Disease burden may identify patients more likely to benefit from second allogeneic hematopoietic stem cell transplantation to treat relapsed acute myelogenous leukemia

CLAG combined with total body irradiation as intensive conditioning chemotherapy prior to allogeneic hematopoietic stem cell transplantation in patients with refractory or relapsed acute myeloid leukemia

Refractory or relapsed acute myeloid leukemia (R/R AML) remains the major challenge of AML treatment. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only valid option to achieve cure, but the prognosis is still dismal. We conducted a retrospective analysis for the feasibility of CLAG regimens (cladribine, cytarabine, and granulocyte colony-stimulating factor) combined with total body irradiation (TBI) as new intensive conditioning chemotherapy prior to HSCT in R/R AML. A total of 70 patients, including 21 primary refractory and 49 relapsed AML, were analyzed. Forty-nine (70%) patients had extramedullary diseases, and 54 (77%) patients received haploidentical transplantation. Except for one who died before white blood cell engraftment, all of the 69 evaluable patients achieved measurable residual disease (MRD) negative complete remission. The 3-year overall survival (OS) and relapse-free survival (RFS) rates were 46.0% (95% confidence interval [CI], 33.5-57.7%) and 38.5% (95%CI, 26.8-50.0%). The 1-year cumulative incidences of relapse and non-relapse mortality (NRM) were 38.6% (95%CI, 27.3-49.3%) and 11.6% (95%CI: 5.4-20.3%), respectively. The presence of chronic graft-versus-host disease (cGVHD) showed a trend to be associated with a lower risk of relapse (P = 0.054) and extramedullary diseases with a higher risk of NRM (P = 0.074). Multivariate analyses identified low leukemia burden pre-HSCT (defined as bone marrow blasts ≤ 50%) and cGVHD as independent factors associated with favorable OS and RFS. In conclusion, intensive conditioning with CLAG regimens plus TBI may be an effective and well-tolerated choice for R/R AML patients undergoing allo-HSCT.

Late relapse after hematopoietic stem cell transplantation for acute leukemia: a retrospective study by SFGM-TC

Late relapse (LR) after allogeneic hematopoietic stem cell transplantation (AHSCT) for acute leukemia is a rare event (nearly 4.5%) and raises the questions of prognosis and outcome after salvage therapy. We performed a retrospective multicentric study between January 1, 2010, and December 31, 2016, using data from the French national retrospective register ProMISe provided by the SFGM-TC (French Society for Bone Marrow Transplantation and Cellular Therapy). We included patients presenting with LR, defined as a relapse occurring at least 2 years after AHSCT. We used the Cox model to identify prognosis factors associated with LR. During the study period, a total of 7582 AHSCTs were performed in 29 centers, and 33.8% of patients relapsed. Among them, 319 (12.4%) were considered to have LR, representing an incidence of 4.2% for the entire cohort. The full dataset was available for 290 patients, including 250 (86.2%) with acute myeloid leukemia and 40 (13.8%) with acute lymphoid leukemia. The median interval from AHSCT to LR was 38.2 months (interquartile range [IQR], 29.2 to 49.7 months), and 27.2% of the patients had extramedullary involvement at LR (17.2% exclusively and 10% associated with medullary involvement). One-third of the patients had persistent full donor chimerism at LR. Median overall survival (OS) after LR was 19.9 months (IQR, 5.6 to 46.4 months). The most common salvage therapy was induction regimen (55.5%), with complete remission (CR) obtained in 50.7% of cases. Ninety-four patients (38.5%) underwent a second AHSCT, with a median OS of 20.4 months (IQR, 7.1 to 49.1 months). Nonrelapse mortality after second AHSCT was 18.2%. The Cox model identified the following factors as associated with delay of LR: disease status not in first CR at first HSCT (odds ratio [OR], 1.31; 95% confidence interval [CI], 1.04 to 1.64; P = .02) and the use of post-transplantation cyclophosphamide (OR, 2.23; 95% CI, 1.21 to 4.14; P = .01). Chronic GVHD appeared to be a protective factor (OR, .64; 95% CI, .42 to .96; P = .04). The prognosis of LR is better than in early relapse, with a median OS after LR of 19.9 months. Salvage therapy associated with a second AHSCT improves outcome and is feasible, without creating excess toxicity.

Haploidentical versus Double-Cord Blood Stem Cells as a Second Transplantation for Relapsed Acute Myeloid Leukemia

There are limited data on second stem cell transplantation (SCT2) outcomes with alternative donors for relapsed AML after the first stem cell transplantation (SCT1). We analyzed the outcomes of 52 adult AML patients who received SCT2 from haploidentical donors (HIT, N = 32) and double-cord blood (dCBT, N = 20) between 2008 and 2021. The HIT group received T-cell-replete peripheral blood stem cells after reduced-toxicity conditioning with anti-thymocyte globulin (ATG), while the dCBT group received myeloablative conditioning. For a median follow-up of 64.9 months, the HIT group, compared to the dCBT group, had earlier engraftment, superior 2-year overall survival (OS), disease-free survival (DFS), and non-relapse mortality (NRM) with similar relapse. Multivariate analysis demonstrated that HIT was significantly associated with better OS, DFS, and lower NRM than dCBT. Both longer remission duration after SCT1 and complete remission at SCT2 were significantly associated with a lower relapse rate. In addition, bone marrow WT1 measurable residual disease (MRD) positivity was significantly associated with inferior OS and higher relapse. This study suggests that T-cell-replete HIT with ATG-based GVHD prophylaxis may be preferred over dCBT as SCT2 for relapsed AML and that WT1-MRD negativity may be warranted for better SCT2 outcomes.

[Safety of rabbit anti-human thymocyte immunoglobulin in second allogeneic hematopoietic stem cell transplantation for patients with hematological diseases]

Objective: To look into the security of a second allogeneic hematopoietic stem cell transplantation (allo-HSCT) using rabbit anti-human thymocyte immunoglobulin (rATG) . Methods: Twenty-seven patients who used rATG in the first and second allo-HSCT at the Institute of Hematology, Peking University were enrolled in the study. Experienced toxicities associated with the conditioning protocol within 10 days (-5 d to +3 d) following the beginning of the rATG application, including fever, diarrhea, arrhythmia, reduced blood pressure, liver damage, seizures, and other problems. Results: The overall incidence of conditioning regimen early adverse reactions during the first transplantation and the second allo-HSCT conditioning regimen was 96.3% and 77.8% (P=0.043) . Fever rates were 81.5% and 63.0% (P=0.129) , diarrhea rates were 59.3% and 25.9% (P=0.013) , liver damage rates were 22.2% and 25.9% (P=0.75) , and the rates of other events (cardiac arrhythmia, low blood pressure, and epilepsy) were 3.7% and 18.5% (P=0.083) . Adverse reactions that occurred during both the first and second course of rATG applications have been improved with symptomatic treatment, and no treatment interruptions occurred. Conclusion: Reusing rATG in a second transplant was risk-free and did not result in higher early toxicities.

