Measurable Residual Disease Positivity Research Articles

Molecular, clinical, and therapeutic determinants of outcome in NPM1 mutated AML

AbstractAlthough NPM1-mutated acute myeloid leukemia (AML) carries a generally favorable prognosis, many patients still relapse and die. Previous studies identified several molecular and clinical features associated with poor outcomes; however, only FLT3-internal tandem duplication (ITD) mutation and adverse karyotype are currently used for risk stratification because of inconsistent results and uncertainty about how other factors should influence treatment, particularly given the strong prognostic effect of postinduction measurable residual disease (MRD). Here, we analyzed a large group of patients with NPM1 mutations (NPM1mut) AML enrolled in prospective trials (NCRI AML17 and AML19, n = 1357) to delineate the impact of baseline molecular and clinical features, postinduction MRD status, and treatment intensity on the outcome. FLT3-ITD (hazard ratio [HR], 1.28; 95% confidence interval [CI], 1.01-1.63), DNMT3A (HR, 1.65; 95% CI, 1.32-2.05), WT1 (HR, 1.74; 95% CI, 1272-2.38), and non-ABD NPM1mut (HR, 1.64; 95% CI, 1.22-2.21) were independently associated with poorer overall survival (OS). These factors were also strongly associated with MRD positivity. For patients who achieved MRD negativity, these mutations (except FLT3-ITD) were associated with an increased cumulative incidence of relapse (CIR) and poorer OS. However, apart from the few patients with adverse cytogenetics, we could not identify any group of MRD-negative patients with a CIR >40% or with benefit from allograft in first remission. Intensified chemotherapy with the FLAG-Ida regimen was associated with improved outcomes in all subgroups, with greater benefits observed in the high-risk molecular subgroups.

Clonal relapse dynamics in acute myeloid leukemia following allogeneic hematopoietic cell transplantation

AbstractPatients with acute myeloid leukemia (AML) who experience relapse following allogeneic hematopoietic cell transplantation (alloHCT) face unfavorable outcomes regardless of the chosen relapse treatment. Early detection of relapse at the molecular level by measurable residual disease (MRD) assessment enables timely intervention, which may prevent hematological recurrence of the disease. It remains unclear whether molecular MRD assessment can detect MRD before impending relapse and, if so, how long in advance. This study elucidates the molecular architecture and kinetics preceding AML relapse by using error-corrected next-generation sequencing (NGS) in 74 patients with AML relapsing after alloHCT, evaluating 140 samples from peripheral blood collected 0.6 to 14 months before relapse. At least 1 MRD marker became detectable in 10%, 38%, and 64% of patients at 6, 3, and 1 month before relapse, respectively. By translating these proportions into monitoring intervals, 38% of relapses would have been detected through MRD monitoring every 3 months, whereas 64% of relapses would have been detected with monthly intervals. The relapse kinetics after alloHCT are influenced by the functional class of mutations and their stability during molecular progression. Notably, mutations in epigenetic modifier genes exhibited a higher prevalence of MRD positivity and greater stability before relapse, whereas mutations in signaling genes demonstrated a shorter lead time to relapse. Both DTA (DNMT3A, TET2, and ASXL1) and non-DTA mutations displayed similar relapse kinetics during the follow-up period after alloHCT. Our study sets a framework for MRD monitoring after alloHCT by NGS, supporting monthly monitoring from peripheral blood using all variants that are known from diagnosis.

Nomogram predictive models for adult patients with acute lymphoblastic leukaemia based on real-world treatment outcomes.

This study aimed to analyse the characteristics and treatment outcomes of adult patients with acute lymphoblastic leukaemia (ALL) and construct nomogram predictive models for prognosis prediction. Between January 2017 and June 2022, 462 adult patients with ALL were included in this retrospective analysis. Patients' ages ranged from 14 to 84 years. B-cell origin was observed in 82.7% of these patients, while 17.3% of the cases were of T-cell origin. The BCR/ABL1 fusion gene was detected in 32.9% of those with B-ALL. Complete remission was achieved in 83.7% of the patients after induction chemotherapy. The median disease-free survival (DFS) and overall survival (OS) of patients were 19.0 and 39.1 months, respectively. The 5-year DFS and OS rates were 29.5% and 41.8%, respectively. The BCR/ABL1 fusion gene had a significant adverse impact on DFS and OS when patients were treated with tyrosine kinase inhibitors (TKIs) and chemotherapy; however, this effect was eliminated when patients underwent transplantation. Multivariate analysis identified that age ≥ 35 years, white blood cell count ≥ 30 × 109/L, platelet count < 100 × 109/L, failure to achieve complete remission after induction chemotherapy, positive measurable residual disease (MRD), and absence of transplantation were independent adverse prognostic factors for DFS and/or OS. Nomogram predictive models constructed by the rms package in R software based on these prognostic factors demonstrated precise predictive value. In conclusion, adult patients with ALL experience poor survival. TKIs in combination with transplantation can eliminate the adverse effects of BCR/ABL1 fusion genes on prognosis. Nomogram predictive models were accurate for prognostic prediction and will be useful in clinical practice.

Assessment of Measurable Residual Disease on Day 28 of First Induction Chemotherapy in Acute Myeloid Leukaemia Patients

Background: Measurable residual disease (MRD) is an independent, strong, prognostic marker in acute myeloid leukaemia (AML) that is important for risk stratification and treatment planning. This study assessed the MRD on day-28 after first induction chemotherapy in AML patients. Objective: To assess measurable residual disease status on day 28 after the first induction chemotherapy in newly diagnosed acute myeloid leukaemia patients. Methodology: This cross-sectional study was conducted at the Department of Haematology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka from April 2021 to March 2022 among a total of 25 newly diagnosed AML patients who were admitted and received induction chemotherapy with DA (7+3). On Day-28, bone marrow aspiration was done with standard procedure and first pull of 2ml bone marrow sample was sent to a laboratory for MRD evaluation by multiparameter flow cytometry. MRD was considered positive when value was ?0.1%. Results: On day 28 of post induction chemotherapy most of the patients (92%) achieved morphological remission and among them more than half (52.2%) were MRD positive. The presence of CD14 myeloid marker and baseline higher serum uric acid level was significant in MRD positive patients and cytarabine dose 150 mg/m2 was found significant in MRD negative patients. Conclusion: More than half of the Acute Myeloid Leukaemia patients, treated with standard induction chemotherapy and achieved morphological remission on day 28 of chemotherapy, had positive measurable residual disease assessed by multiparameter flow cytometry. Positive MRD indicates relatively poorer prognosis and may necessitate more cycles of induction followed by more intensive consolidation which may include haematopoietic stem cell transplantation.

Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia in Children: A Retrospective Cohort Study at a Pediatric Oncology Center.

Background and objective Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL Ph+) is quite rare among pediatric patients. Its management has undergone significant changes in the past few years, leading to some variability in how it is approached. At the Portuguese Oncology Institute of Porto (IPOP),a tertiary oncological center, the standard of carehas been aligned with the guidelines proposed by the European intergroup study of post-induction treatment of ALL Ph+ (EsPhALL). In this study, we aimed to examine the experience and outcomes related tothe treatment of pediatric patients with ALL Ph+ at IPOP. Methods This retrospective cohort study involvedpediatric patients diagnosed with ALL Ph+ at IPOP between January 2008 and December 2022 and analyzed their outcomes. Results A total of 14 patients were included. IKFZ1 was altered in five patients (out of nine in whom it was searched). Five patients were treated according to EsPhALL 2004, which involved starting imatinib later in a discontinuous manner [resulting in both five-year overall survival (OS) and progression-free survival (PFS) of 60%]. The EsPhALL 2010 (preconizing a continuous imatinib regimen instead) was employed in three patients, with a five-year OS and PFS of 66.7%. Allchildren mentioned above received cranial irradiationtherapy (CRT). Finally, six were treated according to the EsPhALL 2015, which stopped including CRT in its backbone. The five-year OS was 100%, whereas every patient progressed with an increase in BCR::ABL1 levels greater than 1-log. Moreover, until 2015, all patients had been recommended to undergo allogeneic hematopoietic stem cell transplantation (alloHSCT). However, since 2015, alloHSCT has been exclusively reserved for relapsed/refractory (R/R) disease or poor responders with positive measurable residual disease (MRD). In total, alloHSCT was performed in nine patients. Conclusions Although initially associated with a poor prognosis, the ALL Ph+ paradigm is drastically shifting. Further studies will hopefully clarify the outcomes in this population and help understand the role of central nervous system (CNS) prophylaxis, alloHSCT, and MRD quantification.

