Measuring response to therapy in AML: Difference from normal flow cytometry vs RQ-PCR.

Multiple technologies have been used to monitor response to therapy in acute myeloid leukemia (AML) to improve detection of leukemia over the standard of practice, morphologic counting of blasts. The two techniques most frequently used in a routine clinical setting, flow cytometry and RQ-PCR, differ in their targets, sensitivity, and ability to detect residual disease. Both flow cytometry and RQ-PCR detect the expression of abnormal gene products, at the protein level or RNA level, respectively. Flow cytometry can be applied to a broad range of AML cases while RQ-PCR is limited to specific genetic abnormalities identified in subsets of AML. This article compares the results when both techniques were used in a reference laboratory to monitor AML over the course of treatment, comparing quantitative and qualitative results.

[The value of minimal residual disease and IKZF1 deletion for predicting prognosis in adult patients with B-cell acute lymphoblastic leukemia].

Objective: To reassess the prognostic value of minimal residual disease (MRD) and IKZF1 gene deletions in adults with B-cell acute lymphoblastic leukemia (B-ALL) who received pediatric-specific chemotherapy regimens during the Nanfang Hospital PDT-ALL-2016 trial. Methods: We retrospectively analyzed the prognosis of 149 adult patients with B-ALL who were admitted to Nanfang Hospital from January 2016 to September 2020. Prognostic factors were identified using Cox regression models. Results: The complete remission rate was 93.2% in 149 patients, with a 5-year overall survival (OS) rate of (54.3±5.0) % and a cumulative incidence of relapse (CIR) of (47.5±5.2) %. The Cox regression analysis revealed that MRD positivity at day 45 (MRD(3)) after induction therapy was independently associated with relapse risk (HR=2.535, 95%CI 1.122-5.728, P=0.025). Deletion of IKZF1 gene was independently associated with mortality risk (HR=1.869, 95%CI 1.034-3.379, P=0.039). Based on MRD(3) and IKZF1 gene status, we categorized adult patients with B-ALL into the low-risk (MRD(3)-negative and IKZF1 gene deletion-negative) and high-risk (MRD(3)-positive and/or IKZF1 gene wild type) groups. The 5-year OS and CIR rates were (45.5±6.0) % vs (69.4±8.6) % (P<0.001) and (61.6±8.3) % vs (25.5±6.5) % (P<0.001), respectively, in the high-risk and low-risk groups, respectively. The multivariate analysis showed that the high-risk group was an independent risk factor for OS (HR=3.937, 95%CI 1.975-7.850, P<0.001) and CIR (HR=4.037, 95%CI 2.095-7.778, P<0.001) . Conclusion: The combined use of MRD and IKZF1 gene in prognostic stratification can improve clinical outcome prediction in adult patients with B-ALL, helping to guide their treatment.

Flow cytometric minimal residual disease measurement accounting for cytogenetics in children with non-high-risk acute lymphoblastic leukemia treated according to the ALL-MB 2008 protocol.

BACKGROUND: Quantitative measurement of minimal residual disease (MRD) is the "gold standard" for estimating the response to therapy in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Nevertheless, the speed of the MRD response differs for different cytogenetic subgroups. Here we present results of MRD measurement in children with BCP-ALL, in terms of genetic subgroups with relation to clinically defined risk groups. METHODS: A total of 485 children with non-high-risk BCP-ALL with available cytogenetic data and MRD studied at the end-of-induction (EOI) by multicolor flow cytometry (MFC) were included. All patients were treated with standard-risk (SR) of intermediate-risk (ImR) regimens of "ALL-MB 2008" reduced-intensity protocol. RESULTS AND DISCUSSION: Among all study group patients, 203 were found to have low-risk cytogenetics (ETV6::RUNX1 or high hyperdiploidy), while remaining 282 children were classified in intermediate cytogenetic risk group. For the patients with favorable and intermediate risk cytogenetics, the most significant thresholds for MFC-MRD values were different: 0.03% and 0.04% respectively. Nevertheless, the most meaningful thresholds were different for clinically defined SR and ImR groups. For the SR group, irrespective to presence/absence of favorable genetic lesions, MFC-MRD threshold of 0.1% was the most clinically valuable, although for ImR group the most informative thresholds were different in patients from low-(0.03%) and intermediate (0.01%) cytogenetic risk groups. CONCLUSION: Our data show that combining clinical risk factors with MFC-MRD measurement is the most useful tool for risk group stratification of children with BCP-ALL in the reduced-intensity protocols. However, this algorithm can be supplemented with cytogenetic data for part of the ImR group.

