Measurable Residual Disease Status Research Articles

Association of Measurable Residual Disease with Progression-Free Survival in Patients with Chronic Lymphocytic Leukemia: A Systematic Review and Meta-Analysis in the Era of Novel Agents

Introduction: Achieving undetectable measurable residual disease (uMRD) following treatment has shown significant prognostic value in several hematological malignancies. In chronic lymphocytic leukemia (CLL), uMRD is associated with improved outcomes in the era of chemoimmunotherapy (CIT). However, the role of measurable residual disease (MRD) in the context of novel agents such as Bruton tyrosine kinase inhibitors (BTKi) and/or BCL2 inhibitors (e.g. venetoclax) is uncertain. To address this question, we conducted a systematic review of the literature and performed a comprehensive meta-analysis of trials that included novel agents to evaluate the association between MRD status after treatment and PFS in patients with CLL. Methods: We conducted a comprehensive search of PubMed, EMBASE, Scopus, and Web of Science focusing on CLL trials reporting MRD and its association with PFS. Results were independently screened by two reviewers. Inclusion criteria included prospective phase 3 trials involving a novel agent in one of the treatment arms, while studies with incomplete information on MRD status related to PFS, reviews, abstracts, and retrospective analyses were excluded. The initial search identified 185 studies in PubMed and 402 studies in EMBASE. After applying prespecified criteria, a total of 10 phase 3 trials were included in our analysis. We extracted sample size, patient age, follow-up time, time point and tissue of MRD assessment, MRD cut-off and rate, performance status and molecular status when available. We only considered treatment arms with complete MRD information. The comparison involved patients who achieved uMRD with those exhibiting detectable MRD. When available, hazard ratios (HR) and confidence intervals (CI) were used to evaluate the relationship between MRD status and PFS. If not, we used Kaplan-Meier (KM) curves from both uMRD and MRD subgroups and extracted the coordinates points of the curves using DigitizeIt software (version 2.5.10, I. Bormann) and using the number at risk provided we estimated the HRs and CIs. A meta-analysis was performed using a random effects model from the R package metafor (Viechtbauer, W. (2010). Conducting meta-analyses in R with the metafor package. Journal of Statistical Software, 36(3), 1-48). The pooled hazard ratio estimates, and the corresponding 95% CI and prediction intervals (PI) were reported. Funnel and Baujat plots were generated to assess study heterogeneity and bias. All analysis was performed using R version 4.1.2 (R Foundation for Statistical Computing, Vienna, Austria). Results: A total of 10 phase 3 trials, encompassing 14 treatment arms and involving 3152 patients, met the stringent inclusion criteria. All but one study used a uMRD cut-off of < 0.01%. Detailed information on the treatment arms and key trial characteristics is presented in Table 1. Notably, ten treatment arms were derived from first-line treatment trials, while the remaining arms pertained to the relapsed/refractory population. Only two trials (4 treatment arms) assessed MRD using next generation sequencing (NGS), while the rest used multicolor flow cytometry (MFC) (9 treatment arms) and allele-specific oligonucleotides polymerase chain reaction (ASO-PCR) (2 treatment arms). All but 3 trials assessed MRD in both bone marrow (BM) and peripheral blood (PB). One trial (2 treatment arms) was excluded from the met-analysis due to higher MRD cut-off. All studies included in the meta-analysis measured uMRD (<0.01) versus MRD. The PFS pooled HR estimate for achieving uMRD at 0.01 cut off from the meta-analysis was 0.32 (95% CI [0.22, 0.45]), with minimal bias observed on the Funnel Plot. Conclusions: In this comprehensive meta-analysis, comprising 9 phase 3 trials, achieving uMRD was strongly associated with PFS. These findings further establish the prognostic role of MRD in CLL management and its potential use as a surrogate marker in clinical trials. As the body of evidence on MRD in CLL continues to grow, it becomes imperative to standardize the optimal time point, methodology, and tissue for MRD assessment. Substantial heterogeneity in these aspects underscores the necessity for unified guidelines to ensure the accurate and consistent evaluation of MRD status in clinical practice.

Comparison of Autologous, Matched Sibling, and Alternative Donor Stem Cell Transplant Outcomes for Acute Myeloid Leukemia Patients in First Remission: A Propensity Score Matching Study

Introduction Autologous hematopoietic stem cell transplantation (auto-HSCT), matched sibling donor HSCT (MSD-HSCT), and alternative donor HSCT (AD-HSCT) are viable post-remission treatment options for acute myeloid leukemia (AML). Auto-HSCT is more commonly administered in favorable- and intermediate-risk AML with good remission, while MSD-HSCT and AD-HSCT are suggested for patients with high-risk factors. In the present study, we aim to retrospectively compared auto-HSCT with MSD-HSCT and AD-HSCT in de novo AML patients who are in first complete remission (CR1) with favorable or intermediate risk, according to 2022 ELN criteria. Methods We conducted a single-center retrospective comparative analysis, comparing auto-HSCT and allo-HSCT for favorable and intermediate-risk de novo AML in CR1. Patients with secondary AML, acute promyelocytic leukemia, poor-risk AML, those receiving syngeneic HSCT, those not in CR1 before HSCT, or those who achieved CR1 with ≥ 3 cycles of induction chemotherapy were excluded from the study. A total of 283 de novo favorable- and intermediate-risk AML patients, based on the ELN 2022 criteria, in first complete remission were initially included for propensity score matching. Persistent undetectable MRD (uMRD) was defined as uMRD after one course of chemotherapy without recurrent positive MRD before HSCT, while non-persistent uMRD was characterized by the presence of detectable MRD at least once before HSCT. The variables used for propensity score matching included induction chemotherapy cycles, consolidation chemotherapy cycles, and measurable residual disease (MRD) measurement by flow cytometer before HSCT. A caliper width of 0.2 was used. Following the matching process, 126 patients were selected for further analysis, with 42 patients in each of the auto-HSCT, MSD-HSCT, and AD-HSCT groups. Results After applying propensity score matching, a final cohort of 126 patients was available for analysis. This cohort consisted of 42 patients in each group: auto-HSCT, MSD-HSCT, and AD-HSCT. Among the AD-HSCT group, 38 of 42 (90.5%) patients received haploidentical HSCT (haplo-HSCT). All patients received myeloablative conditioning regimen. There were no significant differences observed in the 3-year overall survival (OS) and disease-free survival (DFS) among the auto-HSCT, MSD-HSCT, and AD-HSCT groups [3-year OS: 79.5% (95% CI, 67.8-93.3%), 83.0% (95% CI, 72.2-95.3%), and 65.7% (95% CI, 50.5-85.5%), respectively; P=0.21. 3-year DFS: 72.6% (95% CI, 59.9-87.9%), 83.0% (95% CI, 72.2-95.3%), and 67.5% (95% CI, 54.2-84.1%), respectively; P=0.32]. The cumulative incidence of 3-year NRM was 2.7% (95% CI, 2.0-12.5%), 7.3% (95% CI, 1.8-17.9%), and 21.9% (95% CI, 10.7-35.6%), respectively (P=0.008). The 1-year probability of OS after relapse was higher in the auto-HSCT group (44.4%; 95% CI, 21.4-92.3%) compared with MSD-HSCT (0.0%) and AD-HSCT (37.5%; 95% CI, 8.4-99.9%) (P=0.0017). The MRD status before HSCT had an impact on DFS (persistent uMRD versus non-persistent uMRD: HR=0.29; 95% CI 0.09-0.94, P=0.04) and relapse (persistent uMRD versus non-persistent uMRD: HR=0.17; 95% CI 0.05-0.66, P=0.01) following auto-HSCT. The subgroup analysis was then performed based on MRD status before HSCT. In patients with uMRD before transplant (n=83), OS was similar across the groups. However, auto-HSCT showed a trend of increased DFS compared to AD-HSCT (HR 2.85, P=0.09), resulting in a 3-year DFS and OS of 79.1% and 82.8%, respectively. In the non-persistent uMRD group (n=38), auto-HSCT exhibited a tendency to increase the risk of relapse, particularly when compared to AD-HSCT (HR 0.24, P=0.07), but this did not result in inferior OS. The monthly direct medical cost per patient within the first two years after HSCT was significantly lower in auto-HSCT compared to MSD-HSCT (P=0.015) and AD-HSCT (P<0.001). Conclusions Our results provide evidence for the use of auto-HSCT as a viable therapeutic option for favorable- and intermediate-risk de novo AML patients in first complete remission with persistent uMRD. Additionally, our findings demonstrated a notable cost advantage associated with auto-HSCT compared to MSD-HSCT and AD-HSCT.

