Reduced intensity conditioning allows for up-front allogeneic hematopoietic stem cell transplantation after cytoreductive induction therapy in newly-diagnosed high-risk acute myeloid leukemia

Allogeneic hematopoietic cell transplantation for older patients with AML with active disease. A study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT)

Older adults with acute myeloid leukemia (AML) refractory to initial or reinduction chemotherapy have a dismal prognosis if they do not undergo hematopoietic stem-cell transplantation (HCT). However, data assessing HCT outcomes from different donors are scarce. We evaluated results from a retrospective analysis on patients aged ≥70 years, with AML not in remission who received an allogeneic HCT from HLA-matched sibling donor (MSD), HLA-10/10 matched unrelated donor (MUD), or T-cell replete haploidentical (Haplo) donor, from 2010 to 2021, reported to the ALWP-EBMT database. A total of 360 patients (median age 72 years, range 70-79) were included in the analysis. Median follow-up for the entire population was 35.5 months. Donors were MSD (n = 58), 10/10 HLA-MUD (n = 228), and Haplo (n = 74). A total of 213 (59.2%) patients were primary induction failures, while 147 (40.8%) were in first or subsequent relapse. Graft source was peripheral blood in 92% of the patients. Patients transplanted from Haplo donors more frequently received marrow grafts (p < 0.01) and presented the combination female donor to male recipient (p < 0.01). The overall 2-year rates of overall survival (OS) and leukemia-free survival (LFS) were: 62.4% (95% CI 47.2-74.3) and 47.6% (95% CI 33.1-60.8) for MSD, 43% (95% CI 35.8-49.9), and 37.5% (95% CI 30.7-44.4) for MUD, and 25.9% (95% CI 15.8-37.2), and 26.5% (95% CI 16.3-37.8) for recipients of Haplo transplants. The 2-year cumulative incidence of relapse (RI) was slightly lower for Haplo recipients at 29.6% (95% CI 19-40.9), for MUD it was 30.2% (95% CI 23.9-36.7), and for MSD 34.9% (95% CI 22-48.2); counterbalanced by a higher incidence of non-relapse mortality (NRM) of 43.9% (95% CI 31.6-55.6) for Haplo recipients, 32.2% (95% CI 26-33.1) for MUD and 17.5% (95% CI 8.4-29.3) for MSD. Graft-versus-host disease (GVHD-free, relapse-free survival (GRFS) was 35.3% (95% CI 22.3-48.5) for MSD, 29.6% (95% CI 23.2-36.2) for MUD, and 19.2% (95% CI 10.7-29.6) for Haplo patients. In the multivariate model, compared to the referent group of MSD recipients, the risk of NRM was higher among patients transplanted from Haplo donors ([hazard ratio] HR 5.1, 95% CI 2.23-11.61, p < 0.001) and MUD (HR 3.21, 95% CI 1.48-0.6.94, p = 0.003). Furthermore, both Haplo and MUD were associated with inferior OS, (HR 3.6, 95% CI 1.98-0.6.56, p < 0.001, and HR 2.3, 95% CI 1.37-0.3.88, p = 0.002, respectively), and LFS (HR 2.24, 95% CI 1.31-0.3.84, p = 0.003, and HR 1.64, 95% CI 1.04-0.2.60, p = 0.034, respectively). Patients transplanted from Haplo donors were also associated with worse GFRS (HR 1.72, 95% CI 1.07-2.77, p:0.025) compared with MSD patients. Older adult AML patients with active disease transplanted from MSD experienced prolonged OS and LFS compared to 10/10 MUD and Haplo due to lower NRM. Prospective clinical trials are warranted.

Allogeneic Stem Cell Transplantation with Sequential Melphalan-Based Conditioning in AML: Residual Morphological Blast Count Determines the Risk of Relapse

Introduction

Allogeneic hematopoietic cell transplantation (HCT) during chemotherapy-induced aplasia may offer long-term survival in acute myeloid leukemia (AML) with otherwise poor prognosis including ELN adverse risk, relapsed or refractory disease. However, the value of residual morphologic disease prior HCT in this context has not been conclusively settled until yet. Therefore, we aimed to investigate variables predicting outcome in this unique setting of sequential conditioning therapy, with a focus on pretreatment morphologic blast count. In contrast to the most popular FLAMSA-RIC protocol, we used a melphalan-based conditioning regimen during aplasia.

Methods

We retrospectively analyzed data from 173 AML patients who underwent a sequential melphalan-based conditioning therapy between 2003 and 2015 at our centre. All patients participated either in the prospective Phase 2 BRIDGE trial (NCT01295307), the Phase 3 AML2003 study (NCT00180102) or were treated according to this protocol and underwent allogeneic HCT after melphalan-based conditioning in treatment-induced aplasia.

Results

Median bone marrow blast count prior to conditioning was 10% (range, 0–96%). Four year probabilities of EFS and OS were 34% (95% CI, 28–43%) and 43% (95% CI, 36–52%), respectively. In multivariate analysis, blast count >20% was associated with worse EFS (HR = 1.93; p = 0.009) and OS (HR = 1.80; p = 0.026). This effect was not significant anymore for HCT during 1st line therapy.

