Risk score for outcome after allogeneic hematopoietic stem cell transplantation

Younger unrelated donors may be preferable over HLA match in the PTCy era: a study from the ALWP of the EBMT

ABSTRACT

There is a paucity of information on how to select the most appropriate unrelated donor (UD) in hematopoietic stem cell transplantation (HSCT) using posttransplant cyclophosphamide (PTCy). We retrospectively analyzed the characteristics of 10/10 matched UDs (MUDs) and 9/10 mismatched UDs (MMUDs) that may affect transplant outcomes in patients with acute myeloid leukemia (AML) in first or second complete remission (CR1 or CR2). The primary end point was leukemia-free survival (LFS). Overall, 1011 patients were included with a median age of 54 years (range, 18-77). Donors had a median age of 29 years (range, 18-64); 304 (30%) were females, of which 150 (15% of the whole group) were donors to male recipients, and 621 (61%) were MUDs; 522 (52%) had negative cytomegalovirus (CMV-neg) serostatus, of which 189 (19%) were used for CMV-neg recipients. Donor age older than 30 years had a negative impact on relapse (hazard ratio [HR], 1.38; 95% confidence interval [CI], 1.06-1.8), LFS (HR, 1.4; 95% CI, 1.12-1.74), overall survival (HR 1.45; 95% CI, 1.14-1.85) and graft-versus-host disease (GVHD) free, relapse-free survival (HR, 1.29; 95% CI, 1.07-1.56). In addition, CMV-neg donors for CMV-neg recipients were associated with improved LFS (HR, 0.74; 95% CI, 0.55-0.99). The use of MMUD and female donors for male recipients did not significantly impact any transplant outcomes. For patients undergoing HSCT from a UD with PTCy for AML, donor age <30 years significantly improves survival. In this context, donor age might be prioritized over HLA match considerations. In addition, CMV-neg donors are preferable for CMV-neg recipients. However, further research is needed to validate and refine these recommendations.

The role of registries in hematological disorders

Hematopoietic cell transplantation (HCT) was developed more than 65 years ago to treat malignant blood disorders and irreversible bone marrow failures, with the aim of replacing a diseased hematopoietic system with a healthy one (allogeneic HCT). Decades later, the procedure was adapted to apply maximal chemotherapy or radiotherapy, which would result in bone marrow failure, but could be remedied by an infusion of a patient's own cryopreserved bone marrow (autologous HCT). Both treatments are high-risk and complex, especially during the initial phases. However, concerted efforts, vision, and collaboration between physicians and centers worldwide have resulted in HCT becoming a standard of care for many hematological disorders with progressive improvements in outcomes. Registries and the collaboration of societies worldwide have enabled the delivery of this curative therapy to many patients with fatal hematological diseases. More than 1.5 million HCT were performed between 1957 and 2019, and activity is continuously increasing worldwide.

Prognostic factors in haploidentical transplantation with post-transplant cyclophosphamide for acute myeloid leukemia

BACKGROUND AIMS

Haploidentical hematopoietic stem cell transplantation (haplo-HCT) is an appropriate option when an HLA-matched related or unrelated donor is not available. Haplo-HCT using post-transplant cyclophosphamide (PTCy) is being increasingly performed worldwide due to its effective suppression of GVHD and its safety.

METHODS

We conducted a large nationwide cohort study to retrospectively analyze 366 patients with acute myeloid leukemia undergoing haplo-HCT with PTCy between 2010 and 2019 and to identify prognostic factors.

RESULTS

A multivariate Cox analysis revealed that an older recipient age (≥60 years), a male donor to a male recipient, a cytomegalovirus IgG-negative donor to a cytomegalovirus IgG-positive recipient, a poor cytogenetic risk, a noncomplete remission status at the time of transplantation, and a history of HCT were independently associated with worse overall survival (OS). Based on each hazard ratio, these factors were scored (1-2 points) and stratified by their total score into three groups: favorable (0-1 points), intermediate (2-3 points), and poor (4 points or more) groups, and 2-year OS rates were 79.9%, 49.2%, and 25.1%, respectively (P < 0.001).

CONCLUSIONS

The present study revealed significant prognostic factors in haplo-HCT with PTCy, and a scoring system based on these factors may be used to predict outcomes.

Comparison of valganciclovir versus foscarnet for the treatment of cytomegalovirus viremia in adult acute leukemia patients after allogeneic hematopoietic cell transplantation

Cytomegalovirus (CMV) reactivation increases treatment-related mortality (TRM) after allogeneic hematopoietic cell transplantation (allo-HCT). We analyzed 141 adult acute leukemia (AL) patients suffered allo-HCT between 2017 and 2021, who developed CMV viremia post-HCT and treated with valganciclovir or foscarnet, to evaluate effectiveness and safety of both drugs. Viremia clearance rates (14 and 21 d post treatment) and toxicities were similar in two groups. However, valganciclovir was associated with a lower cumulative incidence of CMV recurrence within 180 days (16.7% vs. 35.7%, p=0.029) post CMV clearance. Finally, 2-year TRM was lower in valganciclovir group (9.7% ± 0.2% vs. 26.2% ± 0.3%, p = 0.026), result a superior 2-year overall survival (OS; 88.1% ± 5.2% vs. 64.4% ± 5.5%, p = 0.005) and leukemia-free survival (LFS; 82.0% ± 5.9% vs. 58.9% ± 5.6%, p = 0.009). Valganciclovir might decrease CMV viremia recurrence and led to better long-term outcome than foscarnet in adult AL patients developed CMV viremia post-HCT. Considering the inherent biases of retrospective study, well-designed trials are warranted to validate our conclusion.

The impact of MICB mismatches in unrelated haematopoietic stem cell transplantation

MICA polymorphisms have been associated with increased incidence of acute GvHD and adverse outcome in allogeneic haematopoietic stem cell transplantation (HSCT). MICB is another expressed member of MHC class I-related chain genes and its impact on HSCT outcome is yet to be fully defined. We typed a large cohort of patients and donors for MICB polymorphisms and investigated the impact of MICB matching on outcome after unrelated HSCT. 69.2% of the patients were 10/10 human leukocyte antigen (HLA) matched and 30.8% were 9/10 HLA matched. MICB typing was performed using a short amplicon-based NGS typing assay on the Illumina MiSeq platform. Differences in proteins were considered as mismatches. MICA polymorphisms were identified as possible confounder and were therefore included as parameter in the multivariate analyses. Due to the strong linkage disequilibrium with the classical HLA-genes, sub-stratification for HLA matching status was necessary, and no effect of MICB mismatches was seen in the 10/10 HLA matched group when compared to the MICB matched cases. However, in the 9/10 HLA matched group, MICB mismatched cases showed significantly worse disease free survival (DFS), GvHD and relapse free survival (GRFS) compared to the MICB matched cases (DFS: HR 1.24, p = 0.011; GRFS: HR 1.26, p = 0.002). MICA mismatches had no impact on any outcome parameter. According to our findings, effects previously attributed to MICA differences may have been confounded by MICB polymorphisms. We show that MICB differences contribute a small but relevant effect in 9/10 HLA-matched transplantations, which in turn highlights the possible usefulness of MICB typing in donor selection among similarly suitable 9/10 matched donors, especially when HLA-B mismatches have to be accepted.

Haploidentical stem cell donor choice for patients with acute myeloid leukemia: a study from the ALWP of the EBMT

ABSTRACT

There is a paucity of information to guide the selection of the most suitable donor in haploidentical (Haplo) hematopoietic stem cell transplantation (HSCT). For this reason, from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, we conducted a retrospective analysis to evaluate the impact of Haplo donor characteristics on outcomes in patients with acute myeloid leukemia (AML) who received graft-versus-host disease prophylaxis with posttransplant cyclophosphamide (PTCy). The primary end point was graft-versus-host disease (GVHD)-free and relapse-free survival (GRFS). Overall, 2200 patients were included. The median age of donors was 37 years (range, 8-71); 820 (37%) were females, including 458 (21%) who were used for male recipients. In addition, 1631 donors (74%) donated peripheral blood (PB). Multivariable analysis identified certain donor-related risk factors with a detrimental impact on transplant outcomes. The use of PB, older donors' ages (>37 years), and female donors to male recipients negatively affected GRFS. Donor's age and female donor-to-male recipient combination also affected nonrelapse mortality, leukemia-free survival, and overall survival. In conclusion, donor-related variables significantly influence outcomes in patients with AML after Haplo-HSCT with PTCy. When possible, younger donors and male donors for male recipients should be prioritized. The use of bone marrow can additionally prevent GVHD.