A Novel and Cost-Efficient Measurable Residual Disease (MRD) Detection Assay Using a Single Molecule Molecular Inversion Probe-Based Next Generation Sequencing (NGS) Assay Predicts Overall Survival in Patients with Acute Myeloid Leukemia Undergoing Allogeneic Stem Cell Transplantation

Introduction Relapse remains the main reason for poor outcomes of patients (pts) with acute myeloid leukemia (AML). Allogeneic hematopoietic stem cell transplantation (HSCT) is the preferred post-remission treatment in pts at high risk of relapse. The presence of measurable residual disease (MRD) after intensive frontline treatment or before or after HSCT has emerged as an important predictor of relapse. Various methods are used for MRD detection, including flow cytometry and molecular assays detecting individual gene mutations (mut) such as NPM1mut. Next generation sequencing (NGS)-based assays covering multiple genes commonly mutated in AML may allow sensitive MRD detection in a broad range of pts with diverse genetic characteristics. Methods We established a targeted, error corrected NGS MRD assay utilizing single-molecule molecular inversion probes (smMIPs). The smMIP protocol uses a hybridization-capture approach to selectively enrich and amplify both DNA strands of 92 regions in 32 genes in a single reaction. Unique molecular identifiers (UMIs) facilitate computational correction of sequencing errors to enable reliable detection of variants ≥0.5% variant allele frequency (VAF), with the additional advantage of relatively low reagent and sequencing costs of < $100 per sample. The smMIP assay was used to evaluate MRD status on pre-HSCT bone marrow samples from 98 AML pts who received an HSCT in first (n=83) or second (n=15) complete remission with or without count recovery. Median age at HSCT was 59 (range 20-75) years, 42% were female; 70% had de novo AML, 19% had an antecedent myeloid neoplasm and 11% had AML post cytotoxic therapy. European LeukemiaNet (ELN)-2022 risk groups at diagnosis were favorable in 11%, intermediate in 33%, adverse in 20% and unknown in 22%. All pts had received intensive induction chemotherapy. Twenty-nine percent received a myeloablative conditioning regimen (MAC), while 23% received reduced intensity conditioning (RIC) and 48% a non-myeloablative (NMA) conditioning regimen. Donors were matched related (18%), haploidentical (6%), or matched (55%) or mismatched (21%) unrelated. The median follow-up for pts alive was 34.8 months. Results Overall, we detected 190 variants in 71 (72%) of 98 pre-HSCT remission samples. The most commonly affected genes were DNMT3A (in 37% of pts), TET2 (21%), PPM1D (12%), IDH2 (10%) and TP53 (5%). Twenty-nine percent of pts had only variants affecting the clonal hematopoiesis-related genes DNMT3A, TET2 or ASXL1 (‘DTA‘), while 44% of patients had ≥1 variant involving a non-DTA gene. MRD-positive pts, defined as those with ≥1 non-DTA variant, had similar baseline and HSCT-related characteristics (includingage, sex, ELN risk group, de novo vs. secondary AML) compared to pts without non-DTA variants. Overall survival (OS) was significantly inferior in NGS MRD-positive pts compared to those with no non-DTA variant (Figure A, 5-year OS, 49% vs. 85%, P=.011). MRD-positive pts also had a non-significant higher cumulative incidence of relapse at 5 years (46% vs. 24%, P=.14), while non-relapse mortality was similar in both groups (P=.72). We next performed multivariable analyses, considering variables associated with OS at an univariable P<.10 (MRD status, patient sex, therapy-related AML, conditioning intensity), and using stepwise backward variable selection to identify factors significantly associated with OS (Figure B). In the final multivariable model, pre-HSCT MRD detection remained associated with inferior OS (hazard ratio 2.51; 95% confidence interval, 1.07 - 5.91; P=.035). Female sex associated with favorable OS, while myeloablative conditioning (MAC) showed a borderline significant association with superior OS. Of note, we did not detect an interaction between conditioning intensity and detection of MRD with regard to OS, i.e. the prognostic association of MRD detection was not different between pts receiving myeloablative or less-intensive conditioning. However, this analysis was limited by the small patient number. Conclusion Detection of MRD by targeted NGS using the smMIPs approach provides prognostic information in pts undergoing allogeneic HSCT, including those without established molecular markers such as NPM1mut. This method is applicable to a large proportion of AML pts and is cost-efficient for broad clinical use. S.M.K. and T.H., and M.J. and K.H.M. contributed equally to this abstract.

Subgroup Analyses of Progression-Free Survival from the Phase 3 Octans and Alcyone Studies in Transplant-Ineligible Patients with Newly Diagnosed Multiple Myeloma Treated with Bortezomib, Melphalan, and Prednisone with or without Daratumumab

Introduction:Daratumumab, a human IgGκ monoclonal antibody targeting CD38, has shown clinical efficacy in combination with standard-of-care regimens in patients with newly diagnosed multiple myeloma (NDMM). The addition of daratumumab to bortezomib, melphalan, and prednisone (D-VMP) significantly improved clinical outcomes vs bortezomib, melphalan, and prednisone (VMP) in phase 3 studies in Asian patients (OCTANS) and a global population (ALCYONE) with transplant-ineligible (TIE) NDMM. Here, we present subgroup analyses of progression-free survival (PFS) by measurable residual disease (MRD) and cytogenetic risk status from OCTANS and ALCYONE. Methods: Eligible patients from OCTANS (NCT03217812) and ALCYONE (NCT02195479) had a diagnosis of NDMM and were TIE due to age or comorbidities. Patients were randomized to receive up to nine 42-day cycles of VMP (bortezomib 1.3 mg/m 2 SC twice weekly in Cycle 1 and weekly in Cycles 2-9, and melphalan 9 mg/m 2 and prednisone 60 mg/m 2 orally on Days 1-4 of each cycle) or D-VMP (VMP + daratumumab 16 mg/kg IV weekly in Cycle 1, every 3 wk in Cycles 2-9, and every 4 wk thereafter until disease progression or unacceptable toxicity). MRD negativity (10 -5) was assessed by multi-parameter flow cytometry in OCTANS and next-generation sequencing in ALCYONE. Cytogenetic risk was assessed by FISH or karyotype testing. Results:A total of 220 Asian patients were randomized (D-VMP, n = 146; VMP, n = 74) in OCTANS, and 706 global patients were randomized (D-VMP, n = 350; VMP, n = 356) in ALCYONE. With a median follow-up of 41.2 mo (range, 0.0-59.9) in OCTANS, the median PFS was 38.7 mo with D-VMP and 19.2 mo with VMP (HR, 0.35; 95% CI, 0.23-0.52; P <0.0001). With a median follow-up of 40.1 mo (range, 0.0-52.1) in ALCYONE, the median PFS was 36.4 mo with D-VMP and 19.3 mo with VMP (HR, 0.42; 95% CI, 0.34-0.51; P <0.0001). The rates of overall and sustained MRD negativity were higher with D-VMP vs VMP. In OCTANS, the MRD-negativity rate was 40.4% with D-VMP vs 10.8% with VMP ( P <0.0001), and more patients in the D-VMP group had sustained MRD negativity lasting ≥12 mo (24.7% vs 1.4%; P <0.0001) and ≥18 mo (15.1% vs 1.4%; P = 0.0008). Similarly, in ALCYONE, the MRD-negativity rate was 28.3% with D-VMP vs 7.0% with VMP ( P <0.0001), with more patients in the D-VMP group having sustained MRD negativity lasting ≥12 mo (14.0% vs 2.8%; P <0.0001) and ≥18 mo (8.9% vs 1.7%: P <0.0001). In both studies, longer PFS was observed for patients who achieved MRD negativity vs those who did not within each treatment group; however, the PFS benefit observed for D-VMP vs VMP was maintained irrespective of MRD status ( Figure). In multivariate analyses, achievement of sustained MRD negativity lasting ≥12 mo was associated with longer PFS vs MRD negativity <12 mo in both OCTANS (HR, 0.23; 95% CI, 0.09-0.62; P = 0.004) and ALCYONE (HR, 0.13; 95% CI, 0.06-0.32; P <0.0001). No other factors showed a significant association with PFS in the multivariate analysis for OCTANS; other factors associated with longer PFS in ALCYONE included age <75 vs ≥75 y (HR, 0.38; 95% CI, 0.20-0.75; P = 0.005) and ISS disease stage I vs II (HR, 0.20; 95% CI, 0.05-0.86; P = 0.03). Data from OCTANS and ALCYONE were pooled for an analysis of PFS by cytogenetic risk subgroup (D-VMP, n = 496; VMP, n = 430). D-VMP prolonged median PFS vs VMP in patients with standard cytogenetic risk (not estimable vs 18.9 mo; HR, 0.33; 95% CI, 0.26-0.42) and high cytogenetic risk (25.6 vs 18.9 mo; HR, 0.54; 95% CI, 0.41-0.71), defined by the presence of t(4;14), t(14;16), del(17p), t(14;20), gain(1q21), and/or amp(1q21). Median PFS was also longer with D-VMP vs VMP for patients with gain and/or amp(1q21) (31.9 vs 18.9 mo; HR, 0.45; 95% CI, 0.32-0.63), 1 high-risk cytogenetic abnormality (HRCA; 24.4 vs 19.3 mo; HR, 0.62; 95% CI, 0.44-0.86), and ≥2 HRCA (28.2 vs 17.5 mo; HR, 0.36; 95% CI, 0.20-0.63). Conclusions:In this subgroup analysis of OCTANS and ALCYONE, the prolonged PFS observed with D-VMP vs VMP in the overall study populations was maintained irrespective of the achievement of MRD negativity or the presence of high cytogenetic risk. In addition, the rates of MRD negativity and sustained MRD negativity were higher with D-VMP vs VMP, and achievement of these deep responses translated into longer PFS, consistent with a prior pooled analysis of the MAIA and ALCYONE studies. These results further support the use of daratumumab in combination with VMP in both Asian and global patients with TIE NDMM.