Conclusion

Allogeneic HCT in aplasia with a melphalan-based conditioning regimen has the potential to cure a subset of adverse risk AML patients, even with persistent morphological disease prior HCT. However, a high pre-transplant blast count still indicates patients with a dismal prognosis, especially in the relapsed patient group, for whom post-transplant strategies should be considered to further optimize post HCT outcome.

Allogeneic hematopoietic cell transplantation in chemotherapy-induced aplasia in children with high-risk acute myeloid leukemia or myelodysplasia

Relapse remains the most common cause of treatment failure after hematopoietic cell transplantation for acute myeloid leukemia. Inability to achieve hematologic complete remission has been a barrier to transplant for patients with refractory disease. We describe six children with refractory myeloid disease undergoing transplant in chemotherapy-induced aplasia, as a strategy to facilitate curative therapy in refractory patients. Clofarabine- or high-dose cytarabine-based chemotherapy regimens were used to achieve marrow aplasia, followed by reduced-intensity conditioning and allogeneic transplant before hematologic recovery. Long-term disease control was achieved in five, with one transplant-related mortality, suggesting the feasibility of this approach.

Durable graft-versus-leukaemia effects without donor lymphocyte infusions - results of a phase II study of sequential T-replete allogeneic transplantation for high-risk acute myeloid leukaemia and myelodysplasia

Allogeneic haematopoietic stem-cell transplantation remains the only curative treatment for relapsed/refractory acute myeloid leukaemia (AML) and high-risk myelodysplasia but has previously been limited to patients who achieve remission before transplant. New sequential approaches employing T-cell depleted transplantation directly after chemotherapy show promise but are burdened by viral infection and require donor lymphocyte infusions (DLI) to augment donor chimerism and graft-versus-leukaemia effects. T-replete transplantation in sequential approaches could reduce both viral infection and DLI usage. We therefore performed a single-arm prospective Phase II clinical trial of sequential chemotherapy and T-replete transplantation using reduced-intensity conditioning without planned DLI. The primary endpoint was overall survival. Forty-seven patients with relapsed/refractory AML or high-risk myelodysplasia were enrolled; 43 proceeded to transplantation. High levels of donor chimerism were achieved spontaneously with no DLI. Overall survival of transplanted patients was 45% and 33% at 1 and 3 years. Only one patient developed cytomegalovirus disease. Cumulative incidences of treatment-related mortality and relapse were 35% and 20% at 1 year. Patients with relapsed AML and myelodysplasia had the most favourable outcomes. Late-onset graft-versus-host disease protected against relapse. In conclusion, a T-replete sequential transplantation using reduced-intensity conditioning is feasible for relapsed/refractory AML and myelodysplasia and can deliver graft-versus-leukaemia effects without DLI.

The Superiority of Allogeneic Hematopoietic Stem Cell Transplantation Over Chemotherapy Alone in the Treatment of Acute Myeloid Leukemia Patients with Mixed Lineage Leukemia (MLL) Rearrangements

BACKGROUND Acute myeloid leukemia (AML) patients with mixed lineage leukemia (MLL) gene rearrangements always had a very poor prognosis. In this study, we report the incidence of MLL rearrangements in AML patients using gene analysis, as well as the clinical significance and prognostic features of these rearrangements. MATERIAL AND METHODS This retrospective study took place from April 2008 to November 2011 in the People's Liberation Army General Hospital. A total 433 AML patients were screened by multiple nested reverse transcription polymerase chain reaction (RT-PCR) to determine the incidence of the 11 MLL gene rearrangements. There were 68 cases of MLL gene rearrangements, for a positive rate of 15.7%. A total of 24 patients underwent allogeneic hematopoietic stem cell transplantation (Allo-HSCT), and 34 patients received at least 4 cycles of chemotherapy. Ten patients were lost to follow-up. RESULTS The median follow-up was 29 months. The complete remission (CR) rate was 85.4%. The overall survival (OS) was 57.4±5.9 months for the Allo-HSCT group and 21.0±2.1 months for the chemotherapy group. The Allo-HSCT group had superior survival compared with the chemotherapy group (5-year OS: 59±17% vs. 13±8%, P<0.01; 5-year disease-free survival [DFS]: 65±10% vs. 40±16%, P>0.05). Multivariate analysis showed that transplantation, platelets >50×10^9/L at onset, and CR are associated with a better OS in MLL rearranged AML patients. Patients with thrombocytopenia and extramedullary involvement were prone to relapse. CONCLUSIONS Our results suggest that Allo-HSCT is superior to chemotherapy alone for treating MLL rearranged AML patients. Patients treated with Allo-HSCT have a better prognosis and a longer survival. CR is an independent prognostic factor for OS, and extramedullary involvement is an independent prognostic factor for DFS. MLL rearranged AML patients with thrombocytopenia at onset <50×10^9 had very bad OS and DFS.

