Reduced-intensity conditioning for acute myeloid leukemia: is this strategy correct

Targeted in-vitro-stimulation reveals highly proliferative multi-virus-specific human central memory T cells as candidates for prophylactic T cell therapy

Adoptive T cell therapy (ACT) has become a treatment option for viral reactivations in patients undergoing allogeneic hematopoietic stem cell transplantation (alloHSCT). Animal models have shown that pathogen-specific central memory T cells (T_CM) are protective even at low numbers and show long-term survival, extensive proliferation and high plasticity after adoptive transfer. Concomitantly, our own recent clinical data demonstrate that minimal doses of purified (not in-vitro- expanded) human CMV epitope-specific T cells can be sufficient to clear viremia. However, it remains to be determined if human virus-specific T_CM show the same promising features for ACT as their murine counterparts. Using a peptide specific proliferation assay (PSPA) we studied the human Adenovirus- (AdV), Cytomegalovirus- (CMV) and Epstein-Barr virus- (EBV) specific T_CM repertoires and determined their functional and proliferative capacities in vitro. T_CM products were generated from buffy coats, as well as from non-mobilized and mobilized apheresis products either by flow cytometry-based cell sorting or magnetic cell enrichment using reversible Fab-Streptamers. Adjusted to virus serology and human leukocyte antigen (HLA)-typing, donor samples were analyzed with MHC multimer- and intracellular cytokine staining (ICS) before and after PSPA. T_CM cultures showed strong proliferation of a plethora of functional virus-specific T cells. Using PSPA, we could unveil tiniest virus epitope-specific T_CM populations, which had remained undetectable in conventional ex-vivo-staining. Furthermore, we could confirm these characteristics for mobilized apheresis- and GMP-grade Fab-Streptamer-purified T_CM products. Consequently, we conclude that T_CM bare high potential for prophylactic low-dose ACT. In addition, use of Fab-Streptamer-purified T_CM allows circumventing regulatory restrictions typically found in conventional ACT product generation. These GMP-compatible T_CM can now be used as a broad-spectrum antiviral T cell prophylaxis in alloHSCT patients and PSPA is going to be an indispensable tool for advanced T_CM characterization during concomitant immune monitoring.

Impact of age on outcomes of allogeneic hematopoietic stem cell transplantation with reduced intensity conditioning in elderly patients with acute myeloid leukemia

Previous studies have repeatedly reported that increasing age is a significant risk factor for worse outcomes after allogeneic hematopoietic stem cell transplantation (allo-HSCT) among patients with acute myeloid leukemia (AML). However, more recent studies reported conflicting results regarding the association between age and outcomes in elderly patients. Therefore, we conducted a large-scale, nationwide retrospective study to examine the impact of age on outcomes of allo-HSCT with reduced intensity conditioning (RIC) for AML patients who were older than 50 years. Of the 757 patients, 89 patients (11.8%) were 50-54, 249 patients (32.9%) were 55-59, 301 patients (39.8%) were 60-64 and 118 patients (15.6%) were ≥65 years old. The 3-year overall survival (OS) (47.8, 45.2, 37.9, and 36.6% for patients aged 50-54, 55-59, 60-64, and ≥65 years, respectively, P = 0.24) and nonrelapse mortality (NRM) (24.0, 22.8, 29.2, and 27.6% for patients aged 50-54, 55-59, 60-64, and ≥65 years, respectively, P = 0.49) were not significantly different among the four age groups. Multivariate analysis revealed that increased age had no significant effect on OS or NRM after adjusting for covariates. These results suggested that advanced patient age is not a contraindication for RIC allo-HSCT in elderly AML patients.

Intensive chemotherapy and reduced-intensity allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia in elderly patients

AIMS

Acute myeloid leukemia (AML) incidence increases with age, yet treatment of elderly patients has reduced efficacy compared with younger patients and is often poorly tolerated. This retrospective study assessed the outcomes of older patients with AML treated with intensive chemotherapy with or without allogeneic hematopoietic stem cell transplantation (HSCT).

