Value Of Minimal Residual Disease Research Articles

Long-Term Outcome of Relapsed Acute T-Lymphoblastic Leukemia (T-ALL) in Children and Adolescents

Introduction Despite improvements in first-line treatment of childhood T-ALL, relapse remains the main cause of treatment failure. Patients with T-ALL experiencing leukemia recurrence have a dismal outcome, mostly due to a failure to achieve a second complete remission (CR) or to subsequent relapse. Assessment of minimal residual disease (MRD) may allow identifying subsets of patients with different prognosis. We analyzed the outcomes of 141 Italian children and adolescents who experienced T-ALL relapse after frontline multicenter AIEOP-BFM ALL treatment trials. Methods: This retrospective study aimed at describing the outcomes of Italian patients with T-ALL who were enrolled in the AIEOP-BFM ALL2000, 2006 and 2009 trials and subsequently experienced disease relapse. Among the 750 T-ALL Italian patients enrolled in the above-mentioned trials, 141 had a disease recurrence (70/251 patients in ALL2000 trial, 29/190 in ALL2006 trial, and 42/309 in ALL2009 trial). Molecular MRD monitoring after induction therapy for leukemia relapse was available for 38 patients. Results: The 141 patients, 113 males and 28 females, had a median age of 9 years at diagnosis (range 1-17) and 10 at relapse (range 2-19). At diagnosis, 7 patients were allocated to the Standard (SR), 45 to the Medium (MR), and 89 to the High Risk (HR) group, respectively. Thirty-four (4 MR and 30 HR patients) of these children were given allogeneic hematopoietic stem cell transplantation (allo-HSCT) in 1st CR and 41 had received central nervous system (CNS) radiotherapy. Relapses were classified as very early (occurring <18 months from diagnosis), early (occurring ≥18 months from diagnosis and <6 months after completion of primary therapy), and late (occurring >6 months after the end of the frontline protocol) in 92, 36, and 13 patients, respectively. Site of relapse was isolated bone marrow (BM) in 74 patients, combined BM/extramedullary (EM) in 23 patients, and isolated EM in 44 patients (involving a single EM site in 37 cases and >1 EM site in 7 cases; CNS was involved in 29 patients). At the time of relapse, 7 patients were treated according to AIEOP ALL REC98 Trial, 57 according to AIEOP ALL REC2003 Trial, while the remaining 77 patients received other combination of chemotherapy. After reinduction/consolidation treatment, 58 patients were given allo-HSCT from either a matched family donor (16) or an unrelated donor (UD, 31 patients, of which 21 from a matched UD and 10 from a mismatched UD) or an HLA-partially matched relative (11). With a median follow-up of 7.5 years (range 2-14), 34 patients are currently alive; 17 of these patients had EM isolated relapse, which was very early in 13 cases, and 17 had BM involvement at relapse, with late relapse in 8 cases. The 8-year overall survival (OS) of the whole cohort was 23.3% (95% CI 16.5-30.7) (Figure 1A). Isolate EM relapse (Figure 1B) and late relapses were associated with a better OS probability. Both factors remained statistically significant in multivariable analysis. Moreover, in univariable analysis a better prognosis was observed in patients treated more recently (i.e., after year 2008) (8-year OS 31.8% vs 16.2%, p=0.01). After allo-HSCT, 29 patients are currently alive, while the remaining 29 patients died from progressive disease (21) or transplant-related causes (8), leading to a 8-year OS for patients given allo-HSCT in 2nd RC of 48.5% (95% CI 34.7-61.0). Of the 83 children given sole chemotherapy, 5 are currently alive, while the remaining 78 died due to progressive disease (53), organ-failure (7), infection (9), or other causes (9). MRD monitoring was performed for 38/97 patients with BM involvement (5 with late, 13 with early, and 20 with very early relapse, respectively). Patients with a post-induction MRD <10-3 showed a reduced incidence of relapse (Figure 1C), resulting into better probability of 8-year OS (Figure 1D) in comparison to patients with higher MRD levels. Conclusions: Our results confirm that T-ALL relapse, especially if involving BM and occurring within 6 months from treatment discontinuation is still associated with poor prognosis, although in the last 10 years a higher proportion of children with relapsed T-ALL has been rescued by second line therapy, including transplantation. In this Italian retrospective cohort, a MRD value >10-3 at the end of induction therapy predicts a miserable outcome, this finding allowing to identify patients eligible to experimental therapies. Figure 1 Disclosures Merli: Novartis: Honoraria; Amgen: Honoraria; Bellicum: Consultancy; Sobi: Consultancy. Rizzari:JazzPharma, Shire, medac , Sigma-Tau, Baxalta, Shire and Servier: Consultancy, Honoraria; Together with study group from Shire, medac , Sigma-Tau, Baxalta, Shire and Servier: Research Funding. Parasole:Servier: Honoraria; Baxalta: Honoraria; Eusapharma: Honoraria. Locatelli:bluebird bio: Consultancy; Miltenyi: Honoraria; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Monitoring for Minimal Residual Disease before and after Allogeneic Hematopoietic Stem Cell Transplantation in Newly Diagnosed Acute Leukemia

