Improved outcome of children transplanted for high-risk leukemia by using a new strategy of cyclosporine-based GVHD prophylaxis

New Perspectives on Primary Prophylaxis of Invasive Fungal Infection in Children Undergoing Hematopoietic Stem Cell Transplantation: A 10-Year Retrospective Cohort Study

Background: Allogenic hematopoietic stem cell transplantation (a-HCT) remains a therapeutic treatment for many pediatric hematological diseases. The occurrence of invasive fungal infections (IFIs) is a complication for which ECIL-8 recommends primary antifungal prophylaxis. In this study, we evaluated the impact of our local strategy of not systematically administering primary antifungal prophylaxis in children undergoing a-HCT on the occurrence and mortality of IFIs. Methods: We performed a retrospective monocentric study from 2010 to 2020. We retained all proven and probable IFIs diagnosed during the first year post a-HCT. Results: 308 patients were included. Eighteen patients developed twenty IFIs (thirteen proven, seven probable) (6.5%) among which aspergillosis (n = 10, 50%) and candidosis (n = 7, 35%) were the most frequently diagnosed infections. Only 2% of children died because of an IFI, which represents 14% of all deaths. Multivariate analysis found that age > 10 years (OR: 0.29), the use of a therapeutic antiviral treatment (OR: 2.71) and a low neutrophil count reconstitution (OR: 0.93) were significantly associated with the risk of IFI occurrence. There was also a trend of malignant underlying disease and status ≥ CR2 but it was not retained in multivariate analysis. Conclusions: IFI occurrence was not higher in our cohort than what is reported in the literature with the use of systematic antifungal prophylaxis, with a good survival rate nonetheless. Thus, a prophylaxis could be considered for children with a high risk of IFI such as those aged over 10 years.

Impact on Outcome of Minimal Residual Disease after Hematopoietic Stem Cell Transplantation with Fludarabine, Amsacrine, and Cytosine Arabinoside-Busulfan Conditioning: A Retrospective Monocentric Study

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) after conditioning with a sequential association of fludarabine, amsacrine, and cytosine arabinoside (FLAMSA) followed by a reduced-intensity conditioning regimen has emerged for patients with high-risk acute myeloid leukemia (AML), especially in refractory or relapsing patients. Here we aimed to address retrospectively the impact of pretransplantation minimal residual disease (MRD) by flow cytometry on the outcomes of high-risk AML patients who underwent allo-HSCT after sequential FLAMSA-busulfan (FLAMSA-Bu)-based conditioning regimens. We included 165 high-risk AML patients who underwent transplantation after FLAMSA-BU in this retrospective single-center "real life" study. All patients received in vivo T cell depletion with antithymocyte globulin (5 mg/kg). MRD detection was based on a leukemia-associated immunophenotype using the European LeukemiaNet recommendations, with a threshold of .1%. Univariate and multivariate analyses were performed using R version 4.1.1 (R Foundation for Statistical Computing, Vienna, Austria). With a median follow-up of 4.0 years post-transplantation, the median overall survival (OS) was 54.9 months. Overall, 41 patients (24.8%) relapsed post-transplantation, with a resulting cumulative incidence of relapse (CIR) of 26.7% at 2 years and 34.0% at 5 years. Detectable MRD preceding allo-HSCT and refractory status were associated with worse median OS and CIR rates compared with patients without detectable MRD; however, OS was not significantly different between pre-HSCT MRD-positive and refractory patients (median, .7 year versus 2.0 years; P = .3). Conversely, pre-HSCT MRD negativity was associated with a reduced 2-year CIR. Neither European LeukemiaNet risk stratification nor age had a significant influence on OS. In the multivariate analysis, only pre-HSCT MRD positivity and lower conditioning regimen intensity were significantly associated with a poorer OS. The cumulative incidence of extensive chronic graft-versus-host disease at 2 years was 26.15%. The estimated nonrelapse mortality (NRM) of the entire cohort at 2 years was 23.1%, with age and unrelated donor identified as risk factors for higher NRM. Our data ahow that FLAMSA-Bu conditioning did not reverse the pejorative effect of detectable pre-HSCT MRD, suggesting that such patients should be offered alternative strategies before HSCT to reach deeper remission.