METHODS

We identified all adult patients≥60 years with newly diagnosed AML treated with induction chemotherapy at our institutions between February 1999 and July 2011. Institutional databases and medical records were used to collect information on baseline characteristics, chemotherapy protocols, response to therapy, relapse-free survival (RFS) and overall survival (OS).

RESULTS

Three hundred and forty-five patients≥60 years were diagnosed with AML, including 172 patients (49.9%) who received intensive induction chemotherapy. The median age of intensively treated patients was 66 years (range 60-83 years). Responses to one to two cycles of induction chemotherapy were complete remission (CR) in 70.3% of patients, refractory disease in 15.1% and induction death in 14.5%. At a median follow-up of 22 months for survivors, intensive induction chemotherapy resulted in 3-year RFS of 20.2%, and 3-year OS of 24.0%. Seventeen patients (14.0% of patients in CR1) proceeded to allogeneic HSCT in first remission. These patients experienced 3-year RFS of 63.5% and 3-year OS of 77.5%.

CONCLUSION

Intensive induction chemotherapy for newly diagnosed AML in older patients is feasible and effective in a proportion of patients, and those selected for allogeneic transplantation in CR1 may experience particularly favorable survival outcomes.

Alternative donor transplantation for older patients with acute myeloid leukemia in first complete remission: a center for international blood and marrow transplant research-eurocord analysis

We studied patients with acute myeloid leukemia (AML) over age 50 and in first complete remission (CR1) after adult unrelated donor (URD) (n = 441, 8/8 HLA matched; n = 94, 7/8 HLA matched) or umbilical cord blood (UCB; n = 205) transplantations. UCB recipients achieved CR1 within 8 weeks less often, and received reduced-intensity conditioning and cyclosporine-based graft-versus-host disease (GVHD) prophylaxis more often. Neutrophil recovery was slower in UCB (69% by day 28) compared with 8/8 HLA-matched URD (97%) and 7/8 HLA-matched (91%) (P < .001) recipients. Three-year transplantation-related mortality (TRM) was higher and leukemia-free survival (LFS) lower with UCB (35% and 28%, respectively) versus 8/8 HLA-matched URD (27% and 39%, respectively). TRM was higher in 7/8 HLA-matched URD (41%, P = .01), but LFS was similar at 34% (P = .39). Three-year chronic GVHD was the lowest in UCB (28%) versus 53% and 59% in 8/8 and 7/8 HLA-matched URD recipients, respectively. Three-year survival was 43% in 8/8 HLA-matched URD (95% confidence interval [CI], 38% to 48%), 30% in UCB (95% CI, 23% to 37%) (P = .002) and 37% in 7/8 URD (95% CI, 27 to 46). Allotransplantation for AML in CR1 with any of these grafts extends LFS for over one third of older patients. In the absence of an 8/8 HLA-matched URD or when transplantation is needed urgently, UCB can provide extended survival. Less frequent chronic GVHD with UCB transplantation may be of particular value for older patients.

Reduced-intensity conditioning versus standard conditioning before allogeneic haemopoietic cell transplantation in patients with acute myeloid leukaemia in first complete remission: a prospective, open-label randomised phase 3 trial

BACKGROUND

Reduced-intensity conditioning regimens have been developed to minimise early toxic effects and deaths after allogeneic haemopoietic cell transplantation. However, the efficacy of these regimens before this procedure has not been investigated in a randomised trial. In this prospective, open-label randomised phase 3 trial we compared a reduced-intensity fludarabine-based conditioning regimen with a standard regimen in patients with acute myeloid leukaemia in first complete remission.