Objective:To assess the relevance between minimal residual disease (MRD) levels and disease recurrence and prognosis in patients with acute leukemia before and after hematopoietic stem cell transplantation (HSCT), and further to explore potential benefit based on pre-transplant MRD stratification. Methods: A total of 113 patients with newly diagnosed acute leukemia in Fujian Union hospital from April 2013 to April 2019 were retrospectively analyzed. 94 patients were complete remission (CR)( 50 cases of AML and 44 cases of ALL). 19 patients didn't achieve CR( 10 patients with AML and 9 patients with ALL). The median age was 26(1-56) years. 67 patients were male and 46 patients were female. The sources of hematopoietic stem cell include bone marrow, cord blood and peripheral blood stem cell. All patients underwent myeloablative conditioning before transplantation. Standard graft-versus-host disease (GVHD) prophylaxis was applied in all patients. MRD was measured by flow cytometry and real-time quantitative polymerase chain reaction(PCR). MRD values >10-4 or BCR-ABL were considered positive for minimal residual disease and compared with bone marrow morphological findings. Median follow time was 15.2 (2.2 to 70.5) months. Results: Among patients in CR, achieving pre-MRD negativity was associated with longer 2-year relapse-free survival (2-year RFS; 81.4% vs 49.1%; P=0.003) and 2-year overall survival (2-year OS; 84% vs 50.6%; P=0.012). Compared to pre-MRDneg patients, pre-MRDpos patients had a higher incidence of relapse (31.2% vs. 5.1%, P=0.001). There was no significant difference between OS and MRD level after transplantation (OS; post-MRDneg 82.9% vs. post-MRDpos 66.7%, P =0.468). In the second set of analyses, CR patients were classified into the MRDpos /MRDpos group, the MRDpos /MRDneg group, the MRDneg /MRDpos group, and the MRDneg /MRDneg group according to MRD dynamics. Compared to the other three groups, patients from the MRDpos /MRDpos group had higher cumulative incidences of relapse (MRDpos /MRDpos, 48.3%; MRDpos /MRDneg, 22.2%, MRDneg /MRDpos,40.0%; MRDneg /MRDneg, 2.7%; P<0.000) and worse 2-year RFS(MRDpos /MRDpos, 34.3%; MRDpos /MRDneg, 60.0%, MRDneg /MRDpos,60.0%; MRDneg /MRDneg, 76.6%; P=0.012). 1-year RFS and 1-year OS were similar in patients who didn't achieve CR, regardless of the post-MRD response(1-year RFS; 50.0% vs. 14.3%, P=0.063 and 1-year OS; 50.0% vs. 14.3%, P=0.184).In this group, 7 patients with MRD-positive after transplantation did not survive, but 12 post-HSCT MRD-negative patients had not relapsed. Conclusion: MRD can be used as a sensitive indicator to evaluate disease prognosis. Patients who are in morphologic remission and have no evidence of MRD before the HSCT come to encouraging leukemia-free survival. Continuous regular dynamic observation is important for guiding disease recurrence and prognosis. Disclosures No relevant conflicts of interest to declare.

More precisely defining risk peri-HCT in pediatric ALL: pre- vs post-MRD measures, serial positivity, and risk modeling

AbstractDetection of minimal residual disease (MRD) pre– and post–hematopoietic cell transplantation (HCT) for pediatric acute lymphoblastic leukemia (ALL) has been associated with relapse and poor survival. Published studies have had insufficient numbers to: (1) compare the prognostic value of pre-HCT and post-HCT MRD; (2) determine clinical factors post-HCT associated with better outcomes in MRD+ patients; and (3) use MRD and other clinical factors to develop and validate a prognostic model for relapse in pediatric patients with ALL who undergo allogeneic HCT. To address these issues, we assembled an international database including sibling (n = 191), unrelated (n = 259), mismatched (n = 56), and cord blood (n = 110) grafts given after myeloablative conditioning. Although high and very high MRD pre-HCT were significant predictors in univariate analysis, with bivariate analysis using MRD pre-HCT and post-HCT, MRD pre-HCT at any level was less predictive than even low-level MRD post-HCT. Patients with MRD pre-HCT must become MRD low/negative at 1 to 2 months and negative within 3 to 6 months after HCT for successful therapy. Factors associated with improved outcome of patients with detectable MRD post-HCT included acute graft-versus-host disease. We derived a risk score with an MRD cohort from Europe, North America, and Australia using negative predictive characteristics (late disease status, non–total body irradiation regimen, and MRD [high, very high]) defining good, intermediate, and poor risk groups with 2-year cumulative incidences of relapse of 21%, 38%, and 47%, respectively. We validated the score in a second, more contemporaneous cohort and noted 2-year cumulative incidences of relapse of 13%, 26%, and 47% (P < .001) for the defined risk groups.

The Value of Minimal Residual Disease as a Progression-Free Survival Predictor After Autologous Hematopoietic Stem Cell Transplantation in Multiple Myeloma Patients

The Value of Minimal Residual Disease as a Progression-Free Survival Predictor After Autologous Hematopoietic Stem Cell Transplantation in Multiple Myeloma Patients

Influence of value of minimal residual disease at risk of developing recurrence of relapse in patients with acute lymphoblastic leukemia

Minimal residual disease (MRD) is the most significant predictor of the relapse in patients with acute lymphoblastic leukemia (ALL). MRD evaluation is necessary not only for the prediction of the relapse, but for additional stratification of patients by the risk groups in order to address the issue of the therapy individualization and to evaluate the therapy quality. This study analyzes the MRD parameters in patients with ALL at the stage of induction therapy and evaluates the effect of the value of the minimum residual disease on survival rates and the risk of relapse in patients with ALL treated according to protocol ALL-MB 2008.

Imaging and bone marrow assessments improve minimal residual disease prediction in multiple myeloma.

