Classifying cytogenetics in patients with acute myelogenous leukemia in complete remission undergoing allogeneic transplantation: a Center for International Blood and Marrow Transplant Research study

Azacitidine and gemtuzumab ozogamicin as post-transplant maintenance therapy for high-risk hematologic malignancies

Disease recurrence remains the principal cause of treatment failure after allogeneic hematopoietic stem cell transplantation. Post-transplant maintenance therapy with azacitidine (AZA) is promising to prevent relapse but the outcomes are unsatisfactory in patients at high risk of recurrence. Herein, we evaluated the outcome in patients who received AZA and gemtuzumab ozogamicin (GO), anti-CD33 antibody-calicheamicin conjugate, as post-transplant maintenance therapy. Twenty-eight patients with high-risk hematologic malignancies harboring CD33-positive leukemic blasts received the maintenance therapy. AZA (30 mg/m2) was administered for 7 days, followed by GO (3 mg/m2) on day 8. The maximum number of cycles was 4. At transplant, 21 patients (75.0%) had active disease. Their 2-year overall survival, disease-free survival, relapse, and non-relapse mortality rates were 53.6%, 39.3%, 50.0%, and 10.7%, respectively. Of these patients, those with minimal residual disease at the start of maintenance therapy (n = 9) had a higher recurrence rate (66.7% vs. 42.1% at 2 years, P = 0.069) and shorter disease-free survival (11.1% vs. 52.6% at 2 years, P = 0.003). Post-transplant maintenance therapy with AZA and GO was generally tolerable but more than half of the patients eventually relapsed. Further improvements are needed to prevent relapse after transplantation in patients with high-risk hematologic malignancies.

Cytogenetic abnormalities predict survival after allogeneic hematopoietic stem cell transplantation for pediatric acute myeloid leukemia: a PDWP/EBMT study

Poor-risk (PR) cytogenetic/molecular abnormalities generally direct pediatric patients with acute myeloid leukemia (AML) to allogeneic hematopoietic stem cell transplant (HSCT). We assessed the predictive value of cytogenetic risk classification at diagnosis with respect to post-HSCT outcomes in pediatric patients. Patients younger than 18 years at the time of their first allogeneic HSCT for AML in CR1 between 2005 and 2022 who were reported to the European Society for Blood and Marrow Transplantation registry were subgrouped into four categories. Of the 845 pediatric patients included in this study, 36% had an 11q23 abnormality, 24% had monosomy 7/del7q or monosomy 5/del5q, 24% had a complex or monosomal karyotype, and 16% had other PR cytogenetic abnormalities. In a multivariable model, 11q23 (hazard ratio [HR] = 0.66, P = 0.03) and other PR cytogenetic abnormalities (HR = 0.55, P = 0.02) were associated with significantly better overall survival when compared with monosomy 7/del7q or monosomy 5/del5q. Patients with other PR cytogenetic abnormalities had a lower risk of disease relapse after HSCT (HR = 0.49, P = 0.01) and, hence, better leukemia-free survival (HR = 0.55, P = 0.01). Therefore, we conclude that PR cytogenetic abnormalities at diagnosis predict overall survival after HSCT for AML in pediatric patients.

Pretransplant Desensitization of Donor-Specific Anti-HLA Antibodies with Plasmapheresis and Immunoglobulin Produces Equivalent Outcomes to Patients with No Donor Specific Antibodies in Haploidentical Hematopoietic Cell Transplant

In patients requiring haploidentical hematopoietic cell transplant (haplo-HCT), the presence of donor specific anti-HLA antibodies (DSAs) is associated with high rates of primary graft failure and poor overall survival (OS). There is limited data regarding the effect of desensitization. Adult patients undergoing haplo-HCT at Washington University School of Medicine from 2009-2021 were identified. Patients were divided into three cohorts: no DSA, untreated DSA or treated DSA. DSA testing was performed. Desensitization therapy using plasmapheresis and IVIg (immunoglobulin) was performed. We retrospectively identified 304 patients for study inclusion. 14 of 30 patients with DSAs underwent desensitization. By day +2, 57% of patients cleared all DSAs. OS was expectedly worse in patients with untreated DSAs. There were similar results between treated DSA and patients without DSA (OS median: control: 352 days vs. treated: 1331 days vs. untreated: 137 days, p = 0.02). RFS was also significantly different between the groups however with similar RFS in treated DSA and control groups (RFS median: control: 248 vs. treated: 322 v. untreated: 119, p = 0.03). Desensitization before haplo-HCT produces similar outcomes to patients without DSAs. While the optimal desensitization protocol has not been established, all patients received a backbone of plasmapheresis and immunoglobulin.

Prognostic impact of complex and/or monosomal karyotypes in post-transplant poor cytogenetic acute myeloid leukaemia: A quantitative approach

To evaluate the prognostic impact of complex karyotype (CK) and/or monosomal karyotype (MK) in combination with various clinical factors on allogeneic stem cell transplantation (HSCT) outcomes of patients with acute myeloid leukaemia (AML), we analysed the registry database of adult AML patients who underwent allogeneic HSCT between 2000 and 2019 in Japan. Among 16 094 patients, those with poor cytogenetic risk (N = 3345) showed poor overall survival (OS) after HSCT (25.3% at 5 years). Multivariate analyses revealed that CK and/or MK (hazard ratio [HR], 1.31 for CK without MK; 1.27 for MK without CK; and 1.73 for both), age at HSCT ≥50 years (HR, 1.58), male sex (HR, 1.40), performance status ≥2 (HR, 1.89), HCT-CI score ≥3 (HR, 1.23), non-remission status at HSCT (HR, 2.49), and time from diagnosis to HSCT ≥3 months (HR, 1.24) independently reduced post-HSCT OS among patients with poor cytogenetic risk AML. A risk scoring system based on the multivariate analysis successfully stratified patients into five distinct groups for OS. This study confirms the negative effects of CK and MK on post-HSCT outcomes, and offers a powerful risk scoring system for predicting prognoses after HSCT among AML patients with unfavourable cytogenetics.

Feasibility, safety, and efficacy of early prophylactic donor lymphocyte infusion after T cell-depleted allogeneic stem cell transplantation in acute leukemia patients

Prophylactic donor lymphocyte infusion (DLI) starting at 6 months after T cell-depleted allogeneic stem cell transplantation (TCD-alloSCT) can introduce a graft-versus-leukemia (GvL) effects with low risk of severe graft-versus-host-disease (GvHD). We established a policy to apply low-dose early DLI at 3 months after alloSCT to prevent early relapse. This study analyzes this strategy retrospectively. Of 220 consecutive acute leukemia patients undergoing TCD-alloSCT, 83 were prospectively classified to have a high relapse risk and 43 were scheduled for early DLI. 95% of these patients received freshly harvested DLI within 2 weeks of the planned date. In patients transplanted with reduced intensity conditioning and an unrelated donor, we found an increased cumulative incidence of GvHD between 3 and 6 months after TCD-alloSCT for patients receiving DLI at 3 months compared to patients who did not receive this DLI (0.42 (95%Confidence Interval (95% CI): 0.14-0.70) vs 0). Treatment success was defined as being alive without relapse or need for systemic immunosuppressive GvHD treatment. The five-year treatment success in patients with acute lymphatic leukemia was comparable between high- and non-high-risk disease (0.55 (95% CI: 0.42-0.74) and 0.59 (95% CI: 0.42-0.84)). It remained lower in high-risk acute myeloid leukemia (AML) (0.29 (95% CI: 0.18-0.46)) than in non-high-risk AML (0.47 (95% CI: 0.42-0.84)) due to an increased relapse rate despite early DLI.