Bridging horizons beyond CIRCULATE-Japan: a new paradigm in molecular residual disease detection via whole genome sequencing-based circulating tumor DNA assay.

Circulating tumor DNA (ctDNA) is the fraction of cell-free DNA in patient blood that originates from a tumor. Advances in DNA sequencing technologies and our understanding of the molecular biology of tumors have increased interest in exploiting ctDNA to facilitate detection of molecular residual disease (MRD). Analysis of ctDNA as a promising MRD biomarker of solid malignancies has a central role in precision medicine initiatives exemplified by our CIRCULATE-Japan project involving patients with resectable colorectal cancer. Notably, the project underscores the prognostic significance of the ctDNA status at 4 weeks post-surgery and its correlation to adjuvant therapy efficacy at interim analysis. This substantiates the hypothesis that MRD is a critical prognostic indicator of relapse in patients with colorectal cancer. Despite remarkable advancements, challenges endure, primarily attributable to the exceedingly low ctDNA concentration in peripheral blood, particularly in scenarios involving low tumor shedding and the intrinsic error rates of current sequencing technologies. These complications necessitate more sensitive and sophisticated assays to verify the clinical utility of MRD across all solid tumors. Whole genome sequencing (WGS)-based tumor-informed MRD assays have recently demonstrated the ability to detect ctDNA in the parts-per-million range. This review delineates the current landscape of MRD assays, highlighting WGS-based approaches as the forefront technique in ctDNA analysis. Additionally, it introduces our upcoming endeavor, WGS-based pan-cancer MRD detection via ctDNA, in our forthcoming project, SCRUM-Japan MONSTAR-SCREEN-3.

Refining risk stratification in paediatric B-acute lymphoblastic leukaemia: Combining IKZF1plus and Day 15 MRD positivity.

This study investigates the potential utility of IKZF1 deletion as an additional high-risk marker for paediatric acute lymphoblastic leukaemia (ALL). The prognostic impact of IKZF1 status, in conjunction with minimal/measurable residual disease (MRD), was evaluated within the MRD-guided TPOG-ALL-2013 protocol using 412 newly diagnosed B-ALL patients aged 1-18. IKZF1 status was determined using multiplex ligation-dependent probe amplification. IKZF1 deletions, when co-occurring with CDKN2A, CDKN2B, PAX5 or PAR1 region deletions in the absence of ERG deletions, were termed IKZF1plus. Both IKZF1 deletion (14.6%) and IKZF1plus (7.8%) independently predicted poorer outcomes in B-ALL. IKZF1plus was observed in 4.1% of Philadelphia-negative ALL, with a significantly lower 5-year event-free survival (53.9%) compared to IKZF1 deletion alone (83.8%) and wild-type IKZF1 (91.3%) (p < 0.0001). Among patients with Day 15 MRD ≥0.01%, provisional high-risk patients with IKZF1plus exhibited the worst outcomes in event-free survival (42.0%), relapse-free survival (48.0%) and overall survival (72.7%) compared to other groups (p < 0.0001). Integration of IKZF1plus and positive Day 15 MRD identified a subgroup of Philadelphia-negative B-ALL with a 50% risk of relapse. This study highlights the importance of assessing IKZF1plus alongside Day 15 MRD positivity to identify patients at increased risk of adverse outcomes, potentially minimizing overtreatment.

Usefulness of KIT mutant transcript levels for monitoring measurable residual disease in t (8;21) acute myeloid leukemia.

