMT, and EORTC studies in a meta-analysis, which revealed a significant benefit of 12% in overall survival (OS) by donor availability for all patients with AML in CR1 without a favorable cytogenetic profile.

Consolidation therapy with autologous bone marrow transplantation in adults with acute myeloid leukemia: a meta-analysis

BACKGROUND

The optimal consolidation therapy for adults who are in first remission of acute myeloid leukemia after induction chemotherapy and who do not have a histocompatible donor is poorly established. We conducted a meta-analysis to compare the efficacy of autologous bone marrow transplantation with that of non-myeloablative chemotherapy alone (or no further treatment).

METHODS

Eligible studies were identified by searching electronic databases and by examining the reference lists of relevant studies and review articles. Eligible studies were those that prospectively enrolled adults with acute myeloid leukemia and randomly assigned patients who were in first remission and who did not have a matched sibling donor to one of the two consolidation therapies. Two reviewers independently assessed all studies for relevance and validity. We used a fixed-effects model to calculate the ratio of probabilities for disease-free and overall survival at 48 months or at the nearest recorded assessment point for each study and for all studies combined. All statistical tests were two-sided.

RESULTS

We identified 587 potentially relevant studies, 36 of which were retrieved for detailed evaluation. In the six studies eligible for this meta-analysis, a total of 1044 patients were randomly assigned to receive autologous bone marrow transplantation or non-myeloablative chemotherapy (five studies) or autologous bone marrow transplantation or no further treatment (one study). Compared with patients who received chemotherapy or no further treatment, patients who received autologous bone marrow transplantation had a better disease-free survival (ratio of disease-free survival probabilities = 1.24, 95% confidence interval [CI] = 1.06 to 1.44; P =.006) but a similar overall survival (ratio of overall survival probabilities = 1.01, 95% CI = 0.89 to 1.15; P =.86).

CONCLUSION

Our results do not support the routine use of autologous bone marrow transplantation in adult acute myeloid leukemia patients in first remission.

Leukemic dendritic cells: potential for therapy and insights towards immune escape by leukemic blasts

Dendritic cells (DCs) are a system of potent antigen-presenting cells (APCs) specialized to initiate primary immune responses. DCs are considered important elements in the induction of specific antitumor cytotoxic effectors. At present, because of potential therapeutic implications, the critical role of DCs in cancer patients is under intensive investigation. Interactions between DCs and acute myeloid leukemia cells represent an attractive model for the study of DC physiology. Moreover, DCs can be a valuable therapeutic tool for the adjuvant treatment of leukemic patients. However, DC subsets in vivo may also be affected by leukemogenesis and may contribute to the escape of leukemia from immune control. The aim of this review is to shed further light on this paradoxical picture where the line between immune tolerance and immune defense is narrow.

Assessment of minimal residual disease (MRD) in CBFbeta/MYH11-positive acute myeloid leukemias by qualitative and quantitative RT-PCR amplification of fusion transcripts

The inv(16)(p13q22) chromosomal rearrangement associated with FAB M4Eo acute myeloid leukemia (AML) subtype is characterized by the presence of the CBFbeta/MYH11 fusion transcript that can be used to detect minimal residual disease (MRD). However, qualitative RT-PCR studies of MRD have so far produced conflicting results and seem of limited prognostic value. We have evaluated retrospectively MRD in a large series of CBFbeta/MYH11-positive patients employing both qualitative and quantitative (real-time PCR) approaches. 186 bone marrow samples from 36 patients were examined with a median follow-up of 27.5 months; 15 patients relapsed during follow-up. In qualitative studies, carried out by 'nested' RT-PCR assay, all patients in complete remission (CR) immediately after induction/consolidation therapy were found to be PCR positive. However, follow-up samples at later time points were persistently negative (except one case) in patients remaining in continuous CR (CCR) for more than 12 months. 16 patients were evaluated by quantitative real-time PCR assay: CBFbeta/MYH11 transcript copy number was normalized for expression of the housekeeping gene ABL, expressed as fusion gene copy number per 10(4) copies of ABL. A 2-3 log decline in leukemic transcript copy number was observed after induction/consolidation therapy. After achieving CR, the mean copy number was significantly higher in patients destined to relapse compared to patients remaining in CCR (151 vs 9, P < 0.0001 by Mann-Whitney test). Moreover, in CCR patients, the copy number dropped below the detection threshold after the treatment protocol was completed and remained undetectable in subsequent MRD analysis in accordance with results obtained by qualitative RT-PCR. On the contrary, in the seven patients who relapsed, the copy number in CR never declined below the detection threshold; thus a cut-off value discriminating these two groups of patients could be established. The findings of our study, if confirmed, might confer an important predictive value to quantitative real-time PCR determinations of MRD in patients with inv(16) leukemia.