METHODS

Patients were aged 18-60 years and had intermediate-risk or high-risk acute myeloid leukaemia (defined by cytogenetics) in first complete remission; an available HLA-matched sibling donor or an unrelated donor with at least nine of ten HLA alleles; and adequate renal, cardiac, pulmonary, and neurological function. Between Nov 15, 2004, and Dec 31, 2009, patients were randomly assigned (1:1, by a computer-based minimisation procedure that balanced patients for age, cytogenetic risk, induction therapy, and donor type) to receive either reduced-intensity conditioning of four doses of 2 Gy of total-body irradiation and 150 mg/m(2) fludarabine or standard conditioning of six doses of 2 Gy of total-body irradiation and 120 mg/kg cyclophosphamide. All patients were given ciclosporin and methotrexate as prophylaxis against graft-versus-host disease. Neither investigators nor patients were blinded to study treatment. Our primary endpoint was the incidence of non-relapse mortality, analysed in the intention-to-treat population. The trial is registered with ClinicalTrials.gov, number NCT00150878.

FINDINGS

The trial was stopped early on Dec 31, 2009, because of slow accrual of patients. 99 patients were randomly assigned to receive reduced-intensity conditioning and 96 to receive standard conditioning. The incidence of non-relapse mortality did not differ between the reduced-intensity and standard conditioning groups (cumulative incidence at 3 years 13% [95% CI 6-21] vs 18% [10-26]; HR 0·62 [95% CI 0·30-1·31]). Relapse incidence (cumulative incidence 3 years 28% [95% CI 19-38] vs 26% [17-36]; HR 1·10 [95% CI 0·63-1·90]), disease-free survival (3 year disease-free survival 58% [95% CI 49-70] vs 56% [46-67]; HR 0·85 [95% CI 0·55-1·32]), and overall survival (3 year overall survival 61% [95% CI 50-74] vs 58% [47-70]; HR 0·77 [95% CI 0·48-1·25]) did not differ significantly between groups. Grade 3-4 of oral mucositis was less common in the reduced-intensity group than in the standard conditioning group (50 patients in the reduced-intensity conditioning group vs 73 patients in the standard conditioning group); the frequency of other side-effects such as graft-versus-host disease and increased concentrations of bilirubin and creatinine did not differ significantly between groups.

INTERPRETATION

Reduced-intensity conditioning results in a similar incidence of non-relapse mortality and reduced toxic effects compared with standard conditioning without affecting survival outcomes, and thus could be preferentially used in patients younger than 60 years with acute myeloid leukaemia transplanted in first complete remission.

Impact of graft-versus-host disease after reduced-intensity conditioning allogeneic stem cell transplantation for acute myeloid leukemia: a report from the Acute Leukemia Working Party of the European group for blood and marrow transplantation

This report investigated the impact of graft-versus-host disease (GVHD) on transplantation outcomes in 1859 acute myeloid leukemia patients given allogeneic peripheral blood stem cells after reduced-intensity conditioning (RIC allo-SCT). Grade I acute GVHD was associated with a lower risk of relapse (hazards ratio (HR)=0.7, P=0.02) translating into a trend for better overall survival (OS; HR=1.3; P=0.07). Grade II acute GVHD had no net impact on OS, while grade III-IV acute GVHD was associated with a worse OS (HR=0.4, P<0.0.001) owing to high risk of nonrelapse mortality (NRM; HR=5.2, P<0.0001). In time-dependent multivariate Cox analyses, limited chronic GVHD tended to be associated with a lower risk of relapse (HR=0.72; P=0.07) translating into a better OS (HR=1.8; P<0.001), while extensive chronic GVHD was associated with a lower risk of relapse (HR=0.65; P=0.02) but also with higher NRM (HR=3.5; P<0.001) and thus had no net impact on OS. In-vivo T-cell depletion with antithymocyte globulin (ATG) or alemtuzumab was successful at preventing extensive chronic GVHD (P<0.001), but without improving OS for ATG and even with worsening OS for alemtuzumab (HR=0.65; P=0.001). These results highlight the role of the immune-mediated graft-versus-leukemia effect in the RIC allo-SCT setting, but also the need for improving the prevention and treatment of severe GVHD.