The value of minimal residual disease (MRD) status by bone marrow and imaging analysis as independent prognostic factors has been well established in multiple myeloma (MM). Nevertheless data about their potential complementarity for a more accurate assessment are limited. With this aim, we retrospectively analyzed the prediction of outcome with the combination of PET-CT and MRD, assessed by multiparameter flow cytometry (MFC) in 103 patients with newly diagnosed MM. We confirmed the benefit in terms of progression-free survival (PFS), linked to the achievement of negativity by MFC (hazard ratio [HR] 0.53; 95% confidence interval [CI]: 0.28-0.98), and PET-CT (HR 0.18; 95% CI: 0.09-0.36) individually. By combining both techniques, patients who became MRD-/PET-, with a median of PFS 92 months, had significant prolonged median PFS (P < .001). This is compared with MRD+/PET- and PET+ patients (median PFS of 45 and 28 months, respectively). We observed a significant difference (P = .003) in overall survival (OS) outcomes between MRD-/PET- and MRD+/PET- patients (4-year OS 94.2% and 100%, respectively), vs PET+ patients (4-year OS 73.8%). All survival results were confirmed in a conditional landmark analysis. These findings support the potential complementarity between PET-CT and MFC, and highlight their better predictive capability when improving sensitivity.

PB1766 ASSESSMENT OF MINIMAL RESIDUAL DISEASE IN ADULT EGYPTIAN ACUTE MYELOID LEUKEMIA PATIENTS

Background: The term minimal residual disease (MRD) is used to describe residual disease after suboptimal induction chemotherapy, but at the same time refers to the lowest levels of disease potentially compatible with cure or to molecularly defined relapse after long term remission. This study assesses the minimal residual disease in relation to the outcome in acute myeloid leukemia patients after 6 months of treatment of chemotherapy. Aims: The aim of this study is assessment of measurable minimal residual disease after treatment to identify acute myeloid leukemia patients who are at high risk of poor outcome. Methods: Minimal Residual Disease was measured using Flow cytometry in 30 newly diagnosed a 30 newly diagnosed acute myeloid leukemia (AML) patients. The patients were recruited from clinical hematology department at Ain shams university hospital over the period from May 2017 to November 2018. Results: A total number of 30 acute myeloid leukemia patients were recruited from Ain Shams University hospital, hematology and Oncology Unit outpatient clinic, with age ranging from 18-60 years old (median age 40 years), 14 of them were males representing 46.6% of the total number and 16 were females representing 53.3% of the total number. There was no statistical significance between the age of the studied group and the MRD with P-value 0.147, the sex of the patients doesn’t contribute to the risk stratification with a P-value of 0.200. The number of cases with negative MRD after induction was 13 representing 43.3% of the total number, and was 12 patients after 6 months representing 70.5% of the remitted patients, considering that the cut out value of MRD is 0.1. There was a significant relationship between TLC and MRD, the higher the TLC the more positive the MRD. Positive MRD is associated with higher mortality rates, exhibiting a statistical significance with P-value of 0.005. Summary/Conclusion: We concluded that assessment of minimal residual disease in AML is of great value in determination of prognosis of the disease and its outcome and it is of great value to determine the levels of minimal residual disease (MRD) during the course of therapy and to stratify patient to identify high risk patient and to plan the therapeutic program accordingly.

PF168 KINASE AND CYTOKINE RECEPTOR SIGNALING PATHWAY ACTIVATING ALTERATIONS IN UNIFORMLY TREATED B‐ALL

Background:Recent B‐acute lymphoblastic leukemia (B‐ALL) studies revealed a new subgroup of patients with ABL‐class and JAK‐STAT fusions which can be targeted using small‐molecule inhibitors (Roberts et al., 2017). Positivity for ABL‐class or JAK‐STAT fusions was associated with positive post‐induction minimal residual disease (MRD) (Pui et al., 2017) and inferior outcome (Boer et al, 2017) but most studies were conducted in non‐uniformly treated patient populations.Aims:To identify kinase and cytokine receptor pathway activating alterations and determine their clinical significance in uniformly treated B‐ALL.Methods:The study includes 160 BCR‐ABL1‐negative B‐ALL (122 pediatric, 38 adults (≥18 y/o)) patients treated according to MRD‐driven pediatric‐adult NOPHO ALL‐2008 protocol. 101 B‐ALL cases (including high hyperdyploids and low hipodyploids) without canonical B‐ALL aberrations were selected for targeted RNA‐Sequencing (RNA‐Seq). Sequencing was performed using TruSight Pan‐Cancer sequencing panel (Illumina Inc., CA). FISH analysis was used to identify CRLF2‐IGH gene rearrangements.Results:Of 101 B‐ALL patients (75 pediatric, 26 adults), RNR‐Seq and FISH analysis identified three (3%) cases with ABL‐class (ABL1‐ETV6, ABL2‐ZC3HAV1, PDGFRB‐EBF1) fusions and four (4%) cases with JAK‐STAT fusions (JAK2‐BCR, n = 1; CRLF2‐IGH, n = 3). Five of seven ABL‐class and JAK‐STAT mutually exclusive fusions were detected in adults. Remaining ten (9.9%) gene fusions were identified in the pediatric group, of which five cases had PAX5 gene and three had ZNF384 gene rearrangements.Gene mutation analysis detected Ras pathway mutations in a total of 48 (47.5%) cases: NRAS (n = 28), KRAS (n = 17), PTPN11 (n = 7). Other JAK‐STAT and FLT3‐TKD gene mutations were present in 10 (9.9%) and 8 (7.9%) cases, respectively. Thirty‐seven (36.6 %) patients harbored other gene variants (n = 23) or had no recurrent gene variants/fusions (n = 14) detected by RNA‐Seq.ABL‐class and JAK‐STAT fusions were more frequent among adults than pediatric patients (19.2% vs. 2.7%) while ABL‐class fusions were exclusive to adults (p = 0.032). The prognostic analysis was restricted to the adult group. More adult patients with ABL‐class or JAK‐STAT fusions had positive post‐induction day 29 MRD values compared to negative patients (p &lt; 0.001) and were more frequently assigned to NOPHO‐2008 high‐risk groups or had induction failure (80% vs 30.3%, p = 0.05). 75th percentile event‐free (EFS) and overall survival (OS) were 5 vs. 35 (p = 0.008) and 15 vs. 37 (p = 0.07) months in ABL‐class or JAK‐STAT fusion positive vs. negative adult groups, respectively.In multivariate analysis, the positivity for ABL‐class or JAK‐STAT fusions was an independent risk factor for worse EFS (p = 0.032) but not for OS (p = 0.242).Summary/Conclusion:Overall, ABL‐class and JAK‐STAT fusions were infrequent and were more often detectable in adults compared to children. Adult patients with ABL‐class or JAK‐STAT fusions had higher post‐induction MRD values and were more frequently assigned to high‐risk disease groups or had induction failure resulting in lower event‐free survival.