Influence of donor-recipient sex on engraftment of normal and leukemia stem cells in xenotransplantation

Immunodeficient mouse models are widely used for the assessment of human normal and leukemic stem cells. Despite the advancements over the years, reproducibility, as well as the differences in the engraftment of human cells in recipient mice remains to be fully resolved. Here, we used various immunodeficient mouse models to characterize the effect of donor-recipient sex on the engraftment of the human leukemic and healthy cells. Donor human cells and recipient immunodeficient mice demonstrate sex-specific engraftment levels with significant differences observed in the lineage output of normal CD34+ hematopoietic stem and progenitor cells upon xenotransplantation. Intriguingly, human female donor cells display heightened sensitivity to the recipient mice's gender, influencing their proliferation and resulting in significantly increased engraftment in female recipient mice. Our study underscores the intricate interplay taking place between donor and recipient characteristics, shedding light on important considerations for future studies, particularly in the context of pre-clinical research.

Transplant Eligible and Ineligible Elderly Patients with AML-A Genomic Approach and Next Generation Questions

The management of elderly patients diagnosed with acute myelogenous leukemia (AML) is complicated by high relapse risk and comorbidities that often preclude access to allogeneic hematopoietic cellular transplantation (allo-HCT). In recent years, fast-paced FDA drug approval has reshaped the therapeutic landscape, with modest, albeit promising improvement in survival. Still, AML outcomes in elderly patients remain unacceptably unfavorable highlighting the need for better understanding of disease biology and tailored strategies. In this review, we discuss recent modifications suggested by European Leukemia Network 2022 (ELN-2022) risk stratification and review recent aging cell biology advances with the discussion of four AML cases. While an older age, >60 years, does not constitute an absolute contraindication for allo-HCT, the careful patient selection based on a detailed and multidisciplinary risk stratification cannot be overemphasized.

Reduced human leukocyte antigen mismatching is associated with more favourable outcomes after unrelated donor haematopoietic stem cell transplantation

The patient-donor human leukocyte antigen (HLA) match remains the most important prognostic factor for successful unrelated donor haematopoietic stem cell transplantation (UD-HSCT). This single-centre study comprised 125 adult patients with malignant haematological diseases undergoing their first UD-HSCT. The primary goal of this study was to validate the impact of HLA matching on HSCT outcomes, specifically at the HLA-DPB1 and HLA-DRB3/4/5 loci. A multivariable Cox regression analysis with a backward selection algorithm was employed to assess the associations of selected prognostic factors with outcomes after UD-HSCT. Any HLA locus mismatch was found to be associated with an increased incidence of grade II-IV acute graft versus host disease (aGvHD) at 100 days (p = .031; hazard ratio [HR] 1.935) and 6 months (p = .004; HR 2.284) after HSCT. The results of the following analyses also confirmed the strong impact of HLA-DPB1-only mismatch on the incidence of grade II-IV aGvHD at 100-day (p = .006; HR 2.642) as well as at 6-month (p = .007; HR 2.401) time periods. The HLA-DPB1-only mismatch was also shown to be statistically significantly associated with lower relapse incidence (p = .034; HR 0.333). The impact of the HLA-DRB3/4/5 mismatch on outcomes was inconclusive, though the two and more HLA-DPB1 + DRB3/4/5-only mismatches showed a trend towards worse outcomes than a single mismatch. Based on our findings and those of more comprehensive studies, the extended HLA loci typing of patients and donors is suggested to avoid unexpected HLA mismatches during the UD selection.

Development of an umbilical cord blood transplantation-specific nonrelapse mortality risk assessment score

ABSTRACT

Higher rate of nonrelapse mortality (NRM) remains yet to be resolved in umbilical cord blood transplantation (UCBT). Considering that UCBT has some unique features compared with allogeneic hematopoietic cell transplantation from other graft sources, a UCBT-specific NRM risk assessment system is required. Thus, in this study, we sought to develop a UCBT-specific NRM Risk Assessment (CoBRA) score. Using a nationwide registry database, we retrospectively analyzed 4437 recipients who had received their first single-unit UCBT. Using the backward elimination method, we constructed the CoBRA score in a training cohort (n = 2687), which consisted of recipients age ≥55 years (score 2), hematopoietic cell transplantation-specific comorbidity index ≥3 (score 2), male recipient, graft-versus-host disease prophylaxis other than tacrolimus in combination with methotrexate, performance status (PS) 2 to 4, HLA allele mismatch ≥ 2, refined Disease Risk Index high risk, myeloablative conditioning, and CD34+ cell doses < 0.82 × 105/kg (score 1 in each). The recipients were categorized into 3 groups: low (0-4 points), intermediate (5-7 points), and high (8-11 points) groups according to the CoBRA score. In the validation cohort (n = 1750), the cumulative incidence of NRM at 2 years was 14.9%, 25.5%, and 47.1% (P < .001), and 2-year overall survival (OS) was 74.2%, 52.7%, and 26.3% (P < .001) in the low, intermediate, and high groups, respectively. In summary, the CoBRA score could predict the NRM risk as well as OS after UCBT. Further external validation will be needed to confirm the significance of the CoBRA score.

Longitudinal clinical data improve survival prediction after hematopoietic cell transplantation using machine learning

ABSTRACT

Serial prognostic evaluation after allogeneic hematopoietic cell transplantation (allo-HCT) might help identify patients at high risk of lethal organ dysfunction. Current prediction algorithms based on models that do not incorporate changes to patients' clinical condition after allo-HCT have limited predictive ability. We developed and validated a robust risk-prediction algorithm to predict short- and long-term survival after allo-HCT in pediatric patients that includes baseline biological variables and changes in the patients' clinical status after allo-HCT. The model was developed using clinical data from children and young adults treated at a single academic quaternary-care referral center. The model was created using a randomly split training data set (70% of the cohort), internally validated (remaining 30% of the cohort) and then externally validated on patient data from another tertiary-care referral center. Repeated clinical measurements performed from 30 days before allo-HCT to 30 days afterwards were extracted from the electronic medical record and incorporated into the model to predict survival at 100 days, 1 year, and 2 years after allo-HCT. Naïve-Bayes machine learning models incorporating longitudinal data were significantly better than models constructed from baseline variables alone at predicting whether patients would be alive or deceased at the given time points. This proof-of-concept study demonstrates that unlike traditional prognostic tools that use fixed variables for risk assessment, incorporating dynamic variability using clinical and laboratory data improves the prediction of mortality in patients undergoing allo-HCT.

The Contemporary Role of Hematopoietic Stem Cell Transplantation in the Management of Chronic Myeloid Leukemia: Is It the Same in All Settings?

Hematopoietic stem cell transplantation (HSCT) for chronic myeloid leukemia (CML) patients has transitioned from the standard of care to a treatment option limited to those with unsatisfactory tyrosine kinase inhibitor (TKI) responses and advanced disease stages. In recent years, the threshold for undergoing HSCT has increased. Most CML patients now have life expectancies comparable to the general population, and therefore, the goal of therapy is shifting toward achieving treatment-free remission (TFR). While TKI discontinuation trials in CML show potential for achieving TFR, relapse risk is high, affirming allogeneic HSCT as the sole curative treatment. HSCT should be incorporated into treatment algorithms from the time of diagnosis and, in some patients, evaluated as soon as possible. In this review, we will look at some of the recent advances in HSCT, as well as its indication in the era of aiming for TFR in the presence of TKIs in CML.

Development and Validation of a Concise Objectifiable Risk Evaluation Score for Non-Relapse Mortality after Allogeneic Hematopoietic Stem Cell Transplantation

We aimed to develop a concise objectifiable risk evaluation (CORE) tool for predicting non-relapse mortality (NRM) and overall survival (OS) after allogeneic hematopoietic stem cell transplantation (allo-HCT). A total of 1120 adult patients who had undergone allo-HCT at our center between 2013 and 2020 were divided into training, first, and second validation cohorts. Objectifiable, patient-related factors impacting NRM in univariate and multivariate analyses were: serum albumin, serum creatinine, serum C-reactive protein (CRP), heart function (LVEF), lung function (VC, FEV1), and patient age. Hazard ratios were assigned points (0-3) based on their impact on NRM and summed to the individual CORE HCT score. The CORE HCT score stratified patients into three distinct low-, intermediate-, and high-risk groups with two-year NRM rates of 9%, 22%, and 46%, respectively, and OS rates of 73%, 55%, and 35%, respectively (p < 0.001). These findings were confirmed in a first and a second recently treated validation cohort. Importantly, the CORE HCT score remained informative across various conditioning intensities, disease-specific subgroups, and donor types, but did not impact relapse incidence. A comparison of CORE HCT vs. HCT Comorbidity Index (HCT-CI) in the second validation cohort revealed better performance of the CORE HCT score with c-statistics for NRM and OS of 0.666 (SE 0.05, p = 0.001) and 0.675 (SE 0.039, p < 0.001) vs. 0.431 (SE 0.057, p = 0.223) and 0.535 (SE 0.042, p = 0.411), respectively. The CORE HCT score is a concise and objectifiable risk evaluation tool for adult patients undergoing allo-HCT for malignant disease. External multicenter validation is underway.