Beyond steroids: A systematic review and proposed solutions to managing acute graft-versus-host disease in adolescents and young adults

The outcomes of allogeneic hematopoietic cell transplantation (HCT) in adolescents and young adults (AYAs) with hematologic malignancies have been shown to be poorer when compared to results in children, due to a combination of higher relapse rates and greater treatment-related mortality (TRM). Although differences in relapse risk have been studied extensively, toxicity has been examined and reported less often. In this systematic review, we summarize recently published studies that have examined the differences in rates of TRM and acute graft-versus-host disease (GVHD) in AYAs and children with hematologic malignancies, and attempt to explain why these disparities exist and how they impact outcomes. In addition, we present best practices for management of steroid-refractory GVHD that are likely to improve survival in this patient population. Further, we propose the development of personalized, risk-based approaches for the prevention and treatment of GVHD that incorporate novel platforms and interventions. We believe this individualized approach is likely to reduce toxicity and greatly improve outcomes for this vulnerable population.

Impact of a Bayesian Individualization of Cyclosporine Dosage Regimen for Children Undergoing Allogeneic Hematopoietic Cell Transplantation: A Cost-Effectiveness Analysis

BACKGROUND

Cyclosporine A (CsA) is the main drug used to prevent graft-versus-host disease in patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). CsA therapeutic drug monitoring (TDM) has been performed for ages, with studies revealing clinical benefits, but failing to examine its economic impact. In this article, the main objective was to evaluate the economic impact of the CsA TDM strategy, based on a Bayesian approach, by assessing costs related to its clinical impact. Furthermore, TDM effectiveness was analyzed for pharmacokinetics and clinical outcomes.

METHODS

A cost-effective, nonrandomized, retrospective, single-center study compared 2 CsA monitoring and dose adaptation strategies in pediatric patients undergoing HSCT. From 2014 to 2016, CsA TDM was performed using a population pharmacokinetics model-coupled Bayesian approach by a pharmacist ["pharmacist-assisted individualization" (PAI)]. From 2017 to 2018, CsA TDM was performed by the clinician without a Bayesian approach (non-PAI group). HSCT costs were evaluated from the French National Insurance perspective. Economic and clinical outcomes were assessed by measuring incremental cost-effectiveness ratios.

RESULTS

The study included 144 patients: 90 and 54 patients in PAI and non-PAI groups, respectively. Both groups were comparable for sociodemographic and clinical characteristics. The mean total cost per patient was significantly lower (P < 0.01) in the PAI group (€85,947) than in the non-PAI group (€100,435). Multivariate analysis revealed that TDM based on the Bayesian approach was a protective factor (odds ratio = 0.86) for severe acute graft-versus-host disease. We noted that pharmacist-based TDM was the dominant strategy. Bayesian method-based TDM allowed an increase in the percentage of target attainment at any period post-HSCT.

CONCLUSIONS

CsA TDM with a Bayesian approach is a cost-effective procedure, and highlighted clinical benefits encourage the development of new TDM strategies for HSCT.

Impact of measurable residual disease by decentralized flow cytometry: a PETHEMA real-world study in 1076 patients with acute myeloid leukemia

The role of decentralized assessment of measurable residual disease (MRD) for risk stratification in acute myeloid leukemia (AML) remains largely unknown, and so it does which methodological aspects are critical to empower the evaluation of MRD with prognostic significance, particularly if using multiparameter flow cytometry (MFC). We analyzed 1076 AML patients in first remission after induction chemotherapy, in whom MRD was evaluated by MFC in local laboratories of 60 Hospitals participating in the PETHEMA registry. We also conducted a survey on technical aspects of MRD testing to determine the impact of methodological heterogeneity in the prognostic value of MFC. Our results confirmed the recommended cutoff of 0.1% to discriminate patients with significantly different cumulative-incidence of relapse (-CIR- HR:0.71, P < 0.001) and overall survival (HR: 0.73, P = 0.001), but uncovered the limited prognostic value of MFC based MRD in multivariate and recursive partitioning models including other clinical, genetic and treatment related factors. Virtually all aspects related with methodological, interpretation, and reporting of MFC based MRD testing impacted in its ability to discriminate patients with different CIR. Thus, this study demonstrated that "real-world" assessment of MRD using MFC is prognostic in patients at first remission, and urges greater standardization for improved risk-stratification toward clinical decisions in AML.