Clofarabine salvage therapy before allogeneic hematopoietic stem cell transplantation in patients with relapsed or refractory AML: results of the BRIDGE trial

In patients with relapsed or refractory (r/r) acute myeloid leukemia (AML), long-term disease control can only be achieved by allogeneic hematopoietic stem cell transplantation (HSCT). We studied the safety and efficacy of clofarabine-based salvage therapy. The study was designed as phase II, multicenter, intent-to-transplant (ITT) study. A total of 84 patients with r/r AML were enrolled. All patients received at least one cycle of CLARA (clofarabine 30 mg/m(2) and cytarabine 1 g/m(2), days 1-5). Chemo-responsive patients with a donor received HSCT in aplasia after first CLARA. Generally, HSCT was performed as soon as possible. The conditioning regimen consisted of clofarabine (4 × 30 mg/m(2)) and melphalan (140 mg/m(2)). The median patient age was 61 years (range 40-75). On day 15 after start of CLARA, 26% of patients were in a morphologically leukemia-free state and 79% exposed a reduction in bone marrow blasts. Overall, 67% of the patients received HSCT within the trial. The primary end point, defined as complete remission after HSCT, was achieved by 60% of the patients. According to the ITT, overall survival at 2 years was 43% (95% confidence interval (CI), 32-54%). The 2-year disease-free survival for transplanted patients was 52% (95% CI, 40-69%). Clofarabine-based salvage therapy combined with allogeneic HSCT in aplasia shows promising results in patients with r/r AML.

Busulfan and fludarabine conditioning regimen given at hematological nadir of cytoreduction fludarabine, cytarabine, and idarubicin chemotherapy in patients with refractory acute myeloid leukemia undergoing allogeneic stem cell transplantation: a single arm pilot consort study

To improve the outcome of allogeneic stem cell transplantation in refractory acute myeloid leukemia (AML), we conducted a single-arm phase II clinical trial to evaluate the efficacy and feasibility of conditioning regimen following cytoreduction chemotherapy with 7-day interval. Adult patients with refractory AML were enrolled in the study and received fludarabine, cytarabine, and idarubicin (FLAG-IDA) as cytoreductive chemotherapy followed by busulfan and fludarabine (Flu-BU) conditioning regimen and transfusion of mobilized peripheral stem cells from human leukocyte antigen-matched sibling or unrelated donor. The primary endpoint of the study was 2-year leukemia-free survival (LFS) and secondary endpoints included complete-remission rate, 2-year overall survival (OS), nonrelapse mortality (NRM), and relapse rate. A total of 16 patients were enrolled with median age of 36 (16-60), which included 9 primary induction failure, 2 early relapse, and 5 with relapse/refractory disease. The median cycles of previous chemotherapy were 4 (3-10) with a median of 55% (1%-90%) blasts in bone marrow. Six patients received transplantation from matched sibling and 10 from matched unrelated donors. After transplantation, 15 patients achieved bone marrow remission (11 complete remissions [CRs] and 4 bone marrow remissions without platelet recovery) at day +28. A total of 8 patients remained alive in CR with median LFS of 29.5 months (9.5-40.5 months). Four patients relapsed and 3 of them died of disease and another 4 patients died because of transplantation-related toxicity. The 2-year NRM and relapse rates were 25.0% ± 10.8% and 33.4% ± 13.8%, respectively with 2-year OS at 53.5% ± 13.1% and LFS at 50.0% ± 12.5%. Based on the Simon 2-stage design, 5 out of first eligible 14 patients remained leukemia-free for more than 2 years after allogeneic hematopoietic stem cell transplantation; thus, the null hypothesis of the study will be rejected and the study protocol is accepted as being warranted for further study. Based on the above data, our phase II study demonstrated that the sequential FLAG-IDA cytoreduction chemotherapy followed by Flu-BU conditioning regimen given at the hematological nadir was feasible and has sufficient activity to warrant further investigation prospectively with a larger patient sample (clinicaltrials.gov identifier: NCT01496547).

Hematopoietic cell transplantation in patients with intermediate and high-risk AML: results from the randomized Study Alliance Leukemia (SAL) AML 2003 trial

The optimal timing of allogeneic hematopoietic stem cell transplantation (HCT) in acute myeloid leukemia (AML) is controversial. We report on 1179 patients with a median age of 48 years who were randomized upfront. In the control arm, sibling HCT was scheduled in the first complete remission for intermediate-risk or high-risk AML and matched unrelated HCT in complex karyotype AML. In the experimental arm, matched unrelated HCT in first remission was offered also to patients with an FLT3-ITD (FMS-like tyrosine kinase 3-internal tandem duplication) allelic ratio >0.8, poor day +15 marrow blast clearance and adverse karyotypes. Further, allogeneic HCT was recommended in high-risk AML to be performed in aplasia after induction chemotherapy. In the intent-to-treat (ITT) analysis, superiority of the experimental transplant strategy could not be shown with respect to overall survival (OS) or event-free survival. As-treated analyses suggest a profound effect of allogeneic HCT on OS (HR 0.73; P=0.002) and event-free survival (HR 0.67; P<0.001). In high-risk patients, OS was significantly improved after allogeneic HCT in aplasia (HR 0.64; P=0.046) and after HCT in remission (HR 0.74; P=0.03). Although superiority of one study arm could not be demonstrated in the ITT analysis, secondary analyses suggest that early allogeneic HCT is a promising strategy for patients with high-risk AML.

