Posttransplant cyclophosphamide versus antithymocyte globulin in patients with acute lymphoblastic leukemia treated with allogeneic hematopoietic cell transplantation from matched unrelated donors: A study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation.

BACKGROUND: The aim of this study was to compare two immunosuppressive strategies, based on the use of either rabbit antithymocyte globulin (ATG) or posttransplant cyclophosphamide (PTCY), as a prophylaxis of graft-versus-host disease (GVHD) for patients with acute lymphoblastic leukemia (ALL) in first complete remission who underwent hematopoietic cells transplantation from matched unrelated donors. METHODS: Overall, 117 and 779 adult patients who received PTCY and ATG, respectively, between the years 2015 and 2020 were included in this retrospective study. The median patient age was 40 and 43 years in the PTCY and ATG groups, respectively, and 37% and 35% of patients, respectively, had Philadelphia chromosome-positive ALL. RESULTS: In univariate analysis, the cumulative incidence of acute and chronic GVHD did not differ significantly between the study groups. The cumulative incidence of relapse at 2 years was reduced in the PTCY group (18% vs. 25%; p = .046) without a significant impact on nonrelapse mortality (11% vs. 16% in the ATG group; p = .29). The rates of leukemia-free survival (LFS) and overall survival were 71% versus 59%, respectively (p = .01), and 82% versus 74%, respectively (p = .08). In multivariate analysis, the receipt of ATG compared with PTCY was associated with a reduced risk of extensive chronic GVHD (hazard ratio, 0.54; 95% confidence interval, 0.3-0.98; p = .04) and an increased risk of low LFS (hazard ratio, 1.57; 95% confidence interval, 1.01-2.45; p = .045). CONCLUSIONS: The receipt of ATG compared with PTCY, despite the reduced risk of extensive chronic GVHD, is associated with inferior LFS in adults with ALL who undergo hematopoietic cell transplantation from 10/10 human leukocyte antigen-matched unrelated donors. These findings warrant verification in prospective trials.

Relapsed or refractory large B-cell lymphoma after chimeric antigen receptor T-cell therapy: Current challenges and therapeutic options.

Chimeric antigen receptor (CAR) T-cell (CAR-T) therapy can provide durable remission in patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) after failure of chemoimmunotherapy. However, patients who are refractory or relapsing after CAR-T therapy have poor outcomes. Multiple mechanisms of CAR-T therapy failure have been proposed but management of these patients remains a challenge. As CAR-T therapy moves earlier in the treatment of DLBCL, we urgently need trials focused on patients with relapse after CAR-T therapy. Recent advances in novel immunotherapies such as bispecific antibodies, antibody-drug conjugates and next-generation CAR-T therapies may provide avenues for treatment. Here we review the available data on using these drugs after failure of CAR-T therapy and provide a framework for the ideal sequencing of these novel agents.

Impact of measurable residual disease on outcomes of unrelated donor haematopoietic cell transplantation with post-transplant cyclophosphamide in AML in first complete remission.

Pre-transplant measurable residual disease (MRD) predicts relapse and outcome of allogeneic haematopoietic cell transplantation (allo-HCT). The impact of MRD on the outcomes of post-transplant cyclophosphamide (PTCy)-based allo-HCT from a matched unrelated donor (UD) is unknown. This study assessed the impact of MRD in acute myeloid leukaemia (AML) in the first complete remission (CR1). A total of 272 patients (MRD negative [MRD-], n = 165; MRD positive [MRD+], n = 107) with a median follow-up of 19 (range: 16-24) months were studied. The incidence of grades II-IV and grades III-IV acute GVHD at day 180 was 25.2% and 25% (p = 0.99), and 10.6% and 6.8% (p = 0.29), respectively, and 2-year chronic GVHD was 35% and 30.4% (p = 0.96) in MRD+ and MRD- cohorts, respectively. In multivariate analysis, MRD+ status was associated with a higher incidence of relapse (RI) (hazard ratio [HR] = 2.56, 95% CI: 1.39-4.72), lower leukaemia-free survival (LFS) (HR = 2.04, 95% CI: 1.23-3.39), overall survival (OS) (HR = 1.83, 95% CI: 1.04-3.25) and GVHD-free, relapse-free survival (GRFS) (HR = 1.69, 95% CI: 1.10-2.58). MRD status did not have a significant impact on non-relapse mortality (NRM), or acute or chronic GVHD risk. Among patients with AML undergoing UD allo-HCT with PTCy, pre-transplant MRD+ status predicted a higher relapse rate, lower LFS, OS and GRFS.