Impact of Pre-Transplant Molecular and Cytogenetic Remission on Outcomes of Allogeneic Stem Cell Transplant in Patients with Myelodysplastic Syndrome

Background: Allogeneic stem cell transplant (allo-SCT) carries a high relapse rate (~35% within 2 years) in patients (pts) with myelodysplastic syndrome (MDS). Pre-transplant measurable residual disease (MRD) increases the risk of relapse and death in acute myeloid leukemia (Thol et al, Blood 2018). However, the impact of pre-transplant MRD on post-transplant outcomes is less clear in MDS. Prior studies have compared outcomes between myeloablative (MAC) and reduced intensity conditioning (RIC) in pts with pre-transplant MRD persistence based on either cytogenetic remission alone or ultra-deep genomic sequencing with a limited 10-gene panel, suggesting reduced risk of relapse in pts receiving MAC (Festuccia et al, Biol Blood Marrow Transplant 2016; Dillon et al, JCO PO 2021). However, pre-transplant MRD assessment using a commercial next-generation sequencing (NGS) panel in addition to cytogenetic testing to assess post-transplant outcomes has not been evaluated in MDS. Methods: We conducted a multicenter retrospective review of MDS pts who underwent allo-SCT from 2015-2022. Pts with FISH/cytogenetic (FC) and/or molecular abnormalities at diagnosis and MRD assessment by commercial myeloid-panel NGS (with a variant-allele frequency detection limit up to 5%) and FC performed on peripheral blood (PB) or bone marrow (BM) aspirate within 3 months prior to transplant were included for analysis. The Kaplan-Meier method and log-rank tests were used to estimate overall survival (OS). Gray's test/cumulative incidence functions were used to estimate relapse-free survival (RFS) with non-relapse mortality (NRM) as competing risk. Results: Table 1 includes baseline pt characteristics. Of 81 pts, 69 pts (85.2%) had residual FC and/or molecular abnormalities (MRD+) at pre-transplant PB/BM assessment. Twelve (14.8%) pts were in both FC and molecular remission (MRD-) prior to transplant. With a median follow-up of 13.9 months [IQR 6.8 - 38.9], 43 (53%) died and 24 (30%) pts experienced a relapse. Twenty-three of 69 (33%) MRD+ pts had relapsed disease with a 38% cumulative incidence of relapse (CIR) at 2 years. In contrast, only 1/12 (8.3%) MRD- pts experienced a relapse after 7 years, with chromosomal loss of TP53 not present at initial diagnosis. CIR at 2 years was 33% and 41% (p=0.207) for MRD+ pts who received MAC vs RIC, respectively with NRM of 34.5% associated with MAC vs 28.2% for RIC (p=0.61). TP53 mutations were most frequently associated with relapse in 8/24 (33%) pts with a median OS of 9.8 months [8.2 - NR]. Besides the previously defined 10-gene panel (Dillon et al, JCO PO 2021), relapses were also driven by SRSF2, U2AF1, KRAS, SETBP1 and NF1 mutations present in the original clone. Six pts had DNMT3A, TET2 and/or ASXL1 (DTA) mutations only on pre-transplant NGS, with 2/6 pts relapsing without the re-emergence of DTA mutations. Median OS was not reached for MRD- pts and was 14.1 months [11.35-NR] for MRD+ pts, p = 0.061 [Fig.1]. OS probability at 2 years was 35% for MRD+ pts vs 75% for MRD- pts. Type of conditioning regimen, RIC vs MAC, did not impact OS (p= 0.6). An equal number of deaths, 35% each, were attributable to GvHD and relapse, respectively. Thirteen (30%) pts died from other causes, primarily infections and bleeding complications. NRM was 25% and 36% for MRD- and MRD+ cohorts, respectively. Pts received a median of 6 cycles [range, 2-36] of hypomethylating agent (HMA) +/- venetoclax prior to transplant with no association between the number of cycles and MRD status (p=0.80). The incidence of grade 3-4 acute GvHD and chronic GvHD requiring systemic therapy did not significantly differ, at 25% and 18.8% (p= 0.696) and 33.3% and 31.8% (p= 1.00) in MRD+ and MRD- pts, respectively. Conclusions: MRD assessment using commercially available NGS panels and cytogenetic testing that are routinely performed in MDS pts in real-world practice can predict risk of relapse. Pre-transplant MRD is associated with worse OS irrespective of the intensity of conditioning regimen. Although limited in statistical power due to a small sample size of MRD- pts in our cohort, further studies with a larger cohort are underway to better clarify the role of MRD on transplant outcomes in MDS. Our data also highlights that only a small minority of MDS pts (<15%) achieve complete molecular and cytogenetic remission at the time of transplant; strategies to eliminate the pre-transplant MDS clone are urgently needed.

Clinical Characteristics, Genetic Profile and Prognosis of Adult Acute Myeloid Leukemia with NUP98 Rearrangement

