Impact Of Minimal Residual Disease Research Articles

Influence of Minimal Residual Disease at Day 15 of Induction Therapy on Survival of Children with Acute Lymphoblastic Leukemia.

The aim of the study was to evaluate the impact of minimal residual disease (MRD) on day 15 of induction therapy (d15) on the treatment outcome in children with acute lymphoblastic leukemia (ALL). The study included 74 patients (1-18 years) with ALL, who were treated at the Pediatric Clinic of the University Clinical Center Banja Luka from January 2011 to May 2021. All patients were treated according to ALL IC-BFM 2009 protocol. MRD on bone marrow was assessed d15, using the multiparameter flow cytometry method (FCM). Of all, 59.46% of patients had MRD d15 0.1-10%, MRD<0.1% had 18.92% of patients, and 21.62% had MRD >10%. Patients with the lowest MRD had the highest 5-year overall survival (OS) and event-free survival (89.5% and 91% respectively) and the lowest cumulative risk for relapse or death (9.7% and 8.1%), in contrast to patients with MRD>10% in whom OS was 80.0%, and the risk of recurrence is 20%. Predicted MRD d15 was significantly associated with prednisone response assessed in the peripheral blood on day 8 (P<0.001) and statistically significantly positive correlation (r=0.498; P<0.001) was found. MRD measurement d15 has a great prognostic significance for patients in the standard and high risk groups, but not for patients in the intermediate risk group. The introduction of additional testing is necessary for better identification of patients with an increased risk of disease recurrence.

Real-world prognostic significance of attaining minimal residual disease negativity in newly diagnosed multiple myeloma

The aim of the study was to evaluate the prognostic impact of minimal residual disease (MRD) in the real-world setting and the interaction between MRD and molecular risk, clinical response and autologous stem-cell transplant (ASCT). A retrospective analysis of 275 newly diagnosed multiple myeloma (NDMM) patients who achieved very good partial remission (VGPR) or better before maintenance were involved. We examined MRD status by multiparameter flow cytometry (MFC). At a median follow-up of 37 months (4–88 months), In patients who achieved ≥ VGPR, those with MRD negativity had significantly longer PFS (51 vs. 26 months; P < 0.001) and OS (Not reached: NR vs. 62 months, P < 0.001) than those with MRD positivity. MRD positivity was the independent prognostic factor for PFS with hazard ratios of 2.650 (95% CI 1.755–4.033, P < 0.001) and OS with hazard ratios of 2.122 (95% CI 1.155–3.899, P = 0.015). Achieving MRD negativity was able to ameliorate a poor prognosis associated with genetic high risk. MRD negativity was associated with better PFS regardless of ASCT treatment. MRD status was more predictable for clinical outcome than conventional clinical responses. Moreover, Sustained MRD negativity ≥ 12 or ≥ 24 months improved both PFS and OS. Patients with NDMM who achieved MRD-negative status or sustained MRD negativity had deep remission and improved clinical outcomes regardless of high-risk cytogenetics, ASCT and clinical responses in a real-world setting.

Hematopoietic Stem Cell Transplantation in Acute Promyelocytic Leukemia in the Era of All-Trans Retinoic Acid (ATRA) and Arsenic Trioxide (ATO).

Acute promyelocytic leukemia (APL) currently represents one of the malignant hemopathies with the best therapeutic responses, following the introduction of all-trans retinoic acid (ATRA) and subsequently of arsenic trioxide (ATO) treatment. As a result, a large proportion of patients with APL achieve long-term responses after first-line therapy, so performing a hematopoietic stem cell transplant as consolidation of first complete remission (CR) is no longer necessary. Even in the case of relapses, most patients obtain a new remission as a result of therapy with ATO and ATRA, but an effective consolidation treatment is necessary to maintain it. The experience accumulated from studies published in the last two decades shows the effectiveness of hematopoietic stem cell transplantation (HSCT) in improving the outcome of patients who achieve a new CR. Thus, the expert groups recommend transplantation as consolidation therapy in patients with a second CR, with the indication for autologous HSCT in cases with molecular CR and for allogeneic HSCT in patients with the persistence of minimal residual disease (MRD) or with early relapse. However, there is a variety of controversial aspects related to the role of HSCT in APL, ranging from the fact that outcome data are obtained almost exclusively from retrospective studies and historical analyses to questions related to the type of transplantation, the impact of minimal residual disease, conditioning regimens, or the role of other therapeutic options. All these questions justify the need for controlled prospective studies in the following years.

Clinical impact of minimal residual disease in blood and bone marrow of children with acute myeloid leukemia.

The prognostic significance of bone marrow minimal residual disease (MRD) in pediatric patients with acute myeloid leukemia (AML) is well characterized, but the impact of blood MRD is not known. We, therefore, used flow cytometric assessment of leukemia-specific immunophenotypes to measure levels of MRD in both the blood and bone marrow of patients treated in the AML08 (NCT00703820) clinical trial. Blood samples were obtained on days 8 and 22 of therapy, whereas bone marrow samples were obtained on day 22. Among patients who tested as having MRD-negative bone marrow on day 22, neither day-8 nor day-22 blood MRD was significantly associated with the outcome. However, day-8 blood MRD was highly predictive of the outcome among patients who tested as having MRD-positive bone marrow on day 22. Although the measurement of blood MRD on day 8 cannot be used to identify patients who have day-22 MRD-negative bone marrow who are likely to relapse, our findings suggest that day-8 blood MRD results can identify patients with MRD-positive bone marrow who have a dismal prognosis and may be candidates for the early use of experimental therapy.

Impact of minimal residual disease standardised assessment by FDG-PET/CT in transplant-eligible patients with newly diagnosed multiple myeloma enrolled in the imaging sub-study of the FORTE trial.