A phase 1 trial utilizing TMI with fludarabine-melphalan in patients with hematologic malignancies undergoing second allo-SCT

Relapse after allogeneic stem cell transplantation (allo-SCT) remains the primary cause of treatment failure. A second SCT can result in long-term survival in a subset of patients, but the relapse rate remains high. We conducted a single-center, phase 1, modified 3 + 3 dose-escalation study of the feasibility of combining intensity-modulated total marrow irradiation (IM-TMI) with fludarabine and melphalan for conditioning. Between December 2015 and May 2020, 21 patients with relapsed hematologic disease undergoing second or greater allo-SCT were treated with IM-TMI doses of 6 Gy, 9 Gy, or 12 Gy. Dose-limiting toxicity was defined as a grade 3 or higher treatment-related adverse event; mucositis was the primary dose-limiting toxicity. The median times to neutrophil and platelet engraftment were 10 and 18 days, respectively. The 1-year cumulative incidence of graft-versus-host disease was 65% (95% confidence interval CI, 38-83). The nonrelapse mortality at 2 years was 17% (95% CI, 4-39). Cumulative incidence of relapse at 2 years was 35% (95% CI, 13-58). Two-year progression-free survival and overall survival were 48% and 50%. We conclude that combining IM-TMI with fludarabine-melphalan is feasible. We recommend 12 Gy of IM-TMI with fludarabine-melphalan for second SCT, although 9 Gy may be used for older or underweight patients.

Long-term follow-up of patients with poor-risk acute leukemia treated on a phase 2 trial undergoing intensified conditioning regimen prior to allogeneic hematopoietic cell transplantation

Patients with acute leukemia who undergo allogenic hematopoietic cell transplantation with active disease have high rates of relapse and poor overall survival (OS) post-transplant compared to patients undergoing HCT in remission. Here, we report the long-term outcomes in 32 patients who received a high-intensity conditioning regimen comprising fractionated total body irradiation (FTBI; 1200 cGy) with pharmacokinetic (PK) dosing of intravenous Busulfan (IV BU) targeted to first dose area under curve (AUC) of 700-900 µM/min and etoposide (30 mg/kg) in a prospective phase 2 clinical trial. The median age of the patients at the time of HCT was 37 years (range: 18-50) presenting with high-risk (n = 6) and relapsed/refractory(r/r) acute leukemias (n = 26). All but one patient underwent HCT using peripheral blood stem cells from matched sibling donors. At a median follow-up of 17.3 years (range 14.4-19.0), 11 patients remained alive. The disease-free survival and OS at 15 years was 34% (versus 40% at 5-years post-HCT). The 15-year cumulative incidence of relapse was 26% and non-relapse mortality (NRM) was 38% (95% CI: 21-54%) and the cumulative incidence of chronic GVHD at 15 years was 33% using a prophylactic regimen of cyclosporine A and mycophenolate mofetil. The most common life-threatening late effects were secondary malignancies, metabolic, or cardiac complications with a cumulative incidence of 6.6%, 6.6%, and 13.3%, respectively. No unusual late effects or patterns of relapse were noted on longer followed on patients treated with intensified myeloablative condition regimen. Results from this study supports continued development of intensive conditioning regimens in patients with r/r acute leukemias to improve leukemia free (LFS) and OS in this high-risk population.

Outcomes of Second Allogeneic Hematopoietic Cell Transplantation for Patients With Acute Myeloid Leukemia

Relapse after allogeneic hematopoietic cell transplantation (HCT) leads to poor survival in patients with acute myeloid leukemia (AML). A second HCT (HCT2) may achieve durable remission. To determine the outcomes of patients who received an HCT2 for relapsed AML and to evaluate the predictors of overall survival (OS) and progression-free survival (PFS). We retrospectively reviewed medical records of adult patients who underwent an HCT2 for relapsed AML at our institution during 2000 to 2019. Ninety-one patients were identified with a median age of 44 years (range 18-73) at HCT2. Donor types were HLA-identical sibling (n = 37 [41%]), HLA-matched-unrelated (n = 34 [37%]), haploidentical (n = 19 [21%]), and cord blood (n=1 [1%]). Donors were different at HCT2 in 53% of patients. The majority of patients received reduced intensity conditioning (n = 71 [78%]) and were in remission (n = 56 [61%]) at HCT2. The median remission duration after HCT1 was 8.4 months (range 1-70) and the median time between transplants was 14 months (range 3-73). The median follow-up of surviving patients after HCT2 was 66 months (range 2-171), with 32% alive at time of analysis. The most common cause of death was disease recurrence (n = 45 [73%]). At 2 years, the rates of OS, PFS, progression, and nonrelapse mortality were 36%, 27%, 42%, and 18%, respectively. The development of chronic graft-versus-host disease (GVHD) after first HCT and HCT comorbidity index (HCT-CI) ≥2 at HCT2 were associated with inferior PFS and OS after HCT2. A second HCT is feasible in selected patients with AML who have relapsed after HCT1. Long-term survival benefit is possible in patients without chronic GVHD after HCT1 and HCT-CI <2 at HCT2.

Prognostic factors for survival in children who relapsed after allogeneic hematopoietic stem cell transplantation for acute leukemia

BACKGROUND

Post-transplant relapse has a dismal prognosis in children with acute leukemia undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Data on risk factors, treatment options, and outcomes are limited.

PROCEDURE

In this retrospective multicenter study in which a questionnaire was sent to all pediatric transplant centers reporting relapse after allo-HSCT for a cohort of 938 children with acute leukemia, we analyzed 255 children with relapse of acute leukemia after their first allo-HSCT.

