Molecular Measurable Residual Disease Research Articles

Correlation between a 10-color flow cytometric measurable residual disease (MRD) analysis and molecular MRD in adult B-acute lymphoblastic leukemia.

Measurable residual disease (MRD) monitoring in acute lymphoblastic leukemia (ALL) is an important predictive factor for patient outcome and treatment intensification. Molecular monitoring, particularly with quantitative polymerase chain reaction (qPCR) to measure immunoglobin heavy or kappa chain (Ig) or T-cell receptor (TCR) gene rearrangements, offers high sensitivity but accessibility is limited by expertise, cost, and turnaround time. Flow cytometric assays are cheaper and more widely available, and sensitivity is improved with multi-parameter flow cytometry at eight or more colors. We developed a 10-color single tube flow cytometry assay. Samples were subject to bulk ammonium chloride lysis to maximize cell yields with a target of 1 × 106 events. Once normal maturation patterns were established, patient samples were analyzed in parallel to standard molecular monitoring. Flow cytometry was performed on 114 samples. An informative immunophenotype was identifiable in all 22 patients who had a diagnostic sample. MRD analysis was performed on 87 samples. The median lower limits of detection and quantification were 0.004% (range 0.0005%-0.028%) and 0.01% (range 0.001%-0.07%) respectively. Sixty-five samples had concurrent molecular MRD testing, with good correlation (r=0.83, p < 0.001). Results were concordant in 52 samples, and discordant in 13 samples, including one case where impending relapse was detected by flow cytometry but not Ig/TCR qPCR. Our 10-color flow cytometric MRD assay provided adequate sensitivity and good correlation with molecular assays. This technique offers rapid and affordable testing in B-ALL patients, including cases where a suitable molecular assay cannot be developed or has reduced sensitivity.

A Prospective Phase 2 Study of Venetoclax and Low Dose Ara-C (VALDAC) to Target Rising Molecular Measurable Residual Disease and Early Relapse in Acute Myeloid Leukemia

A Prospective Phase 2 Study of Venetoclax and Low Dose Ara-C (VALDAC) to Target Rising Molecular Measurable Residual Disease and Early Relapse in Acute Myeloid Leukemia

Diagnostic Utility of Multimodal Genomic Profiling for Molecular Classification and MRD Assessment in Adult B-Cell Acute Lymphoblastic Leukemia

Genomic markers define molecular subtypes and measurable residual disease (MRD) targets in B-cell acute lymphoblastic leukemia/lymphoma (B-ALL) and are essential determinants of treatment. Current diagnostic approaches typically involve serial multi-step testing utilizing conventional cytogenetics (CC)/FISH and molecular genetic (RT-qPCR, MLPA, clonality PCR, NGS panel) techniques which are time and sample consuming and ultimately may not adequately identify genomically complex B-ALL subtypes. In contrast, single-step comprehensive genomic profiling by whole genome and whole transcriptome sequencing (WGS/WTS) may be more efficient for the molecular classification of established and newly described entities which are of increasing therapeutic relevance. We have instituted a multimodal platform for molecular testing in B-ALL performing WGS/WTS in parallel with deep NGS-based immunoglobulin (IG) rearrangement MRD and exploratory DNA-breakpoint based MRD assays. We aimed to determine the utility of this approach for subtype classification compared to a standard-of-care diagnostic approach of CC/FISH testing.Forty-two consecutive adult patients underwent both standard-of-care diagnostic testing and WGS/WTS. 20/42 (48%) patients had an abnormal CC/FISH result supporting classification into recognized molecular subgroups. WGS/WTS assessment incorporating somatic coding and non-coding mutations, structural variants, fusions, copy number abnormalities and gene expression subtype prediction (ALLSorts, https://github.com/Oshlack/ALLSorts) was performed with concordant results in all 20 patients. 16/22 patients that were unclassified by CC/FISH were successfully reclassified by WGS/WTS including subtypes enriched for cryptic rearrangements (Ph-like, DUX4, MEF2D) and groups characterized by heterogeneous genomic alterations or a distinctive gene expression signature (PAX5alt, ZEB2/CEBP). A low hypodiploid karyotype was observed in two cases with an apparently normal karyotype by CC. The six patients who remained without a subtype defining driver genetic alteration after comprehensive testing frequently harbored novel IGH translocations or a Ph-like expression signature but without a described fusion.In order to understand the relative contribution from WGS versus WTS, analysis of 36 patients was performed using a truth classification. WGS and WTS produced equivalent classifications for 22 cases. Two cases were based solely on WGS findings (iAMP21 and ZEB2/CEBP) and three cases were based solely on WTS findings (DUX4). Importantly the combination of both WGS and WTS was critical to correctly classify nine cases (Ph-like and PAX5alt).MRD was assessed by a sensitive NGS assay to IG rearrangements (Adaptive Biotechnologies) and by quantitative probe-based droplet digital PCR (ddPCR) assays designed to structural rearrangement DNA breakpoints from genome data (analytical sensitivity 10 -4). Patient-specific ddPCR assays were designed to eight structural variants (KMT2A and IGH translocations, and IKZF1 deletions) in seven patients and assessed in 36 remission samples with parallel testing by multiparametric flow cytometry (MFC). Concordant MFC and ddPCR was observed in 30/36 samples (19 MRD pos, 11 MRD neg). Discordances included two MRD pos by MFC-only and four MRD pos by ddPCR-only; the latter often occurring in the setting of antigen directed therapy or in ALL with a less informative immunophenotype, demonstrating the additional utility of non-MFC based MRD assessment in specific clinical settings. 27/42 patients in our cohort had ≥1 genomic structural rearrangement identified by WGS that could be used for patient-specific MRD monitoring to complement existing MRD assessment.In conclusion WGS/WTS provided a molecular subtype classification in 86% of our cohort compared to 48% by standard-of-care diagnostic testing highlighting that CC/FISH alone is inadequate for contemporary molecular classification of B-ALL, which may have implications for treatment decisions. Importantly, the combination of WGS and WTS was superior to WGS-only or WTS-only for correct molecular subtype assignment. This approach has the potential to improve risk assessment in adult B-ALL and the routine feasibility, improvement in clinical outcomes and health economic impact warrant further assessment. DisclosuresBajel: Abbvie, Amgen, Novartis, Pfizer: Honoraria; Amgen: Speakers Bureau. Dickinson: Janssen: Consultancy, Honoraria; Amgen: Honoraria; Celgene: Research Funding; Gilead Sciences: Consultancy, Honoraria, Speakers Bureau; MSD: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda: Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Other: travel, accommodation, expenses, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau. Tiong: Servier: Consultancy, Speakers Bureau; Amgen: Speakers Bureau; Pfizer: Consultancy.

