Hematopoietic cell transplantation in older patients with hematologic malignancies: replacing high-dose cytotoxic therapy with graft-versus-tumor effects

Clinical implications of SRSF2 mutations in AML patients undergoing allogeneic stem cell transplantation

The SRSF2 mutations are frequently found in acute myeloid leukemia (AML) and mostly affect the P95 residue. Mutations in this splicing factor mediate abnormal splicing associated with exon skipping events, including EZH2 as a crucial target. While SRSF2 mutations are enriched in secondary AML and associated with worse outcomes following chemotherapy consolidation, very little is known about the associated biological and clinical implications in AML patients consolidated with allogeneic hematopoietic stemcell transplantation (HSCT). Here we retrospectively analyzed 263 adult AML patients who received an allogeneic HSCT regarding the biological and clinical implications of the SRSF2 mutation status at diagnosis and in morphologic remission at HSCT. We found 12.5% of the patients to be SRSF2 mutated at diagnosis. Mutated patients had increased EZH2 missplicing events with P95H likely driving this pathobiology most effectively. However, the amount of EZH2 missplicing events, as a functional surrogate marker did not associate with relevant biological or clinical characteristics. We observed a persistence of mutations in remission before HSCT in the majority (93%) of SRSF2 mutated AML patients. Importantly, the variant allele frequency (VAF) levels of SRSF2 mutations in remission at HSCT did not correlate with outcomes following HSCT consolidation, limiting the applicability of SRSF2 mutations as a marker for residual AML disease. Following allogeneic HSCT SRSF2 mutated AML patients experienced a 2-year overall survival of 77%, indicating that SRSF2 mutated AML patients may benefit from HSCT consolidation.

Differential effects of donor lymphocyte infusion upon treatment response and GVHD according to relapse level and donor sources in patients with myelodysplastic syndrome

INTRODUCTION

Donor lymphocyte infusion (DLI) is one of the effective options for post-transplant disease control of myelodysplastic syndrome (MDS). Its success or failure depends on the induction of antitumor immune reactions, durability of clinical responses, and severity of unwanted toxicities mainly from graft-versus-host disease (GVHD).

METHODS

By analyzing 61 patients receiving DLI for post-transplant MDS relapse, we assessed treatment outcomes and affecting factors, especially focusing on the level of relapse (hematological, molecular, and imminent relapse).

RESULTS

The response rate (42.1%, 36.4%, 72.7%), and overall survival (OS) at 2 years (27.8%, 45.5%, 70.1%) were different for each relapse level with imminent relapse group showing the most promising results. For OS, response to DLI or pre-DLI chemotherapy, and time to relapse were independent prognostic factors. Meanwhile, post-DLI GVHD and time to relapse were independently predictive for DLI response; post-DLI GVHD was predictive for DLI response, but not for OS, suggesting a potential detrimental impact of GVHD on survival. The incidence of GVHD and GVHD-related deaths were 37.7% and 10.0%, respectively, and CD3+ cell doses triggering GVHD tended to be lower in cases with haploidentical donor or imminent relapse.

CONCLUSION

Despite being limited by small number of cases and its retrospective nature, this study again demonstrated the therapeutic effects of DLI in relapsed MDS, and that earlier detection and intervention at lower level relapse might possibly be associated with better results. Furthermore, we propose that tailored cell dosing schedule based on relapse level and donor source may be helpful in minimizing fatal GVHD.

60 Years Young: The Evolving Role of Allogeneic Hematopoietic Stem Cell Transplantation in Cancer Immunotherapy

The year 2020 marked the 30th anniversary of the Nobel Prize in Medicine awarded to E. Donnall Thomas for the development of allogeneic hematopoietic stem cell transplantation (allo-HSCT) to treat hematologic malignancies and other blood disorders. Dr. Thomas, "father of bone marrow transplantation," first developed and reported this technique in 1957, and in the ensuing decades, this seminal study has impacted fundamental work in hematology and cancer research, including advances in hematopoiesis, stem cell biology, tumor immunology, and T-cell biology. As the first example of cancer immunotherapy, understanding the mechanisms of antitumor biology associated with allo-HSCT has given rise to many of the principles used today in the development and implementation of novel transformative immunotherapies. Here we review the historical basis underpinning the development of allo-HSCT as well as advances in knowledge obtained by defining mechanisms of allo-HSCT activity. We review how these principles have been translated to novel immunotherapies currently utilized in clinical practice and describe potential future applications for allo-HSCT in cancer research and development of novel therapeutic strategies.

New nonchemotherapy treatment options for cutaneous T-cell lymphomas

INTRODUCTION

The most common types of CTCL are mycosis fungoides (MF) and Sézary syndrome (SS). In both MF and SS, complete responses to treatment are uncommon. Recent developments and understanding of the biology of MF/SS have led to novel agents which may offer prolonged responses with less toxicity compared to conventional chemotherapy approaches.

AREAS COVERED

In this review, we discuss the efficacy and safety of new nonchemotherapy treatment options including antibody agents, small molecule inhibitors, fusion proteins, and CAR T-cell therapy. We also reflect on older immunomodulatory treatments including retinoids and histone deacetylase inhibitors.

EXPERT OPINION

Patients with MF/SS who require systemic therapy often progress through multiple agents sequentially, thus the need for additional novel agents in the treatment armamentarium. Antibody-based therapies such as alemtuzumab are highly effective in the blood compartment of disease, while brentuximab vedotin has shown higher activity in skin and lymph nodes. Checkpoint inhibitors may play a role in treating MF/SS but may induce hyperprogression, and engineered T cells and bispecific antibodies recruiting immune effectors are being developed and may show promise in the future.

TRough versus AUC Monitoring of cyclosporine: A randomized comparison of adverse drug reactions in adult allogeneic stem cell recipients (TRAM study)

OBJECTIVE

To investigate the incidence and severity of adverse drug reactions of cyclosporine using AUC-targeted therapeutic drug monitoring (TDM) compared to trough level (C_trough )-targeted TDM in adult allogeneic stem cell recipients.

METHODS

Blind, monocenter, intervention study. Subjects were 1:1 randomized into either an AUC group or a C_trough group. Adverse drug reactions were accessed two and four weeks after start of treatment.

RESULTS

Forty patients were included, resulting in 15 evaluable subjects (AUC group) and 13 evaluable subjects (C_trough group). Grade two/three toxicity was observed in 46% (C_trough group) versus 60% of subjects (AUC group) (P = .463). There was no significant difference between two and four weeks after start of cyclosporine for nausea (P = .142 resp. P = .122), renal dysfunction (P = .464 resp. P = 1.000), and hypomagnesemia (P = 1.000 resp. P = .411). Subjects in the AUC group reached the therapeutic goal earlier (72,7% versus 43,0% at third sampling point, P = .332) and were within the target range more consistently.

CONCLUSION

This study showed no reduction in incidence and severity of cyclosporine-induced toxicity with AUC- versus trough level-targeted TDM. Although modeled dosing based on AUC led to faster optimal target attainment, this did not result in less toxicity in the early days after transplantation.

A Limited Sampling Strategy for Therapeutic Drug Monitoring of Mycophenolate Mofetil for Prophylaxis of Acute Graft-Versus-Host Disease in Allogeneic Stem Cell Transplantation

A universally accepted strategy for therapeutic drug monitoring (TDM) of mycophenolate mofetil (MMF) in the prevention of acute graft-versus-host disease (aGVHD) in allogenic hematopoietic stem cell transplantation (alloHSCT) does not exist. We explored the feasibility of developing a limited sampling strategy (LSS) for TDM of MMF in this setting. Patients undergoing alloHSCT received standard MMF-cyclosporine prophylaxis, with MMF administered twice daily (BD) for matched transplant recipients or thrice daily (TID) in haploidentical transplantation. Intensive blood sampling was carried out on day 7 and area under the concentration–time curve (AUC) of mycophenolic acid (MPA), the active metabolite, was estimated using noncompartmental analysis. The ability of MPA exposure defined by AUC_0-12 to discriminate between responders (patients who did not develop GVHD) and nonresponders (patients who developed GVHD) was determined by receiver operating characteristic curve analysis. Patients were divided into training and validation sets within BD and TID groups. Mathematical equations were developed from the training set to predict AUC_0-12 from an abbreviated AUC involving a limited number of sampling points. The equations were validated in the validation set by comparing the MPA AUC_0-12 predicted from LSS with the observed AUC_0-12. It was observed that patients with AUC_0-12 ≤18.99 mg*h/L had a higher risk of developing aGVHD [odds ratio (OR) = 2.63 (1.17 to 5.87), P = 0.06]. The benefit was more in matched transplant recipients [OR = 3.5 (1.30 to 9.49), P = 0.05] as compared to haploindentical transplant [OR = 2.8 (0.49 to 15.91), P = NS]. Using the mathematical equations, the observed AUC_0-12 was predicted with 92.31% accuracy in the BD subset and 100% accuracy in the TID subset for a combined accuracy of 94.76%. A set of just three samples that constituted the abbreviated AUC_1-4 was used to develop the predictive models. The LSS could be employed for the therapeutic monitoring of MMF particularly in patients undergoing matched hematopoietic stem cell transplantation.

