Minimal Residual Disease Detection in Acute Lymphoblastic Leukemia

SWIGH-SCORE: A translational light-weight approach in computational detection of rearranged immunoglobulin heavy chain to be used in monoclonal lymphoproliferative disorders

We present a lightweight tool for clonotyping and measurable residual disease (MRD) assessment in monoclonal lymphoproliferative disorders. It is a translational method that enables computational detection of rearranged immunoglobulin heavy chain gene sequences.•The swigh-score clonotyping tool emphasizes parallelization and applicability across sequencing platforms.•The algorithm is based on an adaptation of the Smith-Waterman algorithm for local alignment of reads generated by 2nd and 3rd generation of sequencers.For method validation, we demonstrate the targeted sequences of immunoglobulin heavy chain genes from diagnostic bone marrow using serial dilutions of CD138+ plasma cells from a patient with multiple myeloma. Sequencing libraries from diagnostic samples were prepared for the three sequencing platforms, Ion S5 (Thermo Fisher Scientific), MiSeq (Illumina), and MinION (Oxford Nanopore), using the LymphoTrack assay. Basic quality filtering was performed, and a Smith-Waterman-based swigh-score algorithm was developed in shell and C for clonotyping and MRD assessment using FASTQ data files. Performance is demonstrated across the three different sequencing platforms.

Fmoc-FF hydrogels and nanogels for improved and selective delivery of dexamethasone in leukemic cells and diagnostic applications

Dexamethasone (DEX) is a synthetic analogue of cortisol commonly used for the treatment of different pathological conditions, comprising cancer, ocular disorders, and COVID-19 infection. Its clinical use is hampered by the low solubility and severe side effects due to its systemic administration. The capability of peptide-based nanosystems, like hydrogels (HGs) and nanogels (NGs), to serve as vehicles for the passive targeting of active pharmaceutical ingredients and the selective internalization into leukemic cells has here been demonstrated. Peptide based HGs loaded with DEX were formulated via the "solvent-switch" method, using Fmoc-FF homopeptide as building block. Due to the tight interaction of the drug with the peptidic matrix, a significant stiffening of the gel (G' = 67.9 kPa) was observed. The corresponding injectable NGs, obtained from the sub-micronization of the HG, in the presence of two stabilizing agents (SPAN®60 and TWEEN®60, 48/52 w/w), were found to be stable up to 90 days, with a mean diameter of 105 nm. NGs do not exhibit hemolytic effects on human serum, moreover they are selectively internalized by RS4;11 leukemic cells over healthy PBMCs, paving the way for the generation of new diagnostic strategies targeting onco-hematological diseases.

Can novel methods replace the gold standard chimerism method after allogeneic hematopoietic stem cell transplantation?

After hematopoietic stem cell transplantation, chimerism assay is a useful approach to monitor the success of the transplant and to select the appropriate treatment strategy, such as donor leukocyte infusion or immunosuppressive drug dosage. Short tandem repeat PCR is the method that has been accepted as the gold standard for chimerism. However, it has not yet been sufficient to detect mixed chimerism in patients with minimal residual disease. Simultaneously, recent years have been marked by developing sensitive, high-throughput, and accurate molecular genetic assays. These novel methods have subsequently been adapted for the analysis of post-transplant chimerism. In this review, we discuss the technical features of both novel and conventional gold standard chimerism assays. We also discuss their advantages and disadvantages.

Biomarkers of minimal residual disease and treatment

Minimal residual disease (MRD) has been defined as a very small numbers of cancer cells that remain in the body after curative treatment. Its presence or absence will ultimately determine prognosis. With the introduction of new technologies the presence of MRD in patients with solid tumours can be detected and characterized. As MRD predicts future relapse, be it early or late treatment failure, in an otherwise asymptomatic patient its treatment and when to start treatment remains to be determined. Thus the concepts of personalized medicine using different biomarkers to classify the biological properties of MRD maybe come possible. Based on this determinations it may be possible to use targeted therapies rather than all patients with the same type of cancer receiving a standard treatment. However, it is important to understand the limitations of the different technologies, what these techniques are detecting and how they may help in the treatment of patients with cancer. The majority of published studies are in patients with metastatic cancer and there are few reports in patients with MRD. In this chapter the concept of MRD, the methods used to detect it and what treatments may be effective based on the biological characteristics of the tumour cells as determined by different biomarkers is reviewed. MRD depends on the phenotypic properties of the tumour cells to survive in their new environment and the anti-tumour immune response. This is a dynamic process and changes with time in the wake of immunosuppression caused by the tumour cells and/or the effects of treatment to select resistant tumour cells. With the use of biomarkers to typify the characteristics of MRD and the development of new drugs a personalized treatment can be designed rather than all patients given the same treatment. Patients who are initially negative for MRD may not require further treatment with liquid biopsies used to monitor the patients during follow-up in order to detect those patients who may become MRD positive. The liquid biopsy used during the follow up of MRD positive patients can be used to detect changes in the biological properties of the tumour cells and thus may need treatment changes to overcome tumour cell resistance.

Plasma-derived exosomal miR-326, a prognostic biomarker and novel candidate for treatment of drug resistant pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a cancer with high incidence rate in pediatrics and drug resistance is a major clinical concern for ALL treatment. The current study was designed to evaluate the role of exosomal miR-326 in diagnosis and treatment of children with B-ALL. Exosomes were isolated from plasma samples of 30 patients and B-ALL cell lines followed by characterization, using nanoparticle tracking analysis, immunoblotting assay and electron microscopy. qPCR showed significantly increased levels of miR-326 in patients exosomes compared with non-cancer controls (P < 0.05, AUC = 0.7500). Moreover, a comparison between the sensitive and drug resistant patients revealed a prognostic value for the exosomal miR326 (P < 0.05, AUC = 0.7755). Co-culture studies on drug resistant patient primary cells and B-ALL cell lines suggested that exosomes with high miR-326 level act as vehicles for reducing cells viability. B-ALL cell line transfection with naked miR-326 mimic confirmed the results, and fluorescence microscopy validated uptake and internalization of exosomes by target cells. The novel introduced features of the exosomal miR-326 address a non-invasive way of diagnosing primary drug resistance in pediatric ALL and advocates a novel therapeutic strategy for this cancer.

Applications of Digital Polymerase Chain Reaction (dPCR) in Molecular and Clinical Testing

BACKGROUND

Digital polymerase chain reaction (dPCR) is an accurate and sensitive molecular method that can be used in clinical diagnostic, prognostic, and predictive tests. The key component of the dPCR method is the partitioning of a single reaction into many thousands of droplets, nanochannels or other nano- or picoliter-sized reactions. This results in high enough sensitivity to detect rare nucleic acid targets and provides an absolute quantification of target sequences or alleles compared to other PCR-based methods.

CONTENT

An increasing number of dPCR platforms have been introduced commercially in recent years and more are being developed. These platforms differ in the method of partitioning, degree of automation, and multiplexing capabilities but all can be used in similar ways for sensitive and highly accurate quantification of a variety of nucleic acid targets. Currently, clinical applications of dPCR include oncology, microbiology and infectious disease, genetics, and prenatal/newborn screening. Commercially available tests for clinical applications are being developed for variants with diagnostic, prognostic, and therapeutic significance in specific disease types.

SUMMARY

The power of dPCR technology relies on the partitioning of the reactions and results in increased sensitivity and accuracy compared to qPCR. More recently, the sensitivity of dPCR has been applied to the detection of known variants in cell-free DNA and circulating tumor DNA. Future clinical applications of dPCR include liquid biopsy, treatment resistance detection, screening for minimal residual disease, and monitoring allograft engraftment in transplanted patients.

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.