Common minor histocompatibility antigen discovery based upon patient clinical outcomes and genomic data

Background

Minor histocompatibility antigens (mHA) mediate much of the graft vs. leukemia (GvL) effect and graft vs. host disease (GvHD) in patients who undergo allogeneic stem cell transplantation (SCT) [1], [2], [3], [4]. Therapeutic decision making and treatments [5] based upon mHAs will require the evaluation of multiple candidate mHAs and the selection of those with the potential to have the greatest impact on clinical outcomes. We hypothesized that common, immunodominant mHAs, which are presented by HLA-A, B, and C molecules, can mediate clinically significant GvL and/or GvHD, and that these mHAs can be identified through association of genomic data with clinical outcomes.

Methodology/Principal Findings

Because most mHAs result from donor/recipient cSNP disparities, we genotyped 57 myeloid leukemia patients and their donors at 13,917 cSNPs [6]. We correlated the frequency of genetically predicted mHA disparities with clinical evidence of an immune response and then computationally screened all peptides mapping to the highly associated cSNPs for their ability to bind to HLA molecules. As proof-of-concept, we analyzed one predicted antigen, T4A, whose mHA mismatch trended towards improved overall and disease free survival in our cohort. T4A mHA mismatches occurred at the maximum theoretical frequency for any given SCT. T4A-specific CD8+ T lymphocytes (CTLs) were detected in 3 of 4 evaluable post-transplant patients predicted to have a T4A mismatch.

Conclusions/Significance

Our method is the first to combine clinical outcomes data with genomics and bioinformatics methods to predict and confirm a mHA. Refinement of this method should enable the discovery of clinically relevant mHAs in the majority of transplant patients and possibly lead to novel immunotherapeutics [5].

Graft-versus-disease effect following allogeneic transplantation for acute leukaemia

The graft-versus-leukaemia effect is one of the most important biological effects to influence outcome in patients with acute leukaemia. The recognition of this modality over the past three decades has led to far-reaching changes in the concept and conduct of allogeneic transplantation in acute myeloid leukaemia, and in the infusion of donor lymphocytes as a therapeutic modality. Despite these conceptual advances, there is a considerable need for more structured prospective studies to optimally define the role of reduced-intensity transplantation in both acute myeloid and acute lymphoblastic leukaemia.

Acute myeloid leukemia in the elderly

The incidence of acute myeloid leukemia (AML) is increasing with age. As the results associated with standard intensive chemotherapy remain particularly disappointing in older patients, they represent an ideal target population for clinical and therapeutic investigations. Current attempts are to better define those who may draw a significant benefit from intensive chemotherapy, in order to test new less intensive approaches in the remaining patients. Hopefully, a lot of promising alternative therapies are emerging, including hypomethylating agents, histone deacetylase inhibitors, monoclonal antibodies, or chemotherapeutic agents such as cloretazine or clofarabine. Reduced-intensity conditioning stem cell transplantation or other various immunological approaches represent another way of investigation.

Reduced-intensity conditioning and allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia

Acute myeloid leukemia (AML) is a hematologic malignancy with a peak incidence over the age of 55 years. AML of older patients is less curable with conventional chemotherapy, and, when it relapses, is almost uniformly fatal. Novel treatments hold the promise of improving the results of therapy, but have failed so far to show dramatic change in the prognosis. Allogeneic stem cell transplantation using traditional myeloablative preparative regimens is not easily tolerated by the elderly and/or frailer patient, and may lead to prohibitive treatment-related mortality rates. Most patients treated in the past were younger and devoid of comorbid clinical conditions. Novel reduced-intensity regimens made allogeneic transplants applicable to the elderly, providing the benefit of the graft-versus-leukemia effect to a larger number of patients in need. Here we review the indications for allogeneic transplants in AML and discuss reduced-intensity conditioning regimens.