In addition to RUNX1::RUNX1T1 transcript levels, measurable residual disease monitoring using KIT mutant (KITmut ) DNA level is reportedly predictive of relapse in t (8; 21) acute myeloid leukemia (AML). However, the usefulness of KITmut transcript levels remains unknown. A total of 202 bone marrow samples collected at diagnosis and during treatment from 52 t (8; 21) AML patients with KITmut (D816V/H/Y or N822K) were tested for KITmut transcript levels using digital polymerase chain reaction. The individual optimal cutoff values of KITmut were identified by performing receiver operating characteristics curve analysis for relapse at each of the following time points: at diagnosis, after achieving complete remission (CR), and after Course 1 and 2 consolidations. The cutoff values were used to divide the patients into the KITmut -high (KIT_H) group and the KITmut -low (KIT_L) group. The KIT_H patients showed significantly lower relapse-free survival (RFS) and overall survival (OS) rates than the KIT_L patients after Course 1 consolidation (p = 0.0040 and 0.021, respectively) and Course 2 consolidation (p = 0.018 and 0.011, respectively) but not at diagnosis and CR. The <3-log reduction in the RUNX1::RUNX1T1 transcript levels after Course 2 consolidation was an independent adverse prognostic factor for RFS and OS. After Course 2 consolidation, the KIT_H patients with >3-log reduction in the RUNX1::RUNX1T1 transcript levels (11/45; 24.4%) had similar RFS as that of patients with <3-log reduction in the RUNX1::RUNX1T1 transcript levels. The combination of KITmut and RUNX1::RUNX1T1 transcript levels after Course 2 consolidation may improve risk stratification in t (8; 21) AML patient with KIT mutation.

Application of droplet digital PCR in minimal residual disease monitoring of rare fusion transcripts and mutations in haematological malignancies.

Leukaemia of various subtypes are driven by distinct chromosomal rearrangement or genetic abnormalities. The leukaemogenic fusion transcripts or genetic mutations serve as molecular markers for minimal residual disease (MRD) monitoring. The current study evaluated the applicability of several droplet digital PCR assays for the detection of these targets at RNA and DNA levels (atypical BCR::ABL1 e19a2, e23a2ins52, e13a2ins74, rare types of CBFB::MYH11 (G and I), PCM1::JAK2, KMT2A::ELL2, PICALM::MLLT10 fusion transcripts and CEBPA frame-shift and insertion/duplication mutations) with high sensitivity. The analytical performances were assessed by the limit of blanks, limit of detection, limit of quantification and linear regression. Our data demonstrated serial MRD monitoring for patients at molecular level could become "digitalized", which was deemed important to guide clinicians in treatment decision for better patient care.

Analytical Performance Evaluation of a Digital Real-Time PCR for Quantifying Major BCR::ABL1 Transcripts.

BACKGROUND: Accurate quantification of the BCR::ABL1 transcripts is essential for measurable residual disease (MRD) monitoring in chronic myeloid leukemia (CML) after tyrosine kinase inhibitor (TKI) treatment. This study evaluated the newly developed digital real-time PCR method, Dr. PCR, as an alternative reverse transcription-PCR (qRT-PCR) for MRD detection. METHODS: The performance of Dr. PCR was assessed using reference and clinical materials. Precision, linearity, and correlation with qRT-PCR were evaluated. MRD levels detected by Dr. PCR were compared with qRT-PCR, and practical advantages were investigated. RESULTS: Dr. PCR detected MRD up to 0.0032%IS (MR4.5) with excellent precision and linearity and showed a strong correlation with qRT-PCR results. Notably, Dr. PCR identified higher levels of MRD in 12.7% (29/229) of patients than qRT-PCR, including six cases of MR4, which is a critical level for TKI discontinuation. Dr. PCR also allowed for sufficient ABL1 copies in all cases, while qRT-PCR necessitated multiple repeat tests in 3.5% (8/229) of cases. CONCLUSION: Our study provides a body of evidence supporting the clinical application of Dr. PCR as a rapid and efficient method for assessing MRD in patients with CML under the current treatment regimen.

Engraftment and Measurable Residual Disease Monitoring after Hematopoietic Stem Cell Transplantation: Comparison of Two Chimerism Test Strategies, Next-Generation Sequencing versus a Combination of Short-Tandem Repeats and Quantitative PCR.