Duplex Sequencing for Ultra-Low Frequency Measurable Residual Disease Detection in Adult Acute Myeloid Leukemia

Background:The presence of measurable residual disease (MRD) is strongly associated with treatment outcomes in acute myeloid leukemia (AML). However, > 20% of MRD negative cases (as assessed by flow cytometry) subsequently relapse. We sought to determine if ultrasensitive Duplex Sequencing (DS), which relies on double-stranded consensus-making to achieve an error rate below one-in-ten-million, yields better prognostic performance via molecular MRD detection.Methods:Retrospective targeted DNA sequencing of 29 genes recurrently mutated in adult AML was performed on paired diagnostic and remission bone marrow samples from patients enrolled on the SWOG trial S0106 (randomized 7+3 versus 7+3 + gemtuzumab ozogamicin (GO)). Patients were selected if they had remission samples with flow cytometry results (n=67). Non-error corrected sequencing was performed on diagnostic samples (average depth 279x) and DS was performed on remission samples (average duplex molecular depth 27,002x). For each patient, potential germline variants were identified and excluded from the analysis if the variant allele fraction (VAF) was ≥ 35% at both diagnosis and remission, or ≥ 40% at either time point and a gnomAD allele frequency ≥ 0.05. Somatic variants present at diagnosis were classified as potentially deleterious if computationally predicted as such and with a VAF ≥ 5% (≥ 1% for FLT3-ITD/NPM1 insertions). For analysis of residual disease in remission, we evaluated the following outcomes (events): overall survival (OS; death), relapse-free survival (RFS) and time to relapse (TTR; relapse with death a competing event). All outcomes were measured from date of morphologic remission to date of event, with patients without event censored at date of last contact. Associations between residual disease and outcomes were assessed using Cox regression models (cause-specific model for TTR).Results:The median age was 48 years (range 8-60). 32 patients were randomized to 7+3 and 30 to 7+3+GO. A total of 172 potentially deleterious variants were identified in the diagnostic samples. Variants had an average VAF of 31% (range 1.4-91.5%) at diagnosis and were detected in 23 of the 29 genes, with FLT3 being the most frequently mutated. Of the 67 patients analyzed, 93% (n=62) had at least one variant detected at diagnosis (median 2, range 0-9) and 68% (n=42) had at least one residual diagnostic variant also found in the remission sample.We defined the presence of DS MRD as non-DTA (DNMT3A, TET2, ASXL1) time-of-diagnosis mutations identified at the remission time point with a VAF > 0.1% and/or an NPM1 VAF > 0.01% (PMID:31860405). DS MRD was strongly associated with all outcomes, with hazard ratios (and 95% CI) for TTR: 7.1 (2.7-18.9); RFS: 4.9 (2.2-10.9) and OS: 5.1 (2.1-12.3).As a comparator, we correlated treatment outcomes with the results of a flow cytometry MRD assay previously carried out on the same samples during the S0106 trial. The prognostic association of flow MRD with TTR, RFS and OS was less strong (i.e., a smaller hazard ratio) than DS MRD, with TTR: 2.5 (0.9-6.7); RFS: 2.2 (0.9-5.4) and OS: 2.4 (1.0-6.1). RFS and TTR for DS MRD and flow cytometry are plotted below for the 62 patients with a variant detected at diagnosis.Comparing DS MRD with flow cytometry, discordance was found in 20 cases: 15 cases where DS was positive and flow negative, and 5 cases in the opposite direction. Among the 15 discordant cases with DS positive and flow negative, 9 relapsed and 2 died without relapse and 4 were alive without relapse at last contact. Among the 5 discordant cases with DS negative and flow positive, 1 relapsed, 1 died without relapse, and 3 were alive without relapse at last contact.Conclusions:Among the 67 patients evaluated in this prospectively collected study, the presence of MRD defined by DS was strongly associated with adverse disease outcomes. The vast majority of patients had at least one time-of-diagnosis mutation that could be tracked as a measure of MRD. When compared with flow cytometry, DS exhibited superior negative and positive predictive values for foretelling future relapse, although this could potentially reflect the historical version of the flow cytometry assay used. These findings suggest that DS is a powerful tool that could be used in patient management and for early treatment assessment in clinical trials. [Display omitted] DisclosuresHourigan: Sellas: Research Funding. Radich: Amgen: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees.

How to Improve Prognostication in Acute Myeloid Leukemia with CBFB-MYH11 Fusion Transcript: Focus on the Role of Molecular Measurable Residual Disease (MRD) Monitoring.

Acute myeloid leukemia (AML) carrying inv(16)/t(16;16), resulting in fusion transcript CBFB-MYH11, belongs to the favorable-risk category. However, even if most patients obtain morphological complete remission after induction, approximately 30% of cases eventually relapse. While well-established clinical features and concomitant cytogenetic/molecular lesions have been recognized to be relevant to predict prognosis at disease onset, the independent prognostic impact of measurable residual disease (MRD) monitoring by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR), mainly in predicting relapse, actually supersedes other prognostic factors. Although the ELN Working Party recently indicated that patients affected with CBFB-MYH11 AML should have MRD assessment at informative clinical timepoints, at least after two cycles of intensive chemotherapy and after the end of treatment, several controversies could be raised, especially on the frequency of subsequent serial monitoring, the most significant MRD thresholds (most commonly 0.1%) and on the best source to be analyzed, namely, bone marrow or peripheral blood samples. Moreover, persisting low-level MRD positivity at the end of treatment is relatively common and not predictive of relapse, provided that transcript levels remain stably below specific thresholds. Rising MRD levels suggestive of molecular relapse/progression should thus be confirmed in subsequent samples. Further prospective studies would be required to optimize post-remission monitoring and to define effective MRD-based therapeutic strategies.

