Sensitive, scalable and affordable measurable residual disease (MRD) assays are needed to guide treatment decisions in acute myeloid leukemia (AML), particularly around allogeneic hematopoietic stem cell transplantation (allo-SCT). Next-generation sequencing (NGS)-based MRD assays offer broad applicability and high sensitivity, but remain too costly for routine use in resource-limited environments. We developed a cost-efficient, sensitive NGS MRD assay utilizing single-molecule molecular inversion probes (smMIPs) targeting 92 genomic loci in 33 AML driver genes and applied it to 93 AML patients in remission prior to allo-SCT. MRD positivity, defined as the presence of ≥ 1 non-DTA (DNMT3A, TET2, ASXL1) gene variant with ≥ 0.5% variant allele frequency (VAF), was associated with significantly shorter post-transplantation overall survival (OS; p < 0.001). In multivariable analysis, NGS-based MRD detection remained an independent predictor of inferior OS (hazard ratio 4.58; p = 0.002). Conditioning intensity did not associate with outcome of MRD-positive patients in this retrospective cohort. Mutations at diagnosis and pretransplantation showed variable concordance across genes, and consistently lower VAFs at the later timepoint. In three patients, multiple low-VAF clustered variants in RUNX1 and TET2 were detected pre-transplantation, potentially indicating treatment-induced mutagenesis. These findings demonstrate that a broadly applicable, smMIP-based NGS MRD assay can provide clinically relevant risk stratification before allo-SCT in AML, while its low library preparation costs of approximately 8€ per sample may facilitate wide implementation in routine practice and allow more patients to receive MRD-directed therapeutic interventions.

Background: Lower-risk myelodysplastic neoplasms (LR-MDS) are a group of clonal bone marrow disorders characterized by ineffective hematopoiesis, leading to chronic cytopenias and a risk of progression to acute myeloid leukemia. Despite being classified as lower risk, many patients experience debilitating anemia and reduced quality of life, with limited durable treatment options available. Romaciclib is an orally bioavailable small molecule inhibitor targeting mediator complex kinases CDK8 and its paralog CDK19. Previously published research confirmed romaciclib's potential to induce erythroid differentiation at clinically relevant doses on patient-derived CD34+ cells with acquired MDS/AML-like genetic aberrations resulting in erythroid dysfunction (Mazan et al., EHA 2025; Pakulska et al., Blood, 2021). Available data provide a compelling argument to investigate romaciclib in patients with LR-MDS. Aims: The primary objective of the REMARK study is to evaluate the proportion of patients with LR-MDS who have an erythroid response (HI-E) according to IWG 2018 criteria following treatment with romaciclib. Secondary objectives include safety and tolerability of romaciclib as well as QoL assessments. Methods: REMARK (NCT 06191263) is an ongoing phase 2 open label study of romaciclib orally administered in patients with LR-MDS. Romaciclib is taken orally at a starting dose of 150 mg every other day (q.o.d). in a 21-day treatment cycle from day 1 to day 13 (total of 7 doses per cycle). Response assessment will be carried out in cycle 9 according to IWG 2018 HI-E criteria. Patients who had an HI-E response during the 24-weeks observation period but lost this response before C9D1 or patients who never achieved an HI-E response during the 24-weeks observation period may be placed on a higher dose of 250 mg at the investigator's decision. If the higher dose is started, they will undergo up to 8 additional cycles of treatment on the higher dose. All patients will undergo EOT and 3 months of follow-up after their last dose of RVU120 within the study. An interim analysis is pre-specified to assess the response in the first 21 patients. Results: At the time of abstract submission, a total of 42 patients started treatment in the REMARK study, and 15 patients are ongoing. Results of the interim analysis will be reported at the conference. Based on preliminary data, at least one patient with high transfusion burden at baseline (≥8 RBC units in 16 weeks) achieved a major erythroid response according to IWG 2018 criteria in the 24-weeks observation period. This male patient was carrying an SF3B1 mutation, and ringsideroblasts were present at baseline. He received three prior lines of therapy with ESA, luspatercept, and lenalidomide. The analysis of additional patients is ongoing, including molecular profiling at baseline and during treatment. No new safety signal was identified in the REMARK study. A total of 343 adverse events were reported in 42 treated patients. The most common events assessed as at least possibly related to RVU120 were nausea (64 events), vomiting (49), asthenia (13), and inappetence (12). These events were leading to study discontinuation in some patients. Summary/ Conclusions: Despite the preliminary nature of the data, initial signs of clinical activity of romaciclib in patients with LR-MDS were observed. Ongoing analyses in the study aim at describing the clinical and molecular changes during treatment with romaciclib, at identifying the optimal dose and schedule as well as potential predictors of response.