Chimerism testing supports the study of engraftment and measurable residual disease (MRD) in patients after allogeneic hematopoietic stem cell transplant. In chimerism MRD, relapse can be predicted by increasing mixed chimerism (IMC), recipient increase ≥0.1% in peripheral blood, and proliferating recipient cells as a surrogate of tumor activity. Conventionally, the combination of short-tandem repeat (STR) and quantitative PCR (qPCR) was needed to ensure assay sensitivity and accuracy in all chimerism status. We evaluated the use of next-generation sequencing (NGS) as an alternate technique. The median numbers of informative markers in unrelated/related cases were 124/82 (NGS; from 202 single-nucleotide polymorphism), 5/3 (qPCR), and 17/10 (STR). Assay sensitivity was 0.22% (NGS), 0.1% (qPCR), and 1% (STR). NGS batch (4 to 48 samples) required 19.60 to 24.80 hours and 1.52 to 2.42 hours of hands-on time (comparable to STR/qPCR). NGS assay cost/sample was $91 to $151, similar to qPCR ($99) but higher than STR ($27). Using 56 serial DNAs from six post-transplant patients monitored by the qPCR/STR, the correlation with NGS was strong for percentage recipient (y = 1.102x + 0.010; R2 = 0.968) and percentage recipient change (y = 0.892x + 0.041; R2 = 0.945). NGS identified all 17 IMC events detected by qPCR (100% sensitivity). The NGS chimerism provides sufficient sensitivity, accuracy, and economical/logistical feasibility in supporting engraftment and MRD monitoring.

Detection of circulating tumor DNA with ultradeep sequencing of plasma cell-free DNA for monitoring minimal residual disease and early detection of recurrence in early-stage lung cancer.

BACKGROUND: In early-stage non-small cell lung cancer (NSCLC), recurrence is frequently observed. Circulating tumor DNA (ctDNA) has emerged as a noninvasive tool to risk stratify patients for recurrence after curative intent therapy. This study aimed to risk stratify patients with early-stage NSCLC via a personalized, tumor-informed multiplex polymerase chain reaction (mPCR) next-generation sequencing assay. METHODS: This retrospective cohort study included patients with stage I-III NSCLC. Recruited patients received standard-of-care management (surgical resection with or without adjuvant chemotherapy, followed by surveillance). Whole-exome sequencing of NSCLC resected tissue and matched germline DNA was used to design patient-specific mPCR assays (Signatera, Natera, Inc) to track up to 16 single-nucleotide variants in plasma samples. RESULTS: The overall cohort with analyzed plasma samples consisted of 57 patients. Stage distribution was 68% for stage I and 16% each for stages II and III. Presurgery (i.e., at baseline), ctDNA was detected in 15 of 57 patients (26%). ctDNA detection presurgery was significantly associated with shorter recurrence-free survival (RFS; hazard ratio [HR], 3.54; 95% confidence interval [CI], 1.00-12.62; p = .009). In the postsurgery setting, ctDNA was detected in seven patients, of whom 100% experienced radiological recurrence. ctDNA positivity preceded radiological findings by a median lead time of 2.8 months (range, 0-12.9 months). Longitudinally, ctDNA detection at any time point was associated with shorter RFS (HR, 16.1; 95% CI, 1.63-158.9; p < .0001). CONCLUSIONS: ctDNA detection before surgical resection was strongly associated with a high risk of relapse in early-stage NSCLC in a large unique Asian cohort. Prospective studies are needed to assess the clinical utility of ctDNA status in this setting.

Applications of Circulating Tumor DNA in Myelodysplastic Syndromes and Acute Myeloid Leukemia: Promises and Challenges.

The term 'liquid biopsy' has become widely used by clinicians with the development of non-invasive diagnostic and monitoring techniques for malignancies. Liquid biopsy can provide genetic information for early diagnosis, risk stratification, treatment selection and postoperative follow-up. In the era of personalized medicine, liquid biopsy is an important research direction. In recent years, research on circulating tumour DNA (ctDNA) in hematological malignancies has also made great progress. This review provides an overview of the current understanding of circulating tumour DNA in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Additionally, recent advancements in the monitoring of minimal/measurable residual disease (MRD) through ctDNA are discussed.

Early Detection of Molecular Residual Disease and Risk Stratification for Children with Acute Myeloid Leukemia via Circulating Tumor DNA.