Endothelial Activation and Stress Index (EASIX) to predict mortality after allogeneic stem cell transplantation: a prospective study

BACKGROUND

We previously reported that the "Endothelial Activation and Stress Index" (EASIX; ((creatinine×lactate dehydrogenase)÷thrombocytes)) measured before start of conditioning predicts mortality after allogeneic hematopoietic stem cell transplantation (alloSCT) when used as continuous score. For broad clinical implementation, a prospectively validated EASIX-pre cut-off is needed that defines a high-risk cohort and is easy to use.

METHOD

In the current study, we first performed a retrospective cohort analysis in n=2022 alloSCT recipients and identified an optimal cut-off for predicting non-relapse mortality (NRM) as EASIX-pre=3. For cut-off validation, we conducted a multicenter prospective study with inclusion of n=317 first alloSCTs from peripheral blood stem cell in adult patients with acute leukemia, lymphoma or myelodysplastic syndrome/myeloproliferative neoplasms in the European Society for Blood and Marrow Transplantation network.

RESULTS

Twenty-three % (n=74) of alloSCT recipients had EASIX-pre ≥3 taken before conditioning. NRM at 2 years was 31.1% in the high EASIX group versus 11.5% in the low EASIX group (p<0.001). Patients with high EASIX-pre also had worse 2 years overall survival (51.6% vs 70.9%; p=0.002). We were able to validate the cut-off and found that EASIX ≥3 was associated with more than twofold increased risk for NRM in multivariate analysis (HR=2.18, 95% CI 1.2 to 3.94; p=0.01). No statistically significant difference could be observed for the incidence of relapse.

CONCLUSIONS

The results of this study provide a prospectively validated standard laboratory biomarker index to estimate the transplant-related mortality risk after alloSCT. EASIX ≥3 taken before conditioning identifies a population of alloSCT recipients who have a more than twofold increased risk of treatment-related mortality.

Hematopoietic cell transplantation and cellular therapies in Switzerland. Evolution over 25 years. A report from the stem cell transplantation and cellular therapies working groups of the SBST 1997-2021

The Swiss Blood Stem Cell Transplantation and Cellular Therapy Group (SBST) leads a mandatory national registry for all hematopoietic stem cell transplants (HCT) and cellular therapies. After 25 years, information was available for 11,226 patients receiving an HCT (4031 allogeneic and 7195 autologous), including 925 pediatric patients. We compared patient characteristics and outcome by quinquennia 1997-2001, 2002-2006, 2007-2011, 2012-2016, and 2017-2021. There were numerous changes over time. Allogeneic transplant recipients became older (median age 33.7 vs. 54.3) and had more frequently unrelated donors and reduced intensity conditioning in later quinquennia. Similarly, age increased for recipients of autologous HCT (median 48.3 vs. 59.9). We did not see a significant drop in transplant activity during the SARS-CoV-2 pandemic. Analysis of outcome showed overall survival (relative risk (RR) of death 0.664 (0.529-0.832) and progression free survival (RR 0.708 (0.577-0.870) being improved over time comparing the latest to the first quinquennium adjusting for risk factors. Non-relapse mortality decreased in recipients of allogeneic HCT (RR: 0.371 (0.270-0.509)) over time but relapse risks did not. Outcome of autologous HCT improved as well across quinquennia, this improvement was mainly due to decreased relapse risks (RR 0.681 (0.597-0.777)), possibly related to maintenance treatment or rescue treatment for relapse mainly in myeloma patients. Cellular therapies other than allogeneic or autologous HCT, particularly chimeric antigen receptor T-cells (CAR-T) treatment have started to increase after 2019, year of approval of the first commercial CAR-T product in Switzerland. Data on chimeric antigen receptor T-cell treatment are too early for comparative analyses. Detailed analyses of changes over time are presented. This study includes all HCTs, and cellular therapies, data useful for quality assurance programs, health care cost estimation and benchmarking. Between 50% and 60% of patients are long-term survivors after both types of HCT, indicating growing populations of surviving patients requiring long-term care.

Predicting Patient Death after Allogeneic Stem Cell Transplantation for Inborn Errors Using Machine Learning (PREPAD): A European Society for Blood and Marrow Transplantation Inborn Errors Working Party Study

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for many inborn errors of immunity, metabolism, and hematopoiesis. No predictive models are available for these disorders. We created a machine learning model using XGBoost to predict survival after HSCT using European Society for Blood and Marrow Transplant registry data of 10,888 patients who underwent HSCT for inborn errors between 2006 and 2018, and compared it to a simple linear Cox model, an elastic net Cox model, and a random forest model. The XGBoost model had a cross-validated area under the curve value of .73 at 1 year, which was significantly superior to the other models, and it accurately predicted for countries excluded while training. It predicted close to 0% and >30% mortality more often than other models at 1 year, while maintaining good calibration. The 5-year survival was 94.7% in the 25% of patients at lowest risk and 62.3% in the 25% at highest risk. Within disease and donor subgroups, XGBoost outperformed the best univariate predictor. We visualized the effect of the main predictors-diagnosis, performance score, patient age and donor type-using the SHAP ML explainer and developed a stand-alone application, which can predict using the model and visualize predictions. The risk of mortality after HSCT for inborn errors can be accurately predicted using an explainable machine learning model. This exceeds the performance of models described in the literature. Doing so can help detect deviations from expected survival and improve risk stratification in trials.

Haploidentical and Matched Sibling Transplantation for Acute Myeloid Leukemia: A Hospital-Based Study

Background

Allogeneic peripheral blood stem cell transplantation (PBSCT) has been increasing for the last years in Latin America. The objective of this study was to describe clinical outcomes in acute myeloid leukemia (AML) receiving allogeneic PBSCT between 2013 and 2019 in a single center of Cali, Colombia.

Methods

A retrospective cohort study was conducted in Fundacion Valle del Lili. Patients diagnosed with AML who received an allogeneic PBSCT between 2013 and 2019 using human leukocyte antigen (HLA)-matched sibling donors (MSDs) or haploidentical related donors (HRDs) with myeloablative conditioning regimen were included. Cases with diagnosis of promyelocytic leukemia, myelodysplastic syndrome-related AML and therapy-related AML were excluded. Data were obtained directly from the hospital PBSCT database and clinical records.

Results

A total of 50 patients were included (HRD, n = 32; MSD, n = 18). Sixty-two percent was in the first complete remission (CR1) at the time of the transplant, of which 26% were MSD and 74% were HRD. The European Group for Blood and Marrow Transplantation (EBMT) risk score was: 44% vs. 50% low, 28% vs. 28% intermediate and 28% vs. 22% high for MSD vs. HRD, respectively. Overall survival at 5 years for MSD was 62% (95% confidence interval (CI): 31-83%) and 43% (95% CI: 25-60%) for HRD. Event-free survival was 56% (95% CI: 26-78%) and 35.6% (95% CI: 18-53%), respectively. Non-relapse mortality at day-100 was 6% (95% CI: 0.8-35%) and 20% (95% CI: 9-39%). Relapse at5 years was 18% (95% CI: 4-58%) and 25% (95% CI: 10-52%). Overall mortality rate was 46%. The grade II-IV, III-IV acute graft-versus-host disease and severe chronic graft-versus-host disease was 44%, 11% and 12% for MSD, and 43%, 9% and 0% for HRD.

Conclusion

These results underline that MSD remains the first donor choice for AML patients in CR1 when available. HRDs are still our next option among alternative donors. It is necessary to find strategies that have a positive impact on those outcomes that markedly affect the quality of allogeneic PBSCT and the prognosis of patients. Comparative, randomized, prospective studies with longer follow-up of haploidentical allogeneic PBSCT with other donor types are required to definitely establish its role among alternative donors.