Allogeneic stem cell transplantation in the treatment of acute myeloid leukemia: An overview of obstacles and opportunities

As an important treatment for acute myeloid leukemia, allogeneic hematopoietic stem cell transplantation (allo-HSCT) plays an important role in reducing relapse and improving long-term survival. With rapid advancements in basic research in molecular biology and immunology and with deepening understanding of the biological characteristics of hematopoietic stem cells, allo-HSCT has been widely applied in clinical practice. During allo-HSCT, preconditioning, the donor, and the source of stem cells can be tailored to the patient’s conditions, greatly broadening the indications for HSCT, with clear survival benefits. However, the risks associated with allo-HSCT remain high, i.e. hematopoietic reconstitution failure, delayed immune reconstitution, graft-versus-host disease, and post-transplant relapse, which are bottlenecks for further improvements in allo-HSCT efficacy and have become hot topics in the field of HSCT. Other bottlenecks recognized in the current treatment of individuals diagnosed with acute myeloid leukemia and subjected to allo-HSCT include the selection of the most appropriate conditioning regimen and post-transplantation management. In this paper, we reviewed the progress of relevant research regarding these aspects.

How I treat with maintenance therapy after allogeneic HCT

Disease relapse is the leading cause of failure for patients receiving allogeneic hematopoietic cell transplantation (allo-HCT). Maintenance therapy administered after allo-HCT is a promising strategy to reduce the incidence of relapse and enhance the curative potential of allo-HCT. Research investigations and clinical applications of this approach have greatly increased in recent years, with an expanding number of available therapeutic agents to introduce in the posttransplant setting. However, many questions and challenges remain regarding the feasibility and clinical impact of maintenance. In this article, we present four common case scenarios addressing select available therapeutic agents as a framework to review published data and ongoing studies and describe our current standard practice in the rapidly evolving field of maintenance therapy after allo-HCT.

Outcomes after allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia patients with der(1;7)(q10;p10)

The prognosis of acute myeloid leukemia (AML) patients with der(1;7)(q10;p10) who underwent allogeneic hematopoietic stem cell transplantation (allo-SCT) is unclear due to its rarity. We retrospectively analyzed 151 AML patients with der(1;7)(q10;p10) and compared the findings with those of 853 AML patients with monosomy 7 or chromosome 7q deletion (-7/del(7q)) using Japanese nationwide registry data. The der(1;7)(q10;p10) group showed significantly better transplant outcomes than the -7/del(7q) group. In the multivariate analysis of the der(1;7)(q10;p10) group, additional chromosomal abnormalities and a poor performance status significantly influenced the survival. In conclusion, allo-SCT is a feasible treatment option for AML patients with der(1;7)(q10;p10).

Pediatric acute myeloid leukemia patients with KMT2A rearrangements: a single-center retrospective study

PURPOSE

Pediatric acute myeloid leukemia (AML) with KMT2A rearrangements has a very different prognosis. Poor outcomes cannot be avoided even after hematopoietic stem cell transplantation. In order to investigate the prognosis and efficacy, we conducted a retrospective analysis.

PATIENTS AND METHODS

We retrospectively analyzed a total of 32 children with KMT2A rearrangements AML treated in our hospital between January 2015 and February 2021.

RESULTS

The proportion of patients with KMT2A-rearranged in the medium-risk group of overall survival (OS) and event-free survival (EFS) was 100%. No differences in OS, EFS and cumulative incidence of relapse (CIR) were detected between the haploidentical hematopoietic stem cell transplantation (haplo-HSCT) and full matched HSCT (P = 0.289, P = 0.303, P = 0.303). Acute graft-versus-host disease (aGVHD) was often detected in the haplo-HSCT cohort, while full matched HSCT had no obvious aGVHD, assessed as≤1 grade (P < 0.05). Patients in the medium-risk pediatric group could acquire 100% OS and EFS only after chemotherapy. There was no significant difference in OS, EFS and CIR between full matched HSCT and haploidentical transplantation in pediatric AML with KMT2A rearrangements, but full matched HSCT seemed to have a lower death rate. The severity of aGVHD in the full matched HSCT was less than that in the haploidentical transplantation group.

CONCLUSION

The primary choice of donor can be HLA-matched sibling donors or matched unrelated donors for children with AML with KMT2A rearrangements, and the secondary choice can be haploid donors.

Impact of the MRD status in AML patients undergoing allogeneic stem cell transplantation in first vs second remission

Allogeneic hematopoietic stem cell transplantation (HSCT) offers the best chance for relapse-free survival to most acute myeloid leukemia (AML) patients. It might be performed in complete remission or delayed until after first relapse due to relevant treatment-related morbidity and mortality. The measurable residual disease (MRD) status at HSCT adds refined prognostic information to the assigned European LeukemiaNet (ELN) 2017 genetic risk at diagnosis. We analyzed 580 AML patients receiving allogeneic HSCT in either first (79%) or second (21%) remission. Although - due to common treatment strategies - some adverse risk characteristics, such as monosomal or complex karyotypes were less frequent in patients transplanted in second remission, they had worse outcomes compared to patients transplanted in first remission. The MRD status at HSCT was an independent prognostic factor irrespective of the number of remission at HSCT. Noteworthy, MRDpos patients transplanted in first remission and MRDneg patients transplanted in second remission had similar outcomes. In the clinically highly relevant group of ELN2017 intermediate risk individuals, the MRD status provided the highest prognostic value with very dismal outcomes of patients transplanted in MRDpos second remission. The adverse outcomes of MRDpos patients and individuals transplanted in second remission should be considered when planning consolidation treatment, to avert an allogeneic HSCT in MRDpos second remission when possible.

Adding venetoclax to fludarabine/busulfan RIC transplant for high-risk MDS and AML is feasible, safe, and active

Adding the selective BCL-2 inhibitor venetoclax to reduced-intensity conditioning chemotherapy (fludarabine and busulfan [FluBu2]) may enhance antileukemic cytotoxicity and thereby reduce the risk of posttransplant relapse. This phase 1 study investigated the recommended phase 2 dose (RP2D) of venetoclax, a BCL-2 selective inhibitor, when added to FluBu2 in adult patients with high-risk acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), and MDS/myeloproliferative neoplasms (MPN) undergoing transplant. Patients received dose-escalated venetoclax (200-400 mg daily starting day -8 for 6-7 doses) in combination with fludarabine 30 mg/m2 per day for 4 doses and busulfan 0.8 mg/kg twice daily for 8 doses on day -5 to day -2 (FluBu2). Transplant related-toxicity was evaluated from the first venetoclax dose on day -8 to day 28. Twenty-two patients were treated. At study entry, 5 patients with MDS and MDS/MPN had 5% to 10% marrow blasts, and 18 (82%) of 22 had a persistent detectable mutation. Grade 3 adverse events included mucositis, diarrhea, and liver transaminitis (n = 3 each). Neutrophil/platelet recovery and acute/chronic graft-versus-host-disease rates were similar to those of standard FluBu2. No dose-limiting toxicities were observed. The RP2D of venetoclax was 400 mg daily for 7 doses. With a median follow-up of 14.7 months (range, 8.6-24.8 months), median overall survival was not reached, and progression-free survival was 12.2 months (95% confidence interval, 6.0-not estimable). In patients with high-risk AML, MDS, and MDS/MPN, adding venetoclax to FluBu2 was feasible and safe. To further address relapse risk, assessment of maintenance therapy after venetoclax plus FluBu2 transplant is ongoing. This study was registered at clinicaltrials.gov as #NCT03613532.

Type 1 interferon to prevent leukemia relapse after allogeneic transplantation

Augmenting early GVL response by prophylactic type 1 IFN may reduce the rates of leukemic relapse after HCT in very high–risk AML.

Reciprocal toxicities, including acute GVHD and nonrelapse mortality, were not increased after type 1 IFN treatment.