PF555 PROGNOSTIC VALUE OF NEXT GENERATION FLOW MONITORING CIRCULATING TUMOR PLASMA CELLS IN PERIPHERAL BLOOD ON MYELOMA PATIENTS AFTER TREATMENT

Background:After the introduction of novel and more‐effective therapies in multiple myeloma (MM) the number of patients achieving high quality responses has substantially increased, demanding the implementation of more sensitive methods to evaluate persistence of minimal residual disease (MRD) in bone marrow (BM) at very low levels. We have recently developed the Next Generation Flow (NGF) approach to assess medullary MRD in MM patients, which became the reference methodology by the International Myeloma Working Group (IMWG) to evaluate flow‐MRD status. Despite the clinical prognostic value of NGF BM MRD, sampling is limited to (few) specific timepoints throughout therapy. Nowadays, more frequent and less‐invasive approaches are used for a closer follow‐up (e.g., serum immunofixation ‐sIF‐). More recently, NGF has successfully been applied for the detection of circulating tumor plasma cells (CTPC) in peripheral blood (PB) of plasma cells neoplasms patients at diagnosis, providing significant diagnostic and risk stratification information; however, the prognostic impact of PB CTPC detection in MM patients after therapy has not been deeply explored.Aims:Here, we investigated the value of NGF for PB CTPC detection in post‐therapeutic MM patients and its relationship with paired BM MRD and sIF evaluations.Methods:Overall, we studied 309 paired PB and BM samples from 128 treated MM patients discriminated according to the IMWG response criteria. Both PB and BM samples were processed using the EuroFlow NGF MM‐MRD approach in parallel to sIF. The Kaplan–Meier method and the log‐rank test were used to plot and compare progression‐free survival (PFS) curves between groups. PFS was defined as time from sample evaluation to either disease progression or death by any reason. For all statistical analyses the SPSS (v. 23; IBM, Armonk, NY), was used. Statistical significance was set at p values &lt;0.05. Written informed consent was given by each patient prior to entering the study according to the Declaration of Helsinki.Results:Altogether, 26% of all MM analyzed (33/128) showed CTPC+ in PB. In turn, 49/128 (38%) of patients were BM MRD+ without CTPC in PB. Of note, CTPC were never detected in PB in the absence of BM involvement (n = 0/128). In addition, sIF+ results were present in close to one third of patients without PB CTPC (39/128; 30%), and 26% (10/39) of them being BM MRD−. Focusing on complete response (CR) or stringent CR (sCR) MM patients (i.e, sIF−; n = 65), 17% (11/65) were PB CTPC+. Median percentages and absolute CTPC counts in PB were significantly lower for those CR/sCR MM patients than observed in the whole cohort of CTPC+ cases (p &lt; 0.05): 0.0002% (range: &lt;0.0001%&gt;0.007%) and 15 CTPC/mL of PB (range: &lt;5–457 CTPC/mL) vs 0.002% (range: &lt;0.0001%&gt;0.6%) and 96 CTPC/mL of PB (range: &lt;5–18,352 CTPC/mL), respectively. Noteworthy, from the prognostic point of view, MM patients who were PB CTPC+ showed significantly shorter PFS rates vs PB CTPC− cases regardless of BM‐MRD status, both in the whole patient series and within CR/sCR patients (median PFS of 11 months vs not reached, respectively; p&lt;0.0001 in both comparisons).Summary/Conclusion:The high‐sensitive NGF approach allowed detection of PB CTPC in more than a quarter MM cases after treatment and in 17% of those in CR/sCR. Detection of PB CTPC identified a poor prognostic subgroup of patients (≈80% of relapse or death at 2 years). In summary, NGF can be applied in PB for non‐invasive monitoring of post‐therapeutic MM patients and provides complementary prognostic value to BM MRD and sIF.image

Minimal residual disease negativity using deep sequencing is a major prognostic factor in multiple myeloma

