Minimal Residual Disease Relapse Research Articles

Application and prognostic relevance of CD34 detection in immunophenotyping of pediatric acute B lymphoblastic leukemia.

We aimed to investigate the application of CD34 detection in immunophenotypic discrimination and its prognostic relevance in children with acute B-lymphoblastic leukemia (B-ALL). A retrospective analysis was conducted on clinical follow-up data of 105 children with newly diagnosed B-ALL treated at our hospital from January 2022 to December 2023. Based on the expression of CD34 in the bone marrow, patients were divided into a CD34 positive group (positive cells ≥10%) and a CD34 negative group (positive cells <10%). The study compared the positive rates of common leukemia cell antigens, clinical characteristics, initial treatment responses, and long-term follow-up outcomes between the two groups. Among all 105 B-ALL cases, 87 children (82.9%) had bone marrow CD34 positive cells ≥10%, classified into the CD34 positive group, while the remaining 18 children (17.1%) had bone marrow CD34 positive cells <10%, classified into the CD34 negative group. The CD34 positive group exhibited significantly higher positive rates of CD13 expression, standard-risk B-ALL, and risk stratification than the CD34 negative group. In contrast, the proportions of early pre-B-ALL, E2A-PBX1 fusion gene, and MLL-AF4 fusion gene were significantly lower in the CD34 negative group, with statistically significant differences (p<0.05). No significant differences were found in the positive rates of leukemia cell antigens such as CD10, CD19, CD20, CD22, CD79a, CD13, CD33, and CD38 between the two groups (p>0.05). The occurrence rates of minimal residual disease (MRD) and relapse after induction chemotherapy in the CD34 positive group were significantly lower than those in the CD34 negative group (p<0.05). However, the sensitivity to the first prednisone treatment and bone marrow treatment efficacy on the 19th and 33rd days after chemotherapy showed no significant differences between the groups (p>0.05). A higher positive rate of bone marrow CD34 expression in children with B-ALL is associated with a favorable prognosis. Children with negative CD34 expression are relatively more prone to MRD and tumor relapse after chemotherapy.

Will Survival Improve By Treating Multiple Myeloma Patients at MRD Relapse? the Remnant Study

Background: Although many new treatment options have become available, multiple myeloma (MM) is still considered an incurable disease. The importance of achieving minimal residual disease (MRD) negativity in MM patients has become clearer in recent years. Multiple studies show that bone marrow based MRD assessment is one of the strongest prognostic factors, and deeper responses correlate with more favorable outcomes. The REMNANT study will evaluate if treating at MRD relapse after first line (1.L) treatment prolongs progression-free survival (PFS) and overall survival (OS) in MM patients. Methods: The REMNANT study (RElapse from Mrd Negativity As iNdication for Treatment) is an academic, multicenter, open-label, randomized phase 2/3 study of newly diagnosed (ND) MM patients eligible for autologous stem cell transplant (ASCT). The study has a population-based approach with few exclusion criteria, implying that patients with kidney failure, amyloidosis, plasma cell leukemia and other comorbidities are enrolled. To increase enrollment in part 2, patients who have received 1.L treatment outside the REMNANT study can be enrolled directly if they are &amp;gt;CR/MRD negative. 391 NDMM patients (age 18-75 years) eligible for ASCT will be enrolled in part 1 (phase 2) of the study and receive standard of care Norwegian 1.L treatment; 4 pre-transplant induction and 4 post-transplant consolidation cycles of bortezomib, lenalidomide and dexamethasone (VRd). After induction, patients will undergo tandem or single transplant, depending on toxicity and response to first transplant. All patients receive lenalidomide maintenance. Following 1.L treatment 176 patients achieving MRD negative (Euroflow NGF 10 -5) complete response will be enrolled in part 2 (phase 3) of the study. Patients will be randomized in a 1:1 ratio to receive second line treatment (2.L) at MRD relapse in arm A or at PD in arm B. At loss of MRD negativity in arm A or at PD in arm B, 2.L treatment will be daratumumab, carfilzomib and dexamethasone until PD. The primary endpoint of part 1 (phase 2) of the study is the number of patients who achieve MRD negative (Euroflow NGF 10 -5) complete response 30-45 days post consolidation. Secondary endpoints includes response rates, safety evaluations and patient-reported outcome. The co- primary endpoints in part 2 (phase 3) are PSF and OS from randomization to progressive disease or death on 2.L treatment. We will also compare different methods for measuring MRD: NGF Euroflow, Next Generation Sequencing, mass spectrometry and PET-CT. We want to evaluate how the different methods compare when it comes to sensitivity and outcome (PFS and OS). Results: As of July 18 th 2023, 291 patients are enrolled in part 1 and 97 in part 2 (23 directly enrolled). Baseline characteristics, safety summary and preliminary results can be found in Table 1. The ORR on first line treatment is 95% and 65 of 152 patients (45%) were &amp;gt;CR and MRD negative at the post-consolidation visit. Patients achieving &amp;gt; VGPR but not CR MRD negativity post consolidation are followed for up to 24 months on lenalidomide maintenance, and 11 of 74 patients (15%) in follow-up have converted to &amp;gt;CR/MRD negativity at a median time of seven months (range 2-16). Nine patients have started 2.L treatment in part 2 (phase 3), eight in arm A (MRD guided) and one in arm B (control arm). Median time to loss of MRD negativity among the eight patients in arm A was four months (range 1-6). The most common adverse events were infections, occurring in 24% of patients (any grade). During 1.L treatment, 61 patients have left the study. Seven patients have died, 27 discontinued due to disease progression, 12 patients have withdrawn from the study and seven discontinued due to adverse events. 59% of the patients who progressed during 1. L treatment had high-risk cytogenetics (with gain1q and/or del17p and/or t(4;14)). Conclusion: Standard of care Norwegian first line treatment has an ORR of 95%. The MRD negativity rate among patients who have finished 1.L treatment was 43% (65 of 152). The median time to loss of MRD negativity in arm A (MRD guided) was 4 months.