Clofarabine/cyclophosphamide for debulking before stem cell transplantation

BACKGROUND

Allogeneic haematopoietic stem cell transplantation (HSCT) is the only curative rescue therapy for patients (pts) with chemotherapy-refractory acute leukaemia. Disease control prior to HSCT is essential for long-term disease-free survival after HSCT.

PATIENTS AND METHODS

We have retrospectively analysed the outcome of 20 pts aged 21-64 years with refractory leukaemia (acute myeloid leukaemia, n = 16; acute lymphatic leukaemia, n = 4) who received debulking therapy with clofarabine (10 mg/m², days 1-4) and cyclophosphamide (200 mg/m², days 1-4; ClofCy) prior to HSCT.

RESULTS

Clofarabine/cyclophosphamide (1-4 cycles) was well tolerated and resulted in a substantial reduction of leukaemic cells in all pts. HSCT was performed in 15 of 20 pts. After HSCT (myeloablative, n = 9; dose-reduced, n = 6), all pts showed engraftment and full donor chimerism (related donors, n = 4 or unrelated donors, n = 11) and all pts achieved complete haematologic remission (CR). The median survival after HSCT is 531 days (range: 48-1462 days), and six pts are still alive after a median of 1245 days. Seven pts died after they had relapsed between days +152 and +1496. One patient died from acute graft-versus-host disease (day +48) and one from systemic fungal infection (day +87).

CONCLUSION

Clofarabine/cyclophosphamide is a novel effective treatment approach for pts with chemotherapy-refractory acute leukaemia prior to HSCT. Whether this novel debulking protocol leads to improved long-term outcome in pts with refractory leukaemias remains to be determined in forthcoming clinical studies.

Design of a cost-effectiveness analysis alongside a randomized trial of transplantation using umbilical cord blood versus HLA-haploidentical related bone marrow in advanced hematologic cancer

BACKGROUND

BMT CTN 1101 is a Phase III randomized controlled trial evaluating the comparative effectiveness of double unrelated umbilical cord blood (dUCB) versus HLA-haploidentical related donor bone marrow (haplo-BM) donor cell sources for blood or bone marrow transplantation (BMT) in patients with hematologic malignancies. Herein, we present the rationale, design and methods of the first cost-effectiveness analysis to be conducted alongside a BMT trial.

METHODS

Consenting patients will provide health insurance information to allow calculation of direct medical costs from reimbursement records, and will provide out-of-pocket costs, time costs and health-related quality of life measures through an online survey. These outcomes will inform a cost-effectiveness analysis comparing dUCB and haplo-BM donor cell sources from patient, payer and societal perspectives.

CONCLUSION

Novel approaches may significantly change the cost, outcomes or availability of BMT. The results of this analysis will be the first to provide a comprehensive evaluation of the comparative effectiveness of these approaches from multiple perspectives.

Treatment of acute myeloid leukemia in older patients

Acute myeloid leukemia carries a dismal prognosis in patients over 60 years of age and, despite many clinical trials of both novel and conventional agents, there has been no significant improvement in overall survival during the last 30 years. Combinations of anthracyclines and cytarabine remain the cornerstone of therapy and produce complete remission in 45-55% of older patients, with a median survival of only 8-12 months. These statistics become even worse in patients over 70 years and those with unfavorable cytogenetics and/or poor performance status. Deciding which older acute myeloid leukemia patients would benefit from intensive chemotherapy is difficult and efforts are underway to improve existing risk-assessment tools. Many new agents are under development, including signal transduction inhibitors, farnesyl transferase inhibitors, antibodies and novel chemotherapeutics. To date, small-molecule inhibitors and targeted therapies have had limited single-agent efficacy and have required combination with chemotherapy. The role of hematopoietic stem cell transplantation in older patients is under investigation. All patients over 60 years of age with acute myeloid leukemia should be encouraged to participate in a clinical trial if possible.

A novel clofarabine bridge strategy facilitates allogeneic transplantation in patients with relapsed/refractory leukemia and high-risk myelodysplastic syndromes

Patients with relapsed/refractory leukemias or advanced myelodysplastic syndrome (MDS) fare poorly following allogeneic hematopoietic cell transplant (HCT). We report prospective phase II study results of 29 patients given clofarabine 30 mg/m(2)/day i.v. × 5 days followed immediately by HCT conditioning while at the cytopenic nadir. A total of 15/29 patients (52%) were cytoreduced according to pre-defined criteria (cellularity <20% and blasts <10%). Marrow cellularity (P<0.0001) and blast% (P=0.03) were reduced. Toxicities were acceptable, with transient hyperbilirubinemia (48%) and gr3-4 infections (10%). In all, 28/29 proceeded to transplant; 27 received ATG or alemtuzumab. Post HCT, 180 day non-relapse mortality (NRM) was 7% (95% confidence interval (CI): 1-21), relapse was 29% (95% CI: 13-46) and OS was 71% (95% CI: 51-85), comparing favorably to published data for high-risk patients. Two-year graft vs host disease incidence was 40% (95% CI: 21-58) and 2 year OS was 31% (95% CI: 14-48). Disease at the nadir correlated with inferior OS after HCT (HR=1.22 for each 10% marrow blasts, 95% CI: 1.02-1.46). For AML/MDS patients, there was a suggestion that successful cytoreduction increased PFS (330 vs 171 days, P=0.3) and OS (375 vs 195 days, P=0.31). Clofarabine used as a bridge to HCT reduces disease burden, is well tolerated, and permits high-risk patients to undergo HCT with acceptable NRM. Late relapses are common; thus, additional strategies should be pursued. NCT-00724009.