RESULTS

The median interval from transplantation to relapse was 180 days, and the median follow-up from relapse to the last follow-up was 1844 days. The 3-year overall survival (OS) rate was 12.0%. The main cause of death was disease progression or subsequent relapse (82.6%). The majority of children received salvage treatment with curative intent without a second HSCT (67.8%), 22.0% of children underwent a second allo-HSCT, and 10.2% received palliative therapy. Isolated extramedullary relapse (hazard ratio (HR): 0.607, P = .011) and relapse earlier than 365 days post-transplantation (HR: 2.101, P < .001 for 0-180 days; HR: 1.522, P = .041 for 181-365 days) were found in multivariate analysis to be significant prognostic factors for outcome. The type of salvage therapy in chemosensitive relapse was identified as a significant prognostic factor for OS.

CONCLUSION

A salvage approach with curative intent may be considered for patients with post-transplant relapse, even if they relapse in the first year post-transplantation. For sustainable remission, a second allo-HSCT may be recommended for patients who achieve complete remission after reinduction treatment.

Second unmanipulated allogeneic transplantation could be used as a salvage option for patients with relapsed acute leukemia post-chemotherapy plus modified donor lymphocyte infusion

Relapse is the main problem after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The outcome of a second allo-HSCT (HSCT2) for relapse post-HSCT has shown promising results in some previous studies. However, little is known about the efficacy of HSCT2 in patients with relapsed/refractory acute leukemia (AL) post-chemotherapy plus modified donor lymphocyte infusion (post-Chemo + m-DLI) after the first allo-HSCT (HSCT1). Therefore, we retrospectively analyzed the efficacy of HSCT2 in 28 patients with relapsed/refractory AL post-Chemo + m-DLI in our center. With a median follow-up of 918 (457-1732) days, 26 patients (92.9%) achieved complete remission, and 2 patients exhibited persistent disease. The probabilities of overall survival (OS) and disease-free survival (DFS) 1 year after HSCT2 were 25.0% and 21.4%, respectively. The cumulative incidences of nonrelapse mortality on day 100 and at 1 year post-HSCT2 were 7.1% ± 4.9% and 25.0% ± 8.4%. The cumulative incidences of relapse were 50.0% ± 9.8% and 53.5% ± 9.9% at 1 and 2 years post-HSCT2, respectively. Risk stratification prior to HSCT1 and percentage of blasts before HSCT2 were independent risk factors for OS post-HSCT2, and relapse within 6 months post-HSCT1 was an independent risk factor for DFS and relapse post-HSCT2. Our findings suggest that HSCT2 could be a salvage option for patients with relapsed AL post-Chemo + m-DLI.

Outcomes of pediatric patients who relapse after first HCT for acute leukemia or MDS

Disease relapse remains a major cause of treatment failure in patients receiving allogeneic hematopoietic cell transplantation (alloHCT) for high-risk acute leukemias or myelodysplastic syndromes (MDS). Comprehensive data on outcomes after post-transplant relapse are lacking, especially in pediatric patients. Our objective was to assess the impact of various transplant-, patient-, and disease-related variables on survival and outcomes in patients who relapse after alloHCT. We describe our institutional experience with 221 pediatric patients who experienced disease relapse after their first alloHCT for acute leukemias or MDS between 1990 and 2018. In a multivariable model, being in first complete remission at first alloHCT, longer duration of remission after alloHCT, experiencing GVHD and receiving a transplant in a more recent time period were significantly associated with a higher likelihood of receiving a second alloHCT after post-transplant relapse. Of these variables, only longer interval from alloHCT to relapse, receiving a second alloHCT or DLI, and receiving a transplant in a more recent time period were associated with improved overall survival. Our data support pursuing second alloHCT for patients who have experienced relapse after their first transplant, as that remains the only salvage modality with a reasonable chance of inducing long-term remission.

Second allogeneic hematopoietic stem cell transplantation in patients with acute leukemia relapsed after allogeneic hematopoietic stem cell transplantation

The prognosis of patients with acute leukemia relapsed after allogeneic hematopoietic stem cell transplantation (HSCT) is dismal. We aimed to evaluate the outcomes and prognostic factors of the second HSCT (HSCT2) in acute leukemia patients relapsed after the first HSCT (HSCT1). We analyzed 80 patients who received HSCT2 for relapsed acute leukemia in two Korean institutes. All but four patients received HSCT2 from a donor other than matched sibling donor: an unrelated donor (URD) in 30 and a familial haploidentical donor (FHD) in 46. Forty-four patients (55.0%) were in complete remission (CR) or CR with incomplete count recovery (CRi) at HSCT2, and the median time from HSCT1 to relapse was 9 months. The 2-year overall survival (OS) and event-free survival (EFS) were 21.0% and 17.5%, respectively. The outcomes were similar between URD and FHD. Multivariate analysis demonstrated that disease status (active disease vs. CR/CRi) at HSCT2 and remission duration after HSCT1 were independent prognostic factors for OS and EFS after HSCT2. HSCT2 from URD or FHD was feasible in patients with acute leukemia relapsed after allogeneic HSCT. Also, our study confirmed two critical prognostic factors; disease status at HSCT2 and remission duration after HSCT1.

Haploidentical transplants for patients with relapse after the first allograft

Relapse after allogeneic hematopoietic stem-cell transplantation (AHSCT) is associated with very poor outcomes. A second transplant offers the possibility of long-term disease control. We analyzed outcomes with haploidentical donors for second allograft at our institution. All consecutive patients with hematological malignancies (N = 29) who relapsed after AHSCT and underwent a haploidentical transplant (haploSCT) as second transplant between February 2009 and October 2018 were included. Median age was 36 years (interquartile range (IQR) 24-60); 83% of patients had high/very high disease risk index; 61% of AML/MDS patients had high-risk cytogenetics; and only 24% were in complete remission at transplant. With a median follow-up of 46.9 months, the 3-year relapse, non-relapse mortality (NRM), progression-free survival (PFS) and overall survival (OS) were 30%, 39%, 31% and 40%, respectively. In multivariable analysis (MVA), comorbidity index (HCT-CI) and detectable donor-specific anti-HLA antibodies (DSA) prior to second transplant were significantly associated with worse outcomes. Patients with HCT-CI <3 and without DSA had 3-year PFS and OS of 53% and 60.3%, respectively. Our findings suggest that haploSCT as second AHSCT is feasible and potentially curative. Lower HCT-CI and no DSA were associated with lower NRM and improved survival. Haploidentical grafts might be a preferred donor source for second AHSCT as these are high-risk patients who frequently need to proceed urgently to transplant.