18F-FDG-PET/CT is the current standard technique to define minimal residual disease (MRD) outside the bone marrow (BM) in multiple myeloma (MM), recently standardised applying the Deauville scores (DS) to focal lesions (FS) and bone marrow uptake (BMS) and defining the complete metabolic response (CMR) as uptake below the liver background (DS<4). In this analysis, we aimed at confirming the role of CMR, and complementarity with BM multiparameter flow cytometry (MFC) at 10-5, in an independent cohort of newly diagnosed transplant-eligible MM patients previously enrolled in the phase II randomised FORTE trial. 109 of the 474 global patients enrolled in the trial between February 23, 2015, and April 5, 2017, who had paired PET/CT (performed at baseline [B] and preceding maintenance therapy [PM]) and MFC evaluation, were included in this analysis. At B, 93% of patients had focal lesions within the bones (FS≥4 in 89%) and 99% increased BM uptake (BMS ≥4 in 61%). At PM, CMR was achieved in 63% of patients, which was a strong predictor for prolonged PFS in univariate analysis at landmark time PM (HR 0.40, P=0.0065) and in Cox multivariate analysis (HR 0.31, P=0.0023). Regarding OS, a trend in favour of CMR was present in univariate (HR 0.44, P=0.094), and Cox multivariate model (HR 0.17, P=0.0037). Patients achieving both PET/CT CMR and MFC negativity at PM showed significantly extended PFS in univariate (HR 0.45, P=0.020) and multivariate analysis (HR 0.41, P=0.015). We herein confirm the applicability and validity of DS criteria to define CMR and its prognostic relevance and complementarity with MFC at the BM level. Amgen, Celgene/Bristol Myers Squibb, Italian Ministry of Health (RC-2022-2773423).

Impact of minimal residual disease on relapse in childhood acute lymphoblastic leukemia: Lessons learnt from a tertiary cancer center in India

Prognostic predictive value of end of induction minimal residual disease (EOI-MRD) is well established in acute lymphoblastic leukemia (ALL). We evaluated the factors likely to affect EOI-MRD positivity (>0.01%) by flow cytometry and relapse in different BFM-95 (Berlin–Frankfurt–Munich) risk groups among children and adolescents. In this retrospective study, data of 223 newly diagnosed patients with ALL was analyzed. Association between demographic and pretreatment characteristics with EOI-MRD was assessed. Risk factors for relapse were analyzed using univariate and multivariate Cox regression. Proportion of the SR (standard risk), MR (moderate risk), and HR (high risk) patients was 18.8%, 60.9%, 20.3%, respectively. Positive EOI-MRD among these risk groups was observed in 11.9%, 18.3%, and 55.5% patients respectively (p value <.01%). MRD positivity was more likely to be associated with older age (>10 years) and BFM-HR patients (p value .0008 and <.0001). Thirty-four (15.2%) patients relapsed in the whole cohort. On univariate analysis, statistically significant factors for RFS (relapse-free survival) included hyperleukocytosis, high-risk cytogenetics, NCI (National Cancer Institute) high risk, poor day-8 prednisolone response, BFM–HR and positive EOI-MRD status. Of all these only EOI-MRD retained its impact by multivariate analysis. Positive EOI-MRD significantly predicted relapse in BFM-MR with 5-year RFS of 88.0% and 68.4% (p value .02). Five-year RFS of EOI-MRD negative and positive groups were 86.4% and 65.5%, respectively (p value .004). EOI-MRD is a powerful tool to predict relapse in children and adolescent with ALL especially in BFM-MR. Application of MRD in HR patients needs to be redefined in conjunction with other variables.

Impact of minimal residual disease on predicting outcomes in pediatric acute lymphoblastic leukemia; An Indian tertiary care centre study

Impact of minimal residual disease on predicting outcomes in pediatric acute lymphoblastic leukemia; An Indian tertiary care centre study

Clinical impact of minimal residual disease and genetic subtypes on the prognosis of childhood acute lymphoblastic leukemia.

This study analyzed data from two consecutive protocols for children newly diagnosed with acute lymphoblastic leukemia (ALL) to determine the clinical impact of minimal/measurable residual disease (MRD) and recently identified tumor genetic subtypes. Genetic subtypes were determined by sequential approaches including DNA indexing, reverse transcriptase-polymerase chain reaction, multiplex ligation-dependent probe amplification, and RNA-sequencing. MRD was assessed by flow cytometry. The Taiwan Pediatric Oncology Group TPOG-ALL-2013 study enrolled patients who received MRD-directed therapy. The 5-year event-free survival (EFS) and overall survival rates in the 2013 cohort were 77.8% and 86.9% compared to those of the 2002 cohort, which were 62.4% and 76.5%. Among patients treated with MRD-guided therapy, those with ETV6-RUNX1 fusion and high hyperdiploidy had the highest 5-year EFS (91.4% and 89.6%, respectively). The addition of dasatinib improved outcomes in patients with BCR-ABL1 ALL. Recently identified subtypes like DUX4-rearranged, ZNF384-rearranged, MEF2D-rearranged, and PAX5alt subtypes were frequently positive for MRD after remission induction, and these patients consequently received intensified chemotherapy. Treatment intensification according to the MRD improved the outcomes of patients presenting DUX4 rearrangements. In high-risk or very-high-risk subtypes, the TPOG-ALL-2013 regimen did not confer significant improvements compared to TPOG-ALL-2002, and the outcomes of BCR-ABL1-like, MEF2D-rearranged, and KMT2A-rearranged ALL subtypes (in addition to those of T-cell ALL) were not sufficiently good. Novel agents or approaches are needed to improve the outcomes for these patients. The TPOG-ALL-2013 study yielded outcomes superior to those of patients treated in the preceding TPOG-ALL-2002 study. This study provides important data to inform the design of future clinical trials in Taiwan. MRD-directed therapy improved the outcomes for pediatric ALL, especially standard-risk patients. Genomic analyses and MRD might be used together for risk-directed therapy of childhood ALL. Our work provides important data to inform the design of future clinical trials in Taiwan.