How we treat advanced stage cutaneous T-cell lymphoma - mycosis fungoides and Sézary syndrome

T-cell lymphomas (TCLs) constitute a rare subset of non-Hodgkin lymphomas, with mycosis fungoides/Sézary syndrome (MF/SS) being the most common subtype of cutaneous TCLs (CTCLs). Considered an incurable but treatable disease, MF/SS management presents several challenges including diagnostic delays, debilitating effect on patients' quality of life, need for several lines of therapies, multidisciplinary care and cumulative drug toxicities limiting duration of use. The present review intends to provide an overview of the recent advances in our understanding of the biology of CTCL and how these are being leveraged to provide additional treatment options for management of advanced and recurrent disease. In addition, the discussion of the different modalities of treatment is summarised to further outline the importance of multidisciplinary care and early referral to CTCL centres.

Prognostic impact of the ELN2017 risk classification in patients with AML receiving allogeneic transplantation

In 2017, an updated European LeukemiaNet (ELN) risk classification was published allocating patients with acute myeloid leukemia (AML) to 3 risk groups on the basis of certain cytogenetic and molecular aberrations. To date, studies of the prognostic significance of the ELN2017 risk classification in the context of an allogeneic hematopoietic stem cell transplantation (HSCT) are lacking. We performed risk stratification according to the ELN2017 classification in 234 patients with AML who underwent allogeneic HSCT as a consolidation therapy. In our cohort, the risk of 39.7% of the patients was classified as favorable, that of 12.8% as intermediate, and that of 47.4% as adverse. In the context of allogeneic HSCT, the assignment to the 3 ELN2017 risk groups retained its prognostic significance, with patients with favorable risk having the best prognosis and those with adverse risk having the worst one. Subgroup analyses showed that patients with a monosomal karyotype or TP53 mutation had considerably increased relapse rates, even in the adverse-risk group. When we analyzed the impact of digital droplet PCR-based measurable residual disease (MRD) before allogeneic HSCT, MRD+ patients had impaired prognoses, with cumulative incidence of relapse and overall survival comparable to those of patients classified as having an ELN2017 adverse genetic risk. This study is the first to demonstrate that the ELN2017 classification distinguishes the 3 risk groups with significantly distinct prognoses, even after allogeneic HSCT, and emphasizes the dismal prognosis of patients with AML with TP53 mutations, monosomal karyotype, or MRD positivity after allogeneic HSCT.

Outcomes of Fludarabine, Melphalan and Total Body Irradiation as a Reduced Intensity Conditioning Regimen in Matched Donor Allogeneic Peripheral Blood Stem Cell Transplantation

Fludarabine 30 mg/m²/d × 5 and melphalan 140 mg/m² × 1 (Flu-Mel140) is a commonly used reduced-intensity conditioning regimen. We hypothesized that addition of 200cGy total body irradiation (TBI) to Flu-Mel140 may improve antitumor activity and transplant outcomes. Primary objectives was overall survival (OS) at 3 years. Secondary objectives were to assess the cumulative incidences of acute and chronic GVHD, relapse-free survival (RFS), relapse rate, and nonrelapse mortality (NRM). We retrospectively evaluated outcomes of patients receiving Flu-Mel140-TBI followed by HLA-matched donor allogeneic hematopoietic stem cell transplantation (alloSCT) using peripheral blood stem cells. Eighty-one patients (median age, 58 years) underwent alloSCT between January 2008 and December 2018. Thirty-one percent of patients had a prior transplant, 32% had high or very-high disease risk index, and the donor was unrelated in 70% of patients. Grade 3 to 4 regimen-related toxicities were mucositis (37%), cardiac toxicity (17%), and renal toxicity (10%). The cumulative incidence of grade III to IV acute GVHD at day +100 was 24.7% and chronic GVHD at 1 year was 51.3%. Median follow-up for survival was 6.1 years. At 3 years, OS was 39.81%, RFS was 31.47%, and relapse rate was 30.5%. One-year NRM was 29.9%. Patients undergoing first transplantation experienced improved OS compared with second or beyond (63.08% versus 42.31%, P = .02). After adjusting for disease subtypes, age (≤55 versus 55), comorbidity index (CI), number of transplant and GVHD prophylaxis, multivariable analysis did not demonstrate any survival difference among disease subtypes. High CI (≥3) was predictive of adverse OS and NRM, whereas older age (>55 years) was associated with high NRM. Our study shows that Flu-Mel140-TBI seems feasible and provides durable disease control. Addition of TBI did not appear to improve outcomes compared to previously published reports of Flu-Mel140. Considerable NRM could result from the inclusion of patients with older age and prior transplants.

Reduced intensity conditioning for acute myeloid leukemia using melphalan- vs busulfan-based regimens: a CIBMTR report

There is a lack of large comparative study on the outcomes of reduced intensity conditioning (RIC) in acute myeloid leukemia (AML) transplantation using fludarabine/busulfan (FB) and fludarabine/melphalan (FM) regimens. Adult AML patients from Center for International Blood and Marrow Transplant Research who received first RIC allo-transplant between 2001 and 2015 were studied. Patients were excluded if they received cord blood or identical twin transplant, total body irradiation in conditioning, or graft-versus-host disease (GVHD) prophylaxis with in vitro T-cell depletion. Primary outcome was overall survival (OS), secondary end points were leukemia-free survival (LFS), nonrelapse mortality (NRM), relapse, and GVHD. Multivariate survival model was used with adjustment for patient, leukemia, and transplant-related factors. A total of 622 patients received FM and 791 received FB RIC. Compared with FB, the FM group had fewer transplant in complete remission (CR), fewer matched sibling donors, and less usage of anti-thymocyte globulin or alemtuzumab. More patients in the FM group received marrow grafts and had transplantation before 2005. OS was significantly lower within the first 3 months posttransplant in the FM group (hazard ratio [HR] = 1.82, P < .001), but was marginally superior beyond 3 months (HR = 0.87, P = .05). LFS was better with FM compared with FB (HR = 0.89, P = .05). NRM was significantly increased in the FM group during the first 3 months of posttransplant (HR = 3.85, P < .001). Long-term relapse was lower with FM (HR = 0.65, P < .001). Analysis restricted to patients with CR showed comparable results. In conclusion, compared with FB, the FM RIC showed a marginally superior long-term OS and LFS and a lower relapse rate. A lower OS early posttransplant within 3 months was largely the result of a higher early NRM.

Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia: Who, When, and How?

Although the majority of patients with acute myeloid leukemia (AML) treated with intensive chemotherapy achieve a complete remission (CR), many are destined to relapse if treated with intensive chemotherapy alone. Allogeneic stem cell transplant (allo-SCT) represents a pivotally important treatment strategy in fit adults with AML because of its augmented anti-leukemic activity consequent upon dose intensification and the genesis of a potent graft-versus-leukemia effect. Increased donor availability coupled with the advent of reduced intensity conditioning (RIC) regimens has dramatically increased transplant access and consequently allo-SCT is now a key component of the treatment algorithm in both patients with AML in first CR (CR1) and advanced disease. Although transplant related mortality has fallen steadily over recent decades there has been no real progress in reducing the risk of disease relapse which remains the major cause of transplant failure and represents a major area of unmet need. A number of therapeutic approaches with the potential to reduce disease relapse, including advances in induction chemotherapy, the development of novel conditioning regimens and the emergence of the concept of post-transplant maintenance, are currently under development. Furthermore, the use of genetics and measurable residual disease technology in disease assessment has improved the identification of patients who are likely to benefit from an allo-SCT which now represents an increasingly personalized therapy. Future progress in optimizing transplant outcome will be dependent on the successful delivery by the international transplant community of randomized prospective clinical trials which permit examination of current and future transplant therapies with the same degree of rigor as is routinely adopted for non-transplant therapies.

Comparison of Myeloablative versus Reduced-Intensity Conditioning Regimens in Allogeneic Stem Cell Transplantation Recipients with Acute Myelogenous Leukemia with Measurable Residual Disease-Negative Disease at the Time of Transplantation: A Retrospective Cohort Study

The ideal conditioning intensity in allogeneic hematopoietic stem cell transplantation (HSCT) is evolving. Previous prospective studies comparing myeloablative conditioning (MAC) versus reduced-intensity conditioning (RIC) regimens in adults with acute myelogenous leukemia (AML) have shown mixed results. In many of these studies, patients were not stratified based on measurable residual disease (MRD). We evaluated the effect of conditioning intensity on the outcomes of AML patients in complete remission (CR) with flow cytometry evidence of MRD negativity. A total of 135 patients age 20 to 75 years with AML in CR1 or CR2 and flow cytometry evidence of MRD negativity who underwent allogeneic HSCT at our center between 2011 and 2019 were evaluated. We compared overall survival (OS), relapse-free survival (RFS), nonrelapse mortality (NRM), relapse, and acute and chronic graft-versus-host disease (GVHD) in recipients of MAC (n = 89) and RIC (n = 46). Although the patients receiving RIC were older (62 versus 51 years; P < .0001), there were no statistically significant differences between the groups in terms of Eastern Cooperative Oncology Group and European Leukemia Network risk criteria and disease status (CR1 or CR2) at the time of transplantation. At a median follow-up of 24.6 months, no statistically significant differences in OS (hazard ratio [HR], 0.78; 95% confidence interval [CI] 0.42 to 1.42, P = .411) or RFS (HR, 1.004; 95% CI, 0.48 to 2.09, P = .99) were identified. The cumulative incidence of NRM (HR, 0.595; 95% CI, 0.24 to 1.48; P = .2644) and relapse (HR, 1.007; 95% CI, 0.45 to 2.23; P = .9872) was not different between the 2 groups. Grade II-IV and grade III-IV acute GVHD were more frequent in the MAC group (39.3% verses 19.9% [P = .018] and 19.3% versus 2.3% [P < .001], respectively), as was moderate/severe chronic GVHD (23.6% versus 15.8%; P = .038). Our data indicate that conditioning intensity did not appear to affect OS, RFS, NRM, and relapse risk in patients with MRD-negative AML as measured by flow cytometry. RIC resulted in less severe acute and chronic GVHD.

