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Abstract Background: Older adults with newly diagnosed ALL treated with conventional chemotherapy have poor survival due to high rates of toxic death and disease relapse. The Alliance A041703 trial (NCT0373981) tested chemotherapy-free treatment with the anti-CD22 antibody-drug conjugate inotuzumab ozogamicin (InO) followed by the anti-CD19-CD3 bifunctional T-cell engager blinatumomab (blina) without maintenance in older adults to reduce toxicity and increase efficacy of therapy for this patient (pt) population. We previously reported with 22-month (mo) median follow-up that the study met its primary endpoint with a 1-year (yr) event-free survival (EFS) of 75% (90% confidence interval [CI] 63-89% lower bound exceeding null rate of 10%; JCO 2023 41, 7006). Here we report secondary outcomes with 45-mo median follow-up: 3-yr EFS, 3-yr overall survival (OS), response, and relapse characteristics. Methods: Eligible pts were ≥60 yrs old with newly diagnosed, Ph-negative, CD22-positive (≥20% of blasts) B-cell ALL without planned allogeneic HCT (alloHCT), liver disease, or CNS involvement at enrollment. Induction IA was InO 0.8 mg/m2 day (d) 1, 0.5 mg/m2 d8, d15 IV on a 21d cycle. Pts with adequate cytoreduction (marrow blasts reduced ≥50% or marrow cellularity ≤20%) after IA went to IB if in CR/CRi (InO 0.5 mg/m2 d1, d8, d15 IV; 28d cycle) or IC if no CR/CRi (InO 0.8 mg/m2 on d1 and 0.5 mg/m2 on d8 and d15 IV; 28d cycle). Those without cytoreduction to IA started course II blina. Pts without events in IA/B/C received course II blina continuous IV (9 mcg/d x 7d then 28 mcg/d x 21d; 14d break; 28 mcg/d x28d). Pts with CR/CRi to InO received 2 more 28d cycles of blina; others received 3 more. CNS prophylaxis was methotrexate 15 mg intrathecal x 8 doses. EFS was time from therapy start to failure to achieve CR/CRh/CRi by the end of course II, progression, relapse, or death, whichever occurred first, censored at last follow up. OS was time from registration to death from any cause censored at the last known alive date. Results: The median age of the 33 treated pts was 71 yrs (range 60-84). Eight pts had prior therapy for alternate malignancy in CR for >2 yrs prior to enrollment (6 multiple myeloma, 1 non-Hodgkin lymphoma, 1 breast cancer). Median CD22 expression was 92% (range 21-100%) and 49% had NCCN poor-risk genetics. Five pts underwent alloHCT in first CR/CRi and 2 pts received POMP maintenance after early discontinuation of blina (1 toxicity, 1 physician choice). The CR/CRi rate after InO was 85% (1 early death/refractory, 2 refractory, 2 undetermined due to low marrow cellularity on remission assessment marrow) with CR/CRi rate of 97% by completion of course II blina. With 45 mo median follow-up, the estimated 3-yr EFS was 48% (95% CI 33-70%) with a median EFS of 31 mo (95% CI 17.4-not reached [NR]) and no events after 31 mo. Sixteen events occurred: 12 relapses, 1early death, and 3 deaths in remission (1 encephalopathy, 1 relapse of multiple myeloma, 1 pulmonary complications after alloHCT). No isolated CNS relapse has been reported. Among relapses, 10 had immunophenotyping. Four (40%) were CD19-negative, one of which was also CD22-negative. Among CD19-negative relapses, genetics were hypodiploid (2), Pax5alt (1), and ZNF384-like (1, also CD22-negative). TP53 mutation or loss was observed in 5/12 (42%) relapses. Thirteen pts died. The estimated 3-yr OS was 59% (95% CI 44-79%) with median OS NR (95% CI 32-NR) with no deaths after 36 mo. In univariate analysis, EFS and OS were not impacted by age, gender, genetic risk (NCCN), prior therapy for alternate malignancy, or alloHCT in first remission. EFS was better with higher CD22 expression at diagnosis (≥90% vs <90%, 3-yr EFS 60% vs 25%, P=0.044). EFS and OS were worse for detectable minimal residual disease (MRD) at any timepoint by ASO-PCR. Undetectable MRD after course IA (1 cycle InO induction) was associated with EFS with a 3-yr EFS of 52% vs 0% for detectable MRD (median NR vs 8 mo, hazard ratio [HR] 0.07, P=0.004) and a 3-yr OS of 100% vs 0% for detectable MRD (median NR vs 20 mo, HR 0.00, P=0.0014). Conclusions: Longer follow-up of chemotherapy-free treatment with InO and blina for older pts with newly diagnosed, Ph-negative, CD22-positive, B-cell ALL reveals durable remissions and survival. The A041703 regimen is a compelling option for first-line treatment of this pt population. Support: U10CA180821, U10CA18088; https://acknowledgments.alliancefound.org.