Conditioning Regimen Intensity and Donor Choice Do Not Impact Outcomes of Patients (pts) with Acute Myeloid Leukemia (AML) after Allogeneic Hematopoietic Cell Transplantation (Allo-HCT) in First Complete Remission (CR1): An EBMT Analysis

Allo-HCT is a curative treatment for fit pts with intermediate and adverse risk AML who achieve CR1. The presence of minimal residual disease (MRD) before allo-HCT has been shown to increase risk of relapse and decrease survival. Here, we describe outcomes of pts with AML who received allo-HCT in CR1 and the impact of MRD before allo-HCT on outcomes. We identified 1032 pts with AML who received allo-HCT in CR1 between 2015 and 2020 from the EBMT registry. The median age was 53.6 (range, 18.1-82.5) years and 526 (51%) were male. Most (94%) pts had de novo AML. FLT3-ITD and NPM1 mutations were detected in 46% and 44% of pts, respectively and high-risk cytogenetics were present in 20%. >1 course of induction therapy was required by 18% of pts to achieve CR1 and 39% were MRD positive at time of allo-HCT. The median time from diagnosis to allo-HCT was 4.9 months. Of pts with FTL3-wild type (FLT3-wt) disease, 33% were MRD negative and 22% were MRD positive at time of allo-HCT. In pts with FTL3-ITD mutation, 29% were MRD negative and 17% were MRD positive at time of allo-HCT. Donor type was matched sibling donor (MSD) in 29% of pts (n=297), matched unrelated donor (MUD) in 47% (n=481), mismatched unrelated donor (MMUD 9/10) in 8% (n=88), or haploidentical donor (haplo) in 16% (n=166). HCT-specific comorbidity index (HCT-CI) was >3 in 22% of pts (n=190). Myeloablative conditioning (MAC) was administered to 45% of pts (n=470), while reduced intensity conditioning (RIC) was used in 55% (n=562). The most common conditioning regimen was fludarabine/busulfan in MSD (n=148, 50%), MUD (n=272, 57%) and MMUD (n=38, 43%) recipients, while thiotepa/fludarabine/busulfan was the most used in haplo-HCT (n=99, 60%). Total body irradiation (TBI) was given to only 8% of pts (n=84), mainly in haplo-HCT (n=29). Most (n=1002, 98%) pts received calcineurin inhibitors (CNI), tacrolimus or cyclosporine A, for graft-versus-host disease (GVHD) prophylaxis in addition to mycophenolate mofetil (43%) or methotrexate (38%). Post-transplant cyclophosphamide was used in 18% (n=191) of pts, with 71% (n=136) having received haplo-HCT, and anti-thymocyte globulin was given to 67% (n=689). The median follow-up was 24 months. At day 60, the cumulative incidence of neutrophil engraftment was 99%. The cumulative incidence of grade III-IV acute GVHD (aGVHD) was 9% at day 180. At 2 years, the cumulative incidence of extensive chronic GVHD (cGVHD) was 17%. At 2 years, relapse incidence (RI), NRM, overall survival (OS), leukemia-free survival (LFS), and GVHD-free, relapse-free survival (GRFS) were 26%, 13%, 69%, 61%, and 48%, respectively. The main cause of death was primary disease in 55% of pts (n=157). Other causes of NRM were infections in 16% (n=45), and GVHD in 17% (n=47). In the multivariate analysis, compared to MSD, the use of MUD increased NRM (hazard ratio (HR) 1.86, p=0.02), GRFS (HR 1.28, p=0.039), aGVHD (HR 2.17, p<0.0001), and cGVHD (HR 1.36, p=0.044). The use of MMUD was associated with worse OS (HR 1.6, p=0.042) and higher risk of aGVHD (HR 2.11, p=0.003). Haplo-HCT was associated with higher incidence of aGVHD (HR 1.69, p=0.021) but lower risk of cGHVD (HR 0.63, p=0.033). Older age, lower performance status (PS), requiring >1 induction to achieve CR1, and FLT3-MRD positivity before allo-HCT were associated with worse LFS. Factors associated with lower OS were MMUD 9/10, older age, poor PS, >1 induction to achieve CR1, adverse cytogenetics, and FLT3-MRD positivity before transplant. In vivo TCD was associated with improved GRFS and lower risk of acute and cGVHD without increase of relapse. The use of RIC compared with MAC did not affect relapse, NRM or any other outcome. In conclusion, in pts with AML transplanted in CR1, those requiring >1 induction or with persistent FLT3-MRD positivity at time of allo-HCT had lower OS. Strategies to improve induction therapy, possibly through the addition of targeted agents, aiming to improve CR rates and deepening responses could potentially improve OS after allo-HCT. The use of RIC was associated with similar outcomes compared to MAC. This finding is particularly important for older pts or those with high HCT-CI scores unlikely to tolerate MAC. Survival after MSD allo-HCT is comparable to MUD and haplo, a finding that is in accordance with previous results for haplo and MUD as valid alternative donors in the absence of MSD. The use of MMUD was associated with lower OS compared to MSD and should be used as a last resort donor in this setting.