Sirolimus with CSP and MMF as GVHD prophylaxis for allogeneic transplantation with HLA antigen-mismatched donors

This trial aimed to evaluate the efficacy of sirolimus in addition to cyclosporine (CSP) and mycophenolate mofetil (MMF) for graft-versus-host disease (GVHD) prophylaxis after nonmyeloablative conditioning for HLA class I or II mismatched hematopoietic cell transplantation (HCT). Eligible patients had hematologic malignancies treatable by allogeneic HCT. Conditioning consisted of fludarabine (90 mg/m2) and 2 to 3 Gy total body irradiation. GVHD prophylaxis comprised cyclosporine, mycophenolate mofetil, and sirolimus. The primary objective was to determine whether the cumulative incidence of grade 2 to 4 acute GVHD could be reduced to <70% in HLA class I or II mismatched HCT. The study was closed on December 20, 2018. Seventy-seven participants were recruited between April 14, 2011, and December 12, 2018, of whom 76 completed the study intervention. Median follow-up was 47 months (range, 4-94 months). The cumulative incidence of grade 2 to 4 acute GVHD at day 100 was 36% (95% confidence interval [CI], 25-46), meeting the primary end point. The cumulative incidence of nonrelapse morality, relapse/progression, and overall survival was 18% (95% CI, 9-27), 30% (interquartile range, 19-40), and 62% (95% CI, 50-73) after 4 years. In conclusion, the addition of sirolimus to cyclosporine and mycophenolate mofetil resulted in a lower incidence of acute GVHD, thus translating into superior overall survival compared with historical results. This trial was registered at www.clinicaltrials.gov as #NCT01251575.

Post-Transplant Cyclophosphamide and Tacrolimus-Mycophenolate Mofetil Combination Governs GVHD and Immunosuppression Need, Reducing Late Toxicities in Allogeneic Peripheral Blood Hematopoietic Cell Transplantation from HLA-Matched Donors

Combined direct antineoplastic activity and the long-lasting immunological effects of allogeneic hematopoietic cell transplant (HCT) can cure many hematological malignancies, but broad adoption requires non-relapse mortality (NRM) rates and graft-versus-host disease (GVHD) control. Recently, posttransplant cyclophosphamide (PTCy) given after a bone marrow transplant significantly reduced GVHD-incidence, while PTCy given with tacrolimus/mofetil mycophenolate (T/MMF) showed activity following allogeneic peripheral blood stem cell transplantation (alloPBSCT). Here, we report the experience of a larger cohort (85 consecutive patients) and expanded follow-up period (03/2011-12/2019) with high-risk hematological malignancies who received alloPBSCT from Human-Leukocyte-Antigens HLA-matched unrelated/related donors. GVHD-prophylaxis was PTCy 50 mg/kg (days+3 and +4) combined with T/MMF (day+5 forward). All patients stopped MMF on day+28 with day+110 = median tacrolimus discontinuation. Cumulative incidences were 12% for acute and 7% for chronic GVHD- and no GVHD-attributed deaths. For surviving patients, the 12, 24, and 36-month probabilities of being off immunosuppression were 92, 96, and 96%, respectively. After a 36-month median follow-up, NRM was 4%; median event-free survival (EFS) and overall survival (OS) had yet to occur. One- and two-year chronic GVHD-EFS results were 57% (95% CI, 46-68%) and 53% (95% CI, 45-61%), respectively, with limited late infections and long-term organ toxicities. Disease relapse caused the most treatment failures (38% at 2 years), but low transplant toxicity allowed many patients (14/37, 38%) to receive donor lymphocyte infusions as a post-relapse strategy. We confirmed that PTCy+T/MMF treatment effectively prevented acute and chronic GVHD and limited NRM to unprecedented low rates without loss of disease control efficacy in an expanded patient cohort. This trial is registered at U.S. National Library of Medicine as #NCT02300571.

Total Body Irradiation for Hematopoietic Stem Cell Transplantation: What Can We Agree on?

Total body irradiation (TBI), used as part of the conditioning regimen prior to allogeneic and autologous hematopoietic cell transplantation, is the delivery of a relatively homogeneous dose of radiation to the entire body. TBI has a dual role, being cytotoxic and immunosuppressive. This allows it to eliminate disease and create “space” in the marrow while also impairing the immune system from rejecting the foreign donor cells being transplanted. Advantages that TBI may have over chemotherapy alone are that it may achieve greater tumour cytotoxicity and better tissue penetration than chemotherapy as its delivery is independent of vascular supply and physiologic barriers such as renal and hepatic function. Therefore, the so-called “sanctuary” sites such as the central nervous system (CNS), testes, and orbits or other sites with limited blood supply are not off-limits to radiation. Nevertheless, TBI is hampered by challenging logistics of administration, coordination between hematology and radiation oncology departments, increased rates of acute treatment-related morbidity and mortality along with late toxicity to other tissues. Newer technologies and a better understanding of the biology and physics of TBI has allowed the field to develop novel delivery systems which may help to deliver radiation more safely while maintaining its efficacy. However, continued research and collaboration are needed to determine the best approaches for the use of TBI in the future.

Addition of Rituximab in Reduced Intensity Conditioning Regimens for B-Cell Malignancies Does Not Influence Transplant Outcomes: EBMT Registry Analyses Following Allogeneic Stem Cell Transplantation for B-Cell Malignancies

Rituximab (R) is increasingly incorporated in reduced intensity conditioning (RIC) regimens for allogeneic hematopoietic cell transplantation (alloHCT) in patients with B-cell malignancies, not only to improve disease control, but also to prevent graft-versus-host disease (GVHD). There are no randomized prospective data to validate this practice, although single center data and the CIBMTR analysis have shown promising results. We aimed at validation of these findings in a large registry study. We conducted a retrospective analysis using the EBMT registry of 3,803 adult patients with B-cell malignancies undergoing alloHCT (2001-2013) with either rituximab (R-RIC-9%) or non-rituximab (RIC-91%) reduced intensity regimens respectively. Median age and median follow up were 55 years (range 19.1-77.3) and 43.2 months (range 0.3-179.8), respectively. There was no difference in transplant outcomes (R-RIC vs RIC), including 1-year overall survival (69.9% vs 70.7%), 1-year disease-free survival (64.4% vs 62.2%), 1-year non-relapse mortality (21% vs 22%), and day-100 incidence of acute GVHD 2-4° (12% vs 12%). In summary, we found that addition of rituximab in RIC regimens for B-cell malignancies had no significant impact on major transplant outcome variables. Of note, data on chronic GVHD was not available, limiting the conclusions that can be drawn from the present study.

Comparison of Patient Age Groups in Transplantation for Myelodysplastic Syndrome: The Medicare Coverage With Evidence Development Study

Importance

In 2010, the US Centers for Medicare & Medicaid Services (CMS) indicated that data regarding efficacy of allogeneic hematopoietic stem cell transplantation (HCT) in the CMS beneficiary population with myelodysplastic syndrome (MDS) were currently insufficient, but that coverage would be provided for patients enrolled in a clinical study that met its criteria for Coverage with Evidence Development (CED).

Objective

The Center for International Bone Marrow Transplant Research (CIBMTR) submitted a study concept comparing the outcomes of patients aged 55 to 64 years vs aged 65 years or older who met those criteria, effectively providing coverage by CMS for HCT for MDS.

Design, Setting, and Participants

Data on patients aged 65 years or older were prospectively collected and their outcomes compared with patients aged 55 to 64 years. Patients were enrolled in the study from December 15, 2010, to May 14, 2014. The results reported herein were analyzed as of September 4, 2017, with a median follow-up of 47 months. The study was conducted by the CIBMTR. It comprises a voluntary working group of more than 420 centers worldwide that contribute detailed data on allogeneic and autologous HCT and cellular therapies.

Interventions

Patients with MDS received HCT according to institutional guidelines and preferences.

Main Outcomes and Measures

The primary outcome was overall survival (OS); secondary outcomes included nonrelapse mortality (NRM), relapse-free survival, and acute and chronic graft vs host disease.

Results

During the study period, 688 patients aged 65 years or older underwent HCT for MDS and were compared with 592 patients aged 55 to 64 years. Other than age, there were no differences in patient and disease characteristics between the groups. On univariate analysis, the 3-year NRM rate was 28% vs 25% for the 65 years or older group vs those aged 55 to 64 years, respectively. The 3-year OS was 37% vs 42% for the 65 years or older group vs the 55 to 64 years age group, respectively. On multivariable analysis after adjusting for excess risk of mortality in the older group, age group had no significant association with OS (HR, 1.09; 95% CI, 0.94-1.27; P = .23) or NRM (HR, 1.19; 95% CI, 0.93-1.52; P = .16).

Conclusions and Relevance

Older patients with MDS undergoing HCT have similar OS compared with younger patients. Based on current data, we would recommend coverage of HCT for MDS by the CMS.

Trial Registration

ClinicalTrials.gov identifier: NCT01166009.