Comparable Outcomes After Alternative and Matched Sibling Donor Hematopoietic Stem Cell Transplantation and the Role of Molecular Measurable Residual Disease for Acute Myeloid Leukemia in Elderly Patients

Allogeneic hematopoietic stem cell transplantation (HSCT) remains the most effective postremission therapy conferring the chance of cure for acute myeloid leukemia (AML), including elderly patients. Although the number of transplantations for elderly patients with AML (eAML) is increasing owing to greater availability of various graft sources together with the adoption of advanced supportive care and reduced-intensity conditioning (RIC) regimen, there are relatively limited data on the impact of donor type in eAML compared to younger patients. In addition, few studies have evaluated the role of pretransplantation measurable residual disease (MRD) in the elderly population. Given the lack of prospective comparative study, we retrospectively compared transplantation outcomes of elderly patient with AML receiving allo-HSCT from matched sibling donor (MSD-HSCT), matched unrelated donor (MUD-HSCT) or haploidentical related donor (Haplo-HSCT), or autologous HSCT (Auto-HSCT). A total of 154 patients with a median age of 63 years (range 60-74) underwent MSD-HSCT (n = 41), MUD-HSCT (n = 36), Haplo-HSCT (n = 55), or Auto-HSCT (n = 22) for AML. RIC regimens were used in the majority of patients. In Haplo-HSCT, T-cell-replete peripheral blood stem cells with unique RIC regimens using anti-thymocyte globulin (ATG)-based GVHD prophylaxis was used. In the analysis, adjustment for MRD status at the time of transplantation was performed. MRD was measured by the quantitative molecular assays of the targets, including RUNX1-RUNX1T1, CBFB-MYH11, and NPM1, or WT1 in the absence of abnormalities in the aforementioned targets. At a median follow-up of 48 months, survival rates were similar between different donor types, whereas nonrelapse mortality (NRM) was lower in MUD-HSCT compared to MSD-HSCT (P = .002). MSD-HSCT, in which the majority of patients received a conditioning regimen not including ATG, showed more frequent severe chronic graft-versus-host disease (cGVHD). The major causes of non-relapse deaths in MSD-HSCT were related to cGVHD (71%), whereas infectious complications were mainly related to NRM in Haplo-HSCT (50%) or Auto-HSCT (100%). In the MUD-HSCT, GVHD (57%) and infection (43%) contributed similarly to non-relapse death. Cytomegalovirus infection was more frequent in Haplo-HSCT. In multivariate models, pre-transplant MRD-positivity was an independent risk factor for relapse (P = .001), whereas older age (P = .002) and the hematopoietic cell transplantation-comorbidity index (P = .009) were useful in predicting NRM. The current study demonstrated comparable outcomes after alternative and matched sibling donor HSCT in eAML aged 60 years or older, and the results also suggest the necessity for more sophisticated strategies to reduce NRM or relapse according to each donor type. The usefulness of molecular MRD assays demonstrated herein will facilitate trials for MRD-driven decision-making or risk-adaptive approaches in eAML.

Measurable Residual Disease Detected by Multiparameter Flow Cytometry and Sequencing Improves Prediction of Relapse and Survival in Acute Myeloid Leukemia.

The clinically ideal time point and optimal approach for the assessment of measurable residual disease (MRD) in patients with acute myeloid leukemia (AML) are still inconclusive. We investigated the clinical value of multiparameter flow cytometry-based MRD (MFC MRD) after induction (n = 492) and two cycles of consolidation (n = 421). The latter time point was proved as a superior indicator with independent prognostic significance for both relapse-free survival (RFS, HR = 3.635, 95% CI: 2.433–5.431, P <0.001) and overall survival (OS: HR = 3.511, 95% CI: 2.191–5.626, P <0.001). Furthermore, several representative molecular MRD markers were compared with the MFC MRD. Both approaches can establish prognostic value in patients with NPM1 mutations, and FLT3, C-KIT, or N-RAS mutations involved in kinase-related signaling pathways, while the combination of both techniques further refined the risk stratification. The detection of RUNX1–RUNX1T1 fusion transcripts achieved a considerable net reclassification improvement in predicting the prognosis. Conversely, for patients with biallelic CEBPA or DNMT3A mutations, only the MFC method was recommended due to the poor prognostic discriminability in tracking mutant transcripts. In conclusion, this study demonstrated that the MFC MRD after two consolidation cycles independently predicted clinical outcomes, and the integration of MFC and molecular MRD should depend on different types of AML-related genetic lesions.

MRD assessment using NGS in patients with acute myeloid leukemia undergoing hematopoietic stem cell transplantation: Meta-analysis.

e19002 Background: The presence of measurable residual disease (MRD) preceding hematopoietic stem cell transplantation (HSCT) in acute myeloid leukemia (AML) is increasingly recognized as a risk factor for leukemic relapse and decreased survival. Over many years, attempts have been looking at developing tools to detect MRD; this includes multiparametric flow cytometry, quantitative polymerase chain reaction, and most recently, next-generation sequencing (NGS). NGS offers higher sensitivity and detection rate of disease-related gene mutations, thereby potentially improving disease outcomes. Our study sought to review the scientific literature that included NGS‐detected molecular MRD in patients with AML who underwent bone marrow transplantation. Methods: We performed a systematic search using PubMed, Google Scholar, EMBASE, and SCOPUS up until October 2020. Inclusion criteria included articles that reported the association between pre-HSCT MRD detected by NGS and post HSCT outcome in patients with AML. We extracted hazard ratios for the cumulative incidence of relapse (CIR), overall survival (OS) and leukemia free survival (LFS). A random-effect model was utilized to calculate the hazard ratio (HR) with a 95% confidence interval (CI). Results: Six studies met our inclusion criteria. Our meta-analysis showed that the detection of pre-transplant MRD by NGS was associated with increased risk of cumulative incidence of relapse (hazard ratio=2.5, CI= 1.6-3.9, with p-value &lt;0.001) and decreased overall survival (hazard ratio=1.6, CI= 1.6-2.3, p-value 0.005). LFS was significantly higher in those who had negative MRD detection by NGS before transplantation (HR=1.9, CI= 1.3-2.8 with p-value 0.001). These results were independent of the cytogenetic risk of conditioning intensity. There was heterogeneity between our studies (I2 = 53%, 52%, and 59% for CIR, OS, and LFS, respectively). Conclusions: The application of NGS to detect MRD is a strong predictor of outcome in patients with AML who are undergoing hematopoietic stem cell transplantation. NGS-detected MRD positive status prior to HSCT is indicative of a higher risk of relapse and decreased overall survival in this meta-analysis. Despite the limitations in our study, it demonstrates the value of MRD detection by NGS in HSCT recipients.