ZNF384 fusion transcript levels for measurable residual disease monitoring in adult B-cell acute lymphoblastic leukemia

Zinc finger protein 384 (ZNF384) rearrangement defined a novel subtype of B-cell acute lymphoblastic leukemia (B-ALL). The prognostic significance of ZNF384 fusion transcript levels represented measurable residual disease remains to be explored. ZNF384 fusions were screened out in 57 adult B-ALL patients at diagnosis by real-time quantitative polymerase chain reaction and their transcript levels were serially monitored during treatment. The reduction of ZNF384 fusion transcript levels at the time of achieving complete remission had no significant impact on survival, whereas its ≥2.5-log reduction were significantly associated with higher relapse free survival (RFS) and overall survival (OS) rates after course 1 consolidation (p = 0.022 and = 0.0083) and course 2 consolidation (p = 0.0025 and = 0.0008). Compared with chemotherapy alone, allogeneic hematopoietic stem cell transplantation (allo-HSCT) significantly improved RFS and OS of patients with <2.5-log reduction after course 1 consolidation (p < 0.0001 and = 0.0002) and course 2 consolidation (p = 0.0003 and = 0.019), whereas exerted no significant effects in patients with ≥2.5-log reduction (all p > 0.05). ZNF384 fusion transcript levels after course 1 and course 2 consolidation strongly predict relapse and survival and may guide whether receiving allo-HSCT in adult B-ALL.

Clinical significance of flow cytometry in detection of minimal residual disease in cerebrospinal fluid

OBJECTIVES

Central nervous system leukemia (CNSL) is one of the main causes of recurrence and death in patients with acute leukemia. This study aims to dynamically monitor minimal residual disease (MRD) in cerebrospinal fluid and bone marrow of patients with different types of acute leukemia by flow cytometry (FCM), and to compare the timeliness and consistency of MRD detection between the 2 methods to further explore the application value of monitoring MRD in cerebrospinal fluid.

METHODS

A total of 199 patients with acute leukemia admitted to the Guangdong Provincial people's Hospital between October 2018 and January 2022 were retrospectively analyzed, and multiparametric FCM method was adopted to summarize and analyze MRD in cerebrospinal fluid of patients with different types of leukemia and MRD in cerebrospinal fluid and bone marrow specimens of the same patients, and its role in assessing the prognostic value of patients was discussed.

RESULTS

Among the 199 acute leukemia cases, a total of 31 cases (15.58%) were positive MRD in the cerebrospinal fluid, of which 18 cases (58%) were detected earlier than the corresponding bone marrow specimens. Among the 19 patients with acute T lymphoblastic leukemia, 134 patients with acute B lymphoblastic leukemia, and 46 patients with acute myeloid leukemia counted, there were 4, 18, and 9 patients with positive MRD in the cerebrospinal fluid. The Kappa value of the concordance test between the results of cerebrospinal fluid MRD and bone marrow MRD in different types of acute leukemia was only 0.156, demonstrating a low concordance between them.

CONCLUSIONS

Dynamic monitoring of cerebrospinal fluid MRD by FCM can be used as a monitoring index for central nervous system leukemia, and monitoring cerebrospinal fluid can detect MRD earlier compared with bone marrow, which complements each other as a sensitive index for evaluating prognosis with significant guidance in clinic.

A Review of Acute Lymphocytic Leukemia (ALL) in the Pediatric Population: Evaluating Current Trends and Changes in Guidelines in the Past Decade

Acute lymphocytic leukemia (ALL) is a commonly diagnosed cancer in children. Despite technological advancements to improve treatment and survival rates, there has been a steady increase in the incidence of ALL and treatment failures. This paper discusses the pathogenic interaction between genetic and environmental factors leading to childhood ALL. It evaluates the current treatment guidelines and notable obstacles leading to resistance, relapse, and treatment toxicities. The review evaluates a 10-year trend in the management guidelines of pediatric ALL through a systematic literature review of records from 2012 to 2023. Findings show that improvement in the five-year survival rates, notwithstanding rates of relapse and incurable diseases, is still high. Furthermore, several risk factors, including an interplay between genetic and environmental factors, are largely contributory to the outcome of ALL treatments and its overall incidence. Moreover, huge financial costs have remained a significant challenge in outcomes. There remains a need to provide individualized treatment plans, shared decision-making, and goals of care as parts of the management guidelines for the best possible outcomes. We expect that future advancements will increase overall survival rates and disease-free years.

The Role of Erythrocyte Sedimentation Rate (ESR) in Myeloproliferative and Lymphoproliferative Diseases: Comparison between DIESSE CUBE 30 TOUCH and Alifax Test 1

(1) Background: The erythrocyte sedimentation rate (ESR) is widely diffused in hematology laboratories to monitor inflammatory statuses, response to therapies (such as antibiotics), and oncologic diseases. However, ESR is not a specific diagnostic marker but needs to be contextualized and compared with clinical and other laboratory findings. This study aimed to investigate the performance of two automated instruments, namely the DIESSE CUBE 30 TOUCH (DIESSE, Siena, Italy) and the Alifax Test 1 (Alifax Srl, Polverara, Italy), in comparison with the gold standard, the Westergren method, in lymphoproliferative and myeloproliferative patients. (2) Methods: 97 EDTA samples were selected from the hematology department of Roma Tor Vergata Hospital and analyzed. Statistical analysis was applied. (3) A good correlation between CUBE 30 TOUCH and the gold standard was observed in the overall sample (R2 = 0.90), as well as in patients with lymphoproliferative diseases (R2 = 0.90) and myeloproliferative diseases (R2 = 0.90). The correlation between Test 1 and the gold standard was observed in the overall sample (R2 = 0.68), as well as in patients with lymphoproliferative diseases (R2 = 0.79) and myeloproliferative diseases (R2 = 0.53). (4) Conclusions: The CUBE 30 TOUCH appears to be a more trustworthy tool for evaluating ESR in these pathologies.

Low-dose anti-thymocyte globulin plus low-dose post-transplant cyclophosphamide-based regimen for prevention of graft-versus-host disease after haploidentical peripheral blood stem cell transplants: a large sample, long-term follow-up retrospective study

Introduction

The novel low-dose anti-thymocyte (ATG, 5 mg/kg) plus low-dose post-transplant cyclophosphamide (PTCy, 50 mg/kg) (low-dose ATG/PTCy)-based regimen had promising activity for prevention of graft-versus-host disease (GVHD) in haploidentical-peripheral blood stem cell transplantation (haplo-PBSCT), but its impacts on long-term outcomes remain to be defined.

Methods

We performed a large sample, long-term follow-up retrospective study to evaluate its efficacy for GVHD prophylaxis.

Results

The study enrolled 260 patients, including 162 with myeloid malignancies and 98 with lymphoid malignancies. The median follow-up time was 27.0 months. For the entire cohort, the cumulative incidences (CIs) of grade II-IV and III-IV acute GVHD (aGVHD) by 180 days were 13.46% (95% CI, 9.64%-17.92%) and 5.77% (95% CI, 3.37%-9.07%); while total and moderate/severe chronic GVHD (cGVHD) by 2 years were 30.97% (95% CI, 25.43%-36.66%) and 18.08% (95% CI, 13.68%-22.98%), respectively. The 2-year overall survival (OS), relapse-free survival (RFS), GVHD-free, relapse-free survival (GRFS), non-relapse mortality (NRM), and CIs of relapse were 60.7% (95% CI, 54.8%-67.10%), 58.1% (95% CI, 52.2%-64.5%), 50.6% (95% CI, 44.8-57.1%), 23.04% (95% CI, 18.06%-28.40%), and 18.09% (95% CI, 14.33%-23.97%, respectively. The 1-year CIs of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) reactivation were 43.46% (95% CI, 37.39%-49.37%) and 18.08% (95% CI, 13.68%-22.98%), respectively. In multivariate analysis, the disease status at transplantation was associated with inferior survivor outcomes for all patients and myeloid and lymphoid malignancies, while cGVHD had superior outcomes for all patients and myeloid malignancies, but not for lymphoid malignancies.

Discussion

The results demonstrated that the novel regimen could effectively prevent the occurrence of aGVHD in haplo-PBSCT.

