Persistent MRD before and after allogeneic BMT predicts relapse in children with acute lymphoblastic leukaemia

Intensified conditioning regimens with total marrow irradiation/etoposide/cyclophosphamide and busulfan/etoposide/cyclophosphamide overcome the impact of pre-transplant minimal residual disease on outcomes in high-risk acute lymphoblastic leukemia patients in complete remission

PURPOSE

Among high-risk acute lymphoblastic leukemia (ALL) patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT), those with positive minimal residual disease (MRD) are susceptible to poor outcomes. Therefore, it is necessary to determine the most suitable preparatory regimen for these patients.

METHODS

Data were analyzed from 141 patients who received allo-HSCT and were diagnosed with high-risk ALL. These patients underwent intensified conditioning regimens, including either total marrow and lymphoid irradiation (TMLI)-etoposide (VP16)-cyclophosphamide (CY) or busulfan (BU)-VP16-CY between October 2016 and November 2022. A total of 141 individuals were in complete remission (CR) before transplantation and, among all patients, 90 individuals exhibited a negative MRD status and 51 patients had a positive MRD status.

RESULTS

In patients who tested negative for MRD, the incidence of relapse within a 2-year timeframe was 25.0% (24.8%-25.5%), compared with 32.2% (31.2%-33.2%) in MRD-positive patients; however, this difference was not statistically significant. There were no significant differences in the 2-year disease-free survival (DFS) and 2-year overall survival (OS) rates between the MRD-negative and MRD-positive groups (DFS: 67.2% (57.9%-78.1%) vs. 55.5% (42.6%-72.3%); OS: 69.0% (61.9%-88.2%) vs. 66.7% (53.9%-82.5%)). Furthermore, no notable variations were observed in the occurrence of transplant-related mortality (TRM) and graft-versus-host disease (GVHD) across the two groups.

CONCLUSION

This study reveals the benefits of TMLI-VP16-CY and BU-VP16-CY conditioning regimens in high-risk ALL patients with CR and MRD-positive status. A large-scale prospective clinical trial is warranted in the future.

Anlotinib exerts an anti-T-cell acute lymphoblastic leukemia effect in vitro and in vivo

BACKGROUND

Despite some progress having been made regarding the treatment of T-cell acute lymphoblastic leukemia (T-ALL), the prognosis of T-ALL, particularly adult T-ALL, is still poor. Identifying novel, effective anti-T-ALL drugs is of great significance. Anlotinib, an oral tyrosine kinase inhibitor currently utilized in the treatment of lung cancer, exhibited a promising anti-T-ALL effect. A comprehensive study should therefore be conducted to explore both the in vitro as well as in vivo mechanisms of the anti-T-ALL effects of anlotinib.

METHODS

CCK8 assays and flow cytometry were employed to investigate the viability, cell cycle distribution, and apoptosis of T-ALL cell lines when treated with anlotinib. T-ALL xenograft mouse models were established to examine the in vivo antileukemic effects of anlotinib. Cellular and molecular analysis of T-ALL were conducted to define the underlying mechanisms.

RESULTS

In vitro, anlotinib significantly inhibited the viability, induced G2/M phase arrest and apoptosis in T-ALL cell lines in a concentration-dependent pattern. In vivo, anlotinib also demonstrated a strong anti-tumor effect at doses that are well-tolerated. Interestingly, anlotinib could decrease the protein levels of the intracellular domains of NOTCH1 (ICN1) and c-Myc, two important targets for T-ALL. Mechanistically, anlotinib-induced c-Myc reduction was associated with proteasome-mediated degradation, while the ICN1 reduction was not due to protein degradation or transcriptional repression.

CONCLUSIONS

The present study showed that anlotinib may be a promising anti-T-ALL candidate drug, and simultaneous reduction of the protein levels of both ICN1 and c-Myc may contribute to the anti-T-ALL efficacy of anlotinib.

Immunophenotypic measurable residual disease monitoring in adult acute lymphoblastic leukemia patients undergoing allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) offers a survival benefit to adult patients affected by acute lymphoblastic leukemia (ALL). However, to avoid an overt disease relapse, patients with pre or post transplant persistence or occurrence of measurable residual disease (MRD) may require cellular or pharmacological interventions with eventual side effects. While the significance of multiparametric flow cytometry (MFC) in the guidance of ALL treatment in both adult and pediatric patients is undebated, fewer data are available regarding the impact of MRD monitoring, as assessed by MFC analysis, in the allo-HSCT settings. Aim of this article is to summarize and discuss currently available information on the role of MFC detection of MRD in adult ALL patients undergoing allo-HSCT. The significance of MFC-based MRD according to sensitivity level, timing, and in relation to molecular techniques of MRD and chimerism assessment will be also discussed.

Measurable residual disease analysis in paediatric acute lymphoblastic leukaemia patients with ABL-class fusions

Background

ABL-class fusions including NUP214-ABL1 and EBF1-PDGFRB occur in high risk acute lymphoblastic leukaemia (ALL) with gene expression patterns similar to BCR-ABL-positive ALL. Our aim was to evaluate new DNA-based measurable residual disease (MRD) tests detecting these fusions and IKZF1-deletions in comparison with conventional immunoglobulin/T-cell receptor (Ig/TCR) markers.

Methods

Precise genomic breakpoints were defined from targeted or whole genome next generation sequencing for ABL-fusions and BCR-ABL1. Quantitative PCR assays were designed and used to re-measure MRD in remission bone marrow samples previously tested using Ig/TCR markers. All MRD testing complied with EuroMRD guidelines.

Results

ABL-class patients had 46% 5year event-free survival and 79% 5year overall survival. All had sensitive fusion tests giving high concordance between Ig/TCR and ABL-class fusion results (21 patients, n = 257 samples, r2 = 0.9786, P < 0.0001) and Ig/TCR and IKZF1-deletion results (9 patients, n = 143 samples, r2 = 0.9661, P < 0.0001). In contrast, in BCR-ABL1 patients, Ig/TCR and BCR-ABL1 tests were discordant in 32% (40 patients, n = 346 samples, r2 = 0.4703, P < 0.0001) and IKZF1-deletion results were closer to Ig/TCR (25 patients, n = 176, r2 = 0.8631, P < 0.0001).

Conclusions

MRD monitoring based on patient-specific assays detecting gene fusions or recurrent assays for IKZF1-deletions is feasible and provides good alternatives to Ig/TCR tests to monitor MRD in ABL-class ALL.

Recent Advances in Treatment Options for Childhood Acute Lymphoblastic Leukemia

Simple Summary

Acute lymphoblastic leukemia is the most common blood cancer in pediatric patients. Despite the enormous progress in ALL treatment, which is reflected by a high 5-year overall survival rate that reaches up to 96% in the most recent studies, there are still patients that cannot be saved. Treatment of ALL is based on conventional methods, including chemotherapy and radiotherapy. These methods carry with them the risk of very high toxicities. Severe complications related to conventional therapies decrease their effectiveness and can sometimes lead to death. Therefore, currently, numerous studies are being carried out on novel forms of treatment. In this work, classical methods of treatment have been summarized. Furthermore, novel treatment methods and the possibility of combining them with chemotherapy have been incorporated into the present work. Targeted treatment, CAR-T-cell therapy, and immunotherapy for ALL have been described. Treatment options for the relapse/chemoresistance ALL have been presented.

Abstract

Acute lymphoblastic leukemia is the most common blood cancer in pediatric patients. There has been enormous progress in ALL treatment in recent years, which is reflected by the increase in the 5-year OS from 57% in the 1970s to up to 96% in the most recent studies. ALL treatment is based primarily on conventional methods, which include chemotherapy and radiotherapy. Their main weakness is severe toxicity, which prompts dose reduction, decreases the effectiveness of the treatment, and, in some cases, can lead to death. Currently, numerous modifications in treatment regimens are applied in order to limit toxicities emerging from conventional approaches and improve outcomes. Hematological treatment of pediatric patients is reaching for more novel treatment options, such as targeted treatment, CAR-T-cells therapy, and immunotherapy. These methods are currently used in conjunction with chemotherapy. Nevertheless, the swift progress in their development and increasing efficacity can lead to applying those novel therapies as standalone therapeutic options for pediatric ALL.