Neighborhood poverty and pediatric allogeneic hematopoietic cell transplantation outcomes: a CIBMTR analysis.

Social determinants of health, including poverty, contribute significantly to health outcomes in the United States; however, their impact on pediatric hematopoietic cell transplantation (HCT) outcomes is poorly understood. We aimed to identify the association between neighborhood poverty and HCT outcomes for pediatric allogeneic HCT recipients in the Center for International Blood and Marrow Transplant Research database. We assembled 2 pediatric cohorts undergoing first allogeneic HCT from 2006 to 2015 at age ≤18 years, including 2053 children with malignant disease and 1696 children with nonmalignant disease. Neighborhood poverty exposure was defined a priori per the US Census definition as living in a high-poverty ZIP code (≥20% of persons below 100% federal poverty level) and used as the primary predictor in all analyses. Our primary outcome was overall survival (OS), defined as the time from HCT until death resulting from any cause. Secondary outcomes included relapse and transplantation-related mortality (TRM) in malignant disease, acute and chronic graft-versus-host disease, and infection in the first 100 days post-HCT. Among children undergoing transplantation for nonmalignant disease, neighborhood poverty was not associated with any HCT outcome. Among children undergoing transplantation for malignant disease, neighborhood poverty conferred an increased risk of TRM but was not associated with inferior OS or any other transplantation outcome. Among children with malignant disease, a key secondary finding was that children with Medicaid insurance experienced inferior OS and increased TRM compared with those with private insurance. These data suggest opportunities for future investigation of the effects of household-level poverty exposure on HCT outcomes in pediatric malignant disease to inform care delivery interventions.

Association between the choice of the conditioning regimen and outcomes of allogeneic hematopoietic cell transplantation for myelofibrosis.

Allogeneic hematopoietic cell transplantation (allo-HCT) remains the only curative treatment for myelofibrosis. However, the optimal conditioning regimen either with reduced-intensity conditioning (RIC) or myeloablative conditioning (MAC) is not well known. Using the Center for International Blood and Marrow Transplant Research database, we identified adults aged ≥18 years with myelofibrosis undergoing allo-HCT between 2008-2019 and analyzed the outcomes separately in the RIC and MAC cohorts based on the conditioning regimens used. Among 872 eligible patients, 493 underwent allo-HCT using RIC (fludarabine/ busulfan n=166, fludarabine/melphalan n=327) and 379 using MAC (fludarabine/busulfan n=247, busulfan/cyclophosphamide n=132). In multivariable analysis with RIC, fludarabine/melphalan was associated with inferior overall survival (hazard ratio [HR]=1.80; 95% confidenec interval [CI]: 1.15-2.81; P=0.009), higher early non-relapse mortality (HR=1.81; 95% CI: 1.12-2.91; P=0.01) and higher acute graft-versus-host disease (GvHD) (grade 2-4 HR=1.45; 95% CI: 1.03-2.03; P=0.03; grade 3-4 HR=2.21; 95%CI: 1.28-3.83; P=0.004) compared to fludarabine/busulfan. In the MAC setting, busulfan/cyclophosphamide was associated with a higher acute GvHD (grade 2-4 HR=2.33; 95% CI: 1.67-3.25; P<0.001; grade 3-4 HR=2.31; 95% CI: 1.52-3.52; P<0.001) and inferior GvHD-free relapse-free survival (GRFS) (HR=1.94; 95% CI: 1.49-2.53; P<0.001) as compared to fludarabine/busulfan. Hence, our study suggests that fludarabine/busulfan is associated with better outcomes in RIC (better overall survival, lower early non-relapse mortality, lower acute GvHD) and MAC (lower acute GvHD and better GRFS) in myelofibrosis.