Measurable Residual Disease (MRD) by Flow Cytometry in Adult B-Acute Lymphoblastic Leukaemia (B-ALL) and Acute Myeloid Leukaemia (AML): Correlation with Molecular MRD Testing and Clinical Outcome at One Year

Measurable residual disease (MRD) detected by flow cytometry (FC) is well established in paediatric B- lymphoblastic leukaemia (B-ALL) and adult chronic lymphocytic leukaemia (CLL), but its utility in adult B-ALL and adult acute myeloid leukaemia (AML) is less clear. In this prospective MRD study, one of the largest in Australia to date, we examined consecutive bone marrow aspirates from adult participants with B-ALL (n = 47) and AML (n = 87) sent for FC-MRD testing at a quaternary referral hospital in Sydney. FC-MRD results were correlated to corresponding Mol-MRD testing where available and clinical outcomes at three-month intervals over 1 year. B-ALL showed a moderate positive correlation (rs = 0.401, p < 0.001), while there was no correlation between FC-MRD and Mol-MRD for AML (rs = 0.13, p = 0.237). Five FC-MRD patterns were identified which had significant associations with relapse (X2(4) = 31.17(4), p > 0.001) and survival (X2(4) = 13.67, p = 0.008) in AML, but not in B-ALL. The three-month MRD results were also strongly associated with survival in AML, while the association in B-ALL was less evident. There was a moderate correlation between FC-MRD and Mol-MRD in B-ALL but not AML. The association of FC-MRD with relapse and survival was stronger in AML than in B-ALL. Overall, these findings suggest divergent utilities of FC-MRD in AML and B-ALL.

Impact of Minimal Residual Disease Detection by Next Generation Flow Cytometry on Outcome of Egyptian Patients with Acute Lymphoblastic Leukemia

INTRODUCTION

Recently, the identification of minimal residual disease (MRD) that persists after chemotherapy has emerged as the most powerful tool in determining the prognosis of patients with acute lymphoblastic leukemia (ALL). Multiple methods to detect MRD exist, each with its own benefits and drawback. Multiparameter flow cytometry and quantitative polymerase chain reaction are the most commonly used methods of MRD detection in clinical practice.

OBJECTIVE

to evaluate the impact of minimal residual disease detection by Next Generation Flow Cytometry on Outcome of Egyptian Patients with Acute Lymphoblastic Leukemia.

PATIENTS &METHODS

The study conducted on 93 patients with recently diagnosed acute lymphoblastic leukemia. MRD detection was evaluated during follow up of patient (at End of induction EOI and End of consolidation EOC by next generation flow cytometry.

RESULTS

Out of 93 patients, 28 (30%) had positive MRD at EOI. Age, BCR-ABL, risk assessment, and relapse had a substantial impact on MRD at EOI (P <0.005). Fourteen patients (17.9%) at EOC were MRD positive; age, hemoglobin, blast count at diagnosis, BCR-ABL, risk stratification, relapse and overall survival showed significant association.

CONCLUSION

Positive MRD was a major risk factor for predicting poor survival and relapse at both EOI and EOC by cox regression analysis.

Circulating Biomarkers Associated with the Diagnosis and Prognosis of B-Cell Progenitor Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is a hematological disease characterized by the dysfunction of the hematopoietic system that leads to arrest at a specific stage of stem cells development, suppressing the average production of cellular hematologic components. BCP-ALL is a neoplasm of the B-cell lineage progenitor. BCP-ALL is caused and perpetuated by several mechanisms that provide the disease with its tumor potential and genetic and cytological characteristics. These pathological features are used for diagnosis and the prognostication of BCP-ALL. However, most of these paraclinical tools can only be obtained by bone marrow aspiration, which, as it is an invasive study, can delay the diagnosis and follow-up of the disease, in addition to the anesthetic risk it entails for pediatric patients. For this reason, it is crucial to find noninvasive and accessible ways to supply information concerning diagnosis, prognosis, and the monitoring of the disease, such as circulating biomarkers. In oncology, a biomarker is any measurable indicator that demonstrates the presence of malignancy, tumoral behavior, prognosis, or responses to treatments. This review summarizes circulating molecules associated with BCP-ALL with potential diagnostic value, classificatory capacity during monitoring specific clinic features of the disease, and/or capacity to identify each BCP-ALL stage regarding its evolution and outcome of the patients with BCP-ALL. In the same way, we provide and classify biomarkers that may be used in further studies focused on clinical approaches or therapeutic target identification for BCP-ALL.

Twenty-four-color full spectrum flow cytometry panel for minimal residual disease detection in acute myeloid leukemia

Full spectrum flow cytometry brings a breakthrough for minimal residual disease (MRD) detection in acute myeloid leukemia (AML). We aimed to explore the role of a new panel in MRD detection. We established a 24-color full-spectrum flow cytometry panel. A tube of 24-color antibodies included CD45, CD117, CD34, HLA-DR, CD15, CD64, CD14, CD11c, CD11b, CD13, CD33, CD371, CD7, CD56, CD19, CD4, CD2, CD123, CD200, CD38, CD96, CD71, CD36, and CD9. We discovered that when a tube meets 26 parameters (24 colors), these markers were not only limited to the observation of MRD in AML, but also could be used for fine clustering of bone marrow cells. Mast cells, basophils, myeloid dendritic cells, and plasmacoid dendritic cells were more clearly observed. In addition, immune checkpoint CD96 had the higher expression in CD117+ myeloid naive cells and CD56dimNK cells, while had the lower expression in CD56briNK cells in AML-MRD samples than in normal bone marrow samples. CD200 expression was remarkably enhanced in CD117+ myeloid naive cells, CD4+ T cells, T cells, activated T cells, CD56dimNK cells, and CD56briNK cells in AML-MRD samples. Our results can be used as important basis for auxiliary diagnosis, prognosis judgment, treatment guidance, and immune regulation in AML.

The evolution of minimal residual disease: key insights based on a bibliometric visualization analysis from 2002 to 2022

Background

The topic of minimal residual disease (MRD) has emerged as a crucial subject matter in the domain of oncology in recent years. The detection and monitoring of MRD have become essential for the diagnosis, treatment, and prognosis of various types of malignancy.

Aims

The purpose of this study is to explore the research trends, hotspots, and frontiers of MRD in the last two decades through bibliometric analysis.

Methods

We employed Web of Science databases to carry out a bibliometric visualization analysis of research on 8,913 academic papers about MRD research from 2002 to 2022. VOSviewer, CiteSpace, RStudio, and a bibliometric online analysis platform were mainly used to conduct co-occurrence analysis and cooperative relationship analysis of countries/regions, institutions, journals, and authors in the literature. Furthermore, co-occurrence, co-citation, and burst analyses of keyword and reference were also conducted to generate relevant knowledge maps.

Results

In the past 20 years, the number of MRD research papers has presented an overall rising trend, going through three stages: a plateau, development, and an explosion. The output of articles in the United States was notably superior and plays a dominant role in this field, and the Netherlands had the highest average citation per article. The most productive and influential institution was the University of Texas MD Anderson Cancer Center. Blood published the most papers and was the most cited journal. A collection of leading academics has come to the fore in the research field, the most prolific of which is Kantarjian HM. It was found that the application of MRD in "acute myeloid leukemia", "acute lymphoblastic leukemia", "multiple myeloma", as well as the detection technology of MRD, are the research hotspots and frontiers in this domain. Furthermore, we analyzed the co-citation network of references and found that the top 10 co-cited references were all associated with MRD in hematological malignancies.

Conclusion

This bibliometric visualization analysis conducted a thorough exploration into the research hotspots and trends in MRD from 2002 to 2022. Our findings can aid researchers in recognizing possible collaborations, guiding future research directions, and fostering the growth of MRD detection and monitoring technologies.

Novel RUNX1 Variation in B-cell Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is a malignant disease of hematopoietic stem cells. B cell ALL (B-ALL) is characterized by highly proliferative and poorly differentiated progenitor B cells in the bone marrow. Chromosomal rearrangements, aberrant cell signaling, and mutations lead to dysregulated cell cycle and clonal proliferation of abnormal B cell progenitors. In this study, we aimed to examine hot spot genetic variations in the RUNX1, IDH2, and IL2RA genes in a group of (n=52) pediatric B-ALL. Sanger sequencing results revealed a rare RUNX1 variant p.Leu148Gln in one B-ALL patient with disease recurrence. Additionally, common intronic variations rs12358961 and rs11256369 of IL2RA were determined in two patients. None of the patients had the IDH2 variant. RUNX1, IDH2, and IL2RA variations were rare events in ALL. This study detected a novel pathogenic RUNX1 variation in a patient with a poor prognosis. Examining prognostically important genetic anomalies of childhood lymphoblastic leukemia patients and the signaling pathway components will pilot more accurate prognosis estimations.