Background: The combination of Azacitidine (AZA) and Venetoclax (VEN) has become the standard of care frontline treatment for AML patients who are ineligible for intensive treatment due to advanced age or comorbidities, based on the results of the VIALE-A trial. While the combination regimen improved response rate and survival compared to AZA monotherapy, it also resulted in increased hematotoxicity. Among patients who had achieved a response in the VIALE-A trial, which used a standard regimen of 7 days (d) of AZA combined with 28 d of VEN, dose delays due to cytopenias were needed in 78%. Consequently, many clinicians have adopted shortened courses of VEN, either upfront or after a response is achieved, although this approach has not yet been evaluated in prospective trials. We hypothesized that AZA also contributes to the hematotoxicity of the VEN/AZA combination, and that shortening AZA administration from 7 d to 5 d per 28-day cycle could be another strategy to reduce toxicity while maintaining efficacy of the VEN/AZA doublet. Aims: VenAza-5S (NCT05833438)was a single-arm, multicenter Phase II trial designed to obtain initial data on the tolerability and safety of 5d of AZA combined with 28d of VEN in newly diagnosed AML patients ineligible for standard induction therapy. Methods: Eligible patients had newly diagnosed AML and were either ≥75 years of age and/or had comorbidities precluding treatment with intensive induction chemotherapy. Patients with acute promyelocytic leukemia or core binding factor-rearranged AML were excluded. All patients received AZA 75mg/m2 on d1-5 and VEN 400mg on d1-28 of each 28-day cycle. Guidelines for initial VEN ramp-up, VEN dose adjustments in the presence of CYP3A-inhibiting co-medications, and VEN and AZA dose reductions in the case of recurrent episodes of cytopenias corresponded to those used in the VIALE-A trial. The primary endpoint was the composite complete remission (cCR) rate, defined as the rate of complete remission (CR) or CR with incomplete hematopoietic recovery (CRi) after up to 6 cycles of therapy. Secondary endpoints included the overall response rate (ORR, comprising CR, CRh, CRi, and morphologic leukemia-free state [MLFS]), and event-free and overall survival (EFS/OS). Results: Between May 2023 and April 2025, 45 pts were enrolled at 11 sites in Germany. Data cut-off for the present preliminary analysis was June 23, 2025. Median patient age was 81 years (range, 66 to 91 years), and ECOG performance status was ≥2 in 33%. Twenty-two patients (49%) had AML with myelodysplasia-related changes, 21 patients (47%) had de novo AML, and two had AML post cytotoxic therapy. ELN-2022 risk was favorable in 3/45 (6.7%), intermediate in 17/45 (37.8%) and adverse in 22/45 (48.9%) patients (3 pts not evaluable). The median duration of cycles 1, 2 and 3 was 36 d, 30 d and 36 d, respectively. The cCR rate after up to six treatment cycles so far is 53.3% (24/45; 2 pts are not yet evaluable), and the ORR was 60% (27/45). Median time to follow-up was 11.5 months, and median OS is 11.1 months. Hematologic adverse events (i.e. neutropenia, anemia or thrombopenia) of Grade ≥3 occurred in 30 pts (67%). Grade ≥3 infections occurred in 17 participants (38%). Mortality at 30 d from study enrollment was 11% (5/45). Summary/Conclusion: In this high-risk patient population with a median age of over 81 years and nearly 50% myelodysplasia-related AML, the VEN + AZA-5 regimen achieved a cCR-rate of 53%. While in the VIALE-A trial, a cCR-rate of 66% was reported for the combination of VEN with 7d of AZA, a direct comparison is problematic given the differences in baseline patient characteristics. More detailed analysis of prognostic factors, responses in genetic subgroups including the ELN-2022 and 2024 risk categories, and molecular responses will be presented at the meeting. The VenAZA-5 regimen appears to be an effective and well-tolerated front-line treatment option for older or comorbid AML patients, and the 5-day schedule of AZA administration may be attractive for patients and physicians. Furthermore, this regimen may serve as a backbone for future combination therapies.

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.