Fludarabine versus cyclophospamide in combination with myeloablative total body irradiation as conditioning for patients with acute myeloid leukemia treated with allogeneic hematopoietic cell transplantation. A study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation.

Total body irradiation (TBI) at a dose of 12 Gy combined with cyclophosphamide (CyTBI12Gy) is one of the standard myeloablative regimens for patients with acute myeloid leukemia (AML) treated with allogeneic hematopoietic cell transplantation (allo-HCT). In clinical practice, cyclophosphamide may be substituted with fludarabine (FluTBI12Gy) to reduce toxicity. We retrospectively compared outcomes of CyTBI12Gy with FluTBI12Gy for patients with AML treated in complete remission (CR) with allo-HCT from either a matched sibling or unrelated donor. Of 1684 adults who met inclusion criteria, 109 patients in each group were included in a matched-pair analysis. The cumulative incidence of relapse at 2 years was 25% in the FluTBI12Gy compared to 28% in the CyTBI12Gy group (p = .44) while non-relapse mortality (NRM) was 17% versus 19%, (p = .89) respectively. The rates of leukemia-free survival and overall survival were 65% versus 54% (p = .28) and 70% versus 60.5% (p = .17). Cumulative incidence of grade 2-4 acute graft-versus-host disease (GVHD) was significantly lower for FluTBI12Gy than CyTBI12Gy (16% vs. 34%, p = .005), while the incidences of grade 3-4 acute GVHD and chronic GVHD did not differ significantly. The probability of GVHD and relapse-free survival was 49% in the FluTBI12Gy and 41% in the CyTBI12Gy group (p = .17). We conclude that for patients with AML treated with allo-HCT in CR, cyclophosphamide may be substituted with fludarabine in a regimen based on TBI at a dose of 12 Gy without negative impact on the efficacy. FluTBI12Gy is associated with reduced risk of grade 2-4 acute GVHD and encouraging survival rates.

Irradiation-free, T-cell replete haploidentical transplant for Fanconi anaemia, weighing the benefits.

The optimal haploidentical haematopoietic cell transplant approach for Fanconi anaemia (FA) patients is not well established, given the rarity of the disease, the increased sensitivity to DNA-damaging agents and the high risk of severe graft-versus-host disease (GVHD). The report by Xu et al. suggests that excellent engraftment and short-term survival can be achieved in FA patients without irradiation, but their retrospective cohort was plagued by a high rate of severe GVHD. Our commentary explores the outcomes in T-cell replete haploidentical haematopoietic cell transplant and ponders whether elimination of total body irradiation in FA patients is the best method if it limits the ability to safely administer post-transplant cyclophosphamide. Commentary on: Xu et al. Unmanipulated haploidentical haematopoietic cell transplantation with radiation-free conditioning in Fanconi anaemia: A retrospective analysis from the Chinese Blood and Marrow Transplantation Registry Group. Br J Haematol. 2022;199:401-410.

Promise and pitfalls of allogeneic chimeric antigen receptor therapy in plasma cell and lymphoid malignancies.

Chimeric antigen receptor (CAR) T-cell therapy is a promising immunotherapy in haematological malignancies. However, the currently approved products are generated from autologous T cells that require orchestration of several logistically complex steps, which include patient eligibility, apheresis capability, complex manufacturing processes and shipping logistics. Use of third-party donor-derived (allogeneic) effector cells that allows the generation of 'off-the-shelf" CAR T cells (allo-CAR) could circumvent many of the problems associated with autologous CAR T-cell therapy. Several allogeneic products are entering clinical trials, and though early, the results look promising. The recognised potential benefits of allo-CAR do not come without significant challenges, that must be overcome for their widespread use. Alloreactivity, i.e. graft-versus-host disease (GVHD), and rejection of donor T cells is one of the major barriers, while other potential barriers include immunogenicity, unknown in vivo persistence, and CAR T-cell yield. In the present review, we provide a comprehensive review of the challenges associated with autologous CAR, the benefits and potential challenges associated with allo-CAR. Finally, we review the available platforms for allo-CAR for B-cell and plasma cell malignancies.

Does recipient body mass index inform donor selection for allogeneic haematopoietic cell transplantation?

