A triple-probe FISH screening strategy for risk-stratified therapy of acute lymphoblastic leukaemia in low-resource settings

A Novel 5-Probe FISH Strategy is Better Equipped for a More Comprehensive and Cost-Effective Risk Stratification of BCP-ALL

OBJECTIVE

The modern treatment protocols in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) are based on the disease's genetic characteristics and response to treatment. We propose a novel five-probe FISH strategy to risk stratify the BCP-ALL and compare its ability with the triple trisomy probe strategy to detect high hyperdiploidy.

METHODS

All newly diagnosed BCP-ALL cases were investigated using a five-probe FISH panel that included probes targeting BCR::ABL1 fusion, ETV6::RUNX1 fusion, and break-apart probes for KMT2A, IgH, and CRLF2 rearrangements. Further, a selected number of cases were screened by the triple trisomy probe of 4p11/CEN10/17 (Zytovision, Bremerhaven, Germany) to identify aneuploidy.

RESULTS

Of the 380 patients of BCP-ALL screened (≤ 18 years: 57.9%; > 18 years: 42.1%) using this five-probe strategy, we could assign clinically relevant eight risk groups to almost two-thirds of the patients (similar to the available literature). Compared with the widely accepted triple trisomy probe strategy, we found concordant findings in 75.5% of the patients; the triple trisomy probe could not identify high hyperdiploidy in 24.5% of patients. We observed the presence of (non-CRLF2) IgH rearrangement in 5.3% of patients.

CONCLUSIONS

We conclude that the proposed five-probe FISH strategy is better equipped to more comprehensively risk stratify BCP-ALL patients, with an increased ability to identify high hyperdiploidy and a subset of Ph-like-BCP-ALL.

Fifth edition WHO classification: precursor lymphoid neoplasms, acute leukaemias of mixed or ambiguous lineage, myeloid/lymphoid neoplasms, and histiocytic and dendritic cell neoplasms, including strategies for application

The fifth edition of the WHO classification of haematolymphoid tumours (WHO-HEM5) introduces significant updates to the classification of acute lymphoblastic leukaemia, ALAL (including mixed phenotype acute leukaemia (MPAL)), myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions (MLN-TK), and histiocytic and dendritic cell neoplasms, reflecting the advances in the understanding of the genetic basis of these diseases. This review provides an overview of these changes, highlighting a shift to a more refined molecular-genetic approach. The incorporation of newly recognised genetic subtypes into the classification scheme underscores the evolving landscape of these entities. Challenges in diagnosing ALAL/MPAL and MLN-TK are discussed, along with recent insights into histiocytic and dendritic cell neoplasms, including newly defined entities such as ALK-positive histiocytosis.The review also explores the practical implications of WHO-HEM5, particularly in resource-limited settings, where comprehensive molecular testing may be unavailable. While morphology and immunohistochemistry remain essential diagnostic tools, strategic use of flow cytometry and targeted fluorescence in situ hybridisation can facilitate risk-adapted classification and improve survival in regions with limited resources and therapeutic options. Future large-scale studies are necessary to establish the diagnostic and prognostic value of these newly genetically defined entities for diverse healthcare environments, and to standardise guidelines in refining disease classification and optimising patient outcomes.

Clinical Outcomes of Pediatric Acute Lymphoblastic Leukemia in the Bajio Region of Mexico: A Retrospective Cohort Study

Acute lymphoblastic leukemia (ALL) is the most common cancer in childhood, and the Hispanic race has the highest incidence worldwide. Disparities in survival rates exist among different regions of the world. Due to this heterogeneity and possible differences in the outcomes within Mexico, the aim of this study was to analyze the clinical outcomes of cohort of pediatric patients with ALL treated in a highly specialized medical unit located in the Bajio region of Mexico. Observational retrospective study of a cohort of pediatric patients with ALL treated in a tertiary-level hospital in the Bajio region of Mexico, between January 2016 and December 2021. A total of 146 patients were included with a median age of 7 years. The 68.5% of patients were at high risk. CNS involvement was present in 2.7%, and Philadelphia chromosome positive in 2%. Cytogenetic analysis was performed in 16.4% patients. The median follow-up of entire cohort was 32 months. The most frequently administered chemotherapy treatment was Total Therapy XV in 79.5% of patients. The complete remission rate was 89%. Refractory disease was present in 2.7%. Induction-related mortality was 8.2%. The relapse rate was present in 26%. The 3-years overall survival was 57.5%, and the 3-years event-free survival was 53.4%. A more aggressive course and worse survival occur in our cohort of pediatric patients with ALL. Strategies should be proposed inside Mexico and other low-middle income countries with the aim of improving the overall survival.