Cytogenetics and Blast Count Determine Transplant Outcomes in Patients with Active Acute Myeloid Leukemia

Acute myeloid leukemia (AML) patients not in remission and beyond first or second complete remission are considered allogeneic stem cell transplant (SCT) candidates. We present 361 patients who underwent SCT from matched related or unrelated donors between 2005 and 2013. The purpose was to identify a subgroup of patients with active disease at the time of transplant that benefit. Cox proportional hazards regression analysis was used for univariate and multivariate analyses to predict overall survival (OS). Variables considered were age, sex, SWOG cytogenetic risk group, bone marrow (BM) and peripheral blood (PB) blast percentage, regimen intensity, and type of AML. At a median of 26 months after transplantation, OS, progression-free survival (PFS), non-relapse mortality, and relapse rates were 26, 24, 23, and 48%, respectively. In a univariate analysis, risk cytogenetics (p < 0.001) and BM blasts >4% (p = 0.006) or any blasts in PB (p < 0.001) indicated worse OS. In a multivariate analysis, patients with <5% BM blasts or absence of circulating blasts and good or intermediate risk cytogenetics had significantly superior OS (46%), PFS (44%), and disease progression at 3 years. Based on these findings, patients not in remission with good or intermediate risk cytogenetics and low blast counts should be considered for SCT.

Optimal Delivery of Follow-Up Care After Allogeneic Hematopoietic Stem-Cell Transplant: Improving Patient Outcomes with a Multidisciplinary Approach

The increasing indications for allogeneic stem-cell transplant in patients with hematologic malignancies and non-malignant diseases combined with improved clinical outcomes have contributed to increase the number of long-term survivors. However, survivors are at increased risk of developing a unique set of complications and late effects, besides graft-versus-host disease and disease relapse. In this setting, the management capacity of a single health-care provider can easily be overwhelmed. Thus, to provide appropriate survivorship care, a multidisciplinary approach for the long-term follow-up is essential. This review aims at summarizing the most relevant information that a health-care provider should know to establish a follow-up care plan, in the light of individual exposures and risk factors, that includes all organ systems and considers the psychological burden of these patients.

What is the role of a second allogeneic hematopoietic cell transplant in relapsed acute myeloid leukemia?

Relapsed acute myeloid leukemia (AML) after an allogeneic hematopoietic cell transplant (allo-HCT) entails a poor prognosis. Treating these cases is challenging due to lack of effective therapies and, in some cases, poor performance status and/or presence of graft-versus-host disease (GVHD), among others. No randomized controlled trial (RCT) has ever been conducted comparing a second allo-HCT against other treatments. Existing data are mainly from observational studies or registries. Success of a second allo-HCT is dependent on appropriately selecting patients who might achieve best outcomes with reasonable non-relapse mortality (NRM) risk. Several factors are associated with worse outcomes, namely a shorter time from first allo-HCT to relapse or to the second allo-HCT, and AML not being in complete hematologic remission (CR). Patients relapsing earlier than 6 months or having active/persistent disease should be enrolled in clinical trials. Limitations of the published literature include retrospective small size studies, a heterogeneous population, and absence of information on somatic mutations, among others. Future studies assessing the role of a second allo-HCT should evaluate the impact of IDH1, IDH2, or others on outcomes; and the feasibility and efficacy of targeted therapies in the pre-, peri-, or post-second allo-HCT setting.

Outcomes following second allogeneic stem cell transplant for disease relapse after T cell depleted transplant correlate with remission status and remission duration after the first transplant

Background

Second allogeneic hematopoietic stem cell transplant (HCT) remains as an option for disease relapse after initial HCT.

Methods

We analyzed retrospectively the outcomes of 65 consecutive patients who underwent a second HCT for disease relapse at the University of Chicago. Univariate and multivariate analysis were conducted, and a scoring system was generated to select the patients who would benefit second HCT.

Results

All except four patients received T cell depleted (TCD) first HCT. The majority of patients had AML (n = 47) and high risk MDS (n = 5). The median age at second HCT was 45 years (11–73). 13 patients (20%) achieved CR before second HCT. 98% (n = 64) and 72% (n = 47) patients achieved neutrophil and platelet engraftment at a median interval of 10 and 18 days, respectively, following the second HCT. With a median follow up of 23 (5.5–140) months for survivors after second HCT, the estimated 2 years PFS was 17.5% and the 2 years OS was 22.6%. The day 100 cumulative incidence of non-relapse mortality rate was 23.6%, and the cumulative incidence of aGVHD and cGVHD were 16.9% and 7.7% respectively at 1 year after second HCT. In univariate analysis, patients with remission duration after first HCT of > 12 months and those in CR before second HCT had significantly better PFS and OS. A scoring system using disease status before second HCT (CR = 0 vs. non-CR = 1), and remission duration after first HCT (< 6 = 2, 6–12 = 1 and > 12 months = 0) was generated as an approach to classify patients into different risk categories in the purpose to provide guidance to the transplant physician to inform the outcomes to potential patients undergoing 2nd HCT. A score of < 2 (n = 26) identified a group with PFS and OS of 31.6% and 36.2% at 2 years after second HCT.

Conclusion

In conclusion, second HCT is a viable option for disease relapse after TCD HCT for patients entering second HCT in remission and/or remission duration > 12 months after first HCT with acceptable rates of GVHD and donor engraftment.

Prevention and treatment of relapse after stem cell transplantation by cellular therapies

Despite recent advances in reducing therapy-related mortality after allogeneic stem cell transplantation (alloSCT) relapse remains the major cause of treatment failure and little progress has been achieved in the last decades. At the 3rd International Workshop on Biology, Prevention, and Treatment of Relapse held in Hamburg/Germany in November 2016 international experts presented and discussed recent developments in the field. Here, the potential of cellular therapies including unspecific and specific T cells, genetically modified T cells, CAR-T cells, NK-cells, and second allografting in prevention and treatment of relapse after alloSCT are summarized.

Prognostic Prediction Model for Second Allogeneic Stem-Cell Transplantation in Patients With Relapsed Acute Myeloid Leukemia: Single-Center Report

PURPOSE

To identify factors affecting survival outcomes and to develop a prognostic model for second allogeneic stem-cell transplantation (allo-SCT2) for relapsed acute myeloid leukemia (AML) after the first autologous or allogeneic stem-cell transplantation.

PATIENTS AND METHODS

Seventy-eight consecutive adult AML patients who received allo-SCT2 were analyzed in this retrospective study.