It is not known whether obesity has a differential effect on allogeneic haematopoietic cell transplantation outcomes with alternative donor types. We report the results of a retrospective registry study examining the effect of obesity [body mass index (BMI) > 30] on outcomes with alternative donors (haploidentical related donor with two or more mismatches and receiving post-transplant cyclophosphamide [haplo] and cord blood (CBU)] versus matched unrelated donor (MUD). Adult patients receiving haematopoietic cell transplantation for haematologic malignancy (2013-2017) (N = 16 182) using MUD (n = 11 801), haplo (n = 2894) and CBU (n = 1487) were included. The primary outcome was non-relapse mortality (NRM). The analysis demonstrated a significant, non-linear interaction between pretransplant BMI and the three donor groups for NRM: NRM risk was significantly higher with CBU compared to haplo at BMI 25-30 [hazard ratio (HR) 1.66-1.71, p < 0.05] and MUD transplants at a BMI of 25-45 (HR, 1.61-3.47, p < 0.05). The results demonstrated that NRM and survival outcomes are worse in overweight and obese transplant recipients (BMI ≥ 25) with one alternative donor type over MUD, although obesity does not appear to confer a uniform differential mortality risk with one donor type over the other. BMI may serve as a criterion for selecting a donor among the three (MUD, haplo and CBU) options, if matched sibling donor is not available.

Post-transplantation cyclophosphamide versus antithymocyte globulin in patients with acute myeloid leukemia undergoing allogeneic stem cell transplantation from HLA-identical sibling donors: A retrospective analysis from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation.

BACKGROUND: Graft-versus-host disease (GVHD) is a major complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Addition of antithymocyte globulin (ATG) or post-transplantation cyclophosphamide (PTCY) to standard immunosuppressive agents reduces GVHD in different donor settings. METHODS: We compared the outcomes of adults with acute myeloid leukemia undergoing allo-HSCT from HLA-identical sibling donors after the use of PTCY (n = 197) or ATG (n = 1913). RESULTS: Patients in the PTCY group were younger than those in the ATG group (median age, 47 vs 54 years; P < .01). Peripheral blood was the most frequently used stem cell source, being significantly more frequent in the ATG group than in the PTCY group (95% vs 70% P < .01). The conditioning regimen was more frequently myeloablative in the PTCY group than in the ATG group (59% vs 48%; P < .01). Time to neutrophil engraftment was shorter in the ATG group than in the PTCY group (17 vs 20 days; P < .01). No differences were observed according to the other transplantation outcomes, except for chronic GVHD of all grades and extensive chronic GVHD at 2 years, which were significantly lower in the ATG group compared with the PTCY group (P < .02). CONCLUSION: PTCY is feasible in an HLA-identical sibling setting, and despite similar outcomes, ATG may be associated with lower incidence of chronic GVHD.

Community health status and outcomes after allogeneic hematopoietic cell transplantation in the United States.

BACKGROUND: The association of community factors and outcomes after hematopoietic cell transplantation (HCT) has not been comprehensively described. Using the County Health Rankings and Roadmaps (CHRR) and the Center for International Blood and Marrow Transplant Research (CIBMTR), this study evaluated the impact of community health status on allogeneic HCT outcomes. METHODS: This study included 18,544 adult allogeneic HCT recipients reported to the CIBMTR by 170 US centers in 2014-2016. Sociodemographic, environmental, and community indicators were derived from the CHRR, an aggregate community risk score was created, and scores were assigned to each patient (patient community risk score [PCS]) and transplant center (center community risk score [CCS]). Higher scores indicated less healthy communities. The impact of PCS and CCS on patient outcomes after allogeneic HCT was studied. RESULTS: The median age was 55 years (range, 18-83 years). The median PCS was -0.21 (range, -1.37 to 2.10; standard deviation [SD], 0.42), and the median CCS was -0.13 (range, -1.04 to 0.96; SD, 0.40). In multivariable analyses, a higher PCS was associated with inferior survival (hazard ratio [HR] per 1 SD increase, 1.04; 99% CI, 1.00-1.08; P = .0089). Among hematologic malignancies, a tendency toward inferior survival was observed with a higher PCS (HR, 1.04; 99% CI, 1.00-1.08; P = .0102); a higher PCS was associated with higher nonrelapse mortality (NRM; HR, 1.08; 99% CI, 1.02-1.15; P = .0004). CCS was not significantly associated with survival, relapse, or NRM. CONCLUSIONS: Patients residing in counties with a worse community health status have inferior survival as a result of an increased risk of NRM after allogeneic HCT. There was no association between the community health status of the transplant center location and allogeneic HCT outcomes.