Introduction: Nucleoporin 98 ( NUP98) rearrangement has been proposed in 2022 as one type of acute myeloid leukemia (AML) with defining genetic abnormalities. It occurred more often in pediatric leukemia with poor outcome. However, in adult AML with NUP98 rearrangement, patients may show different clinical characteristics, genetic profile and outcome, as we reported here. Method: We retrospectively collected and analyzed the data of adult AML patients with NUP98 rearrangement who were diagnosed at Shanghai Institute of Hematology from May 2019 to December 2022, including clinical characteristics, laboratory examination, genetic abnormalities, treatment strategies and outcome. All patients underwent next generation sequencing and RNA sequencing. Result: A total of 21 AML patients with NUP98 rearrangement were included in this study, counting for 2.3% of all AML patients (930 cases). The median age was 40 (19-64) years old. The median white blood cell and platelet count was 31.1 (1.5-313.6) and 48 (15-140) ×10 9/L, respectively. Interestingly, 11 (52.4%) patients suffered from severe or fatal hemorrhage irrelative with platelet count or coagulative function, including 4 cerebral bleeding (3 died), 1 urgent uterine bleeding, 1 gastro-intestinal bleeding, 1 retina bleeding and 4 massive bleeding of subcutaneous soft tissue or mucous membranes. The FAB types involved M2, M4 and M5. Eight patients carried normal karyotype, 6 were found with t(7;11)(p15;p15), all of whom had NUP98::HOXA9 fusion gene, 2 with +8 and 1 complex karyotype. According to ELN 2022 risk classification, 14 (66.7%) were at intermediate risk and 6 (28.6%) at adverse risk, 1 unclassified. Five fusion partners with NUP98 were detected: NUP98::NSD1 (11 cases), NUP98::HOXA9 (7 cases), NUP98::HOXA11, NUP98::HMGB3 and NUP98::TNRC18 (each with 1 case). Of which NUP98::TNRC18 was first reported by our center (see Cheng WY, et al. Proc Natl Acad Sci U S A. 2022;119(49):e2211429119). NUP98 rearrangement also co-existed with several mutations. FLT3-ITD (12 cases, of which 10 were co-existed with NUP98::NSD1) and WT1 (7 cases) were most frequently occurred. Patients with relapse/refractory disease had more additional mutations than de novo status (Figure 1). Nineteen patients were treated with standard dose of “7+3” induction therapy, and 2 with hypomethylating agents (HMA) plus venetoclax (VEN). Complete remission (CR) was achieved by 8 (38.1%) patients after first induction, 2 (9.5%) early deaths were both due to cerebral hemorrhage. Salvage induction varied from intensive chemotherapy (IC, including “7+3” and CLAG±M) to low-intensity therapy (LIT, including priming chemotherapy±HMA and HMA+VEN). FLT3 inhibitors (FLT3i) were added to 5 patients carrying FLT3-ITD, and they all achieved CR. A total of 15 (71.4%) patients achieved CR after 1-2 courses of induction (8 mainly benefited from IC, 7 mainly benefited from LIT±FLT3i), 1 survived from allogeneic hematopoietic stem cell transplantation (allo-HSCT) without reaching remission before, and 3 died from refractory disease within 6 months. Three patients relapsed after CR, 2 died without allo-HSCT, and the other one survived after CR2 and sequential allo-HSCT. A total of 14 patients underwent allo-HSCT after CR, 7 were measurable residual disease (MRD) negative and 7 were positive by flow cytometry before HSCT, none of them relapsed till the last follow-up. With a median follow-up time of 19.2 months, the median overall survival (OS) and event-free survival (EFS) were not reached, estimated 2-year OS and EFS rate were 66.7% and 57.1%, respectively. For patients achieving CR or not, the median OS were not reached vs 3.2 months (95% CI 0-8.361, P<0.001, Figure 2). Ten patients were diagnosed with NUP98::NSD1 co-occurring with FLT3-ITD (once considered as unfavorable prognosis), ending up with a CR rate of 70%, and a 2-year OS and EFS rate of 80% and 60%, respectively, making no significant difference compared to others ( P=0.236 and 0.725, respectively). Conclusion: Adult AML with NUP98 rearrangement may combine with a set of partner fusion genes and mutations, with NUP98::NSD1 and FLT3-ITD as the most common combination. Both IC an LIT can induce CR, and FLT3i will benefit those with FLT3 mutations, also prevention of fatal bleeding should be paid attention to. After achieving CR with whatever method and whatever MRD status, allo-HSCT is the key to long-term survival.

The Prognostic Impact of Measurable Residual Disease Dynamics in Mantle Cell Lymphoma

Introduction Measurable residual disease (MRD) technologies have greatly enhanced our ability to guide treatment duration and predict outcome in various hematologic malignancies. However, drawing definitive conclusions on the benefits of achieving MRD-negative status in patients with mantle cell lymphoma (MCL) has been challenging due to the limited availability of large-scale MRD detection series. To address this, our study aimed to determine the optimal timing for MRD detection and explore the prognostic value of MRD dynamics in MCL. Methods In present study, we included 102 patients diagnosed with advanced MCL demonstrating clonal B cell involvement in bone marrow (BM) detectable by multiparametric flow cytometry (MFC). 60/102 (58.8%) patients received high dose cytarabine-based intensive immunochemotherapy. BM aspirates were collected and MRD assessment was conducted at specific time points, including the initiation of cycle 3, cycle 5, at the end of induction, and every 6 months during maintenance therapy. Results 77/102 (75.4%) patients reached MRD negativity throughout induction treatment. Of those with MRD − vs MRD + status , 23.4% vs 68.0% were aged >65 years respectively, which was likely a consequence of the greater MRD − rates observed in patients who received intensive immunochemotherapy and auto-transplantation. Besides, elevated lactate dehydrogenase (LDH) level, high-risk MIPI, blastoid/pleomorphic pathology type, and non-cytarabine containing regimen were associated with a lower rate of MRD negativity. Follow-up data revealed that MRD-negative patients had significantly better survival (P<0.001). In subgroup analyses, MRD negativity was prognostic in almost all subgroups. MRD detection serves as a valuable complement to the traditional response evaluation system, particularly benefiting patients who achieve partial remission (PR). This indicated the importance of assessing MRD during induction therapy for PR patients. However, for patients who achieve complete remission (CR), the presence or absence of MRD has minimal impact on prognosis (P=0.921 for progression-free survival (PFS), and P=0.399 for overall survival (OS). Then we evaluated the optimum timing of MRD detection and impact of rapidity of MRD negativity. 31 of the 77 patients (40.3%) had a rapid reduction of tumor burden and achieved MRD negativity after two cycles of treatment. 35 patients (45.5%) were MRD negative after four cycles of treatment. In 14.2% of the patients, MRD turned negative only at the evaluation after six cycles of induction therapy or during maintance duration. Comparing MRD status at different time points, the MRD status after four cycles of therapy was the strongest predictor of survival prognosis (HR=5.37, C-index=0.673). However, the speed of reaching MRD negativity was not significantly correlated with survival prognosis. Patients with high-risk features, such as high-risk MIPI, elevated LDH levels and complex karyotype, tend to achieve MRD negativity at a faster speed, often within two treatment cycles. However, faster rate of achieving MRD negativity did not confer any prognostic benefit to these patients. The overall MRD negativity rate was relatively low, and the prognosis for these patients was worse compared to other patients. In the high dose cytarabine-based intensive immunochemotherapy group, patients who achieved a rapid MRD negativity within two cycles of treatment showed a slightly longer PFS compared to those who achieved MRD negativity after 4-6 cycles (P=0.017). However, there was no significant difference in OS between the two groups. Conclusions In summary,the optimal timing for MRD testing is after four treatment cycles, as this time point demonstrated the best predictive ability for survival prognosis. However, the speed of achieving MRD negativity was not found to be linked with survival prognosis. Although certain high-risk features may lead to faster achievement of MRD negativity, this rapidity did not confer any additional prognostic benefit to these patients. Importantly, our results suggest that the value of MRD negativity as a prognostic marker may be limited in patients who have achieved complete remission and those with blastoid/pleomorphic morphologies. These findings underscore the need for tailored approaches to MRD testing and interpretation in MCL, in alignment with individual patient characteristics and treatment responses.

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 >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.

Relative Prognostic Value of Flow Cytometric Measurable Residual Disease before Allogeneic Hematopoietic Cell Transplantation for Adults with MDS/AML or AML

