Concordance of peripheral blood and bone marrow measurable residual disease in adult acute lymphoblastic leukemia

How I use next-generation sequencing-MRD to plan approach and prevent relapse after HCT for children and adults with ALL

ABSTRACT

Measurable residual disease (MRD) evaluation by multiparameter flow cytometry (MFC) or quantitative polymerase chain reaction methods is an established standard of care for assessing risk of relapse before or after hematopoietic cell transplantation (HCT) for acute lymphoblastic leukemia (ALL). Next-generation sequencing (NGS)-MRD has emerged as a highly effective approach that allows for the detection of lymphoblasts at a level of <1 in 106 nucleated cells, increasing sensitivity of ALL detection by 2 to 3 logs. Early studies have shown superior results compared with MFC and suggest that NGS-MRD may allow for the determination of patients in whom reduced toxicity transplant preparative approaches could be deployed without sacrificing outcomes. Many centers/study groups have implemented immune modulation approaches based on MRD measurements that have resulted in improved outcomes. Challenges remain with NGS-MRD, because it is not commercially available in many countries, and interpretation of results can be complex. Through patient case review, discussion of relevant studies, and detailed expert opinion, we share our approach to NGS-MRD testing before and after HCT in pediatric and adult ALL. Improved pre-HCT risk classification and post-HCT monitoring for relapse in bone marrow and less invasive peripheral blood monitoring by NGS-MRD may lead to alternative approaches to prevent relapse in patients undergoing this challenging procedure.

Laboratory validation and clinical utility of next-generation sequencing-based IGH/TCR clonality testing for the monitoring of measurable residual disease in acute lymphoblastic leukaemia: real-world experience at Austin Pathology

Measurable residual disease (MRD) testing is an essential aspect of disease prognostication in acute lymphoblastic leukaemia (ALL) and informs clinical decisions. The depth of MRD clearance is highly relevant and requires assays with sufficient sensitivity. Austin Pathology is one of the few laboratories in Australia currently utilising a fully validated and National Association of Testing Authorities (NATA)-accredited ultrasensitive next-generation sequencing (NGS) platform for MRD monitoring in ALL. This technology is based on the detection of clonal rearrangement of immunoglobulin and T cell receptor genes in leukaemic cells, and is capable of achieving a limit of detection at least one to two logs below that of multiparametric flow cytometry (MFC). In this retrospective analysis, we report a clonotype detection rate of up to 85.7% at diagnosis, and a concordance rate of 78.7% in MRD results between NGS and MFC. Of the discordant samples, nearly all were NGS+/MFC-, highlighting the superior sensitivity of NGS. The enhanced sensitivity is clinically relevant, as discordant MRD results often heralded fulminant relapse, and therefore offer clinicians additional lead time and a window of opportunity to initiate pre-emptive therapy. Notwithstanding a small and heterogeneous cohort, our real-world survival data indicate an intermediate relapse risk for NGS+/MFC- patients. In light of recent approval of Medicare rebatable ALL MRD testing, we discuss how NGS can complement other techniques such as MFC in personalising management strategies. We recommend routine clonality testing by NGS at diagnosis and use a multi-modality approach for subsequent MRD monitoring.

Advances in the treatment of Philadelphia chromosome negative acute lymphoblastic leukemia

There have been major paradigm shifts in the treatment of Philadelphia chromosome negative (Ph-) acute lymphoblastic leukemia (ALL) in the last decade with the introduction of new immunotherapies and targeted agents, adoption of pediatric-type chemotherapy protocols in younger adults as well as chemotherapy light approaches in older adults and the incorporation of measurable residual disease (MRD) testing to inform clinical decision making. With this, treatment outcomes in adult Ph- ALL have improved across all age groups. However, a subset of patients will still develop relapsed disease, which can be challenging to treat and associated with poor outcomes. Here we review the treatment of Ph- ALL in both younger and older adults, including the latest advancements and future directions.

Persistent or New Cytopenias Predict Relapse Better than Routine Bone Marrow Aspirate Evaluations After Hematopoietic Cell Transplantation for Acute Leukemia or Myelodysplastic Syndrome in Children and Young Adult Patients