Who benefits from allogeneic transplantation for myelodysplastic syndromes?: new insights

Recently, a refined cytogenetic and molecular classification fundamentally changed the prognostication of patients with myelodysplastic syndromes (MDS). The increasingly complex heterogeneity of this disease entity is mirrored by life expectancy rates ranging from almost a decade for very low-risk disease down to several months in higher-risk patients, even with conventional treatments. Intensive treatment approaches are hampered by the older age of most of the patients, potentially leading to an unacceptable adverse event rate. This is especially true for allogeneic hematopoietic stem cell transplantation (HCT), which, albeit of curative intent, can lead to considerable morbidity and mortality mostly as a result of organ toxicity, infectious complications, and GVHD. Furthermore, innovative drug developments, including hypomethylating agents, have broadened the therapeutic armamentarium and, although not curative, can lead to durable responses in subgroups of patients with higher-risk MDS. In fact, there is still no prospective randomized trial available that formally demonstrates the benefit of allogeneic HCT compared with standard treatments in MDS patients. In the absence of randomized data, when considering allogeneic HCT, emphasis should be put on patient selection and optimization of the pre- and posttransplantation treatment period. In these patients, a thorough comorbidity evaluation is mandatory and stratification according to age, cytogenetics, cytopenias, disease-related quality of life, and available alternative treatments should be performed in deciding whether, when, and how to perform allogeneic HCT.

Outcome of high-risk acute myeloid leukemia after allogeneic hematopoietic cell transplantation: negative impact of abnl(17p) and −5/5q−

The European LeukemiaNet classification combines a heterogeneous group of aberrations as adverse-risk abnormalities. Our goal was to investigate the outcomes associated with distinct high-risk chromosomal abnormalities in acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation (HSCT). We performed a retrospective cohort analysis in patients with high-risk AML who received first, HLA-compatible, allogeneic HSCT between January 2005 and December 2008. Data from 236 patients with a median age of 55 years were included. Because complex karyotype (CK), −5/5q−, and abnl(17p) are overlapping categories, a hierarchical classification system based on the presence or absence of abnl(17p) and −5/5q− was developed. Patients with abnl(17p) had a 2-year event-free survival (EFS) of 11% (95% confidence interval [CI], 0%-25%), patients with −5/5q− but no abnl(17p) a 2-year EFS of 29% (95% CI, 14%-44%), and patients with adverse-risk AML but neither of the 2 marker lesions a 2-year EFS of 49% (95% CI, 39%-59%). Notably, complex and monosomal karyotypes lost their prognostic value when these marker lesions were excluded. In conclusion, hierarchical classification of adverse-risk karyotypes by 2 marker lesions, abnl(17p) and −5/5q−, is effective in prognostication of the outcome of allogeneic HSCT in AML.

Prognostic factors affecting outcome after allogeneic transplantation for hematological malignancies from unrelated donors: results from a randomized trial

Several prognostic factors for the outcome after allogeneic hematopoietic stem-cell transplant (HSCT) from matched unrelated donors have been postulated from registry data; however, data from randomized trials are lacking. We present analyses on the effects of patient-related, donor-related, and treatment-related prognostic factors on acute GVHD (aGVHD), chronic GVHD (cGVHD), relapse, nonrelapse mortality (NRM), disease-free survival (DFS), and overall survival (OS) in a randomized, multicenter, open-label, phase III trial comparing standard graft-versus-host-disease (GVHD) prophylaxis with and without pretransplantation ATG-Fresenius (ATG-F) in 201 adult patients receiving myeloablative conditioning before HSCT from HLA-A, HLA-B antigen, HLA-DRB1, HLA-DQB1 allele matched unrelated donors. High-resolution testing (allele) of HLA-A, HLA-B, and HLA-C were obtained after study closure, and the impact of an HLA 10/10 4-digit mismatch on outcome and on the treatment effect of ATG-F versus control investigated. Advanced disease was a negative factor for relapse, DFS, and OS. Donor age ≥40 adversely affected the risk of aGVHD III-IV, extensive cGVHD, and OS. Younger donors are to be preferred in unrelated donor transplantation. Advanced disease patients need special precautions to improve outcome. The degree of mismatch had no major influence on the positive effect of ATG-F on the reduction of aGVHD and cGVHD.