Intensive postremission chemotherapy in Taiwanese adults with acute myelogenous leukemia

Intensive postremission chemotherapy has produced disease-free survival comparable to that of bone marrow transplantation in patients with acute myelogenous leukemia (AML), but its efficacy was unknown in Taiwan. We assessed the efficacy of intensive postremission chemotherapy, consisting of high-dose arabinoside-C (HiDAC) with or without transplantation of peripheral blood stem cells, in 33 AML patients from a single institute in Taiwan. Toxic reactions, treatment outcome, prognostic factors, and the size of the peripheral blood stem-cell harvest after HiDAC were analyzed. After a median follow-up of 21 months, 18 patients remained in continuous complete remission. The actuarial leukemia-free survival at 4 years was 51%. Relapse occurred in 12 patients, at a median of 12 months after initial diagnosis. All 6 patients with acute promyelocytic leukemia remained disease free after HiDAC therapy. Age, sex, and number of remission-induction or intensive consolidation chemotherapy courses had no effect on the risk of relapse. Intensive postremission chemotherapy can effectively prolong the duration of remission in young (< 60 years of age) adults with AML.

Costs of diagnosis, treatment, and follow up of patients with acute myeloid leukemia in the netherlands

The aim of the study was to calculate the costs in various places of acute myeloid leukemia (AML). Patients less than 65 years old, who were treated for newly diagnosed AML were included. The cost analysis distinguished between diagnosis, treatment, follow-up (maximum of 2 years), and treatment of relapse. The treatment period was divided into remission induction and consolidation treatment, harvest of bone marrow (BM) or peripheral blood stem cells, and transplantation. The costs of diagnosis amounted to $3,167 (1995 US$). Remission-induction treatments cost on average $46,387 and harvest of bone marrow or peripheral blood stem cells costs $6,491. The costs of the transplantation varied between $25,531 and $44,087. Costs of follow-up amounted to $4,167. Relapse treatment, mainly consisting of reinduction therapy, costs on average $24,338. The total average weighted costs of AML patients amounted to $104,386. Treating AML patients is very expensive, and major reductions in costs are not expected in the next future. Considering efficacy and effectiveness, it seemed that choices based on costs could be made between several consolidation techniques and between a specific consolidation technique and/or palliative treatment.

Effect of centre on outcome of bone-marrow transplantation for acute myeloid leukaemia. Acute Leukaemia Working Party of the European Group for Blood and Marrow Transplantation

BACKGROUND

There is increasing pressure for the recognition and replication of good clinical practice. We undertook a study to assess the variability in outcome of allogeneic bone-marrow transplantation among major European centres.

METHODS

We studied 13 centres, including 522 patients (aged 16-55 years), which had undertaken more than 30 bone-marrow transplantations between Jan 1, 1987, and Dec 31, 1995, for acute myeloid leukaemia in first complete remission. We undertook a (global) multivariate analysis of all factors known previously to influence outcome and a stratified analysis that initially defined, by multivariate analysis, significant variables in this study and then used a proportional-hazard model including centres.