AbstractThe introduction of novel agents has led to major improvements in clinical outcomes for patients with multiple myeloma. To shorten evaluation times for new treatments, health agencies are currently examining minimal residual disease (MRD) as a surrogate end point in clinical trials. We assessed the prognostic value of MRD, measured during maintenance therapy by next-generation sequencing (NGS). MRD negativity was defined as the absence of tumor plasma cell within 1 000 000 bone marrow cells (<10−6). Data were analyzed from a recent clinical trial that evaluated the role of transplantation in newly diagnosed myeloma patients treated with lenalidomide, bortezomib, and dexamethasone (RVD). MRD negativity was achieved at least once during maintenance in 127 patients (25%). At the start of maintenance therapy, MRD was a strong prognostic factor for both progression-free survival (adjusted hazard ratio, 0.22; 95% confidence interval, 0.15-0.34; P < .001) and overall survival (adjusted hazard ratio, 0.24; 95% confidence interval, 0.11-0.54; P = .001). Patients who were MRD negative had a higher probability of prolonged progression-free survival than patients with detectable residual disease, regardless of treatment group (RVD vs transplant), cytogenetic risk profile, or International Staging System disease stage at diagnosis. These results were similar after completion of maintenance therapy. Our findings confirm the value of MRD status, as determined by NGS, as a prognostic biomarker in multiple myeloma, and suggest that this approach could be used to adapt treatment strategies in future clinical trials.

Classifying AML Patients with Inv(16) into High-Risk and Low-Risk Relapsed Patients Based on Peritransplantation Minimal Residual Disease Determined By CBFβ/MYH11 Gene Expression

A subtype of patients with core binding factor acute myeloid leukemia (AML) is characterized by the presence of the presence of inv(16)(p13q22) and rarely by a translocation t(16;16)(p13;q22). The final genetic product is the fusion of the CBFβ gene at 16q22 to the smooth muscle myosin heavy chain (MYH11) at 16p13, which is termed as CBFβ/MYH11 fusion gene. Although this type of AML is considered a favorable cytogenetic subgroup both in NCCN guideline or ELN classification, in particular with the application of high-dose cytarabine-based consolidation chemotherapy regimens, disease relapse remains one of the most important causes leading to death, occurring in around 35% of patients. Thus, for this cohort of patients, allogeneic hematopoietic stem cell transplantation (allo-HSCT) is needed to as salvage treatment to improve the overall survival.It has been reported that when patients achieved hematological remission, the MRD prior to transplantation (pre-MRD) has been demonstrated to be a useful parameter to predict leukemia relapse after allo-HSCT. Evaluating minimal residual disease (MRD) by real-time quantitative reverse transcriptase polymerase chain reaction (RQ-PCR) can quantify the expression level of fusion transcript at different time points along with the treatment. More recently, CBFβ/MYH11 fusion gene has been confirmed to be a good MRD marker and further screening out the patients in high-risk of relapse either during the treatment or after transplantation. However, due to the limit number of patients, there has been no studies about predictive value of CBFβ/MYH11expression after allo-HSCT.Therefore, in this study, we attempted to investigate the impact of pre-MRD determined by RQ-PCR-based CBFβ/MYH11 gene expression on transplant outcomes of AML patients with inv(16)(p13q22) or t(16;16)(p13;q22). Besides, our previous studies has demonstrated that in compared to HLA-identical transplantation, haplo-identical allo-HSCT had superior graft-versus-leukemia (GVL) effect in AML patients with standard-risk. Thus, here we also wanted to know whether the level of CBFβ/MYH11 pretransplant could further divide this form of AML into high-risk and low-risk relapse patients before allo-HSCT.Ninety AML patients with inv(16) in complete remission (CR) were monitored CBFβ/MYH11 transcript before and after allo-HSCT as MRD. A total of 23 patients received HLA-matched sibling donor transplantation (MSDT) and 67 patients received unmanipulated haploidentical hematopoietic stem cell transplantation (haplo-HSCT) were analyzed in this study. Patients were divided into four groups based on the value of CBFβ/MYH11 prior to transplantation (pre-MRD): with negative (group 1)/positive (group 2) pre-MRD before MSDT; with negative (group 3)/positive (group 4) pre-MRD before haplo-HSCT. The results showed that patients in group 2 had the highest cumulative incidence of relapse (2-year CIR, 40.7%), the lowest leukemia-free survival (2-year LFS, 50.8%) and the overall survival (2-year OS, 62.5%) among all four groups. The other three groups of patients had comparable CIR, TRM and OS (P>0.05). The patients were also classified into the other three groups according to CBFβ/MYH11 value of +1 month after transplantation: group 5: pre- and post-transplant MRD were both negative; group 6: the value of post-transplant MRD was lower than 0.2%; group 7: the value of post-transplant MRD was higher than 0.2%. Group 7 had the highest CIR compared to group 5 and 6 (P=0.217 & P=0.001, respectively) and the lowest LFS (P=0.072 & P=0.002, respectively), though the TRM and OS of these three groups were comparable (P>0.05). These results indicated that AML patients with inv(16) were able to be separated into high-risk and low-risk relapse groups based on peritransplant MRD determined by RQ-PCR-based CBFβ/MYH11. Haplo-HSCT might overcome the negative impact of pre-MRD on patient outcomes compared to MSDT. DisclosuresNo relevant conflicts of interest to declare.