Clinical Value of Measurable Residual Disease in Acute Lymphoblastic Leukemia

Measurable (minimal) residual disease (MRD) status in acute lymphoblastic leukemia (ALL) has largely superseded the importance of traditional risk factors for ALL, such as baseline white blood cell count, cytogenetics, and immunophenotype, and has emerged as the most powerful independent prognostic predictor. The development of sensitive MRD techniques, such as multicolor flow cytometry (MFC), quantitative polymerase chain reaction (PCR), and next-generation sequencing (NGS), may further improve risk stratification and expand its impact in therapy. Additionally, the availability of highly effective agents for MRD eradication, such as blinatumomab, inotuzumab ozogamicin, and chimeric antigen receptor (CAR) T-cell therapies, enabled the development of frontline regimens capable of eradicating MRD early in the treatment course. While long-term follow-up of this approach is lacking, it has the potential to significantly reduce the need for intensive post-remission treatments, including allogeneic bone marrow transplantation, in a significant proportion of patients with ALL.

Correlation between a 10-color flow cytometric measurable residual disease (MRD) analysis and molecular MRD in adult B-acute lymphoblastic leukemia

BACKGROUND

Measurable residual disease (MRD) monitoring in acute lymphoblastic leukemia (ALL) is an important predictive factor for patient outcome and treatment intensification. Molecular monitoring, particularly with quantitative polymerase chain reaction (qPCR) to measure immunoglobin heavy or kappa chain (Ig) or T-cell receptor (TCR) gene rearrangements, offers high sensitivity but accessibility is limited by expertise, cost, and turnaround time. Flow cytometric assays are cheaper and more widely available, and sensitivity is improved with multi-parameter flow cytometry at eight or more colors.

METHODS

We developed a 10-color single tube flow cytometry assay. Samples were subject to bulk ammonium chloride lysis to maximize cell yields with a target of 1 × 10⁶ events. Once normal maturation patterns were established, patient samples were analyzed in parallel to standard molecular monitoring.

RESULTS

Flow cytometry was performed on 114 samples. An informative immunophenotype was identifiable in all 22 patients who had a diagnostic sample. MRD analysis was performed on 87 samples. The median lower limits of detection and quantification were 0.004% (range 0.0005%-0.028%) and 0.01% (range 0.001%-0.07%) respectively. Sixty-five samples had concurrent molecular MRD testing, with good correlation (r = 0.83, p < 0.001). Results were concordant in 52 samples, and discordant in 13 samples, including one case where impending relapse was detected by flow cytometry but not Ig/TCR qPCR.

CONCLUSIONS

Our 10-color flow cytometric MRD assay provided adequate sensitivity and good correlation with molecular assays. This technique offers rapid and affordable testing in B-ALL patients, including cases where a suitable molecular assay cannot be developed or has reduced sensitivity.

Novel Treatments for Pediatric Relapsed or Refractory Acute B-Cell Lineage Lymphoblastic Leukemia: Precision Medicine Era

With the markedly increased cure rate for children with newly diagnosed pediatric B-cell acute lymphoblastic leukemia (B-ALL), relapse and refractory B-ALL (R/R B-ALL) remain the primary cause of death worldwide due to the limitations of multidrug chemotherapy. As we now have a more profound understanding of R/R ALL, including the mechanism of recurrence and drug resistance, prognostic indicators, genotypic changes and so on, we can use newly emerging technologies to identify operational molecular targets and find sensitive drugs for individualized treatment. In addition, more promising and innovative immunotherapies and molecular targeted drugs that are expected to kill leukemic cells more effectively while maintaining low toxicity to achieve minimal residual disease (MRD) negativity and better bridge hematopoietic stem cell transplantation (HSCT) have also been widely developed. To date, the prognosis of pediatric patients with R/R B-ALL has been enhanced markedly thanks to the development of novel drugs. This article reviews the new advancements of several promising strategies for pediatric R/R B-ALL.

An MRD-stratified pediatric protocol is as deliverable in adolescents and young adults as in children with ALL

Pediatric regimens have improved outcomes in adolescent and young adult (AYA) acute lymphoblastic leukemia (ALL). However, results remain inferior to children with ALL. The Australasian Leukaemia and Lymphoma Group (ALLG) ALL06 study (anzctr.org.au/ACTRN12611000814976) was designed to assess whether a pediatric ALL regimen (Australian and New Zealand Children's Haematology and Oncology Group [ANZCHOG] Study 8) could be administered to patients aged 15 to 39 years in a comparable time frame to children as assessed by the proportion of patients completing induction/consolidation and commencing the next phase of therapy (protocol M or high-risk [HR] treatment) by day 94. Minimal residual disease (MRD) response stratified patients to HR treatment and transplantation. From 2012 to 2018, a total of 86 patients were enrolled; 82 were eligible. Median age was 22 years (range, 16-38 years). Induction/consolidation was equally deliverable in ALL06 as in Study 8. In ALL06, 41.5% (95% confidence interval [CI], 30.7-52.9) commenced protocol M or HR therapy by day 94 vs 39.3% in Study 8 (P = .77). Median time to protocol M/HR treatment was 96 days (interquartile range, 87.5-103 days) in ALL06 vs 98 days in Study 8 (P = .80). Induction mortality was 3.6%. With a median follow-up of 44 months (1-96 months), estimated 3-year disease-free survival was 72.8% (95% CI, 62.8-82.7), and estimated 3-year overall survival was 74.9% (95% CI, 65.3-84.5). End induction/consolidation MRD negativity rate was 58.6%. Body mass index ≥30 kg/m2 and day 79 MRD positivity were associated with poorer disease-free survival and overall survival. Pediatric therapy was safe and as deliverable in AYA patients as in children with ALL. Intolerance of pediatric ALL induction/consolidation is not a major contributor to inferior outcomes in AYA ALL.

Total Body Irradiation in Haematopoietic Stem Cell Transplantation for Paediatric Acute Lymphoblastic Leukaemia: Review of the Literature and Future Directions

Total body irradiation (TBI) has been a pivotal component of the conditioning regimen for allogeneic myeloablative haematopoietic stem cell transplantation (HSCT) in very-high-risk acute lymphoblastic leukaemia (ALL) for decades, especially in children and young adults. The myeloablative conditioning regimen has two aims: (1) to eradicate leukaemic cells, and (2) to prevent rejection of the graft through suppression of the recipient's immune system. Radiotherapy has the advantage of achieving an adequate dose effect in sanctuary sites and in areas with poor blood supply. However, radiotherapy is subject to radiobiological trade-offs between ALL cell destruction, immune and haematopoietic stem cell survival, and various adverse effects in normal tissue. To diminish toxicity, a shift from single-fraction to fractionated TBI has taken place. However, HSCT and TBI are still associated with multiple late sequelae, leaving room for improvement. This review discusses the past developments of TBI and considerations for dose, fractionation and dose-rate, as well as issues regarding TBI setup performance, limitations and possibilities for improvement. TBI is typically delivered using conventional irradiation techniques and centres have locally developed heterogeneous treatment methods and ways to achieve reduced doses in several organs. There are, however, limitations in options to shield organs at risk without compromising the anti-leukaemic and immunosuppressive effects of conventional TBI. Technological improvements in radiotherapy planning and delivery with highly conformal TBI or total marrow irradiation (TMI), and total marrow and lymphoid irradiation (TMLI) have opened the way to investigate the potential reduction of radiotherapy-related toxicities without jeopardising efficacy. The demonstration of the superiority of TBI compared with chemotherapy-only conditioning regimens for event-free and overall survival in the randomised For Omitting Radiation Under Majority age (FORUM) trial in children with high-risk ALL makes exploration of the optimal use of TBI delivery mandatory. Standardisation and comprehensive reporting of conventional TBI techniques as well as cooperation between radiotherapy centres may help to increase the ratio between treatment outcomes and toxicity, and future studies must determine potential added benefit of innovative conformal techniques to ultimately improve quality of life for paediatric ALL patients receiving TBI-conditioned HSCT.

Intensive monitoring of minimal residual disease and chimerism after allogeneic hematopoietic stem cell transplantation for acute leukemia in children

Posttransplant leukemia detection before overt relapse is key to the success of immunotherapeutic interventions, as they are more efficient when leukemia burden is low. However, optimal schedule and monitoring methods are not well defined. We report the intensive bone marrow monitoring of minimal residual disease (MRD) using flow cytometry (FC) and nested reverse transcription polymerase chain reaction (RT-PCR) whenever a fusion transcript allowed it and chimerism by PCR at 11 timepoints in the first 2 years after transplant. Seventy-one transplants were performed in 59 consecutive children, for acute myeloid (n = 38), lymphoid (n = 31), or mixed-phenotype (n = 2) leukemia. MRD was monitored in 62 cases using FC (n = 58) and/or RT-PCR (n = 35). Sixty-seven percent of leukemia recurrences were detected before overt relapse, with a detection rate of 89% by RT-PCR and 40% by FC alone. Increased mixed chimerism was never the first evidence of recurrence. Two patients monitored by RT-PCR relapsed without previous MRD detection, one after missed scheduled evaluation and the other 4.7 years post transplant. Among the 22 cases with MRD detection without overt relapse, 19 received therapeutic interventions. Eight (42%) never relapsed. In conclusion, intensive marrow monitoring by RT-PCR effectively allows for early detection of posttransplant leukemia recurrence.