A potent graft-versus-leukemia (GVL) response is crucial in preventing relapse, the major impediment to successful allogeneic hematopoietic cell transplantation (HCT). In preclinical studies, type 1 interferon (IFN-α) enhanced cross-presentation of leukemia-specific antigens by CD8α dendritic cells (DCs) and amplified GVL. This observation was translated into a proof-of-concept phase 1/2 clinical trial with long-acting IFN-α (pegylated IFN-α [pegIFNα]) in patients undergoing HCT for high-risk acute myeloid leukemia (AML). Patients with treatment-resistant AML not in remission or those with poor-risk leukemia were administered 4 dosages of pegIFNα every 14 days beginning at day −1 before HCT. Dose selection was established by adaptive design that continuously assessed the probability of dose-limiting toxicities throughout the trial. Efficacy was evaluated by determining the 6-month incidence of relapse at the maximum tolerated dose (MTD). Thirty-six patients (median age, 60 years) received pegIFNα treatment. Grade 3 or greater severe adverse events occurred in 25% of patients, establishing 180 μg as the MTD. In phase 2, the incidence of relapse was 39% at 6 months, which was sustained through 1-year post-HCT. The incidence of transplant-related mortality was 13%, and severe grade III-IV acute graft-versus-host disease (GVHD) occurred in 11%. Paired blood samples from donors and recipients after HCT revealed elevated levels of type 1 IFN with cellular response, the persistence of cross-presenting DCs, and circulating leukemia antigen-specific T cells. These data suggest that prophylactic administration of pegIFNα is feasible in the peri-HCT period. In high-risk AML, increased toxicity was not observed with preliminary evidence for reduction in leukemia relapse after HCT. This trial was registered at www.clinicaltrials.gov as #NCT02328755.

A phase II study of azacitidine in combination with granulocyte-macrophage colony-stimulating factor as maintenance treatment, after allogeneic blood or marrow transplantation in patients with poor-risk acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS)

Relapse is the most common cause of treatment failure following allogeneic blood or marrow transplantation (alloBMT) for AML or MDS. Post-transplant maintenance therapies may prevent relapse. We conducted a phase II trial combining azacitidine (AZA) with GM-CSF in non-relapsed, post-transplant patients with AML or MDS. Patients received escalating doses of AZA to a maximum of 75 mg/m² for 5 days per cycle for up to 12 cycles. GM-CSF was given on days 1-10 of each cycle. Eighteen patients were treated following non-myeloablative (17) and myeloablative (1) alloBMT for AML (61.1%), MDS (27.7%), or therapy-related myeloid neoplasm (11.1%). The majority of patients (72%) received their graft from an HLA-haploidentical donor. The treatment was well-tolerated with rare grade 3-4 hematologic toxicities. One patient suffered an exacerbation of GVHD. The 24-month relapse-free and overall survivals were 47 and 57%, respectively, with a median of 18.6 and 29 months.

Prognostic value of measurable residual disease at allogeneic transplantation for adults with core binding factor acute myeloid leukemia in complete remission

Pretransplant measurable residual disease (MRD) has been shown to be associated with relapse incidence following allogeneic hematopoietic cell transplantation (HCT) for acute myeloid leukemia (AML). However, it remains less clear whether pretransplant MRD status affects transplant outcomes in core binding factor AML (CBF-AML). We retrospectively evaluated the effect of pretransplant MRD, which was measured by a polymerase chain reaction of RUNX1-RUNX1T1 or CBFB-MYH11 fusion transcripts, on transplant outcomes for a cohort of 959 adult patients with t(8;21) or inv(16) AML treated by allogeneic HCT during complete remission (CR), between 2000 and 2018. Multivariate analysis showed the absence of pretransplant MRD was significantly associated with lower relapse (hazard ratio [HR], 0.46; P < 0.001), treatment failure (HR, 0.66; P = 0.004), and overall mortality (HR, 0.72; P = 0.037) among patients with t(8;21). However, pretransplant MRD negativity was not associated with relapse (HR, 0.73; P = 0.420), treatment failure (HR, 0.64; P = 0.063), or overall mortality (HR, 0.69; P = 0.149) among patients with inv(16). In subgroup analysis, pretransplant MRD status significantly affected relapse and LFS only in patients with t(8;21) undergoing allogeneic HCT during CR2. In conclusion, our data demonstrate the different prognostic values of pretransplant MRD for CBF-AML, highlighting the need to develop effective therapeutic strategies for such MRD-positive patients.

High lactate dehydrogenase at time of admission for allogeneic hematopoietic transplantation associates to poor survival in acute myeloid leukemia and non-Hodgkin lymphoma

Risk stratification is important for balancing potential risks and benefits of allogeneic hematopoietic stem cell transplantation (HSCT) for hematological malignancies. We retrospectively studied 1119 patients undergoing allogenic-HSCT in a single center for five hematological indications assessing the prognostic role of LDH at admission for survival (OS), progression-free survival (PFS), relapse incidence (RI), and nonrelapse mortality (NRM). In non-Hodgkin lymphoma (NHL) and acute myeloid leukemia (AML), higher than median LDH had an adverse effect on survival. The prognostic significance was strongest in AML, with higher LDH levels having lower 1-and 3-year survival 69.2% vs. 50.8%, P < 0.001 and 51.9% vs. 39.2%, P < 0.001, respectively, reduced 1-and 3-year PFS 62.4% vs. 42.1%, P < 0.001 48% vs. 35.2%, P < 0.001, respectively, higher cumulative incidence of 1-and 3-year NRM 11% vs. 17.3%, p = 0.01 and 15.7% vs. 19.6%, P = 0.04, and higher 1-and 3-year relapse incidence (RI) 26.7% vs. 40.7%, p < .0001 36.2% vs. 40.7%, respectively, P < 0.0001). In multivariate analysis LDH maintained significant prognostic capacity in OS, PFS and RI. These findings in AML, validated in an independent cohort, suggest that LDH is a readily available tool that could be integrated into transplant risk assessments to aid decision-making and identify high-risk patients who may benefit from post-transplant pharmacological or cellular strategies.

The evolving concept of indications for allogeneic hematopoietic cell transplantation during first complete remission of acute myeloid leukemia

The long-standing debate of whether patients with acute myeloid leukemia (AML) should proceed to allogeneic hematopoietic cell transplantation (HCT) during first complete remission (CR1) remains unsettled. Although allogeneic HCT during CR1 used to be recommended for those with intermediate or poor cytogenetics if they had a matched sibling donor, the concept of indications for allogeneic HCT during CR1 has been evolving by virtue of advances in understanding of the molecular pathogenesis of AML and innovations in transplantation practice attained over the last few decades. The incorporation of molecular profiles of leukemia has been shown to contribute to further refinements of risk classification that had previously relied mostly on cytogenetics, while the progress in transplantation procedures has made it possible to perform transplantations more safely even for patients without a matched sibling donor. These significant changes have underpinned the need to reappraise indications for allogeneic HCT during CR1 of AML. Improvements in clinical applications of genetic and measurable residual disease information as well as in transplantation technology are expected to further refine indications for allogeneic HCT during CR1, and thus promote an individualized approach for the treatment of AML.