A Personalized Whole Genome-Informed Assay Targeting Single Mutant in Circulating Tumor DNA Can Identify MRD and Predict Relapse in DLBCL

Introduction: Minimal residual disease (MRD) detected by circulating tumor DNA (ctDNA) has emerged as a promising biomarker in diffuse large B-cell lymphoma (DLBCL). MAESTRO (minor-allele-enriched sequencing through recognition oligonucleotides) was recently developed to aid the detection of low-frequency mutations by enriching for mutant alleles using probes preferentially capturing single-nucleotide variants. We have extended this application - termed MAESTRO-Pool - to analyze personalized MRD variant detection within a cohort-level single assay. We demonstrate high sensitivity to detect MRD using MAESTRO-Pool and the detection of emergent mutations using targeted sequencing of the same samples. Methods: Fifty-nine plasma specimens from 9 patients with relapsed/refractory (R/R) DLBCL treated on a phase II trial (NCT02362997) of post-autologous stem cell transplant (ASCT) pembrolizumab maintenance were tested. Cases were selected based on the availability of genomic DNA from tumor tissue, patient-matched germline DNA, and serial post-ASCT plasma samples (≥ 3 time points). MAESTRO probes were designed to target patient tumor-specific somatic variants using results of baseline tumor-normal whole genome sequencing. Probes were then pooled into an integrated, cohort-level assay (MAESTRO-Pool). Serial samples were compared with an orthogonal, whole-genome, tumor-informed MRD test which does not use mutation enrichment (MRD Tracker; Parsons, HA et al. Clin Cancer Res26, 2556-2564 (2020)) for sensitivity and specificity of variant detection. In addition, sensitivity to detect MRD and predict relapse was compared to that observed with immunoglobulin locus high-throughput sequencing (IgHTS). Additional baits were designed to capture single nucleotide variants (SNVs) previously reported in R/R DLBCL (63 loci in 12 genes), enabling detection of treatment-emergent mutations not identified in baseline tumor specimens. Results: Tumor-normal WGS revealed a median of 433 somatic SNVs per tumor (range 81-1653). The pooled assay comprised 6044 SNV-specific probes. MRD identification was similar for MAESTRO-Pool and MRD Tracker. Among 59 samples, a discrepant MRD call was observed for a single sample where ctDNA was detected at 4 ppm using MRD Tracker, but not detected using MAESTRO-Pool (limit of detection [LoD] 16 ppm). Estimated tumor fractions using MRD Tracker and MAESTRO-Pool were concordant. Even with reduced sequencing requirements of MAESTRO-Pool, we observed a similar median limit of detection (LoD) for MAESTRO-Pool (median 30 ppm, range 1-18,243) and MRD Tracker (median 40 ppm, range 1-4,727 ppm). MAESTRO-Pool identified ctDNA prior to recurrence for all 5 patients who relapsed, including at the earliest available post-ASCT timepoint for 4 of 5 relapsing patients. The time from ctDNA detection to clinical relapse (lead time) was the same or longer for each patient using MAESTRO-Pool (median 178 days, range 69-518) compared to IgHTS (median 44 days, range not detected to 518 days) (p=0.37) (Fig.1a). MAESTRO-POOL was associated with improved sensitivity compared to IgHTS (MAESTRO-Pool sensitivity of 90.5% for samples with matched IgHTS results versus IgHTS sensitivity of 61.9%, p=0.006). Superior sensitivity was primarily driven by MAESTRO-Pool's improved detection of low-frequency (&amp;lt;1000 ppm) mutant alleles. In addition to tracking molecular tumor burden, we identified several de novo mutations in relapsing patients using targeted sequencing of the same samples. Notably, plasma from a patient who progressed at 18.5 months post-ASCT (DL-015) manifested an emergent CREBBP R1446H mutation not detected in the baseline tumor whose allele frequency steadily increased from 0.048% one week after ASCT to 30.533% at relapse (Fig 1b). Conclusion: In this pilot study, MAESTRO-Pool enabled ultrasensitive detection and quantification of MRD with superior sensitivity compared to IgHTS. Complementary targeted sequencing also characterized genetic evolution, including detection of treatment-emergent mutations. Our results support the incorporation of ctDNA testing using MAESTRO-Pool in future prospective trials in DLBCL.

Molecular Monitoring with Tumor DNA and Nivolumab Maintenance: A Pilot Study in Diffuse Large B-Cell Lymphoma

Introduction Molecular minimal residual disease (MRD) has been shown to correlate with disease relapse in patients (pts) with Diffuse Large B cell Lymphoma (DLBCL)[1-4]. However, the clinical impact of detectable MRD (dMRD) prior to clinical relapse is unknown. Checkpoint inhibitor (CPI) therapy has some activity in certain pts with DLBCL, particularly after CAR-T therapy attributed to effects on T cell activity [5-8]. We hypothesized that early intervention with CPI may lower relapse rate in pts with molecular recurrence only. Patients were monitored for detectable MRD (dMRD) by circulating tumor DNA (ctDNA) using the clonoSEQ assay monthly. We conducted a pilot study in high risk pts in remission after most recent line of therapy (LOT) in which maintenance nivolumab (MN) was offered at time of dMRD to assess effect on MRD clearance and relapse rate. Methods Pts &amp;gt;18 years with high-risk DLBCL (ABC-subtype, high grade B cell lymphoma (HGBCL), MYC translocation, relapsed/refractory disease, or Ki67 &amp;gt;90%) who had achieved CR on most recent LOT. Pts had monthly MRD and every 4 month CT or PET/CT and exam for 2 years. If conversion to dMRD without clinical relapse, pts received MN (240 mg IV q2 weeks) until clinical relapse or toxicity for up to 2 years (26 cycles). Pts with overt relapse at time of dMRD were ineligible for MN and taken off trial. The primary endpoint was rate of conversion from +MRD to undetectable MRD (uMRD) in pts receiving . Results 20 pts were screened and 15 pts were enrolled between June 2018 and March 2022. 5 pts had non-GCB subtype, 2 had GCB subtype, and two had unknown cell of origin. 4 had transformed DLBCL (2 from FL, 1 from MZL, and 1 Richter's), 2 pts had HGBCL (one of which was also transformed). Of the 8 pts who enrolled after 1 prior LOT, none had molecular or clinical relapse (Figure). In 7 pts who enrolled after 2+ prior LOT, 3 had dMRD. 2/3 had clinical relapse at same time as dMRD and were taken off study– one at initial enrollment with dMRD at first ctDNA screening and one converting from uMRD to dMRD after 135 days post enrollment. In the single patient who was eligible for MN, dMRD preceded radiographic relapse by 105 days, 410 days after enrollment. The pt went on to receive 2 cycles of MN before clinical progression and was taken off study. This pt failed to achieve conversion of dMRD to uMRD. Conclusions Due to small sample size and lower than expected relapse rates, we were unable to demonstrate conversion of dMRD to uMRD using MN. Of the 3 pts with dMRD, 2 were not eligible for MN due to clinical relapse at same time as dMRD and both died due to lymphoma progression. In the single pt who received MN, this intervention did not achieve uMRD or prevent relapse. However, this pt went on to achieve CR to subsequent CAR-T and remains in prolonged remission despite multiple relapsed/refractory disease. It is unknown if this patient's positive outcome was impacted by the effect of nivolumab on T cells and/or related to slower disease kinetics as this pt had a 3 month period between dMRD and radiographic detection and long duration of response to prior lines. A larger study is needed to adequately assess impact of early intervention MN using MRD kinetics, particularly in patients receiving CAR-T. All pts with dMRD had radiographic relapse within 4 months of molecular relapse. No pts with uMRD by ctDNA had clinical relapse on study during 2 year follow up, confirming uMRD correlates with disease free survival. If a strong negative predictive value is confirmed in a larger study, ctDNA MRD testing may be used to spare pts from imaging or to guide additional work up in pts with inconclusive findings on scans.