The clinical value of serial routine bone marrow aspirates (rBMAs) in the first year after allogeneic hematopoietic cell transplantation (alloHCT) to detect or predict relapse of acute leukemia (AL) and myelodysplastic syndrome (MDS) in pediatric and young adult patients is unclear. The purpose of this analysis was to determine if assessment of minimal residual disease (MRD) by multiparameter flow cytometry (MFC, MFC-MRD) or donor chimerism (DC) in rBMAs or serial complete blood counts (CBCs) done in the year after alloHCT predicted relapse of AL or MDS in pediatric and young adult patients. We completed a retrospective analysis of patients with AL or MDS who had rBMAs performed after alloHCT between January 2012 and June 2018. Bone marrow (BM) was evaluated at approximately 3, 6, and 12 months for disease recurrence by morphology, MFC-MRD, and percent DC by short tandem repeat molecular testing. CBCs were performed at every clinic visit. The main outcome of interest was an assessment of whether MFC-MRD or DC in rBMAs or serial CBCs done in the year after alloHCT predicted relapse in AL or MDS pediatric and young adult patients. A total of 121 recipients with a median age of 13 years (range 1 to 32) were included: 108 with AL and, 13 with MDS. A total of 423 rBMAs (median 3; 0 to 13) were performed. Relapse at 2 years was 23% (95% CI: 16% to 31%) and at 5 years 25% (95% CI: 18% to 33%). One hundred fifty-four of 157 (98%) rBMAs evaluated for MRD by MFC were negative and did not preclude subsequent relapse. Additionally, low DC (<95%) did not predict relapse and high DC (≥95%) did not preclude relapse. For patients alive without relapse at 1 year, BM DC (P = .74) and peripheral T-cell DC (P = .93) did not predict relapse. Six patients with low-level T-cell and/or BM DC had a total of 8 to 20 BM evaluations, none of these patients relapsed. However, CBC results were informative for relapse; 28 of 31 (90%) relapse patients presented with an abnormal CBC with peripheral blood (PB) blasts (16 patients), cytopenias (9 patients), or extramedullary disease (EMD, 3 patients). Two patients with BM blasts >5% on rBMA had circulating blasts within 5 weeks of rBMA. Neutropenia (ANC <1.5 K/mcl) at 1 year was predictive of relapse (P = .01). Neutropenia and thrombocytopenia (<160 K/mcl) were predictive of disease-free survival (DFS) with inferior DFS for ANC <1.5 K/mcl, P = .001, or platelet count <160 K/mcl (P = .04). These results demonstrate rBMAs after alloHCT assessed for MRD by MFC and/or for level of DC are poor predictors for relapse in pediatric and young adult patients with AL or MDS. Relapse in these patients presents with PB blasts, cytopenias, or EMD. ANC and platelet count at 1-year were highly predictive for DFS.

MRD in Philadelphia Chromosome-Positive ALL: Methodologies and Clinical Implications

PURPOSE OF REVIEW

Measurable residual disease (MRD) is integral in the management of Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). This review discusses the current methods used to evaluate MRD as well as the interpretation, significance, and incorporation of MRD in current practice.

RECENT FINDINGS

New molecular technologies have allowed the detection of MRD to levels as low as 10- 6. The most used techniques to evaluate MRD are multiparametric flow cytometry (MFC), quantitative reverse transcription polymerase chain reaction (RT-qPCR), and high-throughput next-generation sequencing (NGS). Each method varies in terms of advantages, disadvantages, and MRD sensitivity. MRD negativity after induction treatment and after allogeneic hematopoietic cell transplantation (HCT) is an important prognostic marker that has consistently been shown to be associated with improved outcomes. Blinatumomab, a new targeted therapy for Ph + ALL, demonstrates high efficacy in eradicating MRD and improving patient outcomes. In the relapsed/refractory setting, the use of inotuzumab ozogamicin and tisagenlecleucel has shown promise in eradicating MRD. The presence of MRD has become an important predictive measure in Ph + ALL. Current studies evaluate the use of MRD in treatment decisions, especially in expanding therapeutic options for Ph + ALL, including tyrosine kinase inhibitors, targeted antibody therapies, chimeric antigen receptor cell therapy, and HCT.

Concordance of Next-Generation Sequencing and Multiparametric Flow Cytometry Methods for Detecting Measurable Residual Disease in Adult Acute Lymphoblastic Leukemia: Optimizing Prediction of Clinical Outcomes From a Single-Center Study

INTRODUCTION

Detection of measurable residual disease (MRD) in adults with acute lymphoblastic leukemia (ALL) is a vital biomarker in risk prediction and treatment selection. Next-generation sequencing (NGS) offers greater sensitivity relative to multiparametric flow cytometry (MFC) and may be a better predictive tool for identifying ALL patients at risk of relapse.

PATIENTS AND METHODS

This single-center retrospective study compares MRD detection by NGS versus MFC in 52 adult B- and T-ALL patients treated at our institution between 2018 and 2023. Pretreatment bone marrow samples were used for assay calibration, while post-treatment MRD assessment was completed up to 4.5 months after the first complete remission (CR1) using an MRD cutoff of 10-6 for distinguishing relapse risk.