Clinical analysis of 14 patients aged ≤ 50 years with high-risk multiple myeloma treated with allogeneic hematopoietic stem cell transplantation

Objective: To evaluate the efficacy of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in young patients with high-risk multiple myeloma (HRMM) and analyzed the factors affecting patient prognosis. Methods: In this retrospective study, we analyzed the clinical data of 14 patients with HRMM with cytogenetic abnormalities or high-risk biological factors who underwent allo-HSCT at the Hematopoietic Stem Cell Transplantation Center of the Institute of Hematology & Blood Diseases Hospital between November 2016 and November 2022. Results: There were seven males and seven females included in the study, with a median age of 39.5 (31-50) years at the time of allo-HSCT. The median number of treatment lines before transplantation was 2 (1-6) . Before allo-HSCT, 42.9% (6/14) of the patients did not achieve complete remission, while 35.7% (5/14) of the patients achieved measurable residual disease positivity. After transplantation, all patients were evaluated for their treatment response, and the overall response rate was 100% (14/14) . All 14 patients successfully underwent allo-HSCT, with median engraftment times for neutrophils and platelets of 11 (10-14) days and 13 (9-103) days, respectively. Acute grade Ⅱ-Ⅳ graft-versus-host disease (GVHD) occurred in five patients (35.7%) , and two patients (14.3%) developed moderate-to-severe chronic GVHD. The median follow-up time after allo-HSCT was 18.93 (4.10-72.53) months, with an expected 2-year transplant-related mortality rate of 7.1% (95% CI 0%-21.1%) and an expected 2-year overall survival rate of 92.9% (95% CI 80.3%-100.0%) . Moreover, the expected 1-year and 2-year progression-free survival rates were 92.9% (95% CI 80.3%-100.0%) and 66.0% (95% CI 39.4%-100.0%) , respectively, and the 2-year cumulative incidence of relapse was 28.9% (95% CI 0%-56.7%) . Upfront allo-HSCT following complete remission after induced therapy and the presence of chronic GVHD might be favorable prognostic factors. Conclusion: allo-HSCT is an effective treatment for improving the prognosis of young patients with HRMM.

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

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

Myelodysplasia-Related Gene Mutations for NGS-Based MRD Assessment in Acute Myeloid Leukemia

Introduction: Measurable residual disease (MRD) plays an increasing role for treatment management of AML patients. While next-generation-sequencing (NGS) based MRD assessment can be well standardized, there is uncertainty about the type of gene mutations that associate with prognosis and are useful for MRD assessment. The 2022 ELN recommendations assign patients with at least one mutation in the genes ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1 or ZRSR2 to the subgroup of myelodysplasia-related gene mutations (MRGM), which is associated with poor prognosis. We aimed to define the prognostic effect of MRD after induction chemotherapy in AML patients with MRGM using MRG mutations for MRD assessment by NGS. Methods: We retrospectively collected bone marrow and peripheral blood samples from AML patients in complete remission (CR) or CR with incomplete hematologic recovery (CRi) after one to two cycles of 7+3-based standard induction chemotherapy (IC) with at least one MRGM detected at diagnosis by myeloid panel sequencing covering 48 AML associated genes. Patients treated with one course of IC were included if they proceeded to allogeneic hematopoietic cell transplantation (alloHCT) already after one cycle. Molecular MRD status was assessed using targeted NGS and bioinformatics error-correction with 0.01% sensitivity as described before using only MRGM as MRD markers. Results: MRD was assessed on 104 adult newly-diagnosed AML patients (median age 58.6) with a total of 166 MRGM, resulting in a median of one MRGM per patient (range 1-4). 43 (41.3%) patients had secondary or therapy-related AML and 20 (19.2%) had myelodysplasia-related cytogenetic abnormalities. 68 (65.4%) patients were MRD positive for at least one MRGM after one (18 patients (17.3%)) or two (86 patients (82.7%)) cycles of intensive chemotherapy, while 36 (34.6%) became MRD negative. Measured variant allele frequencies (VAF) of positive samples ranged from 0.02-43.1% (median VAF 1.34%).MRD positive patients were older and more likely to be male compared to MRD negative patients, while cytogenetic risk, WBC count, Hgb, platelet count and ECOG status at diagnosis were similar to MRD negative patients. 53 (77.9%) MRD positive and 23 (63.9%) MRD negative patients underwent alloHCT in first CR/CRi.Median follow-up was 3.35 years. OS (P = 0.92), RFS (P = 0.99) and CIR (P = 0.98) were similar in MRD positive (at least one MRGM detectable) and negative (no MRGM detectable) patients (Figure 1). OS, RFS and CIR were also similar between MRD positive and negative patients, when MRD negativity was defined by conversion of at least one MRGM to negativity (55 (52.9%) MRD positive, 49 (47.1%) MRD negative), and when ASXL1 was excluded from the analysis. As variants with VAF &amp;gt;5% in CR/CRi samples may indicate clonal hematopoiesis, we excluded all variants with VAF &amp;gt;5% and repeated the analysis with the 88 (84.6%) remaining patients. Again, OS, RFS and CIR were similar for MRD positive and negative patients. We next reasoned that reduction of VAF correlates with the sensitivity of leukemic cells and possibly with depth of remission and long-term outcome. The fold-reduction of VAFs from diagnosis to the time of MRD analysis was calculated for all variants. For patients with several MRGMs, the variant with the largest fold-reduction was considered including undetectable variants. Patients with more or less than a 2-log, 3-log or 4-log reduction (log 10) had similar OS, RFS and CIR, respectively. Evaluating each MRGM individually, only RUNX1-MRD associated with RFS and by trend CIR (comparing MRD positive to negative patients for OS, HR 3.41, 95% CI 0.43-26.82, P = 0.24; RFS, HR 4.37, 95% CI 1.07-17.79, P = 0.04; CIR, HR 3.30, 95% CI 0.79-13.82, P = 0.1). Conclusion: 65.4% of AML-MRGM patients in CR/CRi remained MRD positive when MRGMs were used for MRD assessment by NGS. MRD positivity was associated with age above 60 years and male sex.Using all MRG mutations for MRD assessment at a threshold of 0.01% or by various degrees of log-reduction was not predictive of outcome after intensive induction chemotherapy. This limits the number of potential MRD markers for NGS analysis before alloHCT, although individual markers like RUNX1 may be of prognostic value.