FINDINGS

The overall results at 3 years were 57% (95% CI 53-61) for leukaemia-free survival (LFS), 23% (19-27) for relapse incidence (RI), and 26% (22-30) for treatment-related mortality (TRM) with a range for centres of 36-75%, 10-37%, and 8-54%, respectively. Both methods of analysis showed the centre effect to be highly significant for LFS and TRM, but not for RI. Variables associated with a significantly poor outcome were age over 43 years (p=0.01), time from diagnosis to first complete remission longer than 65 days (p=0.02), and centre (p=0.013) for LFS, and age over 43 years (p=0.023), time from first complete remission to transplantation of longer than 93 days (p=0.03), and centre (p=0.001) for TRM. Moreover, different centres had different prognostic criteria for good-risk or bad-risk patients indicating that risk factors do not have the same impact in each individual centre.

INTERPRETATION

The outcome of bone-marrow transplantation for acute myeloid leukaemia in first complete remission is influenced by the centre in which the procedure is done, even with adjustment for known prognostic risk factors. Significant prognostic factors vary among centres, which means that the relative risk is not the same in each individual centre. However, centres may treat populations with different risks of as yet unidentified prognostic factors. Experience may partly account for the difference in outcome among centres.

Delphi-panel analysis of appropriateness of high-dose therapy and bone marrow transplants in adults with acute myelogenous leukemia in 1st remission

BACKGROUND

Despite considerable data, there is still controversy over which adults with acute myelogenous leukemia (AML) in 1st remission should receive high-dose therapy and a bone marrow transplant rather than conventional-dose chemotherapy. Analyses of data from randomized trials are complex, conclusions sometimes contradictory and results not sufficiently detailed to allow subject-level decisions.

OBJECTIVE

To determine appropriate use of high-dose therapy and bone marrow transplants in persons with AML in 1st remission with specific features. Develop a treatment algorithm. PANELISTS: Nine leukemia experts from diverse geographic sites and practice settings.

EVIDENCE

Boolean MEDLINE searches of acute myelogenous leukemia and chemotherapy and/or transplants.

CONSENSUS PROCESS

We used a modified Delphi-panel group judgment process. Age, WBC, cytogenetics and FAB-type were permuted to define 72 clinical settings. Each panelist rated appropriateness of high-dose therapy and a transplant versus conventional-dose chemotherapy on a nine-point ordinal scale (1, most inappropriate, 9, most appropriate) considering 3 types of donors: (1) HLA-identical siblings; (2) alternative donors (HLA-matched related or unrelated people other than an HLA-identical sibling); and (3) autotransplants. An appropriateness index was developed based on median rating and amount of disagreement. The relationship of appropriateness indices to the permuted clinical variables was considered by analysis of variance and recursive partitioning. Preference between donor types was analyzed by comparing mean appropriateness indices of comparable settings and a treatment algorithm developed.

CONCLUSIONS

In people with an HLA-identical sibling, this type of transplant was rated appropriate in those with unfavorable cytogenetics and uncertain in all other settings. In people without an HLA-identical sibling, an alternative donor transplant was rated appropriate in those < 30 years with unfavorable cytogenetics, uncertain in those > 30 years and unfavorable cytogenetics and inappropriate in all other settings. Autotransplants were rated appropriate in people with unfavorable cytogenetics and uncertain in all other settings. An HLA-identical sibling donor, when available, was always preferred to an alternative donor transplant or autotransplant. In people without an HLA-identical sibling, an autotransplant was almost always favored over an alternative donor transplant with the magnitude of preference inversely correlated with transplant appropriateness.