A Clinical Decision Support Tool to Find the Best Initial Intravenous Cyclosporine Regimen in Pediatric Hematopoietic Stem Cell Transplantation

To optimize cyclosporine A (CsA) dosing regimen in pediatric patients undergoing hematopoietic stem cell transplantation (HSCT), we aimed to provide clinicians with a validated decision support tool for determining the most suitable first dose of intravenous CsA. We used a 10-year monocentric data set of pediatric patients undergoing HSCT. Discretization of all variables was performed according to literature or thanks to algorithms using Shannon entropy (from information theory) or equal width intervals. The first 8 years were used to build the Bayesian network model. This model underwent a 10-fold cross-validation, and then a prospective validation with data of the last 2 years. There were 3.3% and 4.1% of missing values in the training and the validation data set, respectively. After prospective validation, the Tree-Augmented Naïve Bayesian network shows interesting prediction performances with an average area under the receiver operating characteristic curve of 0.804, 32.8% of misclassified patients, a true-positive rate of 0.672, and a false-positive rate of 0.285. This validated model allows good predictions to propose an optimized and personalized initial CsA dose for pediatric patients undergoing HSCT. The clinical impact of its use should be further evaluated.

Current Prophylaxis and Treatment Approaches for Acute Graft-Versus-Host Disease in Haematopoietic Stem Cell Transplantation for Children With Acute Lymphoblastic Leukaemia

Acute graft-versus-host disease (aGvHD) continues to be a leading cause of morbidity and mortality following allogeneic haematopoietic stem cell transplantation (HSCT). However, higher event-free survival (EFS) was observed in patients with acute lymphoblastic leukaemia (ALL) and grade II aGvHD vs. patients with no or grade I GvHD in the randomised, controlled, open-label, international, multicentre Phase III For Omitting Radiation Under Majority age (FORUM) trial. This finding suggests that moderate-severity aGvHD is associated with a graft-versus-leukaemia effect which protects against leukaemia recurrence. In order to optimise the benefits of HSCT for leukaemia patients, reduction of non-relapse mortality-which is predominantly caused by severe GvHD-is of utmost importance. Herein, we review contemporary prophylaxis and treatment options for aGvHD in children with ALL and the key challenges of aGvHD management, focusing on maintaining the graft-versus-leukaemia effect without increasing the severity of GvHD.

A decision support tool to find the best cyclosporine dose when switching from intravenous to oral route in pediatric stem cell transplant patients

PURPOSE

Managing the pharmacokinetic variability of immunosuppressive drugs after pediatric hematopoietic stem cell transplantation (HSCT) is a clinical challenge. Thus, the aim of our study was to design and validate a decision support tool predicting the best first cyclosporine oral dose to give when switching from intravenous route.

METHODS

We used 10-years pediatric HSCT patients' dataset from 2008 to 2018. A tree-augmented naïve Bayesian network model (method belonging to artificial intelligence) was built with data from the first eight-years, and validated with data from the last two.

RESULTS

The Bayesian network model obtained showed good prediction performances, both after a 10-fold cross-validation and external validation, with respectively an AUC-ROC of 0.89 and 0.86, a percentage of misclassified patients of 28.7% and 35.2%, a true positive rate of 0.71 and 0.65, and a false positive rate of 0.12 and 0.14 respectively.

CONCLUSION

The final model allows the prediction of the most likely cyclosporine oral dose to reach the therapeutic target specified by the clinician. The clinical impact of using this model needs to be prospectively warranted. Respecting the decision support tool terms of use is necessary as well as remaining critical about the prediction by confronting it with the clinical context.

Bayesian Networks: A New Approach to Predict Therapeutic Range Achievement of Initial Cyclosporine Blood Concentration After Pediatric Hematopoietic Stem Cell Transplantation

BACKGROUND

Pediatric hematopoietic stem cell transplantation (HSCT) allows the treatment of numerous diseases, both malignant and non-malignant. Cyclosporine, a narrow therapeutic index drug, is the major immunosuppressant used to prevent graft-versus-host disease (GVHD), but may also cause severe adverse effects in case of overdosing.

OBJECTIVE

The objective of this study is to predict the initial cyclosporine residual blood concentration value after pediatric HSCT, and consequently the dose necessary to reach the therapeutic range, using a mathematical individual predictive model.