158 - Impact of Pre-Transplant Molecular Measurable Residual Disease (MMRD) and European Leukemianet (ELN) Genetic Classification in Clinical Outcomes for Acute Myeloid Leukemia (AML) Patients (Pts) Undergoing Allogeneic Stem Cell Transplantation (alloHCT)

158 - Impact of Pre-Transplant Molecular Measurable Residual Disease (MMRD) and European Leukemianet (ELN) Genetic Classification in Clinical Outcomes for Acute Myeloid Leukemia (AML) Patients (Pts) Undergoing Allogeneic Stem Cell Transplantation (alloHCT)

Molecular methods for measurable residual disease in acute myeloid leukemia: where are we and where are we going?

Measurable residual disease (MRD) testing has become a standard practice for patients with acute myeloid leukemia (AML) following therapy. However, MRD testing in AML is not straightforward, and both molecular methods and multiparameter flow cytometric (MFC) methods demonstrate clinical utility. While MFC methods are potentially applicable to all AML patients, current molecular MRD methods must be individually tailored to the patient’s AML disease genetics, a strategy that is currently applied for patients with acute promyelocytic leukemia, core binding factor AML, and AML with mutated NPM1. However, there is great interest in next-generation sequencing (NGS) methods for MRD assessment, an approach that could potentially be applied to all patients with AML. Current NGS methods have limited analytic sensitivity when compared with other molecular methods and MFC, but advances in NGS methods and informatic algorithms may improve NGS MRD testing in the near future. In this review, we discuss current recommendations for molecular MRD assessment in AML and discuss opportunities and challenges for MRD assessment by NGS methods.

Ultrasensitive Measurable Residual Disease (MRD) Detection in Acute Myeloid Leukemia (AML) Using a Targeted Next Generation Sequencing (NGS) Panel

INTRODUCTION: Assessment of MRD in AML is emerging as an important tool for refining risk classification and improving patient management and outcomes. MRD also shows promise as a surrogate endpoint to accelerate therapeutic development and may facilitate more robust post-transplant surveillance. Highly sensitive digital PCR (dPCR) methods such as BEAMing - which are 50-100X more sensitive than "pan-heme" NGS assays - have generated compelling data for therapeutic response monitoring and clearance of molecular MRD in clinical trials: for example, for both relapsed/refractory as well as newly diagnosed patients, declining levels and eventual clearance of IDH1 mutations correlated with more robust hematologic response (DiNardo CD et al. N Engl J Med. 2018, 378(25):2386-98; Daigle S et al. Presented at ASH 2019). Nevertheless, the complex clonal dynamics of AML demand broader coverage across more genomic regions than are currently able to be interrogated using dPCR. At the same time, NGS pan-heme panels that offer broad genomic coverage lack sufficient sensitivity to detect MRD, as their limits of detection (LoD) are between 1-5% mutant allele frequency (MAF). To overcome these limitations, we developed a highly sensitive assay based on the Safe-SeqS technology (SafeSEQ) to detect de novo mutations across genomic regions with established and emerging clinical validity for AML MRD. This highly sensitive error-corrected NGS-based workflow detects molecular MRD with an LoD comparable to dPCR assays such as BEAMing. METHODS: A multiplexed enrichment panel targeting 68 highly relevant genomic regions was developed for ultra-sensitive mutation detection across 57 exons spanning 20 genes: BCOR, BRAF, CEBPA, FLT3, GATA2, IDH1, IDH2, JAK2, KIT, KRAS, NPM1, NRAS, PRPF8, PTPN11, SETBP1, SF3B1, SRSF2, TP53, U2AF1, and ZRSR2. Initial analytical performance demonstration for the SafeSEQ AML MRD test examined limit of blank (LoB) as well as LoD at the 95% confidence level (LoD95). LoB was measured using wildtype (wt) gDNA prepared from two NIST cell lines run in replicate; LoD was determined through replicate testing of contrived materials containing 30 characterized mutations across different mutant molecule (MM)/ MAF tiers ranging from 20 MM down to &amp;lt;1 MM. Low and high DNA input levels were also tested, from 1,000 genomic equivalents (GE) up to a subset of tiers run at 20,000 GE (3.3-66 ng) to demonstrate performance irrespective of wt DNA amount. Direct evaluation of analytical and clinical performance between the SafeSEQ AML MRD panel and a subset of mutations detected using BEAMing is currently underway. RESULTS: A rank-based approach was used to evaluate the distribution of background signals observed in the wt cell line DNA across all interrogated base positions. Consistent with previous observations of LoB across different SafeSEQ panels, a very low level of background noise was observed, with the vast majority of bases exhibiting signal &amp;lt;1 MM, indicating robust analytical specificity. Importantly, there were no positions affected by elevated noise for which clinically relevant mutations have been characterized for AML. For the variant-positive contrived materials run in replicate across different mutation levels, hit rates were consistent with those observed in other SafeSEQ assays and yielded 95% detection at 5 MM; this corresponds to 0.025% and 0.5% MAF for 20,000 and 1,000 GE inputs, respectively. Hit rates for the different MM tiers were also consistent between low and high DNA input levels, indicating robust performance for mutation detection across a wide range of background wt DNA. CONCLUSIONS: The SafeSEQ AML MRD assay demonstrates ultra-sensitive detection of low frequency mutations, with an LoD95 of 5 MM (0.025% MAF for 20,000 GE DNA input), while specificity remains very high. Similar to other SafeSEQ platform configurations, this performance is comparable with data obtained using the BEAMing dPCR technology; it is also orders of magnitude more sensitive than broad pan-heme NGS tests. With this combination of ultra-high analytical sensitivity paired with clinically-informed genomic coverage, we anticipate the SafeSEQ AML MRD test will play a fundamental role in accelerating therapeutic development. It should also provide clinicians with more reliable MRD information at important decision points, such as pre-transplant, or when considering novel maintenance therapies. Disclosures Sloane: Sysmex Inostics, Inc: Current Employment.