Platzbecker U, Lane S and Adès L contributed equally. A study by the European Myelodysplastic Neoplasms Cooperative Group (EMSCO) Introduction: Hypomethylating agents (HMAs), either as monotherapy or combined with venetoclax (VEN), are standard of care for patients with higher-risk MDS (HR-MDS) or AML ineligible for intensive chemotherapy. However, most patients fail to respond or relapse. Outcomes for progress after HMA-based therapy remain poor, with limited effective options. Imetelstat is a potent selective telomerase inhibitor recently approved by FDA and EMA for transfusion-dependent lower-risk (LR) MDS patients ineligible or relapsed/refractory to ESA. Its clinical efficacy in HR-MDS or AML has not yet been established. Methods: The multicenter phase 2 IMpress trial (NCT05583552), led by EMSCO, evaluates safety and efficacy of imetelstat sodium in HR-MDS or AML patients refractory, relapsing or intolerant following at least 6 or 4 cycles of either azacitidine (AZA) or decitabine (DAC), respectively, or 3 cycles of VEN/AZA. In cohort 1 (ASH 2024), patients received 7.5 mg/kg i.v. once every 4 weeks for 4 cycles. Due to a lack of response and no new safety signals, the protocol was amended to biweekly dosing. The primary endpoint (PE) was overall response rate after 4 months (CR, CRi, PR, HI). All patients achieving CR, CRi, PR or HI after 4 months of imetelstat were considered responders and allowed to continue treatment until loss of response/disease progression. Non-responding patients stopped treatment after 4 months. Results: Between Aug-Dec 2024, 24 patients from 8 centers in Germany, France and Australia were screened for the second cohort. Of these, 23 (MDS=6, AML=17) received ≥1 dose of imetelstat. The median number of doses was 5/patient, compared to 3 in the first cohort. Median age was 77 years in both first (68–87) and second cohort (66–88). More male than fem. patients were enrolled, with 15M and 8F in the first cohort, and 14M and 9F in the second. The median ECOG performance status was 1 (0–2) in both cohorts. Complex karyotype was reported in 6/23 patients across both cohorts. Median percentage of bone marrow blasts at screening was 30% (8–91) in the first cohort and 27% (5.5–86) in the second. Prior treatment with VEN was reported in 47.8% (11/23) of the first cohort and 39.1% (9/23) of the second. In the second cohort, 6/23 reached the primary endpoint visit, scheduled after 4 cycles of treatment, compared to none in the first cohort: 3 had stable disease (SD) and 3 showed progressive disease (PD). One patient with SD achieved neutrophil response (HI-N) and received 3 additional doses in the extension phase. 13 of the 23 patients reached the first (preliminary) disease assessment after 2 cycles. At this point, only 1 patient showed a response (SD with HI-N), 9 patients had SD and 2 had PD. As of 17th June 2025, the median OS of the first and second cohort was 119 (95% CI: 83-144) and 102 days (95% CI: 67-TBD), respectively. The median PFS of the first and second cohort was 69 (95% CI: 57-113) and 92 days (95% CI: 57-TBD), respectively. In the second cohort, 24 SAEs occurred in 19 patients from August 2024 until 8th May 2025, of which none were deemed related to imetelstat. The most common SAEs were febrile neutropenia (n=6), disease progression/transformation to AML (n=4), sepsis (n=2) and fever (n=2). Overall, 11/24 SAEs resulted in death (n=4 disease progression or AML, n=2 cardiac/cardiorespiratory arrest, n=1 febrile neutropenia, n=1 sepsis, general health alteration and death of unknown reason). 8 of the SAEs resolved without sequelae and 2 remained unresolved. In the first cohort, 30 SAEs occurred in 18 patients, with 3 deemed possibly related to imetelstat (pneumonia [n=2], febrile neutropenia [n=1]). The most common SAEs were disease progression/transformation to AML (n=9), pneumonia (n=3), febrile neutropenia (n=3), and sepsis (n=2). 10/30 SAEs resulted in death. Despite higher drug exposure in the second cohort, no increase in toxicity was observed. Conclusion: Increased exposure to imetelstat in refractory, relapsing or intolerant AML/HR-MDS patients did not appear to be associated with additional toxicity. PE visit completion rose from 0/23 patients to 6/23 (26%) in the second cohort, despite only one achieving HI, and no marrow responses were observed. One patient remains on treatment, and 2 are in follow-up. Imetelstat has limited single agent activity in this very adverse prognosis group.

F I G U R E 2 Outcomes according to high (≥1%) or low (<1%) NPM1/ABL1 measurable residual disease (MRD) levels.(A) Time to relapse in relapsing patients (median time to relapse in patients with 0.01%-<1% NPM1/ABL1 burden at hematopoietic stem cell transplantation (HSCT): 159 days; median time to relapse in patients with ≥1% NPM1/ABL1 burden at HSCT: 75 days, (B) cumulative incidence of relapse and (C) overall survival.