Multiparameter flow cytometry and ClonoSEQ correlation to evaluate precursor B-lymphoblastic leukemia measurable residual disease

Measurable residual disease (MRD) detection for precursor B-lymphoblastic leukemia (B-ALL) has become the standard of care. However, the testing methodology has not been standardized. We aim to correlate COG multiparameter flow cytometry (MFC) and ClonoSEQ techniques to assess the test characteristics, to study abnormal immunophenotype for B-ALL MRD, and to observe B-ALL clonal evolution and the impact of blinatumomab therapy on MFC testing. MFC and molecular reports were retrieved from electronic medical records and data was reviewed. Included in this study were 74 bone marrow samples collected from 31 B-ALL patients at our institution between January 2021 and March 2022. COG MFC and ClonoSEQ results were concordant in 59/74 samples (80%) with positive concordant results in 12 samples (16%) and negative concordant results in 47 samples (64%). Discordant results were seen in 15/74 samples (20%), with 14 samples (19%) showing ClonoSEQ + /MFC- results and only 1 sample (1%) showing MFC + /ClonoSEQ- result. ClonoSEQ + /MFC- cases had MRD values ranging from 1 to 1400 cells/million nucleated cells with 86% of cases showing MRD values of < 100 cells/million nucleated cells. Newly identified dominant sequences were detected using ClonoSEQ in 2/31 patients (6%) during follow-up. All 14 bone marrow samples from 8 patients, who had gone through blinatumomab immunotherapy, were MRD negative by MFC, but 3 cases were MRD positive by ClonoSEQ. Our results show strong correlation between COG MFC and ClonoSEQ (r = 0.96), and both methods are complementary. Clonal evolution may occur, and blinatumomab immunotherapy may impact MFC B-ALL MRD evaluation.

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.

Liquid biopsies and minimal residual disease in lymphoid malignancies

Minimal residual disease (MRD) assessment using peripheral blood instead of bone marrow aspirate/biopsy specimen or the biopsy of the cancerous infiltrated by lymphoid malignancies is an emerging technique with enormous interest of research and technological innovation at the current time. In some lymphoid malignancies (particularly ALL), Studies have shown that MRD monitoring of the peripheral blood may be an adequate alternative to frequent BM aspirations. However, additional studies investigating the biology of liquid biopsies in ALL and its potential as an MRD marker in larger patient cohorts in treatment protocols are warranted. Despite the promising data, there are still limitations in liquid biopsies in lymphoid malignancies, such as standardization of the sample collection and processing, determination of timing and duration for liquid biopsy analysis, and definition of the biological characteristics and specificity of the techniques evaluated such as flow cytometry, molecular techniques, and next generation sequencies. The use of liquid biopsy for detection of minimal residual disease in T-cell lymphoma is still experimental but it has made significant progress in multiple myeloma for example. Recent attempt to use artificial intelligence may help simplify the algorithm for testing and may help avoid inter-observer variation and operator dependency in these highly technically demanding testing process.

Outcomes of allogeneic or autologous stem cell transplantation followed by maintenance chemotherapy in adult patient with B-ALL in CR1 with no detectable minimal residual disease

Autologous haematopoietic stem cell transplantation (auto-HSCT) as a treatment for B-cell acute lymphoblastic leukaemia (B-ALL) has been rigorously debated in recent years. We retrospectively analysed the outcomes of 355 adult patients with B-ALL in first complete remission who had received auto-HSCT or allogeneic HSCT (allo-HSCT) in our centre. The treatment efficacy was evaluated from a model stratified on the risk classification and minimal residue disease (MRD) status after three chemotherapy cycles. Auto-HSCT demonstrated comparable 3-year overall survival (OS) (72.7% vs. 68.5%, p = 0.441) and leukaemia-free survival rates (62.8% vs. 56.1%, p = 0.383) compared to allo-HSCT for patients with negative MRD, while the advantage of lower non-relapse mortality (1.5% vs. 25.1%, p < 0.001) was offset by a higher cumulative incidence of relapse (CIR) rates (35.7% vs. 18.9%, p = 0.018), especially in high-risk patients. For patients at high risk and with positive MRD, there was a lower trend of 3-year OS (50.0% vs. 66.0%, p = 0.078) and significantly higher CIR rates (71.4% vs. 39.1%, p = 0.018) in auto-HSCT. However, no significant interaction was observed in the tests. In conclusion, auto-HSCT appears to be an attractive treatment for patients with negative MRD after three chemotherapy cycles. For MRD-positive patients, allo-HSCT may be a more effective treatment.

Mutation of the TP53 gene in acute lymphoblastic leukemia does not affect survival outcomes after haploidentical hematopoietic stem cell transplantation

Previous studies have demonstrated that TP53 mutation is correlated with insufficient therapy response and unfavorable prognosis in acute lymphoblastic leukemia (ALL). Few studies have investigated the impact of TP53 mutation in ALL patients after haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We completed a retrospective study of 65 ALL patients with available TP53 status who underwent haplo-HSCT. They were divided into a TP53 mutation group (TP53^mut ) and a TP53 wild-type (TP53^wt ) group. TP53^mut showed comparable 2-year cumulative incidence of relapse (CIR) rates (13.1% vs 12.5%, P = .96) and 2-year leukemia-free survival (LFS) (74.2% vs 77.4%, P = .80) with TP53^wt . No significant differences in 2-year overall survival (OS) rates (82.9% vs 87.3%, P = .61) or 2-year NRM rates (12.7% vs 10.2%, P = .69) were observed in TP53^mut and TP53^wt patients. Multivariate analysis suggested that white blood cell (WBC) count at initial diagnosis (>50 × 10⁹ /L: hazard ratio [HR] = 3.860, P = .016) and age (>40 years old: HR = 4.120, P = .012) are independent risk factors for 2-year LFS. Our study showed that TP53 mutations may not be related to the unfavorable impact on survival in ALL patients after treatment with haplo-HSCT. The present results suggested that haplo-HSCT may eliminate the poor prognosis effect of TP53 mutation in ALL.

Recent Advances in Methods for Circulating Tumor Cell Detection

Circulating tumor cells (CTCs) are released from primary tumors and transported through the body via blood or lymphatic vessels before settling to form micrometastases under suitable conditions. Accordingly, several studies have identified CTCs as a negative prognostic factor for survival in many types of cancer. CTCs also reflect the current heterogeneity and genetic and biological state of tumors; so, their study can provide valuable insights into tumor progression, cell senescence, and cancer dormancy. Diverse methods with differing specificity, utility, costs, and sensitivity have been developed for isolating and characterizing CTCs. Additionally, novel techniques with the potential to overcome the limitations of existing ones are being developed. This primary literature review describes the current and emerging methods for enriching, detecting, isolating, and characterizing CTCs.

HLA-haploidentical hematopoietic stem cells transplantation with regulatory and conventional T-cell adoptive immunotherapy in pediatric patients with very high-risk acute leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) is still needed for many children with very high-risk acute leukemia. An HLA-haploidentical family donor is a suitable option for those without an HLA-matched donor. Here we present outcomes of a novel HLA-haploidentical HSCT (haplo-HSCT) strategy with adoptive immunotherapy with thymic-derived CD4⁺CD25⁺ FoxP3⁺ regulatory T cells (Tregs) and conventional T cells (Tcons) performed between January 2017 and July 2021 in 20 children with high-risk leukemia. Median age was 14.5 years (range, 4-21), 15 had acute lymphoblastic leukemia, 5 acute myeloid leukemia. The conditioning regimen included total body irradiation (TBI), thiotepa, fludarabine, cyclophosphamide. Grafts contained a megadose of CD34+ cells (mean 12.4 × 10⁶/Kg), Tregs (2 × 10⁶/Kg) and Tcons (0.5-1 × 10⁶/Kg). All patients achieved primary, sustained full-donor engraftment. Only one patient relapsed (5%). The incidence of non-relapse mortality was 15% (3/20 patients). Five/20 patients developed ≥ grade 2 acute Graft versus Host Disease (aGvHD). It resolved in 4 who are alive and disease-free; 1 patient developed chronic GvHD (cGvHD). The probability of GRFS was 60 ± 0.5% (95% CI: 2.1-4.2) (Fig. 6), CRFS was 79 ± 0.9% (95% CI: 3.2-4.9) as 16/20 patients are alive and leukemia-free. The median follow-up was 2.1 years (range 0.5 months-5.1 years). This innovative approach was associated with very promising outcomes of HSCT strategy in pediatric patients.