Hematopoietic transplantation from adult unrelated donors as treatment for acute myeloid leukemia

Transplantation from unrelated donors (URD) is increasingly being used as treatment for hematological malignancies, including acute myeloid leukemia (AML). This increase is the consequence of the availability of more than 11 million URD volunteers and the more efficient donor search process in the recent years. Median time to identify a suitable URD is now 2 months. More than 50% of Caucasian patients have an human leukocyte antigen (HLA)-allele donor match and a one-antigen or allele HLA-mismatched donor may also be acceptable. Complications of URD transplants are particularly frequent and severe, with long-term OS in the registries being 10-20% inferior to HLA-identical sibling transplantation. High resolution DNA techniques for donor and recipient HLA matching have contributed to the survival in experienced centres after unrelated donor SCT approaching that achieved with sibling donors. The introduction of reduced intensity conditioning (RIC) has extended URD transplants to elderly and/or debilitated patients with AML. With this approach, TRM decreases, although graft-versus-host disease-related morbidity and mortality remain a problem. Despite this complication, results after URD transplantation in this age group seem better than those achieved with chemotherapy and/or autologous transplantation. To confirm this possibility, prospective multicenter comparisons of URD transplants after RIC with other treatment options for elderly AML patients have recently been started.

Hematopoietic stem cell transplantation after reduced intensity conditioning in acute myelogenous leukemia patients older than 40 years

Reduced intensity conditioning (RIC) protocols are increasingly used for allogeneic hematopoietic stem cell transplantation (HSCT) in elderly patients. We analyzed the outcome of RIC HSCT in acute myelogenous leukemia (AML) patients over the age of 40 years. Forty-three AML or high-risk myelodysplastic syndrome (MDS) patients were treated with a fludarabine and low-dose total-body irradiation (TBI)-based pretransplantation regimen. Donors were HLA-compatible sibling (68%) or unrelated volunteers (34%). All but 2 AML patients were in complete remission (CR) at the time of transplantation. Seventy-six percent of patients had a poor risk profile. Hematologic recovery was fast, and primary graft failure occurred in 1 patient. Two patients with active disease at the time of HSCT experienced ongoing relapse. Infections were diagnosed in 9 patients (21%), and 6 patients (14%) were treated for cytomegalovirus (CMV) reactivation. Sixty percent of patients developed acute graft-versus-host disease (aGVHD), which was grade II in 40% and grade III in 12%. The cumulative incidence of chronic graft-versus-host disease (cGVHD) was 33% at 1 and at 2 years. Treatment-related mortality (TRM) was low (9%), total nonrelapse mortality (NRM) was 19%. After a median follow-up of 571 days, 16 patients (37%) experienced relapse. Median disease-free and overall survival (DFS; OS) were 24 and 31 months, respectively. There were no differences in complications and outcome between recipients of sibling and unrelated grafts. In conclusion, fludarabine plus low-dose TBI-based RIC HSCT is effective in AML patients over the age of 40 years without active disease at the time of transplant and is associated with low TRM.

Sustained remissions of high-risk acute myeloid leukemia and myelodysplastic syndrome after reduced-intensity conditioning allogeneic hematopoietic transplantation: chronic graft-versus-host disease is the strongest factor improving survival

PURPOSE

Reduced-intensity conditioning (RIC) for allogeneic stem-cell transplantation (allo-SCT) reduces nonrelapse mortality (NRM). This reduction makes it possible for patients who are ineligible for high-dose myeloablative conditioning allo-SCT to benefit from graft-versus-leukemia reaction. In this multicenter, prospective study of patients with acute myeloid leukemia (AML) and high-risk myelodysplastic syndrome (MDS), we investigated the efficacy of RIC allo-SCT from a human leukocyte antigen-identical sibling by using a regimen that uses fludarabine and busulfan.

PATIENTS AND METHODS

Ninety-three patients with AML (n = 59) and MDS (n = 34) were included, and the median age was of 53 years. Follow-up for survivors was 43 months (range, 3 to 89 months). The conditioning regimen consisted of fludarabine (150 mg/m(2)) and oral busulfan (8 to 10 mg/kg). All except one patient received mobilized peripheral blood stem cells. Graft-versus-host disease (GVHD) prophylaxis consisted of cyslosporine and methotrexate or mycophenolate mofetil.