RESULTS

The 2-year cumulative incidence of relapse (CIR) among patients who were MRD positive using MFC and NGS was 39.5% and 46.2%, respectively. Unlike MFC, post-CR1 MRD positivity with NGS significantly predicted CIR (HR = 9.47, P = .028). In patients who were MRD negative by MFC, low levels of MRD detected by NGS distinguished patients at high risk of relapse (HR 10.3, P = .026, 2-year CIR 51.6%).

CONCLUSION

Our data suggests that assessment of post-CR1 MRD using a highly sensitive NGS assay can identify ALL patients undergoing frontline therapy at increased risk of relapse and guide the use of adjuvant therapy.

Quantification of Measurable Residual Disease Detection by Next-Generation Sequencing-Based Clonality Testing in B-Cell and Plasma Cell Neoplasms

Next-generation sequencing (NGS)-based measurable residual disease (MRD) monitoring in post-treatment settings can be crucial for relapse risk stratification in patients with B-cell and plasma cell neoplasms. Prior studies have focused on validation of various technical aspects of the MRD assays, but more studies are warranted to establish the performance characteristics and enable standardization and broad utilization in routine clinical practice. Here, the authors describe an NGS-based IGH MRD quantification assay, incorporating a spike-in calibrator for monitoring B-cell and plasma cell neoplasms based on their unique IGH rearrangement status. Comparison of MRD status (positive or undetectable) by NGS and flow cytometry (FC) assays showed high concordance (91%, 471/519 cases) and overall good linear correlation in MRD quantitation, particularly for chronic lymphocytic leukemia and B-lymphoblastic leukemia/lymphoma (R = 0.85). Quantitative correlation was lower for plasma cell neoplasms, where underestimation by FC is a known limitation. No significant effects on sequencing efficiency by the spike-in calibrator were observed, with excellent inter- and intra-assay reproducibility within the authors' laboratory, and in comparison to an external laboratory, using the same assay and protocols. Assays performed both at internal and external laboratories showed highly concordant MRD detection (100%) and quantitation (R = 0.97). Overall, this NGS-based MRD assay showed highly reproducible results with quantitation that correlated well with FC MRD assessment, particularly for B-cell neoplasms.

Development and evaluation of a rapid one-step high sensitivity real-time quantitative PCR system for minor BCR-ABL (e1a2) test in Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL)

OBJECTIVE

Minimal residual disease assessment of BCR-ABL messenger ribonucleic acid levels is crucial in Philadelphia chromosome-positive acute lymphoblastic leukemia for prognosis and treatment planning. However, accurately quantifying minor BCR-ABL transcripts, which comprise 70% of Philadelphia chromosome-positive acute lymphoblastic leukemia cases, lacks a national-approved method.

METHODS

We developed the "Otsuka" minor BCR-ABLmessenger ribonucleic acid assay kit with exceptional precision (0.00151%). Minor BCR-ABL messenger ribonucleic acid levels were analyzed in 175 adults, 36 children with acute lymphoblastic leukemia and 25 healthy individuals to evaluate the kit's performance.

RESULTS

The "Otsuka" kit showed high concordance with a commonly used chimeric gene screening method, indicating reliable detection of positive cases. Quantitative results demonstrated a robust correlation with both a laboratory-developed test and a diagnostic research product. The "Otsuka" kit performs comparably or even surpass to conventional products, providing valuable insights into Philadelphia chromosome-positive acute lymphoblastic leukemia pathology.

CONCLUSIONS

The 'Otsuka" minor BCR-ABL messenger ribonucleic acid assay kit exhibits excellent performance in quantifying minor BCR-ABL transcripts in Philadelphia chromosome-positive acute lymphoblastic leukemia patients. Our results align well with established screening methods and show a strong correlation with laboratory-developed tests and diagnostic research products. The "Otsuka" kit holds great promise as a valuable tool for understanding Philadelphia chromosome-positive acute lymphoblastic leukemia pathology and guiding effective treatment strategies.

Measurable residual disease study through three different methods can anticipate relapse and guide early interventions in childhood acute lymphoblastic leukemia

INTRODUCTION

Acute lymphoblastic leukemia (ALL) is the most common cancer among children. Measurable residual disease (MRD, previously named minimal residual disease) study can guide therapy adjustments or preemptive interventions that might avoid hematological relapse.