Abstract Introduction: Clinical outcomes for patients (pts) with Philadelphia chromosome positive (Ph+) B-cell precursor Acute Lymphoblastic Leukemia (B-ALL) have significantly improved with the incorporation of tyrosine kinase inhibitors (TKI) and immunotherapy. Although the incidence of central nervous system (CNS) relapse in Ph+ B-ALL is rare, it has become an emerging challenge with chemotherapy-free approaches. While IKZF1, CDKN2A/B and emergence of T315I kinase domain mutations in ABL1 have been associated with worse outcomes (Foà R, JCO, 2024),further characterization of patients with CNS relapse could prove useful in risk stratification and optimizing treatment intensification. Currently, high white blood cell count (WBC) is being assessed as a marker to identify pts who may benefit from addition of CNS penetrant chemotherapy (ex. cytarabine or high-dose methotrexate (HD-MTX)) to TKI and immunotherapy protocols (Short NJ, J Hematol Oncol, 2025). Methods This is a multicenter retrospective study of relapsed/refractory Ph+ B-ALL pts under the COMMAND consortium. Age, gender, induction regimen and TKI of choice during induction were descriptively reported for the entire cohort. Categorical variables were compared, using Fisher's exact test, between pts with CNS relapse and pts with systemic relapse. Variables of interest were the presence of IKZF1 or CDKN2A/B alterations, emergence of T3151 mutation, CNS disease at diagnosis (dx), WBC >70K/microliter at dx, use of high-dose methotrexate (HD-MTX) during induction or consolidation, and use of TKI as part of the induction regimen. Odds ratio (OR) and 95% confidence intervals (CI) were reported for each variable. Results A total of 654 Ph+ B-ALL pts were initially identified across multiple centers in the United States, of whom 20 (3%) experienced a CNS relapse and 157 (24%) experienced a systemic relapse on median follow up of 29 months (range, 0-207). A total of 15 pts with CNS relapse and 114 pts with systemic relapse were used for this analysis after exclusion of pts without molecular data. The median age for the 129 pt cohort was 55 years (range 22-85), of whom 65 pts (50%) were male. Induction regimens used were intensive chemotherapy (IC)+TKI for 79 pts (61%), low-intensity chemotherapy or steroids (LDC-S)+TKI for 40 pts (31%), IC without TKI during induction for 5 pts (4%) and blinatumomab+TKI for 1 pt (1%). TKI of choice during induction included second-generation TKIs (dasatinib, nilotinib) for 77 pts (60%), imatinib for 30 pts (23%), ponatinib for 15 pts (12%) and none during induction for 5 pts (4%). CNS disease at dx was found in 6/15 pts (40%) with CNS relapse and 9/114 pts (8%) with systemic relapse, which was a statistically significant difference (p=0.002, OR= 7.57, 95% CI= 1.81 - 31.08). The systemic treatment regimens for the 15 pts with CNS disease at x were IC+TKI for 10 pts (66%) and LDC-S+TKI for 5 pts (33%), 9 of the pts (60%) received HD-MTX during induction. Intrathecal (IT) chemotherapy administration data at dx was available for 8 pts (53%) with CNS disease at dx, of whom 2 pts received <9 doses, 4 pts received 9-12 doses and 2 pts received >12 doses of IT chemotherapy. Although not statistically significant, pts with CNS relapse were more likely to have IKZF1 or CDKN2A/B alterations (p = 0.648, OR= 1.44, 95% CI= 0.14-7.78), WBC >70K/mcl (p = 0.472, OR= 1.73, 95% CI= 0.34-7.41), emergence of T3151 mutations (p = 0.123, OR= 2.54, 95% CI= 0.72-8.84) and use of HD-MTX during induction or consolidation (p = 0.262, OR= 2.15, 95% CI= 0.61-8.61); while they were less likely to have received a TKI during induction (p = 0.106, OR= 0.18, 95% CI= 0.02-2.34). Conclusion This data confirms that the presence of CNS disease at dx is associated with CNS relapse. Despite recent incorporation into clinical trials, WBC≥70K/mcl and omission of HD-MTX were not seen more frequently in pts with CNS relapse in this cohort. However, this analysis is limited by the small number of pts who experienced CNS relapse. With the rising use of chemotherapy-free regimens, prospectively trialing treatment intensification, such as with additional IT chemotherapy or HD-MTX, could be prospectively trialed in pts with CNS disease at dx to potentially improve outcomes for this subset of pts. The impact of increasing IT chemotherapy doses or additional cycles of systemic chemotherapy in this pt population is yet to be elucidated.