RESULTS

The 4-year overall survival (OS) rate was 28.7%. In multivariate analysis, poor cytogenetic risk at diagnosis, circulating blast ≥ 20% at relapse, duration from first transplantation to relapse < 9 months, and failure to achieve morphologic complete remission after allo-SCT2 were factors associated with poor OS. A prognostic model was developed with the following score system: intermediate and poor cytogenetic risk at diagnosis (0.5 and 1 point), peripheral blast ≥ 20% at relapse (1 point), duration from the first transplantation to relapse < 9 months (1 point), and failure to achieve morphologic complete remission after allo-SCT2 (1 point). The model identified 2 subgroups according to the 4-year OS rate: 51.3% in the low-risk group (score < 2) and 2.8% in the high-risk group (score ≥ 2) (P < .001).

CONCLUSION

This prognostic model might be useful to make an appropriate decision for allo-SCT2 in relapsed AML after the first autologous or allogeneic stem-cell transplantation.

Outcome of myeloablative allogeneic peripheral blood hematopoietic stem cell transplantation for refractory/relapsed AML patients in NR status

To further find effective method to improve the long term survival of refractory or relapsed acute myeloid leukemia (AML) patients, we retrospectively analyzed the outcomes of myeloablative hematopoietic stem cell transplantation (HSCT) for 133 consecutive patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) therapy related AML(t-AML) in not remission status. The overall 3-year OS and DFS were 40.9% and 35.6% respectively. The variables associated with improved long term DFS were a bone marrow blast cell count less than 20% and an intensified conditioning regimen. In addition, the t-AML group had higher rates of relapse and III-IV acute GVHD than the primary AML group. The unrelated donor group had similar OS and DFS with sibling groups. Our study suggested that decreasing bone marrow blast cell counts before HSCT and strengthening the conditioning regimen may improve long-term DFS for refractory/relapsed AML patients, and unrelated donor group can get similar effect when compared to the sibling group.

Second allogeneic transplantation for relapse of malignant disease: retrospective analysis of outcome and predictive factors by the EBMT

In patients treated with allogeneic stem cell transplantation (SCT) for malignant disease who suffer from a relapse after the transplantation, the role of second allogeneic SCT is often uncertain. In a retrospective analysis, 2632 second allogeneic transplantations carried out for a relapse after the first transplantation were analyzed to define indications and identify predictive factors. Fifteen percent of the patients remained relapse-free until 5 years after the second SCT. Patients with CML had a better survival than patients with other diseases. In a multivariate analysis, factors associated with better survival were low disease burden, longer remission duration after the first transplantation, longer interval between the transplantations, younger age, absence of grade II-IV acute GvHD or chronic GvHD after the first transplantation, and later year of transplantation. The European Society for Blood and Marrow Transplantation risk score predicted the outcome. Using the same donor as in the first transplantation vs another donor had no predictive value for survival. Sibling donor was a favorable predictive factor. In conclusion, second allogeneic SCT offers a reasonable option especially for young patients with a long remission after the first transplantation and a low disease burden. The present findings do not support the usefulness of changing the donor for the second transplantation.

Second allogeneic transplantation using unrelated cord blood for relapsed hematological malignancies after allogeneic transplantation

The efficacy of second allogeneic stem cell transplantation (SCT2) using cord blood (CB) for patients with relapsed hematological malignancies after initial allogeneic stem cell transplantation (SCT1) is unknown. We analyzed the results of SCT2 using single-unit unrelated CB in 34 adult patients with relapsed hematological malignancies after SCT1 in our institution. The patients had acute myeloid leukemia (n = 23), acute lymphoblastic leukemia (n = 7), chronic myelogenous leukemia (n = 2), and myelodysplastic syndrome (n = 2). The cumulative incidence of neutrophil and platelet engraftment was 81.6% at 30 days and 68.5% at 100 days, respectively. With a median follow-up of 40 months, the probability of overall survival at 3 years was 29.0%. The cumulative incidence of relapse and transplant-related mortality at 3 years were 60.7% and 27.2%, respectively. The use of CB could offer the opportunity to receive SCT2 for patients who experienced disease relapse after SCT1 without HLA-identical related or unrelated donors.

Treatment strategies in patients with AML or high-risk myelodysplastic syndrome relapsed after Allo-SCT

Non-relapse mortality after Allo-SCT has significantly decreased over the last years. Nevertheless, relapse remains a major cause for post SCT mortality in patients with AML and high-risk myelodysplastic syndrome (MDS). In this retrospective single-center analysis, we have analyzed the treatment outcomes of 108 patients with AML or MDS, who relapsed after Allo-SCT. Seventy of these patients (65%) were treated with salvage therapies containing chemotherapy alone, allogeneic cell-based treatment or the combination of both. Thirty-eight patients (35%) received palliative treatment. Median OS after diagnosis of relapse was 130 days. Compared with patients who received chemotherapy alone, response to salvage therapy was significantly improved in patients treated with a combination of chemo- and allogeneic cell-based therapy (CR rate 57% vs 13%, P=0.002). Among risk factors concerning pretreatment characteristics, disease status before first Allo-SCT, and details of transplantation, only the time interval from Allo-SCT to relapse was an independent predictor of response to salvage therapy and OS. These data confirmed that time to relapse after transplantation is an important prognostic factor. Up to now, only patients eligible for treatment regimens containing allogeneic cell-based interventions achieved relevant response rates.

Long-term survival and late effects among one-year survivors of second allogeneic hematopoietic cell transplantation for relapsed acute leukemia and myelodysplastic syndromes

We analyzed the outcomes of patients who survived disease-free for 1 year or more after a second allogeneic hematopoietic cell transplantation (HCT) for relapsed acute leukemia or myelodysplastic syndromes between 1980 and 2009. A total of 1285 patients received a second allogeneic transplant after disease relapse; among these, 325 were relapse free at 1 year after the second HCT. The median time from first to second HCT was 17 and 24 months for children and adults, respectively. A myeloablative preparative regimen was used in the second transplantation in 62% of children and 45% of adult patients. The overall 10-year conditional survival rates after second transplantation in this cohort of patients who had survived disease-free for at least 1 year was 55% in children and 39% in adults. Relapse was the leading cause of mortality (77% and 54% of deaths in children and adults, respectively). In multivariate analyses, only disease status before second HCT was significantly associated with higher risk for overall mortality (hazard ratio, 1.71 for patients with disease not in complete remission before second HCT, P < .01). Chronic graft-versus-host disease (GVHD) developed in 43% and 75% of children and adults after second transplantation. Chronic GVHD was the leading cause of nonrelapse mortality, followed by organ failure and infection. The cumulative incidence of developing at least 1 of the studied late effects within 10 years after second HCT was 63% in children and 55% in adults. The most frequent late effects in children were growth disturbance (10-year cumulative incidence, 22%) and cataracts (20%); in adults they were cataracts (20%) and avascular necrosis (13%). Among patients with acute leukemia and myelodysplastic syndromes who receive a second allogeneic HCT for relapse and survive disease free for at least 1 year, many can be expected to survive long term. However, they continue to be at risk for relapse and nonrelapse morbidity and mortality. Novel approaches are needed to minimize relapse risk and long-term transplantation morbidity in this population.