Introduction: Even after allogeneic hematopoietic stem cell transplantation (HSCT) relapse remains a main driver of mortality in acute myeloid leukemia (AML) patients (pts). In overt relapse, treatment options are limited and survival is significantly shortened. Early detection of impeding relapse by monitoring measurable residual disease (MRD) could improve outcomes by identifying pts that would benefit from preemptive treatment. Most studies analyzing molecular MRD used mutation (mut) panels and did not differentiate between different genes. However, distinct genes may provide distinct prognostic relevance, as shown for ASXL1, DNMT3A, or TET2 (“DTA”) mut, which do not function as MRD markers after chemotherapy. Mut in IDH1 and IDH2 occur in up to 20% of AML pts, and cluster at three hotspots, making them potential easy targets for sensitive PCR-based MRD detection. So far, no larger study analyzed their relevance for MRD detection after HSCT. Methods: We screened 462 AML pts for IDH mut by NGS (MiSeq platform, Illumina) or Sanger sequencing and detected IDH mut in 100 pts (IDH1 R132: n=44; IDH2 R140: n=37; IDH2 R172: n=18; IDH1 R132 & IDH2 R140: n=1). At HSCT, IDH mut pts were in first complete remission with or without count recovery (CRc, 70%), second CRc (15%), or relapsed/refractory (15%). Median age at HSCT was 64 (range 20-76) years (y). Conditioning regimens were myeloablative (10%), reduced-intensity (30%) or non-myeloablative (60%). MRD analyses were performed by custom designed mut specific digital droplet PCR probe assays as published previously. IDH MRD positivity (MRDpos) was defined as VAF ≥ 0.05%. Median follow up after HSCT was 3.6 y. Results: Compared to all others,presence of IDH1 or IDH2 mut at diagnosis did not significantly associate with outcomes (cumulative incidence of relapse [CIR] P=.13, overall survival [OS] P=.40). In CRc prior to HSCT (n=66), 59% of IDH1 mut, 81% of IDH2 R140 mut and 38% of IDH2 R172 mut pts remained IDH MRDpos, which did not associate with CIR (P=.17) or OS (P=.80). In CRc after HSCT, the IDH MRD status was available for 57 pts (IDH1 R132: n=25; IDH2 R140: n=26; IDH2 R172: n=7) with a median of 4 samples/pt (range 1-21). 34% of IDH mut pts relapsed during follow-up, and all pts with available relapse material (n=16) were positive for their known IDH mut (median VAF at relapse 18.7%, range 0.09-29%). In all relapsing pts with samples available, relapse was preceded by at least one MRDpos sample (median VAF in first pos sample 0.23, range 0.07-19.9%). Median time from first MRDpos sample to overt relapse was 51 (range 8-341) days (IDH1: median 40.5 [range 8-119] days, IDH2: median 91 [range 13-341] days). Of the pts in ongoing CRc with post-HSCT samples available (n=40), 3 pts had 1 MRDpos sample (IDH1: 2 pts; IDH2 R140: 1 pt) and 1 pt had two MRDpos samples (IDH2 R172). In 2 pts these positive samples occurred directly after HSCT and converted to MRD negativity (MRDneg), 1 pt died from an acute infection 96 day after testing MRDpos and 1 pt converted to MRDneg after suffering from grade 3 acute graft-versus-host disease (GvHD). ROC curves showed that the IDH1 and IDH2 MRD status after HSCT were highly predictive of relapse within the next 56 days (AUCIDH1=.98 and AUC IDH2=.93) and 84 days (AUC IDH1=.91 and AUC IDH2=.90). Of note, ROC comparison showed that IDH1 and IDH2 MRD was not inferior in predicting relapse than the NPM1 MRD status within 56 days (AUCNPM1=.95, compared to IDH1: P=.19 and IDH2: P=.81) and 84 days (AUCNPM1=.81, compared to IDH1: P=.27 and IDH2: P=.35) in NPM1 mutated pts. Pts with at least one IDH MRDpos sample within the first year after HSCT had a significantly higher CIR (P<.001) and shorter OS (P=.001). This was also seen when IDH1 and IDH2 mut were regarded separately (IDH1: CIR P<.001 and OS P=.005; IDH2: CIR P<.001 and OS P=.07). Conclusion: Neither the IDH mut status at diagnosis nor IDH-based MRD in CRc prior to HSCT associated with outcomes.In contrast, after allogeneic HSCT, IDH1 and IDH2-based MRD reliably predicted relapse in AML pts and was not inferior to NPM1 mut based MRD. Our data indicates that all IDH mut only function as MRD marker after allogeneic HSCT, which resembles mut associated with clonal hematopoiesis, like DTA. This should be taken into account when assessing MRD in clinical practice. The conversion of MRDpos to MRDneg in pts early after HSCT or after suffering GvHD implies that immunological effects can eradicate MRD after HSCT.

Background: In acute myeloid leukemia (AML), clonal hematopoiesis (CH)-associated mutations usually appear early in leukemogenesis, and often persist in complete remission following chemotherapy. The presence of residual CH at the time of a consolidating allogeneic hematopoietic stem cell transplantation (HSCT) has no negative impact on outcomes of AML patients (pts). Here, we analyzed the prognostic impact of measurable residual CH (MRCH) early after HSCT. Results: In remission before HSCT 83% of pts remained MRCHpos, which did not associate with a higher cumulative incidence of relapse (CIR, P=.19) or shorter relapse-free survival (RFS, P=.08, with a trend for higher CIR in patients without persisting MRCH). Fifty-one (35%) pts relapsed after HSCT. In 29 of these pts material at relapse was available and showed that the CH mutation detected at diagnosis was also present in all but one relapse samples (median VAF at relapse of 11.8 [range 0.2-68.3]%). Of those, 25 pts had at least 1 post-HSCT sample available prior to relapse. In 22/25 pts, impeding relapse was preceded by detectable MRCH (first positive sample with a median VAF of 0.25 [range 0.06-12.3]) at a median of 55 days prior to morphologic relapse. In two non-converting (conversion from MRCHneg to MRCHpos) patients who relapsed, both with SRSF2 mutations, the last samples 132 and 35 days prior to relapse were MRCHneg. One non-converting patient suffered from an extramedullary relapse without bone marrow involvement. A total of 19% of pts died without relapse. Of the pts alive in remission, the majority remained MRCHneg (Figure 1A). At all evaluated timepoints post-HSCT, we observed a significantly higher CIR and shorter RFS for AML pts in morphologic remission who had detectable MRCH: at day 28 after HSCT (P=.01, and