Background: Measurable residual disease (MRD), assessed by multiparameter flow cytometry (MFC) before allogeneic hematopoietic cell transplantation (HCT), is strongly and independently associated with poor post-HCT outcomes in adults with acute myeloid leukemia (AML). On the other hand, the relative prognostic value of MFC-based MRD testing is unknown in patients with myelodysplastic neoplasm (MDS)/AML, a disease entity newly defined by the 2022 International Consensus Classification (ICC) that encompasses cases of MDS with 10-19% blasts and recognizes the diagnostic continuum between MDS and AML. Methods: To assess the relationship between pre-HCT, disease type, and post-HCT outcomes, we retrospectively analyzed 1,262 adults ≥18 years with MDS/AML (n=150) or AML (n=1,112), based on the ICC 2022 criteria, who received a first allograft while in first or second morphologic remission at a single institution between 4/2006 and 3/2023. Results: The MDS/AML and AML cohorts differed significantly regarding patient and disease-specific characteristics, including age at HCT (60 vs. 56 years in MDS/AML and AML patients, respectively, P<0.001), HCT-CI score ( P<0.001), adverse cytogenetic risk according to ELN 2022 criteria (39% vs. 26%, P<0.001), intensive therapy prior to allogeneic HCT (69% vs. 97%, P<0.001), time from last remission (76 vs. 98 days, P<0.001), first remission status (97% vs. 77%, P<0.001), pre-HCT MRD by MFC (35% vs. 19%, P<0.001), and peripheral blood stem cells as graft source (89% vs. 80%, P=0.015). There were no differences in donor source or conditioning intensity. With a median follow-up of 5.11 years (interquartile range [IQR]: 2.38-9.66) in survivors, there were 384 relapses, 590 deaths, and 258 non-relapse mortality (NRM) events contributing to the estimates for relapse, NRM, relapse-free survival (RFS), and overall survival (OS). At three years, NRM (21% [14-28%] for MDS/AML vs. 16% [14-19%] for AML, P=0.19), relapse (29% [22-36%] vs. 29% [27-32%], P=0.94), RFS (50% [42-59%] vs. 54% [51-58%], P=0.25), and OS (52% [44-61%] vs. 60% [57-63%], P=0.09) were similar between the two groups. After multivariable adjustment, relapse rates for patients with MDS/AML vs. those with AML were similar (hazard ratio [HR]=0.77 [0.50-1.17], P=0.2), as were NRM (HR=1.41 [0.91-2.18), P=0.12), RFS (HR=0.99 [0.73-1.35], P>0.9) and OS (HR=1.17 [0.85-1.61], P=0.3). Importantly, a significant interaction was found between pre-HCT MRD status and disease type (MDS/AML vs. AML) for relapse ( P=0.009), RFS ( P=0.013), and OS ( P=0.048). The interaction models indicated that the HRs for the association between pre-HCT MRD and post-HCT outcomes were lower in patients with MDS/AML (for relapse: HR=1.73 [0.96-3.11] in MDS/AML vs. HR=3.56 [2.90-4.38], in AML; for RFS: HR=1.60 [1.03-2.48] vs. HR=2.67 [2.25-3.16]; for OS: HR=1.53 [0.97-2.39] vs. HR=2.34 [1.96-2.78]). Pre-HCT MRD was associated with a higher risk of relapse in both MDS/AML and AML patients but to a lesser extent in the MDS/AML patients. In these patients, relapse at three years was 37% [24-51%] for those with pre-HCT MRD vs. 24% [16-33%] for those without ( P=0.068), translating into lower RFS (39% [28-56%] vs. 56% [47-67%], P=0.038) and OS (41% [29-58%] vs. 58% [48-70%], P=0.066) in MDS/AML patients with pre-HCT MRD. For comparison, in patients with AML, relapse at three years was 22% [20-25%] for those without MRD vs. 56% [50-62%] for those with ( P<0.001), translating into lower RFS (27% [22-31%] vs. 61% [58-64%], P<0.001) and OS (35% [29-42%] vs. 65% [62-68%], P<0.001) in those with pre-HCT MRD. In line with these findings, C-statistics showed that pre-HCT MRD was not as predictive in MDS/AML patients in comparison to AML patients (for relapse: 0.57 in MDS/AML patients vs. 0.62 in AML patients; for RFS: 0.57 vs. 0.59; for OS: 0.56 vs. 0.58). Conclusion: Our data suggest that, overall, patients with MDS/AML or AML in first or second morphologic remission have similar outcomes following allogeneic HCT. However, MFC-based pre-HCT MRD testing is prognostically substantially less informative for MDS/AML than AML patients, possibly because of increased rates of misclassification. These findings support the rationale to examine the prognostic value of molecular MRD testing in patients with MDS/AML. Figure. Cumulative incidence of relapse stratified (A) by disease type at diagnosis and (B) by disease type at diagnosis and pre-HCT MRD.

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 >5% in CR/CRi samples may indicate clonal hematopoiesis, we excluded all variants with VAF >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.

Quantum-First Trial: FMS-like Tyrosine Kinase 3-Internal Tandem Duplication ( FLT3-ITD)-Specific Measurable Residual Disease (MRD) Clearance Assessed through Induction (IND) and Consolidation (CONS) Is Associated with Improved Overall Survival (OS) in Newly Diagnosed (nd) FLT3-ITD+ AML Patients (pts)

Background Detection of MRD by flow cytometry or gene fusion transcript quantitation increasingly is used to guide treatment decisions in AML. Molecular monitoring of recurrent gene mutations for MRD detection is an alternative strategy but, other than for nucleophosmin 1 ( NPM1) gene quantitation, remains controversial. FLT3-ITD is among the most common recurrent mutations in AML and confers a worse prognosis vs FLT3-wild-type and FLT3-TKD+ AML. Routine use of FLT3-ITD detection in remission as a predictor of relapse risk or OS has been limited by the low sensitivity of both conventional PCR-based detection methods and broad NGS platforms in clinical practice settings. More recently, FLT3-ITD-specific PCR-NGS assays such as getITD (PMID: 31089248) show greater sensitivity and ease of interpretation that point to eventual routine clinical application. However, the clinical value of these measurements has not been evaluated prospectively in large scale randomized controlled trials of FLT3 inhibitors. The phase 3 QuANTUM-First study (NCT02668653) evaluated the novel, potent, and highly selective type II FLT3 inhibitor quizartinib (Quiz) in nd FLT3-ITD+ AML pts and demonstrated that Quiz added to intensive IND and CONS, ± transplant, followed by single-agent continuation (CONT) therapy (Tx) resulted in a significant improvement in OS (PMID: 37116523). We analyzed if FLT3-ITD-specific MRD in QuANTUM-First pts impacted the clinical outcome or the benefits provided by Quiz in nd FLT3-ITD+ AML pts. Methods Genomic DNA, isolated from bone marrow aspirates or peripheral blood from pts after achievement of remission after 1 or 2 courses of IND and at end of CONS (prior to transplant or CONT cycle 1 day 1 [C1D1] for transplant pts and prior to CONT C1D1 for non-transplant pts), was analyzed with a FLT3-ITD PCR-NGS assay specifically developed for this trial (PMID: 31722002). ITD mutations detected after IND were cross-validated against the ITD detected at enrollment for each patient. Using a custom bioinformatics program, ITD mutations were identified, and variant allele frequencies (VAFs) were calculated with a sensitivity of 10 −5. MRD was classified as undetectable (using the 0 cutoff) or detectable above or below a 10 −4 predefined cutoff (based on lower limit of quantification for the assay). Comparisons of complete response (CR), composite complete response (CRc=CR+CRi), and the rate of pts achieving CRc during IND with no MRD between arms were made using a stratified Cochran-Mantel-Haenszel test. Comparison of FLT3-ITD VAF during IND and during CONS between arms was made using Wilcoxon rank sum test. All P-values were not adjusted for multiplicity. Results In QuANTUM-First, 539 nd FLT3-ITD+ AML pts were randomized to Quiz (n=268) or placebo (PBO; n=271). Of the 539 randomized pts, 368 (68.3%) achieved CRc after 1 or 2 courses of IND, and MRD analysis was performed on 321 (87.2%) of these pts (162 pts in Quiz and 159 pts in PBO) using samples collected at the time of response assessment during IND, before further Tx. MRD was also assessed in 337 pts (172 pts in Quiz and 165 pts in PBO) by end of up to 4 cycles of CONS prior to CONT/maintenance Tx. Of these pts, 166 additionally received transplant (87 in Quiz, 79 in PBO). The % of pts in CRc at end of IND with FLT3-ITD MRD of <10 −4 was similar between study arms (25.4% Quiz vs 21.8% PBO, nominal P = 0.3430), however, a greater % of pts in CRc had undetectable MRD with Quiz than PBO (12.3% vs 7.0%, nominal P = 0.0403). Among pts with CRc at end of IND, the median best FLT3-ITD VAF by end of CONS was lower (0% versus 0.0017%; nominal P = 0.0006) with Quiz vs PBO (Fig 1) and, using the 0 cutoff at end of IND, a longer OS was observed with Quiz vs PBO, regardless of MRD status, with a greater effect with Quiz (HR, 0.789 in MRD− pts; HR, 0.749 in MRD+ pts; Fig 2). In MRD+ pts, the median OS was not reached with Quiz and 35.4 months with PBO (Fig 2). Performing this analysis with an MRD cutoff of 10 ‒4 yielded similar findings (HR, 0.696 in MRD− pts; HR, 0.800 in MRD+ pts). Additional data about MRD impact on pts ± transplant in this trial will be presented. Conclusions These findings demonstrate the potential prognostic utility of FLT3-ITD-specific MRD measurements in the clinical management of pts with FLT3-ITD+ AML. Our data suggest that long-term OS benefits conferred by Quiz in part derive from a deep and sustained reduction of the FLT3-ITD+ leukemia burden.