Reshaping MRD Detection Strategies: Next-Generation Sequencing and High DNA Input Identify Previously Missed Measurable Residual Disease in Peripheral Blood of B-Cell Precursor Acute Lmyphoblastic Leukemia

Background: In acute lymphoblastic leukemia (ALL), measurable residual disease (MRD) is the most important prognostic factor. MRD is traditionally quantified in bone marrow aspirates (BM) using real-time quantitative polymerase chain reaction (RQ-PCR) according to EuroMRD standards. Since the emergence of modern molecular methods, it has been a continuous effort to enable MRD assessment from peripheral blood (PB). The less invasive material collection would allow closer MRD monitoring and solve technical challenges of BM aspiration, such as skewed or non-representative MRD values due to hemodilution and unequal distribution of leukemic cells. While several studies demonstrated comparable MRD values of BM and PB in T-ALL, in B-cell precursor ALL (BCP-ALL) MRD determination from PB is still a challenge. Mean MRD levels in PB are considerably lower than in BM and frequently escape detection. Additionally, paired samples show a highly variable MRD level ratio in both pediatric and adult cases (Kotrova et al, Leukemia 2020). Objective: BCP-ALL cases with known MRD positivity in the BM likely also harbor MRD positive cells in the PB, even when missed by traditional methods. With more sensitive assays, either by increased DNA input or by application of amplicon-based next generation sequencing (NGS), MRD detection from PB may improve in these cases. Methods: We retrospectively selected PB - BM sample pairs of 74 BCP-ALL patients with BM MRD positivity (43 with quantifiable MRD positivity and 31 with positivity below quantitative range) and sufficient leftover DNA from a cohort of patients treated according to GMALL protocols, where conventional RQ-PCR of clonal immunoglobuline heavy chain (IGH) VJ/DJ gene rearrangements failed to detect PB MRD. MRD had been determined by standard RQ-PCR with 1.5 µg DNA in BM and PB, respectively, according to the EuroMRD guidelines (van der Velden et al, Leukemia 2007). PB samples were re-tested for MRD with high DNA input RQ-PCR using 6.6 µg DNA and amplicon-based NGS, each using 6.6 µg DNA, as well as standard input NGS. NGS analyses of corresponding PB and BM samples were performed with the EuroClonality amplicon-based NGS assay (Brüggemann et al, Leukemia 2019). Identification and quantification of leukemia-derived clonotypes was done using ARResT/Interrogate. Results: In total, 74 BCP-ALL patients with pre/c-B-ALL (n=60) and pro-B-ALL (n=14) were included. Patient age ranged from 19 - 71 years with a median of 44.5. In all included samples (56 in first-line therapy and 18 salvage treatment), BM was MRD positive and PB was MRD negative in standard RQ-PCR at a sensitivity of at least 10 -4. To assess the effect of high DNA input alone, RQ-PCR was repeated in PB with high DNA input for 59 patients and 63 IGH VJ/DJ markers. At least one positive signal was detected in 19/59 patients (32%) and 20/63 markers (32%) (FIGURE 1A). NGS was performed for 73 PB samples and 84 markers using standard and high DNA input. With standard DNA input, MRD could be detected for 19/73 patients (26%) and 21/84 markers (25%) (FIGURE 1A). In the high input approach, MRD was detected in 36/73 patients (49%) and 40/84 markers (48%) (FIGURE 1A). A quantifiable MRD value was identified in 17 patients and 19 markers. All markers with quantifiable NGS MRD positivity in PB showed higher MRD values in the corresponding BM sample and MRD values below 10 -4 (FIGURE 1B). No correlation of MRD in paired samples could be demonstrated (Pearson correlation coefficient: 0.09) (FIGURE 1B). Conclusion: In BCP-ALL, MRD detection from PB is challenging with conventional methods. Increased DNA input and amplicon-based NGS allowed detection of MRD in a subset of PB samples that were negative in standard RQ-PCR. With identical DNA input, NGS showed a higher sensitivity than RQ-PCR and best results were achieved when high DNA input and NGS were combined, identifying MRD in nearly half of the PB samples. These results demonstrate that PB can be a valuable tool for early MRD detection in BCP-ALL when adjusting traditional MRD assessment strategies. However, in half of the samples, MRD was still missed by high input NGS. Even with assays improved for sensitivity, PB therefore cannot fully replace BM for MRD assessment in BCP-ALL yet and should rather be considered to complement BM analyses or in cases where BM is not accessible.

Next-Generation Sequencing (NGS) for Residual Disease (MRD) Monitoring in T-Lymphoblastic Leukemia (T-ALL)

Background: Flow Cytometry is the current standard for detection of measurable residual disease (MRD) in T-lymphoblastic leukemia (T-ALL) for North America but relies on subjective interpretation of data by a highly trained interpreter, which raises concerns for reproducibility between laboratories. Nevertheless, MRD &amp;gt; 0.01% at End of Induction (EOI) and End of Consolidation (EOC) have been associated with poorer outcome in T-ALL. MRD detection by next-generation sequencing (NGS) offers the potential for reduced subjectivity and increased sensitivity, as has already been demonstrated in B-lymphoblastic leukemia. This study assesses the performance characteristics and potential contribution of NGS for the detection of T-ALL MRD in pediatric patients. Method: Residual patient samples from COG AALL1231 concurrently tested for T-ALL MRD by flow cytometry were tested for the presence of leukemia-associated clonal TCRB sequences at the University of Washington using the immunoSEQ kit from Adaptive Biotechnologies. The sensitivity of the assay for these samples is estimated at 0.002%. The samples included 615 pretreatment samples, 298 EOI samples, and 72 EOC samples. The EOI samples were negative for MRD by flow cytometry (MRD&amp;lt;0.01%). The EOC samples were from patients positive for MRD at EOI, as per the treatment protocol. 111 samples lacking a pretreatment clonal TCRB sequence for which residual material was available were submitted to Adaptive Biotechnologies for TCRG sequencing. ETP status was determined on pre-treatment samples by flow cytometry. A pretreatment clonal sequence representing &amp;gt; 19% of the total T cell sequences was considered leukemia-associated and the presence any leukemia-associated clonal sequence post-treatment was considered MRD positive. The MRD results were correlated with clinical outcome. Results: Clonal TCRB leukemia-associated sequences were identified in 68.5% of pretreatment samples and correlated with ETP status (ETP 3.6% (N=56) , Near-ETP 44.8% (N=96), Not-ETP 82.4% (N=449), unknown 50% (N=14)). Clonal TCRG leukemia-associated sequences were identified in an additional 44.1% of pretreatment samples lacking a clonal TCRB sequence (N=111). EOI MRD was identified in 71.0% of samples assayed for TCRB (ETP not evaluable (N=0), Near-ETP 76.2% (N=21), Not-ETP 70.3% (N=263), Unknown 77.8% (N=9)). Additional EOI samples not informative for TCRB and assayed for TCRG (N=29) identified 89.7% as MRD positive. EOC MRD was identified in 63.9% of samples assayed for TCRB (ETP 66.7% (N=3), Near-ETP 45.5% (N=11), Not-ETP 68.4% (N=57), Unknown 0% (N=1)). Additional EOC samples not informative for TCRB and assayed for TCRG (N=35) identified as 68.6% MRD positive. Correlation of MRD status with clinical outcome data revealed no difference in disease-free survival (DFS) at either EOI or EOC, although all relapses but one at each timepoint (N=15 EOI, N=15 EOC) occurred in the MRD positive groups. Conclusion: A significant subset of T-ALL samples do not contain clonal leukemia-associated TCRB or TCRG sequences (31.5% for TCRB, 17.6% using both TCRB or TCRG) and cannot be evaluated for MRD using this NGS approach. Samples lacking a clonal leukemia-associated sequence are associated with an immature immunophenotype (ETP or Near-ETP), although 17.6% of Not-ETP samples also lack a clonal sequence, suggesting that flow cytometric classification of maturational stage is likely imperfect. A high frequency of MRD positivity is present at both EOI and EOC that does not reflect the excellent outcome that most patients experience, thus raising concerns about the specificity of these clonal sequences at very low levels of detection. Evaluation of sequence specificity across the cohort and use of higher MRD thresholds to optimize the correlation with clinical outcome is underway. A negative MRD result by NGS has a high negative predictive value for relapse/death at either EOI (95.2%) or EOC (92.9%) but a poor positive predictive value (6.8% at both EOI and EOC).