Long-term Outcomes with Nonmyeloablative HLA-Identical Related Hematopoietic Cell Transplantation Using Tacrolimus and Mycophenolate Mofetil for Graft-versus-Host Disease Prophylaxis

Nonmyeloablative allogeneic hematopoietic cell transplantation (HCT) from HLA-identical related donors using cyclosporine (CSP) and mycophenolate mofetil (MMF) for postgrafting immunosuppression is effective therapy for hematologic cancers. However, graft-versus-host-disease (GVHD) remains a major cause of morbidity and mortality. Pilot data suggested lower acute GVHD incidence with tacrolimus/MMF compared to historical experience using CSP/MMF after nonmyeloablative HCT. In a phase II multicenter trial, we evaluated the effect of tacrolimus/MMF for GVHD prophylaxis after HLA-identical related donor peripheral blood HCT in patients with hematologic malignancies (n = 150) using conditioning with 2 Gy total body irradiation (TBI) for patients with a preceding (within 6 months) planned autologous HCT (n = 50) or combined with 90 mg/m² fludarabine for those without recent autologous HCT (n = 100). Oral tacrolimus was given from days -3 to 56 (tapered by day +180 if no GVHD). Oral MMF was given from days 0 to 27. Patient median age was 57 (range, 20 to 74) years. The cumulative incidences (CI) of day 100 grade II to IV and III to IV acute GVHD were 27% and 4%, respectively. With median follow-up of 10.3 (range, 3.1 to 14.5) years, the 5-year CI of chronic extensive GVHD was 48%. One-year and 5-year estimates of nonrelapse mortality, relapse/progression, survival, and progression-free survival were 9% and 13%, 35% and 50%, 73% and 53%, and 56% and 37%, respectively. GVHD prophylaxis with tacrolimus/MMF resulted in a low risk of acute GVHD and compared favorably with results from a concurrent trial using CSP/MMF. A randomized phase III trial to investigate tacrolimus/MMF versus CSP/MMF in nonmyeloablative HCT is warranted.

History of hematopoietic cell transplantation: challenges and progress

After more than 60 years of research in allogeneic hematopoietic cell transplantation (HCT), this therapy has advanced from one that was declared dead in the 1960s to a standard treatment of otherwise fatal malignant and non-malignant blood diseases. To date, close to 1.5 million hematopoietic cell transplants have been performed in more than 1,500 transplantation centers worldwide. This review will highlight the enormous efforts by numerous investigators throughout the world who have brought the experimental field of HCT to clinical reality, examine ongoing challenges, and provide insights for the future.

Graft-versus-cancereffect and innovative approaches in thetreatment of refractory solid tumors

Background/aim

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been used for the treatment of various refractory solid tumors during the last two decades. After the demonstration of graft-versus-leukemia (GvL) effect in a leukemic murine model following allo-HSCT from other strains of mice, graft-versus-tumor (GvT) effect in a solid tumor after allo-HSCT has also been reported in a murine model in 1984. Several trials have reported the presence of a GvT effect in patients with various refractory solid tumors, including renal, ovarian and colon cancers, as well as soft tissue sarcomas [1]. The growing data on haploidentical transplants also indicate GvT effect in some pediatric refractory solid tumors. Novel immunotherapy-based treatment modalities aim at inducing an allo-reactivity against the metastatic solid tumor via a GvT effect. Recipient derived immune effector cells (RDICs) in the antitumor reactivity following allo-HSCT have also been considered as an emerging therapy for advanced refractory solid tumors.

Conclusion

This review summarizes the background, rationale, and clinical results of immune-based strategies using GvT effect for the treatment of various metastatic and refractory solid tumors, as well as innovative approaches such as haploidentical HSCT, CAR-T cell therapies and tumor infiltrating lymphocytes (TIL).

Total marrow and total lymphoid irradiation in bone marrow transplantation for acute leukaemia

The use of total body irradiation as part of conditioning regimens for acute leukaemia is progressively declining because of concerns of late toxic effects and the introduction of radiation-free regimens. Total marrow irradiation and total marrow and lymphoid irradiation represent more targeted forms of radiotherapy compared with total body irradiation that have the potential to decrease toxicity and escalate the dose to the bone marrow for high-risk patients. We review the technological basis and the clinical development of total marrow irradiation and total marrow and lymphoid irradiation, highlighting both the possible advantages as well as the current roadblocks for widespread implementation among transplantation units. The exact role of total marrow irradiation or total marrow and lymphoid irradiation in new conditioning regimens seems dependent on its technological implementation, aiming to make the whole procedure less time consuming, more streamlined, and easier to integrate into the clinical workflow. We also foresee a role for computer-assisted planning, as a way to improve planning and delivery and to incorporate total marrow irradiation and total marrow and lymphoid irradiation in multi-centric phase 2-3 trials.

Allogeneic stem cell transplantation mitigates the adverse prognostic impact of high diagnostic BAALC and MN1 expression in AML

For most acute myeloid leukemia (AML) patients, an allogeneic hematopoietic stem cell transplantation (HSCT) offers the highest chance of sustained remissions and long-term survival. At diagnosis, high expression of the AML-associated genes BAALC (brain and acute leukemia, cytoplasmic) and MN1 (meningioma-1) were repeatedly linked to inferior outcomes in patients consolidated with chemotherapy while data for patients receiving HSCT remain limited. Using clinically applicable digital droplet PCR assays, we analyzed the diagnostic BAALC/ABL1 and MN1/ABL1 copy numbers in 302 AML patients. High BAALC/ABL1 and MN1/ABL1 copy numbers associated with common adverse prognostic factors at diagnosis. However, while high diagnostic copy numbers of both genes associated with shorter event free survival (EFS) and overall survival (OS) in patients receiving chemotherapy, there was no prognostic impact in patients undergoing HSCT. Our data suggests that the adverse prognostic impact of high BAALC and MN1 expression are mitigated by allogeneic HSCT. But preHSCT BAALC/ABL1 and MN1/ABL1 assessed in remission prior to HSCT remained prognosticators for EFS and OS independent of the diagnostic expression status. Whether allogeneic HSCT may improve survival for AML patients with high diagnostic BAALC or MN1 expression should be investigated prospectively and may improve informed decisions towards individualized consolidation options in AML.

Nonmyeloablative TLI-ATG conditioning for allogeneic transplantation: mature follow-up from a large single-center cohort

Nonmyeloablative total lymphoid irradiation and antithymocyte globulin (TLI-ATG) conditioning is protective against graft-versus-host disease (GVHD), while retaining graft-versus-tumor activity across various hematologic malignancies. We report our comprehensive experience using TLI-ATG conditioning in 612 patients with hematologic malignancies who underwent allogeneic transplantation at Stanford University from 2001 to 2016. All patients received granulocyte colony-stimulating factor-mobilized peripheral blood grafts and cyclosporine and mycophenolate mofetil for GVHD prophylaxis. The median age was 60 years (range, 21-78), with a median follow-up of 6.0 years (range, 1.0-16.4). Common diagnoses included acute myeloid leukemia (AML; n = 193), myelodysplastic syndrome (MDS; n = 94), chronic lymphocytic leukemia (CLL; n = 80), non-Hodgkin lymphoma (NHL; n = 175), and Hodgkin lymphoma (HL; n = 35). Thirty-four percent of patients had a comorbidity index ≥3, 30% had a high to very high disease risk index, and 56% received unrelated donor grafts, including 15% with HLA-mismatched donors. Ninety-eight percent underwent transplant in the outpatient setting, and 57% were never hospitalized from days 0 through 100. The 1-year rates of nonrelapse mortality (NRM), grade II-IV acute GVHD, and extensive chronic GVHD were 9%, 14%, and 22%, respectively. The 4-year estimates for overall and progression-free survival were 42% and 32% for AML, 30% and 21% for MDS, 67% and 43% for CLL, 68% and 45% for NHL, and 78% and 49% for HL. Mixed chimerism correlated with the risk of relapse. TLI-ATG conditioning was well tolerated, with low rates of GVHD and NRM. Durable remissions were observed across hematologic malignancies, with particularly favorable outcomes for heavily pretreated lymphomas. Several efforts are underway to augment donor chimerism and reduce relapse rates while maintaining the favorable safety and tolerability profile of this regimen.

Role of Stem-Cell Transplantation in Leukemia Treatment

Stem cells (SCs) play a major role in advanced fields of regenerative medicine and other research areas. They are involved in the regeneration of damaged tissue or cells, due to their self-renewal characteristics. Tissue or cells can be damaged through a variety of diseases, including hematologic and nonhematologic malignancies. In regard to this, stem-cell transplantation is a cellular therapeutic approach to restore those impaired cells, tissue, or organs. SCs have a therapeutic potential in the application of stem-cell transplantation. Research has been focused mainly on the application of hematopoietic SCs for transplantation. Cord blood cells and human leukocyte antigen-haploidentical donors are considered optional sources of hematopoietic stem-cell transplantation. On the other hand, pluripotent embryonic SCs and induced pluripotent SCs hold promise for advancement of stem-cell transplantation. In addition, nonhematopoietic mesenchymal SCs play their own significant role as a functional bone-marrow niche and in the management of graft-vs-host disease effects during the posttransplantation process. In this review, the role of different types of SCs is presented with regard to their application in SC transplantation. In addition to this, the therapeutic value of autologous and allogeneic hematopoietic stem-cell transplantation is assessed with respect to different types of leukemia. Highly advanced and progressive scientific research has focused on the application of stem-cell transplantation on specific leukemia types. We evaluated and compared the therapeutic potential of SC transplantation with various forms of leukemia. This review aimed to focus on the application of SCs in the treatment of leukemia.