Haploidentical stem cell transplantation for acute leukemia patients who experienced early relapse within one year after the first transplantation

To assess the safety and efficacy of allogeneic stem cell transplantation from haploidentical related donors (haplo-SCT) as 2nd transplantation for patients with early relapsed disease, we retrospectively evaluated 7 consecutive patients (median age, 42 years; range, 29-63 years) who experienced relapse within 1 year of the 1st transplantation and received haplo-SCT as a 2nd transplantation. Among the 7 patients who received haplo-SCT, 2 who were in morphologically complete remission (CR) at transplantation were conditioned with a reduced-intensity regimen, and the 5 non-CR patients were conditioned with a myeloablative regimen. Both conditioning regimens included antithymocyte globulin. Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus and methylprednisolone. Sustained neutrophil engraftment was achieved in all 7 patients. One patient developed severe acute GVHD. Notably, only 1 patient experienced relapse, and each patient achieved longer CR duration than after the 1st transplantation. Three of the 7 patients died from treatment-related causes: acute GVHD, post-transplantation lymphoproliferative disorder, and bacterial pneumonia. At the time of analysis, the 2-year overall survival rate of these 7 patients was 42.9%. This suggests that use of haploidentical related donors is a viable alternative for 2nd transplantation and should be confirmed in larger cohorts.

Conditioning regimens in acute myeloid leukemia

Current intensive consolidation chemotherapy for patients with acute myeloid leukemia (AML) produces median remission duration of 12-18 months, with less than 30% of patients surviving 5 years free of disease. Post-remission therapy is necessary to prevent relapse in most patients with AML; therefore, the aim of post-remission treatment is to eradicate the minimal residual disease. Nevertheless, the optimal form of treatment is still under debate. The choice among the possible approaches (intensive chemotherapy, autologous or allogeneic hematopoietic stem cell transplantation) relies on two main factors: the expected risk of relapse, as determined by biological features, and expected morbidity and mortality associated with a specific option. In this review, we focus on the different preparative regimens before autologous and allogeneic hematopoietic stem cell transplantation in patients with AML, stressing the importance of an adequate conditioning regimen as a mandatory element of a successful AML therapy, in both the allogeneic and the autologous transplant setting.

Second haematopoietic SCT using HLA-haploidentical donors in patients with relapse of acute leukaemia after a first allogeneic transplantation

Haploidentical haematopoietic SCT (HSCT) using T-cell-replete grafts and post-transplant high-dose CY has found increasing acceptance. Our purpose was to evaluate the feasibility and outcome of this strategy as second HSCT incorporating donor change for acute leukaemia relapse after a first allogeneic transplantation. The courses of 20 consecutive adults (median age 37 years, 12 male) with AML (n=14), ALL (n=5) and acute bi-phenotypic leukaemia (n=1) were analysed retrospectively. Conditioning consisted of fludarabine, CY and either melphalan or TBI or tresosulfan+/-etoposide. Engraftment was achieved in 17 (85%), and a second remission was induced in 15 patients (75%) on day +30. The rate of grade II-IV acute GvHD was 35%, while chronic GvHD occurred in five patients. Most commonly observed grade III-IV toxicities were mucositis (30%), hyperbilirubinemia (20%), elevation of transaminases (20%) and creatinine (20%), while invasive fungal infection affected 30%. One-year non-relapse mortality (NRM) was 36%. At a median follow-up of 17 months, estimated 1-year OS was 45%, and 1-year relapse-free survival was 33%. This strategy was feasible and allowed for successful engraftment with a moderate rate of toxicity. Early outcome and NRM are at least comparable with results after a second HSCT from HLA-matched donors without donor change at HSCT2.

Immunotherapy following relapse of acute leukaemia after T-cell-replete allogeneic peripheral blood progenitor cell transplantation: importance of new onset chronic graft-versus-host disease

INTRODUCTION

To further define the relative impact of immunotherapy and subsequent development of graft-versus-host disease (GVHD) on survival in patients with relapsed acute leukaemia postallogeneic hematopoietic stem cell transplant (SCT), we performed a single-centre retrospective analysis of 32 actively treated patients between 2003 and 2011.

METHODS

A total of 13 patients were identified who were treated actively with cessation of immunosuppression ± Fludarabine, Cytarabine, G-CSF (FLAG) induction, but no donor leucocyte infusion (DLI) (non-DLI group) and 19 patients received the same step-wise therapy plus G-CSF mobilized DLI (G-DLI group).

RESULTS

Groups were not statistically different with regards to baseline characteristics; however, the G-DLI group contained more sibling donors as opposed to unrelated donors than the non-DLI group. With a median follow-up of 47 months, the median overall survival (OS) of the non-DLI and G-DLI groups was not statistically different (8 months vs. 9 months, respectively, P = 0.5). Survival at 3 years was <10% in both groups. Univariate analysis identified response to FLAG, and new onset chronic GVHD as the only factors associated with improved OS.

CONCLUSION

Second donor stem cell infusions are unwarranted in the treatment of relapse after allogeneic SCT and therapeutic strategies should focus on cytoreduction followed by immune modulation with the aim of invoking chronic GVHD.