METHODS

Clinical decision making and patient outcome were evaluated in 80 real-life childhood ALL patients, according to the results observed in 544 bone marrow samples analyzed with three MRD methods: multiparametric flow cytometry (MFC), fluorescent in-situ hybridization (FISH) on B or T-purified lymphocytes and patient-specific nested reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Estimated 5 year overall survival and event-free survival were 94% and 84.1%, respectively. A total of 12 relapses in 7 patients were associated with positive MRD detection with at least one of the three methods: MFC (p < 0.00001), FISH (p < 0.00001) and RT-PCR (p = 0.013). MRD assessment allowed the anticipation of relapse and adapted early interventions with different approaches including chemotherapy intensification, blinatumomab, HSCT and targeted therapy to halt relapse in five patients, although two of them relapsed afterwards.

CONCLUSION

MFC, FISH and RT-PCR are complementary methods for MRD monitoring in pediatric ALL. Although, our data clearly show that MDR positive detection is associated with relapse, continuation of standard treatment, intensification or other early interventions were able to halt relapse in patients with different risks and genetic background. More sensitive and specific methods are warranted to enhance this approach. However, whether early treatment of MRD can improve overall survival in patients with childhood ALL needs to be evaluated in adequately controlled clinical trials.

Private Payer and Medicare Coverage Policies for Use of Circulating Tumor DNA Tests in Cancer Diagnostics and Treatment

BACKGROUND

Circulating tumor DNA (ctDNA) is used to select initial targeted therapy, identify mechanisms of therapeutic resistance, and measure minimal residual disease (MRD) after treatment. Our objective was to review private and Medicare coverage policies for ctDNA testing.

METHODS

Policy Reporter was used to identify coverage policies (as of February 2022) from private payers and Medicare Local Coverage Determinations (LCDs) for ctDNA tests. We abstracted data regarding policy existence, ctDNA test coverage, cancer types covered, and clinical indications. Descriptive analyses were performed by payer, clinical indication, and cancer type.

RESULTS

A total of 71 of 1,066 total policies met study inclusion criteria, of which 57 were private policies and 14 were Medicare LCDs; 70% of private policies and 100% of Medicare LCDs covered at least one indication. Among 57 private policies, 89% specified a policy for at least 1 clinical indication, with coverage for ctDNA for initial treatment selection most common (69%). Of 40 policies addressing progression, coverage was provided 28% of the time, and of 20 policies addressing MRD, coverage was provided 65% of the time. Non-small cell lung cancer (NSCLC) was the cancer type most frequently covered for initial treatment (47%) and progression (60%). Among policies with ctDNA coverage, coverage was restricted to patients without available tissue or in whom biopsy was contraindicated in 91% of policies. MRD was commonly covered for hematologic malignancies (30%) and NSCLC (25%). Of the 14 Medicare LCD policies, 64% provided coverage for initial treatment selection and progression, and 36% for MRD.

CONCLUSIONS

Some private payers and Medicare LCDs provide coverage for ctDNA testing. Private payers frequently cover testing for initial treatment, especially for NSCLC, when tissue is insufficient or biopsy is contraindicated. Coverage remains variable across payers, clinical indications, and cancer types despite inclusion in clinical guidelines, which could impact delivery of effective cancer care.

Using Measurable Residual Disease to Optimize Management of AML, ALL, and Chronic Myeloid Leukemia

In this review, we discuss the use of measurable residual disease (MRD) in AML, ALL, and chronic myeloid leukemia (CML). Our aims were to review the different methodologies for MRD assessment; describe the clinical relevance and medical decision making on the basis of MRD; compare and contrast the usage of MRD across AML, ALL, and CML; and discuss what patients need to know about MRD as it relates to their disease status and treatment. Finally, we discuss ongoing challenges and future directions with the goal of optimizing MRD usage in leukemia management.

Myeloid NGS Analyses of Paired Samples from Bone Marrow and Peripheral Blood Yield Concordant Results: A Prospective Cohort Analysis of the AGMT Study Group

Background: Next generation sequencing (NGS) has become indispensable for diagnosis, risk stratification, prognostication, and monitoring of response in patients with myeloid neoplasias. Guidelines require bone marrow evaluations for the above, which are often not performed outside of clinical trials, indicating a need for surrogate samples. Methods: Myeloid NGS analyses (40 genes and 29 fusion drivers) of 240 consecutive, non-selected, prospectively collected, paired bone marrow/peripheral blood samples were compared. Findings: Very strong correlation (r = 0.91, p < 0.0001), high concordance (99.6%), sensitivity (98.8%), specificity (99.9%), positive predictive value (99.8%), and negative predictive value (99.6%) between NGS analyses of paired samples was observed. A total of 9/1321 (0.68%) detected mutations were discordant, 8 of which had a variant allele frequency (VAF) ≤ 3.7%. VAFs between peripheral blood and bone marrow samples were very strongly correlated in the total cohort (r = 0.93, p = 0.0001) and in subgroups without circulating blasts (r = 0.92, p < 0.0001) or with neutropenia (r = 0.88, p < 0.0001). There was a weak correlation between the VAF of a detected mutation and the blast count in either the peripheral blood (r = 0.19) or the bone marrow (r = 0.11). Interpretation: Peripheral blood samples can be used to molecularly classify and monitor myeloid neoplasms via NGS without loss of sensitivity/specificity, even in the absence of circulating blasts or in neutropenic patients.