Long-Term Disease Control After Allogeneic Hematopoietic Stem Cell Transplantation in Primary Cutaneous T-Cell Lymphoma; Results From a Single Institution Analysis

Background: Allogeneic hematopoietic stem cell transplantation (alloHSCT) has been proposed as curative approach for advanced cutaneous T–cell lymphomas (CTCL). Currently, there is no established consensus for the management of disease relapse after alloHSCT.

Results: Ten patients, previously treated with multiple lines of systemic treatment, received alloHSCT. Six patients had achieved partial response (PR, N = 5) and complete response (CR, N = 1) prior to HSCT. Post—HSCT, seven patients (N = 7) relapsed after a median time of 3.3 months (0.5–7.4 months) and were subsequently treated with radiotherapy (RT, N = 1), RT and adoptive T-cell transfer with EBV specific cells (N = 1), R-CHOP (N = 1) and interferon alpha−2a combined either with donor lymphocyte infusion (N = 1) or with brentuximab—vedotin (N = 1). One patient (N = 1) achieved PR only after reducing the immunosuppression. Two patients relapsed again and received interferon alpha−2a and brentuximab—vedotin, respectively. After a median follow-up time of 12.6 months (3.5–73.7 months) six patients were alive (60%) and four had deceased, three (N = 3) due to CTCL and one (N = 1) due to GVHD.

Conclusion: Disease relapse after alloHSCT can be controlled with available treatments. For most patients who ultimately relapsed, reduction of immunosuppression and interferon alpha−2a either administered alone or in combination with another systemic agent were preferred. Although interferon alpha−2a, similarly to immunosuppression reduction, may be beneficial for the achievement of graft–vs.–lymphoma effect, the risk of simultaneous worsening of GVHD must be carefully evaluated and taken into consideration.

Impact of Rituximab and Host/Donor Fc Receptor Polymorphisms after Allogeneic Hematopoietic Cell Transplantation for CD20+ B Cell Malignancies

We previously reported a 24% 1-year relapse rate in 93 older or medically unfit patients with CD20⁺ B cell malignancies after allogeneic hematopoietic cell transplantation (HCT) with low-intensity conditioning. The current prospective study tested the hypothesis that disease relapse could be reduced and overall survival (OS) improved by peritransplantation administration of rituximab (RTX). Sixty-three patients received RTX (375 mg/m²/day) on days -3, +10, +24, and +38 along with 2 to 3 Gy total body irradiation with or without fludarabine (30 mg/m² for 3 days). Median RTX levels of >25 μg/mL were achieved through day +84 after transplantation, but RTX level was not correlated with relapse or graft-versus-host disease (GVHD). HCT recipients with F/F and V/F FCγRIIIa polymorphisms showed a trend toward a higher relapse rate compared with those with V/V polymorphism (P= .15). No difference in outcome was found based on V/V donor pairing. Five-year relapse rates were similar between RTX-treated patients and historical controls (32% versus 28%; P = .94). RTX-treated patients had greater 5-year OS (47% versus 38%; P = .13) and progression-free survival (41% versus 32%; P = .12) compared with historical controls who underwent HCT without RTX, although the difference was not statistically significant. The incidence of acute GVHD was similar in the 2 groups (grade II-IV, 57% versus 56%; grade III-IV, 13% versus 17%), but the 5-year incidence of chronic GVHD was higher among RTX-treated patients (62% versus 47%). In patients with relapsed or refractory non-Hodgkin lymphoma, peritransplantation RTX neither reduced relapse nor improved GVHD. The role of donor-recipient pairing by FCγRIIIa polymorphisms in outcomes remains to be determined.

The FLAMSA concept-past and future

The FLAMSA reduced intensity (RIC) concept, also known as "sequential therapy", is a conceptual platform for the treatment of leukemia separated in several parts: induction therapy, a sequence of antileukemic and immunosuppressive conditioning for allogeneic stem cell transplantation, and immune restitution supported by donor lymphocyte transfusions. The antileukemic part consists of fludarabine, cytosine arabinoside, and amsacrine (FLAMSA); non-cross reactive agents like fludarabine and amsacrine have been successfully used in cases of refractoriness and relapse. Immunosuppressive conditioning and transplantation follow after only 3 days of rest. This way, the toxicity of allogeneic transplantation could be reduced and the anti-leukemia effects by using allogeneic immune cells could be optimized. This review summarizes available data on efficacy and toxicity of this approach. Further, possible strategies for improvements are discussed in order to provide better chances for elderly and frail patients and patients with advanced and high-risk disease. Among others, several new agents are available that target molecular changes of leukemia for induction of remission and allow for bridging the time after transplantation until adoptive immunotherapy becomes safe and effective.

Developments and translational relevance for the canine haematopoietic cell transplantation preclinical model

The development of safe and reliable haematopoietic cell transplantation (HCT) protocols to treat human patients with malignant and non-malignant blood disorders was highly influenced by preclinical studies obtained in random-bred canines. The surmounted barriers included recognizing the crucial importance of histocompatibility matching, establishing long-term donor haematopoietic cell engraftment, preventing graft-vs-host disease and advancing effective conditioning and post-grafting immunosuppression protocols, all of which were evaluated in canines. Recent studies have applied the tolerance inducing potential of HCT to solid organ and vascularized composite tissue transplantation. Several advances in HCT and tolerance induction that were first developed in the canine preclinical model and subsequently applied to human patients are now being recruited into veterinary practice for the treatment of malignant and non-malignant disorders in companion dogs. Here, we review recent HCT advancements attained in the canine model during the past 15 years.

Improved access to better HLA-matched hematopoietic cells for allogeneic transplant: analysis of donors and cord blood units selected for Canadian patients in 2018

BACKGROUND

Patients undergoing hematopoietic cell transplantation (HCT) often require use of an unrelated donor or cord blood unit (CBU). An understanding of evolving practices in graft selection is needed for optimization of donor recruitment and cord blood collection.

STUDY DESIGN AND METHODS

Each donor workup (WU) requested in 2018 involving a Canadian (CDN) patient and unique donor product or CBU was reviewed (n = 598). Degree of HLA match; product origin (domestic or international [INT]); and non-HLA factors including donor age, sex, cytomegalovirus (CMV), and ABO compatibility were analyzed for WUs that proceeded to transplant (n = 414). We also analyzed changes compared to a similar analysis performed in 2013.

RESULTS

The majority of transplants used matched unrelated donors (MUDs; n = 323; 78%) and were most often young (≤35 years), male, INT donors (n = 136). The proportion of transplants involving MUDs, as opposed to mismatched unrelated donors or CBUs, increased by 12.4% compared with 2013. When young, male, CDN MUDs were identified in patient search reports but not selected, CMV mismatching and ABO incompatibility were most likely to have influenced the decision to use an INT MUD. Consistent with global trends, CBU transplants decreased compared to 2013; however, the degree of HLA matching improved significantly, and 27% of transplanted CBUs were procured from the Canadian Blood Services Cord Blood Bank.

CONCLUSIONS

Access to MUDs and better HLA-matched CBUs by CDN patients has increased since 2013. Ongoing recruitment of young registrants and cord blood donors with diverse HLA haplotypes will support selection of donors with optimal non-HLA characteristics.

Population pharmacokinetics and Bayesian estimators for intravenous mycophenolate mofetil in haematopoietic stem cell transplant patients

AIMS

Intravenous mycophenolate mofetil (IV MMF), a prodrug of mycophenolic acid (MPA), is used during nonmyeloablative and reduced-intensity conditioning haematopoetic stem cell transplantation (HCT) to improve engraftment and reduce graft-versus-host disease. The aims of this study were to develop population pharmacokinetic models and Bayesian estimators based on limited sampling strategies to allow for individual dose adjustment of intravenous mycophenolate mofetil administered by infusion in haematopoietic stem cell transplant patients.

METHODS

Sixty-three MPA concentration-time profiles (median [min-max] = 6 [4-7] samples) were collected from 34 HCT recipients transplanted for 14 (1-45) days and administered IV MMF every 8 hours, concomitantly with cyclosporine. The database was split into development (75%) and validation (25%) datasets. Pharmacokinetic models characterized by a single compartment with first-order elimination, combined with two gamma distributions to describe the transformation of MMF into mycophenolic acid, were developed using in parallel nonparametric (Pmetrics) and parametric (ITSIM) approaches. The performances of the models and the derived Bayesian estimators were evaluated in the validation set.

RESULTS

The best limited sampling strategy led to a bias (min, max), root mean square error between observed and modeled interdose areas under the curve in the validation dataset of -11.72% (-31.08%, 5.00%), 14.9% for ITSIM and -2.21% (-23.40%, 30.01%), 12.4% for Pmetrics with three samples collected at 0.33, 2 and 3 hours post dosing.

CONCLUSION

Population pharmacokinetic models and Bayesian estimators for IV MMF in HCT have been developed and are now available online (https://pharmaco.chu-limoges.fr) for individual dose adjustment based on the interdose area under the curve.