Toward a Measurable Residual Disease-Based Algorithm for Selection of Allogeneic Hematopoietic Stem Cell Transplant in Acute Myeloid Leukemia

Background: The diagnosis and management of acute myeloid leukemia (AML) have transformed in recent years with an improved understanding of leukemogenesis and improved methods of measurable residual disease (MRD) detection. Current treatment algorithms include consideration of allogeneic hematopoietic stem cell transplant (HCT) for intermediate and adverse-risk AML. MRD negativity is widely accepted as a predictive and prognostic marker for disease-free survival and overall survival. However, the clinical use of MRD status in consolidative HCT planning remains unclear. Methods: Two hundred thirty-three consecutive patients achieving complete remission (CR) as defined in ELN 2022 after receiving therapy at Massey Cancer Center were analyzed. MRD status was determined either by multiparameter flow cytometry, PCR-based sequencing, and/or next-generation sequencing. Patients were analyzed via retrospective chart review to obtain baseline characteristics, molecular and cytogenetic profiles, and survival data. Median overall survival (mOS) was calculated and compared using the Kaplan-Meier method. Continuous variables were compared using one-way ANOVA. Categorical variables were analyzed using Fisher's exact test. Results: In total,109 patients achieved MRD-negative CR and 124 patients achieved an MRD-positive CR. Of the MRD-negative patients, 42 went received HCT (39%). In the MRD-positive cohort, 44 underwent HCT (35%). Among the MRD negative group, those receiving HCT tended to be younger (52.1 y. [range: 24.8-71.7] vs 61. 8 y. (range: 27.1-82.9) p = 0.026) with fewer co-morbidities (Charlson comorbidity index [CCI] score: 3 [range: 2-9] vs 4 (range: 0-14), p = 0.322). We observed a similar trend in those who had MRD positivity at best response or at the time of transplant (age 55 y. [range: 24.5-72.2] vs 62 y. [range: 25.1-88], p = 0.142; CCI 4 [range: 2-7] vs 5 (range 2-11], p = 0.014). In the MRD-negative/no HCT group, 49.3% had ELN favorable-risk disease at initial AML diagnosis, 28.4% had intermediate risk, and 22.4% had adverse risk. In the MRD-negative/HCT group, 31% were favorable risk, 33.3% intermediate risk, and 35.7% were adverse risk. In the MRD-positive/HCT group, 46.3% favorable risk, 23.8% intermediate risk, and 29.5% were adverse risk. There were no significant differences in ELN risk between any group. MRD-positive patients who underwent HCT had a mOS of 25.7 m. vs 20.7 m. for no HCT (HR=0.68 [95% CI, 0.41-1.11], p = 0.125). The median OS was not reached for MRD-negative patients, regardless of receipt of HCT (HR=0.61 [95% CI, 0.30-1.23], p = 0.168). Patients undergoing HCT in MRD-negative CR had improved OS compared to those undergoing HCT with persistent MRD positivity (p = 0.006). Discussion: MRD positivity is a known predictor of relapse and decreased survival despite HCT. However, the use of MRD as a decision point predicting which patients will benefit from transplant a priori needs to be better understood. Our data suggest that MRD negativity has a more significant impact on overall prognosis than HCT status.Likewise, the negative impact of MRD positivity was not significantly abrogated by subsequent HCT. This highlights the need for refinement in HCT selection beyond ELN 2022 intermediate/adverse-risk patients, and new validated algorithms incorporating MRD status are warranted.

Prognostic Value of Measurable Residual Disease in High-Risk Myelodysplastic Syndromes with Intensive Chemotherapy Treatment: Analysis of HOVON-SAKK Studies

Diagnosis of myelodysplastic syndromes (MDS) and accurate risk assessment to tailor treatment remains challenging. High-risk MDS (hrMDS) patients who are fit enough may benefit from intensive chemotherapy followed by post-remission consolidation. The HOVON-SAKK (HO) acute myeloid leukemia (AML) trials, designed to test novel drug combinations with an intensive treatment regimen, included hrMDS patients (RAEB and RAEB-T). Since these HO-trials have been executed with large patient cohorts for many years, they offer the unique possibility to study the outcome, risk classification, and relevance of measurable residual disease (MRD) in hrMDS. A pooled database is available from HOVON-SAKK of patients who were treated with intensive chemotherapy (studies containing MDS patients with IPSS ≥ 1.5 HO42A, HO81, HO92, HO102, and IPSS-R &amp;gt; 4.5 HO103, HO132). The database contained 3268 patients; 11% (364/3268) were hrMDS scored according to IPSS and IPPS-R. Three-year overall survival (OS) for hrMDS was 32% (standard error; SE 2%) compared to AML 46% (SE 1%). In total, 1074 AML and 75 hrMDS had reached complete remission (CR/CRi) and received a second induction cycle (C2). MRD after C2 based on multiparameter flow cytometry (Cloos et al., 2018, J. Vis.) with a cut-off of ≥0.1% for MRD positivity was assessed to evaluate the MRD status. We observed a trend of a higher MRD positivity rate for MDS compared to AML patients (MDS vs. AML: 32% (23/73) vs. 22% (232/1064), P = 0.055). Kaplan-Meier OS analysis showed a significant prognostic value of MRD in MDS, but not in the cumulative incidence of relapse (CIR) (log-rank test 0.011, Gray's test P = 0.124). Since the MDS classification has been changed, we re-classified MDS based on the ICC 2022 classification into AML, AML/MDS, and MDS. We reclassified 3035 patients at diagnosis, including 2605 AML, 258 MDS/AML, and 172 MDS. The three-year OS was 47% (SE 1%) for AML, 29% (SE 3%) for MDS/AML, and 33% (SE 4%) for MDS. After C2, 2215 patients had reached CR/CRi. A total of 1074 patients containing 984 AML, 57 AML/MDS, and 33 high-risk MDS patients with CR/CRi after C2, with a suitable bone marrow sample, were included in the MRD analysis. Most patients were treated according to HO132 (40-48%). As expected, MDS patients were older (median age, range; 60, 32-74), had lower bone marrow blast counts, and were predominantly of adverse risk. A trend of a higher proportion of MRD positivity after C2 was observed in the MDS group (33%; 11/33) as compared to AML (22%; 215/984) or MDS/AML (18%; 10/57). Three-year OS was 61% for AML (SE 1.6%), 42% (SE 6.6%), and 49% (8.7%) for AML/MDS and MDS, respectively (Figure 1A). Kaplan-Meier OS analysis and CIR showed a significant prognostic value of MRD for MDS (log-rank test P&amp;lt;0.001, Gray's test P = 0.015) and AML ( P&amp;lt;0.001; P&amp;lt;0.001) but not for MDS/AML patients ( P = 0.5, P = 0.342)(Figure 1B). Remarkably, the three-year OS of MRDpos in MDS was 18% (SE 12%) compared to MRDpos in AML 40% (SE 16%). The limitation of this study is the relatively small number of MDS patients according to the new ICC 2022 guidelines. In summary, MRD detection in the HOVON-SAKK trials shows the potential of MRD as a prognostic value in MDS patients treated on intensive induction regimens with a clinically validated and standardized assay.