Abstract 1853: Microparticle-delivered Cxcl9 prolongs Braf inhibitor efficacy in melanoma

Abstract Patients with BRAF-mutant melanoma show significant responses to combined BRAF and MEK inhibition, but most patients relapse within 2 years. A major reservoir for such drug resistance is minimal residual disease (MRD), which is comprised of drug-tolerant tumor cells laying in a dormant state. Towards exploiting potential therapeutic vulnerabilities of MRD, we established a genetically engineered mouse model of BrafV600E-driven melanoma MRD wherein genetic BrafV600E extinction leads to strong but incomplete tumor regression. Transcriptional time-course analysis of tumors after BrafV600E extinction revealed that after an initial surge of immune activation, tumors later became immunologically "cold" after MRD establishment. Computational analysis identified candidate T-cell recruiting chemokines that may be central players in the process, being strongly upregulated initially and then steeply decreasing as the immune response faded. As a result, we hypothesized that sustaining the chemokine signaling could impair MRD maintenance through increased recruitment of effector T-cells. We show that intratumoral administration of recombinant Cxcl9, either naked or loaded in microparticles, significantly impaired the relapse of MRD in BRAF-inhibited tumors, including several complete pathological responses after the triple combination of microparticle-delivered rCxcl9 with BRAF and MEK-inhibition. Our experiments constitute a proof of concept that chemokine-based microparticle delivery systems are a potential strategy to forestall tumor relapse and thus improve the clinical success of frontline treatment methods. Citation Format: Gabriele Romano, Francesca Paradiso, Peng Li, Pooja Shukla3, Lindsay Barger, Olivia El Naggar, John P. Miller, Roger J. Liang, Timothy L. Helms, Jennifer A. Wargo, Francesca Taraballi, James C. Costello, Lawrence N. Kwong. Microparticle-delivered Cxcl9 prolongs Braf inhibitor efficacy in melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1853.

A Brief Review on Chemoresistance; Targeting Cancer Stem Cells as an Alternative Approach

The acquisition of resistance to traditional chemotherapy and the chemoresistant metastatic relapse of minimal residual disease both play a key role in the treatment failure and poor prognosis of cancer. Understanding how cancer cells overcome chemotherapy-induced cell death is critical to improve patient survival rate. Here, we briefly describe the technical approach directed at obtaining chemoresistant cell lines and we will focus on the main defense mechanisms against common chemotherapy triggers by tumor cells. Such as, the alteration of drug influx/efflux, the enhancement of drug metabolic neutralization, the improvement of DNA-repair mechanisms, the inhibition of apoptosis-related cell death, and the role of p53 and reactive oxygen species (ROS) levels in chemoresistance. Furthermore, we will focus on cancer stem cells (CSCs), the cell population that subsists after chemotherapy, increasing drug resistance by different processes such as epithelial-mesenchymal transition (EMT), an enhanced DNA repair machinery, and the capacity to avoid apoptosis mediated by BCL2 family proteins, such as BCL-XL, and the flexibility of their metabolism. Finally, we will review the latest approaches aimed at decreasing CSCs. Nevertheless, the development of long-term therapies to manage and control CSCs populations within the tumors is still necessary.

Blinatumomab therapy for B cell acute lymphoblastic leukemia accompanied by persistent or relapsed low-level MRD prior to hematopoietic stem cell transplantation in Chinese children: a case series

BackgroundBlinatumomab could be successfully used to reduce minimal residual disease (MRD) prior to hematopoietic stem cell transplantation (HSCT) in pediatric B cell precursor acute lymphoblastic leukemia (BCP-ALL), but sound evidence is lacking in China.Case presentationThis retrospective study assessed the application of blinatumomab in B-ALL accompanied by persistent or relapsed low-level MRD before HSCT from April 2019 to July 2021. Two cases (Cases 1 and 2) initially achieved remission with MRD < 0.01% upon conventional therapy but had MRD relapse with MRD ≥ 0.01% but < 1% during maintenance treatment. Case 3 had no response to routine treatment, with high MRD (9.88% and 1.23% at days 19 and 46, respectively). Nevertheless, all patients had undetectable MRD. Cases 2 and 3 had undetectable fusion gene following blinatumomab therapy. By bone marrow monitoring (bone marrow morphology, bone marrow MRD and fusion gene) post-HSCT, the patients were persistently negative until May 15, 2022. No patient had serious adverse events before or during blinatumomab treatment.ConclusionsBlinatumomab therapy showed a good performance for three pediatric cases with detectable but low MRD before HSCT in China. However, further prospective studies with large sample sizes are still needed for further clarification.

Microparticle-Delivered Cxcl9 Prolongs Braf Inhibitor Efficacy in Melanoma.

Patients with BRAF-mutant melanoma show substantial responses to combined BRAF and MEK inhibition, but most relapse within 2 years. A major reservoir for drug resistance is minimal residual disease (MRD), comprised of drug-tolerant tumor cells laying in a dormant state. Towards exploiting potential therapeutic vulnerabilities of MRD, we established a genetically engineered mouse model of BrafV600E-driven melanoma MRD wherein genetic BrafV600E extinction leads to strong but incomplete tumor regression. Transcriptional time-course analysis after BrafV600E extinction revealed that after an initial surge of immune activation, tumors later became immunologically "cold" after MRD establishment. Computational analysis identified candidate T-cell recruiting chemokines as strongly upregulated initially and steeply decreasing as the immune response faded. Therefore, we hypothesized that sustaining chemokine signaling could impair MRD maintenance through increased recruitment of effector T cells. We found that intratumoral administration of recombinant Cxcl9 (rCxcl9), either naked or loaded in microparticles, significantly impaired MRD relapse in BRAF-inhibited tumors, including several complete pathologic responses after microparticle-delivered rCxcl9 combined with BRAF and MEK inhibition. Our experiments constitute proof of concept that chemokine-based microparticle delivery systems are a potential strategy to forestall tumor relapse and thus improve the clinical success of first-line treatment methods.