Prophylaxis and management of graft versus host disease after stem-cell transplantation for haematological malignancies: updated consensus recommendations of the European Society for Blood and Marrow Transplantation

Graft-versus-host disease (GVHD) is a major factor contributing to mortality and morbidity after allogeneic stem-cell transplantation. Because of the small number of results from well designed, large-scale, clinical studies there is considerable variability in the prevention and treatment of GVHD worldwide. In 2014, to standardise treatment approaches the European Society of Blood and Marrow Transplantation published recommendations on the management of GVHD in the setting of HLA-identical sibling or unrelated donor transplantation in adult patients with haematological malignancies. Here we update these recommendations including the results of study published after 2014. Evidence was searched in three steps: first, a widespread scan of published trials, meta-analyses, and systematic reviews; second, expert opinion was added for specific issues following several rounds of debate; and third, a refined search to target debated or rapidly updating issues. On the basis of this evidence and the 2014 recommendations, five members of the EBMT Transplant Complications Working Party created 38 statements on GVHD prophylaxis, drug management, and treatment of acute and chronic GVHD. Subsequently, they created the EBMT GVHD management recommendation expert panel by recruiting 20 experts with expertise in GVHD management. An email-based, two-round Delphi panel approach was used to manage the consensus. Modified National Comprehensive Cancer Network categories for evidence and consensus were applied to the approved statements. We reached 100% consensus for 29 recommendations and 95% consensus for nine recommendations. Key updates to these recommendations include a broader use of rabbit anti-T-cell globulin; lower steroid doses for the management of grade 2 acute GVHD with isolated skin or upper gastrointestinal tract manifestations; fluticasone, azithromycin, and montelukast should be used for bronchiolitis obliterans syndrome; and the addition of newer treatment options for resteroid-refractory acute and chronic GVHD. In addition, we discuss specific aspects of GVHD prophylaxis and management in the setting of haploidentical transplantation and in paediatric patients, but no formal recommendations on those procedures have been provided in this Review. The European Society of Blood and Marrow Transplantation proposes to use these recommendations as a basis for the routine management of GVHD during stem-cell transplantation.

Is there an optimal conditioning for older patients with AML receiving allogeneic hematopoietic cell transplantation?

The optimal conditioning regimen for older patients with acute myeloid leukemia (AML) remains unclear. In this study, we compared outcomes of AML patients >60 years of age undergoing allogenic hematopoietic stem cell transplantation at our institution. All 404 consecutively treated patients received 1 of the following conditioning regimens: (1) fludarabine+melphalan 100 mg/m2 (FM100), (2) fludarabine+melphalan 140 mg/m2 (FM140), (3) fludarabine+IV busulfan AUC ≥ 5000/d × 4 d (Bu≥20000), and (4) fludarabine+IV busulfan AUC 4000/d × 4 d (Bu16000). A propensity score analysis (PSA) was used to compare outcomes between these 4 groups. Among the 4 conditioning regimens, the FM100 group had a significantly better long-term survival with 5-year progression-free survival of 49% vs 30%, 34%, and 23%, respectively. The benefit of the FM100 regimen resulted primarily from the lower nonrelapse mortality associated with this regimen, an effect more pronounced in patients with lower performance status. The PSA confirmed that FM100 was associated with better posttransplantation survival, whereas no significant differences were seen between the other regimen groups. In summary, older patients with AML benefited from a reduced-intensity conditioning regimen with lower melphalan doses (FM100), which was associated with better survival, even though it was primarily used in patients who could not receive a more intense conditioning regimen.

Targeting NAD immunometabolism limits severe graft-versus-host disease and has potent antileukemic activity

Acute graft-versus-host disease (aGVHD) and tumor relapse remain major complications after allogeneic hematopoietic stem cell transplantation. Alloreactive T cells and cancer cells share a similar metabolic phenotype to meet the bioenergetic demands necessary for cellular proliferation and effector functions. Nicotinamide adenine dinucleotide (NAD) is an essential co-factor in energy metabolism and is constantly replenished by nicotinamide phosphoribosyl-transferase (Nampt), the rate-limiting enzyme in the NAD salvage pathway. Here we show, that Nampt blockage strongly ameliorates aGVHD and limits leukemic expansion. Nampt was highly elevated in serum of patients with gastrointestinal GVHD and was particularly abundant in human and mouse intestinal T cells. Therapeutic application of the Nampt small-molecule inhibitor, Fk866, strongly attenuated experimental GVHD and caused NAD depletion in T-cell subsets, which displayed differential susceptibility to NAD shortage. Fk866 robustly inhibited expansion of alloreactive but not memory T cells and promoted FoxP3-mediated lineage stability in regulatory T cells. Furthermore, Fk866 strongly reduced the tumor burden in mouse leukemia and graft-versus-leukemia models. Ex vivo studies using lymphocytes from GVHD patients demonstrated potent antiproliferative properties of Fk866, suggesting potential clinical utility. Thus, targeting NAD immunometabolism represents a novel approach to selectively inhibit alloreactive T cells during aGVHD with additional antileukemic efficacy.

Outcomes of Allogeneic Stem Cell Transplant for Elderly Patients with Hematologic Malignancies

Reduced-intensity conditioning (RIC) regimens, improved HLA matching, and better supportive care allow allogeneic stem cell transplant (alloSCT) to be offered to older patients. Only a small percentage of eligible patients between ages 65 and 74 years actually undergo alloSCT, and comprehensive outcome data from the aging population are still lacking. We examined the outcome of older patients who underwent alloSCT using melphalan-based RIC for hematologic malignancies at our institution. We identified 125 patients older than 65 years (median, 69; range, 66 to 77) who underwent matched related donor, matched unrelated donor, or combined haploidentical/umbilical cord alloSCT between 2012 through November, 2017. Among them, 52 (41.6%) and 70 (56%) had, respectively, intermediate and high/very high Center for International Blood and Marrow Transplant Research (CIBMTR) disease risk index (DRI). One hundred six patients (85%) received fludarabine/melphalan-based RIC regimen with either antithymocyte globulin (ATG) or alemtuzumab. The median time to neutrophil engraftment was 13 days (range, 8 to 37) and platelet engraftment 17 days (range, 9 to 169). The cumulative incidence of nonrelapse mortality was 11.5% at 100 days and 30.1% and 34.8% at 1 and 2 years, respectively. The cumulative incidence of relapse was 35% and 40% at 1 and 2 years. The cumulative incidence of grades II to IV acute graft-versus-host disease (GVHD) at day 100 and 6 months was 29.5% and 34.5%, and chronic GVHD at 6, 12, and 24 months was 2.5%, 5.2%, and 6.3%, respectively. With a median follow-up of 32 months, the 1-, 2-, and 3-year progression-free survival (PFS) was 34.6%, 24.4%, and 16.5%, respectively. The graft GVHD-free survival was 24.6%, 16.1%, and 9.3%, respectively. The 1-, 2-, and 3-year overall survival (OS) was 44.5%, 30.7%, and 26.5%, respectively. In multivariable analysis, low albumin was predictive of poor PFS and OS and high hematopoietic cell transplantation-specific comorbidity index, and CIBMTR DRI was predictive of worse graft GVHD-free survival. Among long-term survivors the median Karnofsky performance status was 80. Older patients, even when referred with advanced disease, can benefit from melphalan-based alloSCT with HLA-matched or alternative donor sources without discernible impact of donor source on outcome. Using alemtuzumab- or ATG-based in vivo T cell depletion, the incidence of chronic GVHD is extremely low. Performance status in survivors is excellent. Better predictors for outcome in this patient population need to be identified.

Comparison of non-myeloablative and reduced-intensity allogeneic stem cell transplantation in older patients with myelodysplastic syndromes

Allogeneic stem cell transplantation (HSCT) remains the only curative treatment for myelodysplastic syndromes (MDS) or myelodysplastic/myeloproliferative neoplasms (MDS/MPN) patients. The introduction of reduced intensity (RIC) and non-myeloablative (NMA) conditioning enabled HSCT in older or comorbid individuals representing the majority of patients. Studies comparing RIC and NMA conditioning are limited. We retrospectively analyzed 151 MDS or MDS/MPN patients older than 50 years who received NMA- or RIC-HSCT. Patients younger or older than 65 years at HSCT were analyzed separately. Patients receiving RIC-HSCT or NMA-HSCT were balanced in factors reflecting disease aggressiveness and the HCT-CI comorbidity score. The NMA conditioned patients had a higher incidence of graft rejection and chronic graft-vs-host disease. Cumulative incidence of relapse (CIR), non-relapse mortality (NRM) and overall survival (OS), did not differ significantly with regard to the conditioning regime in the whole cohort. In patients <65 years at HSCT, NMA conditioning associated with higher NRM and shorter OS by trend, while CIR was similar in both groups. In multivariable analyzes, the conditioning regimen remained a prognostic factor for NRM and OS in patients <65 years at HSCT. In MDS patients NMA and RIC conditioning result in similar disease control, but especially patients <65 years may benefit from RIC-HSCT.

Fludarabine/busulfan versus fludarabine/total-body-irradiation (2 Gy) as conditioning prior to allogeneic stem cell transplantation in patients (≥60 years) with acute myelogenous leukemia: a study of the acute leukemia working party of the EBMT

Nonmyeloablative (NMA) conditioning regimens facilitate allogeneic stem cell transplantation (alloSCT) in elderly patients and/or in those with comorbidities. The acute leukemia working party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT) compared the outcomes of patients ≥60 years with AML in first complete remission (CR1), that had received an alloSCT following NMA conditioning, i.e. either fludarabine/busulfan (FB2) or fludarabine/total-body-irradiation-2Gy (FluTBI2Gy). A total of 1088 patients were included (median age 65 years). Donors were matched siblings (MSD) and matched unrelated donors (MUD) in 47% and 53%, respectively. In vivo T-cell depletion (TCD) was applied to 79% and none (0%) of patients in the FB2 and FluTBI2Gy groups, respectively. In the MSD group we found a trend for less extensive cGVHD in patients receiving FB2 with in vivo TCD, HR: 0.49, p = 0.08, and in those without worse NRM, HR: 2.14, p = 0.04, and a trend for more total cGVHD, HR: 1.61, p = 0.09. Patients transplanted from MUDs had a significantly higher incidence of total cGVHD, extensive cGVHD and a worse GRFS with FluTBI2Gy in comparison to FB2, HR: 2.44; p < 0.0001; HR 4.59; p < 0.00001 and HR: 1.35; p = 0.03, respectively. No differences were observed with respect to LFS, OS, RI, NRM, and aGVHD.