Role of Interphase FISH Assay on Air-Dried Smears in Identifying Specific Structural Chromosomal Abnormalities among Pediatric Patients with Acute Leukemias

Leukemia-associated structural chromosomal abnormalities (SCA) can be identified either by karyotyping or interphase-fluorescence in-situ hybridization (i-FISH) assays. Both karyotyping and i-FISH on mononuclear cell suspension are time, resource, and manpower-consuming assays. In this study, we have compared the results of specific leukemia-associated SCAs identified by i-FISH on air-dried bone marrow (BM)/peripheral blood (PB) smears and BM karyotyping. The study was conducted among pediatric patients (age ≤ 18 years) diagnosed with acute leukemias between January 2018 to December 2022. The results of i-FISH on air-dried BM/PB smears and BM-karyotyping for our SCA of interest (BCR::ABL1, ETV6::RUNX1, TCF3::PBX1, KMT2A rearrangement, RUNX1::RUNX1T1, CBFB::MYH11, and PML::RARA) were entered in a contingency table and the agreement of results was calculated. The strength of agreement was assessed by Cramer's V test. Among 270 patients, SCA of interest was identified among 26% and 17% of patients by i-FISH on air-dried smears and karyotyping, respectively. Excluding 53 patients with metaphase failure, the remaining 217 patients had 92% agreement (Cramer's V of 0.931 with p < 0.000) between the results for specific SCAs identified by both techniques. On excluding samples with cryptic cytogenetic aberrancies, there was 99% agreement (Cramer's V of 0.953 with p < 0.000) for gross SCA identified by both techniques. In addition, i-FISH on air-dried smears identified SCA in 30% of patients with metaphase failure. I-FISH on air-dried PB/BMA smears is a less-labor and  resource-consuming assay. It can be considered an efficient alternative to conventional karyotyping for  identifying specific SCA of interest in under-resourced laboratories.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12288-023-01699-2.

Comparative treatment costs of risk-stratified therapy for childhood acute lymphoblastic leukemia in India

BACKGROUND

To evaluate the treatment cost and cost effectiveness of a risk-stratified therapy to treat pediatric acute lymphoblastic leukemia (ALL) in India.

METHODS

The cost of total treatment duration was calculated for a retrospective cohort of ALL children treated at a tertiary care facility. Children were risk stratified into standard (SR), intermediate (IR) and high (HR) for B-cell precursor ALL, and T-ALL. Cost of therapy was obtained from the hospital electronic billing systems and details of outpatient (OP) and inpatient (IP) from electronic medical records. Cost effectiveness was calculated in disability-adjusted life years.

RESULTS

One hundred and forty five patients, SR (50), IR (36), HR (39), and T-ALL (20) were analyzed. Median cost of the entire treatment for SR, IR, HR, and T-ALL was found to be $3900, $5500, $7400, and $8700, respectively, with chemotherapy contributing to 25%-35% of total cost. Out-patient costs were significantly lower for SR (p < 0.0001). OP costs were higher than in-patient costs for SR and IR, while in-patient costs were higher in T-ALL. Costs for non-therapy admissions were significantly higher in HR and T-ALL (p < 0.0001), representing over 50% of costs of in-patient therapy. HR and T-ALL also had longer durations of non-therapy admissions. Based on WHO-CHOICE guidelines, the risk-stratified approach was very cost effective for all categories of patients.

CONCLUSIONS

Risk-stratified approach to treat childhood ALL is very cost-effective for all categories in our setting. The cost for SR and IR patients is significantly reduced through decreased IP admissions for both, chemotherapy and non-chemotherapy reasons.

Protocol for ICiCLe-ALL-14 (InPOG-ALL-15-01): a prospective, risk stratified, randomised, multicentre, open label, controlled therapeutic trial for newly diagnosed childhood acute lymphoblastic leukaemia in India

Background

In the west, survival following treatment of childhood acute lymphoblastic leukaemia (ALL) approaches 90%. Outcomes in India do not exceed 70%. To address this disparity, the Indian Collaborative Childhood Leukaemia group (ICiCLe) developed in 2013 a contemporary treatment protocol for uniform risk-stratified management of first presentation ALL based on cytogenetics and minimal residual disease levels (MRD). A multicentre randomised clinical trial opened in 2016 (ICiCLe-ALL-14) and examines the benefit of randomised interventions to decrease toxicity and improve outcomes.