Total Marrow and Lymphoid Irradiation (TMLI) -Based Conditioning Regimen in Patients with Acute Leukemia Undergoing Allogeneic Hematopoietic Cell Transplant with Measurable Residual Disease

Relapse of primary hematologic malignancy remains the leading cause of treatment failure afterallogeneic Hematopoietic cell transplantation (allo-HCT). Multiple studies have shown that presence of measurable residual disease (MRD), at the time of HCT, irrespective of the detection method, is associated with lower overall survival (OS) and relapse-free survival (RFS). In a recent meta-analysis of 11,151 patients with AML, Short et al., reported 5-year disease-free survival (DFS) of 25% for patients who have detectable MRD pre -HCT, compared to 64% for those without MRD. The 5-year OS was 34% and 68% for patients with or without MRD at HCT (JAMA Oncology 2020). In AML patients with genomic evidence of MRD before allo-HCT, myeloablative conditioning (MAC) regimens result in improved survival when compared to reduced intensity conditioning (RIC); (Hourigan et al, JCO 2020). Our center has pioneered and developed Total marrow and lymphoid irradiation (TMLI) that allows for delivery of higher dose of radiation to the sites with high disease burden (bone marrow and lymphoid organs), while sparing healthy tissues. In an ongoing Phase 2 trial (NCT02094794), we delivered TMLI (20Gy) with high dose chemotherapy to patients with high-risk leukemias (ALL or AML) undergoing allo-HCT from an HLA matched or mismatched donor. Here, we report on the results of our prospective analysis on a subset of patients of NCT02094794 who underwent allo-HCT with morphologic remission but had detectable MRD status in their pre HCT bone marrow biopsy (n=30). Conditioning regimen comprised of TMLI on days -9 to -5 (total of 20Gy), etoposide (60 mg/kg) on day -4, and cyclophosphamide (100mg/kg) on day -2. Unmanipulated peripheral blood stem cells (PBSC) graft from 10/10 HLA matched related or unrelated donor was infused on day 0 and graft-versus-host disease (GVHD) prophylaxis was tacrolimus and sirolimus-based. TMLI was delivered by intensity modulated radiation therapy (IMRT). MRD assay was done by either University of Washington flow cytometry with 0.01% - 0.1 % sensitivity, FISH/conventional cytogenetics, or NGS-based assays. Patient and HCT characteristics are summarized in Table 1. Briefly, the median age at the time of HCT was 36 years (range: 16-59) with the majority of patients receiving PBSC grafts (87%). Donors were match related (67%) or match unrelated (33%). The underlying diagnosis was AML (n=22; 73%), ALL (n=7; 23%), or CML-BC (n=1; 3%). Karnofsky performance status was 80-100 in 90% of patients and HCT-CI ≥3 was seen in 35% of patients. Pre-HCT MRD + status was documented by Flow cytometry MRD assay in 17 patients [AML (n=14) and ALL (n=3)], with mean MRD positivity of 2.9 % (range: 0.02-5.6%) for AML and 0.4% (range: 0.003-1.7%) for ALL patients. Thirteen additional patients had MRD positive status confirmed by FISH/cytogenetics (n=6 patients) or NGS (n=7). With a median duration follow up of 22.3 months (range: 6.0-81.1), the 1 and 2-year OS were 68% (95% CI: 0.47-0.82) and 59% (95% CI: 0.38-0.75), respectively. The 1 and 2- year disease-free survival (DFS) were 55% (95% CI: 0.34-0.71) and 45% (95% CI: 0.26-0.63), while the cumulative incidence (CI) of relapse at 1 and 2 years were 28% (95% CI: 0.13-0.46) and 33% (95% CI: 0.16-0.51), respectively. At day 100 post-HCT, the CI of NRM was 7%, grade 2-4 acute GVHD was 40% and Grade 3-4 acute GVHD was 13%. The CI of NIH moderate- severe chronic GVHD at 1- year was 35% (95% CI: 0.17-0.52). No difference in outcomes were noted in patients who were MRD positive by UWFC vs FISH/NGS testing. In conclusion, TMLI based conditioning regimen in patients undergoing allo-HCT with MRD+ disease from matched donors is associated with improvement in 2-year RFS/OS and is associated with low NRM compared to historic controls. The current phase 2 study is enrolling patients at our center.

The Laip-Based-Dfn Approach Is Superior in Terms of Useful MRD Results As Compared to the Laip Approach after Cycle II in Acute Myeloid Leukemia

Clinical decision-making based on measurable residual disease (MRD) in acute myeloid leukemia (AML) is steadily increasing; therefore, accurate MRD results are imperative. Multi-parameter flow cytometry (MFC) is often used due to wide availability, particularly when no suitable mutation is present. Two approaches are most common in MFC-MRD: 1. Leukemia-associated immunophenotype (LAIP) approach, in which the aberrant phenotype is identified at diagnosis and tracked during follow-up. 2. Different-from-Normal (DfN) approach, in which aberrant surface antigen expression patterns not present in normal bone marrow (empty spaces in 2D dot plots) are identified at follow-up. The LAIP approach is sensitive, but does not consider immunophenotypic shifts and cannot be used when no LAIP is identified at diagnosis or when a diagnosis sample is unavailable. The DfN approach can detect these shifts, but ample expertise is needed to determine a malignant population. In the ELN-DAVID AML-MRD guidelines 2022, it is recommended to use the combination of the LAIP approach and the DfN approach to use the advantages of both approaches. In the HOVON-SAKK132 (HO132), the MRD was based on the combination of MFC-MRD and NPM1 RQ-PCR. Initially, the MFC-MRD in this study was based on the LAIP approach. However, the complete MFC panel (four 8-color tubes) published by Cloos et al. (J.Vis.Exp, 2018) was used for measuring MRD during follow-up. Therefore in this study, we had the unique opportunity to retrospectively analyze the samples after induction cycle 2 (C2) of patients in complete remission (CR/CRi) and determine additional MRD results with the LAIP-based-DfN approach. The original LAIP approach encompasses determining the percentages of the LAIPs in the follow-up sample, which were also identified at diagnosis. For the LAIP-based-DfN approach, we followed the same approach, but determined the percentages of all possible LAIPs in the MFC-MRD panel at diagnosis and after C2. An emerging LAIP is defined as a LAIP that is present in the follow-up but was not found at diagnosis. MRD positivity was defined as ≥ 0.1% LAIP cells of white blood cells. Patients with an emerging LAIP &amp;lt; 0.1% or no LAIPs in follow-up would result in MRD negativity for LAIP-based-DfN, but was only possible when at least 500,000 cells were acquired in all four tubes. At diagnosis, we received 884 samples of 905 patients (98%), in which we found a LAIP ≥ 10% of CD45dim blasts in 83% of the samples (Figure 1A). After C2, we received 615 samples, for which we had MFC-MRD results for 79% (487/615) by the LAIP approach. When we applied the LAIP-based-DfN approach, we scored 69 of 615 extra MRD results: an emerging LAIP ≥ 0.1% (MRDpos, N = 14), no LAIPs (MRDneg, N = 25) or an emerging LAIP &amp;lt; 0.1% (MRDneg, N = 30). When including these results in the data of the LAIP approach, the percentage of patients with an MRD result increased from 79% (487/615) to 90% (556/615), and the MRD positive percentage increased from 13% (81/615) to 19% (118/615)(Figure 1B). The LAIPs of emerging clones most often included CD56, CD15, and CD22. To assess the prognostic value in the HO132, we combined the reanalyzed LAIP-based-DfN MFC-MRD with the NPM1-MRD (N = 567). In these analyses, overall survival (OS) hazard ratio (HR) 95% confidence interval (CI) 1.92 (1.44-2.56) and relapse-free survival (RFS) HR 95% CI 1.7 (1.31-2.19) were similar to the original LAIP based/ NPM1 approach: OS HR: 95%CI 2.02 (1.48-2.76) and RFS HR: 95%CI 1.78 (1.34-2.35), respectively. In conclusion, the LAIP-based-DfN approach adds additional MRD results while retaining the prognostic value. Since HOVON-SAKK centers are highly compliant with the protocol and 98% of diagnosis samples were available, the LAIP-based-DfN approach can offer additional value for studies with limited access to diagnosis samples.