Measurable Residual Disease As Assessed By Flow Cytometry As Predictor of Survival in Pediatric AML Patients

Introduction Pediatric acute myeloid leukemia (pedAML) is a heterogeneous group of hematological malignancies classified according to morphology, immunophenotyping, and genomics. The optimal adjustment of therapy based on level of response is not well defined. Aim: Herein, we present the results of a retrospective study aiming to analyze the prognostic value of measurable residual disease (MRD) as determined by flow cytometry (FC-MRD) in pediatric AML. Patients and Methods All pediatric and adolescent patients (aged 0-18 years old) with AML treated in our unit between 1/2013-6/2023 were included in this study. French American British (FAB) morphological classification, immune-phenotype analysis, and molecular characterization were performed on diagnosis, and all patients were treated according to AML-BFM protocols. Final risk classification was based on evaluation of response and on genetic abnormalities at diagnosis. MRD was assessed by FC-MRD after Induction 1 and 2, and, either after course 5 or before hematopoietic stem cell transplantation (HSCT). Complete Remission (CR) was defined as regenerative or normocellular bone marrow with <5% blasts; in peripheral blood ≥1.0x10 9/L neutrophil granulocytes and ≥80x10 9/L thrombocytes or Remission with partial regeneration ( CRp: regenerative or normocellular bone marrow with <5% blasts; in the blood: ≥1.0x10 9/L leukocytes, ≥0.5x10 9/L, neutrophil granulocytes and ≥50x10 9/L, self-sustained platelets), lasting at least 4weeks; no extramedullary disease. Overall survival (OS) was defined as the time interval from the treatment initiation date to the date of death due to any cause. Progressive free survival (PFS) was defined as the time interval from the response date to the date of disease relapse or death due to any cause. The probabilities of OS and PFS were estimated with the Kaplan-Meier method. Results Overall, there were 52 patients (median age at diagnosis:7 years, 37males/15 females) diagnosed with AML, of whom: 40 patients with de novo AML, 5 patients with therapy- or myelodysplasia-related AML and 7 patients with mixed-lineage leukemia. Cytogenetics were considered favorable for 16 (31.0%), intermediate for 4 (7.6%), and adverse for 32 (61.4%) patients. Standard-risk patients (n=16) received only chemotherapy, whereas all high-risk patients, and intermediate-risk patients with available matched donors, underwent HSCT should they have reached remission. Forty-four patients (84.6%) achieved complete response (CR). Among these patients, 43 patients (97.7%) achieved CR after 1 course of induction, and 1 patient (2.3%) required at least 2 courses. Twenty-four patients (46.1%) underwent HSCT during either their first (20/24) or second (4/24) CR. Overall, 12 patients (23.07%) died, 4 patients due to resistant disease, 3 patients due to relapse, 2 patients due to serious complications upon diagnosis, 1 patient due to infection and 2 patients due to transplant-related complications. With a median follow-up time of 3.7 years (range 0.1-11.1years), the five-year OS and PFS of the entire cohort was 74.0% and 70.0%, respectively. The level of FC-MRD was a significant prognostic factor for OS and PFS. More specifically, achievement of FC-MRD < 0.1% at all time points was associated with a significant improvement in PFS and OS. (figure 1). FC-MRD ≥ 0.1% after course 5 or before HSCT was the only independent adverse prognostic factor that was statistically significant for both progression-free (P=0.001) and overall survival (P<0.001) (figure1). Conclusions We investigated the association between FC-MRD and survival in Greek pediatric patients with AML. In our cohort, achieving an MRD status <0.1% according to FC is associated with significant improvement in the outcome of pediatric patients with AML.

Updated Results from a Phase II Study of Hyper-CVAD, with or without Inotuzumab Ozogamicin, and Sequential Blinatumomab in Patients with Newly Diagnosed B-Cell Acute Lymphoblastic Leukemia

Background Blinatumomab improves overall survival (OS) compared with chemotherapy in patients (pts) with relapsed/refractory B-cell acute lymphoblastic leukemia (ALL) and is also FDA-approved for eradication of persistent or recurrent measurable residual disease (MRD). Blinatumomab also improves OS when added to standard chemotherapy, irrespective of MRD status, in newly diagnosed Philadelphia chromosome (Ph)-negative B-cell ALL. Inotuzumab ozogamicin (INO) improves OS in the relapsed/refractory setting, and we hypothesized that the addition of INO to hyper-CVAD plus blinatumomab would lead to deeper and more durable responses, reduce relapses, and improve survival. Methods In this phase II study, pts age 14-59 with newly diagnosed Ph-negative B-cell ALL, including pts who had received no more than 1 prior cycle of chemotherapy, were eligible. Pts had to have a performance status of ≤3, total bilirubin ≤2 mg/dl, creatinine ≤2 mg/dl, and no significant CNS pathology (except for CNS leukemia). Pts received hyper-CVAD alternating with high-dose methotrexate (MTX) and cytarabine (Ara-C) for up to 4 cycles, followed by 4 cycles of blinatumomab at standard doses. Pts with CD20+ disease (≥1% cells) received 8 doses of ofatumumab (2000 mg) or rituximab (375 mg/m2). Eight doses of prophylactic IT chemotherapy were given. Maintenance was with alternating blocks of POMP (given in maintenance cycles 1-3, 5-7, 9-11, and 13-15) and blinatumomab (given in maintenance cycles 4, 8, and 12). Those with high-risk disease features started blinatumomab after 2 cycles of hyper-CVAD. Beginning with pt #39, INO at a dose of 0.3 mg/m2 on day 1 and 8 was added to the 2 cycles of MTX/Ara-C (which was also dose reduced to 500 mg/m2 of MTX and 1 g/m2 of Ara-C with this amendment) and to 2 cycles of blinatumomab consolidation (4 total cycles with INO). Results As of June 2023, 75 pts have been treated (38 without INO and 37 with INO). Pt characteristics are shown in Table 1. The median age across both cohorts was 33 (range, 18-59). 36 pts (48%) had ≥1 high-risk pretreatment characteristic at enrollment (e.g. poor-risk cytogenetics, CRLF2 overexpression by flow and/or TP53 mutation). Sixteen pts were in complete remission (CR) at enrollment after 1-2 cycles of off-protocol therapy, 10 of whom were MRD-negative by 6-color flow cytometry. All 59 pts (100%) with active disease upon study entry achieved CR, with 50 pts (84%) achieving CR after the first cycle. MRD negativity by flow (sensitivity 10 -4) was achieved in 60 of 65 evaluable pts (92%), with 43 pts (66%) achieving flow MRD negativity after the first cycle. Two of the 5 patients who did not achieve flow MRD negativity had NUP214::ABL1 fusion, 1 had KMT2A rearrangement, and 2 are still early in treatment and have not yet received blinatumomab. Overall, 25 of 36 tested pts (69%) achieved next-generation sequencing-based MRD negativity at a sensitivity of 10 -6. The median duration of follow-up is 26 months (range, 1-77 months). Overall, 8 pts (11%) relapsed in the absence of SCT, 23 pts (31%) underwent stem cell transplantation (SCT) in first remission (2 of whom relapsed post-SCT), 3 pts (4%) died in CR, and 41 pts (55%) remain in continuous remission without SCT. Among the 10 relapses, 3 were in the CNS, 2 of which were CNS-only. All but one relapse occurred in pts with ≥1 poor-risk feature(s). Across both cohorts, the estimated 3-year OS was 88% and the 3-year relapse-free survival (RFS) was 79% . The 3-year OS rate for pts without a high-risk baseline feature was 93% vs 83% in pts with ≥1 high-risk feature. In a landmark analysis, there was no difference in outcomes between pts who underwent SCT in first remission versus those who did not (3-year OS: 90% versus 87%). With a median follow-up of 18 months in the INO group, 3 pts (8%) have relapsed, 2 with CNS-only relapses, and none have died. The 18-month RFS in the cohorts with and without INO were 92% vs 76% (p=0.18), and the OS was 100% vs 84% (p=0.04) ( Figure 1). One pt discontinued blinatumomab due to a related adverse event (grade 2 encephalopathy and dysphasia). No pts discontinued INO due to toxicity, and no cases of veno-occlusive disease have been observed.