First-in-Human Phase I Dose Escalation and Expansion Study Evaluating the Fc Optimized FLT3 Antibody Flysyn in Acute Myeloid Leukemia Patients with Minimal Residual Disease

Even when achieving morphological complete remission (CR) after induction therapy, roughly half of acute myeloid leukemia (AML) patients display measurable residual disease (MRD) and eventually relapse. The surface receptor FLT3/CD135 is expressed on AML cells in almost all patients and constitutes a highly selective target antigen for immunotherapy, as expression on healthy tissues is limited to low levels on dendritic cells, monocytes and hematopoietic progenitor cells. FLYSYN is a chimeric Fc-optimized IgG1 antibody that binds specifically and with high avidity to human FLT3 (CD135). Here we report updated results of an open-label, single-arm, first in man multicenter trial (recruitment March 2017 to March 2020) evaluating safety/tolerability and preliminary efficacy of FLYSYN in patients with AML (NCT02789254). Morphological CR with stable or increasing MRD in two sequential measurements using central RT-qPCR and/or next generation sequencing (NGS) constituted the main inclusion criterion. FLYSYN was administered i.v. over 3 h as single application in cohorts 1-5 (0.5 mg/m², 1.5 mg/m², 5 mg/m², 15 mg/m², 45 mg/m²); in cohort 6, 15 mg/m² were applied on day 1, 15 and 29. Three patients were treated per cohort except for cohorts 4 and 6, which were expanded to comprise 9 and 10 patients, respectively. Molecular response was defined as &amp;gt;1 log MRD reduction or negativity in bone marrow (BM). In total, 31 patients (median age 58 years; range, 21-80 years; male:female ratio: 1:1.8) were enrolled, of which 27, 3 and 1 were MRD-positive for mutated NPM1, mutated IDH2 and RUNX1-RUNX1T1, respectively. Based on pharmacokinetic analysis, the half-life of FLYSYN was estimated to be 6.5 days. In 8 patients (26%), a transient decrease of neutrophil count (2 adverse events (AEs) grade 3, others ≤ grade 2) was observed. No relevant effect on stem cell reserve as assessed by colony forming unit assays was detected in the so far analyzed 26 patients. No other AE &amp;gt; grade 2 or dose-limiting toxicity were observed. The most frequent AEs were unspecific and comprised fatigue and flu like symptoms (12%), musculoskeletal symptoms (8%) and laboratory abnormalities (42%). With regard to efficacy, molecular response to treatment was achieved in 11/31 patients (35%), with so far two patients achieving MRD negativity documented one year after treatment. Among the patients receiving 45 mg/m2 FLYSYN (in total, upon single or repetitive dosing), objective responses were achieved in 46% (6/13) cases, whereas 28% (5/18) responded to treatment with lower doses. Together, the results of our phase I trial demonstrate that FLYSYN is safe and very well tolerated as monotherapy in AML patients with molecular MRD. Early efficacy data are promising and warrant further evaluation in an up-coming phase II clinical trial. Disclosures Heuser: PriME Oncology: Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Stemline Therapeutics: Consultancy; Janssen: Consultancy; Astellas: Research Funding; Roche: Research Funding; BerGenBio ASA: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Bayer: Consultancy, Research Funding; Amgen: Research Funding; Karyopharm: Research Funding; Abbvie: Consultancy. Thol:Astellas: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Kapp-Schwoerer:Jazz Pharmaceuticals: Honoraria, Research Funding. Grosse-Hovest:Synimmune: Current Employment. Steiner:Synimmune: Current Employment. Schlenk:Roche: Research Funding; Novartis: Speakers Bureau; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accomodations, Expenses, Research Funding, Speakers Bureau; PharmaMar: Research Funding; AstraZeneca: Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Salih:Pfizer: Consultancy; Medigene: Consultancy; Novartis: Consultancy; Philogen: Consultancy; Synimmune: Consultancy, Research Funding.

Molecular Measurable Residual Disease Detection in Acute Myeloid Leukemia Using Error Corrected Next Generation Sequencing

Introduction The monitoring of a patient's response to chemotherapy, called, measurable residual disease (MRD) is one of the most important predictors of outcome in Acute Myeloid Leukemia (AML). Although universally applicable, FCM-MRD for AML suffers from low sensitivity as compared to precursor B lineage acute lymphoblastic leukemia. Here, we evaluated the clinical utility of error corrected next generation sequencing (NGS) to detect MRD (NGS-MRD) in AML using single molecule molecular inversion probes (smMIPS). We compare NGS-MRD and FCM-MRD and determine their impact on patient outcome. We demonstrate that error corrected NGS-MRD at early timepoints in therapy is an independent and significant predictor of outcome in patients of AML treated with conventional therapies. Methods We created a 35 gene "hotspot" panel comprising of a pool of 302 smMIPS. In brief, this panel covers regions of 35 commonly mutated genes in AML.FLT3-ITD were detected using a novel one-step PCR based NGS assay. Post mapping, singleton reads (originating from one UMI) were discarded and consensus family based variant calling was performed. We then created a site and mutation specific error model to ascertain the relevance of an observed variant at each site. A limit of detection (LOD) experiment demonstrated a lower detection limit of 0.05%. For FLT3-ITD the LOD was 0.002%. A total of 393 adult patients of AMLwere accrued over a period of six years.Patients were treated with standard 3+7 induction followed by 3 doses of HiDAC. Allogeneic bone marrow transplantation was offered where feasible. Somatic mutations at diagnosis were evaluated using a smMIPS based 50 gene myeloid panel which was applicable to 327 patients [83.2% of AMLs, median 2 mutations per case (range 1 - 6 trackable mutations)].MRD assessment could be performed in 201 adult patients of AML in morphological remission (not performed in the rest because of suboptimal quality DNA at MRD time points or missing sample).Samples were sequenced on multiple S4 flow cells of a NovaSeq 6000 using 150PE chemistry.FCM-MRD was obtained from the bone marrow at end of induction (PI, n=200) and end of first consolidation cycle (PC, n=98). NGS-MRD sample also obtained at the same time points (PI, n=196&amp; PC, n=127) from the bone marrow (n=266) or peripheral blood (n=45). Results The interaction of mutations that were trackable at diagnosis can be seen in Figure 1A. A total of 345 mutations could be detected in 196 patients (Figure 1B) with a median VAF of 1.01% [0.82% after exclusion of mutations in DNMT3A, TET2, ASXL1 (DTA) genes; (median of 2 mutations for PI and one for PC timepoint)]. The median consensus read coverage was 11,127 for the smMIPS assay, whereas for the FLT3-ITD assay it was 13,96,366.The median follow-up of the cohort was 42.3 months. The presence of NGS-MRD (70.9%) was associated with inferior overall survival (OS; p=0.001) [hazard ratio(HR)- 2.24; 95% confidence interval (CI)- 1.47 to 3.43] and relapse free survival (RFS; p=0.0002) [HR- 2.28; 95% CI- 1.58 to 3.31] at PI time point as well as PC time points [40.94% positive; OS (p=0.008)(HR- 1.92; 95% CI- 1.14 to 3.22) and RFS (p=0.004)(HR- 1.90; 95% CI- 1.18 to 3.05)].Similarly, FCM-MRD (44%) was predictive of inferior OS (p=0.0002)(HR- 2.08; 95% CI- 1.38 to 3.13)and RFS (p=0.0008)(HR- 1.81; 95% CI- 1.26 to 2.60) at PI as well as PC time points [21.4% positive, OS (p=0.04)(HR- 1.87; 95% CI- 0.89 to 3.91) and RFS (p=0.001)(HR- 2.38; 95% CI- 1.17 to 4.81)]. On multivariate analysis post induction NGS MRD emerged as the most important independent prognostic factor predictive of inferior outcome for OS [HR- 1.94; 95% CI-1.15 to 3.27; (p&amp;lt;0.0001)]as well asRFS[HR-2.05; 95% CI-1.30 to 3.23; (p&amp;lt;0.0001)].On incorporating results combining both the MRD modalities,patients that were positive by both techniqueshad a significantly inferior outcome with respect to OS (p=0.0002; HR- 4.66; 95% CI- 2.71 to 8.0)and RFS (p=0.0001; HR- 4.03; 95% CI- 2.51 to 6.47) at PI timepoint as well as PC timepoint [OS (p=0.02; HR- 3.73; 95% CI- 1.07 to 12.97) and RFS (p=0.0015; HR- 4.17; 95% CI- 1.27 to 13.7)] as compared to patients negative by both modalities (Figure 1E,F) Conclusion In conclusion, we demonstrate that error corrected panel-based sequencing is feasible for MRD monitoring in AML and may offer an advantage over existing techniques. Maximum clinical utility may be leveraged by combining FCM and NGS modalities. Figure Disclosures No relevant conflicts of interest to declare.