Impact of High-Risk Cytogenetics (HR-CTG) on the Outcome of Newly Diagnosed Adult Patients with Philadelphia Negative B-Cell Acute Lymphoblastic Leukemia (B-ALL) Treated with Frontline Blinatumomab (Blina) and/or Inotuzumab Ozogamicin (Ino) Containing Hypercvad (HCVAD) Therapy

Introduction: HR-CTG in B-ALL is considered an adverse prognostic factor along with age and measurable residual disease (MRD) status. The use of potent B-cell targeted drugs like InO and Blina as part of frontline therapy has improved outcomes in adult pts with B-ALL ( Jabbour et al, Lancet Haematology 2022 and 2023) but the impact of baseline HR-CTG needs to be further elucidated . Methods: From Oct 2014-Feb 2023 we identified 71 consecutive patients (pts) with Philadelphia (Ph)-negative B-ALL and adequate CTG data who were treated on frontline therapy that included InO and/or Blina along with HCVAD chemotherapy. The intensive phase of treatment protocol consisted of HCVAD 4 courses followed by 4 courses of blina which could be initiated post HCVAD course 2 for high-risk or MRD positive pts and has been published before (Jabbour et al, Lancet Haematology 2022). The protocol was later amended to include fractionated InO from course 2 of HCVAD at a cumulative dose of 2.4 mg/m 2(Short et al, ASCO 2023). Pts with confirmed Ph-like ALL were excluded. CTG was evaluated and graded as HR based on a combination of conventional karyotyping and fluorescent in situ hybridization data and included low-hypoploidy or near triploidy (Ho-Tr), complex karyotype (CK; ≥5 abnormalities), 14q32 rearrangement ( IGH) and KMT2A re-arrangement as described before (Issa et al, Cancer 2017). Results: 31 of 71 pts (44%) with Ph- B-ALL had HR-CTG; 14 pts (45%) with Ho-Tr, 8 (26%) pts with KMT2A rearrangement, 6 pts (19%) with CK and 3 pts (10%) with IGH rearrangement (Table 1). The median age of the whole cohort was 33 years (range, 18-60 years); median age was 29 yrs in HR-CTG group compared to 34 yrs in non-HR-CTG group. 12 pts (39%) in the HR group compared to 5 pts (12%) in the non-HR group had a TP53 mutation ( p=0.01). 5/12 (42%) pts in the HR group with TP53 mutation had low-hypoploidy. 7 pts (23%) and 13 (32%) pts in the HR-CTG and non-HR-CTG group respectively had RAS mutations, with 1 pt in each group having both TP53 and RAS mutation. 17 pts (55%) received Blina and 14 pts (45%) received both InO and Blina in the HR group compared to 20 pts (50%) each who received Blina and Blina+ InO in the non-HR group. A best response of complete remission (CR)/CR with incomplete count recovery (CRi) was obtained in 100% pts (CR=30, CRi=1) in the HR-CTG group, 17 (55%) of whom had concurrent MRD negativity ; in the non-HR-CTG group 39 pts (98%) attained CR and one pt a partial remission, with concurrent MRD negativity attained in 21/39 (54%) pts with CR. At a median follow-up of 31 months (mos) for the full cohort (43 mos for HR pts and 28 mos for the non-HR group) the median overall survival (OS) was not reached (NR) and 3-yr OS was 85% (95% CI, 78-92%); median OS and 3-yr OS were NR and 89% in the HR-CTG group and 74.7 mos and 82% in the non-HR-CTG group ( p=0.64). The median relapse free survival (RFS) was NR in the HR-CTG group and 74 mos in the non-HR group ( p=0.73) while the 3-yr RFS were 74% and 80% respectively. There was no intergroup difference in RFS and OS based on the MRD status at response assessment. 11 HR-CTG pts (35%) underwent allogeneic stem cell transplantation (SCT) (5 Ho-Tr, 4 KMT2Ar, 1 CK, 1 IGHr) in continued remission at a median of 4.8 mos from therapy initiation (IQR 4.5-8.2 mos), 9 of whom went directly to SCT without introduction of a new therapy between the frontline therapy and SCT. Two pts received additional lines of therapy for MRD relapse/progression without morphological relapse before SCT. The 3-year OS in the HR-CTG pts who underwent SCT was 87% and similar to HR pts who did not undergo SCT (89%, p=0.78). 5 pts (12%) underwent SCT in the non-HR-CTG group, 4 for persistent or recurrent MRD positivity and one with Down's syndrome. No pts in either groups developed hepatic sinusoidal obstruction syndrome or a secondary myeloid neoplasm. Conclusion: In our analysis, in a prospectively maintained dataset where &amp;gt;90% pts were treated on clinical trial, HR-CTG did not have any significant impact on B-ALL survival outcomes when treated with frontline therapy containing B-cell targeted agents. Further analysis is underway.

Pediatric Patients with Acute Lymphoblastic Leukemia Treated with Blinatumomab in a Real-World Study

Introduction Pediatric B-cell acute lymphoblastic leukemia (B-ALL) involves chromosomal abnormalities and genetic alterations at an early stage of differentiation of lymphoid precursor cells. Most children (~around 80%) with B-ALL can achieve long-term survival with conventional chemotherapy but a sizable number of patients relapse or do not attain complete remission. Blinatumomab is a bispecific T-cell engager antibody designed to redirect CD3+ T cells to bind to CD19+ target cells. Although blinatumomab has been approved for the treatment of relapsed or refractory B-ALL, it has shown efficacy in newly diagnosed B-ALL also. Here, we studied the effect of blinatumomab in newly diagnosed B-ALL (including infantile B-ALL) and post-induction therapy measurable residual disease (MRD) positive B-ALL in a real-world study. Methods Pediatric patients with B-ALL including newly diagnosed infants (infantile type) or with MRD positivity during the induction remission phase, were enrolled. The patients received a 7-day pre-treatment VCP regimen consisting of intravenous infusions of cyclophosphamide 800 mg/m 2 on day 1, vindesine 3 mg/m 2 on day 1, prednisone 1-2 mg/kg on days 1 to 7 (VCP regimen), followed by 28 days of treatment with blinatumomab at 5µg/m 2/day on the first 1 to 7 days and 15 µg/m 2/day on the next 8 to 28 days. Four patients with economic burden received blinatumomab for 14 days: 5µg/m 2/day for days 1 to 4 and 15 µg/m 2/day from day 5 to 14, after pre-treatment with the VCP regimen. Bone marrow assessment of MRD was done on days 14 and 28. Results Between July 2022 and July 2023, 24 pediatric patients received VCP-blinatumomab. Among them, 11 (45.8%) patients had high-risk disease, and 5 (20.8%) had standard risk. The median age of the cohort was 8.5 years. Among the cohort, there was 1 patient with infantile B-ALL and 1 patient with Philadelphia chromosome-positive (Ph+)-ALL; besides 3 patients were TEL-AML positive, 3 patients were CRLF2 positive, 1 patient was E2A-PBX1 positive, 1 patient was SSBP2-CSF1R positive, and 1 patient was EVI1 positive. Blinatumomab was administered to 5 patients in the induction remission period, and for 2 patients, blinatumomab was administered in consolidation after inotuzumab ozogamicin (INO). While 18 patients were treated with blinatumomab for 28 days, 6 patients were treated with blinatumomab for 14 days. Four patients opted for a 14-day regimen due to financial reasons and 2 patients were transplanted with hematopoietic stem cell transplantation after 14 days of treatment with blinatumomab. All the treated patients achieved MRD negativity (100%). There were no ≥ grade 3 treatment-related toxicity and no deaths reported. Conclusion Our study results showed that a 100% MRD negativity rate was achieved in children with B-ALL after treatment with the blinatumomab consolidation following the chemotherapy and no significant safety concerns were observed. Blinatumomab consolidation therapy was also effective in patients pretreated with INO. Blinatumomab consolidation after induction therapy could be a new and effective strategy for the treatment of patients with newly diagnosed B-ALL.