Whole-genome sequencing facilitates patient-specific quantitative PCR-based minimal residual disease monitoring in acute lymphoblastic leukaemia, neuroblastoma and Ewing sarcoma

Background

Minimal residual disease (MRD) measurement is a cornerstone of contemporary acute lymphoblastic leukaemia (ALL) treatment. The presence of immunoglobulin (Ig) and T cell receptor (TCR) gene recombinations in leukaemic clones allows widespread use of patient-specific, DNA-based MRD assays. In contrast, paediatric solid tumour MRD remains experimental and has focussed on generic assays targeting tumour-specific messenger RNA, methylated DNA or microRNA.

Methods

We examined the feasibility of using whole-genome sequencing (WGS) data to design tumour-specific polymerase chain reaction (PCR)-based MRD tests (WGS-MRD) in 18 children with high-risk relapsed cancer, including ALL, high-risk neuroblastoma (HR-NB) and Ewing sarcoma (EWS) (n = 6 each).

Results

Sensitive WGS-MRD assays were generated for each patient and allowed quantitation of 1 tumour cell per 10⁻⁴ (0.01%)–10^–5 (0.001%) mononuclear cells. In ALL, WGS-MRD and Ig/TCR-MRD were highly concordant. WGS-MRD assays also showed good concordance between quantitative PCR and droplet digital PCR formats. In serial clinical samples, WGS-MRD correlated with disease course. In solid tumours, WGS-MRD assays were more sensitive than RNA-MRD assays.

Conclusions

WGS facilitated the development of patient-specific MRD tests in ALL, HR-NB and EWS with potential clinical utility in monitoring treatment response. WGS data could be used to design patient-specific MRD assays in a broad range of tumours.

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.

Epigenetic analysis of patients with T-ALL identifies poor outcomes and a hypomethylating agent-responsive subgroup

Adult "T cell" acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy that is associated with poor outcomes, requiring additional therapeutic options. The DNA methylation landscapes of adult T-ALL remain undercharacterized. Here, we systematically analyzed the DNA methylation profiles of normal thymic-sorted T cell subpopulations and 143 primary adult T-ALLs as part of the French GRAALL 2003-2005 trial. Our results indicated that T-ALL is epigenetically heterogeneous consisting of five subtypes (C₁-C₅), which were either associated with co-occurring DNA methyltransferase 3 alpha (DNMT3A)/isocitrate dehydrogenase [NADP(+)] 2 (IDH2) mutations (C₁), TAL bHLH transcription factor 1, erythroid differentiation factor (TAL1) deregulation (C₂), T cell leukemia homeobox 3 (TLX3) (C₃), TLX1/in cis-homeobox A9 (HOXA9) (C₄), or in trans-HOXA9 overexpression (C₅). Integrative analysis of DNA methylation and gene expression identified potential cluster-specific oncogenes and tumor suppressor genes. In addition to an aggressive hypomethylated subgroup (C₁), our data identified an unexpected subset of hypermethylated T-ALL (C₅) associated with poor outcome and primary therapeutic response. Using mouse xenografts, we demonstrated that hypermethylated T-ALL samples exhibited therapeutic responses to the DNA hypomethylating agent 5-azacytidine, which significantly (survival probability; P = 0.001 for C₃, 0.01 for C₄, and 0.0253 for C₅) delayed tumor progression. These findings suggest that epigenetic-based therapies may provide an alternative treatment option in hypermethylated T-ALL.

Predictive Value of Dynamic Peri-Transplantation MRD Assessed By MFC Either Alone or in Combination with Other Variables for Outcomes of Patients with T-Cell Acute Lymphoblastic Leukemia

We performed a retrospective analysis to investigate dynamic peri-hematopoietic stem cell transplantation (HSCT) minimal/measurable residual disease (MRD) on outcomes in patients with T-cell acute lymphoblastic leukemia (T-ALL). A total of 271 patients were enrolled and classified into three groups: unchanged negative MRD pre- and post-HSCT group (group A), post-MRD non-increase group (group B), and post-MRD increase group (group C). The patients in group B and group C experienced a higher cumulative incidence of relapse (CIR) (42% vs. 71% vs. 16%, P<0.001) and lower leukemia-free survival (LFS) (46% vs. 21% vs. 70%, P<0.001) and overall survival (OS) (50% vs. 28% vs. 72%, P<0.001) than in group A, but there was no significant difference in non-relapse mortality (NRM) among three groups (14% vs. 12% vs. 8%, P=0.752). Multivariate analysis showed that dynamic peri-HSCT MRD was associated with CIR (HR=2.392, 95% CI, 1.816-3.151, P<0.001), LFS (HR=1.964, 95% CI, 1.546-2.496, P<0.001) and OS (HR=1.731, 95% CI, 1.348-2.222, P<0.001). We also established a risk scoring system based on dynamic peri-HSCT MRD combined with remission status pre-HSCT and onset of chronic graft-versus-host disease (GVHD). This risk scoring system could better distinguish CIR (c=0.730) than that for pre-HSCT MRD (c=0.562), post-HSCT MRD (c=0.616) and pre- and post-MRD dynamics (c=0.648). Our results confirm the outcome predictive value of dynamic peri-HSCT MRD either alone or in combination with other variables for patients with T-ALL.

Factors Associated with Costs in Chimeric Antigen Receptor T-Cell Therapy for Patients with Relapsed/Refractory B-Cell Malignancies

Background:

Chimeric antigen receptor T cells (CAR-Ts) constitute a novel therapeutic strategy for relapsed/refractory B-cell malignancies. CAR-T therapy has been extensively applied in the clinical setting; however, few systematic studies have evaluated the cost of CAR-T treatment. This study was conducted to evaluate the total cost and cost structure of CAR-T therapy and identify potential risk factors leading to increased costs.

Methods:

We identified the associated risk factors in 89 patients in a phase 1/2 study. The cohort included patients with acute lymphoblastic leukemia (ALL, n = 55) and non-Hodgkin’s lymphoma (NHL, n = 34).

Results:

Overall, the treatment of the ALL cohort was costlier than that of the NHL cohort (P < 0.001). Furthermore, in the ALL cohort, it was costlier to treat patients with a high tumor burden (P < 0.001), high cytokine release syndrome (CRS) grade (P < 0.001), and complications of infection after CAR-T cell infusion (CTI) in the whole cohort (P = 0.013) than patients with a low tumor burden, with low CRS grade, and without infection, respectively. CRS grade and length of stay (P ≤ 0.005) were independent risk factors associated with the total cost in both the ALL and NHL cohorts during CAR-T therapy. A high tumor burden, duration of fever, and treatment with tocilizumab were independent risk factors associated with the total cost in the ALL cohort (P < 0.05).

Conclusions:

CAR-T treatment should be extended to patients with a low tumor burden or patients in a state of complete remission, and a corticosteroid approach, as opposed to tocilizumab, may reduce costs.

Unmanipulated haploidentical hematopoietic stem cell transplantation is an excellent option for children and young adult relapsed/refractory Philadelphia chromosome-negative B-cell acute lymphoblastic leukemia after CAR-T-cell therapy

Although chimeric antigen receptor T-cell (CAR-T) therapy produces a high complete remission rate among patients with relapsed/refractory B-cell acute lymphoblastic leukemia, relapse remains an urgent issue. It is uncertain whether consolidative haploidentical-allogeneic hematopoietic stem cell transplantation (haplo-HSCT) is suitable for achieving sustainable remission. Therefore, we aimed to assess the efficacy and safety of bridging CAR-T therapy to haplo-HSCT. Fifty-two patients with relapsed/refractory Philadelphia chromosome-negative B-cell acute lymphoblastic leukemia who underwent haplo-HSCT after CAR-T therapy were analyzed. The median time from CAR-T therapy to haplo-HSCT was 61 days. After a median follow-up of 24.6 months, the 1-year probabilities of event-free survival, overall survival, and cumulative incidence of relapse were 80.1% (95% confidence interval (CI), 69.0-90.9), 92.3% (95% CI, 85.0-99.5), and 14.1% (95% CI, 10.7-17.4), respectively, while the corresponding 2-year probabilities were 76.0% (95% CI, 64.2-87.7), 84.3% (95% CI, 74.3-94.3), and 19.7% (95% CI, 15.3-24.0), respectively. No increased risk of 2-year cumulative incidence of graft-versus-host disease, treatment-related mortality, or infection was observed. A pre-HSCT measurable residual disease-positive status was an independent factor associated with poor overall survival (hazard radio: 4.201, 95% CI: 1.034-17.063; P = 0.045). Haplo-HSCT may be a safe and effective treatment strategy to improve event-free survival and overall survival after CAR-T therapy.