Unrelated female-to-male bone marrow transplantation would be preferred over cord blood transplantation in male patients

BACKGROUND AIMS

Allogeneic hematopoietic stem cell transplantation from female donors to male recipients (female-to-male allo-HCT) is a well-established risk factor for a greater incidence of non-relapse mortality (NRM) and chronic graft-versus-host disease (GVHD). In contrast, unrelated cord blood transplantation (UCBT) is associated with a lower incidence of chronic GVHD. In this study, survival outcomes were compared between the UCBT and unrelated female-to-male bone marrow transplantation (UFMBMT) groups.

METHODS

We evaluated male allo-HCT recipients who underwent UCBT or UFMBMT between 2012 and 2020 in Japan. There were 2517 cases in the UCBT group, 456 cases in the HLA-matched UFMBMT group and 457 cases in the HLA-mismatched UFMBMT group.

RESULTS

HLA-mismatched UFMBMT was significantly associated with a decreased risk of relapse (hazard ratio [HR] 0.74; 95% confidence interval [CI] 0.57-0.98], P = 0.033) and HLA-matched UFMBMT had the tendency of a decreased risk of relapse (HR 0.78; 95% CI 0.61-1.01, P = 0.059). HLA-matched UFMBMT was also associated with favorable OS (HR 0.82; 95% CI 0.69-0.97, P = 0.021). The relationship between the donor sources and relapse was similarly observed in the lymphoid malignancy cohort.

CONCLUSIONS

The difference of graft-versus leukemia effect by H-Y immunity according to donor sources might contribute to the difference in clinical impact. It might be desirable for patients who could sufficiently wait for donor coordination to select BMT rather than UCBT, even if only unrelated female donors are available for male recipients.

What Influences the Decision to Proceed to Transplant for Patients With AML in First Remission?

Although allogeneic hematopoietic cell transplantation (allo-HCT) remains the backbone of curative treatment for the majority of fit adults diagnosed with AML, there is indeed a subset of patients for whom long-term remission may be achieved without transplantation. Remarkable changes in our knowledge of AML biology in recent years has transformed the landscape of diagnosis, management, and treatment of AML. Specifically, markedly increased understanding of molecular characteristics of AML, the expanded application of minimal/measurable residual diseases testing, and an increased armamentarium of leukemia-directed therapeutic agents have created a new paradigm for the medical care of patients with AML. An attempt is herein made to decipher the decision to proceed to transplant for patients with AML in first complete remission on the basis of the current best available evidence. The focus is on factors affecting the biology and treatment of AML itself, rather than on variables related to allo-HCT, an area characterized by significant advancements that have reduced overall therapy-related complications. This review seeks to focus on areas of particular complexity, while simultaneously providing clarity on how our current knowledge and treatment strategies may, or may not, influence the decision to pursue allo-HCT in patients with AML.

Machine Learning for the Prediction of Survival Post-Allogeneic Hematopoietic Cell Transplantation: A Single-Center Experience

INTRODUCTION

Prediction of outcomes following allogeneic hematopoietic cell transplantation (HCT) remains a major challenge. Machine learning (ML) is a computational procedure that may facilitate the generation of HCT prediction models. We sought to investigate the prognostic potential of multiple ML algorithms when applied to a large single-center allogeneic HCT database.

METHODS

Our registry included 2,697 patients that underwent allogeneic HCT from January 1976 to December 2017. 45 pretransplant baseline variables were included in the predictive assessment of each ML algorithm on overall survival (OS) as determined by area under the curve (AUC). Pretransplant variables used in the EBMT ML study (Shouval et al., 2015) were used as a benchmark for comparison.

RESULTS

On the entire dataset, the random forest (RF) algorithm performed best (AUC 0.71 ± 0.04) compared to the second-best model, logistic regression (LR) (AUC = 0.69 ± 0.04) (p < 0.001). Both algorithms demonstrated improved AUC scores using all 45 variables compared to the limited variables examined by the EBMT study. Survival at 100 days post-HCT using RF on the full dataset discriminated patients into different prognostic groups with different 2-year OS (p < 0.0001). We then examined the ML methods that allow for significant individual variable identification, including LR and RF, and identified matched related donors (HR = 0.49, p < 0.0001), increasing TBI dose (HR = 1.60, p = 0.006), increasing recipient age (HR = 1.92, p < 0.0001), higher baseline Hb (HR = 0.59, p = 0.0002), and increased baseline FEV1 (HR = 0.73, p = 0.02), among others.

CONCLUSION

The application of multiple ML techniques on single-center allogeneic HCT databases warrants further investigation and may provide a useful tool to identify variables with prognostic potential.

Fifty years of BMT: risk stratification, donor matching, and stem cell collection for transplantation

In this review, we discuss recipient risk assessment for allo-HCT regarding comorbidities present at baseline to predict non relapse mortality. We further reviewed the incorporation of remission status and cytogenetic risk prior to allograft transplantation to predict relapse rates for hematologic malignancies. HCT-CI and DRI are tools available to physicians to assess the risk-benefit of allo-HCT in patients referred for transplantation. Next, we discuss our algorithm for donor selection and criteria for donor selection in case matched donors are not available. Finally, we discuss our approach for stem cell mobilization, especially in donors failing G-CSF, and our approach for the use of plerixafor and data supporting its use.

Age and allogeneic hematopoietic cell transplantation outcomes in acute myeloid leukemia

Although several studies have reported significant effects of patient age on outcomes of allogeneic hematopoietic cell transplantation (HCT), the prognostic relevance of age must be determined separately for myeloablative conditioning (MAC) and reduced-intensity conditioning (RIC). We analyzed Japanese nationwide transplantation registry data of patients aged 20-79 years with acute myeloid leukemia who underwent allogeneic HCT using MAC (n = 7525) or RIC (n = 3154) between 2008 and 2019. Patient were divided into six groups by age, with each group representing a decade, and overall survival (OS), relapse, and non-relapse mortality (NRM) were compared between adjacent age groups. The adverse impact of age on OS increased each decade starting at age 40 among patients receiving MAC, but only differed significantly between patients in their 50s and 60s among those receiving RIC. In patients receiving both MAC and RIC, the detrimental effect of advanced age on OS was accompanied by an increased risk of NRM. These findings show that age affects NRM and OS significantly, but differs depending on conditioning intensity. RIC mitigates the adverse prognostic impact of older age and is thus considered a reasonable option for older patients.

Prediction of Nonrelapse Mortality in Patients With Acute Myeloid Leukemia and Acute Lymphoblastic Leukemia Receiving Allogeneic Stem Cell Transplantation With Posttransplantation Cyclophosphamide-based Graft Versus Host Disease Prophylaxis

Graft versus host disease (GVHD) prophylaxis with posttransplantation cyclophosphamide (PTCY) has been established to reduce severe GVHD, and thereby potentially reducing nonrelapse mortality (NRM) after allogeneic stem cell transplantation (alloSCT). We evaluated the predictive capacity of established NRM-risk scores in patients receiving PTCY-based GVHD prophylaxis, and subsequently developed and validated a novel PTCY-specific NRM-risk model. Adult patients (n = 1861) with AML or ALL in first complete remission who received alloSCT with PTCY-based GVHD prophylaxis were included. The PTCY-risk score was developed using multivariable Fine and Gray regression, selecting parameters from the hematopoietic cell transplantation-comorbidity index (HCT-CI) and European Group for Blood and Marrow Transplantation (EBMT) score with a subdistribution hazard ratio (SHR) of ≥1.2 for 2-year NRM in the training set (70% split), which was validated in the test set (30%). The performance of the EBMT score, HCT-CI, and integrated EBMT score was relatively poor for discriminating 2-year NRM (c-statistic 51.7%, 56.6%, and 59.2%, respectively). The PTCY-risk score included 10 variables which were collapsed in 3 risk groups estimating 2-year NRM of 11% ± 2%, 19% ± 2%, and 36% ± 3% (training set, c-statistic 64%), and 11% ± 2%, 18% ± 3%, and 31% ± 5% (test set, c-statistic 63%), which also translated into different overall survival. Collectively, we developed an NRM-risk score for acute leukemia patients receiving PTCY that better predicted 2-year NRM compared with existing models, which might be applicable to the specific toxicities of high-dose cyclophosphamide.

Statin-based endothelial prophylaxis and outcome after allogeneic stem cell transplantation

BACKGROUND

Allogeneic haematopoietic stem cell transplantation (alloSCT) often remains the only curative therapy for hematologic malignancies. Although the management of transplant-associated adverse events considerably improved over the last decades, nonrelapse mortality (NRM) remains a challenge, and endothelial dysfunction was identified as a major contributor to NRM.

METHODS

Statin-based endothelial prophylaxis (SEP) has been implemented in the standard of care in our transplant centre to reduce NRM caused by endothelial injury. Here, we retrospectively analysed the impact of SEP on clinical outcome in a cohort of 347 alloSCT patients.