Transferring measurable residual disease measurement in pediatric acute lymphoblastic leukemia from quantitative real-time PCR to digital droplet PCR

BACKGROUND

Since the measurement of measurable residual disease (MRD) is part of clinical routine examination for children affected with acute lymphoblastic leukemia (ALL), continuous efforts are made to improve its method, applicability and accuracy. Whereas quantitative real-time polymerase chain reaction (qPCR) is considered as the gold standard for MRD detection and endowed with international guidelines for implementation and evaluation, these do not yet exist for digital droplet PCR (ddPCR). However, advantages are seen in droplet partitioning for MRD measurement to allow absolute quantification without depending on reference samples.

METHODS

In this study, 17 MRD targets of nine patients with childhood B-ALL were analyzed with qPCR and ddPCR, respectively. All patients were assigned to high risk group and had hematopoietic stem cell transplantation and CD19 antibody therapy for relapse prevention. Starting with the sequences and guidelines of qPCR and optimizing the protocol for ddPCR, the MRD targets could also be measured precisely with this novel method, using the same primer and probe sets as for qPCR.

RESULTS

The already established MRD protocol of qPCR could be transferred to ddPCR and all 17 MRD targets were measured in dilution series reaching comparable Limit of detection levels with both PCR methods.

CONCLUSIONS

With a given qPCR protocol and some experience in conventional MRD monitoring, it is conceivable to transfer the procedure of MRD measurement to ddPCR technology. Our data is in line with other studies which are summarized and discussed here as well to facilitate the transfer of MRD diagnostics to ddPCR.

Real-world utility of early measurable residual disease assessments by multi-parametric flow cytometry in adult patients with B-lymphoblastic leukemia receiving Hyper-CVAD induction chemotherapy

Multi-parametric flow cytometry (MFC) has a well-established role in measurable residual disease (MRD) monitoring in patients with B-lymphoblastic leukemia (B-ALL). However, the optimal time-point (TP) for early MRD testing and associated prognostic impact remain undefined in adult B-ALL patients receiving Hyper-CVAD induction chemotherapy. To evaluate the utility of MRD analysis after one cycle (TP1) in comparison to MRD analysis after two cycles (TP2) of induction treatment with Hyper-CVAD chemotherapy, we studied 49 adult B-ALL patients over a 10-year period (2010-2020) who had available bone marrow samples for morphological and MFC MRD assessments at the two separate TPs. Median times to TP1 and TP2 relative to start of treatment were 21 and 45 days, respectively. When censored at transplant, achievement of MRD negativity at TP1 was not associated with a statistically significant improvement in either event-free survival (EFS) (p = .426) or overall survival (OS) (p = .335) when compared to patients with MRD positivity. In contrast, achieving MRD negativity at TP2 was associated with a statistically significant improvement in both EFS (p = ·005) and OS (p = .047) over patients who remained MRD positive. Multivariate analysis demonstrated that KMT2A-rearrangement and MRD positivity at TP2 were the only significant predictors of outcome, correlating with worse EFS and OS. Therefore, in the absence of residual morphologic disease, MRD analysis after one cycle of Hyper-CVAD induction chemotherapy did not provide additional benefit with regard to risk stratification or correlation with survival outcomes when compared to MRD testing after two cycles of Hyper-CVAD in adult B-ALL patients.

Treatment for a B-cell acute lymphoblastic leukemia patient carrying a rare TP53 c.C275T mutation: A case report

TP53 mutations are associated with poor prognosis in the vast majority of cancers. In this study, we present a pediatric B-cell acute lymphoblastic leukemia (B-ALL) patient carrying a rare TP53 c.C275T mutation. This extremely rare mutation affects an amino acid residue located between the TAD domain and the DNA-binding domain of p53. The patient was resistant to most conventional chemotherapy regimens and remained minimal residual disease (MRD)-positive after five rounds of such regimens. We tested the sensitivity of the patient's leukemic cells to 21 anti-cancer drugs by performing in vitro drug sensitivity assays. The results showed that bortezomib had a very strong killing effect on the patient's leukemic cells. Therefore, we subsequently treated the patient with bortezomib combined with vindesine, cytarabine, and fludarabine. After one course of treatment, the patient became MRD-negative, and there was no recurrence during a 9-month follow-up. In conclusion, our report suggests that the TP53 c.C275T mutation is associated with poor prognosis in B-ALL. Fortunately, bortezomib combined with chemotherapy could achieve a better therapeutic effect than conventional regimens in this type of ALL.

CAR-T therapy followed by allogeneic hematopoietic stem cell transplantation for refractory/relapsed acute B lymphocytic leukemia: Long-term follow-up results

Background

Patients with refractory/relapsed (r/r) acute B lymphocytic leukemia (B-ALL) can achieve complete response (CR) after chimeric antigen receptor T-cell (CAR-T) therapy, but recurrence occurs in the short term. To reduce recurrence and improve survival, CAR-T therapy followed by transplantation is a feasible option. We analyzed the long-term follow-up outcomes and the risk factors for allogeneic hematopoietic stem cell transplantation (allo-HSCT) after CR by CAR-T therapy in this study.

Methods

A total of 144 patients who underwent allo-HSCT after CAR-T therapy in our hospital were enrolled in this study. Target gene analysis was performed in 137 r/r B-ALL patients receiving allo-HSCT after CR by CAR-T therapy. Among the 137 patients, 87 were evaluated for germline predisposition gene mutations, and 92 were evaluated for tumor somatic gene mutations using NGS. The clinical factors, germline predisposition gene and somatic gene mutations associated with the prognosis of patients receiving transplantation after CAR-T therapy were analyzed using univariate Cox regression. Factors related to disease-free survival (DFS) and overall survival (OS) were analyzed using multivariate Cox regression analysis.

Results

In 137 r/r B-ALL patients, the 2-year cumulative incidence of recurrence (CIR), OS and DFS in patients receiving allo-HSCT after CAR-T therapy was 31.5%, 71.4%, and 60.5%, respectively. The 2-year OS and DFS in MRD-negative patients were 80.9% and 69.3%, respectively. Univariate Cox analysis showed that pretransplant MRD positivity, fungal infection, germline EP300 mutation and somatic TP53 mutation were associated with a poor prognosis after transplantation; a TBI-based regimen was a protective factor for survival and recurrence after transplantation. Multivariate Cox regression analysis showed that the TBI-based regimen was an independent protective factor for DFS, fungal infection and MRD positivity were independent risk factors for DFS, and tumor somatic TP53 mutation and germline EP300 mutation were independent risk factors for DFS and OS.

Conclusion

Germline EP300 mutation and tumor somatic TP53 mutation are poor prognostic factors for posttransplant recurrence and survival in r/r B-ALL patients achieving CR after CAR-T therapy. The prognostic risk factors should be considered in adjusting treatment strategies to improve the efficacy of clinical diagnosis and treatment.

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.

Go with the Flow—Early Assessment of Measurable Residual Disease in Children with Acute Lymphoblastic Leukemia Treated According to ALL IC-BFM2009

Simple Summary

Monitoring of residual disease is a very important aspect of modern treatment approaches in many types of cancer. In acute leukemias in both children and adults, molecular and cytometric methods are used to assess the burden of leukemia at different points during therapy. Residual disease measured at the end of induction was shown to be the strongest predictor of outcome. Analyzing the outcomes of children with acute lymphoblastic leukemia (ALL), we aimed to establish the most informative cut-off and time point of assessment. Applying only the measurement of residual disease by flow cytometry along with genotypic findings, we managed to identify patients with a poor prognosis. Although new precise, molecular techniques as the next generation sequencing strategy are approaching daily clinical practice, flow cytometry is still a reliable, standardized method of residual disease detection. We may say ‘go with the flow’; thus, the assessment of residual disease by multiparametric flow cytometry is a proper method for the management of ALL patients according to risk-adapted therapies.