Feasibility of clofarabine cytoreduction followed by haploidentical hematopoietic stem cell transplantation in patients with relapsed or refractory advanced acute leukemia

Clofarabine is a novel purine nucleoside analogue with immunosuppressive and anti-leukemic activity in acute lymphoblastic and myeloid leukemia (AML, ALL). This retrospective study was performed to evaluate the feasibility and anti-leukemic activity of a sequential therapy using clofarabine for cytoreduction followed by conditioning for haploidentical hematopoietic stem cell transplantation (HSCT) in patients with non-remission acute leukemia. Patients received clofarabine (5 × 30 mg/m² IV) followed by a T cell replete haploidentical transplantation for AML (n = 15) or ALL (n = 3). Conditioning consisted of fludarabine, cyclophosphamide plus either melphalan, total body irradiation or treosulfan/etoposide. High-dose cyclophosphamide was administered for post-grafting immunosuppression. Neutrophil engraftment was achieved in 83 % and complete remission in 78% at day +30. The rate of acute graft versus host disease (GvHD) grade II-IV was 22%, while chronic GvHD occured in five patients (28%). Non-relapse mortality (NRM) after 1 year was 23%. At a median follow-up of 19 months, estimated overall survival and relapse-free survival at 1 year from haploidentical HSCT were 56 and 39%, respectively. Non-hematological regimen-related grade III-IV toxicity was observed in ten patients (56%) and included most commonly transient elevation of liver enzymes (44%), mucositis (40%), and skin reactions including hand-foot syndrome (17%), creatinine elevation (17%), and nausea/vomiting (17%). The concept of a sequential therapy using clofarabine for cytoreduction followed by haploidentical HSCT proved to be feasible and allows successful engraftment, while providing an acceptable toxicity profile and anti-leukemic efficacy in patients with advanced acute leukemia. NRM and rate of GvHD were comparable to results after HSCT from HLA-matched donors.

Second allograft for hematologic relapse of acute leukemia after first allogeneic stem-cell transplantation from related and unrelated donors: the role of donor change

PURPOSE

To evaluate the role of a second allogeneic hematopoietic stem-cell transplantation (HSCT2) given for relapsed acute leukemia (AL) after related or unrelated first hematopoietic stem-cell transplantation (HSCT1) and to analyze the role of donor change for HSCT2 in both settings.

PATIENTS AND METHODS

We performed a retrospective registry study on 179 HSCT2s given for relapse after HSCT1 from matched related donors (n = 75) or unrelated donors (n = 104), using identical or alternative donors for HSCT2. Separate analyses were performed according to donor at HSCT1.

RESULTS

Independent of donor, 74% of patients achieved complete remission after HSCT2, and half of these patients experienced relapse again. Overall survival (OS) at 2 years was 25% ± 4% (39% ± 7% after related HSCT2; 19% ± 4% after unrelated HSCT2). Long-term survivors were observed even after two unrelated HSCT2s. Multivariate analysis for OS from HSCT2 confirmed established risk factors (remission duration after HSCT1: hazard ratio [HR], 2.37; 95% CI, 1.61 to 3.46; P < .001; stage at HSCT2: HR, 0.53; 95% CI, 0.34 to 0.83; P = .006). Outcome of HSCT2 was better after related HSCT1 than after unrelated HSCT1 (2-year OS: 37% ± 6% v 16% ± 4%, respectively; HR, 0.68; 95% CI, 0.47 to 0.98; P = .042, multivariate Cox regression). After both related and unrelated HSCT1, selecting a new donor for HSCT2 did not result in a relevant improvement in OS compared with HSCT2 from the original donor; however, donor change was not detrimental either.

CONCLUSION

After relapse from allogeneic HSCT1, HSCT2 can induce 2-year OS in approximately 25% of patients. Unrelated HSCT2 is feasible after related and unrelated HSCT1. Donor change for HSCT2 is a valid option. However, a clear advantage in terms of OS could not be demonstrated.

Expanded indications for allogeneic stem cell transplantation in patients with myeloid malignancies

PURPOSE OF REVIEW

Hematopoietic stem cell transplantation (SCT) can be curative for myeloid malignancies such as acute myeloid leukemia (AML). Advancements in human leukocyte antigen (HLA) typing and supportive care have improved the risk-benefit ratio for SCT, expanding its indications.

RECENT FINDINGS

Allogeneic SCT is an established treatment for AML with intermediate-risk and high-risk cytogenetics in first complete remission (CR1), from matched related donors (MRDs). Similar survival benefits are seen for AML in CR1 with unfavorable cytogenetics using matched unrelated donors (URDs). Molecular characterization has delineated patients with AML at higher risk with normal cytogenetics [e.g., FLT3-internal tandem duplication (ITD)+]. The outcomes of allogeneic SCT are comparable in patients with therapy-related or de-novo AML when adjusted for disease status and cytogenetics. In patients lacking a MRD, the majority will have a suitable alternative using an URD, umbilical cord blood, or haploidentical-related donors; outcomes are either comparable or relatively acceptable compared to a matched sibling donor. Comorbidity indices aid in identifying elderly and debilitated patients who may benefit from SCT; the application of SCT has been further increased by reduced-intensity conditioning regimens.

SUMMARY

Allogeneic SCT may be extended to almost all patients with AML, and integration of toxicity and relapse risks will determine the best approach for allogeneic SCT in the future.

Second allogeneic hematopoietic SCT for relapsed ALL in children

A second SCT is generally accepted as the only potentially curative approach for ALL patients that relapse after SCT, but the role of second SCT for pediatric ALL is not fully understood. We performed a retrospective analysis of 171 pediatric patients who received a second allo-SCT for relapsed ALL after allo-SCT. OS at 2 years was 29.4 ± 3.7%, the cumulative incidence of relapse was 44.1 ± 4.0% and non-relapse mortality was 18.8 ± 3.5%. Relapse occurred faster after the second SCT than after the first SCT (117 days vs 164 days, P=0.04). Younger age (9 years or less), late relapse (180 days or more after first SCT), CR at the second SCT, and myeloablative conditioning were found to be related to longer survival. Neither acute GVHD nor the type of donor influenced the outcome of second SCT. Multivariate analysis showed that younger age and late relapse were associated with better outcomes. Our analysis suggests that second SCT for relapsed pediatric ALL is an appropriate treatment option for patients that have achieved CR, which is associated with late relapse after the first SCT.

Clinical options after failure of allogeneic hematopoietic stem cell transplantation in patients with hematologic malignancies

Disease recurrence is the single most common cause of death after allogeneic or autologous hematopoietic stem cell transplantation (HSCT). Disease status and chemosensitivity at the time of transplantation, as well as the development of graft-versus-host disease (GVHD), are factors known to influence the risk of relapse post-HSCT. Both acute and chronic GVHD have been associated with decreased relapse rates; however, owing to toxicity, overall survival is not consistently improved in these patients. Furthermore, there is a transient period of immunodeficiency after HSCT, which may permit residual malignant cells to proliferate early in the post-transplant course, before the donor immune system can establish a graft-versus-tumor response. Patients who fail an initial HSCT have an extremely poor outcome; therefore, maneuvers to prevent, identify and treat recurrent disease as early as possible in these situations are necessary. Strategies to distinguish graft-versus-tumor from GVHD, to enhance both general and disease-specific immune reconstitution after transplantation, and to increase donor-mediated anti-host immune reactions are being investigated in clinical trials. Single agent nontoxic post-HSCT chemotherapy, cellular therapies and second allogeneic HSCT using reduced intensity regimens are among the modalities under investigation.