National survey on total-body irradiation prior to reduced-intensity stem cell transplantation in Japan: The Japanese Radiation Oncology Study Group

Reduced-intensity stem cell transplantation (RIST) minimizes the adverse effects of traditional hematopoietic stem cell transplantation, and low-dose total-body irradiation (TBI) is administered over a short period prior to RIST (TBI-RIST). Different institutes adopt different approaches for the administration of TBI-RIST, and since no study had previously investigated this issue, a survey of the TBI schedules in Japan was conducted. In October 2015, the Japanese Radiation Oncology Study Group initiated a national survey of TBI-RIST procedures conducted between 2010 and 2014. Of 186 institutions performing TBI, 90 (48%) responded to the survey, 78 of which performed TBI-RIST. Of 2488 patients who underwent TBI for malignant disease at these institutions, 1412 (56.8%) patients were treated for leukemia, 477 (19.2%) for malignant lymphoma, 453 (18.2) for myelodysplastic syndrome, 44 (1.8%) for multiple myeloma, and 102 (4.1%) for other malignant diseases. Further, 206 (52.0%) of 396 patients (a high proportion of patients) who underwent TBI for benign disease had aplastic anemia. The TBI-RIST equipment and treatment methods were similar to those used for myeloablative regimens. Routinely shielded organs included the lungs (43.6%), eyes (50.0%) and kidneys (10.2%). The ovaries (14.1%), thyroid (6.4%) and testicles (16.7%) were also frequently shielded, possibly reflecting an emphasis on shielding reproductive organs in children. TBI-RIST was performed more frequently than myeloablative conditioning in patients with benign disease. Genital and thyroid shielding were applied more frequently in patients treated with TBI-RIST than in patients treated with myeloablative conditioning. In conclusion, this study indicates the status of TBI-RIST in Japan and can assist future efforts to standardize TBI-RIST treatment methods and to design a future multicenter collaborative research study.

Yttrium-90-labeled anti-CD45 antibody followed by a reduced-intensity hematopoietic cell transplantation for patients with relapsed/refractory leukemia or myelodysplasia

Outcomes of patients with persistent high-risk leukemia or myelodysplasia prior to allogeneic hematopoietic cell transplantation are dismal. We therefore conducted a phase I trial evaluating the use of CD45-targeted radiotherapy preceding hematopoietic cell transplantation with the goal of improving outcomes for this high-risk scenario. Fifteen patients, median age 62 (range 37-76) years, were treated: ten with advanced acute myeloid leukemia, five with high-risk myelodysplastic syndrome. All patients had evidence of disease prior to treatment including nine with marrow blast counts ranging from 7-84% and six with minimal residual disease. Patients received escalating doses of yttrium-90-labeled anti-CD45 antibody followed by fludarabine and 2 Gy total body irradiation prior to human leukocyte antigen-matched, related or unrelated hematopoietic cell transplantation. Although a maximum dose of 30 Gy was delivered to the liver, no dose-limiting toxicity was observed. Therefore, the maximum-tolerated dose could not be estimated. Treatment led to complete remission in 13 patients (87%). All patients engrafted by day 28. Six patients relapsed, median of 59 (range 6-351) days, after transplantation. The 1-year estimate of relapse was 41%. Eight patients (53%) are surviving with median follow up of 1.8 (range 0.9-5.9) years. Estimated overall survival at one and two years was 66% and 46%, respectively, with progression-free survival estimated to be 46% at each time point. In conclusion, the combination of ⁹⁰Y-DOTA-BC8 with an allogeneic hematopoietic cell transplantation regimen was feasible and tolerable. This approach appears promising in this high-risk leukemia/myelodysplasia patient population with active disease. (Trial registered at clinicaltrials.gov identifier: NCT01300572.)

Antibody Therapies for Acute Myeloid Leukemia: Unconjugated, Toxin-Conjugated, Radio-Conjugated and Multivalent Formats

In recent decades, therapy for acute myeloid leukemia (AML) has remained relatively unchanged, with chemotherapy regimens primarily consisting of an induction regimen based on a daunorubicin and cytarabine backbone, followed by consolidation chemotherapy. Patients who are relapsed or refractory can be treated with allogeneic hematopoietic stem-cell transplantation with modest benefits to event-free and overall survival. Other modalities of immunotherapy include antibody therapies, which hold considerable promise and can be categorized into unconjugated classical antibodies, multivalent recombinant antibodies (bi-, tri- and quad-specific), toxin-conjugated antibodies and radio-conjugated antibodies. While unconjugated antibodies can facilitate Natural Killer (NK) cell antibody-dependent cell-mediated cytotoxicity (ADCC), bi- and tri-specific antibodies can engage either NK cells or T-cells to redirect cytotoxicity against AML targets in a highly efficient manner, similarly to classic ADCC. Finally, toxin-conjugated and radio-conjugated antibodies can increase the potency of antibody therapies. Several AML tumour-associated antigens are at the forefront of targeted therapy development, which include CD33, CD123, CD13, CLL-1 and CD38 and which may be present on both AML blasts and leukemic stem cells. This review focused on antibody therapies for AML, including pre-clinical studies of these agents and those that are either entering or have been tested in early phase clinical trials. Antibodies for checkpoint inhibition and microenvironment targeting in AML were excluded from this review.

Allogeneic Hematopoietic Cell Transplantation in the Outpatient Setting

Conditioning with fludarabine and low-dose total-body irradiation before allogeneic hematopoietic cell transplantation (HCT) enabled treating older or medically infirm patients with advanced hematologic malignancies in the outpatient setting. Between December 1997 and June 2017, 1037 patients with hematologic malignancies received peripheral blood stem cell (PBSC) grafts from HLA-matched or 1 HLA antigen/allele-mismatched related or unrelated donors. Median age was 58 (range, 18 to 80) years. Serious comorbidities with Hematopoietic Cell Transplantation-Specific Comorbidity Index (HCT-CI) scores ≥3 were present in 52% of patients. We found that 47% of patients were either never hospitalized or only had an overnight hospital stay for infusion of late-arriving PBSCs while 53% were admitted for a median of 6 days. Main reasons for admission were infection, fever, graft-versus-host disease, and regimen-related toxicity. Two thirds of admissions occurred within 3 weeks of HCT. The 5-year risk of nonrelapse mortality (NRM) was 26% among hospitalized patients and 13% among nonhospitalized patients. Significant risk factors for hospitalization included unrelated transplants, 1 HLA antigen-mismatched transplant, high HCT-CI scores, and diagnosis of nonmyeloma malignancies. Significant risk factors for NRM were hospitalization, older age, unrelated transplants, and high HCT-CI scores. Ambulatory allogeneic HCT is feasible and safe.

Addition of sirolimus to standard cyclosporine plus mycophenolate mofetil-based graft-versus-host disease prophylaxis for patients after unrelated non-myeloablative haemopoietic stem cell transplantation: a multicentre, randomised, phase 3 trial

BACKGROUND

Acute graft-versus-host-disease (GVHD) after non-myeloablative human leucocyte antigen (HLA)-matched, unrelated donor, allogeneic haemopoietic stem cell transplantation (HSCT) is associated with considerable morbidity and mortality. This trial aimed to evaluate the efficacy of adding sirolimus to the standard cyclosporine and mycophenolate mofetil prophylaxis therapy for preventing acute GVHD in this setting.

METHODS

This multicentre, randomised, phase 3 trial took place at nine HSCT centres based in the USA, Denmark, and Germany. Eligible patients were diagnosed with advanced haematological malignancies treatable by allogeneic HSCT, had a Karnofsky score greater than or equal to 60, were aged older than 50 years, or if they were aged 50 years or younger, were considered at high risk of regimen-related toxicity associated with a high-dose pre-transplantation conditioning regimen. Patients were randomly allocated by an adaptive randomisation scheme stratified by transplantation centre to receive either the standard GVHD prophylaxis regimen (cyclosporine and mycophenolate mofetil) or the triple-drug combination regimen (cyclosporine, mycophenolate mofetil, and sirolimus). Patients and physicians were not masked to treatment. All patients were prepared for HSCT with fludarabine (30 mg/m² per day) 4, 3, and 2 days before receiving 2 or 3 Gy total body irradiation on the day of HSCT (day 0). In both study groups, 5·0 mg/kg of cyclosporine was administered orally twice daily starting 3 days before HSCT, and (in the absence of GVHD) tapered from day 96 through to day 150. In the standard GVHD prophylaxis group, 15 mg/kg of mycophenolate mofetil was given orally three times daily from day 0 until day 30, then twice daily until day 150, and (in the absence of GVHD) tapered off by day 180. In the triple-drug group, mycophenolate mofetil doses were the same as in the standard group, but the drug was discontinued on day 40. Sirolimus was started 3 days before HSCT, taken orally at 2 mg once daily and adjusted to maintain trough concentrations between 3-12 ng/mL through to day 150, and (in the absence of GVHD) tapered off by day 180. The primary endpoint was the cumulative incidence of grade 2-4 acute GVHD at day 100 post-transplantation. Secondary endpoints were non-relapse mortality, overall survival, progression-free survival, cumulative incidence of grade 3-4 acute GVHD, and cumulative incidence of chronic GVHD. Efficacy and safety analyses were per protocol, including all patients who received conditioning treatment and underwent transplantation. Toxic effects were measured according to the Common Terminology Criteria for Adverse Events (CTCAE). The current study was closed prematurely by recommendation of the Data and Safety Monitoring Board on July 27, 2016, after 168 patients received the allocated intervention, based on the results of a prespecified interim analysis for futility. This study is registered with ClinicalTrials.gov, number NCT01231412.