P<.001, respectively), day 100 after HSCT (P<.001, and P<.001, respectively, Figure 1B), day 180 after HSCT (P=.003, and P=.002, respectively), and day 360 after HSCT (P=.001, and P=.04, respectively). While the risk of relapse remained high in MRCHpos pts irrespective of the timepoint of assessment during post-HSCT follow-up (46-66% after 3 years), the 3-year risk of relapse in MRCHneg pts continuously decreased with time after HSCT (28% at day +28, 13% at day +100, 5% at day +180, 0% at day +360 in MRCHneg pts, respectively). Conclusions: In contrast to the absent prognostic relevance of persisting MRCH in remission before HSCT, the presence of detectable MRCH after HSCT was linked to a higher CIR and shorter RFS at every evaluated timepoint early after HSCT. The risk of relapse in MRCHneg pts continuously decreased within the first year after HSCT: the longer pts remained MRCHneg the less likely relapse occurred. Our data suggests MRCH as a feasible marker for residual disease assessment in AML pts in morphologic remission after allogeneic HSCT. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Introduction Non-relapse mortality (NRM) remains a relevant risk for acute myeloid leukemia (AML) patients (pts) undergoing allogeneic hematopoietic stem cell transplantation (HSCT). CT-defined body composition parameters are increasingly recognized as modifiable risk factors in cancer pts. Here, quantity and quality of skeletal muscle areas (SMA) as surrogate parameters for sarcopenia, and the amount of adipose tissue are associated with NRM. Large analyses in pts with hematological malignancies are scarce. We addressed this topic here in AML pts receiving HSCT. Methods We retrospectively analyzed 429 AML pts who received routine abdominal CT scans to exclude infectious foci up to 7 weeks prior to myeloablative (25%), reduced intensity (15%), or non-myeloablative (NMA, 60%) HSCT. Median age at HSCT was 59 (range 17-76) years (y) and pts were in 1st complete remission with/without blood count recovery (CRc, 65%), later CRc (17%), or relapsed/refractory (18%). European LeukemiaNet (ELN22) risk at diagnosis was favorable 22%, intermediate 27% and adverse 51%. Body composition parameters were determined in CT on the level of the third lumbar vertebra. SMA and visceral adipose tissue (VAT) were measured on a predetermined range of radiodensity expressed in Hounsfield Units using ImageJ software. SMA was divided by the body height squared to calculate skeletal muscle index (SMI). Muscle quality was defined by intramuscular adipose tissue content (IMAC), measured using the muscle radiodensity, divided by that of the subcutaneous adipose tissue - with a higher IMAC indicating lower muscle quality due to a higher adipose tissue portion. Cut-offs were determined using ROC curves in a test set (1/3 of pts) and validated in a confirmation set (2/3 of pts) randomly partitioned by sex. Results Pt characteristics and outcomes did not differ between the test and confirmation set (cumulative incidence of relapse [CIR] P=.52, NRM P=.79, OS P=.20). Of all pts, 69% were sarcopenic, defined by lower SMI (cut-off male [m] 52.36cm²/m²; female [f] 40.38cm²/m²). Pts with sarcopenia had a lower body mass index (BMI) at HSCT (P<.01), a lower IMAC (P<.01) and a lower VAT (P<.01). 13% of pts were viscerally obese, defined by higher VAT (cut off m 159.85cm2, f 106.26cm2). Pts with visceral obesity were older (P=.03), had a higher BMI at HSCT (P<.01), a higher SMI (P<.01) and higher IMAC (P<.01). They also had a higher incidence of a complex karyotype (CKT, P=.01), more SRSF2 mut (P=.03) and more often developed a chronic graft versus host disease (GvHD, P=.01) after HSCT. 69% of pts had low muscle quality, defined by higher IMAC. They were older (P<.01), had a higher BMI at HSCT (P<.01), a higher VAT (P<.01) and a higher SMI (P<.01). They also less frequently had de novo AML (P=.01), a higher incidence of a CKT (P=.03), more SRSF2 mut (P=.03) and worse ELN22 risk (P=.03). Pts with a high IMAC had a higher HCT-CI score (P=.02), more often received NMA HSCT (P<.01) and more often received HSCT from unrelated (P<.01) or mismatch donors (P<.01). After HSCT, they more often developed acute (P<.01) and chronic GvHD (P=.04). Outcomes did not differ significantly according to the presence of sarcopenia (CIR P=.14, NRM P=.08, OS P=.20). Viscerally obese pts had similar CIR (P=.29), but a higher NRM (P=.03) which translated in a trend for shorter OS (P=.06). Pts with high IMAC had similar CIR (P=.25), but higher NRM (P<.01) and shorter OS (P<.01). In multivariate analysis, low muscle quality (i.e. higher IMAC) and visceral obesity (i.e. higher VAT) remained prognostic for higher NRM (Hazard ratio [HR] 3.40, 95% confidence interval [CI] 1.67-6.94, P<.01 and HR 1.85, 95% CI 1.05-3.28, P=.04) after adjustment for ELN22 risk and a higher IMAC for shorter OS (HR 0.53, 95% CI 0.35-0.8, P<.01) after adjustment for remission status at HSCT. As the IMAC significantly associated with OS, but differed according to age and BMI at HSCT, we performed additional subgroup analyses. Here, a high IMAC had the highest impact on OS in younger pts (≤60y P<.01, less in pts >60y [P=.04]) and pts with a BMI ≤ 25kg/m2 at HSCT (OS P<.01), with a lower impact in overweight (P=.07) and none in obese pts (P=.40). Conclusions In AML pts undergoing HSCT, visceral obesity associated with higher NRM and low muscle quality with higher NRM and shorter OS. Strategies to improve mobilization, physical activity and nutrition during treatment should be investigated to improve outcomes of these patients.