Minimal Residual Disease Negativity after Blinatumomab Is Predictive of Survival in B-Cell Acute Lymphoblastic Leukemia: Data from a Real-Life Study

Introduction The novel pediatric-like and TKI-based induction regimens induce up to 90 % of complete hematologic response in, respectively, Ph'-negative and Ph'-positive B-Cell Acute Lymphoblastic Leukemia (B-ALL). Minimal residual disease (MRD) strongly correlates with relapse and clearance of MRD is the goal of treatment. Blinatumomab is a bispecific T-cell engager that redirects T-Cells to kill CD19+ cells. Data from clinical trials show that the MRD-positive patients responding to Blinatumomab achieve a better survival than the non-responsive. This retrospective study from real-life demonstrates a superior outcome for MRD-responsive patients to blinatumomab over non-responsive patients. Patients and methods Data from adults treated with blinatumomab in six centers were analyzed to identify factors correlated to survival. Each cycle of blinatumomab was administered in 4 weeks at 15 mg/m2/day by continuous infusion followed by a 2-week interval. Intrathecal prophylaxis with ARA-C, Methotrexate and Dexamethasone was performed between cycles. Twenty-nine (87 %) patients received levetiracetam for seizure-prophylaxis. MRD was measured after each cycle by RT-qPCR with a sensitivity of 10-4 for clonal IgH and for BCR-ABL. As MRD response was considered clonal IgH or BCR-ABL < 10-4. Relapse-free survival (RFS) and overall survival (OS) were estimated by the Kaplan-Meier analysis and compared by the log-rank across the sub-groups using 95 % confidence intervals. The significant variables were compared in multivariate analysis by the log-logistic regression model. Toxicity was graded according to CTCAEs v.4 scale. Results From January 2016 to February 2021 34 B-ALL patients received Blinatumomab. The median age was 37 (18-72). Male to female ratio was 14/20. B-ALL was Ph'+ in 9 and Ph'- in 25 patients, respectively. Indications to blinatumomab were, respectively, relapsed/refractory B-ALL in 19 and MRD-positive in 15 patients. SNC disease was negative before blinatumomab in all patients. Blinatumomab was administered, respectively, as 2nd line in 26 and as > 2nd line of therapy in 8 patients. Overall, 24 patients received hematopoietic transplantation (HCT): 10 before and 14 after blinatumomab, respectively. The cycles of blinatumomab were 1, 2, 3 and 4, respectively, in 10, 13, 5, and 5 patients. The response to blinatumomab was, respectively, complete remission without MRD in 17 (50 %), complete remission with MRD in 8 (23 %), refractory in 4 (12 %) and extramedullary progression in 2 (6 %) patients. Three patients (9 %) had to suspend treatment in 1st cycle because of grade III-IV neuro-toxicity. The response was obtained after 1 and 2 cycles in 18 (72 %) and 7 patients (28 %), respectively. Among the MRD-responsive, MRD-negativity was obtained after 1 and 2 cycles in 16 (93 %) and 1 (7 %) patient, respectively. At a median follow-up of 16 months (1-47) 15 patients (44 %) had relapsed, 15 (44 %) were alive and in complete remission and 4 (12 %) died of transplant-related mortality. The median RFS was 12.5 months (1-39). The median OS was 15.5 months (1-46). The median RFS was 21 vs 4.4 months among MRD-responsive and non-responsive patients, respectively (p = .0004). The median OS was 27 vs 8.7 months among MRD-responsive and non-responsive patients, respectively (p = .008). Apart from MRD-response, the other variables significant for RFS were: blinatumomab as ≤ 2nd line (p = .0008), blinatumomab administered pre-HCT (p = .002) and MRD as an indication to treatment (p = .001). Apart from MRD-response, the other variable significant for OS was MRD as an indication (p = .01). By multivariate analysis only the MRD-response resulted significant for RFS (p = .0009) and OS (p = .02). MRD-response resulted significantly for RFS and OS also by censoring at HCT (p < .0001 and .005, respectively) [Figure 1]. Clinically significant toxicity was: grade II cytokine-release syndrome in 2 patients, grade III and IV neuro-toxicity in 2 and 1 patient, respectively. Overall, the percentage of patients experiencing grade III-IV neuro-toxicity, which occurred in 1st cycle, was 9 %. Conclusion This retrospective study in adult B-ALL Ph'- and Ph'+ patients, confirms the ability of blinatumomab to reach the MRD-negativity in a substantial proportion of patients. MRD-responsive gain a significant survival advantage over non-responsive patients. This advantage was observed both for transplanted and non-transplanted patients. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Why is it Important to Identify Residual Cells in Leukaemia Patients after Treatment? A Review Article

Introduction: Most children diagnosed with acute lymphoblastic leukemia are cured and are not at risk of relapse. However, 20% of children are at a high risk of experiencing relapse later on in their lives. In order to detect risk and obtain prognostic information, the quantification of minimal residual disease (MRD) can be utilized. Detection of MRD can lead to efficient identification of relapse risk. However, there is limited understanding of the association between MRD and long-term outcomes after treatment in children. Therefore, this systematic review will examine existing literature to determine the strength of association between MRD negativity and relapse risk in children and its importance in the prediction of relapse. Methods: A systematic review of 5 articles centered around ALL in children was analyzed to examine the strength of association between MRD negativity and clinical outcomes of event-free survival (EFS) and overall survival (OS) following the PRISMA guideline. The literature search was done through databases such as NCBI, PubMed, and other childhood oncology databases. The inclusion criteria included peer-reviewed clinical studies that focus on ALL relapse risk and MRD detection. Additionally, reviews, abstracts, and studies with inadequate sample sizes or correlations were excluded. Data were extracted and organized based on criteria of MRD negativity, MRD detection type, and relapse risk level. The data collected from all studies were analyzed through a meta-analysis. The five publications discussed in this article were a total of 11,265 participants. Results: The results portion of your abstract should concisely describe a summary of the main findings. A positive correlation was determined between EFS and OS hazard ratios and MRD detection. Discussion: The analysis of the five publications demonstrated that MRD is an important marker and a strong predictor of relapse in children who are diagnosed with ALL. Conclusion: MRD detection can be proposed as a method of predicting a high risk of relapse in children with ALL. In essence, this literature review has the potential to identify the clinical and therapeutic significance of MRD testing which can be utilized to predict and prevent relapse of ALL in children.