Targeted therapy using larotrectinib and venetoclax for the relapsed/refractory T-cell acute lymphoblastic leukemia harboring a cryptic ETV6-NTRK3 fusion

Outcomes for patients with relapsed and refractory (R/R) T-cell acute lymphoblastic leukemia (T-ALL) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) are dismal, with few available treatments. Recently, identification of cancer patients harboring neurotrophic tropomyosin receptor kinase (NTRK) gene fusions is constantly increasing, especially with the advent of NTRK inhibitors. However, the role of ETV6-NTRK3 in T-ALL has not been investigated. This case represented the first detailed report of T-ALL patient harboring a cryptic ETV6-NTRK3 fusion with an unfavorable prognosis, not only because of leukemia resistant to the standard multiagent chemotherapy but also early relapse after allo-HSCT. Acquired EP300 mutation was found at relapse, which could explain the cause of recurrence and affect the follow-up treatment. Combined targeted therapy like larotrectinib allied with pan-targeted BCL-2 inhibitor venetoclax, may be a potential maintenance treatment in R/R ETV6-NTRK3 positive leukemia after allo-HSCT. The leukemic clonal evolution might be revealed through transcriptome sequencing and overcome by drugs with universal targets. Our case demonstrated that both comprehensive profiling techniques (such as transcriptome sequencing, multiparameter flow cytometry, and digital droplet polymerase chain reaction) and a multimodality treatment strategy were critical for anticipating an early relapse and personalized therapy of R/R T-cell leukemia.

Efficacy and safety of chimeric antigen receptor T-cell (CAR-T) therapy in hematologic malignancies: a living systematic review on comparative studies

Background

Chimeric antigen receptor T-cell (CAR-T) cell therapies have been claimed to be curative in responsive patients. Nonetheless, response rates can vary according to different characteristics, and these therapies are associated with important adverse events such as cytokine release syndrome, neurologic adverse events, and B-cell aplasia.

Objectives

This living systematic review aims to provide a timely, rigorous, and continuously updated synthesis of the evidence available on the role of CAR-T therapy for the treatment of patients with hematologic malignancies.

Design

A systematic review with meta-analysis of randomized controlled trials (RCTs) and comparative non-randomized studies of interventions (NRSI), evaluating the effect of CAR-T therapy versus other active treatments, hematopoietic stem cell transplantation, standard of care (SoC) or any other intervention, was performed in patients with hematologic malignancies. The primary outcome is overall survival (OS). Certainty of the evidence was determined using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.

Data sources and Methods

Searches were performed in the Epistemonikos database, which collates information from multiple sources to identify systematic reviews and their included primary studies, including Cochrane Database of Systematic Reviews, MEDLINE, EMBASE, CINAHL, PsycINFO, LILACS, DARE, HTA Database, Campbell database, JBI Database of Systematic Reviews and Implementation Reports, EPPI-Centre Evidence Library. A manual search was also carried out. We included the evidence published up to 1 July 2022.

Results

We included the evidence published up to 1 July 2022. We considered 139 RCTs and 1725 NRSI as potentially eligible. Two RCTs (N = 681) comparing CAR-T therapy with SoC in patients with recurrent/relapsed (R/R) B-cell lymphoma were included. RCTs did not show statistical differences in OS, serious adverse events, or total adverse events with grade ⩾ 3. Higher complete response with substantial heterogeneity [risk ratio = 1.59; 95% confidence interval (CI) = (1.30-1.93); I ² = 89%; 2 studies; 681 participants; very low certainty evidence] and higher progression-free survival [hazard ratio for progression or death = 0.49; 95% CI = (0.37-0.65); 1 study; 359 participants; moderate certainty evidence] were reported with CAR-T therapies. Nine NRSI (N = 540) in patients with T or B-cell acute lymphoblastic leukemia or R/R B-cell lymphoma were also included, providing secondary data. In general, the GRADE certainty of the evidence for main outcomes was mostly low or very low.

Conclusion

So far, assuming important limitations in the level of certainty due to scarce and heterogenous comparative studies, CAR-T therapies have shown some benefit in terms of progression-free survival, but no overall survival, in patients with R/R B-cell lymphoma. Despite one-arm trials have already facilitated approval of CAR-T cell treatments, additional evidence from large comparative studies is still needed to better characterize the benefit-harm ratio of the use of CAR-T in a variety of patient populations with hematological malignancies.