Methods

Patients 1–18 years with newly diagnosed ALL are categorised into four risk groups based on presentation features, tumour genetics and treatment response. Standard risk includes young (< 10 years) B cell precursor ALL (BCP-ALL) patients with low presentation leucocyte count (< 50 × 109/L) and no high-risk features. Intermediate risk includes BCP-ALL patients with no high-risk features but are older and have high presentation leucocyte counts and/or bulky disease. High risk includes BCP-ALL patients with any high-risk feature, including high-risk genetics, central nervous system leukaemia, poor prednisolone response at treatment day 8 and high MRD (≥ 0·01%) at the end of induction. Patients with T-lineage ALL constitute the fourth risk group. All patients receive four intensive treatment blocks (induction, consolidation, interim maintenance, delayed intensification) followed by 96 weeks of maintenance. Treatment intensity varies by risk group. Clinical data management is based on a web-based remote data capture system. The first randomisation examines the toxicity impact of a shorter induction schedule of prednisolone (3 vs 5 weeks) in young non-high-risk BCP-ALL. The second randomisation examines the survival benefit of substituting doxorubicin with mitoxantrone in delayed intensification for all patients. Primary outcome measures include event-free survival (overall, by risk groups), sepsis rates in induction (first randomisation) and event-free survival rates following second randomisation.

Discussion

ICiCLe-ALL-14 is the first multicentre randomised childhood cancer clinical trial in India. The pre-trial phase allowed standardisation of risk-stratification diagnostics and established the feasibility of collaborative practice, uniform treatment, patient enrolment and data capture. Pre-trial observations confirm the impact of risk-stratified therapy in reducing treatment-related deaths and costs. Uniform practice across centres allows patients to access care locally, potentially decreasing financial hardship and dislocation.

Trial registration

Clinical Trials Registry-India (CTRI) CTRI/2015/12/006434. Registered on 11 December 2015

A Systematic Cytogenetic Strategy to Identify Masked Hypodiploidy in Precursor B Acute Lymphoblastic Leukemia in Low Resource Settings

Hypodiploidy with < 40 chromosomes is associated with poor prognosis in B cell precursor acute lymphoblastic leukemia. In some patients, the hypodiploid clone undergoes endoreduplication, resulting in doubling of the number of chromosomes and masquerades as a high hyperdiploid BCP-ALL. Karyotyping reveals metaphases with 50-79 chromosomes masking the hypodiploid clone. Identifying hypodiploidy in such cases requires awareness of non random alterations of chromosomal copy numbers found in hypodiploid BCP-ALL. We used a systematic strategy to identify masked hypodiploidy integrating targeted fluorescence in situ hybridization (FISH) analysis directed towards identifying monosomies of chromosomes 7, 15 and 17 and flow cytometry-based ploidy analysis (FCPA). Of 445 patients diagnosed as BCP ALL, 2.9% (13/445) were classified as hypodiploid including patients with masked hypodiploidy. Karyotype analysis showed hypodiploidy in 3 patients, near triploidy in 4 patients and normal karyotype in 6 patients. Four patients with near triploid clone on karyotype showed either bimodal peak (2 patients) or single low hypodiploid peak (1 patient) or only near triploid peak (1 patient) on FCPA. All 6 patients with normal karyotype revealed either bimodal peak (4 patients) or hypodiploid peak (2 patients) on FCPA. Targeted FISH analysis unmasked hypodiploid clone showing monosomies of chromosomes 7, 15 and 17 in all ten patients. Our algorithm successfully identified masked hypodiploidy in patients, including those with endoreduplication (4 patients) and normal karyotype (6 patients). Integrating FCPA with targeted FISH analysis provides a practical, sensitive and specific approach to identify masked hypodiploidy in low resource settings.

Curing the Curable: Managing Low-Risk Acute Lymphoblastic Leukemia in Resource Limited Countries

Although childhood acute lymphoblastic leukemia (ALL) is curable, global disparities in treatment outcomes remain. To reduce these global disparities in low-middle income countries (LMIC), a paradigm shift is needed: start with curing low-risk ALL. Low-risk ALL, which accounts for >50% of patients, can be cured with low-toxicity therapies already defined by collaborative studies. We reviewed the components of these low-toxicity regimens in recent clinical trials for low-risk ALL and suggest how they can be adopted in LMIC. In treating childhood ALL, the key is risk stratification, which can be resource stratified. NCI standard-risk criteria (age 1–10 years, WBC < 50,000/uL) is simple yet highly effective. Other favorable features such as ETV6-RUNX1, hyperdiploidy, early peripheral blood and bone marrow responses, and simplified flow MRD at the end of induction can be added depending on resources. With limited supportive care in LMIC, more critical than relapse is treatment-related morbidity and mortality. Less intensive induction allows early marrow recovery, reducing the need for intensive supportive care. Other key elements in low-toxicity protocol designs include: induction steroid type; high-dose versus low-dose escalating methotrexate; judicious use of anthracyclines; and steroid pulses during maintenance. In summary, the first effective step in curing ALL in LMIC is to focus on curing low-risk ALL with less intensive therapy and less toxicity.