Reduced-intensity conditioning transplantation in acute leukemia: the effect of source of unrelated donor stem cells on outcomes

We report the relative efficacy of co-infusing 2 umbilical cord blood units (dUCB) compared with peripheral blood progenitor cells (PBPCs) from 8 of 8 or 7 of 8 HLA-matched unrelated donors. All patients received reduced-intensity conditioning (RIC) regimens. Four treatment groups were evaluated: 4-6 of 6 matched dUCB-TCF (n = 120; TCF = total body irradiation [TBI] 200 cGy + cyclophosphamide + fludarabine), 4-6 of 6 matched dUCB-other (n = 40; alkylating agent + fludarabine ± TBI), and 8 of 8 (n = 313) and 7 of 8 HLA-matched PBPCs (n = 111). Compared with matched 8 of 8 PBPC transplantations, transplantation-related mortality (TRM), and overall mortality were similar after dUCB-TCF (relative risk [RR] 0.72, P = .72; RR 0.93, P = .60) but higher after dUCB-other RIC (hazard ratio [HR] 2.70, P = .0001; 1.79 P = .004). Compared with 7 of 8 PBPC transplantations, TRM (but not overall mortality) was lower after dUCB-TCF (RR 0.57, P = .04; RR 0.87 P = .41). The probabilities of survival after dUCB-TCF, dUCB-other RIC, and 8 of 8 PBPC and 7 of 8 PBPC transplantations were 38%, 19%, 44%, and 37%, respectively. With similar survival after 8 of 8, 7 of 8 matched PBPCs, and dUCB-TCF, these data support use of dUCB-TCF transplantation in adults with acute leukemia who may benefit from RIC transplantation urgently or lack a 7-8 of 8 unrelated donor.

Reduced-Intensity Conditioning Allogeneic Hematopoietic Cell Transplantation in Adults with Acute Myeloid Leukemia

Background

Acute myeloid leukemia (AML), whether de novo or arising from antecedent hematologic disorders in elderly patients, is less likely to be curable with standard chemotherapy regimens used for younger patients. Allogeneic hematopoietic cell transplantation (alloHCT) is currently the most efficient anti-leukemia treatment for AML and has shown a survival advantage in younger patients with intermediate- or poor-risk cytogenetics.

Methods

The authors review their experience as well as the published data regarding the role of reduced-intensity conditioning (RIC) alloHCT in adults with AML. MEDLINE/PubMed and EMBASE/Ovid were searched, as well as reference lists of relevant articles, conference proceedings, and ongoing trial databases.

Results

Elderly patients with AML have a poor survival for all cytogenetics subgroups (except for acute promyelocytic leukemia) and higher rates of transplant-related mortality with myeloablative alloHCT. RIC regimens have been shown to decrease procedure-related toxicity and have emerged as an attractive treatment modality in AML patients not suitable for myeloablative conditioning regimens. While prospective data comparing outcomes of AML patients undergoing RIC alloHCT vs conventional chemotherapy alone are not yet available, RIC alloHCT is a reasonable option for high-risk older patients and for younger AML patients with medical comorbidities who achieve a first or subsequent remission. The application of RIC for patients with refractory disease or untreated relapse as well as the use of alternative donors should be considered within the context of clinical trials.

Conclusions

RIC alloHCT is a safe and effective treatment modality in high-risk elderly AML patients and in younger AML patients with medical comorbidities.

Alternative donor transplantation after reduced intensity conditioning: results of parallel phase 2 trials using partially HLA-mismatched related bone marrow or unrelated double umbilical cord blood grafts

The Blood and Marrow Transplant Clinical Trials Network conducted 2 parallel multicenter phase 2 trials for individuals with leukemia or lymphoma and no suitable related donor. Reduced intensity conditioning (RIC) was used with either unrelated double umbilical cord blood (dUCB) or HLA-haploidentical related donor bone marrow (Haplo-marrow) transplantation. For both trials, the transplantation conditioning regimen incorporated cyclophosphamide, fludarabine, and 200 cGy of total body irradiation. The 1-year probabilities of overall and progression-free survival were 54% and 46%, respectively, after dUCB transplantation (n = 50) and 62% and 48%, respectively, after Haplo-marrow transplantation (n = 50). The day +56 cumulative incidence of neutrophil recovery was 94% after dUCB and 96% after Haplo-marrow transplantation. The 100-day cumulative incidence of grade II-IV acute GVHD was 40% after dUCB and 32% after Haplo-marrow transplantation. The 1-year cumulative incidences of nonrelapse mortality and relapse after dUCB transplantation were 24% and 31%, respectively, with corresponding results of 7% and 45%, respectively, after Haplo-marrow transplantation. These multicenter studies confirm the utility of dUCB and Haplo-marrow as alternative donor sources and set the stage for a multicenter randomized clinical trial to assess the relative efficacy of these 2 strategies. The trials are registered at www.clinicaltrials.gov under NCT00864227 (BMT CTN 0604) and NCT00849147 (BMT CTN 0603).

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.

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.