Prognostic impact of the adverse molecular-genetic profile on long-term outcomes following allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia

The impact of adverse risk genetic profiles on outcomes in acute myeloid leukemia (AML) patients following allogeneic hematopoietic stem cell transplantation (HCT) has not been fully elucidated. Accordingly, we have profiled somatic mutations at diagnosis using next-generation sequencing (NGS) in 178 AML patients who received allogeneic HCT. NGS revealed 598 somatic mutations in 165/178 patients (92.7%). Frequently mutated genes include DNMT3A, TET2, NPM1, RUNX1, IDH2, and FLT3. Commonly detected cytogenetic profiles include normal karyotype, trisomy 8, monosomal karyotype (MK), deletion 5, complex karyotype (CK), and monosomy 7. In univariate analyses, TP53 mutation, MK, CK, and monosomy 7 were associated with decreased overall survival (OS), relapse-free survival (RFS), and a higher relapse incidence (RI). We defined adverse molecular-genetic profile as harboring at least one of the molecular/genetic abnormalities of TP53 mutation, MK, CK, monosomy 7, and deletion 5. The patients harboring adverse molecular-genetic profile (n = 30) showed a lower 2-year OS (24.9% vs. 57.9%; p = 0.003), RFS (23.7% vs. 57.9%; p = 0.002), and higher RI (47.2% and 17.2%; p = 0.001) after HCT when compared to patients without those lesions. Multivariate analysis confirmed adverse molecular-genetic profile as an independent prognostic factor, associated with decreased OS (HR 2.19), RFS (HR 2.23), and higher RI (HR 2.94).

Post-Transplant Maintenance Therapy for Patients with Acute Myeloid Leukemia: Current Approaches and the Need for More Trials

Relapse rates following allogeneic stem cell transplantation for acute myeloid leukemia remain unacceptably high and a major cause of death. Maintenance therapies post-transplant administered either to patients with impending relapse or at high risk of relapse could present a strategy to improve survival and overall outcomes. With the increasing use of molecular and genomic characterization of the disease, more novel therapies became available as maintenance strategies. These options were, however, hindered by excessive toxicities, mostly hematologic, especially with the use of myeloablative conditioning regimens. Several key questions have also emerged including the efficacy of these therapies, the duration of maintenance, as well as the potential modulation of the graft and the immune microenvironment. These issues are further complicated by the paucity of well-designed prospective randomized clinical trials evaluating these agents. Future directions in this field should include better risk stratification and patient selection based on assays of minimal residual disease, as well as the incorporation of novel targets and pathways of leukemogenesis. In this article, we highlight the current evidence behind the use of post-transplant maintenance therapy, the optimal patient and disease selection, as well as the challenges faced by these strategies in an area that remains quite controversial. We will focus on therapies targeting leukemia stem cells that directly or indirectly modulate the allografted immune microenvironment and augment the graft-versus-leukemia impact.

Myeloid sarcoma, chloroma, or extramedullary acute myeloid leukemia tumor: A tale of misnomers, controversy and the unresolved

The World Health Organization classification and definition of "myeloid sarcoma" is imprecise and misleading. A more accurate term is "extramedullary acute myeloid leukemia tumor (eAML)." The pathogenesis of eAML has been associated with aberrancy of cellular adhesion molecules, chemokine receptors/ligands and RAS-MAPK/ERK signaling. eAML can present with or without synchronous or metachronous intramedullary acute myeloid leukemia (AML) so a bone marrow evaluation is always recommended. Accurate diagnosis of eAML requires tissue biopsy. eAML confined to one or a few sites is frequently treated with local therapy such as radiotherapy. About 75-90% of patients with isolated eAML will develop metachronous intramedullary AML with a median latency period ranging from 4 to 12 months; thus, patients with isolated eAML may also be treated with systemic anti-leukemia therapy. eAML does not appear to have an independent prognostic impact; selection of post-remission therapy including allogeneic hematopoietic cell transplant (alloHCT) is typically guided by intramedullary disease risk. Management of isolated eAML should be individualized based on patient characteristics as well as eAML location and cytogenetic/molecular features. The role of PET/CT in eAML is also currently being elucidated. Improving outcomes of patients with eAML requires further knowledge of its etiology and mechanism(s) as well as therapeutic approaches beyond conventional chemotherapy, ideally in the context of controlled trials.

Myeloablative Conditioning for Allogeneic Transplantation Results in Superior Disease-Free Survival for Acute Myelogenous Leukemia and Myelodysplastic Syndromes with Low/Intermediate but not High Disease Risk Index: A Center for International Blood and Marrow Transplant Research Study

Compared with reduced-intensity conditioning (RIC), myeloablative conditioning (MAC) is generally associated with lower relapse risk after allogeneic hematopoietic cell transplantation (HCT) for acute myelogenous leukemia (AML) and myelodysplastic syndromes (MDS). However, disease-specific risk factors in AML/MDS can further inform when MAC and RIC may yield differential outcomes. We analyzed HCT outcomes stratified by the Disease Risk Index (DRI) in 4387 adults (age 40 to 65 years) to identify the impact of conditioning intensity. In the low/intermediate-risk DRI cohort, RIC was associated with lower nonrelapse mortality (NRM) (hazard ratio [HR], .74; 95% confidence interval [CI], .62 to .88; P < .001) but significantly greater relapse risk (HR, 1.54; 95% CI, 1.35 to 1.76; P < .001) and thus inferior disease-free survival (DFS) (HR, 1.19; 95% CI, 1.07 to 1.33; P = .001). In the high/very high-risk DRI cohort, RIC was associated with marginally lower NRM (HR, .83; 95% CI, .68 to 1.00; P = .051) and significantly higher relapse risk (HR, 1.23; 95% CI, 1.08 to 1.41; P = .002), leading to similar DFS using either RIC or MAC. These data support MAC over RIC as the preferred conditioning intensity for patients with AML/MDS with low/intermediate-risk DRI, but with a similar benefit as RIC in high/very high-risk DRI. Novel MAC regimens with less toxicity could benefit all patients, but more potent antineoplastic approaches are needed for the high/very-high risk DRI group.

The effect of donor type on outcomes in adults with acute myeloid leukemia after reduced-intensity hematopoietic peripheral blood cell transplant - a retrospective study

We retrospectively analyzed outcomes in patients with acute myeloid leukemia (AML) receiving reduced-intensity conditioning (RIC) hematopoietic stem cell transplants (HCT) from a peripheral blood (PB) source. We identified 46 haploidentical HCT (haplo), 59 matched unrelated donor HCT (MUD), and 40 matched related donor HCT (SIB) patients at a single institution. Haplo had improved overall survival (OS) when compared to MUD, HR 2.03 (P = 0.01) but not SIB, HR 1.17 (P = 0.61). There were no differences in relapse rates or treatment-related mortality (TRM). Haplo had higher rates of acute graft-versus-host disease (GVHD) grade II-IV at day 180 than MUD (44% vs. 25%, P = 0.03) and SIB (44% vs. 13% P < 0.01). Rates of acute GVHD III-IV and chronic GVHD were similar among the groups. Haplo had slower engraftment rates compared to MUD with neutrophil engraftment at 87% vs. 93%, (P < 0.01) and platelet engraftment at 59% vs. 86%, (P < 0.01) at 28 days. Although patients receiving haplo had higher acute GVHD II-IV and slower engraftment, they did not have increased TRM. These data may suggest that patients receiving haplo have improved OS compared to MUD for AML patients receiving RIC transplants. This should be confirmed using a larger cohort.

Monosomal karyotype affecting outcomes of allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia in first complete remission

OBJECTIVES

We evaluated the prognostic impact of MK on postremission outcomes of AML patients receiving allogeneic hematopoietic stem cell transplantation (HSCT) in the first complete remission (CR1).

METHODS

We retrospectively analyzed 465 adult patients with AML who had received HSCT in the first CR between 2000 and 2016.

RESULTS

In MK + AML, the median leukocyte count was significantly lower (P < .001) and no NPM1 mutation was found (P = .042). Multivariate analysis revealed that MK was the most powerful prognostic factors for OS (hazard ratio [HR], 2.6; P = .001), EFS (HR, 3.8; P < .001), and cumulative incidence of relapse (HR, 6.1; P < .001), compared to any other poor risk factors such as complex karyotype, FLT3-ITD mutations, old age, and higher leukocyte count. The adverse prognostic impact of MK tended to be more prominent in the younger age group (<40 years) (HR, 6.3, P < .001) than in the older age group (≥40 years) (HR, 3.4, P < .001).