Taking a BiTE out of the CAR T space race.

Chimaeric antigen receptor T-cell (CAR T) therapy has evolved at an exponential pace and seeks to revolutionize the CAR T space with next-generation CARs and expanding indications in plasma cell dyscrasias. Recent developments in Bispecific T-cell engager therapy (BiTEs) may level the playing field with CAR T therapy, offering key advantages with off-the-shelf or on-demand treatment and a manageable toxicity profile to encompass a wider pool of eligible patients in the outpatient setting. The coexistence of both modalities will remain important in overall management and accelerate the next iteration of both cellular and BiTEs. This article summarises the current progress, potential future of both therapies for haematologic malignancies, and their economic implications on the healthcare system.

Graft-versus-host disease risk after chimeric antigen receptor T-cell therapy: the diametric opposition of T cells.

Chimeric antigen receptor (CAR) T-cell therapy has brought a paradigm shift in the management of haematological malignancies and has opened novel avenues of investigational therapeutic strategies. Given these encouraging responses, it has become imperative to understand the full spectrum of biology and potential toxicities that can arise from these novel agents, as well as those under investigation. With the increasing use of CAR T-cell therapy for relapse following allogeneic haematopoietic cell transplantation (HCT) and the imminence of allogeneic CAR T cells, risks from T cell-based therapy, such as the previously well-recognised graft-versus-host disease (GVHD), have gained prominence and warrant explanation. In the present review, we discuss the risk of GVHD in the: (1) post-HCT setting using recipient or donor-derived CAR T cells, as well as (2) non-HCT setting using autologous, as well as allogeneic T-cell therapies. A better understanding of this risk is important to advance the field and ensure safe development and use of these agents in the clinic.

Machine learning and artificial intelligence in haematology.

Digitalization of the medical record and integration of genomic methods into clinical practice have resulted in an unprecedented wealth of data. Machine learning is a subdomain of artificial intelligence that attempts to computationally extract meaningful insights from complex data structures. Applications of machine learning in haematological scenarios are steadily increasing. However, basic concepts are often unfamiliar to clinicians and investigators. The purpose of this review is to provide readers with tools to interpret and critically appraise machine learning literature. We begin with the elucidation of standard terminology and then review examples in haematology. Guidelines for designing and evaluating machine-learning studies are provided. Finally, we discuss limitations of the machine-learning approach.

The evolving role of allogeneic haematopoietic cell transplantation in the era of chimaeric antigen receptor T-cell therapy.

Chimaeric antigen receptor T-cell (CAR T) therapy has revolutionized the management of many haematological malignancies. It is associated with impressive disease responses in relapsed or refractory high-grade B-cell non-Hodgkin lymphoma (B-NHL) and acute lymphoblastic leukaemia (B-ALL) with durable remissions in a subset of patients. Historically, haematopoietic cell transplantation (HCT) has been the standard consolidation strategy for many of these patients who are now being treated with CAR T. Relapses are frequent after CD19 CAR T therapy in B-ALL and consolidation with allogeneic HCT (allo-HCT) may improve survival of patients with high-risk disease. There appears to be a clear difference in B-ALL outcomes between paediatric and adult patients, with the latter having a much higher risk of relapse after CAR T therapy. Late relapses are infrequent in patients with B-NHL and consolidation with allo-HCT may not be needed in patients who achieve a complete remission after CAR T therapy. Future registry-based and prospective studies will hopefully provide the needed data in the future to risk-stratify the recipients of CAR T therapy. Meanwhile, we provide guidance on patient selection and practical issues with performing allo-HCT after CAR T therapy.

Second allogeneic haematopoietic cell transplantation using HLA-matched unrelated versus T-cell replete haploidentical donor and survival in relapsed acute myeloid leukaemia.