Safety and Antitumor Effects of CD19-Specific Autologous Chimeric Antigen Receptor-Modified T (CAR-T) Cells Expressing the Inducible Caspase 9 Safety Switch (iC9-CAR19 T Cells) in Adult Acute Lymphoblastic Leukemia (ALL)

Safety and Antitumor Effects of CD19-Specific Autologous Chimeric Antigen Receptor-Modified T (CAR-T) Cells Expressing the Inducible Caspase 9 Safety Switch (iC9-CAR19 T Cells) in Adult Acute Lymphoblastic Leukemia (ALL)

Prognostic value of MRD monitoring based on BCR-ABL1 copy numbers in Philadelphia chromosome positive acute lymphoblastic leukemia

Assessment of measurable residual disease (MRD) has emerged as a powerful prognostic tool in pediatric and adult acute lymphoblastic leukemia (ALL). In this single-centre retrospective study, we evaluated the prognostic relevance of MRD based on BCR-ABL1 copy numbers in Ph + ALL patients between 2006 and 2018. Molecular responses were evaluated at 3, 6, 9 and 12 months after the initiation of treatment. Patients who had their MRD assessed at three or more time points were categorized into MRD good risk or poor risk based on BCR-ABL1/ABL1 copy number ratio. MRD positive patients consistently showed a trend toward poor survival and on multivariate analysis, MRD poor risk patients had adverse outcomes when compared to MRD good risk patients in terms of overall (OS; p = .031) and event-free (EFS; p < .001) survival. In conclusion, molecular MRD based on BCR-ABL1 copy number ratio is an ideal prognostic indicator in Ph + ALL patients undergoing treatment.

Molecular MRD status and outcome after transplantation in NPM1-mutated AML

AbstractRelapse remains the most common cause of treatment failure for patients with acute myeloid leukemia (AML) who undergo allogeneic stem cell transplantation (alloSCT), and carries a grave prognosis. Multiple studies have identified the presence of measurable residual disease (MRD) assessed by flow cytometry before alloSCT as a strong predictor of relapse, but it is not clear how these findings apply to patients who test positive in molecular MRD assays, which have far greater sensitivity. We analyzed pretransplant blood and bone marrow samples by reverse-transcription polymerase chain reaction in 107 patients with NPM1-mutant AML enrolled in the UK National Cancer Research Institute AML17 study. After a median follow-up of 4.9 years, patients with negative, low (<200 copies per 105ABL in the peripheral blood and <1000 copies in the bone marrow aspirate), and high levels of MRD had an estimated 2-year overall survival (2y-OS) of 83%, 63%, and 13%, respectively (P < .0001). Focusing on patients with low-level MRD before alloSCT, those with FLT3 internal tandem duplications(ITDs) had significantly poorer outcome (hazard ratio [HR], 6.14; P = .01). Combining these variables was highly prognostic, dividing patients into 2 groups with 2y-OS of 17% and 82% (HR, 13.2; P < .0001). T-depletion was associated with significantly reduced survival both in the entire cohort (2y-OS, 56% vs 96%; HR, 3.24; P = .0005) and in MRD-positive patients (2y-OS, 34% vs 100%; HR, 3.78; P = .003), but there was no significant effect of either conditioning regimen or donor source on outcome. Registered at ISRCTN (http://www.isrctn.com/ISRCTN55675535).

Patient-Tailored Deep Sequencing of Peripheral Blood Enables Early Detection of Relapse in Childhood Acute Myeloid Leukemia