CONCLUSION

Novel treatment modalities for MK + AML need to be investigated to reduce the risk of relapse after HSCT.

Predictive value of disease risk comorbidity index for overall survival after allogeneic hematopoietic transplantation

Allogeneic hematologic cell transplantation (alloHCT) is the only curative therapy for many adults with hematological malignancies. However, it can be associated with substantial risks of morbidity and mortality that are dependent on patient comorbidity- or disease risk-related factors. Several pretransplantation prognostic scoring systems have been developed to estimate survival of patients undergoing alloHCT; however, there is significant interstudy variability in the predictive capacity of these assessment tools. We tested the prognostic capability of a composite scoring system including the disease risk index and HCT comorbidity index (DRCI). The DRCI scoring system was applied pretransplantation to determine whether it predicted clinical outcomes of 959 adult patients with hematological malignancies undergoing alloHCT from 2000 to 2013 at the University of Minnesota. The DRCI score categorized patients into 6 risk groups, with 2-year overall survival ranging between 74% for the very low-risk DRCI group and 34% for the very high-risk DRCI group. In multiple regression analyses adjusted for patient age and donor type, the risk of overall mortality independently increased as the DRCI score increased. Additionally, the DRCI score independently predicted risk of relapse, disease-free survival, and graft-versus-host disease-free/relapse-free survival. Our data demonstrate that the pretransplantation DRCI scoring system predicts outcomes after alloHCT and can be used to guide clinical decision making for patients considering alloHCT.

Conditioning Intensity for Allogeneic Hematopoietic Cell Transplantation in Acute Myeloid Leukemia Patients with Poor-Prognosis Cytogenetics in First Complete Remission

The optimal intensity of conditioning regimen may be dependent on not only age and comorbidities but also disease characteristics and risk of relapse after allogeneic hematopoietic cell transplantation (HCT). We, therefore, analyzed the transplant outcomes of 840 adult patients with cytogenetically poor-risk acute myeloid leukemia (AML) in first complete remission (CR1) who received first allogeneic HCT with either myeloablative conditioning (MAC; n = 652) or reduced-intensity conditioning (RIC; n = 188) between 2006 and 2017. The median age at HCT was 50.5 years (range: 16 to 77 years). The multivariate analysis showed that patients receiving MAC had a significantly higher overall survival and lower leukemia-related mortality than those receiving RIC (P = .011 and P = .025, respectively). In the subgroup analysis, these results applied to patients aged 16 to 59 years, with HCT-comorbidity index scores ≥3, and with cytogenetic remission. Among MAC regimens, there was a trend for worse survival and nonrelapse mortality with the busulfan/fludarabine-based regimen compared with the total body irradiation (TBI) ≥8 Gy-based regimen (P = .082 and P = .062, respectively), whereas the busulfan/cyclophosphamide-based regimen and the fludarabine/melphalan-based regimen had similar outcomes with the TBI-based regimen. These data suggest that MAC is preferable to RIC for patients with cytogenetically poor-risk AML undergoing allogeneic HCT in CR1.

Impact of a novel prognostic model, hematopoietic cell transplant-composite risk (HCT-CR), on allogeneic transplant outcomes in patients with acute myeloid leukemia and myelodysplastic syndrome

Outcomes after allogeneic stem-cell transplantation (AHSCT) are influenced by both disease- and patient-related factors. Here, we developed a novel prognostic model, hematopoietic cell transplant-composite risk (HCT-CR), by combining the refined disease risk index (DRI-R) and hematopoietic stem-cell transplant comorbidity/age index (HCT-CI/Age) to predict post-transplant survival for patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). The analysis included 942 AML/MDS patients treated with AHSCT. Patients were stratified into 4 HCT-CR risk groups: Low-risk-patients with low/intermediate DRI-R and HCT-CI/Age ≤3 (N = 272); Intermediate-risk-patients with low/intermediate DRI-R and HCT-CI/Age >3 (N = 168); High-risk-patients with high/very high DRI-R and HCT-CI/Age ≤3 (N = 284); and Very high-risk-patients with high/very high DRI-R and HCT-CI/Age >3 (N = 184). Compared with the low-risk group, intermediate, high, and very high-risk groups had a significantly increased risk of death [adjusted HR of 1.37 (P < 0.04), 2.08 (P < 0.001), and 2.92 (P < 0.001), respectively]. The concordance test showed that the HCT-CR model provided better discriminative capacity for OS prediction compared with all prior models independently, including cytogenetic risk group, DRI-R, and HCT-CI/Age model (C-indices: 0.62, 0.55, 0.60, and 0.54, respectively) (P < 0.001). In conclusion, combining disease- and patient-related factors provides better survival stratification for patients with AML/MDS receiving AHSCT.

Allogeneic hematopoietic cell transplantation in adult acute myeloid leukemia with 11q23 abnormality: a retrospective study of the Adult Acute Myeloid Leukemia Working Group of the Japan Society for Hematopoietic Cell Transplantation (JSHCT)

An 11q23 abnormality presents in approximately 5% of adults with acute myeloid leukemia (AML) and is associated with adverse outcomes even after allogeneic hematopoietic cell transplantation (allo-HCT). To evaluate the outcomes and prognostic factors following allo-HCT for adult AML with 11q23 abnormality, we retrospectively analyzed the Japanese registration data of 322 adult AML patients with 11q23 abnormality who had received allo-HCT between 1990 and 2014. In total, the disease status at HCT was first complete remission (CR1) in 159 (49%) patients. The probability of overall survival and the cumulative incidence of relapse at 3 years were 44 and 44%, respectively. In the multivariate analysis, disease status beyond CR1 at the time of HCT was significantly associated with a higher overall mortality and relapse. The 11q23 fusion partner did not have a significant impact on survival. We also evaluated the prognostic value of minimal residual disease (MRD) status at HCT on transplant outcomes among hematological CR patients. MRD status at HCT was the significant prognostic indicator for hematological relapse and survival. These data suggested that allo-HCT offered a curative option for adult AML with 11q23 abnormality. Pretransplant MRD status was the significant prognostic indicator for relapse and survival in CR patients.

Cytogenetic clonal heterogeneity is not an independent prognosis factor in 15-60-year-old AML patients: results on 1291 patients included in the EORTC/GIMEMA AML-10 and AML-12 trials

The presence of cytogenetic clonal heterogeneity has been associated with poor prognosis in patients with acute myeloid leukemia (AML). Here, we reassessed this association. The study cohort consisted of all patients with an abnormal karyotype randomized in the EORTC/GIMEMA AML-10 and AML-12 trials. Abnormal karyotypes were classified as no subclones present (cytogenetic abnormality in a single clone), defined subclones present (presence of one to three subclones), and composite karyotypes (CP) (clonal heterogeneity not allowing enumeration of individual subclones). The main endpoints were overall survival (OS) and disease-free survival (DFS). Among 1291 patients with an abnormal karyotype, 1026 had no subclones, 226 at least 1 subclone, and 39 a CP. Patients with defined subclones had an OS similar to those with no subclones (hazard ratio (HR) 1.05, 95% confidence interval (CI) 0.88-1.26), but CP patients had a shorter OS (HR = 1.58, 95% CI 1.11-2.26). However, in a multivariate Cox model stratified by protocol and adjusted for age, cytogenetic risk group, secondary versus primary AML, and performance status, clonal heterogeneity lost its prognostic importance (HR = 1.10, 95% CI 0.91-1.32 for defined subclones versus no subclones; HR = 0.96, 95% CI 0.67-1.38 for CP versus no subclones). Also, the impact of having a donor on DFS was similar in the three clonal subgroups. In summary, in patients with cytogenetic abnormality, presence of subclones had no impact on OS. The dismal outcome in patients with a CP was explained by the known predictors of poor prognosis.