RESULTS

The 100-day, 1-year, and 4-year incidences of NRM were 8, 16%, and 21%, respectively. The 1- and 4-year relapse cumulative incidences were 23% and 37%, respectively, and leukemia recurrence was the main cause of death. The 4-year disease-free survival (DFS) and overall survival (OS) rates were 43% and 45%, respectively. The 4-year cumulative incidence of chronic GVHD was 53% (45% extensive), and its development was the major factor associated with lower relapse incidence and improved DFS and OS.

CONCLUSION

Our results confirm the capacity of this RIC regimen to obtain long-term remissions in patients ineligible for a conventional allo-SCT. The results suggest an important role of the development of chronic GVHD in reducing relapse and improving DFS and OS.

Comparable non-relapse mortality and survival after HLA-identical sibling blood stem cell transplantation with reduced or conventional-intensity preparative regimens for high-risk myelodysplasia or acute myeloid leukemia in first remission

We prospectively compared two strategies of allogeneic PBSCT from HLA-identical siblings in adults with poor-risk AML or myelodysplastic syndrome with >5% marrow blasts in an early disease status (AML or refractory anemia with excess blasts (RAEB type 2) in first remission after chemotherapy or untreated RAEB type 1). Based only on age, all consecutive patients were offered one of two specific transplant protocols. Patients < or =50 years old received conventional high-dose conditioning with cyclophosphamide-TBI and use of CD34+-selected PBSCT (CTCD34+ group), while patients aged >50 years received a reduced-intensity conditioning (RIC) with fludarabine and oral busulphan (FB-RIC). Seventy-five patients entered the study (35 in the CTCD34+ and 39 in the FB-RIC group). The median follow-up was >4 years in both groups. The 4-year non-relapse mortality (NRM) was 19 and 20%, respectively (P=0.8). Relapse and survival were also equivalent in both groups. These results suggest that in this setting, the expected high NRM in elderly patients can be reduced with an RIC regimen.

Reduced intensity conditioning for allogeneic hematopoietic stem cell transplantation in myelodysplastic syndromes and acute myelogenous leukemia

PURPOSE OF REVIEW

The aim of this article is to summarize the outcome in recent studies of patients with acute myelogenous leukemia/myelodysplastic syndromes after reduced intensity conditioning for allogeneic stem cell transplantation.

RECENT FINDINGS

Reduced intensity conditioning has demonstrated the capability to achieve engraftment and to decrease early nonrelapse mortality in older and unfit patients. Most large retrospective studies have demonstrated that reduced intensity conditioning regimens lead to a reduction of nonrelapse mortality in patients with acute myelogenous leukemia and myelodysplastic syndromes, but disease relapse is higher than with standard myeloablative conditioning regimens. Chronic graft-versus-host disease has emerged as one of the more powerful variables reducing relapses and improving overall and disease-free survival. The use of in-vivo T-cell depletion with alemtuzumab or antithymocyte globulin reduces acute graft-versus-host disease but appears to have no impact on survival. Hopefully, a new second generation of reduced intensity conditioning will study new strategies for reducing disease relapse with low nonrelapse mortality.

SUMMARY

Allogeneic stem cell transplantation with reduced intensity conditioning allows many patients considered ineligible for standard myeloablative conditioning to benefit from this therapy. Research must now focus on designing new strategies for reducing the increased risk of disease relapse.

Extended follow-up of methotrexate-free immunosuppression using sirolimus and tacrolimus in related and unrelated donor peripheral blood stem cell transplantation