Relapse remains a major therapeutic challenge in children with acute myeloid leukemia (AML). Outcome after relapse may improve if preemptive therapy is initiated at first evidence of leukemia regrowth. Early detection of imminent relapse requires molecular measurable residual disease (MRD) monitoring after therapy completion. Today, this is possible only in about 40% of children with AML that harbor genetic abnormalities applicable for quantification using standardized qPCR assays. To enable disease surveillance for all patients, we developed patient-tailored deep sequencing (DS) MRD analysis, which provides highly sensitive detection of leukemia-specific mutations. We investigated the potential of this method for early relapse detection in peripheral blood (PB), the only easily accessible source for MRD sampling in children. PB samples were collected at monthly intervals during follow-up from 45 children diagnosed with AML and treated according to The Nordic Society of Pediatric Haematology and Oncology (NOPHO)-DBH AML 2012 protocol between January 2013 and May 2016 in Denmark, Norway, Sweden and Finland (508 samples, median 11 samples/patient, range 3-27). Nine patients with relapse (median age 5 years, range 0-8) had available diagnostic and relapse material and were included in this study. The patients displayed core binding factor abnormalities (n=3), KMT2A-rearrangements (n=3), monosomy 7 (n=1) or normal karyotype (n=2) at AML diagnosis. Leukemia-specific single nucleotide variants (SNVs) were identified with exome sequencing (ES) of sorted leukemic cells with lymphocytes or remission PB as constitutive DNA template. A variant allele frequency (VAF) with 95% confidence interval including 50% indicates presence of the mutation in all leukemic cells at diagnosis. With the exception of 2 cases with only subclonal mutations at diagnosis, leukemia-specific SNVs with VAF of 50% at diagnosis and persistence at relapse were selected as MRD targets. MRD target mutations were quantified in PB samples preceding overt relapse using patient-tailored DS assays with sensitivity of VAF 0.02%. In diagnostic samples, ES identified 53 leukemia-specific SNVs (median 4 SNVs/patient, range 2-12) of which 33 were also present at relapse (median 2 SNVs/patient, range 1-9). The number of mutations identified at diagnosis increased with age (Rs 0.83, p=0.006). All patients had at least one leukemia-specific SNV detected at both diagnosis and relapse. Twenty-one MRD target mutations (median 2 SNVs/patient, range 1-3) were quantified in PB (55 samples, median sampling interval 28 days, range 11-80) using DS. In 8/9 patients, at least one SNV was detected in PB before overt relapse occurred. The first PB sample showing MRD positivity (median VAF 0.14%, range 0.03-0.44) preceded hematological relapse at a median interval of 3 months (range 0-7.9). In 6 patients not preemptively treated, the median doubling time based on VAF increments was 7 days, with great variability between individuals and genotypes (range 4-28 days). Three patients had molecular relapse diagnosed by qPCR used in clinical diagnostics and received individualized preemptive treatment. In these 3 patients, DS detected mutations in PB for &amp;gt;100 days preceding overt relapse and the doubling times were 14, 25 and 36 days. In conclusion, DS of leukemia-specific mutations at frequent intervals in PB enables early detection of relapse and ES at diagnosis may identify SNVs applicable for such longitudinal MRD monitoring. This approach facilitates molecular disease surveillance and initiation of preemptive therapy in AML patients without established qPCR targets. Disclosures No relevant conflicts of interest to declare.

Impact of FLT3-ITD Remission Depth in Acute Myeloid Leukemia Patients Prognosis Prediction before Allogeneic Hematopoietic Cell Transplantation

Introduction: Activating internal tandem duplication of FMS-like tyrosine kinase 3 (FLT3-ITD) is one of the most frequently mutations in acute myeloid leukemia (AML) patients with a frequency of 20-30%. Although AML with FLT3-ITD mutation is not recognized as a distinct entity in the World Health Organization classification system, AML patients with FLT3-ITD usually have high white blood cell count, high risk in poor prognostic outcome and are benefited from FLT3 inhibitors. However, the outcome prediction of AML with FLT3-ITD is still not very clear in patients undergoing allogeneic hematopoietic cell transplantation (alloHCT). Recent studies showed that the depth of remission, mostly accessed by flow cytometry (FCM) based measurable residual disease (MRD) and next generation sequencing based molecular MRD, was highly predictive for relapse in AML before alloHCT. The depth of remission is considered an important criterion for evaluating AML relapse before alloHCT. Hence, FLT3-ITD remission depth showed a potential application in evaluating FLT3-ITD subtype's prognosis. Therefore, in this retrospective study we tried to evaluate prognostic impact of FLT3-ITD remission depth in AML before alloHCT. Methods: A total of 117 FLT3-ITD positive patients were obtained in our study if they were 18 years or older, had a diagnosis of AML excluding acute promyelocytic leukemia, received standard induction chemotherapy comprising anthracycline and cytoarabine, at first affiliated hospital of Soochow University between September 2011 to January 2018 . All patients were examined a panel of 51 genes mutation by next generation sequencing and FLT3-ITD allelic ratio (AR) in newly diagnosed bone marrow samples (Fig1 A). 57 patients received two courses of standard chemotherapy and immediate alloHSCT in four months. The median time from first chemotherapy to alloHSCT was 99 days. FLT3-ITD was also examined direct after secondary chemotherapy with the sensitivity level of 0.005. Distribution of OS and RFS were estimated by Kaplan-Meier method. Difference of FLT3-ITD positive ratio in FLT3-ITD subtypes was analyzed by Chi-squared test. The two-sided level of significance was set at p&amp;lt;0.05. The deadline for follow-up was May 31, 2019, with a median follow-up time of 24 (5-83) months. Results: In our cohort, the median FLT3-ITD AR of 117 patients was 0.53 (range 0.02-7.72) in newly diagnosis. Interestingly, patients with DNMT3A mutation (0.615, range 0.04-7.72) had a higher FLT3-ITD AR than those of patients with CEBPA double mutation (0.19, range 0.02-0.74), with statistical difference (p=0.007). Patients with DNMT3A mutation also had lower complete remission rate than those of patients with NPM1 mutation and DNMT3A wildtype after first chemotherapy (x2=5.987, P=0.018). In 57 patients undergoing alloHSCT, we found there were no differences in OS and RFS among patients classified by FLT3-ITD AR or concomitant NPM1 mutation. However, patients with FLT3-ITD positive had a poorer OS (p&amp;lt;0.001) and RFS (p&amp;lt;0.001) than those of patients with FLT3-ITD negative accoding to the FLT3-ITD states after secondary chemotherapy. In addition, patients with FLT3-ITD AR&amp;gt;0.01 had a poorer OS and EFS than those of patients with FLT3-ITD AR&amp;lt;0.01, indicating FLT3-ITD remission depth is helpful in prognosis prediction for patients undergoing alloHCT (Fig1 B,C). Moreover, we found patients with DNMT3A mutation had a higher FLT3-ITD positive ratio than those of patients with NPM1 mutation after secondary chemotherapy. This result was also found in patients with normal chromosome karyotype (NK). There was no FLT3-ITD positive in patients with CEBPA double mutation or t(8;21) after secondary chemotherapy in our cohort, while 4 of 8 patients with chromosome karyotype abnormalities (no favorable) had FLT3-ITD positive after secondary chemotherapy. From these results above, we finally found patients with DNMT3A mutation had a poorer OS and EFS in NK patients undergoing alloHCT(Fig1 D,E). In conclusion, our results suggested FLT3-ITD remission depth is useful in prognosis prediction for AML patients with FLT3-ITD before alloHCT. Figure Disclosures No relevant conflicts of interest to declare.