TRIAL REGISTRATION

AML-10: ClinicalTrials.gov identifier: NCT00002549, retrospectively registered July 19, 2004; AML12: ClinicalTrials.gov identifier: NCT00004128, registered January 27, 2003.

Initial Diagnostic Workup of Acute Leukemia: Guideline From the College of American Pathologists and the American Society of Hematology

CONTEXT

- A complete diagnosis of acute leukemia requires knowledge of clinical information combined with morphologic evaluation, immunophenotyping and karyotype analysis, and often, molecular genetic testing. Although many aspects of the workup for acute leukemia are well accepted, few guidelines have addressed the different aspects of the diagnostic evaluation of samples from patients suspected to have acute leukemia.

OBJECTIVE

- To develop a guideline for treating physicians and pathologists involved in the diagnostic and prognostic evaluation of new acute leukemia samples, including acute lymphoblastic leukemia, acute myeloid leukemia, and acute leukemias of ambiguous lineage.

DESIGN

- The College of American Pathologists and the American Society of Hematology convened a panel of experts in hematology and hematopathology to develop recommendations. A systematic evidence review was conducted to address 6 key questions. Recommendations were derived from strength of evidence, feedback received during the public comment period, and expert panel consensus.

RESULTS

- Twenty-seven guideline statements were established, which ranged from recommendations on what clinical and laboratory information should be available as part of the diagnostic and prognostic evaluation of acute leukemia samples to what types of testing should be performed routinely, with recommendations on where such testing should be performed and how the results should be reported.

CONCLUSIONS

- The guideline provides a framework for the multiple steps, including laboratory testing, in the evaluation of acute leukemia samples. Some aspects of the guideline, especially molecular genetic testing in acute leukemia, are rapidly changing with new supportive literature, which will require on-going updates for the guideline to remain relevant.

Haploidentical Hematopoietic Cell Transplant with Post-Transplant Cyclophosphamide and Peripheral Blood Stem Cell Grafts in Older Adults with Acute Myeloid Leukemia or Myelodysplastic Syndrome

Many hematologic malignancies are diseases of aging, and the use of hematopoietic cell transplant (HCT) is growing rapidly among older adults. Modern post-transplant cyclophosphamide (PTCy) protocols with haploidentical (haplo) donors have dramatically expanded the donor pool for patients requiring HCT. Initial studies were performed with bone marrow grafts, which require the donor to undergo anesthesia during harvest. However, the use of mobilized peripheral blood stem cells (PBSCs) may be desirable, especially with older donors. However, data on PBSC haplo-HCT in older adults are lacking. To characterize the impact of age on outcomes in haplo-HCT, we identified all adult patients undergoing haplo-HCT with PTCy for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) at our institution from January 2009 to June 2016. Patients were grouped into 3 cohorts: Age 1 (≤55), Age 2 (55 to 65), and Age 3 (≥65). To characterize the impact of donor type on outcomes in older patients, we identified age- and disease risk index (DRI)-matched patient age ≥ 65 undergoing HLA-matched unrelated donor (MUD) HCT for AML or MDS during the same time frame. Patients were scored for disease risk and underlying comorbidities using the DRI and HCT-specific comorbidity index. Overall survival (OS) was analyzed using 3 different Cox proportional hazards models. We identified 112 haplo-HCT patients, 95 with AML and 17 with MDS. There were 61 patients in Age 1, 29 patients in Age 2, and 22 in Age 3. Median OS was 448, 397, and 147 days in Age 1, Age 2, and Age 3 patients (log-rank, P = .04). After adjusting for other risk factors, age ≥ 65 was associated with significantly worse OS after haplo-HCT (aHR, 2.16; 95% CI, 1.15 to 4.07). There was a trend toward increased relapse among older patients at 2 years (56%; 95% CI, 32% to 79%) versus Age 1 (41%; 95% CI, 28% to 54%) and Age 2 (31%; 95% CI, 12% to 50%) (P = .08). Among patients age ≥ 65, donor type (MUD versus haplo) did not impact OS (aHR, 1.03; 95% CI, .56 to 1.88) after adjusting for other risk factors. Prior allo-HCT (aHR, 4.95; 95% CI, 1.82 to 13.49) and myeloablative conditioning (aHR, 1.97; 95% CI, 1.04 to 3.73) were associated with inferior survival. Although age ≥ 65 was associated with inferior OS in our haplo-HCT cohort, no difference was seen in survival between MUD and haplo-HCT. Therefore, the use of haploidentical donors in older patients is a reasonable treatment option, especially if there is concern for clinical deterioration. A careful pretransplant evaluation and analysis of risks and benefits is warranted when offering this transplant modality to older adults, especially in patients with previous transplant or poor performance status. Strategies to reduce the risk of relapse and decrease nonrelapse mortality in older adults are areas of ongoing research, and prospective studies are needed.

Healthcare Costs and Utilization for Patients Age 50 to 64 Years with Acute Myeloid Leukemia Treated with Chemotherapy or with Chemotherapy and Allogeneic Hematopoietic Cell Transplantation

The primary aim of this study was to describe healthcare costs and utilization during the first year after a diagnosis of acute myeloid leukemia (AML) for privately insured non-Medicare patients in the United States aged 50 to 64 years who were treated with either chemotherapy or chemotherapy and allogeneic hematopoietic cell transplantation (alloHCT). MarketScan (Truven Health Analytics) adjudicated total payments for inpatient, outpatient, and prescription drug claims from 2007 to 2011 were used to estimate costs from the health system perspective. Stabilized inverse propensity score weights were constructed using logistic regression to account for differential selection of alloHCT over chemotherapy. Weighted generalized linear models adjusted costs and utilization (hospitalizations, inpatient days, and outpatient visit-days) for differences in age, sex, diagnosis year, region, insurance plan type, Elixhauser Comorbidity Index), and 60-day prediagnosis costs. Because mortality data were not available, models could not be adjusted for survival times. Among 29,915 patients with a primary diagnosis of AML, 985 patients met inclusion criteria (774 [79%] receiving chemotherapy alone and 211 [21%] alloHCT). Adjusted mean 1-year costs were $280,788 for chemotherapy and $544,178 for alloHCT. Patients receiving chemotherapy alone had a mean of 4 hospitalizations, 52.9 inpatient days, and 52.4 outpatient visits in the year after AML diagnosis; patients receiving alloHCT had 5 hospitalizations, 92.5 inpatient days, and 74.5 outpatient visits. Treating AML in the first year after diagnosis incurs substantial healthcare costs and utilization with chemotherapy alone and with alloHCT. Our analysis informs healthcare providers, policymakers, and payers so they can better understand treatment costs and utilization for privately insured patients aged 50 to 64 with AML.

Outcome of allogeneic hematopoietic stem cell transplantation in adult patients with acute myeloid leukemia harboring trisomy 8

Trisomy 8 (+8) is one of the most common cytogenetic abnormalities in adult patients with acute myeloid leukemia (AML). However, the outcome of allogeneic hematopoietic stem cell transplantation (HSCT) in adult patients with AML harboring +8 remains unclear. To evaluate, the outcome and prognostic factors in patients with AML harboring +8 as the only chromosomal abnormality or in association with other abnormalities, we retrospectively analyzed the Japanese registration data of 631 adult patients with AML harboring +8 treated with allogeneic HSCT between 1990 and 2013. In total, 388 (61%) patients were not in remission at the time of HSCT. With a median follow-up of 38.5 months, the probability of overall survival and the cumulative incidence of relapse at 3 years were 40 and 34%, respectively. In the multivariate analysis, two or more additional cytogenetic abnormalities and not being in remission at the time of HSCT were significantly associated with a higher overall mortality and relapse. Nevertheless, no significant impact on the outcome was observed in cases with one cytogenetic abnormality in addition to +8. Although more than 60% of the patients received HSCT when not in remission, allogeneic HSCT offered a curative option for adult patients with AML harboring +8.