Relapse after allogeneic stem cell transplantation

Since allogeneic stem cell transplantation (SCT) represents an intensive curative treatment for high-risk malignancies, its failure to prevent relapse leaves few options for successful salvage treatment. While many patients have a high early mortality from relapse, some respond and have sustained remissions, and a minority has a second chance of cure with appropriate therapy. The prognosis for relapsed hematological malignancies after SCT depends on four factors: the time elapsed from SCT to relapse (with relapses occurring within 6 months having the worst prognosis), the disease type (with chronic leukemias and some lymphomas having a second possibility of cure with further treatment), the disease burden and site of relapse (with better treatment success if disease is treated early), and the conditions of the first transplant (with superior outcome for patients where there is an opportunity to increase either the alloimmune effect, the specificity of the antileukemia effect with targeted agents or the intensity of the conditioning in a second transplant). These features direct treatments toward either modified second transplants, chemotherapy, targeted antileukemia therapy, immunotherapy or palliative care.

Allogeneic hematopoietic cell transplantation for adults with acute myeloid leukemia: myths, controversies, and unknowns

Progress in the last decade has improved the understanding of leukemia biology. Molecular markers in combinations with cytogenetics have improved the risk stratification of acute myeloid leukemia (AML) and informed decision-making. In parallel, several important advances in the transplant field, such as better supportive care, improved transplant technology, increased availability of alternative donors, and reduced-intensity conditioning have improved the safety as well as access of allogeneic hematopoietic cell transplantation (HCT) for a larger number of patients. In this review, the positioning of HCT in the management of patients with AML is evaluated in view of changing risk/benefit ratios associated with both conventional treatments and transplantation, and some of the controversies are addressed in light of emerging data. Increasing data demonstrate outcomes of alternative donor transplantation approaching HLA-identical sibling donors in high-risk AML supporting the inclusion of alternative donors in trials of prospective studies evaluating post remission strategies for high-risk AML. The use of reduced-intensity conditioning has expanded the eligibility of HCT to older patients with AML, and outcome data are encouraging. Continued study of HCT versus alternative therapies is required to optimize patients' outcomes in AML.

Hematopoietic stem-cell transplantation for acute leukemia in relapse or primary induction failure

PURPOSE

Patients with acute leukemia refractory to induction or reinduction chemotherapy have poor prognoses if they do not undergo hematopoietic stem-cell transplantation (HSCT). However, HSCT when a patient is not in complete remission (CR) is of uncertain benefit. We hypothesized that pretransplantation variables may define subgroups that have a better prognosis.

PATIENTS AND METHODS

Overall, 2,255 patients who underwent transplantation for acute leukemia in relapse or with primary induction failure after myeloablative conditioning regimen between 1995 and 2004 were reported to the Center for International Blood and Marrow Transplant Research. The median follow-up of survivors was 61 months. We performed multivariate analysis of pretransplantation variables and developed a predictive scoring system for survival.

RESULTS

The 3-year overall survival (OS) rates were 19% for acute myeloid leukemia (AML) and 16% for acute lymphoblastic leukemia (ALL). For AML, five adverse pretransplantation variables significantly influenced survival: first CR duration less than 6 months, circulating blasts, donor other than HLA-identical sibling, Karnofsky or Lansky score less than 90, and poor-risk cytogenetics. For ALL, survival was worse with the following: first refractory or second or greater relapse, > or = 25% marrow blasts, cytomegalovirus-seropositive donor, and age of 10 years or older. Patients with AML who had a predictive score of 0 had 42% OS at 3 years, whereas OS was 6% for a score > or = 3. Patients with ALL who had a score of 0 or 1 had 46% 3-year OS but only 10% OS rate for a score > or = 3.

CONCLUSION

Pretransplantation variables delineate subgroups with different outcomes. HSCT during relapse can achieve long-term survival in selected patients with acute leukemia.

Outcome of 93 patients with relapse or progression following allogeneic hematopoietic cell transplantation

Relapse/progression after allogeneic hematopoietic cell transplantation (allo-HCT) remains the major cause of treatment failure. In this study, the subsequent clinical outcome was overviewed in 292 patients with leukemia/myelodysplastic syndrome who received allo-HCT. Among them, 93 (32%) showed relapse/progression. Cohort 1 was chosen to receive no interventions with curative intent (n = 25). Cohort 2 received reinduction chemotherapy and/or donor lymphocyte infusion (n = 48), and Cohort 3 underwent a second allo-HCT (n = 20). Sixty-three patients received reinduction chemotherapy, and 27 (43%) achieved subsequent complete remission (CR). The incidence of nonrelapse mortality (NRM) was similar among the three cohorts (4, 15, and 5%). The 1-year overall survival (OS) after relapse was significantly better in patients with a second HCT (58%) than in others (14%, Cohorts 1 and 2; P <.001). However, the 2-year OS did not differ between the two groups, which suggests that it is difficult to maintain CR after the second HCT. Multivariate analysis showed that reinduction chemotherapy, CR after intervention, second HCT, and longer time to post-transplant relapse were associated with improved survival. In conclusion, for patients with relapse after allo-HCT, successful reinduction chemotherapy and a second HCT may be effective for prolonging survival without excessive NRM. However, effective measures to prevent disease progression after a second HCT clearly need to be developed.

Management of relapse after allo-SCT for AML and the role of second transplantation

Relapse after allo-SCT for AML carries very poor prognosis. Second allo-SCT, although curative, is not an appropriate treatment option for a large number of relapsing patients (only 2-20% patients receive a second allo-SCT), and efforts to increase the number of patients who may benefit from a second allo-SCT are ongoing. In addition, understanding the varied biological processes that are operative in disease relapse has encouraged the development of novel therapies, and could be beneficial to patients who are currently managed conservatively with supportive care for relapsed disease. Incorporating novel combinations of drugs with immunomodulation, although theoretically attractive, should be tested in the setting of clinical trials. In this review, we discuss the currently available approaches for relapsed AML after allo-SCT.