Measurable Residual Disease Status By Clonotypic Mass Spectrometry with Easym Assay Predicts Outcomes Following Autologous Hematopoietic Cell Transplant in Multiple Myeloma

Bone marrow (BM)-based measurable residual disease (MRD) has been established as one of the most important dynamic prognostic markers in multiple myeloma (MM). However, the necessity of bone marrow biopsies limits the feasibility of frequent MRD monitoring. Consequently, there is an urgent unmet need for peripheral blood-based MRD testing for serial monitoring of disease response to allow tailored therapy for patients achieving deep remissions. Quantification of myeloma (M)-protein using mass spectrometry (MS) is a promising approach for peripheral blood-based MRD monitoring due to its exceptional analytical sensitivity. Prior studies have examined the use of MALDI-TOF-based methods, which relies on the mass distribution of intact immunoglobulins light chains and is approximately 1-log more sensitive than traditional testing. However, recent advances in MS technology have allowed determination and tracking of a “clonotypic” MS signature in the peripheral blood which is highly sensitive and patient-specific (Liyasova et al, CCR 2021). Prior reports have demonstrated the feasibility of this approach, but data supporting the association of blood-based clonotypic MS MRD with clinical outcomes is currently lacking. Consequently, we performed a large retrospective analysis of patients enrolled in our institutional MM tissue bank to determine the association of clinical outcomes with clonotypic MS-based MRD testing (EasyM, Rapid Novor, Kitchener, ON). We identified patients in our institutional tissue bank who met the following criteria: 1) diagnosis of MM, 2) underwent autologous hematopoietic cell transplant (AHCT), 3) M-protein ≥0.2 g/dL by serum protein electrophoresis (SPEP) or &amp;gt;20 mg/dL (light chain) at diagnosis, 4) had no detectable M-protein by SPEP at day +100 and 5) had adequate samples for analysis collected at day +100 after AHCT. Patients were included regardless of M-protein isotype. Baseline and follow up samples were analyzed by Rapid Novor without access to the clinical outcomes. Percent residual EasyM at day +100, in respect to baseline EasyM, was used as the independent variable to predict Progression-free survival (PFS). 95 patients were included in the analysis. Median age was 63, 88% were White and 61% were male. 64% were IgG, 20% IgA and 16% were with light chain (LC) MM. 26%, 62% and 12% were R-ISS stage I, II and III, respectively. High-risk cytogenetics were present in 32%. 97% had received proteasome inhibitors, 89% received immunodulatory agents and 13% anti-CD38 antibodies prior to AHCT. The median year of transplant was 2018 (range: 2008 - 2022). 93% patients received AHCT as part of frontline therapy. 66% were in CR or better following AHCT. 95% received maintenance after AHCT. 9 patients had non-quantifiable EasyM at follow up and were excluded from derivation of the MRD definition. Of the remaining 86, patients with IgA/LC and IgG disease had significant different percent residual EasyM following AHCT (median: 0.19% vs. 1.00%, p &amp;lt; 0.001). A cutoff of 1.036% residual EasyM was derived for IgG and 0.048% residual EasyM for IgA/LC patients was determined to fit the PFS data best, and based on these cutoffs, 41 patients (47%) were MRD negative by EasyM. The incidence of MRD negativity between IgG and IgA/LC was similar (55% vs. 32%). MRD positivity by EasyM was a strong predictor of PFS following AHCT (Figure 1) (HR: 2.249, p = 0.017). The median PFS in MRD positive patients was 3.4 years versus not reached in MRD negative patients (log rank: p = 0.014) (Figure 1). Our study is the first, to our knowledge, to demonstrate the clinical utility of peripheral blood-based clonotypic mass spectrometry to predict outcomes for patients with MM. Notably, our results suggest that different cutoffs should be employed for IgG and IgA/LC myeloma if drawn at day +100 after transplant. This is possibly due to the differing half-lives of these molecules. Significant additional questions remain, including the utility of ongoing monitoring at multiple time points and the optimal time post-AHCT to assess for MRD, especially in patients with IgG myeloma. Additionally, these findings require prospective validation in an independent cohort of patients to demonstrate wider applicability.

Discordance between Next Generation Sequencing and BCR-ABL PCR Measurable Residual Disease in Adult Patients with Ph+ Acute Lymphoblastic Leukemia

Background: It remains unclear whether measurable residual disease (MRD) detected by next-generation sequencing (NGS) or BCR-ABL RT-PCR is more accurate in predicting relapse and guiding clinical management in patients with Ph+ acute lymphoblastic leukemia (ALL). In this multi-center retrospective study, we examine the discordance between BCR-ABL PCR and NGS MRD to better characterize practice patterns for disease monitoring for patients with Ph+ ALL. Methods: We included Ph+ ALL patients from five academic hospitals in the United States who were monitored with both BCR-ABL PCR and NGS-based clonoSEQ (Adaptive Biotechnologies) between 2015 and 2023. Patients were included if they had both baseline BCR-ABL PCR and NGS MRD assessments and at least 1 follow-up MRD assessment using both modalities. BCR-ABL PCR and NGS MRD results were only included if they were taken less than 1 month apart. Patient demographics, BCR-ABL isoform (p190 or p210), and IKZF1, CDK2NA, and PAX5 copy number alterations were also collected. We used frequency counts, median, and interquartile range (IQR) to describe our data. Univariable logistic regression was performed to quantify associations between diagnostic patient features and any post-diagnosis MRD discrepancy (i.e., MRD positive vs. MRD negative) between the two modalities. Results: 93 patients had both BCR-ABL PCR (p190 n=61 [66%], p210 n=21 [23%], both n=8 [9%]) and NGS MRD assessments. Descriptive statistics are shown in Table 1. Figure 1 is a Sankey diagram illustrating the trajectory of BCR-ABL PCR and NGS concordance at 3, 6, and 12 months following diagnosis. 60 patients (64%) had a discrepancy between qPCR and NGS at any time after Ph+ ALL diagnosis while 24 patients (26%) had a discrepancy within the first 3 months. For the 54 patients (58%) receiving transplant, 38 (70.4%) had a post-diagnosis MRD discrepancy. Among all patients, median time from diagnosis to first discrepancy was 3.9 (IQR, 2.3-7.3) months. The most common discrepancy was BCR-ABL PCR detectable / NGS undetectable (n=39, 42% of included patients). In 12 patients (20% of patients with an MRD discrepancy at any time), clinical decision making was changed due to this observed discrepancy in MRD status. While a persistently positive PCR result with negative NGS led to a change in treatment regimen for 8 of these patients (75%), one patient's positive PCR with negative NGS led to the decision to continue current therapy. Further, a positive NGS with negative PCR led to change of treatment in 3 patients. BCR-ABL isoform and copy number variation of target genes were not associated with increased risk of MRD discrepancy, although sample size was limited for the genetic alterations (Table 1). Conclusion: We found a considerable degree of discordance between BCR-ABL PCR and NGS in Ph+ ALL patients. The most common discrepancy was PCR detectable / NGS undetectable, and in case of discordance, PCR positive results are most frequently given precedence in guiding clinical management. In the discordant patients, the presence of MRD positivity via either test drove changes to treatment rather than MRD negativity in one of the two tests. Future studies should investigate whether BCR-ABL PCR or NGS is a better predictor of outcome in Ph+ ALL.