A risk score system for stratifying the risk of relapse in B cell acute lymphocytic leukemia patients after allogenic stem cell transplantation

BACKGROUND

For patients with B cell acute lymphocytic leukemia (B-ALL) who underwent allogeneic stem cell transplantation (allo-SCT), many variables have been demonstrated to be associated with leukemia relapse. In this study, we attempted to establish a risk score system to predict transplant outcomes more precisely in patients with B-ALL after allo-SCT.

METHODS

A total of 477 patients with B-ALL who underwent allo-SCT at Peking University People's Hospital from December 2010 to December 2015 were enrolled in this retrospective study. We aimed to evaluate the factors associated with transplant outcomes after allo-SCT, and establish a risk score to identify patients with different probabilities of relapse. The univariate and multivariate analyses were performed with the Cox proportional hazards model with time-dependent variables.

RESULTS

All patients achieved neutrophil engraftment, and 95.4% of patients achieved platelet engraftment. The 5-year cumulative incidence of relapse (CIR), overall survival (OS), leukemia-free survival (LFS), and non-relapse mortality were 20.7%, 70.4%, 65.6%, and 13.9%, respectively. Multivariate analysis showed that patients with positive post-transplantation minimal residual disease (MRD), transplanted beyond the first complete remission (≥CR2), and without chronic graft-versus-host disease (cGVHD) had higher CIR (P  < 0.001, P = 0.004, and P  < 0.001, respectively) and worse LFS (P  < 0.001, P = 0.017, and P  < 0.001, respectively), and OS (P  < 0.001, P = 0.009, and P  < 0.001, respectively) than patients without MRD after transplantation, transplanted in CR1, and with cGVHD. A risk score for predicting relapse was formulated with the three above variables. The 5-year relapse rates were 6.3%, 16.6%, 55.9%, and 81.8% for patients with scores of 0, 1, 2, and 3 (P  < 0.001), respectively, while the 5-year LFS and OS values decreased with increasing risk score.

CONCLUSION

This new risk score system might stratify patients with different risks of relapse, which could guide treatment.

Minimal Residual Disease Prior to and After Haematopoietic Stem Cell Transplantation in Children and Adolescents With Acute Lymphoblastic Leukaemia: What Level of Negativity Is Relevant?

Minimal residual disease (MRD) assessment plays a central role in risk stratification and treatment guidance in paediatric patients with acute lymphoblastic leukaemia (ALL). As such, MRD prior to haematopoietic stem cell transplantation (HSCT) is a major factor that is independently correlated with outcome. High burden of MRD is negatively correlated with post-transplant survival, as both the risk of leukaemia recurrence and non-relapse mortality increase with greater levels of MRD. Despite growing evidence supporting these findings, controversies still exist. In particular, it is still not clear whether multiparameter flow cytometry and real-time quantitative polymerase chain reaction, which is used to recognise immunoglobulin and T-cell receptor gene rearrangements, can be employed interchangeably. Moreover, the higher sensitivity in MRD quantification offered by next-generation sequencing techniques may further refine the ability to stratify transplant-associated risks. While MRD quantification from bone marrow prior to HSCT remains the state of the art, heavily pre-treated patients may benefit from additional staging, such as using ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography to detect focal residues of disease. Additionally, the timing of MRD detection (i.e., immediately before administration of the conditioning regimen or weeks before) is a matter of debate. Pre-transplant MRD negativity has previously been associated with superior outcomes; however, in the recent For Omitting Radiation Under Majority age (FORUM) study, pre-HSCT MRD positivity was associated with neither relapse risk nor survival. In this review, we discuss the level of MRD that may require pre-transplant therapy intensification, risking time delay and complications (as well as losing the window for HSCT if disease progression occurs), as opposed to an adapted post-transplant strategy to achieve long-term remission. Indeed, MRD monitoring may be a valuable tool to guide individualised treatment decisions, including tapering of immunosuppression, cellular therapies (such as donor lymphocyte infusions) or additional immunotherapy (such as bispecific T-cell engagers or chimeric antigen receptor T-cell therapy).

Total Body Irradiation Forever? Optimising Chemotherapeutic Options for Irradiation-Free Conditioning for Paediatric Acute Lymphoblastic Leukaemia

Total-body irradiation (TBI) based conditioning prior to allogeneic hematopoietic stem cell transplantation (HSCT) is generally regarded as the gold-standard for children >4 years of age with acute lymphoblastic leukaemia (ALL). Retrospective studies in the 1990's suggested better survival with irradiation, confirmed in a small randomised, prospective study in the early 2000's. Most recently, this was reconfirmed by the early results of the large, randomised, international, phase III FORUM study published in 2020. But we know survivors will suffer a multitude of long-term sequelae after TBI, including second malignancies, neurocognitive, endocrine and cardiometabolic effects. The drive to avoid TBI directs us to continue optimising irradiation-free, myeloablative conditioning. In chemotherapy-based conditioning, the dominant myeloablative effect is provided by the alkylating agents, most commonly busulfan or treosulfan. Busulfan with cyclophosphamide is a long-established alternative to TBI-based conditioning in ALL patients. Substituting fludarabine for cyclophosphamide reduces toxicity, but may not be as effective, prompting the addition of a third agent, such as thiotepa, melphalan, and now clofarabine. For busulfan, it's wide pharmacokinetic (PK) variability and narrow therapeutic window is well-known, with widespread use of therapeutic drug monitoring (TDM) to individualise dosing and control the cumulative busulfan exposure. The development of first-dose selection algorithms has helped achieve early, accurate busulfan levels within the targeted therapeutic window. In the future, predictive genetic variants, associated with differing busulfan exposures and toxicities, could be employed to further tailor individualised busulfan-based conditioning for ALL patients. Treosulfan-based conditioning leads to comparable outcomes to busulfan-based conditioning in paediatric ALL, without the need for TDM to date. Future PK evaluation and modelling may optimise therapy and improve outcome. More recently, the addition of clofarabine to busulfan/fludarabine has shown encouraging results when compared to TBI-based regimens. The combination shows activity in ALL as well as AML and deserves further evaluation. Like busulfan, optimization of chemotherapy conditioning may be enhanced by understanding not just the PK of clofarabine, fludarabine, treosulfan and other agents, but also the pharmacodynamics and pharmacogenetics, ideally in the context of a single disease such as ALL.

Co-operation of ABT-199 and gemcitabine in impeding DNA damage repair and inducing cell apoptosis for synergistic therapy of T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is a high-risk subtype of acute lymphoblastic leukemia with limited therapeutic options available. Here, we evaluated the therapeutic potential of the combination of the Bcl-2 antagonist ABT-199 and cytotoxic agent gemcitabine in T-ALL cell lines. Our results showed that the combination of ABT-199 and gemcitabine exhibited synergistic cytotoxicity and induced significant apoptosis in human T-ALL cell lines (Jurkat and Molt4). The augmented apoptosis induced by combination treatment was accompanied by the greater extent of mitochondrial depolarization and enhanced DNA damage. Importantly, single agent induced DNA damage alone but did not inhibit RAD51/BRCA1-mediated repair for DNA double-strand breaks. In contrast, the combination of ABT-199 and gemcitabine disrupted RAD51/BRCA1-dependent DNA repair and remarkably activated caspase-3 and PARP to trigger apoptosis. Moreover, ABT-199 exerted an antagonistic action towards Bcl-2 and Bcl-xL, but to a certain extent moderately increased Mcl-1 level that could be compromised by gemcitabine. In conclusion, our study showed that the combination of ABT-199 and gemcitabine exhibited synergistic cytotoxicity in T-ALL cells by cooperatively targeting DNA damage repair pathway and Bcl-2 family proteins.