FINDINGS

Participants were recruited between Nov 1, 2010, and July 27, 2016. Of 180 patients enrolled in the study, 167 received the complete study intervention and were included in safety and efficacy analyses: 77 patients in the standard GVHD prophylaxis group and 90 in the triple-drug group. At the time of analysis, median follow-up was 48 months (IQR 31-60). The cumulative incidence of grade 2-4 acute GVHD at day 100 was lower in the triple-drug group compared with the standard GVHD prophylaxis group (26% [95% CI 17-35] in the triple-drug group vs 52% [41-63] in the standard group; HR 0·45 [95% CI 0·28-0·73]; p=0·0013). After 1 and 4 years, non-relapse mortality increased to 4% (95% CI 0-9) and 16% (8-24) in the triple-drug group and 16% (8-24) and 32% (21-43) in the standard group (HR 0·48 [0·26-0·90]; p=0·021). Overall survival at 1 year was 86% (95% CI 78-93) in the triple-drug group and 70% in the standard group (60-80) and at 4 years it was 64% in the triple-drug group (54-75) and 46% in the standard group (34-57%; HR 0·62 [0·40-0·97]; p=0·035). Progression-free survival at 1 year was 77% (95% CI 68-85) in the triple-drug group and 64% (53-74) in the standard drug group, and at 4 years it was 59% in the triple-drug group (49-70) and 41% in the standard group (30-53%; HR 0·64 [0·42-0·99]; p=0·045). We observed no difference in the cumulative incidence of grade 3-4 acute GVHD (2% [0-5] in the triple-drug group vs 8% [2-14] in the standard group; HR 0·55 [0·16-1·96]; p=0·36) and chronic GVHD (49% [39-59] in triple-drug group vs 50% [39-61] in the standard group; HR 0·94 [0·62-1·40]; p=0·74). In both groups the most common CTCAE grade 4 or higher toxic effects were pulmonary.

INTERPRETATION

Adding sirolimus to cyclosporine and mycophenolate mofetil resulted in a significantly lower proportion of patients developing acute GVHD compared with patients treated with cyclosporine and mycophenolate mofetil alone. Based on these results, the combination of cyclosporine, mycophenolate mofetil, and sirolimus has become the new standard GVHD prophylaxis regimen for patients treated with non-myeloablative conditioning and HLA-matched unrelated HSCT at the Fred Hutchinson Cancer Research Center.

FUNDING

National Institutes of Health.

A Phase II Multicenter Study of the Addition of Azacitidine to Reduced-Intensity Conditioning Allogeneic Transplant for High-Risk Myelodysplasia (and Older Patients with Acute Myeloid Leukemia): Results of CALGB 100801 (Alliance)

Relapse remains the major cause of death in older patients transplanted for acute myeloid leukemia (AML) in first complete remission or for patients with advanced myelodysplastic syndrome (MDS) at any age. Conventional myeloablative conditioning followed by allogeneic blood or marrow transplantation is associated with significantly less relapse compared with reduced-intensity conditioning when performed in younger patients with AML or MDS, but the toxicity of this approach in older patients is prohibitive. We hypothesized that pharmacokinetic targeting to optimize busulfan (BU) exposure, combined with the administration of azacitidine (AZA) post-transplant would mitigate the risk of relapse while reducing nonrelapse mortality and ultimately improve progression-free survival (PFS). On this phase II multicenter study, 63 patients (40 unrelated donors and 23 matched related donors) received a uniform conditioning regimen consisting of fludarabine i.v. (days -7 to -3), BU targeted to a daily area under the curve (AUC) of 4000 μM/min (days -6 to -3) after the administration of a 25-mg/m² i.v. test dose on 1 day between days -14 to -9, and antithymocyte globulin (days -6, -5, and -4 (2 doses for matched related donors and 3 for matched unrelated donors only). Beginning on days +42 to +90, all patients were planned to receive up to 6 monthly cycles of AZA at 32 mg/m² subcutaneously for 5 days. The median age was 62 years (range, 44 to 74); 13 had AML and 50 had MDS; 87% of patients were within 20% of the target AUC based on a validation sample. Forty-one patients (65%) started AZA at a median of 61 days (range, 43 to 91) post-transplant, and 17 patients (41%) completed all 6 cycles of AZA. The cumulative incidence of nonrelapse mortality at 2 years was 33.4% (95% confidence interval [CI], 22%-45%). The cumulative incidence of relapse was 25% (95% CI, 15%-37%) at 2 years. With a median follow-up of 58.9 months, the estimated PFS probability at 2 years and 5 years after transplantation was 41.2% (80% CI, 33.9%-49.9%) and 26.9% (80% CI, 20.4%-35.5%), respectively, for the entire group with a median PFS of 15.8 months (95% CI, 6.7 to 28.3). The probability of overall survival at 2 and 5 years was 45.7% (95% CI, 34.9%-59.9%) and 31.2% (95% CI, 21.3% to 45.8%), respectively, for the entire group with a median overall survival of 19.2 months (95% CI, 8.7 to 37.5). In summary, we demonstrated the feasibility of a novel reduced-intensity conditioning regimen with test dose BU targeted to an AUC of 4000 μM/min. The feasibility of AZA in this setting appears to be limited if applied to an unselected population of older hematopoietic stem cell transplantation recipients. (ClinicalTrials.gov Identifier: NCT01168219.).

Inferior Outcomes with Cyclosporine and Mycophenolate Mofetil after Myeloablative Allogeneic Hematopoietic Cell Transplantation

Combination therapy with a calcineurin inhibitor (CNI), such as cyclosporine (CSA) or tacrolimus (Tac), and methotrexate (MTX) or mycophenolate mofetil (MMF) is a widely used approach to graft-versus-host disease (GVHD) prevention. Data on the comparative effectiveness of MMF compared with MTX are limited and conflicting, however. We analyzed data from the Center for International Blood and Marrow Transplant Research for adult patients undergoing first myeloablative hematopoietic cell transplantation (HCT) from an HLA-identical matched related donor (MRD; n = 3979) or matched unrelated donor (URD; n = 4163) using CSA+MMF, CSA+MTX, Tac+MMF, or Tac+MTX for GVHD prevention between 2000 and 2013. Within the MRD cohort, 2252 patients received CSA+MTX, 1391 received Tac+MTX, 114 received CSA+MMF, and 222 received Tac+MMF. Recipients of CSA+MMF had a higher incidence of acute GVHD grade II-IV (hazard ratio [HR], 1.65; 95% confidence interval [CI], 1.24 to 2.20; P < .001) and grade III-IV (HR, 1.92; 95% CI, 1.31 to 2.83; P < .001) compared with Tac+MTX. The use of CSA+MMF was also associated with inferior overall survival (OS) (HR, 2.31; 95% CI, 1.73 to 3.09; P < .001) due to higher transplantation-related mortality (TRM) (HR, 4.03; 95% CI, 2.61 to 6.23; P < .001) compared with Tac+MTX. Within the URD cohort, 974 patients received CSA+MTX, 2697 received Tac+MTX, 68 received CSA+MMF, and 424 received Tac+MMF. CSA+MMF was again significantly associated with a higher incidence of grade III-IV acute GVHD (HR, 2.31; 95% CI, 1.57 to 3.42; P <0001), worse OS (HR, 2.36; 95% CI, 1.67 to 3.35; P < .001), and higher TRM (HR, 3.09; 95% CI, 2.00 to 4.77; P < .001), compared with Tac+MTX and other regimens. Thus, this large retrospective comparison of MMF versus MTX in combination with CSA or Tac demonstrates significantly worse GVHD and survival outcomes with CSA+MMF compared with Tac+MTX.

Role of alternative donor allogeneic hematopoietic stem cell transplantation in patients with intermediate- or poor-risk acute myeloid leukemia in first complete remission

Allogeneic hematopoietic stem cell transplantation (HCT) offers the most effective prevention of relapse and has significant overall survival (OS) benefits for patients with acute myeloid leukemia (AML) in first complete remission (CR1). We conducted a retrospective analysis of a cohort of patients with intermediate- or poor-risk AML. The purpose of the present study was to investigate the role of alternative donors for AML in CR1. We analyzed 1561 patients who underwent HCT from an HLA-matched related donor (MRD), HLA 8/8-matched unrelated donor (MUD), or umbilical cord blood (UCB). The results of a multivariate analysis showed that HCT from UCB (HR = 1.28, 95% CI: 1.07-1.52), age ≥50 years (HR = 1.36, 95% CI: 1.14-1.62), male (HR = 1.42, 95% CI: 1.21-1.66), PS > 1 (HR = 1.68, 95% CI: 1.17-2.42), and poor-risk cytogenetics (HR = 1.53, 95% CI: 1.29-1.81) had an inferior prognostic impact on OS. We conclude that an MUD is the best alternative to an HLA identical MRD for patients with AML in CR1. UCB is an alternative option if neither MRD nor MUD are available, or when patients need to receive urgent HCT for poor-risk AML in CR1.