Registration

https://doi.org/10.12688/openreseurope.14390.1.

PROSPERO/OSF Preregistration

10.17605/OSF.IO/V6HDX.

SOHO State of the Art Updates and Next Questions: Measurable Residual Disease in Acute Lymphoblastic Leukemia - Optimization and Innovation in 2022 and Beyond

Measurable residual disease (MRD) is an established component of acute lymphoblastic leukemia (ALL) management in both children and adults. Society guidelines and expert consensus documents include assessment of MRD as the standard of care following induction therapy, consolidation therapy, and at additional time points, depending on the treatment regimen administered. Further, the approval of blinatumomab for MRD+ B-ALL has advanced the concept of MRD response as a clinical endpoint in ALL. Although the utility of MRD in ALL has been well defined over the last decades, several questions remain. In this review we focus on areas of ongoing controversy and exploration in ALL MRD, including the following: (1) Does increasing the depth of MRD assessment add prognostic value? (2) Is there a role for ongoing MRD monitoring once patients achieve MRD response? (3) Can MRD assessment of the peripheral blood be substituted for bone marrow? (4) Should MRD assays be applied to the analysis of the central nervous system (CNS)? Ongoing studies should answer the majority of these questions in the coming years.

Measurable residual disease in acute lymphoblastic leukemia: methods and clinical context in adult patients

Measurable residual disease (MRD) is the most powerful independent predictor of risk of relapse and long-term survival in adults and children with acute lymphoblastic leukemia (ALL). For almost all patients with ALL there is a reliable method to evaluate MRD, which can be done using multi-color flow cytometry, quantitative polymerase chain reaction to detect specific fusion transcripts or immunoglobulin/T-cell receptor gene rearrangements, and high-throughput next-generation sequencing. While next-generation sequencing-based MRD detection has been increasingly utilized in clinical practice due to its high sensitivity, the clinical significance of very low MRD levels (<10-4) is not fully characterized. Several new immunotherapy approaches including blinatumomab, inotuzumab ozogamicin, and chimeric antigen receptor T-cell therapies have demonstrated efficacy in eradicating MRD in patients with B-ALL. However, new approaches to target MRD in patients with T-ALL remain an unmet need. As our MRD detection assays become more sensitive and expanding novel therapeutics enter clinical development, the future of ALL therapy will increasingly utilize MRD as a criterion to either intensify or modify therapy to prevent relapse or de-escalate therapy to reduce treatment-related morbidity and mortality.

SOHO State of the Art Updates and Next Questions: Novel Transplant and Post-Transplant Options in Acute Lymphoblastic Leukemia

Allogeneic hematopoietic cell transplantation (alloHCT) is a potentially curative treatment approach for patients with high-risk acute lymphoblastic leukemia (ALL). Despite development of several novel therapies targeting B-cell ALL, alloHCT continues to play an essential role in management, but the identification of patients who are most likely to benefit from alloHCT in first or subsequent remissions continues to evolve. Broader donor options, including haploidentical donors and umbilical cord blood, have enabled alloHCT for more patients, but improvements in front-line therapy and increasing use of high-sensitivity measurable residual disease (MRD) quantification continue to modify the calculus for selecting which patients require transplantation. MRD quantification has become increasingly important as a prognostic indicator, as well as a trigger for therapeutic intervention, since the achievement of MRD negative complete remission is well-established to be associated with improved transplant outcomes. ALL remains the only malignancy with approved therapy for MRD positivity after achievement of remission, and use of Blinatumomab in this setting currently appears to be most effective when used as a bridge-to-transplant, rather than a destination or purely consolidative therapy. Expanding options for those with relapsed/refractory disease, including chimeric antigen receptor (CAR)-T cells, also render more patient in suitably deep remissions to enable alloHCT with a high likelihood of success. It remains unclear whether CAR-T cell therapies may obviate the need for alloHCT in some patients, and currently available data suggest there remains a role for alloHCT after CAR-T. Together, these therapeutic advances appear to be improving post-transplant outcomes. Nevertheless, more remains to be studied regarding how to optimize use of available and emerging cellular and immune modulating therapies to maximize the likelihood of long-term post-alloHCT remission in high-risk ALL.

MRD in ALL: Optimization and Innovations

PURPOSE OF REVIEW

Measurable residual disease (MRD) is an important monitoring parameter that can help predict survival outcomes in acute lymphoblastic leukemia (ALL). Identifying patients with MRD has the potential to decrease the risk of relapse with the initiation of early salvage therapy and to help guide decision making regarding allogeneic hematopoietic cell transplantation. In this review, we discuss MRD in ALL, focusing on advantages and limitations between MRD testing techniques and how to monitor MRD in specific patient populations.