Abstract

Measurable residual disease (MRD) is a well-known tool for the evaluation of the early response to treatment in patients with acute lymphoblastic leukemia (ALL). In respect to predicting the relapse the most informative cut-off and time point of MRD measurement during therapy were evaluated in our study. Between 1 January 2013 and 31 December 2019, multiparametric flow cytometry (MFC) MRD was measured in the bone marrow of 140 children with ALL treated according to the ALL IC-BFM2009 protocol. The MRD cut-off of 0.1% and day 33, end of induction, were the most discriminatory for all patients. Patients with negative MRD on day 15 and 33 had a higher 5-year overall survival—OS (100%) and a higher relapse-free survival—RFS rate (97.6%) than those with positive levels of MRD (≥0.01%) at both time points (77.8% and 55.6%, p = 0.002 and 0.001, respectively). Most patients with residual disease below 0.1% on day 15 exhibit hyperdiploidy or ETV6-RUNX1 in ALL cells. Measurement of MRD at early time points can be used with simplified genetic analysis to better identify low and high-risk patients, allowing personalized therapies and further improvement in outcomes in pediatric ALL.

The kinetics of blast clearance are associated with copy number alterations in childhood B-cell acute lymphoblastic leukemia

We analyzed the pattern of whole-genome copy number alterations (CNAs) and their association with the kinetics of blast clearance during the induction treatment among 195 pediatric patients with B-cell precursor acute lymphoblastic leukemia (BCP-ALL) who displayed intermediate or high levels of minimal residual disease (MRD). Using unsupervised hierarchical clustering of CNAs > 5 Mbp, we dissected three clusters of leukemic samples with distinct kinetics of blast clearance [A - early slow responders (n=105), B - patients with persistent leukemia (n=24), C - fast responders with the low but detectable disease at the end of induction (n=66)] that corresponded with the patients' clinical features, the microdeletion profile,the presence of gene fusions and patients survival. Low incidence of large CNAs and chromosomal numerical aberrations occurred in cluster A which included ALL samples showing recurrent microdeletions within the genes encoding transcription factors (i.e., IKZF1, PAX5, ETV6, and ERG), DNA repair genes (XRCC3 and TOX), or harboring chromothriptic pattern of CNAs. Low hyperdiploid karyotype with trisomy 8 or hypodiploidy was predominantly observed in cluster B. Whereas cluster C included almost exclusively high-hyperdiploid ALL samples with concomitant mutations in RAS pathway genes. The pattern of CNAs influences the kinetics of leukemic cell clearance and selected aberrations affecting DNA repair genes may contribute to BCP-ALL chemoresistance.

The ALLgorithMM: How to define the hemodilution of bone marrow samples in lymphoproliferative diseases

Introduction

Minimal residual disease (MRD) is commonly assessed in bone marrow (BM) aspirate. However, sample quality can impair the MRD measurement, leading to underestimated residual cells and to false negative results. To define a reliable and reproducible method for the assessment of BM hemodilution, several flow cytometry (FC) strategies for hemodilution evaluation have been compared.

Methods

For each BM sample, cells populations with a well-known distribution in BM and peripheral blood - e.g., mast cells (MC), immature (IG) and mature granulocytes (N) – have been studied by FC and quantified alongside the BM differential count.

Results

The frequencies of cells’ populations were correlated to the IG/N ratio, highlighting a mild correlation with MCs and erythroblasts (R=0.25 and R=0.38 respectively, with p-value=0.0006 and 0.0000052), whereas no significant correlation was found with B or T-cells. The mild correlation between IG/N, erythroblasts and MCs supported the combined use of these parameters to evaluate BM hemodilution, hence the optimization of the ALLgorithMM. Once validated, the ALLgorithMM was employed to evaluate the dilution status of BM samples in the context of MRD assessment. Overall, we found that 32% of FC and 52% of Next Generation Sequencing (NGS) analyses were MRD negative in samples resulted hemodiluted (HD) or at least mildly hemodiluted (mHD).

Conclusions

The high frequency of MRD-negative results in both HD and mHD samples implies the presence of possible false negative MRD measurements, impairing the correct assessment of patients’ response to therapy and highlighs the importance to evaluate BM hemodilution.

Clinical implication of minimal residual disease assessment by next-generation sequencing-based immunoglobulin clonality assay in pediatric B-acute lymphoblastic leukemia

Measuring minimal residual disease (MRD) during treatment is valuable to identify acute lymphoblastic leukemia (ALL) patients who require intensified treatment to avert relapse. We performed the next-generation sequencing (NGS)-based immunoglobulin gene (Ig) clonality assay and evaluated its clinical implication in pediatric B-ALL patients to assess MRD. Fifty-five patients who were diagnosed and treated with de novo (n = 44) or relapsed/refractory B-ALL (n = 11) were enrolled. MRD assessment was performed using the LymphoTrack^® Dx IGH and IGK assay panels. The percentage of the clonal sequences per total read count was calculated as MRD (% of B cells). The data were normalized as the proportion of total nucleated cells (TNC) by LymphoQuant™ Internal control or the B-cell proportion in each sample estimated by flow cytometry or immunohistochemistry. Clonal Ig rearrangement was identified in all patients. The normalized MRD value was significantly lower than the unnormalized MRD value (p < 0.001). When categorizing patients, 27 of 50 patients (54%) achieved normalized MRD <0.01%, while 6 of them did not achieve MRD <0.01% when applying the unnormalized value. The normalized post-induction MRD value of 0.01% proved to be a significant threshold value for both 3-year event-free survival (100% for MRD <0.01% vs. 60.9% ± 10.2% for MRD ≥0.01%, p = 0.007) and 3-year overall survival (100% for MRD <0.01% vs. 78.3% ± 8.6% for MRD ≥0.01%, p = 0.011). However, unnormalized MRD was not a significant factor for outcome in this cohort. Our study demonstrated that MRD assessment by NGS-based Ig clonality assay could be applied in most pediatric B-ALL patients. Normalized post-induction MRD <0.01% was a significant prognostic indicator.

Changing Landscape in the Treatment of Adult Acute Lymphoblastic Leukemia (ALL)

Simple Summary

The improved understanding of acute lymphoblastic leukemia has brought with it several new therapy strategies as well as novel treatment agents. The aim of our review was to create a well-arranged overview of the currently available treatment strategies for ALL.

Abstract

Acute lymphoblastic leukemia (ALL) is a rare hematological malignancy characterized by proliferation and accumulation of premature lymphoid blasts. Depending on risk factors, the survival of acute lymphoblastic leukemia has significantly improved over the last decades. During the last years, measurable residual disease (MRD) assessment has evolved into one of the most sensitive markers for prognosis and risk of relapse. For this reason, measurable residual disease detection and monitoring count as standard evaluation in patients with acute lymphoblastic leukemia. Allogeneic stem cell transplantation is still the recommended treatment option for patients with high and highest risk profiles as well as for relapsed or refractory settings. The increased understanding of the pathomechanism and heterogeneity of acute lymphoblastic leukemia has led to the development of several novel therapeutic opportunities such as tyrosine-kinase inhibitors, antibody-based therapies and CAR-T cells with the aim of improving clinical outcomes. Furthermore, the major advances in disease understanding of ALL have led to the identification of different subgroups and better disease stratification. Even though novel therapy targets are constantly developed, acute lymphoblastic leukemia remains a challenging and life-threatening disease. To improve the historically unsatisfying result in therapy of adult acute lymphoblastic leukemia many clinical trials have recently been initiated to determine the optimum combination regimens of novel and old agents for adult acute lymphoblastic leukemia.

Clinical application of next-generation sequencing-based monitoring of minimal residual disease in childhood acute lymphoblastic leukemia

BACKGROUND

Next-generation sequencing (NGS) is an emerging technology that can comprehensively assess the diversity of the immune system. We explored the feasibility of NGS in detecting minimal residual disease (MRD) in childhood acute lymphoblastic leukemia (ALL) based on immunoglobulin and T cell receptor.

METHODS

Bone marrow samples were collected pre- and post-treatment with pediatric ALL admitted to Shenzhen Children's Hospital from February 1st, 2020 to January 31st, 2021. We analyzed the MRD detected by NGS, multiparametric flow cytometry (MFC) and real-time quantitative PCR (RQ-PCR), and analyzed risk factors of positive NGS-MRD at the end of B-ALL induction chemotherapy.