Impact of Pretransplantation Indices in Hematopoietic Stem Cell Transplantation: Knowledge of Center-Specific Outcome Data Is Pivotal before Making Index-Based Decisions

Outcome after allogeneic hematopoietic stem cell transplantation is influenced by patient comorbidity, disease type, and status before treatment. We performed a retrospective study involving 521 consecutive adult hematopoietic stem cell transplantation patients who underwent transplantation for hematological malignancy at our center from 2000 to 2012 to compare the predictive value of the hematopoietic cell transplantation-specific comorbidity index (HCT-CI) and the disease risk index (DRI) for overall survival and transplantation-related mortality. Patients in the highest HCT-CI risk group (HCT-CI score ≥3) had a lower 5-year overall survival rate (50%) than the low-risk group (63%; P < .01). Subset analysis of donor origin showed greater 5-year overall survival in siblings than in matched unrelated donors, regardless of HCT-CI score (eg, 67% 5-year overall survival in siblings despite an HCT-CI score of >6 [n = 9]). Five-year overall survival in the highest DRI risk group was significantly poorer (44%) than in the low-risk group (63%; P < .01). Both indices failed to predict differences in transplantation-related mortality (HCT-CI, P = .54; DRI, P = .17). We conclude that HCT-CI and DRI were predictive of overall survival in our patient population. Even so, our data show that different patient groups may have different outcomes despite sharing the same index risk group and that indices should, therefore, be evaluated according to local data before clinical implementation at the single-center level.

Clinical Utility of Next-Generation Sequencing for Oncogenic Mutations in Patients with Acute Myeloid Leukemia Undergoing Allogeneic Stem Cell Transplantation

To determine the association of somatic mutations in acute myeloid leukemia (AML) with risk of relapse after allogeneic hematopoietic stem cell transplantation (alloHSCT), we retrospectively studied pre-transplantation genetic profiles obtained from next-generation sequencing of 26 genes in 112 adult patients with AML who underwent alloHSCT. Univariable and multivariable regression analyses were used to assess the association between the presence of a pathogenic mutation and risk of relapse after alloHSCT. Eighty-six percent (96 of 112) of patients had at least 1 pathogenic mutation. Mutations in TP53, WT1, and FLT3-internal tandem duplication (ITD) were associated with an increased risk of relapse after alloHSCT (adjusted hazard ratio [aHR], 2.90; P = .009; aHR, 2.51; P= .02; and aHR, 1.83; P = .07, respectively). DNMT3A mutation in the absence of FLT3-ITD and NPM1 mutations was associated with a lower relapse risk (aHR, .22; P = .04). Comparison of pre-alloHSCT and post-alloHSCT genetic profiles showed clonal evolution in 6 of 6 patients, including acquisition of actionable mutations in 4 patients. In summary, genetic profiling is useful for assessing relapse risk in patients with AML undergoing alloHSCT and may identify patients in need of strategies to reduce this risk. Clonal evolution is present at post-alloHSCT relapse and repeat genetic profiling may uncover acquired actionable mutations.

Post-Transplantation Natural Killer Cell Count: A Predictor of Acute Graft-Versus-Host Disease and Survival Outcomes After Allogeneic Hematopoietic Stem Cell Transplantation

BACKGROUND

Reconstitution of the immune system after allogeneic hematopoietic stem cell transplantation (allo-HSCT) plays an important role in post-transplant outcomes. However, the clinical relevance of the lymphocyte subset (LST) counts to transplant-related complications and survival outcomes after allo-HSCT has not been fully elucidated.

PATIENTS AND METHODS

A total of 70 patients who had undergone allo-HSCT from 2007 to 2013, with LST results both 7 days before conditioning and 30 or 90 days after allo-HSCT were included. The LST counts in the peripheral blood were determined using 6-color flow cytometry. Clinical information, including transplant-related events during the first 100 days after allo-HSCT, was reviewed, and any association between these events and LST was analyzed.

RESULTS

At 30 days after allo-HSCT, the CD4⁺ T-cell (P = .009) and B-cell (P = .035) counts were lower and the natural killer (NK) cell count was greater (P < .001) than before conditioning. The CD8⁺ T-cell (P = .001) and NK cell (P < .001) counts were high 90 days after transplantation. The hazard ratios for a low NK cell count on days 30 and 90 for acute graft-versus-host disease were 6.22 and 14.67, respectively. Patients with low NK cell counts at 30 and 90 days after allo-HSCT had poorer overall survival (P = .043 and P = .028, respectively) and greater nonrelapse mortality (P = .036 and P = .033, respectively). A low NK cell count on day 30 was still prognostic for overall survival (P = .039) on multivariable analysis.

CONCLUSION

NK cell counts after allo-HSCT, especially on day 30, were predictive of acute graft-versus-host disease, nonrelapse mortality, and survival. Serial lymphocyte subset analysis can be used to identify and treat patients at risk during the early period after allo-HSCT.

Up-to-date tools for risk assessment before allogeneic hematopoietic cell transplantation

Cure of malignant and non-malignant hematological diseases is potentially possible after allogeneic hematopoietic stem cell transplantation (HCT). Accurate evaluation of the risk-benefit ratio for an individual patient could improve the decision-making process about transplant, which ultimately would increase the likelihood of success. Several transplant-related models were designed in an effort to optimize decision-making about suitable candidates for allogeneic HCT. In 1998, The European Society for Blood and Marrow Transplantation (EBMT) developed a five-component pretransplantation risk scoring system for patients with CML. The EBMT score was later tested in patients with various hematological disorders, and it was shown to stratify risks of mortality after allogeneic HCT. More recent research efforts focused on models that assess health status before HCT. A HCT-specific comorbidity index was designed to assign weights to 17 relevant comorbidities that were shown to independently predict non-relapse mortality. Performance status scales and comprehensive geriatric assessment tools might uncover additional overall health limitations that affect long-term survival among older recipients of allogeneic HCT. Other models include the pretransplantation assessment of mortality score that summarizes the impacts of eight different pretransplantation patient- and disease-specific variables into a 50-point model that predicts survival. The disease-risk index captures the impact of primary diagnoses and disease status on relapse and survival following allogeneic HCT. The values and limitations of each model are discussed herein. We also provide insight on how to use these models in the clinic to decide about offering allogeneic HCT with the most suitable conditioning regimen intensity.

Hematopoietic Cell Transplantation Outcomes in Monosomal Karyotype Myeloid Malignancies

The presence of monosomal karyotype (MK+) in acute myeloid leukemia (AML) is associated with dismal outcomes. We evaluated the impact of MK+ in AML (MK+AML, n = 240) and in myelodysplastic syndrome (MDS) (MK+MDS, n = 221) on hematopoietic cell transplantation outcomes compared with other cytogenetically defined groups (AML, n = 3360; MDS, n = 1373) as reported to the Center for International Blood and Marrow Transplant Research from 1998 to 2011. MK+ AML was associated with higher disease relapse (hazard ratio, 1.98; P < .01), similar transplantation-related mortality (TRM) (hazard ratio, 1.01; P = .90), and worse survival (hazard ratio, 1.67; P < .01) compared with those outcomes for other cytogenetically defined AML. Among patients with MDS, MK+ MDS was associated with higher disease relapse (hazard ratio, 2.39; P < .01), higher TRM (hazard ratio, 1.80; P < .01), and worse survival (HR, 2.02; P < .01). Subset analyses comparing chromosome 7 abnormalities (del7/7q) with or without MK+ demonstrated higher mortality for MK+ disease in for both AML (hazard ratio, 1.72; P < .01) and MDS (hazard ratio, 1.79; P < .01). The strong negative impact of MK+ in myeloid malignancies was observed in all age groups and using either myeloablative or reduced-intensity conditioning regimens. Alternative approaches to mitigate disease relapse in this population are needed.