Background: Persisting MRD is a strong prognostic factor in NPM1-mutated (mut) AML patients (pts) and a new risk factor according to the European LeukemiaNet (ELN) 2022 classification. Data on MRD relapse in morphologic complete remission (CR) after achievement of MRD-negativity (neg) in these pts is limited. Aims: To evaluate outcomes of NPM1-mut AML pts suffering MRD relapse after having achieved a MRD-neg CR. Methods: Among 82 NPM1-mut AML pts, 67 achieved a MRD-neg CR at ≥1 timepoint. Of those, 31 pts had a MRD relapse during/after 7 + 3-based chemotherapy (Ctx, n=29) or upfront azacytidine/venetoclax (aza/ven, n=2) and were retrospectively analyzed. Sequential NPM1 MRD analyses were performed in bone marrow or peripheral blood samples using custom digital droplet PCR assays. NPM1/ABL1 levels ≥0.01% were defined as MRD-pos. Median follow-up after MRD relapse was 1.4 years. Results: The median time from MRD-neg CR to MRD relapse was 93 (range 14-932) days. At the time of MRD relapse, 7 pts (23%) were still on treatment, 12 pts (39%) were under active surveillance after completion of Ctx and 12 pts (39%) had undergone allogeneic hematopoietic stem cell transplantation (HSCT). At MRD relapse first pos NPM1/ABL1 levels were median 0.036 (range 0.01-18.9)% and increased to a maximum of median 2.09 (range 0.01-122.4)% while still in morphologic CR. 17 pts (55%) suffered morphologic relapse after a median of 125 (range 28-510) days after MRD relapse and 2 pts (6%) suffered non-relapse mortality (NRM). Cumulative incidence of relapse (CIR) and overall survival (OS) 2 years after MRD relapse were 64% and 59%, respectively (Fig. 1A). CIR (P=.88) and OS (P=.60, Fig. 1B) after MRD relapse did not differ between pts with favorable (i.e. no FLT3-ITD) or intermediate ELN2022 (i.e. concurrent FLT3-ITD, Fig. 1B) at diagnosis, or between pts who did or did not receive a HSCT prior to MRD relapse (CIR P=.65, OS P=.90). All 7 pts who were still on treatment at MRD relapse continued their therapy (3 under consolidation, 1 under maintenance, 3 directly before HSCT). Of the pts under surveillance, 11 received no treatment for their MRD relapse (5 eventually suffered morphologic relapse), and 13 received preemptive treatment (5 within a clinical trial, 3 donor lymphocyte infusion, 2 aza/ven, 2 aza, 1 ven) after a median of 45 (range 26-181) days after MRD relapse (9 relapsed, 3 converted to MRD-neg CR, 1 died from NRM). Both, the NPM1/ABL1 levels at MRD relapse and the maximum in morphologic CR were significantly higher in pts receiving preemptive MRD-guided therapy than in those who did not (P=.03 and P=.001, respectively, Fig. 1C). There was no different CIR (P=.44) or OS (P=.10) in AML pts who continued their (planned) treatment, received a preemptive MRD-guided therapy, or surveillance alone (Fig. 1D). Of note, 12 pts received aza/ven-based treatments, 2 for MRD relapse and 10 later after morphologic relapse. Of the 11 ven-naïve pts, 10 achieved a second MRD-neg CR (4 after 1 cycle, 6 after 2 cycles), and 1 a morphologic CR after 1 cycle despite prior aza exposure in 7/10 pts. Summary/Conclusion: Outcomes of NPM1-mut AML pts with MRD relapse did not differ with regard to ELN2022 risk at diagnosis or prior to HSCT. In this retrospective analysis with heterogeneous preemptive treatments there was no benefit from MRD-guided therapy vs therapy for morphologic relapse. However, response rates to aza/ven in ven-naïve pts were promising irrespective of MRD/morphologic relapse or prior aza exposure. Our data underlines the need of studies testing if MRD-guided aza/ven improves outcomes in NPM1-mut AML pts with (MRD) relapse.Keywords: Molecular relapse, Minimal residual disease (MRD), AML

Although the presence of FLT3-ITD, as well as levels of the FLT3-ITD allelic ratio, have been described as prognostic factors in acute myeloid leukemia (AML), little is known about how the FLT3-ITD allelic ratio impacts patients' outcomes when receiving an allogeneic hematopoietic stem cell transplantation (HSCT). We analyzed 118 patients (median age at diagnosis 58.3, range 14.3-82.3 years) harboring FLT3-ITD, of whom 94 patients were consolidated with an allogeneic HSCT and included in outcome analyses. A high FLT3-ITD allelic ratio was associated with a higher white blood cell count, higher blood and bone marrow blasts, and worse ELN2017 risk at diagnosis. Patients with a high FLT3-ITD allelic ratio more often had NPM1 mutations, while patients with a low allelic ratio more often had FLT3-TKD mutations. Patients with a high FLT3-ITD allelic ratio were less likely to achieve a measurable residual disease (MRD)-negative remission prior to allogeneic HSCT and had a trend for a shorter time to relapse. However, there was no distinct cumulative incidence of relapse, non-relapse mortality, or overall survival according to the FLT3-ITD allelic ratio in transplanted patients. While co-mutated FLT3-TKD was associated with better outcomes, the MRD status at HSCT was the most significant factor for outcomes. While our data indicates that an allogeneic HSCT may mitigate the adverse effect of a high FLT3-ITD allelic ratio, comparative studies are needed to evaluate which FLT3-ITD mutated patients benefit from which consolidation strategy.