Abstract Venetoclax (Ven) in combination with hypomethylating agents (HMA) is widely used as frontline treatment in older or unfit patients with acute myeloid leukemia (AML). Liposomal cytarabine and daunorubicin (CPX-351) is FDA-approved for the treatment of secondary AML, including therapy-related (t-AML) and AML with myelodysplasia-related changes (AML-MR). The current study aimed to provide a comprehensive comparison between the two treatment strategies to better inform clinical decisions. Methods The current retrospective analysis was performed under an institutional review board approved minimal risk protocol at Mayo Clinic (MN, AZ, FL). AML-MR gene mutations or cytogenetic abnormalities were categorized according to the International Consensus Classification (Arber et al. Blood 2022;140:1200). Treatment response was assessed according to the 2022 European LeukemiaNet (ELN) criteria (Dohner et al. Blood 2022;140:1345). Overall survival (OS) analysis was censored for allogeneic stem cell transplant (ASCT). Statistical analyses were performed using JMP Pro (Version 18.0.0). Results A total of 600 patients with newly diagnosed AML (ND-AML) treated with CPX-351 (N-112, 19%), or Ven-HMA (N=488, 81%) were included. AML subtypes included de novo (N=277, 46%), post-myelodysplastic syndrome (post-MDS, N=114,19%), post-myeloproliferative neoplasm (post-MPN, N=70, 12%), post-MDS/MPN (N=36, 6%), t-AML (N=103, 17%) and AML-MR (N=274, 46%). Compared with those treated with Ven-HMA, patients receiving CPX-351 were younger (median age 65 vs 73 years; p<0.01), more likely to be female (50% vs 38%; p=0.02), more frequently diagnosed withsecondaryAML (68% vs 51%; p<0.01), and less likely to have NPM1MUT (5% vs 12%; p=0.02) whereas ELN 2022 cytogenetic risk distribution was similar between the two (adverse risk; 43% vs 40%; p=0.5). Comparison of treatment response and survival Complete response rates with (CR) or without (CRi) count recovery were similar between CPX-351 and Ven-HMA overall (55% vs 60%) as well as specifically in patients with AML-MR (60% vs 63%), adverse karyotype (44% vs 44%), NPM1MUT (100% vs 89%), TP53MUT(32% vs 45%), IDH1MUT (60% vs 76%), IDH2MUT (63% vs 77%), SF3B1MUT(71% vs 45%), and CBLMUT (33% vs 69%) [p>0.05 in all instances]. Compared to those with CPX-351, CR/CRi rates with Ven-HMA were superior in males (60% vs. 45%; p=0.04) and in patients with de novo AML (68% vs. 50%; p=0.03), STAG2MUT (86% vs. 44%; p=0.02), or CEBPAMUT (88% vs. 50%; p=0.03); infectious complications were significantly more frequent with CPX-351 (83% vs 62%, p<0.01). At a median follow-up of 12 months (range; 1-88), 416 (69%) deaths, 179 relapses (44% in CPX-351 and 52% in Ven-HMA responders) and 149 ASCTs (53% in CPX-351 and 18% in Ven-HMA) were documented. OS rates were similar between CPX-351 and Ven-HMA, in general (median 10 vs 13 months), as well as in patients with adverse karyotype, TP53MUT, IDH1MUT, and IDH2MUT (p>0.05 in all instances). By contrast, OS was superior in Ven-HMA-treated patients with post-MDS AML (median 12 vs. 7 months; age-adjusted p=0.02) and in CPX-351-treated patients harboring SF3B1MUT(median not reached vs 14 months; age-adjusted p<0.01). In addition, a borderline-significant OS advantage for CPX-351 was apparent in patients with PTPN11MUT (13.5 vs 8 months; p=0.08). Comparison in ICC defined AML-myelodysplasia-related CR/CRi and OS rates were comparable between patients treated with CPX-351 (N=57) or Ven-HMA (N=217), with response rates of 60% vs 63% (p=0.68) and median OS of 10 vs 14 months (p=0.61), respectively. However, OS was superior with Ven-HMA in patients with post-MDS AML (15 vs 8 months; age-adjusted p=0.02) and with CPX-351 in those with SF3B1MUT (NR vs 14 months; age-adjusted p=0.02). Conclusions: The current study suggests that Ven-HMA was as effective and possibly less toxic than CPX-351 for the treatment of ND-AML, including AML-MR, despite the bias for younger and fitter patients treated with the latter regimen. Observed differences involving patients with SF3B1MUT or post-MDS AML require validation in prospective studies and provide parameters for developing treatment-specific predictive models that will be presented at the meeting.