We assessed the combination of sirolimus and tacrolimus without methotrexate after myeloablative allogeneic stem cell transplantation from 53 matched related donors (MRDs) and 30 unrelated donors (URDs). All patients received cyclophosphamide and total body irradiation conditioning followed by transplantation of mobilized peripheral blood stem cells. The median time to neutrophil engraftment was 14 days. The median time to platelet engraftment was 12 days. No differences between MRD and URD cohorts was noted. The incidence of grade II-IV and III-IV acute graft-versus-host disease (GVHD) were 20.5% and 4.8%. The cumulative incidence of chronic GVHD was 59.1%. There were no differences in acute or chronic GVHD incidence between MRD and URD cohorts. The omission of methotrexate was associated with low transplant-related toxicity, with 30-day and 100-day treatment-related mortality rates of 0% and 4.8%. Relapse-free survival at 1 and 2 years was 72.3% and 68.5%, respectively. Overall survival at 1 and 2 years was 77.1% and 72.2%, respectively. There were no differences in relapse-free or overall survival between MRD and URD cohorts. The substitution of sirolimus for methotrexate as GVHD prophylaxis is associated with rapid engraftment, a low incidence of acute GVHD, minimal transplant-related toxicity, and excellent survival. Differences between MRD and URD cohorts are not evident when effective GVHD prophylaxis is used.

Impact of cytogenetics on outcome of matched unrelated donor hematopoietic stem cell transplantation for acute myeloid leukemia in first or second complete remission

We compared the treatment-related mortality, relapse rate, disease-free survival (DFS), and overall survival (OS) by cytogenetic risk group of 261 patients with acute myeloid leukemia in first complete remission (CR1) and 299 patients in CR2 in undergoing matched unrelated donor hematopoietic stem cell transplantation (HSCT). For patients in first CR, the DFS and OS at 5 years were similar for the favorable, intermediate, and unfavorable risk groups at 29% (95% confidence interval [CI], 8%-56%) and 30% (22%-38%); 27% (19%-39%) and 29% (8%-56%); and 30% (95% CI, 22%-38%) and 30% (95% CI, 20%-41%), respectively. For patients in second CR, the DFS and OS at 5 years were 42% (95% CI, 33%-52%) and 35% (95% CI, 28%-43%); 38% (95% CI, 23%-54%) and 45% (95% CI, 35%-55%); and 37% (95% CI, 30%-45%) and 36% (95% CI, 21%-53%), respectively. Cytogenetics had little influence on the overall outcome for patients in first CR. In second CR, outcome was modestly, but not significantly, better for patients with favorable cytogenetics. The graft-versus-leukemia effect appeared effective, even in patients with unfavorable cytogenetics. However, treatment-related mortality was high. Matched unrelated donor HSCT should be considered for all patients with unfavorable cytogenetics who lack a suitable HLA-matched sibling donor.

Progress and strategies for patients with relapsed and refractory acute myeloid leukemia

PURPOSE OF REVIEW

The treatment of patients with refractory or relapsed acute myeloid leukemia remains challenging. Management of these patients must take into account patient and leukemia-related factors in order to organize a comprehensive approach to treatment. Many new therapies are under study.

RECENT FINDINGS

New molecular markers that represent mutations or gene overexpression have been identified including FMS-like tyrosine kinase-3 and nucleophosmin, which will enhance our ability to more accurately prognosticate for patients with acute myeloid leukemia. Monoclonal antibodies and peptide vaccination with leukemia-associated antigens bring the hope of increasing the remission and cure rates for patients with acute myeloid leukemia. The use of reduced-intensity conditioning blood or marrow transplantation is finding a broader role in the treatment of acute myeloid leukemia.

SUMMARY

Patients with relapsed or refractory acute myeloid leukemia should be entered on clinical trials whenever feasible given the lack of consensus on the most effective treatment in this setting. Blood and marrow transplantation remains the only known curative therapy for these patients and the use of reduced-intensity conditioning blood or marrow transplantation offers the option of this approach to older and more infirm patients. Greater understanding of the biology of acute myeloid leukemia will provide new molecular targets of use in diagnosis, monitoring, and for the development of new, targeted therapies.