RECENT FINDINGS

MRD has traditionally been measured through bone marrow samples, but more data for evaluation of MRD via peripheral blood is emerging. Current and developmental testing strategies for MRD include multiparametric flow cytometry (MFC), next-generation sequencing (NGS), quantitative polymerase chain reaction (qPCR), and ClonoSeq. Novel therapies are incorporating MRD as an outcome measure to demonstrate efficacy, including blinatumomab, inotuzumab ozogamicin, and chimeric antigen receptor T (CAR-T) cell therapy. Understanding how to incorporate MRD testing into the management of ALL could improve patient outcomes and predict efficacy of new therapy options.

High-sensitivity next-generation sequencing MRD assessment in ALL identifies patients at very low risk of relapse

Measurable residual disease (MRD) is highly prognostic for relapse and overall survival (OS) in acute lymphoblastic leukemia (ALL), although many patients with apparent "MRD negativity" by standard assays still relapse. We evaluated the clinical impact of a highly sensitive next-generation sequencing (NGS) MRD assay in 74 adults with ALL undergoing frontline therapy. Among remission samples that were MRD negative by multiparameter flow cytometry (MFC), 46% were MRD positive by the NGS assay. After one cycle of induction chemotherapy, MRD negativity by MFC at a sensitivity of 1x10-4 and NGS at a sensitivity of 1x10-6 was achieved in 66% and 23% of patients, respectively. The 5-year cumulative incidence of relapse (CIR) among patients who achieved MRD negativity by MFC at CR was 29%; in contrast, no patients who achieved early MRD negativity by NGS relapsed, and their 5-year OS was 90%. NGS MRD negativity at CR was associated with significantly decreased risk of relapse compared with MRD positivity (5-year CIR: 0% versus 45%, respectively, P=0.04). Among patients who were MRD negative by MFC, detection of low levels of MRD by NGS identified patients who still had a significant risk of relapse (5-year CIR: 39%). Early assessment of MRD using a highly sensitive NGS assay adds clinically relevant prognostic information to standard MFC-based approaches and can identify patients with ALL undergoing frontline therapy who have a very low risk of relapse and excellent long-term survival.

Allogeneic Hematopoietic Cell Transplantation for Adult Acute Lymphoblastic Leukemia in the Modern Era

Allogeneic hematopoietic cell transplantation (HCT) remains an important treatment for adults with acute lymphoblastic leukemia (ALL). We hypothesized that advances in ALL and transplantation have resulted in improved HCT outcomes in recent years. In this study, we evaluated the characteristics and outcomes of adult ALL patients undergoing allogeneic HCT over the last decade. Patients with ALL aged 18 years and older who underwent allogeneic HCT at Stanford University between 2008 and 2019 were included in this study. Patients were divided into 2 eras based on year of HCT: 2008 to 2013 (earlier era) and 2014 to 2019 (later era). A total of 285 patients were included: 119 patients underwent HCT in the earlier era and 166 in the later era. Patients who underwent transplantation in the later era were more likely to be Hispanic (38% versus 21%) and to have an HCT-comorbidity index ≥3 (31% versus 18%). Donor source for HCT also differed with an increase in the use of HLA-mismatched donor sources (38% versus 24%), notably umbilical cord blood in the later era (16% versus 0%). Patients in the later era were less likely to undergo transplantation with active disease (4% versus 16%); pre-HCT rates of measurable residual disease were similar across the eras (38% versus 40%). In unadjusted analyses, overall survival (OS) improved across eras, with 2-year estimates for the later and earlier eras of 73% (95% confidence interval [CI], 66%-80%) versus 55% (95% CI, 46%-64%), respectively. Multivariable analysis confirmed the association between later era and OS (hazard ratio = 0.52, 95% CI, 0.34-0.78). Finally, among patients relapsing after HCT (25% in later era and 33% in earlier era), the use of novel immunotherapies increased in the later era (44% versus 3%), as did the median OS after post-HCT relapse (16 months versus 8 months, P< .001). OS after HCT for adult ALL has improved in recent years. This is due, in part, to a significant improvement in the ability to effectively salvage adults with ALL relapsing after HCT.