Dynamic monitoring circulating tumor DNA in plasma samples by PEAC technology for patients with early-stage non–small cell lung cancer after surgery.

8547 Background: Local recurrence or distant metastasis after surgery is not rare for early-stage Non-Small Cell Lung Cancer (NSCLC) patients. Present clinicopathological parameters, such as TNM stages and pathological subtype, are limited effective, as Positive Predictive Value (PPV) is low while Negative Predictive Value (NPV) is high. In recent years, circulating tumor DNA (ctDNA) has emerged as a noninvasive method for early diagnosis, prognostic stratification, disease surveillance, and treatment response evaluation. We assessed whether circulating tumor DNA (ctDNA) detected by PEAC technology could be a biomarker for minimal residual disease (MRD) and prediction of postoperative relapse in early-stage NSCLC. Methods: We enrolled 132 NSCLC patients with EGFR, KRAS, NRAS, BRAF and PIK3CA mutations, and obtained plasma samples at five perioperative time points (before surgery, 3-7 days, 6-months, 12-months and 18-months after surgery). Using PEAC technology, somatic mutations in plasma samples were identified and utilized for ctDNA-based MRD analysis. Clinical follow-ups were collected. Results: Our data showed that 32.0% (8 of 25) of patients with positive preoperative ctDNA experienced postoperative relapse, compared with 7.2% (6 of 83) in ctDNA negative patients, demonstrating that preoperative ctDNA status is an effective prognosis factor for NSCLC. In time point of 3-7 days after surgery, plasma samples were obtained from 47 patients, of which 33.3% (2 of 6) with positive ctDNA experienced postoperative relapse, while only 4.9% (2 of 41) in ctDNA negative patients. The result suggests that ctDNA positive in plasma samples of 3-7 days after surgery might be a strong biomarker for MRD detection and relapse prediction. For ctDNA surveillance, plasma samples from 6-months, 12-months and 18-months after surgery were collected and detected. At any one of the three tests ctDNA is positive, 20.0% (8 of 40) patients experienced clinical relapse, while 5.1% (3 of 59) patients with ctDNA negative status at all times relapse. A total of 14 recurrence events had occurred, ctDNA positivity precedes radiological recurrence by a median of 150.5 days (90.5 – 182, P = 0.006). Conclusions: Perioperative ctDNA analysis using PEAC technology is effective in early detection of MRD and relapse prediction, and hence could benefit NSCLC patient management in clinical settings. Clinical trial information: NCT03465241.

First-in-human phase 1 trial of ELI-002 immunotherapy as treatment for subjects with Kirsten rat sarcoma (KRAS)-mutated pancreatic ductal adenocarcinoma and other solid tumors.

TPS2701 Background: Mutations in KRAS and NRAS occur in one quarter of human solid tumors. The G12D allele is the most commonly occurring variant in pancreatic, colorectal, non-small cell lung, ovarian, biliary and gallbladder cancers. ELI-002 2P is an immunotherapeutic comprised of a lymph-node targeted amphiphile (AMP)-modified G12D and G12R mutant KRAS peptides together with an AMP-modified CpG oligonucleotide adjuvant. In preclinical models, ELI-002 demonstrated increased cytotoxic KRAS-specific T cells compared to non-lymph node targeted controls using the same peptide and adjuvant. Clinical evaluation of adoptively transferred KRAS-specific T cells demonstrated objective antitumor activity (Tran 2016). Circulating tumor (ctDNA) methodology permits identification of patients with minimal residual disease (MRD) following locoregional treatment. In MRD setting, immunotherapy is anticipated to succeed as the ratio of effector T cells to target tumor cells is maximized prior to bulk visible disease. The AMPLIFY-201 study (NCT04853017) is evaluating ELI-002 in patients with KRAS mutated solid tumors with MRD. Methods: AMPLIFY-201 is an open-label, dose-escalation and expansion phase I, first in human, trial evaluating ELI-002 2P in patients with KRAS mutated tumors with MRD following standard of care therapy. The initial phase I cohort enrolls patients with colorectal and pancreatic cancer to receive multiple doses of AMP-peptides 70mcg each (1.4 mg total) admixed with AMP-CpG 0.1 mg, administered once every two weeks. Subsequent phase I cohorts will enroll patients with RAS-mutated pancreatic, colorectal, non-small cell lung, ovarian, bile duct or gallbladder cancer, who will receive a fixed dose of AMP-peptides 70 mcg each, together with escalating doses of AMP-CpG. Safety and efficacy will be summarized with descriptive statistics. The maximum tolerated dose (if any) and the recommended phase II dose (RP2D) will be determined with the dose-response activity of ELI-002 2P in eliciting functional KRAS-specific T cells. Preliminary antitumor activity will be characterized using changes from baseline in ctDNA, serum biomarkers appropriate for tumor type, and progression free survival time. Eligibility includes patients who have received standard of care locoregional treatment according to NCCN guidelines and whom have MRD persistence or relapse (ctDNA positive). Patients with colon and pancreas cancer with Stage IV oligometastatic disease (&lt; 3 lesions in one organ) rendered surgically free of disease and with MRD, are also eligible. The dose escalation portion of the study is currently enrolling. Clinical trial information: NCT04853017.