Minimal Residual Disease Risk-Stratification in Pediatric Mixed Phenotype Acute Leukemia: Results of a Multi-Center Cohort Study

BACKGROUNDMixed phenotype acute leukemia (MPAL) is a rare form of leukemia in children. Current evidence supports the use of acute lymphoblastic leukemia (ALL)-directed regimens as initial therapy for MPAL; Children's Oncology Group (COG) ALL regimens are commonly used for pediatric ALL in the United States. Data for the predictive value of minimal residual disease (MRD) to risk-stratify therapy for pediatric MPAL is sparse overall and currently unknown in the context of COG ALL regimens. The primary objective for this study was to therefore examine the predictive value of MRD for event-free and overall survival (EFS, OS) in a centrally-reviewed, strictly-defined pediatric MPAL cohort treated according to COG ALL regimens. METHODSA retrospective cohort of pediatric MPAL treated from 2008-2016 was assembled from six institutions in the United States. All sites submitted primary diagnostic flow cytometry for central review. Two independent hematopathologists blinded to clinical outcomes confirmed the diagnosis of MPAL according to the WHO2008 and/or WHO2016 classification and assigned a MPAL phenotype. MRD was assessed by multi-parameter flow cytometry (“negative” defined as <0.01%). Endpoints of interest included presenting features of MPAL, MRD levels at end of induction and consolidation (EOI, EOC), role of hematopoietic stem cell transplantation (HSCT) in complete remission (CR), EFS, and OS. Kaplan-Meier analyses were performed stratified by predictors of interest. Stepwise multivariable Cox proportional hazard models inclusive of MRD and candidate predictors were used to evaluate EFS and OS for patients with complete data. Analyses were repeated in the subset of patients with “neutral” cytogenetics (i.e. no favorable [double trisomy, ETV6-RUNX1] or adverse [hypodiploid, BCR-ABL1, KMT2Ar, Ph-like, iAMP21, FLT3-ITD] features). All tests were 2-sided with significance set at p <0.05. RESULTSOf the 112 cases diagnosed by institutions as MPAL, 94 (84%) fulfilled strict WHO criteria. The majority of MPAL patients were B/Myeloid (89%), with a single blast population (87%), and without hyperleukocytosis (WBC≥50K/uL) or central nervous system involvement at presentation (Table 1). Within the cohort, 85/94 were treated with a COG ALL regimen with EOI MRD available (1/85 suffered an induction death prior to MRD assessment). ALL induction therapy resulted in a MRD-negative CR in 72% (61/85); three MRD-negative patients nonetheless converted to non-ALL therapy. Of those EOI MRD+ (≥0.01%), 12 of 14 who continued with COG ALL therapy achieved an EOC MRD-negative CR (i.e. 70/85 [82%] were MRD-negative by EOC). Induction failure (IF) occurred in 7% (6/85) and was defined as disease progression prior to EOI (n=2) or by EOI MRD ≥5% (n=4). The two patients with early disease progression were successfully “salvaged” with AML therapy (<21 days from initial diagnosis) and achieved a MRD-negative CR following one cycle. Patients achieving MRD-negative remissions at EOI and/or EOC with ALL chemotherapy had excellent EFS and OS (Figure 1). Multivariable analysis confirmed the predictive value of MRD at EOI (hazard ratio ±SE for EFS and OS = 3.77±1.67 and 3.54±2.09; p=0.032 and p=0.024 respectively). Only a few patients receiving ALL therapy proceeded to HSCT in CR1, all were alive at time of reporting. Use of HSCT was not associated with improved EFS or OS (p>0.50 for both); five-year EFS and OS for ALL chemotherapy without HSCT (n=73) were 78±6% and 90±4%, respectively. The presence of multiple blast populations of distinct lineages at diagnosis was similarly rare and was potentially associated with worse OS on multivariable analysis (p=0.024). No other candidate predictors were associated with EFS or OS. No difference in the predictive value of MRD was present when analyses were limited to patients with “neutral” cytogenetics. CONCLUSIONIn a retrospective analysis of pediatric MPAL, the majority of patients treated with ALL chemotherapy achieved a MRD-negative CR by EOC (~week 12 of therapy); overall survival in this group was excellent. Further prospective validation of MRD is essential to refine risk-stratified therapy for pediatric MPAL. Optimal salvage for those who fail to achieve remission with ALL chemotherapy is unknown and requires further study. DisclosuresO'Gorman:Becton Dickinson: Consultancy.

Prognostic Value of Minimal Residual Disease before Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Acute Myeloid Leukemia

IntroductionSeveral studies have shown that the minimal residual disease (MRD) in acute myeloid leukemia (AML) patients has a prognostic value after induction and consolidation therapy. Nevertheless the relapse is the most important cause of treatment failure in these patients, although they achieved a negative MRD, and even after an allogeneic hematopoietic stem cell transplantation (allo-HSCT). Nowadays, the value of the MRD before allogeneic BMT is still controversial.MethodMulticentric study where we have studied correlative AML patients who went under an allo-HSCT in a situation of complete response, between 2012 and April'18. The MRD was analyzed by 8-coloured multiparametric flow cytometry, at least with 2 tubes per patient and 1,000,000 events per tube. We evaluated the prognostic value of the MRD before allo-HSCT.ResultsBetween January'12 and April'18 we have gathered 90 allogeneic BMT in AML patients who were in CR, with a median age of 45 years old (17 - 66). The pre-HSCT situation was 1st complete remission (CR) in 75 patients and 2nd CR in 15. In 45 patients the conditioning regimen was myeoablative. In the group of patients (67) where we could know the risk group at diagnosis, the distribution was: low risk 18%, intermediate risk 59.7% and high risk 22.4%. The 46.7% of the donors were not related. In the last follow-up after allo-HSCT 24 patients have suffered a relapse (26.7%) and 41 (45.5%) have died (17 cases of mortality related to the transplant and 24 not related). In the global analysis the median follow-up of the overall survival (OS) was 37.5 months. Among the 90 patients, MRD was valuable in 86. Ten of 59 patients (16.9%) with negative MRD relapsed vs 12/27 (44.4%) with positive MRD, p= 0.016. If we consider only patients in 1st CR, 9/50 (18%) patients with negative MRD relapsed vs 10/22 (45.5%) with positive MRD, p= 0.02. This statistically significant difference does not exist if we consider only patients in 2nd CR. The median follow-up of OS and event free survival (EFS) was not reached in the negative MRD group and 571 days and 299 days in the positive MRD group. OS and EFS at 2 years after transplantation were 65% and 64% in the negative MRD group and 42% and 37% in the positive MRD group, p= 0.03 and p= 0.008 respectively (figure 1).ConclusionsThe detected MRD by 8-colour multiparametric flow cytometry previous an allo-HSCT in patients with AML in 1st CR is a prognostic factor in terms of relapse. Patients with a positive MRD before the allo-HSCT have a poorer OS and EFS than the patients with a negative MRD. DisclosuresNo relevant conflicts of interest to declare.