Abstract Background: The primary goal of induction therapy in acute myeloid leukemia (AML) is to induce complete remission with (CR) or without (CRi) hematologic recovery. In order to accomplish this, re-induction might be necessary based on D14-residual AML. The current study examines the impact of re-induction on relapse, transplant-censored survival, and post-transplant survival in a consecutive series of AML patients who have achieved CR/CRi following intensive chemotherapy. The study also examined the impact of variations in consolidation chemotherapy including the use of anthracycline-based chemotherapy (AC) in the first consolidation cycle and the use of high (HiDAC) vs. intermediate (IDAC) dose cytarabine. Methods: The current study was conducted under IRB-approved minimum risk protocols that allowed retrospective collection and analysis of patient data. Formal criteria were used for AML diagnosis, genetic risk stratification, and adjudication of response (Blood 2022;140:1345). Patients who received less intensive induction regimens or failed to achieve CR/CRi were excluded. Relapse-free (RFS) and overall survival (OS) analysis was calculated from the date of documented CR/CRi. Patients who underwent allogeneic stem cell transplant (ASCT) were censored at the time of transplant. Conventional statistical methods were utilized (JMP Pro 17.1.0, SAS Institute, Cary, NC, USA). Results: A total of 279 AML patients diagnosed between 2004 and 2020 were included: median age 58 years, males 60%, de novo 75%, post-chronic myeloid neoplasm (post-CMN) 16%, and therapy-related 9%. Induction regimens included idarubicin (Ida) + cytarabine (Cyt) in 183 (66%) patients, daunorubicin (Da) 60 mg/m² + Cyt in 76 (27%), and Da 90 mg/m2 + Cyt in 19 (7%). Re-induction was utilized to achieve CR/CRi in 72 (27%) at a median of 18 days from start of first induction regimen. The indication for re-induction was based on residual bone marrow blast (median 30%; range 4-90) on day14 (N=53) or day 21-28 (N=15), persistent extramedullary disease (N=2) or the presence of circulating blast (N=2). At a median transplant censored follow-up of 26 months (mos), 93 (33%) deaths, 117 (42%) relapses, and 134 (48%) ASCTs were documented; ASCTs were performed in CR1 (50%) or CR2 (50%). Median RFS was 18 mos, with respective 1-, 2-, 3- year RFS of 63%, 42% and 35%. In multivariable analysis (MVA), age ≥65 years (HR 1.5, p=0.04), European LeukemiaNet (ELN) adverse karyotype (vs. intermediate HR 1.7, p=0.02; vs. favorable HR 2.8, p<0.01), and the need for re-induction to achieve CR/CRi (HR 1.7, p=0.01) were independently predictive of relapse. RFS was not impacted by NPM1 mutation ( HR 0.5, p=0.09) or FLT3-ITD (HR 1.3, p=0.3). The median OS was 80 mos, with 5-year OS of 53%. In MVA, age ≥65 years (HR 2, p=0.01), ELN adverse karyotype (vs. intermediate HR 3.3, p<0.01; vs. favorable HR 4.7, p<0.01), FLT3-ITD (HR 1.9, p=0.04), and the need for re-induction (HR 1.9, p=0.03) independently predicted inferior OS. RFS was similar among patients who received AC (N=84; Idarubicin 9 mg/m2 or Da 60 mg/m2 days 1 to 2/3 + 100 mg/m2 Cyt days 1 to 5/7; median 18 mos) as their first consolidation cycle vs. those who received HiDAC (N=99; 3 g/m2 q12 hours on days 1,3 and 5; median 16 mos) or IDAC (N=58; IDAC; 1-2 g/m2 q12 hours on days 1, 3 and 5; median 24 mos; p=0.9); the corresponding median OS were 125, 85, and 40 mos (p=0.4). In patients aged ≥65 years, but not younger patients, both RFS (p<0.01; median 23 (N=36) vs. 8 (N=24) mos) and OS (median 40 vs. 12 mos, p<0.01) were significantly longer with IDAC vs. AC as their first consolidation cycle. In the AC consolidation cohort, patients who received 2-3 additional HiDAC/IDAC cycles displayed longer OS (p<0.01) and RFS (p=0.047), compared to those who received less. In both the HiDAC and IDAC cohorts, RFS and OS were not significantly different between those who received 3-4 versus 1-2 consolidation cycles. The need for re-induction did not affect post-transplant survival (p=0.5), which was superior in patients receiving Ida + Cyt induction (vs. Da 60mg/m2 + Cyt, HR 0.6, p=0.04) and in those transplanted in CR1 (HR 0.5, p<0.01). Conclusions: The current study signals the need for re-induction to achieve CR1 as a negative predictor of outcome in AML patients achieving CR/CRi following intensive induction chemotherapy. The particular information is potentially actionable in terms of the choice of consolidation strategy.