PURPOSE: Patient-tailored minimal residual disease (MRD) monitoring based on circulating tumor DNA (ctDNA) sequencing of leukemia-specific mutations enables early detection of relapse for pre-emptive treatment, but its utilization in pediatric acute myelogenous leukemia (AML) is scarce. Thus, we aim to examine the role of ctDNA as a prognostic biomarker in monitoring response to the treatment of pediatric AML. EXPERIMENTAL DESIGN: A prospective longitudinal study with 50 children with AML was launched, and sequential bone marrow (BM) and matched plasma samples were collected. The concordance of mutations by next-generation sequencing-based BM-DNA and ctDNA was evaluated. In addition, progression-free survival (PFS) and overall survival (OS) were estimated. RESULTS: In 195 sample pairs from 50 patients, the concordance of leukemia-specific mutations between ctDNA and BM-DNA was 92.8%. Patients with undetectable ctDNA were linked to improved OS and PFS versus detectable ctDNA in the last sampling (both P < 0.001). Patients who cleared their ctDNA post three cycles of treatment had similar PFS compared with persistently negative ctDNA (P = 0.728). In addition, patients with >3 log reduction but without clearance in ctDNA were associated with an improved PFS as were patients with ctDNA clearance (P = 0.564). CONCLUSIONS: Thus, ctDNA-based MRD monitoring appears to be a promising option to complement the overall assessment of pediatric patients with AML, wherein patients with continuous ctDNA negativity have the option for treatment de-escalation in subsequent therapy. Importantly, patients with >3 log reduction but without clearance in ctDNA may not require an aggressive treatment plan due to improved survival, but this needs further study to delineate.

Combination of minimal residual disease on day 15 and copy number alterations results in BCR-ABL1-negative pediatric B-ALL: A powerful tool for prediction of induction failure.

The current genomic abnormalities provide prognostic value in pediatric Acute Lymphoblastic Leukemia (ALL). Furthermore, Copy Number Alteration (CNA) has recently been used to improve the genetic risk stratification of patients. This study aimed to evaluate CNA profiles in BCR-ABL1-negative pediatric B-ALL patients and correlate the data with Minimal Residual Disease (MRD) results after induction therapy. We examined 82 bone marrow samples from pediatric BCR-ABL1-negative B-ALL using the MLPA method for the most common CNAs, including IKZF1, CDKN2A/B, PAX5, RB1, BTG1, ETV6, EBF1, JAK2, and PAR1 region. Subsequently, patients were followed-up by multiparameter Flow Cytometry for MRD (MFC-MRD) assessment on days 15 and 33 after induction. Data showed that 58.5 % of patients carried at least one gene deletion, whereas 41.7 % of them carried more than one gene deletion simultaneously. The most frequent gene deletions were CDKN2A/B, ETV6, and IKZF1 (30.5 %, 14.6 %, and 14.6 %, respectively), while the PAR1 region showed predominantly duplication (30.5 %). CDKN2A/B and IKZF1 were related to positive MRD results on day 15 (p = 0.003 and p = 0.007, respectively). The simultaneous presence of more than one deletion was significantly associated with high induction failure (p = 0.001). Also, according to the CNA profile criteria, the CNA with poor risk (CNA-PR) profile was statistically associated with older age and positive MRD results on day 15 (p = 0.014 and p = 0.013, respectively). According to our results, the combined use of CNAs with MRD results on day 15 can predict induction failure and be helpful in ameliorating B-ALL risk stratification and treatment approaches.

Droplet digital PCR for sensitive relapse detection in acute myeloid leukaemia patients transplanted by reduced intensity conditioning.