METHODS

Clinical and biological data collected from the graft infusion for 2 months after transplantation in 155 pediatric patients undergoing HSCT between 2008 and 2016 were used to generate synthetic data for 1000 subjects which were used to build a Bayesian network model. We compared the characteristics and sensitivity to clinical or biological missing data of this model with four other methods.

RESULTS

The tree-augmented Naïve Bayesian network showed the best characteristics, with no missing data (area under the curve of the receiving operator characteristics curve [AUC-ROC] of 0.89 ± 0.02), 18.9 ± 2.6% of patients misclassified, and positive and negative predictive values of 85.9 ± 3.4% and 74.2 ± 5.1%, respectively, and this trend is found in the synthetic dataset from no to 10% missing data. The most relevant variables that could influence whether the initial residual cyclosporine concentration is in the therapeutic range are the last dose before measurement and the mean dose before measurement.

CONCLUSIONS

We developed and cross-validated an online Bayesian network to predict the first cyclosporine concentration after pediatric HSCT. This model allows simulation of different dosing regimens, and enables the best dosing regimen to reach the therapeutic range immediately after transplantation to be found, minimizing the risk of adverse effects and GVHD occurrence.

Relationship between cyclosporine area-under-the curve and acute graft versus host disease in pediatric patients undergoing hematopoietic stem cell transplant: A prospective, multicenter study

Traditionally in hematopoietic stem cell transplant (HSCT), cyclosporine doses are individualized using cyclosporine trough concentrations (C₀) while area under the concentration vs time curve (AUC) is used in solid organ transplant. AUC potentially has an important relationship with the development of acute graft-versus-host-disease (aGVHD). We conducted a prospective study to describe the relationship between severe (grade III-IV) aGVHD and cyclosporine AUC in pediatric HSCT recipients. Pediatric patients who underwent allogeneic myeloablative HSCT and scheduled to receive cyclosporine for aGVHD prophylaxis participated in this multicenter study. Cyclosporine doses were adjusted based on C₀ according to each center's standard of care. Cyclosporine AUC was determined weekly until neutrophil engraftment or Day +42, whichever was later. Associations between severe aGVHD and cyclosporine AUC and other patient and treatment-related factors were evaluated. Of the 110 children enrolled, 97 were evaluable. Thirty-seven (38%) children developed aGVHD; 13 (13.4%) had severe aGVHD. On univariate analysis, there was no association between severe aGVHD and cyclosporine AUC at any time point before engraftment. Future research should focus on refinement of C₀ targets for cyclosporine therapeutic drug monitoring in HSCT.

Outcomes of matched sibling donor bone marrow transplantation in children using single-agent calcineurin inhibitors as prophylaxis for graft versus host disease

BACKGROUND

Optimal graft versus host disease (GVHD) prophylaxis prevents severe manifestations without excess immunosuppression. Standard prophylaxis includes a calcineurin inhibitor (CNI) with low-dose methotrexate. However, single-agent CNI may be sufficient prophylaxis for a defined group of patients. Single-agent CNI has been used for GVHD prophylaxis for human leukocyte antigen (HLA)-matched sibling donor (MSD) bone marrow transplants (BMTs) in young patients at the Children's Hospital of Philadelphia for over 20 years. Here, we describe outcomes using this prophylactic strategy in a recent cohort.

PROCEDURE

We performed a single-institution chart review and retrospective analysis of consecutive children undergoing MSD BMT who received single-agent CNI for GVHD prophylaxis between January 2002 and December 2014.

RESULTS

Fifty-two children with a median age of 6.1 years (interquartile range [IQR] 2.5-8.3) and donor age of 6 years (IQR 3-10), with malignant and nonmalignant diseases (n = 35 and 17, respectively) were evaluated. Forty-three (82.6%) received oral prophylaxis with single-agent tacrolimus after initial intravenous therapy. Rates of GVHD were consistent with reported rates on dual prophylaxis: the overall incidence of grades 2-4 acute GVHD was 25.5%, grades 3-4 GVHD 9.8%, and chronic GVHD 10.4%. The cumulative incidence of relapse among children with malignancy was 20% at a median of 237 days (IQR 194-318) post-transplant. Two-year overall survival was 82.7% (95% confidence interval [CI]: 69.4-90.6%) and event-free survival was 78.9% (95% CI: 65.1-87.7%). No patient experienced graft failure.