Metabolomic Profiling Improves Prediction of Early Disease Response and Relapse in Pediatric Acute Lymphoblastic Leukemia

Introduction: Although outcomes for pediatric acute lymphoblastic leukemia (ALL) have improved dramatically, five-year survival remains dismal for those cases which relapse. Initial response to therapy, measured by minimal residual disease (MRD) at end-induction, is the most important predictor of outcome. However, approximately half of relapses occur in MRD-negative patients. We hypothesized that global metabolomic profiling of diagnostic bone marrow plasma could improve prediction of MRD positivity and relapse when combined with clinical features, while also providing insights into the biologic features of these chemotherapy-resistant groups.Methods: The study population (n=100) included children age 0-18 years with newly diagnosed ALL treated at Texas Children's Cancer Center. The cohort included 39 cases with MRD ≥ 0.01% at end-induction. Ninety-four children were followed for at least 3 years from diagnosis, of whom 23 relapsed. Diagnostic bone marrow plasma specimens were obtained with informed consent and subjected to metabolomic profiling via UPLC-MS/MS by Metabolon. Following compound identification and correction for batch effects, each compound was scaled such that the median concentration was one and missing values were imputed with the minimum detected concentration.Analysis was limited to 712 named compounds that were detected in at least two samples. We used Welch's two-sample t-test to compute p-values comparing mean concentrations in MRD positive vs. negative and relapsed vs. non-relapsed plasma and chi-squared test to assess differences in the frequency of detection. We then generated volcano plots to visualize the significance of each metabolite.Compounds demonstrating significance at the p < 0.001 level were then evaluated in logistic regression models for MRD and relapse, and the best predictors were obtained by backward elimination. Finally, we assessed the performance of models to predict MRD and relapse using (1) clinical features alone (immunophenotype, cytogenetics and National Cancer Institute risk category, plus end-induction MRD when predicting relapse); (2) metabolomic data alone; and (3) clinical features + metabolomic data. DeLong's test for correlated receiver operating characteristics curves was used to compare model performance.Results: In the assessment of individual metabolites, a higher concentration of pyruvate was associated with an increased odds ratio (OR) of MRD positivity (p = 0.005). Conversely, a significantly reduced OR for MRD was identified for arachidonylglycerol (p = 0.01). Reduced ORs for relapse were identified for increasing concentrations of two compounds involved in amino acid metabolism: picolinic acid and N-carboxyethylphenylalanine (p = 0.04 and 0.02, respectively), as well as for the vitamin E derivative gamma-CEHC (p = 0.03). Several glycerophospholipids demonstrated inverse associations with MRD positivity and relapse.Metabolomic profiling significantly improved prediction of both MRD and relapse as compared to clinical features alone (p = 0.001 and p = 0.03 respectively; Figure 1). Incorporating metabolomic data gave an absolute improvement in sensitivity of 8% for MRD and 19% for relapse.Conclusions: We demonstrate that global metabolomic profiling improves sensitivity and specificity when predicting risk of MRD positivity and relapse in ALL. Differences in pyruvate and lipid concentrations suggest metabolic changes associated with chemoresistance or disease recurrence which may be therapeutically targetable. If validated, these metabolomic biomarkers may improve clinical risk prediction and further our understanding of disease biology. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Bone Marrow Infiltrating T-Cell Signatures Following Allo-HCT for Adult Acute Lymphoblastic Leukaemia Differentiate between Patients in Continuous CR and Those with Persistent Minimal Residual Disease or Relapse

Allogeneic stem cell transplantation (allo-HCT) has a proven survival benefit in adult acute lymphoblastic leukaemia (ALL) and remains the most commonly applied immunotherapy. The mechanism of graft-versus-leukaemia (GVL) in allo-HCT relies upon donor T cell immunity. After contributing to initial control of ALL, allo-reactive anti-tumour T cells may either persist, thus providing continuing immune surveillance, or undergo deletion/loss of function as a result of both extrinsic regulation and/or exhaustion. Therefore, there is a clear need to identify and track T cells with potential anti-ALL reactivity. UKALL14 (ISRCTN66541317) is an ongoing clinical trial for adults with de novo ALL in the UK in which all patients over 40 years are regarded as ‘high risk’ and are assigned to reduced intensity-conditioned allo-HCT. Minimal residual disease (MRD) monitoring - by immunoglobulin heavy chain/ T cell receptor quantification - of bone marrow and peripheral blood multilineage chimerism are assessed at regular intervals for 2 years post allo-HCT.We hypothesised that it would be possible to differentiate bone marrow infiltrating T-cell (BiL-T) signatures in patients in complete molecular remission versus those with MRD or frank clinical relapse. We have evaluated the feasibility of performing gene expression profiling on BiL-T cells from cryopreserved bone marrow samples of patients following allo-HCT and correlated this information with clinical outcome data.BiL-T were flow-sorted using the BD FACSAria ™ Fusion into CD3+,TCRab+, CD4+ and CD3+,TCRab+, CD8+. After extraction of total mRNA, samples with an RNA integrity index (RIN) >7 were subjected to RNA sequencing using the Illumina Hiseq. Data were analysed using differential expression gene analysis (DeSeq 2) and gene set enrichment analysis (GSEA). The Human Immunology V2 panel on the NanoString nCounter® SPRINT Profiler was used for gene expression profiling of samples with adequate RNA but a RIN <7. Gene expression data was correlated with molecular MRD data and other clinical parameters, including T cell chimerism where available.Both CD4+ and CD8+ subsets of BiL-T were successfully sorted from all 15 cryopreserved samples. DeSeq2 and GSEA of the RNAseq data was performed for CD4+TCRab+ BiL (n=5; 3 MRD- and 2 MRD+/relapse) (Figure 1) and CD8+TCRab+ (n=6; 4 MRD- and 2 MRD+/relapse). Despite the modest number of samples in this feasibility study, CD4+ T cells from patients with relapsing or MRD+ ALL showed significantly increased expression of genes associated with terminal differentiation (e.g. LAG3, GZMK); by contrast, there was lower expression of genes associated with memory differentiation and proliferative fitness (e.g. MYC, CCR7), a finding linked to increased pathway enrichment for PD-1 and telomere maintenance. CD8+ T cells from patients with relapsing or MRD+ ALL also demonstrated a terminally differentiated signature (e.g. increased expression of KLRC1 encoding NKG2A and lower expression of CCR7). GSEA showed enrichment for pathways linked to oxidative phosphorylation and interaction with non-haematopoetic stroma). We also analysed n=9 CD8+TCRab+ samples (n=4 MRD- and n=5 MRD+ or relapse) by Nanostring. These groups could also be segregated on the basis of genes representing pathways related to T cell survival, death receptor signalling and TCR signalling; in each case, CD8+ T cells from MRD+ or relapsing patients were characterised by a hypo-functional and apoptosis-prone signature.Our data show features suggestive of T cell exhaustion and altered metabolomes in patients with residual ALL post-allo-HCT, whether they are MRD+ or in frank clinical relapse; these features were not present in patients in continuous remission. To further test the hypothesis that T cell dysfunction significantly compromises GVL efficacy, we intend to perform transcriptional profiling of BiL-T in a wider cohort of UKALL14 patients who underwent allo-HCT. Since clinical strategies for reversal of T cell exhaustion including donor lymphocyte infusion (DLI) and potential PD-1 blockade already exist, we hope the impact of this project will be to determine precisely when and in whom to use these strategies during therapy for adult ALL. We expect that our findings will have relevance to the wider field of immunotherapy for ALL including blinatumomab and CAR-T approaches. [Display omitted] DisclosuresFielding:Baxalta: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees.