Combination of Cytogenetic Classification and MRD Status Correlates with Outcomes of Autologous Versus Allogeneic Stem Cell Transplantation in Adults with B Cell-Acute Lymphoblastic Leukemia in First Remission

Objectives: To analyze overall survival (OS), leukemia-free survival (LFS), cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) of patients with B cell-acute lymphoblastic leukemia (B-ALL) who received autologous or allogeneic stem cell transplantation and to provide the basis for the choice of transplantation method. Methods: We retrospectively investigated the outcomes of 388 adult patients with B-ALL in our center. The OS, LFS, CIR and NRM rate and the impact of minimal residual disease (MRD) within 3 chemotherapy cycles along with risk classification were explored. Results: Both univariate and multivariate analysis found that negative MRD within 3 chemotherapy cycles was the important factor associated with the prognosis. As to 355 patients who obtained first complete remission (CR1), we divided patients into 3 groups according to the risk stratification and MRD status within 3 chemotherapy cycles. For patients with negative MRD within 3 chemotherapy cycles and standard-risk group, the 3-year OS (82.5% vs 74.1%, P=0.364), LFS (74.5% vs 74.1%, P=0.904), CIR (25.5% vs 17.6%, P=0.648) and NRM rates(0% vs 8.3%, P=0.234) were not significantly different between autologous hematopoietic stem cell transplantation (auto-HSCT) and allogeneic hematopoietic stem cell transplantation (allo-HSCT) group（Figure 1）. In patients with negative MRD and high-risk factors, although auto-HSCT group and allo-HSCT group had similar 3-year OS(72.7% vs 68.5%, P=0.436) and LFS rate (62.8% vs 56.0%, P=0.375) , the lower NRM (1.5% vs 25.1%, P=0.000) was offset by higher CIR(35.7% vs 18.9%, P=0.018) in auto-HSCT group compared with allo-HSCT group（Figure 2）. As for other patients with high-risk factors and positive MRD after 3 chemotherapy cycles, the prognosis of auto-HSCT group was evidently worse than those of allo-HSCT group as there was a lower trend of 3-year OS (50.0% vs 66.0%, P=0.077), LFS rate (30.8% vs 47.1%, P=0.398) and significantly higher CIR rate(71.4% vs 39.1%, P=0.018) in auto-HSCT group compared to allo-HSCT group（Figure 3）. MRD within 3 chemotherapy cycles was also related to the selection of allogeneic transplantation methods and pretreatment schemes. The 3-year OS (67.4% vs 60.8% vs 65.2%, p=0.735), LFS (56.3% vs 48.3% vs 58.3%, P=0.538), CIR (21.7% vs 23.3% vs 13.3%, P=0.784) and NRM rate (22.1% vs 28.4% vs 28.3%, P=0.672) were similar in matched sibling donor hematopoietic stem cell transplantation (MSD-HSCT), haploid hematopoietic stem cell transplantation (haplo-HSCT) and unrelated donor hematopoietic stem cell transplantation (URD-HSCT) group patients who achieved negative MRD within 3 chemotherapy cycles. While MSD-HSCT group tended to have lower 3-year LFS (33.0% vs 54.1% vs 41.7%, P=0.198) and higher CIR rate (53.2% vs 33.7% vs 46.2%, P=0.233) when comparing with haplo-HSCT and URD-HSCT group patients whose MRD were still positive within 3 chemotherapy cycles. Moreover, in patients who achieved negative MRD within 3 chemotherapy cycles, there was no significant difference in 3-year CIR rate (24.5% vs 23.1%, P=0.784) between TBI group and non-TBI group, but the lower OS (64.2% vs 76.3%, P=0.027) and LFS (54.4% vs 71.3%, P=0.091) was mainly due to the higher NRM rate (17.8% vs 5.6%, P=0.062) in TBI group. For MRD positive patients, TBI group had advantages over non-TBI group, demonstrating a trend of higher 3-year OS (65.0% vs 42.9%, P=0.105), LFS (44.8% vs 27.1%, P=0.138), lower CIR (43.6% vs 63.8%, P=0.106) and similar NRM rate (11.7% vs 9.1%, P=0.671). In addition, we found that 8 most frequently mutated genes were KMT2D、FAT1、NRAS、PAX5、KRAS、SETD2、ASXL1、PTPN11 in 175 patients with preliminary second generation sequencing results（Figure 4）. Mutations in CARD11 and NOTCH signaling pathway were correlated with lower LFS (CARD11: 56.3% vs 16.7%, P=0.002; NOTCH signaling pathway: 59.2% vs 38.8%, P=0.049)（Figure 5）. Conclusions: Auto-HSCT with maintenance therapy after HSCT and non-TBI pretreatment schemes appears to be an attractive treatment option for patients with B-ALL especially for those who achieved negative MRD within 3 chemotherapy cycles. For MRD positive patients, allogeneic transplantation and TBI pretreatment schemes may be more effective. Key words: auto-HSCT, allo-HSCT, acute lymphoblastic leukemia, minimal residual disease Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Analysis of Single Cell Transcriptomics in Paired Pediatric T-ALL Samples Collected at Diagnosis and Following End of Induction Therapy Reveals an MRD-Associated Stem Cell Signature