Peripheral blood progenitor cell transplantation as an alternative to autologous marrow transplantation in the treatment of acute myeloid leukemia

Herein we report on the feasibility of mobilizing peripheral blood progenitor cells (PBPC) in a prospective study of the HOVON-SAKK Groups in 96 cases with newly diagnosed acute myeloid leukemia (AML). Among 96 patients, 76 patients (79%) entered complete remission. Mobilization was undertaken with variable dosages of G-CSF in 63 patients, and 54 patients (87%) were leukapheresed. The comparative yields of pheresis following the G-CSF schedules and hematopoietic recovery data are presented and discussed. PBPC transplantation results in faster hematopoietic regeneration compared to autologous marrow grafting in the prior AML HOVON study.

CD34 positive blood cells for allogeneic progenitor and stem cell transplantation

The transplantation of allogeneic peripheral blood progenitor cells (PBPC) provides complete and sustained hematopoietic and lymphopoietic engraftment. In healthy donors, large amounts of PBPC can be mobilized with hematopoietic growth factors. However, the high content of immunocompetent T-cells in apheresis products may expose recipients of allogeneic PBPC to an elevated risk of acute and chronic graft-versus-host disease. Thus, the use of appropriate T-cell reduction, but not depletion might reduce this risk. The hazards of graft rejection and a higher relapse rate can be avoided by maintaining a portion of the T-cells in the graft. The positive selection of CD34+ cells from peripheral blood preparations simultaneously provides an approximately 1000-fold reduction of T-cells. These purified CD34+ cells containing committed and pluripotent stem cells are suitable for allogeneic transplantation and can be used in the following instances: 1. As hematopoietic stem and progenitor cell transplantation instead of bone marrow cells, from HLA-identical family donors; 2. for increasing the stem cell numbers from HLA-mismatched or three HLA-loci different family donors in order to reduce the incidence of rejection but without increasing the T-cell number; 3. boosting of poor marrow graft function with stem cells from the same family donors; 4. transplantation from volunteer matched unrelated donors; 5. split transplantation of CD34+ and T-cells; 6. addition of ex vivo expanded CD34+ cells to blood cell or bone marrow transplantation; 7. generation of antigen specific immune effector cells and antigen presenting cells for cell therapy.

High-dose cytosine arabinoside in the treatment of acute myeloid leukaemia

Cytosine arabinoside (Ara-C) has earned its recognition as the most important antileukaemic drug currently available for the treatment of acute myeloid leukaemia. Approximately 60-80% of patients less than 60 years of age can be expected to enter complete remission if treated with standard-dose Ara-C (100-200 mg/m2) in combination with an anthracycline. The efficacy of Ara-C appears clinically to be dose and schedule dependent. A 15-30 fold dose escalation in Ara-C can elicit a therapeutic response in patients who have previously failed treatment with standard-dose Ara-C or other anti-leukaemic drugs. The use of high-dose cytosine arabinoside (HDAC 3 gm/m2) appears rational based on cytosine pharmacology. Drug-scheduling is used to exploit drug synergy when HDAC is given in combination with asparaginase or fludarabine (+/- G-CSF) in a schedule-dependent fashion. Toxicity following Ara-C is also dose- and schedule-dependent. Central nervous system toxicity--particularly cerebellar dysfunction--although rare, is particularly serious because it may preclude further use of the drug. Older patients are particularly susceptible. This article will describe the rationale for and the value of HDAC alone or in combination with other cytotoxics in the treatment of acute myeloid leukaemia.

Autologous bone marrow transplantation for acute myeloid leukemia

Despite progress over the past three decades, most patients with acute myeloid leukemia (AML) treated with conventional chemotherapy alone relapse and die of recurrent leukemia. Treatments used to improve outcome include allogeneic (alloBMT) and autologous bone marrow transplantation (ABMT). Indications for transplantation and the relative merits of alloBMT and ABMT remain unclear. In this review, we evaluate evidence supporting a role of ABMT in AML and compare the results with outcomes after alloBMT. In addition, we discuss areas of controversy including the optimal timing for ABMT, the role of bone marrow purging, the place of peripheral blood stem cell collection, the high dose regimen, and post-transplant immunotherapy to reduce relapse.