Ibrutinib (Ibr) Plus Venetoclax (Ven) for First-Line Treatment of Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Lymphoma (SLL): 1-Year Disease-Free Survival (DFS) Results From the MRD Cohort of the Phase 2 CAPTIVATE Study

Ibrutinib (Ibr) Plus Venetoclax (Ven) for First-Line Treatment of Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Lymphoma (SLL): 1-Year Disease-Free Survival (DFS) Results From the MRD Cohort of the Phase 2 CAPTIVATE Study

Relapse from MRD Negativity As Indication for Treatment in Multiple Myeloma - the Remnant Study

Background: Early intervention can reduce the rate of progression and improve overall survival (OS) in smouldering multiple myeloma (SMM) patients (pts) (1, 2). The most powerful predictor of prognosis in active MM is whether pts achieve minimal residual disease (MRD) negativity in bone marrow with treatment (3), however treating MRD relapse has not been evaluated in a randomized fashion. The REMNANT study will evaluate whether treating MRD relapse after first line (1.L) treatment prolongs progression free survival (PFS) and OS for MM pts versus treating relapse after 1.L. treatment at progressive disease (PD) (4). To establish a homogenous group of MRD negative pts after 1.L treatment including autologous stem cell transplantation (ASCT), pts are enrolled at diagnosis and treated with Norwegian standard of care (SOC) 1.L treatment. MRD negative pts will move on to the randomized part. Methods: The REMNANT study is an academic, multicenter, open-label, randomized phase II/III study of NDMM pts eligible for ASCT (see Figure 1). 391 pts across Norway will be included in the phase II part of the study and receive SOC 1.L treatment according to Norwegian national guidelines; VRd (V: 1,3 mg/m2 SC Days 1, 4, 8, 11; R: 25 mg PO Days 1-14; d: 20 mg PO Days 1, 2, 4, 5, 8, 9, 11, 12) for 4 pre-transplant induction and 4 post-transplant consolidation cycles (all 21-d cycles). After induction pts will undergo tandem or single ASCT, depending on toxicity and response to first ASCT. The primary endpoint of the phase 2 part of the study is the number of pts who achieve MRD negative (Euroflow NGF 10 -5) complete response (CR) 30-45 days post consolidation. Safety evaluations and pts-reported outcome assessment will be measured. Pts (176) achieving MRD negative CR will be randomly assigned in a 1:1 ratio to receive 2.L treatment at MRD reappearance (arm A) or at progressive disease (PD) as defined by the IMWG criteria (4) (arm B). Randomization will be stratified by R-ISS stage at diagnosis and single vs tandem ASCT. Pts in arm A will be followed with MRD assessment every 4 month and start 2.L treatment at loss of MRD negative CR. Pts in arm B will be followed up by standard criteria and start 2.L treatment at PD. Both arms will receive the same 2.L treatment; KdD (all 28-d cycles) (K: 70mg/m2 iv Days 1,8,15 d: 40 mg Days 1, 8, 15, 22 D: 1800 mg SC Days 1, 8, 15 during C 1-2, Days 1, 8 during cycle 3-6, Day 1 from cycle 7,). 2.L treatment will continue until disease progression, unacceptable AEs or patient withdrawal. In arm A MRD Euroflow will be assessed after 6 and 18 months of 2L therapy. In arm B MRD Euroflow will be assessed if &amp;gt;CR is achieved but not before 6 months of 2 L therapy, and again after 12 consecutive months. The co-primary endpoint is progression and death by any cause (PFS) and death by any cause alone (OS). Secondary endpoints includes TTNT and the proportion pf pts who achieve MRD negative CR during 2.L treatment in arm A and arm B, safety evaluations and pts-reported outcome. The trial is approved and will start enrollment Q3 2020. 1. Mateos MV, Hernandez MT, Giraldo P, de la Rubia J, de Arriba F, Corral LL, et al. Lenalidomide plus dexamethasone versus observation in patients with high-risk smouldering multiple myeloma (QuiRedex): long-term follow-up of a randomised, controlled, phase 3 trial. Lancet Oncol. 2016;17(8):1127-36. 2. Lonial S, Jacobus S, Fonseca R, Weiss M, Kumar S, Orlowski RZ, et al. Randomized trial of lenalidomide versus observation in smoldering multiple myeloma. 2020;38(11):1126-37. 3. Munshi NC, Avet-Loiseau H, Rawstron AC, Owen RG, Child JA, Thakurta A, et al. Association of Minimal Residual Disease With Superior Survival Outcomes in Patients With Multiple Myeloma: A Meta-analysis. JAMA Oncol. 2017;3(1):28-35.5. 4. Kumar S, Paiva B, Anderson KC, Durie B, Landgren O, Moreau P, et al. International Myeloma Working Group consensus criteria for response and minimal residual disease assessment in multiple myeloma. Lancet Oncol. 2016;17(8):e328-e46. Disclosures Schjesvold: Amgen, Celgene, Janssen, MSD, Novartis, Oncopeptides, Sanofi, SkyliteDX, Takeda: Honoraria; Celgene, Amgen, Janssen, Oncopeptides: Research Funding; Amgen, Celgene, Janssen, MSD, Novartis, Oncopeptides, Sanofi, Takeda: Consultancy. OffLabel Disclosure: Carfilzomib-dexamethason-daratumumab (KdD) as second line treatment

The Next Step for MRD in Myeloma? Treating MRD Relapse after First Line Treatment in the REMNANT Study

The treatment approach for multiple myeloma (MM) has changed in recent years. After the approval of maintenance treatment after stem cell transplant in younger patients, the paradigm of continuous treatment is now prevailing in all clinical situations of myeloma. However, the best time to initiate relapse treatment is still unclear. With increased frequency of minimal residual disease (MRD) negativity, and the established clinical benefit of this finding, one of the large clinical questions in myeloma is how to approach MRD re-appearance. In this paper, we go through the MRD technology, existing and possible uses of MRD in the clinic, and data for early treatment before we introduce the design of the ongoing REMNANT study; a randomized study with early treatment of MRD relapse after first line treatment.