Innovative Approaches to the Management of Acute Lymphoblastic Leukemia Across the Age Spectrum

Adults compose nearly half of all patients diagnosed with acute lymphoblastic leukemia (ALL) and historically have had poor survival compared with pediatric patients. Recently approved therapies, such as monoclonal antibodies, CAR T-cell constructs, and next-generation tyrosine kinase inhibitors, have improved survival in relapsed and refractory ALL, and studies are now examining incorporating these treatments and others into the upfront setting. In adolescent and young adult patients, use of pediatric-based regimens has already improved survival compared with historical controls, and the addition of monoclonal antibodies, such as inotuzumab ozogamicin and blinatumomab, may further enhance this survival benefit. In older adults, approaches have centered on minimizing conventional chemotherapy to decrease toxicity by incorporating monoclonal antibodies and other novel therapies to increase efficacy. With the addition of tyrosine kinase inhibitors to chemotherapy for patients with Philadelphia chromosome-positive ALL, survival of this once poor-prognosis ALL subtype now approaches or exceeds outcomes of other subtypes of adult ALL. Further refinements in the backbone treatment regimen and optimal consolidation approaches will likely improve survival further. Although allogeneic hematopoietic stem cell transplant was previously routinely used as consolidation for adults with ALL, incorporation of measurable residual disease and other risk stratification strategies has enabled better identification of patients who will benefit from allogeneic hematopoietic stem cell transplant. Ongoing clinical trials investigating these approaches will continue the evolution of treatment approaches for adults with ALL, with further improvement in outcomes anticipated.

The Minimal Residual Disease Using Liquid Biopsies in Hematological Malignancies

Simple Summary

Monitoring the response to treatment in hematologic malignancies is essential in defining the best way to optimize patient management. In general, achieving a deeper response has been shown to lead to a better prognosis, and the techniques used to study the minimal residual disease (MRD) are becoming more precise. The use of liquid biopsies, that is, analyzing the presence of alterations in nucleic acids, usually in peripheral blood or other biological fluids, is being studied and optimized with increasingly innovative molecular techniques, such as next-generation sequencing (NGS) in the monitoring of the MRD, avoiding, in many cases, more invasive tests in different hematological neoplasms. Currently, liquid biopsies are not standardized for the MRD monitoring, but there is increasing evidence of its correlation with other techniques to measure responses to treatments and patient outcomes.

Abstract

The study of cell-free DNA (cfDNA) and other peripheral blood components (known as “liquid biopsies”) is promising, and has been investigated especially in solid tumors. Nevertheless, it is increasingly showing a greater utility in the diagnosis, prognosis, and response to treatment of hematological malignancies; in the future, it could prevent invasive techniques, such as bone marrow (BM) biopsies. Most of the studies about this topic have focused on B-cell lymphoid malignancies; some of them have shown that cfDNA can be used as a novel way for the diagnosis and minimal residual monitoring of B-cell lymphomas, using techniques such as next-generation sequencing (NGS). In myelodysplastic syndromes, multiple myeloma, or chronic lymphocytic leukemia, liquid biopsies may allow for an interesting genomic representation of the tumor clones affecting different lesions (spatial heterogeneity). In acute leukemias, it can be helpful in the monitoring of the early treatment response and the prediction of treatment failure. In chronic lymphocytic leukemia, the evaluation of cfDNA permits the definition of clonal evolution and drug resistance in real time. However, there are limitations, such as the difficulty in obtaining sufficient circulating tumor DNA for achieving a high sensitivity to assess the minimal residual disease, or the lack of standardization of the method, and clinical studies, to confirm its prognostic impact. This review focuses on the clinical applications of cfDNA on the minimal residual disease in hematological malignancies.

Pharmacotherapeutic management of T-cell acute lymphoblastic leukemia in adults: an update of the literature

INTRODUCTION

T-cell acute lymphoblastic leukemia (T-ALL) is a rare but potentially life-threatening heterogeneous hematologic malignancy that requires prompt diagnosis and treatment by hematologists. So far, therapeutic advances have been achieved in the management of this disease mainly by adopting pediatric-like regimens, and cure rates are significantly worse than in childhood. In T-ALL, less than 70% of adults achieve long-term survival. The prognosis after relapse is still very poor. Hence, there is urgent need to improve therapy of T-ALL by testing new compounds and combinations for the treatment of this disease.

AREAS COVERED

This review provides a comprehensive update on the most recent treatment approaches in adults with de novo and relapsed/refractory adult T-ALL.

EXPERT OPINION

Intensifying chemotherapy may reduce the incidence of recurrent disease in adult patients, but it has not come without a cost. Novel agents with selective T-ALL activity (e.g. nelarabine) may improve survival in some patient subsets. Due to modern genomic and transcriptomic techniques, various novel potential targets might change the treatment landscape in the next few years and will, hopefully alongside with cellular therapies, augment the therapeutic armamentarium in the near future.