Feasibility of clofarabine cytoreduction before allogeneic transplant conditioning for refractory AML

To control disease before allogeneic hematopoietic cell transplantation (HCT) for relapsed/refractory AML, we used clofarabine cytoreduction. Seventeen patients received clofarabine 30-40  mg/m(2) i.v. daily for 5 days with plans to initiate conditioning during the nadir, 14 days later. Bone marrow biopsy 12 days after clofarabine showed effective cytoreduction (that is,<20% cellularity with <10% blasts) in 10 of 17 patients (59%). Ineffective cytoreduction correlated with lower PFS (3.8 vs 6.4 months; HR=2.7, 95% CI=1.10-14.29, P=0.035) and OS (5.1 vs 16.6 months; HR=2.5, 95% CI=0.98-12.17, P=0.053). Significant toxicities before HCT, attributable to clofarabine, were grade 1-2 hyperbilirubinemia (18%); grade 1-2 (59%) or grade 3-4 (18%) transaminitis; and grade 1-2 (18%) creatinine elevation. Sixteen patients proceeded to HCT infusion 22 days (median) after initiation of clofarabine. Day 100 and 2-year transplant-related mortality were 6 and 36%. Nine patients relapsed. One year PFS and OS were 25 and 38%, respectively. Two patients are alive in remission at 18 and 52 months. Clofarabine cytoreduction followed by immediate HCT is feasible with acceptable toxicity and TRM. Outcomes for this cohort of patients with refractory AML remain poor and we are studying this approach in a prospective manner.

TLI and ATG conditioning with low risk of graft-versus-host disease retains antitumor reactions after allogeneic hematopoietic cell transplantation from related and unrelated donors

A hematopoietic cell transplantation regimen was adapted from a preclinical model that used reduced-intensity conditioning (RIC) and protected against graft-versus-host disease (GVHD) by skewing residual host T-cell subsets to favor regulatory natural killer T cells. One hundred eleven patients with lymphoid (64) and myeloid (47) malignancies received RIC using total lymphoid irradiation (TLI) and antithymocyte globulin (ATG) followed by the infusion of granulocyte colony-stimulating factor-mobilized grafts. Included were 34 patients at least 60 years of age, 32 patients at high risk of lymphoma relapse after disease recurrence following prior autologous transplantation, and 51 patients at high risk of developing GVHD due to lack of a fully human leukocyte antigen (HLA)-matched related donor. Durable chimerism was achieved in 97% of patients. Cumulative probabilities of acute GVHD (grades II-IV) were 2 and 10% of patients receiving related and unrelated donor grafts. Nonrelapse mortality (NRM) at 1 year was less than 4%. Cumulative incidence of chronic GVHD was 27%. The 36-month probability of overall and event-free survival was 60% and 40%, respectively. Disease status at start of conditioning and the level of chimerism achieved after transplantation significantly impacted clinical outcome. The high incidence of sustained remission among patients with active disease at time of transplantation suggests retained graft-versus-tumor reactions. Active trial registration currently at clinicaltrials.gov under IDs of NCT00185640 and NCT00186615.

Prediction of duration and success rate of unrelated hematopoietic stem cell donor searches based on the patient's HLA-DRB1 allele and DRB1-DQB1 haplotype frequencies

Rapid identification of a matched unrelated donor is essential for patients in need of hematopoietic SCT. We carried out a retrospective evaluation of 549 unrelated donor searches (UDSs), which were completed in 2005 for 23 German transplant centers. On the basis of the patient's HLA-DRB1 allele and DRB1-DQB1 haplotype frequencies, UDSs were divided into four groups with different search success probability predictions. For 90.5% of the patients, an acceptable HLA-matched, and for 61.6% an HLA-A-B-Cw-DRB1-DQB1-identical (10/10 matched) unrelated donor was found. The median search duration was 22 days. In the groups with high (n = 318), medium (n = 157), low (n = 56) and very low (n = 18) UDS success probability, an acceptable donor was found for 99.1, 86.6, 75.0 and 22.2% of the patients, and a 10/10-matched donor was found for 78.3, 49.7, 17.9 and 4.5% of the patients, respectively. The median search duration was 20, 27, 45 and 477 days in the groups with high, medium, low and very low probability, respectively. The search success rate and duration can be predicted on the basis of the patient's HLA-DRB1 allele and HLA-DRB1-DQB1 haplotype frequencies. An unrelated donor can be found for most of the patients, even if the indication for transplantation is urgent.

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.

Allogeneic stem cell transplantation in acute myeloid leukemia: establishment of indications on the basis of individual risk stratification

INTRODUCTION

Acute myeloid leukemia (AML) is a heterogeneous disorder with subtypes that differ considerably in morphology and in their underlying chromosomal and molecular aberrations, which, in turn, determine their prognosis. The establishment of the indications for allogeneic stem cell transplantation (SCT) therefore requires individualized risk stratification based on a combination of multiple diagnostic methods, including cytogenetic and molecular genetic studies, and immunophenotyping, as well as the sensitivity of the disease to chemotherapy.

METHODS

This article surveys the current strategies for establishing the indications for SCT in AML on the basis of a selective review of the relevant literature in the Medline database.

RESULTS

In patients with a high risk constellation-e.g., chromosome 7 anomalies, complex aberrations, or FLT3-length mutations-there is an indication for SCT in first remission. The balanced translocations t(15;17) and t(8;21), and the inversion inv(16) are prognostically favorable and are thus not considered an indication for SCT in first remission. The establishment of indications for stem cell transplantation also depends on the residual leukemic cell burden (minimal residual disease, MRD) as determined by the quantitative polymerase chain reaction or by flow cytometry, as well as an insufficient response to induction chemotherapy. Reduced-dose conditioning, a new technique that lessens acute toxicity, has been found to be associated with a 30% to over 50% two-year survival rate when used in the treatment of chemotherapeutically unresponsive or relapsing AML.