Addition of Thiotepa to Total Body Irradiation and Cyclophosphamide Conditioning for Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Acute Lymphoblastic Leukemia

Total body irradiation (TBI)/cyclophosphamide (CY) is a standard-of-care conditioning regimen in allogeneic hematopoietic stem cell transplant (HSCT) for pediatric acute lymphoblastic leukemia (ALL). This study sought to identify whether the addition of thiotepa (TT) to TBI/CY improves HSCT outcomes for pediatric patients with ALL. A retrospective analysis was performed on 347 pediatric ALL patients who underwent HSCT between 1995 and 2015, with 242 receiving TBI/CY/TT and 105 patients receiving TBI/CY. There were no statistical differences in age, donor source, or complete remission status between the 2 groups. Comparison of the TBI/CY/TT versus TBI/CY groups demonstrated no difference in transplant-related mortality at 1 (11% versus 11%), 5 (13% versus 16%), or 10 years (16% versus 16%). There was lower relapse in the TBI/CY/TT group at 1 (14% versus 26%), 5 (24% versus 36%), 10 (26% versus 37%), and 15 years (26% versus 37%) (P= .02) but was not statistically significant on multivariate analysis. The TBI/CY/TT group showed a trend toward improved disease-free survival (DFS) at 5 (59% versus 47%), 10 (56% versus 46%), and 15 years (49% versus 40%) (P = .05) but was not statistically significant on multivariate analysis. Comparing overall survival at 5 (62% versus 53%), 10 (57% versus 50%), and 15 years (50% versus 44%) demonstrated no statistical difference between the 2 groups. The addition of thiotepa to TBI/CY demonstrated no increase in transplant-related mortality for pediatric ALL HSCT but was unable to demonstrate significant benefit in disease control. Minimal residual disease status remained the key risk factor impacting both relapse and DFS. More studies are warranted to better clarify the benefits of using thiotepa in conditioning for ALL HSCT.

Different Effects of Pre-transplantation Measurable Residual Disease on Outcomes According to Transplant Modality in Patients With Philadelphia Chromosome Positive ALL

Background: This study compared the effects of pre-transplantation measurable residual disease (pre-MRD) on outcomes in Philadelphia chromosome (Ph)-positive ALL patients who underwent human leukocyte antigen-matched sibling donor transplantation (MSDT) or who received unmanipulated haploidentical SCT (haplo-SCT). Methods: A retrospective study (n = 202) was performed. MRD was detected by RT-PCR and multiparameter flow cytometry. Results: In the total patient group, patients with positive pre-MRD had a higher 4-year cumulative incidence of relapse (CIR) than that in patients with negative pre-MRD (26.1% vs. 12.1%, P = 0.009); however, the cumulative incidence of non-relapse mortality (NRM) (7.4% vs. 15.9%, P = 0.148), probability of leukemia-free survival (LFS) (66.3% vs. 71.4%, P = 0.480), and overall survival (OS) (68.8% vs. 76.5%, P = 0.322) were comparable. In the MSDT group, patients with positive pre-MRD had increased 4-year CIR (56.4% vs. 13.8%, P < 0.001) and decreased 4-year LFS (35.9% vs. 71.0%, P = 0.024) and OS (35.9% vs. 77.6%, P = 0.011) compared with those with negative pre-MRD. In haplo-SCT settings, the 4-year CIR (14.8% vs. 10.7%, P = 0.297), NRM (7.3% vs. 16.3%, P = 0.187) and the 4-year probability of OS (77.7% vs. 72.3%, P = 0.804) and LFS (80.5% vs. 75.7%, P = 0.660) were comparable between pre-MRD positive and negative groups. In subgroup patients with positive pre-MRD, haplo-SCT had a lower 4-year CIR (14.8% vs. 56.4%, P = 0.021) and a higher 4-year LFS (77.7% vs. 35.9%, P = 0.036) and OS (80.5% vs. 35.9%, P = 0.027) than those of MSDT. Multivariate analysis showed that haplo-SCT was associated with lower CIR (HR, 0.288; P = 0.031), superior LFS (HR, 0.283; P = 0.019) and OS (HR, 0.252; P = 0.013) in cases with a positive pre-MRD subgroup. Conclusions: Our results indicate that the effects of positive pre-MRD on the outcomes of patients with Ph-positive ALL are different according to transplant modality. For Ph-positive cases with positive pre-MRD, haplo-SCT might have strong graft-vs.-leukemia (GVL) effects.

Evaluation and management of measurable residual disease in acute lymphoblastic leukemia

With standard chemotherapy regimens for adults with acute lymphoblastic leukemia, approximately 90% of patients achieve complete remission. However, up to half of patients have persistent minimal/measurable residual disease (MRD) not recognized by routine microscopy, which constitutes the leading determinant of relapse. Many studies in pediatric and adult populations have demonstrated that achievement of MRD negativity after induction chemotherapy or during consolidation is associated with significantly better long-term outcomes, and MRD status constitutes an independently prognostic marker, often superseding other conventional risk factors. Persistence of MRD after intensive chemotherapy is indicative of treatment refractoriness and warrants alternative therapeutic approaches including allogeneic stem cell transplantation, blinatumomab, or investigational therapies such as inotuzumab ozogamicin or chimeric antigen receptor T cells. Furthermore, the incorporation of novel monoclonal antibodies or potent BCR-ABL1 tyrosine kinase inhibitors, such as ponatinib into frontline treatment may have the advantage of achieving higher rates of MRD negativity while minimizing chemotherapy-related toxicities. Many studies are therefore ongoing to determine whether this strategy can improve cure rates without the need for allogeneic stem cell transplantation.

The Genetics and Mechanisms of T-Cell Acute Lymphoblastic Leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy derived from early T-cell progenitors. The recognition of clinical, genetic, transcriptional, and biological heterogeneity in this disease has already translated into new prognostic biomarkers, improved leukemia animal models, and emerging targeted therapies. This work reviews our current understanding of the molecular mechanisms of T-ALL.

Prognosis of haploidentical hematopoietic stem cell transplantation in non-infant children with t(v;11q23)/MLL-rearranged B-cell acute lymphoblastic leukemia

B-cell acute lymphoblastic leukemia (B-ALL) with MLL-rearrangements (MLL-r) is rare in pediatric patients (aged >1 year), and optimal treatment strategies remain unclear. This study aimed to retrospectively evaluate the clinical characteristics, outcomes, and effects of allogeneic hematopoietic stem cell transplantation (allo-HSCT) of 37 non-infant children with t(v;11q23)/MLL-r B-ALL. Their 4-year overall survival (OS), event-free survival (EFS), and cumulative incidence of relapse (CIR) were 69.8 %, 58.2 %, and 39.1 %, respectively, and differed significantly between patients receiving allo-HSCT (18/19 cases received haploidentical [haplo]-HSCT) at the first complete remission (HSCT at CR1, n = 19; 87.4 %, 89.5 % and 5.3 %) and those continuing consolidation therapy (Non-HSCT at CR1, n = 18; 52.2 %, 25.9 %, and 74.1 %, respectively), and the p values were 0.022, <0.001 and <0.001, respectively. Of the 13 patients experiencing relapse during consolidation chemotherapy, the five continuing with chemotherapy only died within 44 months, and the eight patients opting for allo-HSCT after CR2 had a 4-year OS of 57.1 %. Multivariate analysis revealed HSCT at CR1 as the only independent protective factor for OS, EFS, and CIR. The present results indicate that allo-HSCT (especially haplo-HSCT) at CR1 may decrease the relapse rate and improve the prognosis of non-infant children with t(v;11q23)/MLL-r B-ALL.

Pediatric-inspired protocols in adult acute lymphoblastic leukemia: are the results bearing fruit?

Observational findings demonstrating improved survival for younger adults following pediatric, as opposed to adult, acute lymphoblastic leukemia (ALL) regimens have been translated into international, prospective multicenter clinical trials testing the pediatric regimen in young adult ALL. The results of these studies confirm the feasibility of delivering the pediatric regimen in the adult oncology setting and establish the superiority of this approach relative to historical adult cooperative group regimen results. Specific toxicities, including thrombosis, hepatotoxicity, and osteonecrosis, are more prevalent in adults receiving the pediatric regimen relative to young children. Persistent minimal residual disease (MRD) is a strong prognostic indicator in adults receiving the pediatric regimen; sensitive, high-quality MRD evaluation should be performed in all patients receiving these therapies. Incorporation of targeted agents, particularly in the frontline and MRD+ setting, will usher in the next era of the pediatric regimen in adult ALL.