RESULTS

SEP (n = 209) was associated with significantly reduced NRM (hazard ratio 0.61, 95% CI 0.38-0.96) and better overall survival (OS) after acute graft-versus-host disease (HR 0.59, 95% CI 0.37-0.93). Subgroup analyses showed that the NRM benefit was mainly found in patients with an intermediate endothelial activation and stress index (EASIX), while relapse risk was not affected. On day 100 post-alloSCT, patients receiving SEP had significantly higher levels of the rate-limiting enzyme of tryptophan metabolism, indoleamine 2,3-dioxygenase (IDO), higher kynurenine to tryptophan ratios as a proxy of IDO activity and tended to have lower levels of the endothelial injury marker ST2 (p = .055). No significant differences in interferon-gamma or IL18 levels were observed. These biomarker signatures suggest that the beneficial effects of SEP might be mediated by both endothelial protection and immunomodulation.

CONCLUSIONS

Together, these data suggest that SEP improves NRM and OS post-alloSCT in particular in patients with intermediate endothelial risk and provide first mechanistic clues about its potential mode of action.

Clinical characteristics of steroid-responsive but dependent chronic graft-versus-host disease: a multicenter retrospective analysis

Chronic graft-versus-host disease (cGVHD) is a long-term complication of allogeneic hematopoietic stem cell transplantation. The clinical importance of long-term corticosteroid dependency in steroid-responsive cGVHD is undetermined. We retrospectively reviewed the data of 120 consecutive patients who received systemic steroid therapy for cGVHD between January 2007 and December 2018 at three institutions. Among patients with steroid-responsive cGVHD, those who successfully tapered off corticosteroids within 1 year were defined as the early withdrawal group (EW-cGVHD) and others were defined as the dependent group (Dp-cGVHD). Twenty-six patients were classified as EW-cGVHD and 55 as Dp-cGVHD. The proportion of men was significantly higher and performance status was significantly better in EW-cGVHD. The 5-year overall survival and cGVHD recurrence-free survival rates were significantly higher in EW-cGVHD than Dp-cGVHD (96% vs. 68%, p = 0.017 and 84% vs. 41%, p = 0.002, respectively). While the relapse-free survival rate did not differ significantly (84% vs. 65%, p = 0.15), the proportion of patients requiring readmission, mainly due to cGVHD recurrence or infection, was significantly increased in Dp-cGVHD (38% vs. 84%, p < 0.001). In summary, steroid dependency in cGVHD for more than 1 year was significantly associated with poor transplant outcomes.

Applicability of the acute leukemia (AL) - EBMT score as a prognostic model for allogeneic hematopoietic stem cell transplantation: a single-center, prospective, cohort study at a reference transplant center in Brazil

INTRODUCTION

The Acute Leukemia-European Society for Blood and Marrow Transplantation (AL-EBMT) risk score was recently developed and validated by Shouval et al. OBJECTIVE: To assess the ability of this score in predicting the 2-year overall survival (OS-2), leukemia-free survival (LFS-2) and transplant-related mortality (TRM) in acute leukemia (AL) adult patients undergoing a first allogeneic hematopoietic stem cell transplant (HSCT) at a transplant center in Brazil.

METHODS

In this prospective, cohort study, we used the formula published by Shouval et al. to calculate the AL-EBMT score and stratify patients into three risk categories.

RESULTS

A total of 79 patients transplanted between 2008 and 2018 were analyzed. The median age was 38 years. Acute myeloid leukemia was the most common diagnosis (68%). Almost a quarter of the cases were at an advanced stage. All hematopoietic stem cell transplantations (HSCTs) were human leukocyte antigen-matched (HLA-matched) and the majority used familial donors (77%). Myeloablative conditioning was used in 92% of the cases. Stratification according to the AL-EBMT score into low-, intermediate- and high-risk groups yielded the following results: 40%, 12% and 47% of the cases, respectively. The high scoring group was associated with a hazard ratio of 2.1 (p = 0.007), 2.1 (p = 0.009) and 2.47 (p = 0.01) for the 2-year OS, LFS and TRM, respectively.

CONCLUSION

This study supports the ability of the AL-EBMT score to reasonably predict the 2-year post-transplant OS, LFS and TRM and to discriminate between risk categories in adult patients with AL, thus confirming its usefulness in clinical decision-making in this setting. Larger, multicenter studies may further help confirm these findings.

Treatment options for acute myeloid leukemia patients aged <60 years

Treatment of acute myeloid leukemia (AML) has changed over the last few years, after the discovery of new drugs selectively targeting AML blasts. Although 3/7 remains the standard of care for most AML patients, several new targeted agents (such as FLT3 inhibitors, CPX-351, gemtuzumab ozogamicin, BCL-2 inhibitor, and oral azacitidine), either as single agents or combined with standard chemotherapy, are approaching clinical practice, starting a new era in AML management. Moreover, emerging evidence has demonstrated that high-risk AML patients might benefit from both allogeneic stem cell transplant and maintenance therapy, providing new opportunities, as well as new challenges, for treating clinicians. In this review, we summarize available data on first-line therapy in young AML patients focusing on targeted therapies, integrating established practice with new evidence, in the effort to outline the contours of a new therapeutic paradigm, that of a “total therapy”, which goes beyond obtaining complete remission.

Time-dependent prediction of mortality and cytomegalovirus reactivation after allogeneic hematopoietic cell transplantation using machine learning

Allogeneic hematopoietic cell transplantation (HCT) effectively treats high-risk hematologic diseases but can entail HCT-specific complications, which may be minimized by appropriate patient management, supported by accurate, individual risk estimation. However, almost all HCT risk scores are limited to a single risk assessment before HCT without incorporation of additional data. We developed machine learning models that integrate both baseline patient data and time-dependent laboratory measurements to individually predict mortality and cytomegalovirus (CMV) reactivation after HCT at multiple time points per patient. These gradient boosting machine models provide well-calibrated, time-dependent risk predictions and achieved areas under the receiver-operating characteristic of 0.92 and 0.83 and areas under the precision-recall curve of 0.58 and 0.62 for prediction of mortality and CMV reactivation, respectively, in a 21-day time window. Both models were successfully validated in a prospective, non-interventional study and performed on par with expert hematologists in a pilot comparison.

The Clinical Value of Procalcitonin in the Neutropenic Period After Allogeneic Hematopoietic Stem Cell Transplantation

The diagnostic value of procalcitonin and the prognostic role of PCT clearance remain unclear in neutropenic period after allogeneic hematopoietic stem cell transplantation introduction. This study evaluated 219 febrile neutropenic patients (116, retrospectively; 103, prospectively) who underwent allo-HSCT from April 2014 to March 2016. The area under the receiver operator characteristic curve (AUC) of PCT for detecting documented infection (DI) was 0.637, and that of bloodstream infection (BSI) was 0.811. In multivariate analysis, the inability to decrease PCT by more than 80% within 5–7 days after the onset of fever independently predicted poor 100-day survival following allo-HSCT (P = 0.036). Furthermore, the prognostic nomogram combining PCTc and clinical parameters showed a stable predictive performance, supported by the C-index of 0.808 and AUC of 0.813 in the primary cohort, and C-index of 0.691 and AUC of 0.697 in the validation cohort. This study demonstrated the diagnostic role of PCT in documented and bloodstream infection during the neutropenic period after allo-HSCT. PCTc might serve as a predictive indicator of post-HSCT 100-day mortality. A nomogram based on PCTc and several clinical factors effectively predicted the 100-day survival of febrile patients and may help physicians identify high-risk patients in the post-HSCT neutropenic period.

The improvement in overall survival from unrelated donor transplantation in Australia and New Zealand is driven by a reduction in non-relapse mortality: A study from the ABMTRR

Unrelated donors (UDs) are the commonest source for allogeneic transplantation (alloSCT), with higher non-relapse mortality (NRM) than siblings. We analyzed data from the Australasian Bone Marrow Transplant Recipient Registry from adults receiving a first UD alloSCT during 2001-2015, to determine whether and how NRM has changed. Predictors of outcome were determined using cox regression, accounting for time-interactions and competing risks. A total of 2308 patients met inclusion criteria. Changes over time included increasing age, utilization of peripheral blood cells, reduced intensity conditioning, and T-cell depletion. Three-year OS increased significantly from 44% in 2001-2005 to 58% in 2011-2015 (p < 0.001). This was attributed to a reduction in NRM from 35% to 24% (p < 0.001) with no change in relapse. Factors associated with increased NRM included age, male sex, CMV seropositivity, HLA mismatch, transplant more than 6 months from diagnosis, and T-cell depletion when administered during 2001-2005. Survival following UD SCT has improved by almost 15% over the past decade, driven by improvements in NRM. This has occurred despite increasing recipient age and appears to be due to better donor selection, reduced delays to transplantation, and improved prevention and management of GVHD.