Post-Transplant Flow Cytometry MRD Predicts Relapse in a Real World AML Cohort

Previous data indicate that pre-transplant flow cytometry measurable residual disease (MRD) in acute myeloid leukaemia (AML) patients in complete remission predicts relapse and survival. Diagnostic laboratories have started to report flow MRD (fMRD) at each AML disease assessment. We evaluated 83 consecutive patients with AML receiving allogeneic stem cell transplants at King's College Hospital (London, UK) in 2017-2018 to assess the significance of fMRD pre- and post-transplant. Flow MRD detection was based on leukaemia associated immunophenotype and 'difference from normal' strategies, reported at a sensitivity of 0.1%. Two timepoints were assessed: pre-transplant (post-induction) and day 100 post-transplant. Pre-transplant, 30 patients were excluded (9 active disease, 21 unknown fMRD) - of the remaining 53 patients in remission (&lt;5% blasts by morphology), 15 were fMRD+ and 38 fMRD-. At day 100 post-transplant, 16 patients were excluded (14 died/relapsed, 2 no fMRD results) - of the remaining 67 patients, 7 were fMRD+ and 60 fMRD- at last assessment. Median follow up was 394 days (range 21-825) from transplant. Patient characteristics at each timepoint are listed in Tables 1 and 2. Outcome measures were overall survival (OS), relapse free survival (RFS), relapse and non-relapse mortality (NRM). Multivariate Cox regression analysis was performed using the parameters listed in the tables. Pre-transplant, the only predictor of OS was recipient CMV positivity - HR 0.07 (95% CI 0.01-0.79), p=0.03. RFS was predicted by age ≥65 - HR 0.18 (95% CI 0.05-0.65), p=0.01, secondary AML (sAML) - HR 0.19 (95% CI 0.05-0.77), p=0.02 and CMV positivity - HR 0.16 (95% CI 0.04-0.69), p=0.01. Relapse was predicted by age ≥65 - HR 10.98 (95% CI 1.68-71.73), p=0.01, genetic risk: favourable versus adverse - HR 0.02 (95% CI 0.001-0.04), p&lt;0.01, sAML - HR 14.53 (95% CI 1.26-167.13), p=0.03, performance status &lt;90% - HR 13.35 (95% CI 1.39-128.59), p=0.03, CMV positivity - HR 9.30 (95% CI 1.00-86.38), p=0.05 and fMRD+ - HR 4.75 (95% CI 1.25-18.08), p=0.02. No parameter predicted NRM. A separate pre-transplant analysis was performed to include molecular MRD (mMRD). Fifty three patients were excluded (9 active disease, 50 not assessed for mMRD, 1 no available result) - in the remaining 23 patients (21 NPM1 mutated, 2 KMT2A rearranged), mMRD was not predictive of any outcome. Eight patients remained mMRD+ in remission post-transplant; 3 were initially mMRD- post-transplant, but became mMRD+ later. Only 2/11 patients relapsed - the others responded to augmentation of the graft versus leukaemia (GVL) effect by reduction of immunosuppression or donor lymphocyte infusion (DLI). At day 100 post-transplant, OS was predicted by age ≥65 - HR 0.001 (95% CI 2×10-6-0.23), p=0.01 and sAML - HR 0.002 (95% CI 3.6×10-5-0.11), p&lt;0.01. RFS was predicted by CMV positivity - HR 0.07 (95% CI 0.01-0.34), p&lt;0.01, fMRD+ - HR 0.04 (95% CI 0.01-0.36), p&lt;0.01 and DLI - HR 8.93 (95% CI 1.23-64.54), p=0.03. Relapse was predicted by therapy-related AML - HR 10744.98 (95% CI 1.63-71043020.5), p=0.04, CMV positivity - HR 2297.13 (95% CI 6.38-826805.30), p=0.01, fMRD+ - HR 5475.48 (95% CI 27.04-1108709.83), p&lt;0.01 and DLI - HR 0.02 (95% CI 0.002-0.30), p&lt;0.01. No parameter predicted NRM. In our cohort, recipient CMV positivity was strongly associated with poor outcomes. Age, genetic risk and secondary disease were also important. Pre-transplant fMRD was predictive of relapse but not survival. At day 100 post-transplant, fMRD predicted both relapse and RFS; DLI was associated with a protective effect. Median time to relapse from fMRD+ at day 100 post-transplant was 89 days - relapse occurred in 5/7 patients. This contrasts with the sensitivity of NPM1 mMRD+ disease to the GVL effect. Further work is required both to confirm our findings in a larger cohort and to determine how best to manage patients who are fMRD+ post-transplant. Disclosures Off Label Use: Azacitidine (Vidaza) - used for prevention of relapse after allogeneic stem cell transplantation for acute myeloid leukaemia. de Lavallade:Bristol Myers Squibb: Research Funding. Mufti:Celgene: Consultancy, Research Funding. OffLabel Disclosure: Azacitidine (Vidaza) - used for prevention of relapse after allogeneic stem cell transplantation for acute myeloid leukaemia

Clinician-friendly reports of molecular measurable residual disease monitoring in acute promyelocytic leukemia.

Molecular measurable residual disease (MRD) monitoring based on real-time quantitative reverse transcription PCR (RT-qPCR) plays an important role in acute promyelocytic leukemia (APL) management, but the performance status of clinical reports is unknown. This study focuses on the specific elements in molecular MRD monitoring report and their impact on clinical decision-making. The participating laboratories were asked to submit real and formal clinical reports for mock samples panel with APL clinical case. The MRD-specific elements were analyzed and summarized. The significance of longitudinal MRD monitoring curve and the missing MRD-specific elements for clinical decision-making were assessed. MRD-specific elements were significantly missing in clinical reports. The element "testing results" existed great inconsistencies in the written form of testing items and data. The longitudinal MRD monitoring curve of false-negative or false-positive MRD result was obviously different from all-correct. It not only identified MRD time point of tissue sampling relative to treatment and ensured the reliability of the negative MRD results, but also gave MRD diagnosis, clinical interpretation, and further recommendation. Clinician-friendly reports with MRD-specific elements can better serve clinical practice. The correctly intuitive results and clinically important MRD-specific elements can provide a good description of the reliability and clinical significance of MRD results.