IntroductionDespite recent improvement in outcomes for de novo disease, pediatric T-cell acute lymphoblastic leukemia (T-ALL) remains challenging to treat at relapse. Investigation into genomic markers of treatment response and therapy resistance offers an opportunity to further enhance outcomes for these patients. We previously identified a T-ALL blast-associated gene signature at diagnosis (Dx) and characterized the immune microenvironment in Dx T-ALL marrow samples using single cell transcriptome analysis (Bhasin et al. Blood 2020(ASH)). This approach allowed us to generate a granular expression map of both the T-ALL landscape and the Dx bone marrow (BM) immune microenvironment. Here we expand this work by evaluating samples collected from the same patients Dx and End of Induction (EOI) BM samples from pediatric T-ALL patients. The use of paired samples provides insight into treatment-induced changes in the microenvironment. Further, the inclusion of both minimal residual disease (MRD) positive and MRD negative samples allowed us to compare differences between these groups.MethodsUsing the 10X genomics platform, we profiled the single cell transcriptome of ~18,000 BM and immune microenvironment cells from viably frozen samples collected from T-ALL patients at Dx or EOI. Five paired Dx and EOI samples and one EOI sample from a patient with relapsed T-ALL were evaluated, for a total of 11 samples. Three paired samples were MRD positive at EOI and two were MRD negative; the relapsed sample was MRD negative. Cell clustering was performed using the Seurat package and differential expression analysis was performed using R/Bioconductor packages (Hao et al. Cell 2021). Cell communication analysis was conducted using the CellChat R tool (v 1.0.0) to infer cell-cell communication within the EOI MRD positive and MRD negative subsets and compare their communication networks (Jin et al. Nature Comm 2021).ResultsUsing our previously described blast-associated gene signature (Bhasin et al. ASH 2020) we were able to identify residual blast populations at EOI in MRD-positive samples. Comparative analysis of gene profiles at Dx and EOI showed significant changes in the microenvironment cell populations with highest increase in erythroid cell populations after induction therapy. The gene expression profiles were significantly different for immune cells at Dx and EOI and the relapsed sample had greater similarity to the Dx samples indicating a persistent immunosuppressive environment. Clustering analysis of the EOI samples (3 MRD positive and 2 MRD negative) demonstrated the presence of patient specific blast cells in MRD positive samples that retained patient-specific transcriptomeheterogeneity at EOI (Fig.1A). Analysis of communication networks between different cell types based on receptor and ligand expression levels between different cell types identified a CD34 + cluster of stem cells that had different interactions with other immune populations in the MRD positive and negative subsets. Differential expression analysis between the MRD positive and MRD negative cells in this CD34 + stem cell cluster identified higher expression of myeloid associated genes such as CEBPB, CEBPD, AZU1 in the MRD negative group relative to the MRD positive cells, which showed higher expression of B-cell related genes such as IGHM, VPREB1, CD79A/ B along with upregulation of P13K signaling in B-lymphocytes, B-cell receptor signaling and autophagy pathways. Analysis of upstream regulators based on the differential gene signature between the MRD positive and MRD negative group demonstrated upregulation of MYC and TCF3 activity and inhibition of TGFB1, CSF3 and CEBPA in MRD positive compared to MRD negative samples (Fig.1B).Conclusions: Leukemic blasts exhibit patient-specific gene expression signatures that are present at EOI in MRD positive samples. Exploration of the impact of minimal residual disease at EOI revealed differential gene expression patterns in stem cells from MRD positive samples, characterized by activation of B cell related signaling pathways and regulators such as MYC and TCF3. In contrast, a more myeloid-like expression signature was observed in stem cells from MRD negative samples. These findings open the avenues for exploration of therapeutic targets of T-ALL progression. [Display omitted] DisclosuresDeRyckere: Meryx: Other: Equity ownership. Graham: Meryx: Membership on an entity's Board of Directors or advisory committees, Other: Equity ownership.

Recent Progress in Interferon Therapy for Myeloid Malignancies.

Myeloid malignancies are a heterogeneous group of clonal haematopoietic disorders, caused by abnormalities in haematopoietic stem cells (HSCs) and myeloid progenitor cells that originate in the bone marrow niche. Each of these disorders are unique and present their own challenges with regards to treatment. Acute myeloid leukaemia (AML) is considered the most aggressive myeloid malignancy, only potentially curable with intensive cytotoxic chemotherapy with or without allogeneic haematopoietic stem cell transplantation. In comparison, patients diagnosed with chronic myeloid leukaemia (CML) and treated with tyrosine kinase inhibitors (TKIs) have a high rate of long-term survival. However, drug resistance and relapse are major issues in both these diseases. A growing body of evidence suggests that Interferons (IFNs) may be a useful therapy for myeloid malignancies, particularly in circumstances where patients are resistant to existing front-line therapies and have risk of relapse following haematopoietic stem cell transplant. IFNs are a major class of cytokines which are known to play an integral role in the non-specific immune response. IFN therapy has potential as a combination therapy in AML patients to reduce the impact of minimal residual disease on relapse. Alongside this, IFNs can potentially sensitize leukaemic cells to TKIs in resistant CML patients. There is evidence also that IFNs have a therapeutic role in myeloproliferative neoplasms (MPNs) such as polycythaemia vera (PV) and primary myelofibrosis (PMF), where they can restore polyclonality in patients. Novel formulations have improved the clinical effectiveness of IFNs. Low dose pegylated IFN formulations improve pharmacokinetics and improve patient tolerance to therapies, thereby minimizing the risk of haematological toxicities. Herein, we will discuss recent developments and the current understanding of the molecular and clinical implications of Type I IFNs for the treatment of myeloid malignancies.

Evaluation of the Impact of Minimal Residual Disease, FLT3 Allelic Ratio, and FLT3 Mutation Status on Overall Survival in FLT3 Mutation-Positive Patients with Relapsed/Refractory (R/R) Acute Myeloid Leukemia (AML) in the Chrysalis Phase 1/2 Study

Evaluation of the Impact of Minimal Residual Disease, FLT3 Allelic Ratio, and FLT3 Mutation Status on Overall Survival in FLT3 Mutation-Positive Patients with Relapsed/Refractory (R/R) Acute Myeloid Leukemia (AML) in the Chrysalis Phase 1/2 Study

Outcomes of Stratification to ASCT or Not Based on Depth of Response: Results of a Phase 2 Trial Assessing the Impact of Minimal Residual Disease (MRD) in Multiple Myeloma Patients with Deferred ASCT (PADIMAC)