How I diagnose and manage Philadelphia chromosome-like acute lymphoblastic leukemia

Advances in our understanding of mechanisms of leukemogenesis and driver mutations in acute lymphoblastic leukemia (ALL) lead to a more precise and informative sub-classification, mainly of B-cell ALL. In parallel, in recent years, novel agents have been approved for the therapy of B-cell ALL, and many others are in active clinical research. Among the newly recognized disease subtypes, Philadelphia-chromosome-like ALL is the most heterogeneous and thus, diagnostically challenging. Given that this subtype of B-cell ALL is associated with a poorer prognosis, improvement of available therapeutic approaches and protocols is a burning issue. Herein, we summarize, in a clinically relevant manner, up-to-date information regarding diagnostic strategies developed for the identification of patients with Philadelphia-chromosome-like ALL. Common therapeutic dilemmas, presented as several case scenarios, are also discussed. It is currently acceptable that patients with B-cell ALL, treated with an aim of cure, irrespective of their age, be evaluated for a Philadelphia-chromosome-like signature as early as possible. Following Philadelphia-chromosome-like recognition, a higher risk of resistance or relapse must be realized and treatment should be modified based on the patient’s specific genetic driver and clinical features. However, while active targeted therapeutic options are limited, there is much more to do than just prescribe a matched inhibitor to the identified mutated driver genes. In this review, we present a comprehensive evidence-based approach to the diagnosis and management of Philadelphia-chromosome-like ALL at different time-points during the disease course.

Transplantation in Children and Adolescents with Acute Lymphoblastic Leukemia from a Matched Donor versus an HLA-Identical Sibling: Is the Outcome Comparable? Results from the International BFM ALL SCT 2007 Study

Eligibility criteria for hematopoietic stem cell transplantation (HSCT) in acute lymphoblastic leukemia (ALL) vary according to disease characteristics, response to treatment, and type of available donor. As the risk profile of the patient worsens, a wider degree of HLA mismatching is considered acceptable. A total of 138 children and adolescents who underwent HSCT from HLA-identical sibling donors (MSDs) and 210 who underwent HSCT from matched donors (MDs) (median age, 9 years; 68% male) in 10 countries were enrolled in the International-BFM ALL SCT 2007 prospective study to assess the impact of donor type in HSCT for pediatric ALL. The 4-year event-free survival (65 ± 5% vs 61 ± 4%; P = .287), overall survival (72 ± 4% versus 68 ± 4%; P = .235), cumulative incidence of relapse (24 ± 4% versus 25 ± 3%; P = .658) and nonrelapse mortality (10 ± 3% versus 14 ± 3%; P = .212) were not significantly different between MSD and MD graft recipients. The risk of extensive chronic (cGVHD) was lower in MD graft recipients than in MSD graft recipients (hazard ratio [HR], .38; P = .002), and the risks of severe acute GVHD (aGVHD) and cGVHD were higher in peripheral blood stem cell graft recipients than in bone marrow graft recipients (HR, 2.06; P = .026). Compared with the absence of aGVHD, grade I-II aGVHD was associated with a lower risk of graft failure (HR, .63; P = .042) and grade III-IV aGVHD was associated with a higher risk of graft failure (HR, 1.85; P = .020) and nonleukemic death (HR, 8.76; P < .0001), despite a lower risk of relapse (HR, .32; P = .021). Compared with the absence of cGVHD, extensive cGVHD was associated with a higher risk of nonleukemic death (HR, 8.12; P < .0001). Because the outcomes of transplantation from a matched donor were not inferior to those of transplantation from an HLA-identical sibling, eligibility criteria for transplantation might be reviewed in pediatric ALL and possibly in other malignancies as well. Bone marrow should be the preferred stem cell source, and the addition of MTX should be considered in MSD graft recipients.

Fratricide-resistant CD1a-specific CAR T cells for the treatment of cortical T-cell acute lymphoblastic leukemia

Relapsed/refractory T-cell acute lymphoblastic leukemia (T-ALL) has a dismal outcome, and no effective targeted immunotherapies for T-ALL exist. The extension of chimeric antigen receptor (CAR) T cells (CARTs) to T-ALL remains challenging because the shared expression of target antigens between CARTs and T-ALL blasts leads to CART fratricide. CD1a is exclusively expressed in cortical T-ALL (coT-ALL), a major subset of T-ALL, and retained at relapse. This article reports that the expression of CD1a is mainly restricted to developing cortical thymocytes, and neither CD34+ progenitors nor T cells express CD1a during ontogeny, confining the risk of on-target/off-tumor toxicity. We thus developed and preclinically validated a CD1a-specific CAR with robust and specific cytotoxicity in vitro and antileukemic activity in vivo in xenograft models of coT-ALL, using both cell lines and coT-ALL patient-derived primary blasts. CD1a-CARTs are fratricide resistant, persist long term in vivo (retaining antileukemic activity in re-challenge experiments), and respond to viral antigens. Our data support the therapeutic and safe use of fratricide-resistant CD1a-CARTs for relapsed/refractory coT-ALL.

Minimal residual disease status determined by multiparametric flow cytometry pretransplantation predicts the outcome of patients with ALL receiving unmanipulated haploidentical allografts

This study evaluated the effects of pretransplantation minimal residual disease (pre-MRD) on outcomes of patients with acute lymphoblastic leukemia (ALL) who underwent unmanipulated haploidentical stem cell transplantation (haplo-SCT). A retrospective study including 543 patients with ALL was performed. MRD was determined using multiparametric flow cytometry. Both in the entire cohort of patients and in subgroup cases with T-ALL or B-ALL, patients with positive pre-MRD had a higher incidence of relapse (CIR) than those with negative pre-MRD in MSDT settings (P < 0.01 for all). Landmark analysis at 6 months showed that MRD positivity was significantly and independently associated with inferior rates of relapse (HR, 1.908; P = 0.007), leukemia-free survival (LFS) (HR, 1.559; P = 0.038), and OS (HR, 1.545; P = 0.049). The levels of pre-MRD according to a logarithmic scale were also associated with leukemia relapse, LFS, and OS, except that cases with MRD <0.01% experienced comparable CIR and LFS to those with negative pre-MRD. A risk score for CIR was developed using the variables pre-MRD, disease status, and immunophenotype of ALL. The CIR was 14%, 26%, and 59% for subjects with scores of 0, 1, and 2-3, respectively (P < 0.001). Three-year LFS was 75%, 64%, and 42%, respectively (P < 0.001). Multivariate analysis confirmed the association of the risk score with CIR and LFS. The results indicate that positive pre-MRD, except for low level one (MRD < 0.01%), is associated with poor outcomes in patients with ALL who underwent unmanipulated haplo-SCT.

Outcomes of patients with childhood B-cell precursor acute lymphoblastic leukaemia with late bone marrow relapses: long-term follow-up of the ALLR3 open-label randomised trial

BACKGROUND

The ALLR3 trial investigated outcomes of children with B-cell precursor acute lymphoblastic leukaemia who had late bone marrow relapses. We analysed long-term follow-up outcomes of these patients.

METHODS

ALLR3 was an open-label randomised clinical trial that recruited children aged 1-18 years with B-cell precursor acute lymphoblastic leukaemia who had late bone marrow relapses. Eligible patients were recruited from centres in Australia, Ireland, the Netherlands, New Zealand, and the UK. Patients were randomly assigned from Jan 31, 2003, to Dec 31, 2007, and the trial closed to recruitment on Oct 31, 2013. Randomly assigned patients were allocated to receive either idarubicin or mitoxantrone in induction by stratified concealed randomisation; after randomisation stopped in Dec 31, 2007, all patients were allocated to receive mitoxantrone. After three blocks of therapy, patients with high minimal residual disease (≥10-4 cells) at the end of induction were allocated to undergo allogeneic stem-cell transplantation and those with low minimal residual disease (<10-4 cells) at the end of induction were allocated to receive chemotherapy. Minimal residual disease level was measured by real-time quantitative PCR analysis of immunoglobulin and T-cell receptor gene rearrangements. The primary endpoint of the original ALLR3 clinical trial was progression-free survival of randomly assigned patients. The primary endpoint of this long-term follow-up analysis was progression-free survival of patients with late bone marrow relapses stratified by minimal residual disease level. Outcomes were correlated with age, site, time to recurrence, and genetic subtypes, and analysed by both intention to treat and actual treatment received. This trial is registered on the ISRCTN registry, number ISRCTN45724312, and on ClinicalTrials.gov, number NCT00967057.