CONCLUSIONS

Single-agent CNI is a safe, effective approach to GVHD prophylaxis in young patients undergoing HLA-identical sibling BMT. Additionally, single-agent oral tacrolimus is a reasonable alternative to cyclosporine in this population.

Influence of Age on Acute and Chronic GVHD in Children Undergoing HLA-Identical Sibling Bone Marrow Transplantation for Acute Leukemia: Implications for Prophylaxis

Relapse remains the major cause of mortality after hematopoietic cell transplantation (HCT) for pediatric acute leukemia. Previous research has suggested that reducing the intensity of calcineurin inhibitor-based graft-versus-host disease (GVHD) prophylaxis may be an effective strategy for abrogating the risk of relapse in pediatric patients undergoing matched sibling donor (MSD) HCT. We reasoned that the benefits of this strategy could be maximized by selectively applying it to those patients least likely to develop GVHD. We conducted a study of risk factors for GVHD, to risk-stratify patients based on age. Patients age <18 years with leukemia who received myeloablative, T cell-replete MSD bone marrow transplantation and calcineurin inhibitor-based GVHD prophylaxis between 2000 and 2013 and were entered into the Center for International Blood and Marrow Transplant Research registry were included. The cumulative incidence of grade II-IV acute GVHD (aGVHD) was 19%, that of grade II-IV aGVHD 7%, and that of chronic GVHD (cGVHD) was 16%. Compared with age 13 to 18 years, age 2 to 12 years was associated with a lower risk of grade II-IV aGVHD (hazard ratio [HR], .42; 95% confidence interval [CI], .26 to .70; P = .0008), grade II-IV aGVHD (HR, .24; 95% CI, .10 to .56; P = .001), and cGVHD (HR, .32; 95% CI, .19 to .54; P < .001). Compared with 2000-2004, the risk of grade II-IV aGVHD was lower in children undergoing transplantation in 2005-2008 (HR, .36; 95% CI, .20 to .65; P = .0007) and in 2009-2013 (HR, .24; 95% CI. .11 to .53; P = .0004). Similarly, the risk of grade III-IV aGVHD was lower in children undergoing transplantation in 2005-2008 (HR, .23; 95% CI, .08 to .65; P = .0056) and 2009-2013 (HR, .16; 95% CI, .04 to .67; P = .0126) compared with those doing so in 2000-2004. We conclude that aGVHD rates have decreased significantly over time, and that children age 2 to 12 years are at very low risk for aGVHD and cGVHD. These results should be validated in an independent analysis, because these patients with high-risk malignancies may be good candidates for trials of reduced GVHD prophylaxis.

Minimal residual disease prior to allogeneic hematopoietic cell transplantation in acute myeloid leukemia: a meta-analysis

Minimal residual disease prior to allogeneic hematopoietic cell transplantation has been associated with increased risk of relapse and death in patients with acute myeloid leukemia, but detection methodologies and results vary widely. We performed a systematic review and meta-analysis evaluating the prognostic role of minimal residual disease detected by polymerase chain reaction or multiparametric flow cytometry before transplant. We identified 19 articles published between January 2005 and June 2016 and extracted hazard ratios for leukemia-free survival, overall survival, and cumulative incidences of relapse and non-relapse mortality. Pre-transplant minimal residual disease was associated with worse leukemia-free survival (hazard ratio=2.76 [1.90-4.00]), overall survival (hazard ratio=2.36 [1.73-3.22]), and cumulative incidence of relapse (hazard ratio=3.65 [2.53-5.27]), but not non-relapse mortality (hazard ratio=1.12 [0.81-1.55]). These associations held regardless of detection method, conditioning intensity, and patient age. Adverse cytogenetics was not an independent risk factor for death or relapse. There was more heterogeneity among studies using flow cytometry-based than WT1 polymerase chain reaction-based detection (I²=75.1% vs. <0.1% for leukemia-free survival, 67.8% vs. <0.1% for overall survival, and 22.1% vs. <0.1% for cumulative incidence of relapse). These results demonstrate a strong relationship between pre-transplant minimal residual disease and post-transplant relapse and survival. Outcome heterogeneity among studies using flow-based methods may underscore site-specific methodological differences or differences in test performance and interpretation.