Deep Sequencing Is a Widely Applicable Tool for Relapse Prediction in Acute Myeloid Leukemia with Mutated NPM1

Analysis of measurable residual disease (MRD) is a powerful tool for assessment of treatment response in acute myeloid leukemia (AML). In patients with mutation in NPM1, reverse transcription quantitative polymerase chain reaction (RT-qPCR) is recommended by European Leukemia Net for refinement of risk stratification and monitoring after treatment. However, since RT-qPCR is mutation-specific and requires stringent quality control, many clinical laboratories restrict NPM1 monitoring to the type A mutation (c.860_863dupTCTG) although >50 mutations have been reported in exon 12. Deep sequencing is an alternative method, performed on DNA, that covers all NPM1 exon 12variants in the same assay. Guidelines for its clinical use are however lacking. We here performed a retrospective analysis in a population-based cohort of AML patients to evaluate if deep sequencing MRD analysis of NPM1 during chemotherapy provides prognostic information. Adult patients with AML with mutated NPM1 treated with curative intent in our region during 2006-2016 who achieved complete remission (CR) or CR with incomplete count recovery (CRi) were eligible for the study. This time period was chosen to avoid inclusion of patients treated based on molecular MRD status. Through review of the national AML registry, clinical charts, and screening of diagnostic samples, 99 patients with mutated NPM1 were identified. Of these, 97 patients (60 women and 37 men, median age 64 years, range 19-82) had bone marrow slides for isolation of DNA from at least one time point during treatment. DNA from 257 bone marrow aspirate slides were assessed for MRD using deep sequencing of NPM1. Based on previous comparison with RT-qPCR (Pettersson et al, Int J Lab Hematol 2021;43:664-674), variant allele frequency (VAF) of ≥0.05% was chosen as cut-off to define deep sequencing MRD positivity (MRD pos). For subgroup analyses, patients were divided into groups of treatment intensity; high-dose (cytarabine- and daunorubicin-based, n=67) or low-dose (cytarabine- and daunorubicin-, or azacytidine-based, n=30) treatment regimens. Thirty-one patients underwent allogeneic stem cell transplantation (alloSCT). We first evaluated if deep sequencing MRD status during consolidation (n=70, analyzed after 2 or 3 cycles) had an impact on prognosis. Both 3-year relapse-free survival (RFS) (26.7±11.4% vs 71.6±6.2%, p=<0.001, Figure) and overall survival (OS) (33.3±12.2% vs 72.7±6%, p=0.004) were lower for patients that were MRD pos at any time point during consolidation than for MRD neg patients. Among MRD pos patients, 12/15 (80%) relapsed and 13/15 (87%) died, compared to 19/55 (35%) and 23/55 (42%) MRD neg patients. In univariate analyses, also age and treatment intensity, but not alloSCT or DNMT3A mutation status, predicted RFS and OS. FLT3-ITD predicted OS but not RFS, and there was no effect of FLT3-ITD allelic ratio. In Cox regression multivariate analysis including MRD, age, FLT3-ITD and treatment intensity, MRD pos was the only significant predictor of RFS (Hazard ratio (HR): 2.54, p=0.019). In the multivariate analysis, FLT3-ITD (HR: 2.43, p=0.014) and treatment intensity (HR: 0.43, p=0.035) were significant for OS (MRD pos HR: 1.75, p=0.13). When dividing the cohort based on treatment intensity, the effect of MRD status was most obvious in patients treated with low-dose regimens. When deep sequencing MRD analysis was performed post first cycle (n=96), it had no statistically significant effect on either RFS or OS. At the end of treatment (n=51), deep sequencing MRD status had a strong prognostic value with 3-year RFS and OS for MRD pos patients 30±14.5% and 40±15.5%, compared to 73.2±6.9% and 78±6.5% for MRD neg patients ( p=0.003 and p=0.006, respectively). In summary, this population-based study shows that MRD status by deep sequencing of NPM1 is predictive of both RFS and OS when assessed during or after consolidation. The study confirms the threshold of deep sequencing MRD pos of VAF 0.05% previously obtained by comparison with RT-qPCR. Since deep sequencing can be used for all NPM1 mutations, it is widely applicable and extends the use of molecular MRD analysis and risk refinement to patients with rare mutations in NPM1.

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.

Clinical Significance of Measurable Residual Disease (MRD) in Relapsed/Refractory Multiple Myeloma (RRMM) Patients (Pts) Treated with Chimeric Antigen Receptor (CAR) T Cells and T-Cell Engagers (TCE)

Clinical Significance of Measurable Residual Disease (MRD) in Relapsed/Refractory Multiple Myeloma (RRMM) Patients (Pts) Treated with Chimeric Antigen Receptor (CAR) T Cells and T-Cell Engagers (TCE)

Trial in Progress: A Phase 1b Single-Arm, Open-Label Study of Emavusertib (CA-4948) in Combination with Azacitidine and Venetoclax in Acute Myeloid Leukemia Patients in Complete Response with Measurable Residual Disease

Background Emavusertib is a novel potent oral inhibitor of interleukin-1 receptor-associated kinase 4 (IRAK4) with additional inhibitory activity against FMS-like tyrosine kinase 3 (FLT3) and CDC-like kinases (CLK1/2/4). Inhibition of these onco-proteins may induce remission thereby addressing a critical unmet need for novel therapies in acute myeloid leukemia (AML). Clinical studies with emavusertib monotherapy have demonstrated a significant reduction in AML blasts with clinical and molecular responses, including patients with relapsed or refractory AML, previously treated with an HMA and/or FLT3 inhibitors (Metzeler 2022). Azacitidine + venetoclax (aza+ven) has been approved in newly diagnosed, unfit patients with AML. In the VIALE-A study, composite complete response (CRc) (CR, CRh, or CRi) in the absence of measurable residual disease (MRD) of <1 residual blast/1000 leukocytes (MRD negative [MRD−]) resulted in longer duration of response (DOR), event-free survival, and overall survival (OS), and better HSCT outcome compared with patients who achieved CRc but were MRD+ (Pratz, 2022). In pre-clinical studies, emavusertib in combination with aza+ven demonstrated synergistic antileukemic effects in AML cell lines, including azacitidine- or venetoclax-resistant cell lines. Adding emavusertib to aza+ven in MRD+ patients at the time of CR may convert MRD status without adding significant toxicity and confirm that emavusertib can be safely added to aza+ven as a potential new regimen in front-line therapy. Study Design: This is a single-arm, open-label Phase 1b trial evaluating safety and tolerability, PK, and conversion of MRD status with emavusertib as an add-on agent to aza+ven in AML patients who achieved CR or CRh with MRD+ based on local testing (EU CT Number 2023-505828-58-00). The primary objective of the study is to determine a safe and tolerable dosing schedule for the triple combination. Secondary objectives include MRD conversion rate, DOR, OS, and pharmacokinetics. The study will enroll approximately 24 patients at 5 to 10 sites globally. Patients will have received azacitidine and venetoclax as first line therapy and achieved CR or CRh after 1-6 cycles of aza/ven. If MRD status remains positive, emavusertib will be added to the existing well tolerated aza+ven regimen. The starting emavusertib dose is 200 mg BID for 7 days per cycle of 28 days. If well tolerated, duration of emavusertib treatment will be extended to 14 and 21, respectively; no intra-patient change of emavusertib dosing duration is planned. The patients will continue triple treatment (emavusertib+aza+ven) until consent withdrawal, disease progression, intolerable toxicity, or not achieving MRD- within 6 cycles of triple treatment. In this Phase 1b trial, MRD can be evaluated by local testing of bone marrow. Key exclusion criteria include residual toxicities and significant comorbidities.