FINDINGS

Between Feb 2, 2003, and Oct 28, 2013, 228 patients with B-cell precursor acute lymphoblastic leukaemia and late bone marrow relapses were treated. After a median follow-up of 84 months (IQR 48-109), progression-free survival of all randomly assigned patients was 60% (95% CI 54-70). 220 patients achieved second complete remission, and minimal residual disease was evaluable in 192 (87%). 110 patients with late bone marrow relapses and high minimal residual disease at the end of induction were allocated to undergo stem-cell transplantation, and 82 patients with low minimal residual disease at the end of induction were allocated to receive chemotherapy. In the patients allocated to undergo stem-cell transplantation, four relapses and three deaths were reported before the procedure, and 11 patients were not transplanted. Of the 92 patients transplanted, 58 (63%) remained in second complete remission, 13 (14%) died of complications, and 21 (23%) relapsed after stem-cell transplantation. In patients allocated to receive chemotherapy, one early treatment-related death was reported and 11 patients were transplanted. Of the 70 patients who continued on chemotherapy, 49 (70%) remained in second complete remission, two (3%) died of complications, and 19 (27%) relapsed. Progression-free survival at 5 years was 56% (95% CI 46-65) in those with high minimal residual disease and 72% (60-81) in patients with low minimal residual disease (p=0·0078). Treatment-related serious adverse events were not analysed in the long-term follow-up.

INTERPRETATION

Patients with B-cell precursor acute lymphoblastic leukaemia with late bone marrow relapses and low minimal residual disease at end of induction had favourable outcomes with chemotherapy without undergoing stem-cell transplantation. Patients with high minimal residual disease benefited from stem-cell transplantation, and targeted therapies might offer further improvements in outcomes for these patients.

FUNDING

Bloodwise (Formerly Leukaemia and Lymphoma Research) UK, Cancer Research UK, Sporting Chance Cancer Foundation, National Health and Medical Research Council Australia, KindreneKankervrij Netherlands, European Union Seventh Framework Programme, India Alliance Wellcome DBT Margdarshi Fellowship.

Minimal residual disease level predicts outcome in adults with Ph-negative B-precursor acute lymphoblastic leukemia

OBJECTIVES

Detectable minimal residual disease (MRD) after therapy for acute lymphoblastic leukemia (ALL) is the strongest predictor of hematologic relapse. This study evaluated outcomes of patients with B-cell precursor ALL with MRD of ≥10^-4 Methods: Study population was from ALL study groups in Europe managed in national study protocols 2000-2014. MRD was measured by polymerase chain reaction or flow cytometry. Patients were age ≥15 years at initial ALL diagnosis. Patients were excluded if exposed to blinatumomab within 18 months of baseline or prior alloHSCT.

RESULTS

Of 272 patients in CR1, baseline MRD was ≥10^-1, 10^-2 to <10^-1, 10^-3 to <10^-2, and 10^-4 to <10^-3 in 15 (6%), 71 (26%), 109 (40%), and 77 (28%) patients, respectively. Median duration of complete remission (DoR) was 18.5 months (95% confidence interval [CI], 11.9-27.2), median relapse-free survival (RFS) was 12.4 months (95% CI, 10.0-19.0) and median overall survival (OS) was 32.5 months (95% CI, 23.6-48.0). Lower baseline MRD level (P ≤ .0003) and white blood cell count <30,000/µL at diagnosis (P ≤ .0053) were strong predictors for better RFS and DoR. Allogeneic hematopoietic stem cell transplantation (alloHSCT) was associated with longer RFS (hazard ratio [HR], 0.59; 95% CI, 0.41-0.84) and DoR (HR, 0.43; 95% CI, 0.29-0.64); the association with OS was not significant (HR, 0.72; 95% CI, 0.50-1.05).

DISCUSSION

In conclusion, RFS, DoR, and OS are relatively short in patients with MRD-positive ALL, particularly at higher MRD levels. AlloHSCT may improve survival but has limitations. Alternative approaches are needed to improve outcomes in MRD-positive ALL.

Methods and role of minimal residual disease after stem cell transplantation

Relapse is the major cause of treatment failure after stem cell transplantation. Despite the fact that relapses occurred even if transplantation was performed in complete remission, it is obvious that minimal residual disease is present though not morphologically evident. Since adaptive immunotherapy by donor lymphocyte infusion or other novel cell therapies as well as less toxic drugs, which can be used after transplantation, the detection of minimal residual disease (MRD) has become a clinical important variable for outcome. Besides the increasing options to treat MRD, the most advanced technologies currently allow to detect residual malignant cells with a sensitivity of 10^-5 to 10^-6.Under the patronage of the European Society for Blood and Marrow Transplantation (EBMT) and the American Society for Blood and Marrow Transplantation (ASBMT) the 3rd workshop was held on 4/5 November 2016 in Hamburg/Germany, with the aim to present an up-to-date status of epidemiology and biology of relapse and to summarize the currently available options to prevent and treat post-transplant relapse. Here the current methods and role of minimal residual disease for myeloid and lymphoid malignancies are summarized.

Influence of pre-transplant minimal residual disease on prognosis after Allo-SCT for patients with acute lymphoblastic leukemia: systematic review and meta-analysis

BACKGROUND

This meta-analysis was performed to explore the impact of minimal residual disease (MRD) prior to transplantation on the prognosis for patients with acute lymphoblastic leukemia (ALL).

METHODS

A systematic search of PubMed, Embase, and the Cochrane Library was conducted for relevant studies from database inception to March 2016. A total of 21 studies were included.

RESULTS

Patients with positive MRD prior to allogeneic stem cell transplantation (allo-SCT) had a significantly higher rate of relapse compared with those with negative MRD (HR = 3.26; P <  0.05). Pre-transplantation positive MRD was a significant negative predictor of relapse-free survival (RFS) (HR = 2.53; P <  0.05), event-free survival (EFS) (HR = 4.77; P < 0.05), and overall survival (OS) (HR = 1.98; P < 0.05). However, positive MRD prior to transplantation was not associated with a higher rate of nonrelapse mortality.

CONCLUSIONS

Positive MRD before allo-SCT was a predictor of poor prognosis after transplantation in ALL.

TRIAL REGISTRATION

Not applicable.

Idarubicin-Intensified Hematopoietic Cell Transplantation Improves Relapse and Survival of High-Risk Acute Leukemia Patients with Minimal Residual Disease

The optimal conditioning regimen of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for high-risk patients with minimal residual disease (MRD) remains controversial. We studied the results in 98 high-risk acute leukemia patients transplanted with idarubicin (IDA)-intensified conditioning regimens between 2012 January and 2017 January. Among these patients, 31 (31.6%) had more than 5% marrow blasts at time of transplantation and 67 patients were in morphologic remission: MRD negative status at time of conditioning was achieved in 39 patients (39.8%), whereas 28 (28.6%) remained carriers of any other positive MRD level in the bone marrow. Three-year relapse estimates of patients with MRD-positive remission was 22.0%, which was remarkably lower than patients with active disease (45.4%, P = .027) but approximate to that of patients in MRD-negative remission (15.5%, P = .522). There were no significant differences in terms of 3-year estimated overall survival (OS) and disease-free survival (DFS) between MRD-positive remission and MRD-negative remission groups (71.4% versus 79.1% [P = .562] and 67.9% versus 76.9% [P = .634], respectively). Moreover, the estimated rates of 3-year OS and DFS of patients in MRD-positive remission were significantly better than those in patients with active disease (71.4% versus 41.9% [P = .033] and 67.9% versus 38.7% [P = .037], respectively). These data indicate that IDA-intensified conditioning allo-HSCT could overcome the negative prognostic impact of MRD.

[Screening and verification of key genes in T-cell acute lymphoblastic leukemia]

OBJECTIVE

To explore the key genes in T-cell acute lymphoblastic leukemia (T-ALL) using bioinformatics method to better understand the pathogenic mechanisms of T-ALL.

METHODS

The gene expression profiles of GSE14317 were obtained from Gene Expression Omnibus database. The differentially expressed genes (DEGs) in T-ALL were analyzed using R package Limma. The online analysis tool DAVID was used to perform the functional and pathway enrichment analysis. The protein-protein interaction network was constructed by STRING and visualized by Cytoscape. Based on the JASPAR database, the transcription factors (TFs) of the hub genes were obtained. RT-PCR was used to test the mRNA expression level of the key genes.

RESULTS

A total of 1443 DEGs were identified, including 800 up-regulated genes and 643 down-regulated genes. These DEGs were significantly enriched in the cell cycle, hematopoietic cell lineage, cytokine-cytokine receptor interaction and T cell receptor signaling pathway. The top 10 hub genes identified from the PPI networks included CDK1, PIK3R1, CCNB1, CCNA2, CDC20, JUN, GNG11, PLK1, PCNA and CCNB2, which were enriched in chemokine signaling pathway, ubiquition mediated proteolysis and cell cycle. In the TF-target gene network, 42 differentially expressed TFs were identified, among which ELF5, HIC2 and MEISI had binding sites with 9 of the candidate hub genes. RT-PCR showed that the mRNA expression level of all the candidate hub genes except for GNG11 were consistent with the gene expression profiles.