Optimal donor choice for a second allogeneic haematopoietic cell transplant (allo-HCT) in relapsed acute myeloid leukaemia (AML) remains unknown. We compared overall survival (OS) using registry data from the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT) involving 455 adults who received a second allo-HCT from a human leucocyte antigen (HLA)-matched unrelated (MUD) (n = 320) or a haploidentical (n = 135) donor. Eligibility criteria required adults aged ≥18 years who received a second allo-HCT for treating AML relapse between 2005 and 2019. The primary end-point was OS. There was no statistically significant difference in the median (interquartile range) age between the groups, MUD 46 (35-58) versus haploidentical 44 (33-53) years (P = 0·07). The median OS was not different between the MUD and the haploidentical groups (10 vs. 11 months, P = 0·57). Similarly, the 2-year OS was 31% for the MUD and 29% for the haploidentical donor groups. The OS was worse if the procedure was performed with active AML [hazard ratio (HR) 1·42, 95% confidence interval (CI) 1·07-1·89; P = 0·02]. Conversely, a longer time from first allo-HCT to relapse (>13·2 months) was associated with better OS (HR 0·50, 95% CI 0·37-0·69; P < 0·0001). The results of the present analysis limit the ability to recommend one donor type over another when considering a second allo-HCT for relapsed AML. Our findings highlight that best OS is achieved when receiving the second allo-HCT in complete remission.

Post-transplant cyclophosphamide versus anti-thymocyte globulin for graft-versus-host disease prevention in haploidentical transplantation for adult acute lymphoblastic leukemia.

Graft-versus-host disease (GVHD) prophylaxis for unmanipulated haploidentical hematopoietic cell transplantation (haplo-HCT) include post-transplant cyclophosphamide (PTCy) and anti-thymocyte globulin (ATG). Utilizing EBMT registry, we compared ATG versus PTCy based GVHD prophylaxis in adult acute lymphoblastic leukemia (ALL) patients undergoing haplo-HCT. Included were 434 patients; ATG (n=98) and PTCy (n=336). Median follow-up was ~2 years. Baseline characteristics were similar between the groups except that the ATG-group was more likely to have relapsed/refractory ALL (P=0.008), non-TBI conditioning (P<0.001), peripheral blood graft source (P=<0.001) and transplanted at an earlier time-period (median year of HCT 2011 vs. 2015). The 100-day grade II-IV and III-IV acute-GVHD was similar between ATG and PTCy, as was 2-year chronic-GVHD. On multivariate analysis (MVA), leukemia-free survival (LFS) and overall survival (OS) was better with PTCy compared to ATG prophylaxis. Relapse incidence (RI) was lower in the PTCy group (P=0.03), while non-relapse mortality (NRM) was not different. Advanced disease and lower performance score were associated with poorer LFS and OS and advanced disease with inferior GVHD-free/relapse-free survival (GRFS). Peripheral grafts were associated with higher GVHD compared to bone marrow grafts. In ALL patients undergoing unmanipulated haplo-HCT, PTCy for GVHD prevention resulted in lower RI and improved LFS and OS compared to ATG.

Hematopoietic Cell Transplant Consideration for Philadelphia Chromosome-Like Acute Lymphoblastic Leukemia Patients.

Philadelphia chromosome-like (Ph-like) acute lymphoblastic leukemia (ALL) is a relatively new entity characterized by high cytokine receptor and tyrosine kinase signaling resulting in multiple downstream pathway stimulation. The standard diagnostic method, gene expression profiling, is not widely available. Efforts are ongoing to establish easy and clinically applicable diagnostic pathways to facilitate the accurate identification of these patients and thus enable a better understanding of the prognosis and outcomes with different treatment approaches. The rates of complete remission in ALL patients are consistently above 90% with the different induction protocols; however, maintaining remission depends on the risk group of the patient and consolidation therapy. Allogeneic hematopoietic cell transplant (allo-HCT) is particularly beneficial when the risk of relapse is very high and the expected complications with transplant are low. Data on the outcomes of allo-HCT for Ph-like ALL are scarce. In this article we review the published literature on outcomes of Ph-like ALL patients treated using different therapeutic approaches and make recommendations about transplant consideration for these patients.