Background: The 2022 updated European LeukemiaNet (ELN) risk classification for acute myeloid leukemia (AML) includes risk adjustments during disease course by measurable residual disease (MRD) assessment. While the ELN2022 classification suggests MRD adjustment in patients (pts) with favorable (fav) or intermediate (int) risk, studies with regard to the utility of MRD also including the adverse (adv) risk group are pending. Aims: To evaluate the clinical value of the MRD status at allogeneic hematopoietic stem cell transplantation (HSCT) within all three diagnostic ELN2022 risk groups. Methods: We analyzed 229 AML pts who could be unambiguously classified according to the ELN2022 risk classification at diagnosis and underwent consolidating HSCT (median age 61.5, range 16.3-76.4 years) in first (78%) or second (22%) complete remission (CR) or CR with incomplete peripheral count recovery (CRi). Conditioning regimens were non-myeloablative (77%), reduced-intensity (7%), or myeloablative (16%). At diagnosis, cytogenetics, as well as the mutation status of 54 recurrently mutated genes were evaluated. All pts had blood or bone marrow remission material up to 28 days prior to HSCT available for MRD analysis based on NPM1 mutations or BAALC, MN1, or WT1 expression. MRD positivity was defined as being positive for any of the analyzed markers, and outcomes were analyzed for each ELN2022 risk group separately. Median follow up after HSCT was 3.9 years. Results: ELN2022 risk at diagnosis was fav (n=69), int (n=73), or adv (n=87). The percentage of pts attaining a MRD-negative (neg) remission did not differ significantly according to ELN2022 risk at diagnosis (fav 51% vs int 53% vs adv 61%, P=.40). A total of 38% of pts relapsed after HSCT with a significantly higher risk of relapse in MRD-positive (pos) than in MRD-neg pts (P<.001, Hazard Ratio [HR] 3.5 [range 2.2-5.5]) in the whole cohort. Regarding the diagnostic ELN2022 groups, the MRD status at HSCT significantly impacted the cumulative incidence of relapse (CIR) in all three groups (fav: P<.001, int: P<.001, adv: P=.002, Figure 1A-C). However, the relative risk of relapse for MRD-pos vs MRD-neg pts decreased with higher diagnostic ELN2022 risk: the HR for relapse was highest in ELN2022 fav (HR 17.4, range 2.2-139), lower in int (HR 5.3, range 2.3-12.1), and lowest in adv risk pts (HR 2.6, range 1.4-4.7, Figure 1D). Similarly, the c-statistics was highest in ELN2022 fav (0.78), lower in int (0.73) and lowest in adv risk pts (0.64, Figure 1E). While overall, the risk of relapse after HSCT increased with higher ELN2022 risk at diagnosis, this was especially seen in MRD-neg pts at HSCT (at 5 years, fav vs int vs adv: 3% vs 20% vs 39%) and less in MRD-pos pts at HSCT (43% vs 63% vs 72%). Similar results were observed when we excluded NPM1 based MRD from the analysis. In contrast, the time to relapse did not differ significantly between the three ELN2022 risk groups in MRD-neg (one pts after 27 vs median 346 vs median 131 days, P=.24) or MRD-pos (median 138 vs 93 vs 83 days, P=.25) pts suffering relapse. Summary/Conclusion: Although the MRD status at HSCT was a significant factor for CIR in all ELN2022 risk groups, the relative risk of relapse between MRD-neg and MRD-pos pts at HSCT depended on the ELN2022 risk at diagnosis and was lowest in ELN2022 adv risk pts. Especially MRD-neg pts with adverse diagnostic ELN2022 risk still had a high risk of relapse, most likely due to a higher “background” relapse risk of a more aggressive AML phenotype. This should be taken into account during clinical surveillance after HSCT.Keywords: AML, Clinical outcome, ELN, HSCT

Somatic mutations in the isocitrate dehydrogenase 1 and 2 genes (IDH1 and IDH2) are common in acute myeloid leukemia (AML). The prognostic impact of the presence of IDH mutations may be influenced by the comutational status, the specific location of the mutation (ie, IDH1 R132, IDH2 R140, and IDH2 R172) at diagnosis, and the dynamics of the mutation burden during disease course. Even though many patients with IDH-mutated AML are consolidated by hematopoietic stem cell transplantation (HSCT), the underlying biology and prognostic consequences remain largely unknown. Here, we present a large analysis of 292 patients with AML who received HSCT in complete remission (CR) or CR with incomplete peripheral recovery (CRi), in which we assessed the IDH mutation status at diagnosis and HSCT as a potential marker for measurable residual disease (MRD). About a quarter of all patients were IDH-mutated at diagnosis. The diagnostic presence of IDH mutations in AML did not have a significant prognostic impact when consolidated with HSCT. However, IDH1 R132 and IDH2 R172 MRD positivity in remission at HSCT associated with an increased risk of relapse, while IDH2 R140 mutations did not. The IDH2 R140 variant allele frequency (VAF) at diagnosis was higher, clustering around 50%, and the mutation clearance at HSCT in morphologic remission was much lower compared with IDH1 R132 and IDH2 R172. In our cohort, IDH2 R140 mutations behaved more like a clonal hematopoiesis-related aberration, while IDH1 R132 and IDH2 R172 harbored AML disease-specific features.