CONCLUSION

The hub genes CDK1, PIK3R1, CCNB1, CCNA2, CDC20, JUN, PLK1, PCNA, CCNB2, ELF5, HIC2 and MEISI participate in the occurrence of T-ALL. Our finding provides new insights into the pathogenesis of T-ALL.

Heterogeneity in mechanisms of emergent resistance in pediatric T-cell acute lymphoblastic leukemia

Relapse in pediatric T-cell acute lymphoblastic leukemia (T-ALL) remains a significant clinical problem and is thought to be associated with clonal selection during treatment. In this study we used an established pre-clinical model of induction therapy to increase our understanding of the effect of engraftment and chemotherapy on clonal selection and acquisition of drug resistance in vivo. Immune-deficient mice were engrafted with patient diagnostic specimens and exposed to a repeated combination therapy consisting of vincristine, dexamethasone, L-asparaginase and daunorubicin. Any re-emergence of disease following therapy was shown to be associated with resistance to dexamethasone, no resistance was observed to the other three drugs. Immunoglobulin/T-cell receptor gene rearrangements closely matched those in respective diagnosis and relapse patient specimens, highlighting that these clonal markers do not fully reflect the biological changes associated with drug resistance. Gene expression profiling revealed the significant underlying heterogeneity of dexamethasone-resistant xenografts. Alterations were observed in a large number of biological pathways, yet no dominant signature was common to all lines. These findings indicate that the biological changes associated with T-ALL relapse and resistance are stochastic and highly individual, and underline the importance of using sophisticated molecular techniques or single cell analyses in developing personalized approaches to therapy.

MicroRNA expression and activity in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is a lymphoid malignancy caused by the oncogenic transformation of immature T-cell progenitors. Many biologically relevant genetic and epigenetic alterations have been identified as driving factors for this transformation. Recently, microRNAs (miRNAs) have been shown to influence various leukemias, including T-ALL. Aberrant expression of miRNAs can function as either oncogenes or tumor suppressors in T-ALL through the regulation of cell migration, invasion, proliferation, apoptosis, and chemoresistance. This occurs by targeting key signaling pathways or transcriptional factors that play a critical role in T-ALL pathology and progression. Different miRNA expression profiles have been linked to specific genetic subtypes of human T-ALL. Furthermore, miRNAs can also act as independent prognostic factors to predict clinical outcomes for T-ALL patients. In the current review, we will focus on the role of miRNAs in the development and progression of T-ALL.

Association of Minimal Residual Disease With Clinical Outcome in Pediatric and Adult Acute Lymphoblastic Leukemia: A Meta-analysis

Importance

Minimal residual disease (MRD) refers to the presence of disease in cases deemed to be in complete remission by conventional pathologic analysis. Assessing the association of MRD status following induction therapy in patients with acute lymphoblastic leukemia (ALL) with relapse and mortality may improve the efficiency of clinical trials and accelerate drug development.

Objective

To quantify the relationships between event-free survival (EFS) and overall survival (OS) with MRD status in pediatric and adult ALL using publications of clinical trials and other databases.

Data Sources

Clinical studies in ALL identified via searches of PubMed, MEDLINE, and clinicaltrials.gov.

Study Selection

Our search and study screening process adhered to the PRISMA Guidelines. Studies that addressed EFS or OS by MRD status in patients with ALL were included; reviews, abstracts, and studies with fewer than 30 patients or insufficient MRD description were excluded.

Data Extraction and Synthesis

Study sample size, patient age, follow-up time, timing of MRD assessment (postinduction or consolidation), MRD detection method, phenotype/genotype (B cell, T cell, Philadelphia chromosome), and EFS and OS. Searches of PubMed and MEDLINE identified 566 articles. A parallel search on clinicaltrials.gov found 67 closed trials and 62 open trials as of 2014. Merging results of 2 independent searches and applying exclusions gave 39 publications in 3 arms of patient populations (adult, pediatric, and mixed). We performed separate meta-analyses for each of these 3 subpopulations.

Results

The 39 publications comprised 13 637 patients: 16 adult studies (2076 patients), 20 pediatric (11 249 patients), and 3 mixed (312 patients). The EFS hazard ratio (HR) for achieving MRD negativity is 0.23 (95% Bayesian credible interval [BCI] 0.18-0.28) for pediatric patients and 0.28 (95% BCI, 0.24-0.33) for adults. The respective HRs in OS are 0.28 (95% BCI, 0.19-0.41) and 0.28 (95% BCI, 0.20-0.39). The effect was similar across all subgroups and covariates.

Conclusions and Relevance

The value of having achieved MRD negativity is substantial in both pediatric and adult patients with ALL. These results are consistent across therapies, methods of and times of MRD assessment, cutoff levels, and disease subtypes. Minimal residual disease status warrants consideration as an early measure of disease response for evaluating new therapies, improving the efficiency of clinical trials, accelerating drug development, and for regulatory approval. A caveat is that an accelerated approval of a particular new drug using an intermediate end point, such as MRD, would require confirmation using traditional efficacy end points.

When Less Is Good, Is None Better? The Prognostic and Therapeutic Significance of Peri-Transplant Minimal Residual Disease Assessment in Pediatric Acute Lymphoblastic Leukemia

The measurement of minimal residual disease (MRD) in pediatric acute lymphoblastic leukemia (ALL) has become the most important prognostic tool of, and the backbone to, upfront risk stratification. While MRD assessment is the standard of care for assessing response and predicting outcomes for pediatric patients with ALL receiving chemotherapy, its use in allogeneic hematopoietic stem cell transplant (HSCT) has been less clearly defined. Herein, we discuss the importance of MRD assessment during the peri-HSCT period and its role in prognostication and management.

Synergistic antileukemic therapies in NOTCH1-induced T-ALL

The Notch1 gene is a major oncogenic driver and therapeutic target in T-cell acute lymphoblastic leukemia (T-ALL). However, inhibition of NOTCH signaling with γ-secretase inhibitors (GSIs) has shown limited antileukemic activity in clinical trials. Here we performed an expression-based virtual screening to identify highly active antileukemic drugs that synergize with NOTCH1 inhibition in T-ALL. Among these, withaferin A demonstrated the strongest cytotoxic and GSI-synergistic antileukemic effects in vitro and in vivo. Mechanistically, network perturbation analyses showed eIF2A-phosphorylation-mediated inhibition of protein translation as a critical mediator of the antileukemic effects of withaferin A and its interaction with NOTCH1 inhibition. Overall, these results support a role for anti-NOTCH1 therapies and protein translation inhibitor combinations in the treatment of T-ALL.

Tumor suppressors BTG1 and IKZF1 cooperate during mouse leukemia development and increase relapse risk in B-cell precursor acute lymphoblastic leukemia patients

Deletions and mutations affecting lymphoid transcription factor IKZF1 (IKAROS) are associated with an increased relapse risk and poor outcome in B-cell precursor acute lymphoblastic leukemia. However, additional genetic events may either enhance or negate the effects of IKZF1 deletions on prognosis. In a large discovery cohort of 533 childhood B-cell precursor acute lymphoblastic leukemia patients, we observed that single-copy losses of BTG1 were significantly enriched in IKZF1-deleted B-cell precursor acute lymphoblastic leukemia (P=0.007). While BTG1 deletions alone had no impact on prognosis, the combined presence of BTG1 and IKZF1 deletions was associated with a significantly lower 5-year event-free survival (P=0.0003) and a higher 5-year cumulative incidence of relapse (P=0.005), when compared with IKZF1-deleted cases without BTG1 aberrations. In contrast, other copy number losses commonly observed in B-cell precursor acute lymphoblastic leukemia, such as CDKN2A/B, PAX5, EBF1 or RB1, did not affect the outcome of IKZF1-deleted acute lymphoblastic leukemia patients. To establish whether the combined loss of IKZF1 and BTG1 function cooperate in leukemogenesis, Btg1-deficient mice were crossed onto an Ikzf1 heterozygous background. We observed that loss of Btg1 increased the tumor incidence of Ikzf1^+/− mice in a dose-dependent manner. Moreover, murine B cells deficient for Btg1 and Ikzf1^+/− displayed increased resistance to glucocorticoids, but not to other chemotherapeutic drugs. Together, our results identify BTG1 as a tumor suppressor in leukemia that, when deleted, strongly enhances the risk of relapse in IKZF1-deleted B-cell precursor acute lymphoblastic leukemia, and augments the glucocorticoid resistance phenotype mediated by the loss of IKZF1 function.