An Evaluation of a Fluorescence In Situ Hybridization Strategy Using Air-dried Blood and Bone-marrow Smears in the Risk Stratification of Pediatric B-Lineage Acute Lymphoblastic Leukemia in Resource-limited Settings

Cytogenetic abnormalities (CAs), one of the strongest influencers of therapeutic outcome in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL), can be identified by different techniques. Despite several technological advances, many centers with resource-limited settings continue to use either reverse-transcriptase polymerase chain reaction (RT-PCR) and/or fluorescence in situ hybridization (FISH) to identify prognostically relevant CAs. We evaluated a simple and cost-effective triple-probe FISH strategy on air-dried blood and bone-marrow smears and compared its performance with a multiplex RT-PCR-based approach in the prognostication of pediatric BCP-ALL patients. Three hundred twenty BCP-ALL patients were tested prospectively and in parallel by FISH on air-dried blood or bone-marrow smears and RT-PCR. The FISH strategy correctly diagnosed all genetic abnormalities identified by RT-PCR. Prognostically relevant genetic abnormalities were missed by RT-PCR in 24 (8.1%) patients. In another 20 children (6%), with samples inadequate for RT-PCR testing (dry taps or due to poor sample quality), a successful FISH testing could be performed on bone-marrow aspirate or trephine-imprint smears. In addition, FISH detected ploidy changes, which could be confirmed by FxCycle Violet-based flow-cytometry. FISH testing on air-dried smears identified more prognostically relevant CAs, provided information on the ploidy status, and could be successfully performed in children with difficulty in bone-marrow sampling.

Recent Advances in Molecular Diagnosis and Prognosis of Childhood B Cell Lineage Acute Lymphoblastic Leukemia (B-ALL)

B cell lineage acute lymphoblastic leukemia is the most common leukemia occurring in children and young adults and is the leading cause of cancer related deaths. The 5 year overall survival outcome in children with B-ALL has improved significantly in the last few decades. In the past, the discovery of various genetic alterations and targeted therapy have played a major role in decreasing disease-related deaths. In addition, numerous advances in the pathogenesis of B-ALL have been found which have provided better understanding of the genes involved in disease biology with respect to diagnostic and prognostic implications. Present review will summarize current understanding of risk stratification, genetic factors including cytogenetics in diagnosis and prognosis of B-ALL.

Blast size-specific flowcytometric ploidy assessment using FxCycleTM Violet dye and its correlation with conventional cytogenetic ploidy in pediatric precursor B-lineage acute lymphoblastic leukemia patients

INTRODUCTION

Numerical chromosomal abnormalities (aneuploidies), present in approximately 30%-50% of pediatric precursor B-lineage acute lymphoblastic leukemia (B-ALL) patients, are commonly identified through a laborious conventional cytogenetic (CG) technique. Flow cytometry (FCM) can identify both physical and fluorescent properties of cells together, and by using fluorescent nucleic-acid-binding dyes, FCM can identify variations in total nucleic-acid content of cells. FxCycle^TM Violet dye (FxCV) is a selective DNA-binding dye which permits simultaneous multiparametric immunophenotyping and cell-cycle/ploidy assessment in a single assay. To date, only two studies have demonstrated the feasibility of FxCV-aided FCM-ploidy analysis in B-ALL patients and only one of these studies have compared their results with CG-ploidy.

METHODOLOGY

Blast size-specific FCM-ploidy was prospectively analyzed using FxCV-dye in 109 pediatric B-ALL patients, and the results were compared with concurrent CG-ploidy status.

RESULTS

FCM-ploidy categorization was feasible in 98% of samples tested and the results were 82% concordant with CG-ploidy status. We observed significant correlation between DNA content and blast size (r = .823, P < .001) and could demonstrate size differences between diploid vs low-hyperdiploid (P = .025), diploid vs high-hyperdiploid (P < .001) and low- vs high-hyperdiploid blasts (P = .007).

CONCLUSION

FCM-ploidy assessment using FxCV dye is a reliable assay and the results closely concur with CG-based ploidy stratification and risk assessment. Using blast size-assisted DNA content analysis, the results of FCM-ploidy analysis can be further fine-tuned.