Patient age, remission status and HCT-CI in a combined score are prognostic for patients with AML undergoing allogeneic hematopoietic cell transplantation in CR1 and CR2

For AML, older age, advanced disease and increased hematopoietic cell transplant comorbidity index (HCT-CI) are associated with worse prognosis following allogeneic hematopoietic cell transplantation (HCT). This single-center retrospective study investigated the influence of pre-transplant characteristics on outcomes of 387 patients undergoing allogeneic HCT for AML in CR1 and CR2. The multivariable analysis model for overall survival (OS) included age (hazard ratio (HR)=2.24 for ages 31-64 years and HR=3.23 for age ⩾65 years compared with age ⩽30 years, P=0.003), remission status (HR=1.49 for CR2 compared with CR1, P=0.005) and HCT-CI score (HR=1.47 for ⩾3 compared with <3, P=0.005). Transplant year was significantly associated with OS (P=0.001) but this did not influence the model. A weighted score was developed with age ⩽30, CR1 and HCT-CI score <3 receiving 0 points each, and CR2 and HCT-CI score ⩾3 receiving 1 point each. Ages 31-64 received 2 points, age ⩾65 received 3 points. Scores were grouped as follows: scores 0-1 (low risk, n=36), score 2 (intermediate-low risk, n=147), score 3 (intermediate-high risk, n=141) and scores 4-5 (high risk, n=63) with 3-year OS of 71%, 55%, 42% and 29% for scores 0-1, 2, 3 and 4-5, respectively (P<0.0001). The score predicted nonrelapse mortality (P=0.03) but not cumulative incidence of relapse (P=0.18). This model should be validated for the pre-HCT assessment of AML patients in CR1 and CR2.

Immunotherapy in acute myeloid leukemia

Despite the remarkable progress made in some leukemias such as CML and CLL, cytotoxic treatment for AML remains essentially unchanged over the last 4 decades. Several lines of evidence, including the graft versus leukemia effect associated with allogeneic hematopoietic stem cell transplantation (HSCT), suggest that immunotherapy is an active modality in AML. Given the lack of progress for chemotherapy in this disease, many novel immunologic treatment approaches have been explored. The goals of non-transplant-based immune approaches have largely consisted of the stimulation or restoration of endogenous immune responses or the targeting of specific tumor antigens by immune cells. These strategies have been associated with less toxicity than allogeneic HSCT but typically have inferior efficacy. Allogeneic HSCT exploits major and minor histocompatibility differences between the donor and recipient in order to recognize and eradicate malignancy. With the recognition that the immune system itself provides a basis for treating AML, immunotherapy continues to be an attractive modality to exploit in the treatment of this disease.

Long-term outcome of HLA-haploidentical hematopoietic stem cell transplantation without in vitro T-cell depletion based on an FBCA conditioning regimen for hematologic malignancies

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) is an alternative for patients who need a transplant without having conventional donors. One hundred and five consecutive patients with hematologic malignancies who underwent G-CSF-primed peripheral blood haplo-HSCT without in vitro T-cell depletion in our single center were reported in this study. Patients were categorized into the intermediate-risk group (n=28) or high-risk group (n=77) according to the risk stratification. The conditioning regimen included fludarabine, busulfan, cyclophosphamide and anti-lymphocyte globulin. The cumulative incidence of grades II-IV acute GvHD (aGvHD) on day +100 was 21.9%, and that of grades III-IV aGvHD was 14.3%. The 2-year cumulative incidence of total chronic GvHD (cGvHD) was 24.1%, and that of extensive cGvHD was 5.6% in 83 eligible patients. The 3-year cumulative incidence rates of relapse and no relapse mortality were 21.9% and 30.5%, respectively. After a median follow-up of 35 months, the 3-year probabilities of overall and disease-free survival for the intermediate-risk and high-risk groups were 63.2% and 39.8% and 61.2% and 32.2%, respectively. In multivariate analysis, the outcome of survival (overall survival and disease-free survival) was associated with the risk stratification, disease status at transplant and dose of infused mononuclear cells. Our results suggest that unmanipulated peripheral blood stem cell allograft performed with fludarabine, busulfan, cyclophosphamide and anti-lymphocyte globulin conditioning regimen is feasible.

Haploidentical vs identical-sibling transplant for AML in remission: a multicenter, prospective study

The effects of HLA-identical sibling donor (ISD) hematopoietic stem cell transplantation (HSCT) on adults with intermediate- or high-risk acute myeloid leukemia (AML) in the first complete remission (CR1) are well established. Previous single-center studies have demonstrated similar survival after unmanipulated haploidentical donor (HID) vs ISD HSCT for hematologic malignancies. To test the hypothesis that haploidentical HSCT would be a valid option as postremission therapy for AML patients in CR1 lacking a matched donor, we designed a disease-specific, prospective, multicenter study. Between July 2010 and November 2013, 450 patients were assigned to undergo HID (231 patients) or ISD HSCT (219 patients) according to donor availability. Among HID and ISD recipients, the 3-year disease-free survival rate was 74% and 78% (P = .34), respectively; the overall survival rate was 79% and 82% (P = .36), respectively; cumulative incidences of relapse were 15% and 15% (P = .98); and those of the nonrelapse-mortality were 13% and 8% (P = .13), respectively. In conclusion, unmanipulated haploidentical HSCT achieves outcomes similar to those of ISD HSCT for AML patients in CR1. Such transplantation was demonstrated to be a valid alternative as postremission treatment of intermediate- or high-risk AML patients in CR1 lacking an identical donor. This trial was registered at www.chictr.org as #ChiCTR-OCH-10000940.

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.

Single-agent GVHD prophylaxis with posttransplantation cyclophosphamide after myeloablative, HLA-matched BMT for AML, ALL, and MDS

High-dose, posttransplantation cyclophosphamide (PTCy) reduces severe graft-versus-host disease (GVHD) after allogeneic blood or marrow transplantation (alloBMT), but the impact of PTCy on long-term, disease-specific outcomes is unclear. We conducted a retrospective study of 209 consecutive adult patients transplanted for acute myeloid leukemia (AML, n = 138), myelodysplastic syndrome (n = 28), or acute lymphoblastic leukemia (ALL, n = 43) using PTCy as sole GVHD prophylaxis after myeloablative conditioning and HLA-matched-related or -unrelated T-cell-replete allografting. At alloBMT, 30% of patients were not in morphologic complete remission. The cumulative incidences of grades II to IV and III to IV acute GVHD at 100 days and chronic GVHD at 2 years were 45%, 11%, and 13%, respectively. Forty-three percent of patients did not require immunosuppression for any reason beyond PTCy. At 3 years, relapse cumulative incidence was 36%, disease-free survival was 46%, survival free of disease and chronic GVHD was 39%, and overall survival was 58%. Lack of remission at alloBMT, adverse cytogenetics, and low allograft nucleated cell dose were associated with inferior survival for AML patients. Minimal residual disease but not t(9;22) was associated with inferior outcomes for ALL patients. The ability to limit posttransplantation immunosuppression makes PTCy a promising transplantation platform for the integration of postgrafting strategies to prevent relapse.