First Prospective Data on Impact of Minimal Residual Disease on Long-Term Clinical Outcomes after Venetoclax Plus Rituximab Versus Bendamustine Plus Rituximab: Phase III MURANO Study

First Prospective Data on Impact of Minimal Residual Disease on Long-Term Clinical Outcomes after Venetoclax Plus Rituximab Versus Bendamustine Plus Rituximab: Phase III MURANO Study

Early vs. late MRD response- and risk-based treatment intensification of childhood acute lymphoblastic leukemia: a prospective pilot study from Saudi Arabia

BackgroundRefinement of risk-based treatment stratification by minimal residual disease (MRD) at different time points has improved outcomes of childhood acute lymphoblastic leukemia (ALL). In this prospective study we evaluated effects of such stratification, including intensification of therapy based on response assessment at day-15 and MRD at day-29 of induction to test if treatment intensification would improve outcomes.Methods241 patients, 1–14 years old, newly diagnosed with ALL, were recruited and stratified by risk and MRD response into three treatment Arms (A, B, or C). Arm A was modified from COG AALL0331, B from AALL0232, and C from AALL0232 and AALL0434. Assignments were according to NCI risk, phenotype, rapid vs. slow early response (SER), steroid pretreatment, MLL rearrangement (MLLR), CNS3, and testicular involvement. Patients on Arm A had treatment intensified early based on day-15 marrow results or late based on end-of-induction MRD.Results5-year OS, EFS, and CIR were 89.5% ± 4.0%, 87.6% ± 4.3%, and 7.1% ± 3.5%. No significant difference was found by B- vs. T cell phenotype. 5-year OS, EFS, and CIR for B-cell ALL were 90.5% ± 2.4%, 88.7% ± 2.6%, and 6.4% ± 2.0%. Outcomes for patients with t(1;19)/TCF3-PBX1 and MLLR were significantly (p ≤ 0.05) worse than for other patients. MRD level at end-of-induction associated with outcomes, but association with a specific MRD value at end-of-induction varied significantly by NCI-risk group. Late treatment intensification based on end-of-induction MRD significantly improved survival outcomes for NCI-SR patients, however, patients with NCI-HR and positive MRD at end-of-induction had significantly inferior outcomes despite intensification. MRD transitions between day-15 and day-29 of induction associated with differences for OS and EFS.ConclusionsArm switching to a more intensive protocol had mixed results. Assigning patients by end-of-induction MRD-risk alone did not reflect response kinetics of the different NCI-risk groups. Although late treatment intensification improved outcomes of NCI-SR patients with positive MRD at end-of-induction, further refinement is needed to improve outcomes of NCI-HR with SER. Integration of NCI-risk group with specific MRD value and time point allows more refined treatment stratification.Trial Registration Protocols were approved by King Abdullah International Medical Research Center and Ethics Review Committee RC08053J

Clinical significance of minimal residual disease in patients with Ph-negative precursor B-acute lymphoblastic leukemia

目的探讨微小残留病（MRD）水平在Ph染色体阴性的急性B淋巴细胞白血病（Ph− B-ALL）中的预后意义。方法采用多色流式细胞术对2010年9月至2017年11月初诊的193例Ph− B-ALL患者在治疗后1、3、6个月进行骨髓MRD监测，并对不同MRD水平患者的预后进行比较。结果中位随访22（1~92）个月，所有193例患者共行497次MRD检测。1个月时MRD水平<0.1%和≥0.1%患者的3年预期无复发生存（RFS）率分别为74.5%和29.9%，3年预期总生存（OS）率分别为67.5%和30.3%；3个月时MRD水平阴性和阳性患者的3年预期RFS率分别为75.6%和29.7%，3年预期OS率分别为71.6%和27.8%；6个月时MRD水平阴性或阳性患者的3年预期RFS率分别为74.6%和11.6%，3年预期OS率分别为74.0%和15.7%，差异均有统计学意义（P值均<0.001）。3个监测点全部达到MRD阴性标准的患者与至少1次未达到MRD阴性标准的患者比较，3年预期RFS、OS率差异均有统计学意义（80.5%对30.5%，77.1%对29.4%，P值均<0.001）。多因素分析结果显示，3个月时的MRD水平是Ph− B-ALL患者独立的预后因素之一。结论治疗后MRD监测对Ph− B-ALL的预后判断有重要意义。

Prognostic value of minimal residual disease and polyclonal plasma cells in myeloma patients achieving a complete response to therapy.

8030Background: Achievement of a complete response (CR) to therapy has been associated with improved outcomes in patients with multiple myeloma (MM). More recently, increasing application of minima...