External Validation of the Revised Pretransplant Assessment of Mortality Score in Allogeneic Hematopoietic Cell Transplantation: A Cohort Study

Pretransplant risk scores such as the revised Pretransplant Assessment of Mortality (rPAM) score help to predict outcome of patients receiving allogeneic hematopoietic cell transplantation (allo-HCT). Since the rPAM has not been validated externally in a heterogeneous patient population with different diseases, we aimed to validate the rPAM score in a real-world cohort of allo-HCT patients. A total of 429 patients were included receiving their first allo-HCT from 2008 to 2015. The predictive capacity of the rPAM score for 4-year overall survival (OS), nonrelapse mortality (NRM), and cumulative incidence of relapse (CIR) after allo-HCT was evaluated. Moreover, we evaluated the impact of the rPAM score for OS and used uni- and multivariable analyses to identify patient- and transplant-related predictors for OS. In rPAM score categories of <17, 17–23, 24–30, and >30, the OS probability at 4 years differed significantly with 61%, 36%, 26%, and 10%, respectively (P < 0.0001). In contrast to CIR, the NRM increased significantly in patients with higher rPAM scores (P < 0.001). Regarding the OS, the rPAM score had an area under the receiver operating characteristics curve of 0.676 (95% confidence interval [CI], 0.625-0.727) at 4 years. In the multivariable analysis, the rPAM score was associated with OS—independently of conditioning regimens (adjusted hazard ratio per 1-unit increase, 1.10; 95% CI, 1.06-1.10; P < 0.001). Additionally, forced expiratory volume in 1 second and the disease risk index were the components of the rPAM significantly associated with outcome. In our large real-world cohort with extended follow-up, the rPAM score was validated as an independent predictor of OS in patients with hematologic disorders undergoing allo-HCT.

Predicting Long-term Survival After Allogeneic Hematopoietic Cell Transplantation in Patients With Hematologic Malignancies: Machine Learning-Based Model Development and Validation

Background

Scoring systems developed for predicting survival after allogeneic hematopoietic cell transplantation (HCT) show suboptimal prediction power, and various factors affect posttransplantation outcomes.

Objective

A prediction model using a machine learning–based algorithm can be an alternative for concurrently applying multiple variables and can reduce potential biases. In this regard, the aim of this study is to establish and validate a machine learning–based predictive model for survival after allogeneic HCT in patients with hematologic malignancies.

Methods

Data from 1470 patients with hematologic malignancies who underwent allogeneic HCT between December 1993 and June 2020 at Asan Medical Center, Seoul, South Korea, were retrospectively analyzed. Using the gradient boosting machine algorithm, we evaluated a model predicting the 5-year posttransplantation survival through 10-fold cross-validation.

Results

The prediction model showed good performance with a mean area under the receiver operating characteristic curve of 0.788 (SD 0.03). Furthermore, we developed a risk score predicting probabilities of posttransplantation survival in 294 randomly selected patients, and an agreement between the estimated predicted and observed risks of overall death, nonrelapse mortality, and relapse incidence was observed according to the risk score. Additionally, the calculated score demonstrated the possibility of predicting survival according to the different transplantation-related factors, with the visualization of the importance of each variable.

Conclusions

We developed a machine learning–based model for predicting long-term survival after allogeneic HCT in patients with hematologic malignancies. Our model provides a method for making decisions regarding patient and donor candidates or selecting transplantation-related resources, such as conditioning regimens.

Pre-Transplant Serum Leptin Levels and Relapse of Acute Myeloid Leukemia after Allogeneic Transplantation

Weight loss and metabolic activity influence outcome after allogeneic stem cell transplantation (alloSCT). This study evaluates pre-conditioning Leptin, a peptide hormone involved in metabolism and immune homeostasis, as a prognostic factor for survival, relapse and non-relapse mortality (NRM) following alloSCT. Leptin serum levels prior to conditioning were determined in a cohort of patients transplanted for various hematologic malignancies (n = 524) and correlated retrospectively with clinical outcome. Findings related to patients with acute leukemia (AL) from this sample were validated in an independent cohort. Low pre-conditioning serum Leptin was an independent prognostic marker for increased risk of relapse (but not of NRM and overall mortality) following alloSCT for AL of intermediate and advanced stage (beyond first complete remission). Multivariate analysis revealed a hazard ratio (HR) for relapse of 0.75 per log2 increase (0.59–0.96, p = 0.020). This effect was similar in an independent validation cohort. Pre-conditioning serum Leptin was validated as a prognostic marker for early relapse by fitting the multivariate Cox model to the validation data. Pre-conditioning serum Leptin levels may serve as an independent prognostic marker for relapse following alloSCT in intermediate and advanced stage AL patients. Prospective studies are required to prove whether serum Leptin could be used for guiding nutritional intervention in patients with AL undergoing alloSCT.

OUP accepted manuscript

As in younger patients, allogeneic stem cell transplantation (alloHSCT) offers the best chance for durable remission in older patients (≥60 years) with acute myeloid leukemia (AML). However, defining the best treatment strategy (and in particular, whether or not to proceed to alloHSCT) for elderly patients with AML remains a difficult decision for the hematologist, since potential toxicity of conditioning regimens, risks of graft-versus-host disease, impaired immune reconstitution and the need for prolonged immunosuppression may be of major concern in these vulnerable patients with complex needs. Hopefully, significant progress has been made over the past decade in alloHSCT for elderly patients and current evidence suggests that chronological age per se (between 60 and 75) is not a reliable predictor of outcome after alloHSCT. Here, we review the current state of alloHSCT in elderly patients with AML and also discuss the different approaches currently being investigated to improve both accessibility to as well as success of alloHSCT in these patients.

How I Use Measurable Residual Disease in the Clinical Management of Adult Acute Lymphoblastic Leukemia

Over the last decade the use of measurable residual disease (MRD) diagnostics in adult acute lymphoblastic leukemia (ALL) has expanded from a limited number of study groups in Europe and the United States to a world-wide application. In this review, we summarize the advantages and drawbacks of the current available techniques used for MRD monitoring. Through the use of three representative case studies, we highlight the advances in the use of MRD in clinical decision-making in the management of ALL in adults. We acknowledge discrepancies in MRD monitoring and treatment between different countries, reflecting differing availability, accessibility and affordability.

Outcomes of patients diagnosed with chronic lymphocytic leukemia after allogeneic hematopoietic stem cell transplantation: Results from a tertiary care center

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HCT) is currently the only curative treatment for patients with chronic lymphocytic leukemia (CLL).

METHODS

We analyzed the outcomes of 93 patients (median age: 52 years) who underwent allo-HCT at our center between 1989 and 2019.

RESULTS

After a median follow-up of 35 months, relapse was observed in 15.1% (n = 14) patients. The estimated 2-year non-relapse mortality, relapse-free survival, and overall survival (OS) were 38.1%, 54.2%, and 58.7%, respectively. The ECOG performance status ≥ 2 (hazard ratio [HR]: 4.1; p = .001) and use of total body irradiation (in a myeloablative conditioning regimen; HR: 2.64; p = .005) were predictive of poor OS after multivariable analysis. The occurrence of sinusoidal obstruction syndrome/veno-occlusive disease post-transplant was associated with poor survival (p = .001).

CONCLUSION

Although the use of kinase and bcl2 inhibitors may result in a decrease in the number and need of transplants, allo-HCT remains a viable option in selected patients with high-risk CLL and good performance status.