Introduction: The role of autologous stem cell transplantation (ASCT) as first-line therapy for newly diagnosed transplant eligible (NDTE) patients with multiple myeloma remains under evaluation. The primary objective of this study was to evaluate the progression-free survival (PFS) according to MRD status of patients achieving ≥VGPR following induction therapy followed by no further treatment. Those who achieved PR proceeded to ASCT. PADIMAC (ISRCTN no: 03381785) was designed to provide baseline data for a future response-adapted therapy trial in NDTE patients. Methods: This single arm phase 2 trial was conducted at 13 UK sites. Patients eligible for ASCT received PAD (bortezomib (BZ), doxorubicin and dexamethasone) for 4-6 cycles. Those achieving The overall response rate to PAD was 82%, 27 patients came off study prior to PBSCH (17 stable disease, 8 progressive disease (PD), 1 died, 1 withdrew). 19 patients came off study post-PBSCH (7 PD, 6 toxicities, 1 allograft, 5 withdrawal for other reasons). 63 (41%) patients achieved ≥VGPR post PBSCH, and 44 (29%) patients achieved PR of whom 36 proceeded to ASCT. After a median follow-up of 47.5m, median PFS for VGPR-WW and 15 (24%) patients remain alive and progression-free for >24m. Patients who were MRD neg at d100 (n=18) had a median PFS of 25.7m vs 9.5m for MRD pos (n=32), 13 missing. For PR-ASCT, the median PFS was 20.3m (95% CI: 19.7-20.9); 16.8m for MRD pos (n=20), whilst only 7 were MRD neg at day 100 (missing=5). Overall, MRD status at day 100 correlated with PFS (MRD neg: 25.7m vs MRD pos: 15.6m, p Conclusions: This is the first trial to investigate the outcomes of patients who achieve ≥VGPR following up to 6 cycles of induction therapy and receive no further treatment. Patients who were MRD pos at day 100 had a particularly poor outcome (median PFS of 9.5m) as did those with adverse cytogenetics (14.4 months), signifying the need for further treatment. However, those who were MRD neg at day 100 had a longer median PFS of 25.7m, which was similar to the median PFS of the PR-ASCT group. MRD status at day 100 post PBSCH was associated with PFS irrespective of treatment. These data support designing response adapted trials according to MRD status rather than serological response. Disclosures Popat: Celgene: Honoraria, Other: Travel support for meetings; Amgen: Honoraria; Takeda: Honoraria, Other: Travel support for meetings; Janssen: Honoraria, Other: Travel support for meetings. Cavenagh: Janssen: Honoraria; Celgene: Consultancy; Novartis: Consultancy; Takeda: Consultancy. Streetly: Janssen-Cilag Pharma: Speakers Bureau. D9Sa: Janssen Cilag: Consultancy, Honoraria, Other: Education grant, Research Funding; Amgen: Consultancy, Honoraria, Research Funding. Cook: Celgene: Honoraria, Other: Travel support, Research Funding; Janssen: Honoraria, Other: Travel support, Research Funding; Myeloma UK: Membership on an entity9s Board of Directors or advisory committees; Amgen: Honoraria, Other: Travel support; Takeda: Honoraria; Jazz Pharmaceuticals: Honoraria. Rabin: Celgene: Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Takeda: Consultancy, Other: Travel support for meetings, Speakers Bureau; Janssen: Consultancy, Other: Travel support for meetings, Speakers Bureau; Amgen: Consultancy, Speakers Bureau. Owen: Takeda: Honoraria, Other: travel support; Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Other: travel support. Yong: Janssen: Honoraria, Research Funding; Amgen: Honoraria, Research Funding.

The Prognostic Impact of Minimal Residual Disease on Risk of Progression and Progression Free Survival in Acute Myeloid Leukemia

Assessment of minimal residual disease (MRD) in patients with complete remission CR) defined as <5% bone marrow blast count at allogeneic stem cell transplantation (HSCT) provides powerful independent prognostic information in acute myeloid leukemia and defines risk groups for transplant outcomes. Previous studies showed that transplant outcomes for AML patients with morphologically detectable disease (active disease) are comparable to those for CR patients with MRD (CR-MRDpos).We aimed to compare the outcomes of 458 AML patients who underwent HSCT after 2012 at our institution based on the status of morphologically detectable disease and MRD by 8 color flow cytometry at HSCT in addition to cytogenetic and molecular risk classification by European LeukemiaNet. The primary outcomes were disease progression and progression free survival (PFS) and analyses were stratified by ELN risk classification as favorable and intermediate (n=295) and adverse (n=163).Patients were categorized as active disease (n=81) vs. CR-MRDneg (n=191) and CR-MRDpos (n=52) vs. primary induction failure with marrow aplasia (PIF)-MRD (n=25) and PIF-MRDpos (n=74) vs. relapsed refractory with marrow aplasia (RR)-MRDneg (n=19) and RR-MRDpos (n=16). Median age of cohort was 56 (range, 3-80). Conditioning intensity was either myeloablative (n=260) or reduced intensity (n=198).The median follow-up of survivors was 18 months. For disease progression in favorable/intermediate risk by ELN, the only prognostic factors were the morphological disease status and MRD as shown in Figure 1. Active disease patients had the highest incidence of progression at 2-year with 53% which was similar to 43% observed in RR patients (HR=0.6, p=0.3). In comparison to active disease, CR-MRDpos and PIF-MRDpos patients had lower incidence of progression with 29% and 32% at 2-yr (HR=0.5, p=0.08 and HR=0.5, p=0.06). Among adverse risk patients, CR patients had significantly lower risk of disease progression independent of their MRD status when compared with active disease patients (HR=0.4, p=0.002 for CR-MRDneg and HR=0.4, p=0.02 for CRMRDpos).For PFS at 2 year, not only morphological disease status and MRD but also older age and hematopoietic comorbidity index (HCT-CI) were prognostic. In patients with favorable/intermediate ELN risk, Classification and Regression Tree multivariate analysis revealed 3 potential PFS groups: high PFS group included CR-MRDneg patients aged <60 who had the best 2-yr PFS estimated at 81%, and CR-MRDneg but aged ≥60 who had an estimated 2-yr PFS of 61%. In contrast, low PFS group included not CR-MRDneg patients with HCT-CI ≥4 in combination with either RR-marrow aplasia (2-yr PFS 0%) or age >60 (2-yr PFS 10%). In the absence of RR-marrow aplasia and older age, not CR-MRDneg patients with HCT-CI ≥4 had an intermediate 2-yr PFS (30%) which was comparable to the PFS (43%) in not CR-MRDneg patient with HCT-CI <4, irrespective of age.For adverse ELN risk group, PFS was the best in patients with CR (independent of the MRD status) and HCT-CI <4 with 2 year PFS of 59%. All other adverse risk patients had similarly low PFS with estimates of 17%-23%.In conclusion, we observed a lower progression incidence in CRMRDpos patients compared with active disease in both intermediate and adverse risk ELN groups after HSCT. However, PFS is a more complex endpoint with not only morphological disease status and MRD but also ELN risk classification, older age and HCT-CI determining the outcome expectations. These factors need to be taken into account when planning treatment for HSCT and thereafter. [Display omitted] DisclosuresOran:Celgene: Research Funding; AROG: Research Funding; Astex: Research Funding.