INTRODUCTION: Follow-up after allogeneic transplantation in acute myeloid leukaemia (AML) is guided by measurable residual disease (MRD) testing. Quantitative polymerase chain reaction (qPCR) is the preferred MRD platform but unfortunately, 40%-60% of AML patients have no high-quality qPCR target. This study aimed to improve MRD testing by utilising droplet digital PCR (ddPCR). ddPCR offers patient-specific monitoring but concerns of tracking clonal haematopoiesis rather than malignant cells prompt further validation. METHODS: Retrospectively, we performed MRD testing on blood and bone marrow samples from AML patients transplanted by reduced-intensity conditioning. RESULTS: The applicability of ddPCR was 39/42 (92.9%). Forty-five ddPCR assays were validated with a 0.0089% median sensitivity. qPCR targeting NPM1 mutation detected relapse 46 days before ddPCR (p = .03). ddPCR detected relapse 34.5 days before qPCR targeting WT1 overexpression (p = .03). In non-relapsing patients, zero false positive ddPCR MRD relapses were observed even when monitoring targets associated with clonal haematopoiesis such as DNMT3A, TET2, and ASXL1 mutations. CONCLUSION: These results confirm that qPCR targeting NPM1 mutations or fusion transcripts are superior in MRD testing. In the absence of such targets, ddPCR is a promising alternative demonstrating (a) high applicability, (b) high sensitivity, and (c) zero false positive MRD relapses in non-relapsing patients.

Patient-Specific Measurable Residual Disease Markers Predict Outcome in Patients With Myelodysplastic Syndrome and Related Diseases After Hematopoietic Stem-Cell Transplantation.

PURPOSE: Clinical relapse is the major threat for patients with myelodysplastic syndrome (MDS) undergoing hematopoietic stem-cell transplantation (HSCT). Early detection of measurable residual disease (MRD) would enable preemptive treatment and potentially reduced relapse risk. METHODS: Patients with MDS planned for HSCT were enrolled in a prospective, observational study evaluating the association between MRD and clinical outcome. We collected bone marrow (BM) and peripheral blood samples until relapse, death, or end of study 24 months after HSCT. Patient-specific mutations were identified with targeted next-generation sequencing (NGS) panel and traced using droplet digital polymerase chain reaction (ddPCR). RESULTS: Of 266 included patients, estimated relapse-free survival (RFS) and overall survival (OS) rates 3 years after HSCT were 59% and 64%, respectively. MRD results were available for 221 patients. Relapse was preceded by positive BM MRD in 42/44 relapses with complete MRD data, by a median of 71 (23-283) days. Of 137 patients in continuous complete remission, 93 were consistently MRD-negative, 39 reverted from MRD+ to MRD-, and five were MRD+ at last sampling. Estimated 1 year-RFS after first positive MRD was 49%, 39%, and 30%, using cutoff levels of 0.1%, 0.3%, and 0.5%, respectively. In a multivariate Cox model, MRD (hazard ratio [HR], 7.99), WHO subgroup AML (HR, 4.87), TP53 multi-hit (HR, 2.38), NRAS (HR, 3.55), and acute GVHD grade III-IV (HR, 4.13) were associated with shorter RFS. MRD+ was also independently associated with shorter OS (HR, 2.65). In a subgroup analysis of 100 MRD+ patients, presence of chronic GVHD was associated with longer RFS (HR, 0.32). CONCLUSION: Assessment of individualized MRD using NGS + ddPCR is feasible and can be used for early detection of relapse. Positive MRD is associated with shorter RFS and OS (ClinicalTrials.gov identifier: NCT02872662).

Comparison of Measurable Residual Disease in Pediatric B-Lymphoblastic Leukemia Using Multiparametric Flow Cytometry and Next-Generation Sequencing.

Measurable residual disease (MRD) testing, a standard procedure in B-lymphoblastic leukemia (B-ALL) diagnostics, is assessed using multiparametric flow cytometry (MFC) and next-generation sequencing (NGS) analysis of immunoglobulin gene rearrangements. We evaluated the concordance between eight-color, two-tube MFC-MRD the LymphoTrack NGS-MRD assays using 139 follow-up samples from 54 pediatric patients with B-ALL. We also assessed the effect of hemodilution in MFC-MRD assays. The MRD-concordance rate was 79.9% (N=111), with 25 (18.0%) and 3 (2.2%) samples testing positive only by NGS-MRD (MFC-NGS+MRD) and MFC-MRD (MFC+NGS-MRD), respectively. We found a significant correlation in MRD values from total nucleated cells between the two methods (r=0.736 [0.647-0.806], P<0.001). The median MRD value of MFC-NGS+MRD samples was estimated to be 0.0012% (0.0001%-0.0263%) using the NGS-MRD assays. Notably, 14.3% of MFC-NGS+MRD samples showed NGS-MRD values below the limit of detection in the MFC-MRD assays. The percentages of hematogones detected in MFC-MRD assays significantly differed between the discordant and concordant cases (P<0.001). MFC and NGS-MRD assays showed relatively high concordance and correlation in MRD assessment, whereas the NGS-MRD assay detected MRD more frequently than the MFC-MRD assay in pediatric B-ALL. Evaluating the hematogone percentages can aid in assessing the impact of sample hemodilution.