Prospective Evaluation of Measurable Residual Disease (MRD) and Sustainability of the Response in Patients with Systemic AL Amyloidosis Treated with Daratumumab

Background: Daratumumab can provide deep hematologic responses for patients with light chain (AL) amyloidosis, both through its direct anti-clonal activity and immunomodulatory effects on other cell populations in the bone marrow (BM) microenvironment. Promising efficacy in the frontline setting when combined with CyBorD (per the ANDROMEDA trial), as well as in the relapsed/refractory setting as monotherapy, has led to daratumumab becoming the first FDA-approved therapy for AL amyloidosis. Though it is administered for up to 24 cycles, the optimal duration of treatment is unclear. Dynamic monitoring of measurable residual disease (MRD) may provide insights into changes in the aberrant plasma cell (PC) clone and sustainability of the hematologic response in relation to daratumumab therapy. Aims: We sought to evaluate the rates of MRD clearance and resurgence both during and after daratumumab therapy for AL amyloidosis. Methods: MRD status was assessed for patients followed at the Boston University Amyloidosis Center, who were treated with a daratumumab-based regimen and achieved a hematologic very good partial response (hemVGPR) or complete response (hemCR) according to consensus criteria (Palladini, 2012). MRD assessments were performed by multiparametric 10-color flow cytometry of BM aspirates (sensitivity level of ≤10 -5) and repeated at 12-month intervals during follow-up. Clonal progression was defined as growth in the aberrant PC clone size of &amp;gt;1-log. Results: Between 2019 and 2023, a total of 66 patients achieved ≥hemVGPR and were tested for MRD; 43 (65%) received daratumumab monotherapy in the relapsed/refractory setting and 23 (35%) in combination with CyBorD as frontline therapy. Collectively, 48 (73%) achieved a hemCR and 18 (27%) a hemVGPR. The median age at diagnosis was 60 years (range 35-78); 19 (29%) patients were female; and 11 (17%) identified as non-white race. MRD assessment was performed once, twice or ≥3 times for 33, 18 and 15 patients, respectively. The first MRD evaluation occurred while still receiving daratumumab for 33 patients (at median 12 cycles, range 6-23); the remaining patients had their first MRD evaluation after therapy completion (median one month after, range 0-25). Of the entire cohort, 28 (42%) patients achieved MRD negativity and 38 (58%) MRD positivity (median estimated aberrant PC clone size 1.5 x 10 -4, range 1.4 x 10 -5 to 1.1 x 10 -2, representing 46.9% ± 32.8% of total PCs) at first evaluation. All but one patient with a hemVGPR had detectable MRD. Of the 23 patients who received frontline daratumumab-CyBorD (18 hemCR and 5 hemVGPR), 8 (35%) achieved MRD negativity at first evaluation; whereas 20 (47%) of the 43 patients who received daratumumab as monotherapy (30 hemCR and 13 hemVGPR) achieved MRD negativity. We surveyed MRD profiles based on the number of daratumumab treatment cycles received (Table 1) and found no apparent patterns with increasing cycles. Serial MRD monitoring was performed for 33 patients (Figure 1). Of 10 patients who continued to receive daratumumab between MRD assessments (group 1), 6 had sustained MRD negativity; 2 had persistent MRD positivity (of whom one had clonal progression); and 2 had MRD clearance (conversion from positive to negative). Of 23 patients who underwent serial MRD assessments after completing daratumumab (group 2), 9 (39%) had sustained MRD negativity; 10 (43%) had persistent MRD positivity; 2 (9%) had MRD clearance; and 2 (9%) had MRD resurgence (conversion from negative to positive), which occurred 17 and 26 months after daratumumab cessation. Clonal progression was observed in 5 of the 10 patients with persistent positivity, of whom 3 experienced a hematologic relapse. Conclusions: Our findings show that patients with AL amyloidosis can attain deep responses with daratumumab-based treatments, even to the depth of undetectable MRD. Clearance of MRD was frequent not only during treatment with daratumumab but also after completion of therapy, suggesting continuing effects on the plasma cell clone. Clonal progression after daratumumab completion was often associated with hematologic relapse. Prospective studies are needed to investigate whether daratumumab may be stopped early for those with undetectable MRD, or whether those with persistent detectable disease may benefit from extending daratumumab treatment beyond 24 cycles.

Measurable Residual Disease Assessment in Patients with Acute Myeloid Leukemia Aged ≥60 Years Treated with a 10-Day Decitabine Schedule Versus Intensive Chemotherapy in the AML21 Study (NCT02172872)

Introduction Several studies have demonstrated that patients with acute myeloid leukemia (AML) who test measurable residual disease (MRD) positive during or after treatment have a higher probability of relapse and a shorter duration of survival, as compared to those who are persistently MRD negative. Indeed, a status of MRD positivity reflects a condition of resistant disease, existing below the threshold of the morphologic evaluation of complete remission (CR). The bulk of our knowledge in terms of MRD assessment has been generated in the setting of intensive chemotherapy; much less is known for older patients receiving less intensive treatments, such as decitabine (DEC) using a 10-day schedule. Methods The AML21 study was a randomized open-label phase 3 clinical trial conducted by the EORTC Leukemia Group, GIMEMA, and GMDS-SG. Patients with a newly diagnosed AML, aged ≥60 years and eligible for intensive chemotherapy were randomized 1:1 to receive DEC (20mg/m2 a day) using a 10-day schedule or intensive chemotherapy regimen consisting of daunorubicin 60 mg/m2 x 3 days and cytarabine 200 mg/m2 x 7 days (3+7), followed by 1-4 additional chemotherapy cycles. Patients who had an HLA-matched donor and at least stable disease were encouraged to undergo HSCT after &amp;gt;1 treatment cycle. Patients from the DEC arm not receiving HSCT could continue DEC treatment. A subset of patients treated in GIMEMA sites underwent a prospectively planned MRD evaluation post cycle 3 (DEC arm)/post consolidation (3+7 arm), and at 6, 12 and 18 months after the randomization, in case they were in a first CR and had not been allografted. MRD was studied by multiparameter flow cytometry. Based on several retrospective validations in the context of former EORTC/GIMEMA protocols, the threshold for discriminating MRD negative from MRD positive cases was set at 3.5x10-4 (0.035%) residual leukemic cells, upon full blood count recovery. Results In total, 130 out of 154 patients treated in GIMEMA centers provided consent for participation in translational research, had leukemia associated immunophenotype suitable for MRD monitoring, and initiated the protocol treatment, DEC (N=66) or 3+7 (N=64). Median age was 68 years (range 60-78), 33% of patients were ≥70 years old, 54% were male, and 31% and 30% had good and adverse European LeukemiaNet 2017 risk profile, respectively. At the MRD evaluation post cycle 3/consolidation, 9 out of 66 (14%) patients from the DEC and 12 out of 64 (19%) patients from the 3+7 arm had documented MRD negativity. The number of patients who either had documented MRD negativity or had undergone allografting and were alive and progression-free was 12 (18%) and 17 (27%) at 6 months, 14 (21%) and 13 (20%) at 12 months, and 14 (21%) and 7 (11%) at 18 months in the DEC and 3+7 arms, respectively. The inspection of individual profiles of patients who underwent the first MRD evaluation (and were at remission at that time) indicated that all MRD-positive patients from the DEC arm who were not allografted eventually relapsed, which often occurred just after the discontinuation of DEC maintenance. Conclusions 10-day DEC treatment can induce MRD-negativity. However, early MRD-negativity appeared more difficult to achieve with 10-day DEC than with 3+7. Among patients in whom 10-day DEC did not induce MRD-negativity, allografting or DEC maintenance appeared necessary to avoid a disease relapse.