GITMO Registry Study on Allogeneic Transplantation in Patients Aged ≥60 Years from 2000 to 2017: Improvements and Criticisms

Today, allogeneic stem cell transplantation (allo-SCT) can be offered to patients up to age 70 to 72 years and represents one of the most effective curative treatments for many hematologic malignancies. The primary objective of the study was to collect data from the allo-SCTs performed in Italy between 2000 and 2017 in patients aged ≥60 years to evaluate the changes in safety and efficacy outcomes, as well as their distribution and characteristics over time. The Italian Group for Bone Marrow Transplantation, Hematopoietic Stem Cells and Cell Therapy (GITMO) AlloEld study (ClinicalTrials.gov identifier NCT04469985) is a retrospective analysis of allo-SCTs performed at 30 Italian transplantation centers in older patients (age ≥60 years) between 2000 and 2017 (n = 1996). For the purpose of this analysis, patients were grouped into 3 time periods: time A, 2000 to 2005 (n = 256; 12%); time B, 2006 to 2011 (n = 584; 29%); and time C, 2012 to 2017 (n = 1156; 59%). After a median follow-up of 5.6 years, the 5-year nonrelapse mortality (NRM) remained stable (time A, 32.8%; time B, 36.2%; and time C, 35.0%; P = .5), overall survival improved (time A, 28.4%; time B, 31.8%; and time C, 37.3%; P = .012), and the cumulative incidence of relapse was reduced (time A, 45.3%; time B, 38.2%; time C, 30.0%; P < .0001). The 2-year incidence of extensive chronic graft-versus-host disease was reduced significantly (time A, 17.2%; time B, 15.8%; time C, 12.2%; P = .004). Considering times A and B together (2000 to 2011), the 2-year NRM was positively correlated with the Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI) score; NRM was 25.2% in patients with an HCT-CI score of 0, 33.9% in those with a score of 1 or 2, and 36.1% in those with a score of 3 (P < .001). However, after 2012, the HCT-CI score was not significantly predictive of NRM. This study shows that the transplantation procedure in elderly patients became more effective over time. Relapse incidence remains the major problem, and strategies to prevent it are currently under investigation (eg, post-transplantation maintenance). The selection of patients aged ≥60 could be improved by combining HCT-CI and frailty assessment to better predict NRM.

A novel Iowa-Mayo validated composite risk assessment tool for allogeneic stem cell transplantation survival outcome prediction

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative option for many hematologic conditions and is associated with considerable morbidity and mortality. Therefore, prognostic tools are essential to navigate the complex patient, disease, donor, and transplant characteristics that differentially influence outcomes. We developed a novel, comprehensive composite prognostic tool. Using a lasso-penalized Cox regression model (n = 273), performance status, HCT-CI, refined disease-risk index (rDRI), donor and recipient CMV status, and donor age were identified as predictors of disease-free survival (DFS). The results for overall survival (OS) were similar except for recipient CMV status not being included in the model. Models were validated in an external dataset (n = 378) and resulted in a c-statistic of 0.61 and 0.62 for DFS and OS, respectively. Importantly, this tool incorporates donor age as a variable, which has an important role in HSCT outcomes. This needs to be further studied in prospective models. An easy-to-use and a web-based nomogram can be accessed here: https://allohsctsurvivalcalc.iowa.uiowa.edu/ .

Development of a Nomogram for Predicting the Cumulative Incidence of Disease Recurrence of AML After Allo-HSCT

Using targeted exome sequencing, we studied correlations between mutations at diagnosis and transplant outcomes in 332 subjects with acute myeloid leukemia (AML) receiving allotransplantation. A total of 299 patients (299/332, 90.1%) had at least one oncogenic point mutation. In multivariable analyses, pretransplant disease status, minimal residual disease (MRD) before transplantation (pre-MRD), cytogenetic risk classification, and TP53 and FLT3-ITD^{high ratio} mutations were independent risk factors for AML recurrence after allotransplantation (p < 0.05). A nomogram for the cumulative incidence of relapse (CIR) that integrated all the predictors in the multivariable model was then constructed, and the concordance index (C-index) values at 6, 12, 18, and 24 months for CIR prediction were 0.754, 0.730, 0.715, and 0.690, respectively. Moreover, calibration plots showed good agreements between the actual observation and the nomogram prediction for the 6, 12, 18, and 24 months posttransplantation CIR in the internal validation. The integrated calibration index (ICI) values were 0.008, 0.055, 0.094, and 0.136 at 6, 12, 18, and 24 months posttransplantation, respectively. With a median cutoff score of 9.73 from the nomogram, all patients could be divided into two groups, and the differences in 2-year CIR, disease-free survival (DFS), and overall survival (OS) between these two groups were significant (p < 0.05). Taken together, the results of our study indicate that gene mutations could help to predict the outcomes of patients with AML receiving allotransplantation.

Low Soluble Programmed Cell Death Protein 1 Levels After Allogeneic Stem Cell Transplantation Predict Moderate or Severe Chronic GvHD and Inferior Overall Survival

Programmed cell death protein-1 (PD-1) is an inhibitory co-receptor required for regulating immune responsiveness and maintaining immune homeostasis. As PD-1 can be released as bioactive soluble molecule, we investigated the clinical significance of soluble PD-1 (sPD-1) after allogeneic hematopoietic stem cell transplantation (HSCT) regarding graft-versus-host disease (GvHD), relapse, and overall survival (OS) in a mono-centric cohort of 82 patients. Compared to pre-HSCT and to healthy controls, post-HSCT sPD-1 plasma levels were significantly increased during an observation time of three months. Univariate analysis revealed that low sPD-1 plasma levels at month one, two or three post HSCT were associated with acute GvHD grade III-IV, the onset of moderate/severe chronic GvHD (cGvHD) and inferior OS, DFS, and TRM, respectively. No relationship was detected to relapse rates. sPD-1 plasma levels were significantly increased in ATG-treated patients compared to ATG-untreated patients. Multivariate analysis revealed that a low sPD-1 plasma levels status at one or two month(s) after HSCT is an independent indicator for inferior OS, DFS, or TRM. A low sPD-1 plasma levels status at month three post HSCT is predictive for the onset of moderate/severe cGvHD. Thus, our study pinpoints the soluble inhibitory co-receptor PD-1 as a promising candidate molecule for the prediction of clinical HSCT outcome.

Pretransplantation EASIX predicts intensive care unit admission in allogeneic hematopoietic cell transplantation

The Endothelial Activation and Stress Index (EASIX) is a laboratory-based prognosis index defined as creatinine × lactate dehydrogenase/platelets. When measured at pretransplantation evaluation (EASIX-PRE), it predicts allogeneic hematopoietic cell transplantation (alloHCT) mortality. This study explores its ability to predict intensive care unit (ICU) admission and validates EASIX-PRE predictive power for overall survival (OS) and nonrelapse mortality (NRM) in 167 consecutive patients undergoing alloHCT. EASIX-PRE was calculated retrospectively in all patients and transformed into log2 values (log2-EASIX-PRE). Log2-EASIX-PRE predicted ICU admission (hazard ratio [HR], 1.41; P < .001), OS (HR, 1.19; P = .011), and NRM (HR, 1.28; P = .004). The most discriminating EASIX-PRE cutoff value for risk of ICU admission was the 75th percentile (2.795); for OS and NRM, it was the median value (1.703). Patients with EASIX-PRE >2.795 had higher incidence of ICU admission in comparison with patients with lower EASIX-PRE values (day +180, 35.8% vs 12.8%; HR, 2.28; P = .010). Additionally, patients with EASIX-PRE >1.073 had lower OS (2 years, 57.7% vs 68.7%; HR, 1.98; P = .006) and higher NRM (2 years, 38.7% vs 18.5%; HR, 2.92; P = .001) than patients with lower EASIX-PRE results. Log2-EASIX-PRE was not associated with incidence of transplantation-associated microangiopathy, sinusoidal obstruction syndrome, or acute graft-versus-host disease. This study proposes EASIX-PRE as a prognostic tool to identify patients undergoing alloHCT at increased risk of severe organ dysfunction and who would therefore require ICU admission. Early identification of patients at high risk of severe events could contribute to personalized intervention design. Additionally, it validates the association between EASIX-PRE and OS and NRM in those undergoing alloHCT.

Post-Irradiation Hyperamylasemia Is a Prognostic Marker for Allogeneic Hematopoietic Stem Cell Transplantation Outcomes in Pediatric Population: A Retrospective Single-Centre Cohort Analysis

Background: Total body irradiation (TBI) is a mandatory step for patients with acute lymphoblastic leukemia (ALL), undergoing allogeneic hematopoietic stem cell transplantation (HSCT). In the past, amylases have been reported to be a possible sign of TBI toxicity. We investigated the relationship between total amylases (TA) and transplant-related outcomes in pediatric recipients. Methods: We retrospectively analyzed the medical records of all the patients who underwent allogeneic HSCT between January 2000 and November 2019. The inclusion criteria were the following: recipient’s age between 2 and 18, diagnosis of ALL, no previous transplantation, and use of TBI-based conditioning. The serum total amylase and pancreatic amylase were evaluated before, during, and after transplantation. Cytokines and chemokines assays were retrospectively performed. Results: 78 patients fulfilled the inclusion criteria. Fifty-seven patients were treated with fractionated TBI, and 21 with a single-dose regimen. The overall survival (OS) was 62.8%. Elevated values of TA were detected in 71 patients (91%). The TA were excellent in predicting the OS (AUC = 0.773; 95% CI = 0.66–0.86; p < 0.001). TA values below 374 U/L were correlated with a higher OS. The highest mean TA values (673 U/L) were associated with a high disease-progression mortality rate. The TA showed a high predictive performance for disease progression-related death (AUC = 0.865; 95% CI = 0.77–0.93; p < 0.0001). Elevated TA values were also connected with significantly higher levels of proinflammatory cytokines, such as TNF-α, IL-6, and RANTES (p < 0.001). Conclusions: this study shows that TA is a valuable predictor of post-transplant OS and increased risk of leukemia relapse.