MINIMAL RESIDUAL DISEASE ASSESMENT IN PATIENTS WITH ACUTE MYELOID LEUKEMIA BY MULTICOLOUR FLOW CYTOMETRY (LITERATURE REVIEW)

Patients with acute myeloid leukemia (AML) have a high risk of relapse. Determination of the presence of residual tumor cells during the remission of AML allows predicting the onset of relapse. Slow decrease of blast cells after induction courses is associated with a high probability of relapse. There are two most sensitive methods for determining minimal residual disease (MRD): molecular (polymerase chain reaction – PCR, droplet digital PCR, next generation sequencing – NGS) and immunophenotypic (multicolor flow cytometry – MFC). Both methods have advantages and disadvantages. The molecular diagnostic method is more sensitive, but it takes more time to get the result (from several days). Measurement of MRD by PCR is applicable in 40–50 % of AML patients, and by MFC – in 90 % of patients. The MFC method is based on the identification of antigens combination that is characteristic of tumor cells and is not found on normal hematopoietic cells. There are several drawbacks of the MFC method: the change of tumor clone immunophenotype during treatment, the inadequate difference in the antigen profiles of tumor cells and normal cells, difficulties in evaluating the MRD status in low cellularity bone marrow or blood sample. In AML patients the effect of MRD, measured by the MFC method, on long-term treatment outcomes was well-demonstrated. Evaluation of early MRD status shows tumor chemosensitivity and therapy efficacy. Despite the different approaches in MRD detection, thresholds and the combination of monoclonal antibodies, the lack of standardization, “positive” MRD values in early or later stages of therapy worsen the disease-free (DFS) and overall survival (OS) in AML patients. So far, the principles of MRD-directed therapy have not been developed, but protocols exist with the use of targeted drugs in combination with standard chemotherapy that help to reduce the MRD level. It is proved that the intensification of treatment does not affect the quantitative value of MRD and the long-term results of therapy. New prospective studies are needed to search for universal MRD markers, to create a standardized panel of monoclonal antibodies and to develop a specific therapy strategy in accordance with the MRD values.

Comparative Analysis of Flow Cytometry and RQ-PCR for the Detection of Minimal Residual Disease in Philadelphia Chromosome–Positive Acute Lymphoblastic Leukemia after Hematopoietic Stem Cell Transplantation

The aim of this study was to examine the value of minimal residual disease (MRD) detection by multiparameter flow cytometry (MFC) and real-time quantitative PCR (RQ-PCR) at the early stage after hematopoietic stem cell transplantation for predicting relapse and leukemia-free survival (LFS) in Philadelphia chromosome–positive acute lymphoblastic leukemia (Ph+-ALL). Patients who maintained complete molecular remission (BCR-ABL <.01%) status at 1 and 3 months were associated with a lower relapse rate (P = .02 and <.001) and better LFS (P = .014 and .013) than were those without a complete molecular remission. Negative MFC at 1, 2, and 3 months was associated with a lower relapse rate (P = .01, .004, and .04, respectively) and better LFS (P = .044, <.0001, and .013, respectively). Multivariate analysis showed that MRD positivity identified by MFC or RQ-PCR at 3 months was an independent risk factor for relapse (hazard ratio [HR], 6.042 (95% confidence interval [CI], 2.283 to 15.988), P < .001), LFS (HR, 3.614 (95% CI, 1.610 to 8.111), P = .002), and overall survival (HR, 2.547, 95% CI, 1.008 to 6.443), P = .048). In summary, MRD detection by MFC and RQ-PCR detection of BCR-ABL at the early stage were important predictors of outcome in patients with Ph+-ALL, and these tests played complementary roles in predicting prognosis.

Predictive value of minimal residual disease in Philadelphia-chromosome-positive acute lymphoblastic leukemia treated with imatinib in the European intergroup study of post-induction treatment of Philadelphia-chromosome-positive acute lymphoblastic leukemia, based on immunoglobulin/T-cell receptor and BCR/ABL1 methodologies

The prognostic value of minimal residual disease (MRD) in Philadelphia-chromosome-positive (Ph+) childhood acute lymphoblastic leukemia (ALL) treated with tyrosine kinase inhibitors is not fully established. We detected MRD by real-time quantitative polymerase chain reaction (RQ-PCR) of rearranged immunoglobulin/T-cell receptor genes (IG/TR) and/or BCR/ABL1 fusion transcript to investigate its predictive value in patients receiving Berlin-Frankfurt-Münster (BFM) high-risk (HR) therapy and post-induction intermittent imatinib (the European intergroup study of post-induction treatment of Philadelphia-chromosome-positive acute lymphoblastic leukemia (EsPhALL) study). MRD was monitored after induction (time point (TP)1), consolidation Phase IB (TP2), HR Blocks, reinductions, and at the end of therapy. MRD negativity progressively increased over time, both by IG/TR and BCR/ABL1. Of 90 patients with IG/TR MRD at TP1, nine were negative and none relapsed, while 11 with MRD<5×10−4 and 70 with MRD≥5×10−4 had a comparable 5-year cumulative incidence of relapse of 36.4 (15.4) and 35.2 (5.9), respectively. Patients who achieved MRD negativity at TP2 had a low relapse risk (5-yr cumulative incidence of relapse (CIR)=14.3[9.8]), whereas those who attained MRD negativity at a later date showed higher CIR, comparable to patients with positive MRD at any level. BCR/ABL1 MRD negative patients at TP1 had a relapse risk similar to those who were IG/TR MRD negative (1/8 relapses). The overall concordance between the two methods is 69%, with significantly higher positivity by BCR/ABL1. In conclusion, MRD monitoring by both methods may be functional not only for measuring response but also for guiding biological studies aimed at investigating causes for discrepancies, although from our data IG/TR MRD monitoring appears to be more reliable. Early MRD negativity is highly predictive of favorable outcome. The earlier MRD negativity is achieved, the better the prognosis.