FLAMSA-Based Reduced-Intensity Conditioning versus Myeloablative Conditioning in Younger Patients with Relapsed/Refractory Acute Myeloid Leukemia with Active Disease at the Time of Allogeneic Stem Cell Transplantation: An Analysis from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation.

The use of myeloablative conditioning (MAC) in the setting of active relapsed/refractory (R/R) acute myeloid leukemia (AML) has been hindered by high historical rates of nonrelapse mortality (NRM). FLAMSA (fludarabine, Ara-C, and amsacrine) chemotherapy (CT) followed by reduced-intensity conditioning (RIC) has been proposed as an effective and potentially safer alternative in this scenario. As improvements in supportive care have contributed to decreasing NRM rates after MAC, a comparative reassessment of these two strategies was performed. This was a registry-based analysis by the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation. Eligibility criteria included age 18 to 50 years, primary refractory, first or second relapsed active AML, first allogeneic stem cell transplantation from a matched sibling donor (MSD) or an unrelated donor (UD) performed between 2005 and 2018, MAC or FLAMSA-RIC. A total of 1018 patients were included. The median patient age was 39 years (range, 18 to 50). Two hundred and fifty-eight patients received busulfan (Bu)/cyclophosphamide (Cy), 314 received Cy/total body irradiation (TBI), 318 received FLAMSA-TBI, and 128 received FLAMSA-CT. The median duration of follow-up was 50 months. In univariate analysis, the 2-year relapse incidence (RI) (54%; 95% confidence interval (CI), 50%-57%), leukemia-free survival (LFS) (30%; 95% CI, 27%-33%), and refined graft-versus-host disease-free, relapse-free survival (GRFS) (21%; 95% CI, 18%-24%) were not significantly different between cohorts. Lower 2-year NRM was observed in the FLAMSA-CT group (7% versus 16% in Bu/Cy, 19% in Cy/TBI, and 18% in FLAMSA-TBI; P = .04), as well as increased 2-year overall survival (OS) (50% versus 33% in Bu/Cy, 34% in Cy/TBI, and 36% in FLAMSA-TBI; P = .03). These results were maintained in the multivariate analysis (hazard ratio [HR] for NRM: .40, P = .01; HR for OS: .65, P = .01; Bu/Cy as reference). These data suggest that FLAMSA-CT may be a preferred conditioning regimen in patients with active R/R AML due to lower NRM. Yet, the high relapse rates observed in our analyses emphasize the need for novel therapeutic strategies in this clinical setting.

Indications for Hematopoietic Cell Transplantation and Immune Effector Cell Therapy: Guidelines from the American Society for Transplantation and Cellular Therapy.

The American Society for Transplantation and Cellular Therapy (ASTCT) published its first white paper on indications for autologous and allogeneic hematopoietic cell transplantation (HCT) in 2015. It was identified at the time that periodic updates of indications would be required to stay abreast with state of the art and emerging indications and therapy. In recent years the field has not only seen an improvement in transplantation technology, thus widening the therapeutic scope of HCT, but additionally a whole new treatment strategy using modified immune effector cells, including chimeric antigen receptor T cells and engineered T-cell receptors, has emerged. The guidelines review committee of the ASTCT deemed it optimal to update the ASTCT recommendations for indications for HCT to include new data and to incorporate indications for immune effector cell therapy (IECT) where appropriate. The guidelines committee established a multiple stakeholder task force consisting of transplant experts, payer representatives, and a patient advocate to provide guidance on indications for HCT and IECT. This article presents the updated recommendations from the ASTCT on indications for HCT and IECT. Indications for HCT/IECT were categorized as (1) Standard of care, where indication is well defined and supported by evidence; (2) Standard of care, clinical evidence available, where large clinical trials and observational studies are not available but have been shown to be effective therapy; (3) Standard of care, rare indication, for rare diseases where demonstrated effectiveness exists but large clinical trials and observational studies are not feasible; (4) Developmental, for diseases where preclinical and/or early-phase clinical studies show HCT/IECT to be a promising treatment option; and (5) Not generally recommended, where available evidence does not support the routine use of HCT/IECT. The ASTCT will continue to periodically review these guidelines and update them as new evidence becomes available.