RESULTS

A total of paired 236 bone marrow samples were collected from 64 children with ALL (58 B-ALL and 6 T-ALL). The decrease in the clonal rearrangement frequency of IGH, IGK, and IGL was generally consistent after treatment. Positive MRD was detected in 57.5% (77/134) of B-ALL and 80% (12/15) of T-ALL by NGS after chemotherapy, which was higher than those detected by MFC and RQ-PCR. In B-ALL patients, MRD results detected by NGS were consistent with MFC (r = 0.708, p < 0.001) and RQ-PCR (r = 0.618, p < 0.001). At the end of induction, NGS-MRD of 40.4% B-ALL was > 0.01% and multivariate analysis indicated that ≧2 clonal rearrangement sequences before treatment were an independent factor of negative NGS-MRD.

CONCLUSIONS

NGS is more sensitive than MFC and RQ-PCR for MRD measurement. B-ALL children with ≧2 clonal rearrangements detected by NGS before treatment are difficult to switch to negative MRD after chemotherapy.

Longer Time Intervals From Symptom Onset to Diagnosis Affect the Overall Survival in Children With Acute Lymphoblastic Leukemia

BACKGROUND

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Early diagnosis and timely treatment are essential for effective cancer control and have been widely analyzed in childhood cancer. However, few studies have described the time to diagnosis and treatment in children with ALL. This study investigated delays in diagnosis and treatment initiation and their impact on survival.

METHODS

This retrospective cohort study included 419 patients 0 to 14 years old at a tertiary hospital between 2011 and 2015. The optimal cutoff values for delays were determined by X-tile software. The Kaplan-Meier method and Cox regression models were used to evaluate the impact of delays on survival.

RESULTS

The median diagnosis, treatment, and total delays were 21 (interquartile range [IQR]: 11-35), 4 (IQR: 2-7), and 26 (IQR: 16-43) days, respectively. The results of multivariate analyses showed that diagnosis delay, risk stratification, and minimal residual disease level were independent predictors for treatment outcome in childhood ALL.

CONCLUSIONS

These findings suggested that a longer time to diagnosis negatively affected the clinical outcome of childhood ALL. Reducing the time to diagnosis could help to improve survival in these patients.

Negative value of CD10-/CD34- immunophenotype in pediatric leukemia and development of a related cell line model for investigating drug resistance

PURPOSE

Appropriate sub-classification of leukemia according to the immunophenotypic characteristics of the malignant cells may improve therapeutic strategies. The aim of this study was to investigate the prognostic value of CD10/CD34 surface markers in pediatric acute lymphoblastic leukemia (pALL).

PATIENTS AND METHODS

A retrospective cohort study was performed in 79 children with ALL. Possible correlation between leukemia prognosis and CD10 CD34 immunophenotype was assessed using Kaplan-Meier and Cox regression analyses. A CD10- CD34- pre-B-ALL cell line was generated from a patient with resistant ALL. RN95 was characterized using light microscopy, immunophenotyping, karyotyping, and Western blotting. Drug sensitivity and resistant genes' expression profile were assessed using MTT and RT-PCR assays.

RESULTS

Kaplan-Meier analysis showed negative correlation between CD10/CD34 double negativity and patients' 2- and 5-year disease-free survival (DFS). Multivariate analysis indicated that the absence of CD10 and CD34 expression in the ALL patients was an independent negative prognostic marker for 2- and 5-year DFS. A novel cell line model, RN95, was developed with similar immunophenotype from a primary relapsed sample. Cells showed p53 positive functionality and demonstrated partial sensitivity to Vincristine, but complete resistance to Cytarabine. Overexpression of ABCB1, ABCA2, and ABCA3 was detected.

CONCLUSION

In the current study, simultaneous absence of CD10 and CD34 cell surface markers was introduced as an unfavorable prognostic factor in pediatric B-ALL. Moreover, a special cell line was established to help delineation of novel therapeutics for B-ALL drug resistance.

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.

The clinical characteristics and prognosis in adult Ph negative acute lymphoblastic leukemia with TP53 aberrations

Very few reports elucidate the prognosis of patients with TP53 aberrations using both measurable residual disease (MRD) and the status of having undergone allogeneic hematopoietic stem cell transplantation (allo-SCT). In this study, aberrations of TP53 were analyzed using next-generation sequencing (NGS) and fluorescence in situ hybridization (FISH) in patients with Philadelphia chromosome-negative (Ph^-) ALL enrolled in a prospective single-arm clinical trial at our leukemia center. We analyzed the survival of the patients grouped according to the MRD level at the third month and whether or not received allo-SCT. We found that allo-SCT could improve the OS in patients with TP53 aberrations; Patients having negative MRD at the third month still showed worse 3-year OS and 3-year DFS without undergoing allo-SCT, which is different from previous studies, moreover, the prognostic significance of TP53 deletions was as important as TP53 mutations, the importance of screening both TP53 deletions and mutations in adult Ph^- ALL at diagnosis should be emphasized.

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.

Prognostic significance of IKZF1 deletions and IKZF1plus profile in children with B-cell precursor acute lymphoblastic leukemia treated according to the ALL-IC BFM 2009 protocol

The strongest predictors of outcome in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL) are minimal residual disease (MRD) and specific molecular abnormalities. One unfavorable prognostic factor is the presence of IKZF1 gene aberrations, particularly when co-occurring with high MRD level at the end of induction treatment. The present study determines the predictive value of a recently-defined IKZF1-plus (IKZF1^plus ) microdeletion profile in 373 children with BCP-ALL treated according to the ALL-IC BFM 2009 protocol. IKZF1-wild type (IKZF1^wt ) patients demonstrated lower leukemic burden parameters than those carrying IKZF1 deletion (IKZF1^del [n=26, 7.0%]) or IKZF1^plus pattern (n=34, 9.1%): i) median blast percentage at diagnosis (78.0% vs. 86.9% vs. 86.0%; p=0.021); ii) median MRD level at day 15 of induction protocol (0.3% vs. 2.1% vs. 0.8%; p=0.011); iii) poor steroid response (7.6% vs. 26.5% vs. 12.5%; p=0.010). MRD level at day 33 (MRD33) exceeding 10^-4 was more frequently observed in both the IKZF1^del and IKZF1^plus subgroups than in IKZF1^wt patients (n=9 [36.0%] vs. n=13 [41.9%] vs. n=70 [24.0%], p=0.051). IKZF1^plus individuals showed a tendency for a lower MRD reduction between day 15 and 33 compared to IKZF1^del patients (p=0.124). IKZF1^del and IKZF1^plus patients showed decreased relapse-free survival (HR [95%CI] for IKZF1^wt as reference=2.72 [1.21-6.11] and 2.00 [0.87-4.49], respectively, p=0.023). Both genetic markers including IKZF1^del and IKZF1^plus microdeletion profile provide additional predictive value of treatment outcome in childhood BCP-ALL and may contribute to more efficient patient stratification; the same is true in MRD guided protocols, which are based on flow cytometric measurements on day 15 of induction protocol. This article is protected by copyright. All rights reserved.

Contemporary Challenges in Clinical Flow Cytometry: Small Samples, Big Data, Little Time

Background

Immunophenotypic analysis of cell populations by flow cytometry has an established role in primary diagnosis and disease monitoring of many hematologic diseases. A persistent problem in evaluation of specimens is suboptimal cell counts and low cell viability, which results in an undesirable rate of analysis failure. In addition, the increased amount of data generated in flow cytometry challenges existing data analysis and reporting paradigms.

Content

We describe current and emerging technological improvements in cell analysis that allow the clinical laboratory to perform multiparameter analysis of specimens, including those with low cell counts and other quality issues. These technologies include conventional multicolor flow cytometry and new high-dimensional technologies, such as spectral flow cytometry and mass cytometry that enable detection of over 40 antigens simultaneously. The advantages and disadvantages of each approach are discussed. We also describe new innovations in flow cytometry data analysis, including artificial intelligence-aided techniques.

Summary

Improvements in analytical technology, in tandem with innovations in data analysis, data storage, and reporting mechanisms, help to optimize the quality of clinical flow cytometry. These improvements are essential because of the expanding role of flow cytometry in patient care.

Application of Next-Generation Sequencing-Based Mutational Profiling in Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

Recent efforts to characterize hematologic cancers with genetic and molecular detail have largely relied on mutational profiling via next-generation sequencing (NGS). The application of NGS-guided disease prognostication and clinical decision making requires a basic understanding of sequencing advantages, pitfalls, and areas where clinical care might be enhanced by the knowledge generated. This article identifies avenues within the landscape of adult acute lymphoblastic leukemia (ALL) where mutational data hold the opportunity to enhance understanding of disease biology and patient care.