Blinatumomab and Venetoclax for Minimal Residual Disease Relapse in Acute Lymphoblastic Leukemia

Introduction: The 5-year relative survival in patients aged 15-24 years old is around 57% (Blood 2019; 134: 407-410), with a median survival after relapse of 10 months. No uniform consensus about rescue treatment is available, but those who achieve a complete remission can undergo to an allogeneic transplant if feasible. The use of intense rescue chemotherapy is associated with systemic toxicities and risk of serious infections that can delay an allogeneic transplant. Objective: We describe the combination of two ALL targeted therapies, combining bispecific T-cell engager (BiTE) against CD 19 (Blinatumomab) and selective inhibitor of the B-cell lymphoma 2 (Bcl-2) regulator protein, an antiapoptotic protein (Venetoclax). This combination was developed based in their mechanism of action that offers synergetic effects against ALL cells and the reports of ongoing clinical trials using Venetoclax combinations for ALL, but no with Blinatumomab. Patients and methods: Patients with B cell precursors ALL in minimal residual disease relapse by flow cytometry. Rescue treatment with Blinatumomab and Venetoclax before allogeneic transplant. Results: Two patients treated with LAFAMI-LLA-2002 Protocol (Blood 2009; 114: 4104 and Hematologia 2016; 17: 5137), adapted to young adults with high dose methotrexate at 5 gr/m2 every four months in the maintenance phase, had MDR positivity by FC in the surveillance phase, with normal CBC. One male with 22 years old at the time of relapse, after 60 months of surveillance with 1.9 % of malignant lymphoblasts. One female with 21 years old at the time of relapse, after 25 months of surveillance with 0.2 % of malignant lymphoblasts. Both relapses were confirmed with an additional MRD one week after. Extension studies were performed, including PET-CT, to determinate other affected sites and were negative. Treatment administrated was Blinatumomab at 9 mcg/day continuous IV infusion on days 1-7 and 28 mcg/day on days 8-14 with Venetoclax in a ramp-up phase for 5 weeks. Both patients were in negative MRD after the complete Blinatumomab and continue with Venetoclax while a donor was available. No side effects were observed during and after the treatment. Both patients had a compatible sibling and underwent for allogeneic transplant. At the moment of this report the patients have 11 months and 18 months after transplant with EMR negative and complete donor cells from the bone marrow, with no secondary effects. Conclusion: This is a novel combination with no reports of its use before our communication. Targeted therapies in low leukemic burden is a feasible treatment with no side effects and rapid control of the relapse, allowing the patients to reach an allogeneic transplant as soon as possible avoiding substantial toxicity and risk of infections. No infusion related reaction or cytokine release syndrome were observed due low leukemic burden. More patients need to be included to this combination to demonstrate reproducibility, optimizing time and costs. OffLabel Disclosure: Blinatumomab and Venetoclax combination for acute lymphoblastic leukemia relapse

Homoharringtonine potentiates the antileukemic activity of arsenic trioxide against acute myeloid leukemia cells

Relapse of minimal residual disease (MRD) is a major problem after conventional chemotherapy in patients with acute myeloid leukemia (AML). The bone marrow stroma can protect AML cells from insults of chemotherapy, partly contributing to AML relapse. Arsenic trioxide (ATO) is the main component of arsenical traditional Chinese medicines and has been widely used for the treatment of hematologic malignancies particularly acute promyelocytic leukemia over the past three decades. ATO acts through a direct arsenic binding to cysteine residues in zinc fingers located in promyelocytic leukemia protein (PML), thus killing the leukemia stem cells (LSCs). Our prior study has demonstrated that adhesion to stroma cells could render AML cells resistant to ATO but the detailed mechanism remains to be explored. Here, we report that the adhesion-induced resistance to ATO is related to the up-regulation of myeloid cell leukemia-1 (Mcl-1). Homoharringtonine (HHT) can potentiate the anti-leukemia effects of ATO on adhered AML cells by suppressing Mcl-1 through glycogen synthase kinase-3β (GSK3β). Furthermore, a potentiating effect of HHT on ATO was also observed in primary AML cells and AML xenografted tumors. Thus, these data indicate that HHT could enhance ATO anti-leukemia activity both in vitro and in vivo.

Quantitative monitoring of minimal residual disease in childhood acute lymphoblastic leukemia using TEL-AML1 fusion transcript as a marker.

ABSTRACTImportanceBy demonstrating with TEL‐AML1, this study indicated that mRNAs transcribed from fusion genes are ideal targets for minimal residual disease (MRD) monitoring in childhood acute lymphoblastic leukemia, and that different thresholds are needed to apply them into the risk stratification.Objective TEL‐AML1 expression was measured at three time points to 1) determine cut‐off values for predicting acute lymphoblastic leukemia (ALL) relapse; 2) investigate the prognostic value of this method and how well the results at these time points correlated; 3) determine the correlation between MRD levels assessed using this marker and that determined by immunoglobulin/T‐cell receptor (Ig/TCR) rearrangement detection.Methods TEL‐ AML1 expression in 62 children with ALL was quantitated by real‐time quantitative PCR at day 15, day 33, and month 3. The relationship between patient outcome and TEL‐AML1 level was analyzed at each time point. The correlation between the MRD levels determined by TEL‐AML1 or Ig/TCR rearrangements was also analyzed.ResultsFor day 33, 6.68 TEL‐AML1 copies/104 ABL copies was determined to be the best cut‐off value. Higher levels were correlated with relapse (P = 0.001). For day 15 and month 3, the best cut‐off values were 336.5 and 0.85 copies/104 ABL copies respectively; patients with higher expression levels had lower RFSs (day 15: P = 0.027; month 3: P = 0.023). For days 15 and 33, MRD levels assessed using TEL‐AML1 or Ig/TCR rearrangements were strongly correlated [Spearman rank correlation coefficient (ρ) = 0.729 (day 15), 0.719 (day 33); P < 0.001 (both)], and both methods were equally effective at predicting relapse. At month 3, there was moderate correlation between the results derived from the two markers (ρ = 0.418, P = 0.003); however, receiver operating characteristic curve analysis showed that TEL‐AML1 was a better prognostic marker.Interpretation TEL‐AML1 is an effective marker for MRD assessment and relapse prediction in children with ALL.