Outcome of Allogeneic Stem Cell Transplantation in FLT3-TKD-Mutated AML - a Study on Behalf of the Acute Leukemia Working Party of the EBMT

Introduction The overall prognostic impact of point mutations in the tyrosine-kinase domain 1 of FLT3 (FLT3-TKD mut) in patients (pts) with acute myelogenous leukemia (AML) remains controversial. Furthermore, co-occurrence of FLT3-TKD mut and mutated nucleophosmin-1 (NPM1 mut) was shown to have a favorable prognostic impact on AML pts receiving conventional chemotherapy. However, little is known about the outcome of AML pts with FLT3-TKD mut with or without co-occurring NPM1 mut treated with allogeneic stem cell transplantation (alloSCT). Patients and Methods This is a retrospective study of the acute leukemia working party (ALWP) of the European Society for Blood and Marrow transplantation (EBMT) investigating the outcome of adult AML pts with FLT3-TKD mut with or without NPM1 mut after first alloSCT using matched sibling (MSD), unrelated (UD) or haploidentical (haplo) donors between 2005 and 2022. All patients were in first or second complete remission (CR1 of CR2). Information on cytogenetic risk was necessary for inclusion. No ex-vivo T-cell depletion (TCD) was allowed. The primary endpoint was leukemia-free survival (LFS) at two years after alloSCT. Secondary endpoints were overall survival (OS), cumulative incidence of relapse (RI), non-relapse mortality (NRM), acute and chronic graft-versus-host disease (GVHD) and GVHD-free, relapse free survival (GRFS). One hundred and eighty-two adult AML pts with FLT3-TKD mut were identified, of which 74 (40.7%) had a co-occurring mutation in NPM1. Median age was 55.1 years (range 18.6-79.1) and 46.7% were male. Median follow-up was 21.4 months [IQR 13.6-28.1]. 78% of the pts were in CR1. Cytogentic risk was favorable, intermediate and adverse in 12.6%, 75.3% and 12.1% of pts, respectively. Additional FLT3 internal tandem duplication (FLT3-ITD) was present in 25.8% of pts. Information on measurable residual disease (MRD) was available for 68.7% of pts, being positive in 48% of these. Karnofsky performance score was < 90% in 21.1%, and hematopoietic cell transplantation-specific comorbidity index (HCT-CI) was >=3 in 28.1% of pts. 69.6% of pts were cytomegalovirus (CMV) positive. Conditioning was myeloablative in 52.8% and reduced intensity in 47.2% of pts. Stem cell donors were MSD, UD and haplo in 25.8%, 55.5% and 18.7% of cases. Stem cell source was bone marrow in 10.4%, peripheral blood in 87.4% and both in 2.2%. In-vivo TCD was performed in 59.2% of pts. GVHD prophylaxis was calcineurin inhibitor-based in 92.2% of pts. Results Engraftment was achieved in 99.4% of pts with a day-60 absolute neutrophil count (ANC) >0.5 x 10 9/L of 97.7% [95% CI: 93.7-99.2]. Day-180 rates of acute GVHD (aGVHD) grade II-IV and grade III-IV were 26.2% (95% CI:19.9-32.9) and 8.1% (95% CI:4.6-12.8), respectively. At two years, rates of total chronic GVHD (cGVHD) and extensive cGVHD were 30% (95% CI: 22.5-38) and 16.6% (95% CI:10.6-23.7), respectively. Two-year LFS and OS were 66.1% (95% CI: 57.6-73.2) and 74% (95% CI: 65.4-80.8), respectively. Two-year RI, NRM and GRFS were 22.5% (95% CI:16-29.8), 11.4% (95% CI: 7-17), and 51.1% (95% CI: 42.4-59.1), respectively. Cause of death was original disease in 47.5%, infection in 27.5%, GVHD in 22.5% and non-SCT related in 2.5% of cases. In univariate analysis the only factor with significant impact on LFS was donor type (haplo [n=34] vs. others, p=0.006). For GRFS, patient CMV negativity (p=0.014) and in-vivo TCD (p=0.01) were significant. Interestingly, co-occurring mutations in FLT3 (FLT3-ITD) or NPM1 were not identified as having a significant impact on LFS or GRFS. Moreover, MRD status before alloSCT was also not shown to have a significant impact on these outcomes. In multivariate analysis of LFS and GRFS, only donor type (haplo [n=34] vs. others) was shown to be significant for both endpoints, hazard ratio (HR) 2.54; 95% CI: 1.4-4.6; p=0.002, and HR 2.01; 95% CI: 1.18-3.41; p=0.01, respectively. Conclusion Acknowledging the limitations of our retrospective study in this rare entity results are encouraging given the high-risk population (median age 55.1 years, CR2 in 22%, co-occurring FLT3-ITD in 25.8%, positive MRD in 48%, HCT CI >=3 in 28.1%). LFS, OS and GRFS rates were 66.1%, 74% and 51.1%, respectively, and both RI and NRM were comparably low with rates of 22.5% and 11.4%, respectively. No positive prognostic impact of co-occurring mutations in FLT3-TKD and NPM1 was detected, unlike what was found for conventional chemotherapy.

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.

Allogeneic Hematopoietic Stem Cell Transplantation in Adolescents and Young Adults with Acute Lymphoblastic Leukemia - Retrospective Dual-Center Study

Background: Adolescents and young adults (AYAs) with acute lymphoblastic leukemia (ALL) are treated with various chemotherapy regimens. Some patients undergo allogeneic hematopoietic stem cell transplantation (HCT) due to high-risk genetic characteristics, chemo-resistant disease (failure to achieve timely measurable residual disease (MRD) negative remissions, or relapse or refractory disease. There is paucity of data on outcomes of AYA ALL patients receiving HCT. Methods: We performed a dual-center analysis of data from MD Anderson Cancer Center (MDACC) and Dana-Farber Cancer Institute (DFCI) to evaluate outcomes of AYA patients who received HCT for Philadelphia-negative (Ph neg) ALL and examined variables that might have an impact on these outcomes. We included all patients who received their first HCT between the ages of 15-40 years between the years 2010-2022. MRD status was evaluated using flow cytometry with a sensitivity of 0.01%. Acute and chronic graft versus host disease (GvHD) were classified according to consensus criteria. The primary endpoint was overall survival (OS), and secondary endpoints included progression rate and non-relapse mortality (NRM). Cox proportional hazards regression analysis was used to evaluate predictors of OS, and Fine and Gray regression for predictors of relapse and NRM. Competing risks were accounted for in analyses pertaining to progression and NRM. Results: A total of 376 Ph neg ALL AYA patients were included in the analysis, 247 from MDACC and 129 from DFCI. The median age at transplant was 25 (range 15-40) years, 39 patients (10%) were aged ≤18 years at time of HCT and 251 (67%) were males.The majority had B-ALL (n=282, 75%), 42 (11%) had complex karyotype and 28 patients (7%) had translocation (4:11). Most patients received either pediatric-inspired (48%) or hyper- cyclophosphamide, vincristine sulfate, doxorubicin, dexamethasone (CVAD) based (42%) frontline induction regimens, and the median time from diagnosis to HCT was 11 (range 2-283) months. At transplant, most patients were in CR1 or CR2 (44% each); 63% of patients achieved MRD negativity prior to HCT. Most patients received an HCT from a matched unrelated donor (MUD) (33%) or a matched sibling donor (MSD) (32%), and most patients received myeloablative conditioning (MAC) (79%) ( Table 1). The cumulative incidence of grade 2-4 acute GvHD and grade 3-4 acute GvHD at 6 months was 37% (95% CI 33%-42%) and 13% (95% CI 10%-17%), respectively. The cumulative incidence of chronic GvHD at 3 years was 28% (95% CI 23%-33%), with most patients experiencing either mild (39%) or moderate (36%) chronic GvHD, and 25% had severe chronic GvHD. For patients transplanted in CR1, CR2 and CR3/PD the estimated 3-year OS was 69% (95% CI 61%-77%), 53% (95% CI 44%-61%) and 29% (95% CI 16%-43%), respectively; the 3-year NRM rate was 9% (95% CI 5%-15%), 18% (95% CI 13%-25%) and 27% (95% CI 16%-43%), respectively; and the 3-year progression rate was 27% (95% CI 20%-35%), 36% (95% CI 29%-45%) and 48% (95% CI 36%-65%), respectively. In multivariate analysis, HCT in CR3/PD was associated with inferior OS (HR 4.3, p<0.001) and higher NRM (HR 2.3, p=0.04, Table 2), however there was no difference in survival between HCT at CR1 vs. CR2 (p=0.3); >2 lines of therapy prior to HCT was associated with inferior OS (HR 1.8, p=0.004) and higher rate of progression (HR 1.9, p=0.008); HCT-CI>3 was associated with inferior OS (HR 1.6, p=0.01) and higher NRM (2.3, p=0.004); positive MRD status prior to HCT was associated with inferior OS (HR 1.9, p=0.004) and higher rate of progression (HR 3.3, p<0.001); use of bone marrow graft was associated with lower rate of progression (HR 0.6, p=0.02) and use of a matched donor (MSD/MUD) was associated with lower NRM (HR 0.5, p=0.01). Conclusions: In this analysis of a large dual-center cohort of AYA Ph -ALL patients that received HCT, we found that patients transplanted in CR1 had the most favorable outcomes with 69% 3-year OS. Patients not in CR1/CR2, patients who received HCT after >2 lines of therapy and those with positive MRD pre-HCT had inferior OS on MVA. Although patients who received HCT at CR3/PD had inferior OS, an estimated one-third of patients were still alive at 3 years after HCT.