Immune Recovery Refines the Prognostic Impact of Minimal Residual Disease on Overall and Progression Free Survivals after Frontline Fludarabine, Cyclophosphamide and Rituximab (FCR) in CLL Patients

Introduction: in chronic lymphocytic leukemia (CLL), treatment with FCR is the standard of care for treatment-naive and fit enough patients (pts). MRD threshold assessed 3 months after end of treatment (EOT) is considered as a surrogate for both progression free survival (PFS) and overall survival (OS). On the other hand, antibiotic prophylaxis is often started and maintained until CD4>200/mm3. We hypothesized that a monitoring of MRD versus normal immune cells recovery kinetics during follow-up (FU) could help refine the predictive power of MRD EOT evaluation, and allow identification of patients with increased risk of either infection and/or relapse.Methods: we prospectively collected fresh peripheral blood (PB) samples of 162 pts from 2 institutions in France (2006-2017) at the end of treatment (EOT), then every 6 months until month 24 (M24). We used 4-color flow cytometry to quantify both MRD (classified as 3 clusters: low (<10-4), intermediate (≥10-4 but <10-2) or high (≥10-2) level) and the reconstitution of normal lymphocyte subsets (CD4, CD8, NK). We plotted survival curves using Kaplan-Meier method and landmark analyses at different time points (9-15-21 months from day 1 cycle 1 FCR). Cox proportional model with time-dependent covariates (MRD, CD4, CD8 and NK counts) was also used to evaluate the correlation of covariates with outcomes.Results: one hundred and sixty-two pts (69% male, median age 58y) received a median of 6 courses of FCR. IGHV was mutated in 36.6%, and del13q was the most frequent cytogenetic abnormality (37.4%). Only 7 pts had del17p and/or mutation of TP53. After a median follow-up of 60.5 months, 46.3 % of pts have relapsed and/or died (median PFS estimation: 65.7 months, median OS not reached). At EOT, 65.3%, 27.2% and 7.5 % of pts achieved low, intermediate and high MRD respectively; 64.2% of pts had CD4≤200/mm3 while 35.8% had CD4>200/mm3.At landmark analysis of EOT, multivariate Cox model identified IgHV unmutated (HR 2.46), MRD intermediate (HR 3.3) or high (HR 19.57) (Figure 1), CD4 level (HR 1.22) as factors associated with PFS, and only MRD (HR 1.1) and CD4 counts (HR 1.2) were found to be associated with improved OS (Figure 2). In EOT intermediate MRD pts (n=34), those having EOT CD4≤200/mm3 had better 5-year PFS than those having CD4>200/mm3 (53.5% vs 7.7%, p=0.001) (Figure 3). This difference was not significant for low MRD pts (65% vs 58.9%, p=0.7). In landmark analysis at 21 months (=one year after EOT assessment), intermediate MRD pts (n=44) having CD4≤200/mm3 had significantly better 5-year PFS (85.7% vs 52.8%, p=0.0138). When performing successive landmark analyses on the whole population, CD4>200/mm3 was associated with worse 5-year PFS at EOT (34.1% vs 59.6%, p=0.016), 6 months (49.5% vs 58.8%, p=0.017) and 12 months (46.7% vs 68.3%, p=0.008) (Figure 4). In total, 20.4% of patients developed opportunistic infections, not correlated to CD4/CD8/NK counts.Conclusion: complementarily with MRD, CD4 count is an independent predictive factor of PFS and OS after FCR. As expected, MRD increase during FU is independently associated with worse PFS and OS, but CD4 counts at EOT and the first year post-FCR refine prognosis of the “MRD detectable” risk group (independently of CLL associated risk factors such as del17p/IgHV status). This is important in the interpretation and design of clinical trials dedicated to prolong PFS/OS using consolidation regimens based on MRD detection>10-4 in CLL. On the other hand, CD4>200/mm3 was not predictive of infectious events. [Display omitted] DisclosuresRecher:Celgene, Sunesis, Amgen, Novartis: Research Funding; Novartis, Celgene, Jazz, Sunesis, Amgen: Consultancy. Ysebaert:Janssen: Consultancy, Research Funding, Speakers Bureau.

Prognostic impact of minimal residual disease at the end of consolidation in NCI standard-risk B-lymphoblastic leukemia: A report from the Children's Oncology Group.

The 5-year disease-free survival (DFS) of National Cancer Institute (NCI) high-risk (HR) B-lymphoblastic leukemia (B-ALL) patients with end of induction (EOI) minimal residual disease (MRD) ≥0.1% and end of consolidation (EOC) MRD ≥0.01% is 39 ± 7%, warranting consideration of hematopoietic stem cell transplant (HSCT). However, the impact of EOC MRD in NCI standard-risk (SR) B-ALL patients using COG regimens is unknown. We found that SR patients with MRD ≥0.01% at both EOI and EOC have a 4-year DFS/overall survival (OS) of 72.9 ± 19.0%/91.7 ± 10.8% versus 90.7 ± 2.9%/95.5 ± 2.0% (p=.0019/.25) for those with EOI MRD ≥0.01% and EOC MRD <0.01%. These data suggest that routine use of HSCT may not be warranted in EOC MRD ≥0.01% SR patients.