Hematopoietic cell transplantation after reduced-intensity conditioning for older adults with acute myeloid leukemia in complete remission

PURPOSE OF REVIEW

Allogeneic hematopoietic cell transplantation with myeloablative conditioning is a well established therapy for patients with acute myeloid leukemia. Its efficacy depends, in part, on the destruction of recipient acute myeloid leukemia cells by the conditioning regimen and, in part on their removal by donor immune cells contained in the graft (graft-versus-tumor effect). Due to regimen-related toxicities, the use of myeloablative allogeneic hematopoietic cell transplantation has been restricted to younger patients in good condition. More recently, the introduction of allogeneic hematopoietic cell transplantation following reduced-intensity or nonmyeloablative conditioning regimens, which rely mainly on graft-versus-tumor effects for tumor cell eradication, has permitted extending hematopoietic cell transplantation to include older patients and those with medical comorbidities.

RECENT FINDINGS

Early results with allogeneic hematopoietic cell transplantation after nonmyeloablative and reduced-intensity conditioning for patients with acute myeloid leukemia in first complete remission are encouraging, with 2-year survivals after hematopoietic cell transplantation ranging from 48 to 79% among studies. Further, retrospective studies have demonstrated similar outcomes in adult patients with acute myeloid leukemia in complete remission given either myeloablative or nonmyeloablative conditioning.

SUMMARY

Prospective studies are needed to define the place of allogeneic hematopoietic cell transplantation after nonmyeloablative or reduced-intensity conditioning in patients with acute myeloid leukemia in complete remission, and to determine a role for consolidation chemotherapy before hematopoietic cell transplantation, if any.

A prospective multicenter trial of peripheral blood stem cell sibling allografts for acute myeloid leukemia in first complete remission using fludarabine-cyclophosphamide reduced intensity conditioning

The role of allogeneic transplantation in patients with de novo acute myeloid leukemia in first complete remission (AML-CR1) is controversial. Aiming to preserve a graft-versus-leukemia effect, but minimize morbidity and mortality from conditioning-related toxicity and graft-versus-host disease (GVHD), we conducted a prospective multicenter study of reduced-intensity conditioning (RIC) as preparation for peripheral blood stem cell sibling allografts in patients with intermediate or poor risk AML-CR1. Conditioning consisted of fludarabine 125 mg/m(2) and cyclophosphamide 120 mg/kg. Thirty-four patients were transplanted with a median age of 45 years; 85% had intermediate risk cytogenetics. Early toxicity was minimal. The overall incidence of grade II-IV acute GVHD was low (21%), but the 3 patients (9%) who developed grade IV GVHD died. Donor T cell chimerism was rapid and generally complete, but complete myeloid chimerism was delayed. Thirteen patients (38%) relapsed, 12 within a year of transplant. The estimated disease-free survival (DFS) and overall survival at 2 years was 56% (95% confidence interval [CI] 39%-71%) and 68% (95% CI 50%-81%), respectively. The incidence of extensive chronic GVHD (cGVHD) was low (24% of surviving patients at 12 months) and most survivors had an excellent performance status. These observations justify a prospective comparison of RIC versus myeloablative conditioning allografts for AML-CR1.

Alternative donor transplants for adult acute lymphoblastic leukaemia: a comparison of the three major options

Myeloablative sibling-matched allogeneic transplantation for adult acute lymphoblastic leukaemia provides the best outcome, but most patients lack a suitable, related histocompatible donor. We reviewed three haematopoietic stem cell donor sources used for alternative donor transplantation pointing out drawbacks of these approaches including inherent selection bias. Matched unrelated donor allografts most often are performed in Philadelphia chromosome-positive disease and in second complete remission (CR2); a nearly 30% event-free survival (EFS) can be anticipated in select patients. Transplants using haploidentical donors are most successful if undertaken in CR1 and CR2 and appear to produce EFS rates of about 25%. Limited umbilical cord blood transplant data suggest efficacy, but marked patient and treatment heterogeneity hamper conclusions. Each of these three strategies has unique potential benefits and disadvantages. The growing use of minimal residual disease detection may identify subgroups of patients unlikely to be cured by chemotherapy alone; these patients are candidates for upfront high-dose chemoradiotherapy and cellular immunotherapy. These three approaches are plagued by treatment-related mortality and relapse rates as high as 40%, but advances in technology and supportive care may make each stem cell source more feasible and efficacious.