Topic: 22. Stem cell transplantation - Clinical Background: Recent identifications of sex-associated differences in the biology of hematologic neoplasm highlights the need to explore sex as a so far underestimated factor influencing outcomes. In unselected hematologic neoplasm, female sex had a beneficial impact on overall survival (OS) after HSCT. While HSCT remains the only curative treatment for high-risk AML patients (pts), data on sex-associated outcome differences in AML after HSCT remain sparse. Aims: To compare outcomes and risk factors of female and male AML pts undergoing HSCT at our center. Methods: We retrospectively analyzed 451 AML pts (216 female, 235 male) who underwent HSCT (median age 63, range 27-77 years) in first (78%) or second (22%) complete remission with or without blood count recovery. Conditioning was non-myeloablative (nma, 86%), or reduced intensity (ric, 14%) and donors were matched sibling (MSD, 15%), matched unrelated (MUD, 61%), mismatch unrelated (MMUD, 23%), or haploidentical (2%). At AML diagnosis, pts were grouped according to the European LeukemiaNet (ELN) 2022 risk. Up to 28 days prior to HSCT, NPM1 or RUNX1-based measurable residual disease (MRD) was analyzed in mutated pts (20%) using digital droplet PCR. Results: At diagnosis, female pts had higher blood (P=.004) and bone marrow (P=.008) blast counts, more de novo AML (P=.03), and less often harbored spliceosome mutations (i.e., SRSF2, U2AF1, ZRSR2; P=.02) than male pts, while ELN2022 risk at diagnosis (P=.40) and the MRD status prior to HSCT (P=.39) did not differ between female and male pts. After HSCT, female pts showed significantly shorter time to leukocyte regeneration (P=.03) and a higher incidence of chronic Graft-versus-Host-Disease (cGvHD, P=.02). MSD (P>.99) and MMUD (P=.26) were equally allocated between sexes. Regarding outcomes, female pts had similar non relapse mortality (NRM, P=.96) but significantly lower cumulative incidence of relapse (CIR, P=.05; Figure 1A), and longer overall survival (OS, P=.02; Figure 1B) than male pts. Important AML-associated risk factors as the ELN2022 at diagnosis (CIR P=.02 and P=.10; OS P=.04 and P=.03) and the MRD status at HSCT (CIR P<.001 and P<.001; OS P=.03 and P=.01) impacted outcomes in both, female and male pts, respectively. Analyzing the impact of HSCT-related variables, male pts transplanted from an MSD had a higher CIR compared to MUD/MMUD (P=.005) but lower NRM (P=.02), resulting in a trend for shorter OS (P=.10) for MSD, while CIR (P=.21), NRM (P=.53), and OS (P=.50) did not differ according to the used donor in female pts. The development of acute GvHD ≥ grade II associated with significantly higher NRM and shorter OS in female (P=.02 and P=.01, respectively) and male pts (P<.001 and P<.001, respectively, Figure 1C). In contrast, the development of cGvHD associated with lower CIR in female (P=.005) and male (P<.001) pts, but also a trend for higher NRM in female pts (P=.08), resulting in similar OS in female (P=.80), but improved OS in male (P<.001) pts developing a cGvHD. Interestingly, only male pts who developed cGvHD obtained OS comparable to those of female pts after HSCT (Figure 1D). Summary/Conclusion: We observed distinct AML characteristics as well as lower CIR and longer OS after HSCT in female compared to male pts. Female pts had higher cGvHD rates, but only in male pts, development of cGvHD significantly improved OS. Together with the higher CIR in male pts transplanted from MSD, this data implies an increased need of a Graft-versus Leukemia effect in male, compared to female pts after nma or ric HSCT.Keywords: Gender, AML, Allogeneic hematopoietic stem cell transplant, Clinical outcome