Impact of pre-transplantation minimal residual disease (MRD) on the outcome of Allogeneic hematopoietic stem cell transplantation for acute leukemia

ABSTRACT Objective To investigate the impact of minimal residual disease (MRD) before allogeneic hematopoietic stem cell transplantation (allo-HSCT) on the outcome of acute leukemia. Methods Data from 114 patients who were diagnosed with acute leukemia (AL) and underwent allo-HSCT between Jan 2013 and Dec 2019 were collected and analyzed. The patients were attributed into MRD positive (MRD+) group and MRD negative (MRD−) group. Results Among the 114 acute leukemia patients, there were 32 MRD+ patients before transplantation, and 82 MRD− patients. No significant difference was found between the MRD+ group and the MRD− group in the incidence of acute graft-versus-host disease (aGvHD) (p = 0.09). Compared with the MRD+ group, the MRD− group had a higher incidence of chronic graft-versus-host disease (cGvHD) (p = 0.008). There is no significance in relapse between the two groups (p = 0.084), while the incidence of relapse was seemingly higher in the MRD+ group: 36.9% Vs 19.7% . We attributed to the lack of sample size and NRM in MRD+ group was remarkably higher. The MRD+ group had significantly worse one-year overall survival (OS) ( , p = 0.003) and one-year progression-free survival (PFS) (, p = 0.009). In the multivariate analysis, MRD+ was an independent prognostic factor for OS (HR = 1.898; 95%CI 1.042–3.457; p = 0.036). Conclusion Pre-transplantation MRD positive status is a risk factor for survival and prognosis after HSCT. Upon this, emphasis should be put on (1) screening more efficient chemo regimen with targeted agents, to help patients reach and keep MRD− status before transplantation; (2) designing better management with different GvHD prophylaxis treatment, timely disease monitoring and preemptive intervention on relapse.

Impact of Minimal Residual Disease and Chimerism Monitoring at Different Timepoints after Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia

¶ Martin-Rojas RM and Oarbeascoa G contributed equally to this work. INTRODUCTION Relapse is the main cause of treatment failure after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acute myeloid leukemia (AML). The evaluation of minimal residual disease (MRD) could provide a more accurate assessment of the depth of response, and therefore identify patients with higher risk of relapse. AIMS The aim of our study was to analyze the impact of pre-HSCT flow cytometry (FCM) and molecular MRD together with chimerism and MRD in the early post-HSCT period in patients with AML. METHODS We conducted a retrospective study in patients with complete remission AML who underwent a HSCT between 2008 and 2019 in our center. MRD was analyzed by flow cytometry in bone marrow aspirates and by quantitative RT-PCR (NMP1, RUNX1-RUNX1T1, CBFB-MYH11, KMT2A-MLLT3, WT1) in bone marrow aspirates and/or peripheral blood. MRD was determined within the 30 days preceding the HSCT and at day +30 and +90 post-HSCT. Bone marrow and selected CD34+ lineage chimerism was analyzed by STR (AmpFISTR SGM Plus, Thermo Fisher) at days +30 and +90 post-HSCT. This study was approved by our Institutional Ethics Committee. Data were analyzed using IBM SPSS Statistics version 24 and R version 3.5.1. RESULTS A total of 115 patients were analyzed. Pre-HSCT MRD was negative in 58 patients (50.4%) and positive in 57 patients (49.6%). We found no statistically significant differences in the characteristics between the two groups (Table 1). Median follow up was 39 months (IQR 10.4-55.8). 3-year overall survival (OS) for patients with pre-HSCT negative MRD was 72.5% versus 70.3% in patients with positive MRD (p=0.41), with an event free survival (EFS) of 66.9% versus 66.1 (p=0.48) respectively (Figure 1). Median time to the beginning of immunosuppression withdrawal was 82.5 days (IQR 59-93) for patients with negative MRD and 68 days (IQR 55.3-85.3) for patients with positive MRD (p&amp;lt;0.001). The cumulative incidence of grade II-IV acute graft versus host disease (aGVHD) and moderate-severe chronic GVHD did not show statistically significant differences based on the MRD status. Similarly, the cumulative incidence of relapse and the 2-year mortality was not significantly different between the two groups. Patients with negative MRD at day +30 showed a 2-year OS of 83.5% versus 58.1% in patients with positive MRD (p=0.03) and a EFS of 79.9% versus 48.6% (Figure 2). The cumulative incidence of relapse was more elevated in patients with positive MRD (29.8% versus 13.6%) at day +30. Patients with mixed chimerism (MC) at day +30 showed a significantly lower 3-year OS and EFS than patients with complete chimerism (CC). Likewise, the cumulative incidence of relapse was significantly higher in patients with MC, both if detected in bone marrow aspirate and in CD34+ cells. The multivariate analysis revealed that MRD status at day +30 post-HSCT was an independent prognostic factor for EFS (HR 3.74; 95% CI 1.38-10.1; p=0.009). CONCLUSIONS Patients with AML presenting a positive MRD in the early post-HSCT period and those who show a MC at day +30 post-HSCT have lower EFS, with positive MRD at day +30 being an independent prognostic factor for EFS. The evaluation of MRD and chimerism in the early post-HSCT period is useful to identify patients with higher risk of relapse, who may take advantage of preemptive measures. Disclosures Kwon: Gilead, Novartis, Pfizer, Jazz: Consultancy, Honoraria.

Outcomes with Sequential FLT3-Inhibitor (FLT3i) Based Therapies in Patients (pts) with FLT3-Mutated Acute Myeloid Leukemia (AML) Exposed to Prior FLT3i Based Therapies

Outcomes with Sequential FLT3-Inhibitor (FLT3i) Based Therapies in Patients (pts) with FLT3-Mutated Acute Myeloid Leukemia (AML) Exposed to Prior FLT3i Based Therapies