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

Introduction Acute lymphoblastic leukemia (ALL) is the most common cancer among children. Measurable residual disease (MRD, previously named minimal residual disease) study can guide therapy adjustments or preemptive interventions that might avoid hematological relapse. Methods Clinical decision making and patient outcome were evaluated in 80 real-life childhood ALL patients, according to the results observed in 544 bone marrow samples analyzed with three MRD methods: multiparametric flow cytometry (MFC), fluorescent in-situ hybridization (FISH) on B or T-purified lymphocytes and patient-specific nested reverse transcription polymerase chain reaction (RT-PCR). Results Estimated 5 year overall survival and event-free survival were 94% and 84.1%, respectively. A total of 12 relapses in 7 patients were associated with positive MRD detection with at least one of the three methods: MFC (p < 0.00001), FISH (p < 0.00001) and RT-PCR (p = 0.013). MRD assessment allowed the anticipation of relapse and adapted early interventions with different approaches including chemotherapy intensification, blinatumomab, HSCT and targeted therapy to halt relapse in five patients, although two of them relapsed afterwards. Conclusion MFC, FISH and RT-PCR are complementary methods for MRD monitoring in pediatric ALL. Although, our data clearly show that MDR positive detection is associated with relapse, continuation of standard treatment, intensification or other early interventions were able to halt relapse in patients with different risks and genetic background. More sensitive and specific methods are warranted to enhance this approach. However, whether early treatment of MRD can improve overall survival in patients with childhood ALL needs to be evaluated in adequately controlled clinical trials (AU)

Tumor-Informed Circulating Tumor DNA for Minimal Residual Disease Detection in the Management of Colorectal Cancer.

PURPOSE: Recurrence after curative-intent treatment occurs in 20%-50% of patients with stage II-IV colorectal cancer (CRC), underscoring the need for early detection of minimal residual disease (MRD) using circulating tumor DNA (ctDNA). Here, we examined the pattern of use of a tumor-informed ctDNA assay in CRC MRD monitoring in routine clinical practice at Mayo Clinic, Rochester. METHODS: We conducted a retrospective analysis of health records of patients with CRC who had at least one tumor-informed ctDNA assay from May 2019 through July 1, 2022. Recurrence was defined as radiographic evidence of disease. Descriptive characteristics of the cohort, ctDNA results, and subsequent interventions were recorded. RESULTS: Of the 120 patients included, the median age at diagnosis was 67 years, 46% were female, and 94% were White. At diagnosis, 10 patients had stage I, 23 stage II, 60 stage III, and 25 stage IV disease. Of 476 ctDNA assays performed, 70% were performed in patients who had recurrent disease most commonly to monitor the effectiveness of therapeutic interventions and 16% resulted in a change in clinical decision making. There were 110 recurrences identified in 62 patients, as some patients experienced more than one recurrence over time. Compared with serum carcinoembryonic antigen levels, ctDNA results correlated better with radiologic imaging. CONCLUSION: Routine ctDNA monitoring for MRD detection has been adopted in clinical practice; however, 84% of ctDNA assays performed did not result in a change in clinical management. This suggests the need for further clinical research data to guide routine clinical use of ctDNA MRD testing in CRC.

Clinical Practice Guideline for Blood-based Circulating Tumor DNA Assays.

Circulating tumor DNA (ctDNA) has emerged as a promising tool for various clinical applications, including early diagnosis, therapeutic target identification, treatment response monitoring, prognosis evaluation, and minimal residual disease detection. Consequently, ctDNA assays have been incorporated into clinical practice. In this review, we offer an in-depth exploration of the clinical implementation of ctDNA assays. Notably, we examined existing evidence related to pre-analytical procedures, analytical components in current technologies, and result interpretation and reporting processes. The primary objective of this guidelines is to provide recommendations for the clinical utilization of ctDNA assays.