Impact of risk scores in outcome of patients with myeloid neoplasms after allogeneic stem cell transplant

BACKGROUND

The main causes of failure of allogeneic hematopoietic stem cell transplantation (allo-transplant) in patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are relapse and transplant-related mortality. Different scores have been designed to predict the prognosis of these patients. The objective of this study was to assess which score or combination has better outcome predictive capacity.

METHODS

Retrospective analysis of patients with AML and MDS who received a first peripheral blood allo-transplant in a single center, between December 2001 and October 2019. Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI), European Group for Blood and Marrow Transplantation (EBMT) and Disease Risk Index (DRI) scores were calculated. For each score and for the HCT-CI/DRI and HCT-CI/EBMT combinations, overall survival (OS), cumulative incidence of relapse (CIR), non-relapse-related mortality (NRM), and graft versus host disease-free relapse-free survival (GRFS) were analyzed.

RESULTS

175 patients were evaluated. With a median (range) follow-up of 3.96 (0.32-17.22) years, the 5-year probabilities (95% CI) of OS, CIR, NRM, and GRFS were 36% (28%-44%), 28% (21%-35%), 38% (30%-46%) and 24% (17%-31%), respectively. For OS, only the DRI score selected two groups with statistically significant differences (DRI 0-1: 41% vs. DRI ≥2: 24%; p=0.011). The combination of DRI 0-1 and HCT-CI 0-2 showed OS probabilities of 45% vs. 26% for those with DRI 0-1 and HCT-CI ≥3; p=0.041.

CONCLUSIONS

In patients with AML and MDS submitted to allo-transplant, the combination of HCT-CI and DRI scores provided the best stratification for OS.

Hematopoietic Cell Transplant-Composite Risk (HCT-CR): A Novel Predictor of Prognosis in Acute Leukemia Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HCT) is a curable treatment modality for hematologic disorders. Transplant-related mortality remains high despite prominent scientific and technologic improvements. In consideration with the potential impact of patient- and disease-related factors on transplant outcome, this retrospective study was performed to investigate the predictive role of pretransplant HCT-composite risk (HCT-CR) score in allo-HCT recipients.

METHODS

A total of 313 patients with acute leukemia (male/female: 192/121; median age, 36 [18-71] years) were included in this study. The study cohort was divided into 2 subgroups based on pretransplant HCT-CR categories. The HCT-CR^lo group included low-risk patients, and the HCT-CR^int-hi group consisted of intermediate-, high-, and very high-risk patients.

RESULTS

In the whole cohort, overall survival (OS) and 5-year OS were found to be 32.2% and 45.1%, respectively. Probability of OS was significantly better in the HCT-CR^lo group compared with the HCT-CR^int-hi group (P < .001). Leukemia-free survival (LFS) and 3-year LFS were 59.5% and 65.1%, respectively. Probability of LFS was better in the HCT-CR^lo group compared with the HCT-CR^int-hi group (P = .001). Nonrelapse mortality (NRM) and 3-year NRM were estimated to be 38.1% and 27.5%, respectively. Probability of NRM was significantly higher in the HCT-CR^int-hi group compared with the HCT-CR^lo group (P = .012). In multivariate analysis, HCT-CR was shown to have significant prognostic impact in acute lymphoblastic leukemia patients (P = .023; hazard ratio, 2.613; 95% CI, 1.142-5.982).

CONCLUSION

Pretransplant evaluation of patient- and disease-related factors is essential for the accurate prediction of posttransplant survival. Further efforts to evolve current criteria for pretransplant risk assessment would eventuate in better transplant outcomes.

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.

Optimizing Transplant Approaches and Post-Transplant Strategies for Patients With Acute Myeloid Leukemia

Acute Myeloid Leukemia (AML) is the commonest indication for allogeneic stem cell transplantation (allo-SCT) worldwide. The increasingly important role of allo-SCT in the management of AML has been underpinned by two important advances. Firstly, improvements in disease risk stratification utilizing genetic and Measurable Residual Disease (MRD) technologies permit ever more accurate identification of allo-mandatory patients who are at high risk of relapse if treated by chemotherapy alone. Secondly, increased donor availability coupled with the advent of reduced intensity conditioning (RIC) regimens has substantially expanded transplant access for patients with high risk AML In patients allografted for AML disease relapse continues to represent the commonest cause of transplant failure and the development of novel strategies with the potential to reduce disease recurrence represents a major unmet need.

Development and validation of a disease risk stratification system for patients with haematological malignancies: a retrospective cohort study of the European Society for Blood and Marrow Transplantation registry

BACKGROUND

Diagnosis and remission status at the time of allogeneic haematopoietic stem-cell transplantation (HSCT) are the principal determinants of overall survival following transplantation. We sought to develop a contemporary disease-risk stratification system (DRSS) that accounts for heterogeneous transplantation indications.

METHODS

In this retrospective cohort study we included 55 histology and remission status combinations across haematological malignancies, including acute leukaemia, lymphoma, multiple myeloma, and myeloproliferative and myelodysplastic disorders. A total of 47 265 adult patients (aged ≥18 years) who received an allogeneic HSCT between Jan 1, 2012, and Dec 31, 2016, and were reported to the European Society for Blood and Marrow Transplantation registry were included. We divided EBMT patients into derivation (n=25 534), tuning (n=18 365), and geographical validation (n=3366) cohorts. Disease combinations were ranked in a multivariable Cox regression for overall survival in the derivation cohort, cutoff for risk groups were evaluated for the tuning cohort, and the selected system was tested on the geographical validation cohort. An independent single-centre US cohort of 660 patients transplanted between Jan 1, 2010, and Dec 31, 2015 was used to externally validate the results.

FINDINGS

The DRSS model stratified patients in the derivation cohort (median follow-up was 2·1 years [IQR 1·0-3·2]) into five risk groups with increasing mortality risk: low risk (reference group), intermediate-1 (hazard ratio for overall survival 1·26 [95% CI 1·17-1·36], p<0·0001), intermediate-2 (1·53 [1·42-1·66], p<0·0001), high (2·03 [1·86-2·22], p<0·0001), and very high (2·87 [2·63-3·13], p<0·0001). DRSS levels were also associated with a stepwise increase in risk across the tuning and geographical validation cohort. In the external validation cohort (median follow-up was 5·7 years [IQR 4·5-7·1]), the DRSS scheme separated patients into 4 risk groups associated with increasing risk of mortality: intermediate-2 risk (hazard ratio [HR] 1·34 [95% CI 1·04-1·74], p=0·025), high risk (HR 2·03 [95% CI 1·39-2·95], p=0·00023) and very-high risk (HR 2·26 [95% CI 1·62-3·15], p<0·0001) patients compared with the low risk and intermediate-1 risk group (reference group). Across all cohorts, between 64% and 65% of patients were categorised as having intermediate-risk disease by a previous prognostic system (ie, the disease-risk index [DRI]). The DRSS reclassified these intermediate-risk DRI patients, with 855 (6%) low risk, 7111 (51%) intermediate-1 risk, 5700 (41%) intermediate-2 risk, and 375 (3%) high risk or very high risk of 14 041 patients in a subanalysis combining the tuning and internal geographic validation cohorts. The DRI projected 2-year overall survival was 62·1% (95% CI 61·2-62·9) for these 14 041 patients, while the DRSS reclassified them into finer prognostic groups with overall survival ranging from 45·7% (37·4-54·0; very high risk patients) to 73·1% (70·1-76·2; low risk patients).

INTERPRETATION

The DRSS is a novel risk stratification tool including disease features related to histology, genetic profile, and treatment response. The model should serve as a benchmark for future studies. This system facilitates the interpretation and analysis of studies with heterogeneous cohorts, promoting trial-design with more inclusive populations.

FUNDING

The Varda and Boaz Dotan Research Center for Hemato-Oncology Research, Tel Aviv University.