RECENT FINDINGS

NGS-based assessment of measurable residual disease (MRD) after ALL treatment allows for a sensitive and specific molecular survey that is at least comparable, if not superior, to existing techniques. Mutational assessment by NGS has unraveled complex signaling networks that drive pathogenesis of T-cell ALL. Sequencing of patients with familial clustering of ALL has also identified novel germline mutations whose inheritance predisposes to disease development in successive generations. While NGS-based assessment of hematopoietic malignancies often provides actionable information to clinicians, patients with acute lymphoblastic leukemia are left underserved due to a lack of disease classification and prognostication schema that integrate molecular data. Ongoing research is positioned to enrich the molecular toolbox available to clinicians caring for adult ALL patients and deliver new insights to guide therapeutic selection, monitor clinical response, and detect relapse.

Assessment of Clonotypic Rearrangements and Minimal Residual Disease in Lymphoid Malignancies: A Large Cancer Center Experience Using clonoSEQ

CONTEXT.—

Measurable (minimal) residual disease (MRD) is an independent prognostic factor for survival outcomes in patients with lymphoid and plasma cell malignancies and has been incorporated into consensus criteria regarding treatment response, strategy, and clinical trial endpoints. clonoSEQ (a next-generation sequencing [NGS]-MRD assay) uses multiplex polymerase chain reaction and NGS to identify clonotypic rearrangements at the immunoglobulin (Ig) H, IgK, IgL, T-cell receptor (TCR)-β, and TCR-γ loci, and translocated B-cell lymphoma 1/IgH and 2/IgH sequences for MRD assessment. Additionally, it can be used to confirm diagnoses of cutaneous T-cell lymphoma (CTCL).

OBJECTIVE.—

To review the technical aspects of our experience using the clonoSEQ Assay in routine clinical practice.

DESIGN.—

In this single-center experience, 390 patients with lymphoid and plasma cell malignancies were assessed with the NGS-MRD Assay at a central laboratory.

RESULTS.—

Median time from arrival of the shipment to initiation of the assay (defined as captured in Adaptive's secure tracking system) was 2.1 hours. Overall, 317 patients had 1 or more samples submitted for sequence identification. Of these, 290 (91.5%) had trackable sequences identified. The median calibration rate of samples by malignancy (where n ≥ 10 samples, excluding CTCL samples) was 88.1%, across a variety of fresh and archived sample sources (177 of 201 samples). TCR-β and/or TCR-γ clonotypes were identified in 40 of 95 samples (42.1%) from 66 patients with suspected CTCL.

CONCLUSIONS.—

This NGS-MRD Assay is a valuable and sensitive tool for monitoring MRD in patients with plasma cell and lymphoid malignancies and assisting in the diagnosis of CTCL.

Why Do Children with Acute Lymphoblastic Leukemia Fare Better Than Adults?

It is a new and exciting time for acute lymphoblastic leukemia (ALL). While nearly 50 years ago, only one in nine children with ALL survived with chemotherapy, nowadays nearly 90% of children have a chance of long-term survival. Adults with ALL, as well as the special category of adolescents and young adult (AYA) patients, are catching up with the new developments seen in children, but still their prognosis is much worse. A plethora of factors are regarded as responsible for the differences in treatment response, such as age, ethnicity, disease biology, treatment regimens and toxicities, drug tolerance and resistance, minimal residual disease evaluation, hematopoietic stem cell transplantation timing and socio-economic factors. Taking these factors into account, bringing pediatric-like protocols to adult patient management and incorporating new agents into frontline treatment could be the key to improve the survival rates in adults and AYA.

ALKBH5-mediated m6A-demethylation of USP1 regulated T-cell acute lymphoblastic leukemia cell glucocorticoid resistance by Aurora B

Recent studies evidence that ubiquitin-specific proteases (USPs) are associated with the occurrence and chemoresistance of T-cell acute lymphoblastic leukemia (T-ALL). N⁶ -methyladenosine (m6A) demethylase AlkB homolog 5 (ALKBH5) exerts a carcinogenic effect in human cancers and improves the mRNA stability of USPs. Whether ubiquitin-specific protease 1 (USP1) controls chemoresistance of T-ALL is unknown. Our study demonstrated that USP1 expression was upregulated in glucocorticoid (GC)-resistant T-ALL patients and cells (CEM-C1). High expression of USP1 was correlated to the poor prognosis in T-ALL patients. Silencing USP1 increased CEM-C1 cell sensitivity to dexamethasone (Dex), reduced cell invasion, promoted cell apoptosis, and ameliorated glucocorticoid receptor (GR) expression. USP1 mediated T-ALL chemoresistance by interacting with and deubiquitination of Aurora B. Overexpression of USP1 reversed the amelioration effect of Aurora B inhibitor on CEM-C1 cell resistance to Dex. Mechanistically, ALKBH5 enhanced USP1 expression by reducing m6A level and mRNA stability in USP1 mRNA transcript. Downregulation of ALKBH5 reduced the levels of USP1 and Aurora B, facilitated CEM-C1 cell sensitivity to Dex, apoptosis, and GR expression, suppressed cell invasion. However, overexpression of USP1 reversed all the effects of ALKBH5 on CEM-C1 cells. In vivo results showed that tail vein injection of sh-USP1 resulted in a significant prolongation of mouse survival, suppressed tumor growth, maintained the normal weight of mice, reduced USP1 expression and facilitated GR expression. In conclusion, inhibition of ALKBH5-mediated m6A modification decreased USP1 expression and downregulation of USP1 ameliorated GC resistance of T-ALL through suppressing Aurora B expression and elevating GR level.

Droplet digital PCR allows vector copy number assessment and monitoring of experimental CAR T cells in murine xenograft models or approved CD19 CAR T cell-treated patients

BACKGROUND

Genetically engineered chimeric antigen receptor (CAR) T lymphocytes are promising therapeutic tools for cancer. Four CAR T cell drugs, including tisagenlecleucel (tisa-cel) and axicabtagene-ciloleucel (axi-cel), all targeting CD19, are currently approved for treating B cell malignancies. Flow cytometry (FC) remains the standard for monitoring CAR T cells using a recombinant biotinylated target protein. Nevertheless, there is a need for additional tools, and the challenge is to develop an easy, relevant, highly sensitive, reproducible, and inexpensive detection method. Molecular tools can meet this need to specifically monitor long-term persistent CAR T cells.

METHODS

Based on 2 experimental CAR T cell constructs, IL-1RAP and CS1, we designed 2 quantitative digital droplet (ddPCR) PCR assays. By targeting the 4.1BB/CD3z (28BBz) or 28/CD3z (28z) junction area, we demonstrated that PCR assays can be applied to approved CD19 CAR T drugs. Both 28z and 28BBz ddPCR assays allow determination of the average vector copy number (VCN) per cell. We confirmed that the VCN is dependent on the multiplicity of infection and verified that the VCN of our experimental or GMP-like IL-1RAP CAR T cells met the requirement (< 5 VCN/cell) for delivery to the clinical department, similar to approved axi-cel or tisa-cel drugs.

RESULTS

28BBz and 28z ddPCR assays applied to 2 tumoral (acute myeloid leukemia (AML) or multiple myeloma (MM) xenograft humanized NSG mouse models allowed us to quantify the early expansion (up to day 30) of CAR T cells after injection. Interestingly, following initial expansion, when circulating CAR T cells were challenged with the tumor, we noted a second expansion phase. Investigation of the bone marrow, spleen and lung showed that CAR T cells disseminated more within these tissues in mice previously injected with leukemic cell lines. Finally, circulating CAR T cell ddPCR monitoring of R/R acute lymphoid leukemia or diffuse large B cell lymphoma (n = 10 for tisa-cel and n = 7 for axi-cel) patients treated with both approved CAR T cells allowed detection of early expansion, which was highly correlated with FC, as well as long-term persistence (up to 450 days), while FC failed to detect these events.

CONCLUSION

Overall, we designed and validated 2 ddPCR assays allowing routine or preclinical monitoring of early- and long-term circulating approved or experimental CAR T cells, including our own IL-1RAP CAR T cells, which will be evaluated in an upcoming phase I clinical trial.