DISCUSSION

The indications for allogeneic SCT in AML should be further refined by more investigation in large studies.

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.

Allogeneic stem cell transplantation for myelodysplastic syndrome

Although it is only used to treat a minority of patients with myelodysplastic syndromes, stem cell transplantation (SCT) is the only proven curative treatment for this condition. Because MDS occurs in a population of older adults with significant comorbidities, reduced-intensity conditioning (RIC) regimens have been particularly important in extending safe SCT to the large MDS population over the age of 60 years. Extension of the unrelated donor pool together with the introduction of umbilical cord blood transplants in adults has extended the number of patients with suitable donors. Nevertheless overall mortality from SCT is greater than 50% because of relapse and non-relapse mortality (NRM). New developments to improve outcome include the tailoring of the transplant approach to the individual based on age and comorbidity, and the use of pretransplant chemotherapy to reduce disease bulk prior to transplant, as well as the introduction of post-transplant immunotherapy (pre-emptive donor lymphocyte infusions) and chemotherapy to prevent relapse. Further improvements in transplant outcome await better ways to reconstitute immunity and amplify the graft-versus-leukemia (GVL) effect without causing graft-versus-host disease (GVHD), as well as further extension of the donor pool and exploration of risk-adapted regimens for the population of MDS in their seventh to eighth decade.

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.

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.

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.

Viewpoint: What is the role of allogeneic haematopoietic cell transplantation in the era of reduced-intensity conditioning--is there still an upper age limit? A focus on myeloid neoplasia

Allogeneic haematopoietic cell transplantation (HCT) is the most effective curative therapy in acute myeloid leukaemia (AML) and myelodysplastic syndromes (MDS). Incidence of AML and MDS increases with age, peaking in the seventh decade. Despite improved Ara-C and anthracyclin-based chemotherapy regimens, the prognosis of AML in patients beyond 60 years of age is dismal. The introduction of peripheral blood-derived stem cell grafts into allogeneic HCT and the known anti-leukaemic effect of donor lymphocyte infusions paved the way for reduced-intensity conditioning (RIC) allogeneic stem-cell transplantation, which makes transplant in advanced age possible and significantly reduces transplant-related organ toxicity and mortality. The success of RIC HCT relies on the alloreactivity of the donor immune system and the graft-versus-leukaemia effect. We try to answer the following questions in this paper: who should receive RIC HCT? when and how should the transplant be performed? is there an upper age limit and what is the future of RIC HCT?

The Graft Content of Donor T Cells Expressing γδTCR+ and CD4+foxp3+ Predicts the Risk of Acute Graft versus Host Disease after Transplantation of Allogeneic Peripheral Blood Stem Cells from Unrelated Donors

PURPOSE

Recently, high numbers of regulatory T cells within the stem cell graft were described to be associated with less graft-versus-host disease (GVHD) after related peripheral blood stem cell transplantation (PBSCT). Studies in mice also suggest a distinct role of gamma delta TCR(+) T cells in mediating GVHD. Therefore, the aim of this study was to define the yet-unknown role of regulatory and gamma delta TCR(+) T cells in human PBSCT from unrelated donors.

EXPERIMENTAL DESIGN

The frequency of both T-cell subsets within the graft was analyzed in 63 patients receiving unrelated allogeneic PBSCT. The respective amounts were quantified by flow cytometry and PCR and further correlated with clinical outcome.

RESULTS

The grafts contained a median of 11.2 x 10(6)/kg CD4(+)foxp3(+) and 9.8 x 10(6)/kg gamma delta TCR(+) T cells, respectively. Patients receiving more CD4(+)foxp3(+) cells had a lower cumulative incidence of acute GVHD II-IV (44% versus 65%, P=0.03). Interestingly, in patients who received higher concentrations of donor gamma delta TCR(+) T cells, acute GVHD II-IV was more frequent (66% versus 40%, P=0.02). In multivariate analysis, only the graft concentration of gamma delta TCR(+) T cells (P=0.002) and a positive cytomegalovirus status of the recipient (P = 0.03) were significantly associated with the occurrence of acute GVHD II-IV.

CONCLUSION

Graft composition of T-cell subsets seems to affect the outcome of patients receiving allogeneic PBSCT from unrelated donors. Therefore, selective manipulation or add-back of particular subsets might be a promising strategy to reduce the incidence of GVHD.

Controversies in treatment of AML: case-based discussion

Treatment of acute myeloid leukemia (AML) in older adults remains a tremendous challenge. Standard approaches to treatment have resulted in progression-free survival in only a small minority of patients with AML over the age of 60. Elucidation of the molecular genetic events that contribute to the pathogenesis of AML in older patients are providing insights into mechanisms of resistance. This knowledge is also providing new opportunities to begin to refine and direct novel therapies for these heterogeneous diseases. In this case-based review, prognostic factors for treatment outcome in older adults will be covered along with discussion of a risk-based approach to potential therapeutic options, ranging from palliative care to novel therapies and reduced-intensity allogenic transplant.