Abstract Introduction:A comprehensive integration of significantly mutated genes and pathways with molecular subgroups is lacking in adult B-ALL. Furthermore, the genomic drivers underlying each subgroup remain to be identified.We aimed to perform genomic analysis on a large cohort of patients with adult B-ALL, and to correlate genomic markers with achievement of MRD negativity enabling blinatumomab randomization, and with subsequent response to blinatumomab. Methods:For genomic analysis, we studied 569 adults with newly diagnosed B-ALL registered for initial screening on the ECOG-ACRIN-led E1910 trial (NCT02003222), which evaluated the addition of blinatumomab to standard consolidation chemotherapy. The median age was 52 yrs (range 30 to 71 yrs), with 52% males. Analysis was performed on tumor and matched-normal samples using whole transcriptome sequencing (RNA-seq; tumor only; n=569), whole exome sequencing (n=490), whole genome sequencing (n=131), and single nucleotide polymorphism array (n=445). B-ALL cases were classified into 22 molecular groups. Outcome analysis was limited to patients enrolled and treated on E1910 (n=319). Results: Driver genes (n=268) were identified by the mutation-significance detection tool dNdScv or by the presence of pathogenic variants in known cancer genes, with NUP188 identified as a novel driver gene. Recurrently mutated pathways included: B-cell development (46%), cell cycle (44%), epigenetic regulation (30%), other transcriptional regulation (27%), Ras signaling (25%), RNA machinery (17%) and JAK-STAT signaling (8%). A high frequency of high-risk subtypes was observed including BCR::ABL1 (20%), BCR::ABL1-like (18%), low hypodiploid (14%) and KMT2A (12%). Using tSNE analysis, we identified a new cluster of cases (n=20, 3.5%) lacking a known subgroup driver, with overexpression of CEBPA (n=13) or CEBPB (n=7), distinct from CEBPE/ZEB2, termed “CEBP-altered” ALL (CEBPalt). Five of 13 cases with high CEBPA expression harbored an IGH::CEBPA rearrangement and one harbored a RXRA::CEBPA enhancer hijacking alteration. Of the 7 cases with high CEBPB expression, 5 harbored IGH::CEBPB, and two of these had concomitant clonal BCR::ABL1 fusions. To identify additional mechanisms of CEBP deregulation, in situ Hi-C coupled to H3K27 acetylation immunoprecipitation (HiChIP) was performed on 5 cases. Four cases showed evidence of de novo CEBPA enhancer activity. In two cases, we identified novel insertions (12 and 34nt) ~2kb downstream of CEBPA. A novel translocation and enhancer hijacking event between LINC00426 and the 5' UTR of CEBPB was identified in the remaining case. Overall, we confirmed genomic alterations of CEBPA or CEBPB in 16 of 20 cases with available material. Thus, we have identified a new molecular subgroup of adult B-ALL characterized by genomic alterations that drive enhancer hijacking and oncogenic deregulation of CEBPA/CEBPB. Several subgroups were enriched in patients that failed induction chemotherapy (n=62) or were MRD-positive (n=63) compared to those that achieved MRD-negative status (n=194): BCR::ABL1-like (30 vs 14%, p<0.001), KMT2A (18 vs 9%, p=0.03) and BCL2/MYC (5 vs 1%, p=0.06). Conversely, the following subgroups were enriched in patients that achieved MRD-negativity: PAX5alt (6 vs 18%, p=0.002), TCF3::PBX1 (0 vs 5%, p=0.01) and ZNF384 (2 vs 6%, p=0.08) Within each molecular subgroup we compared the survival of patients who achieved MRD-negative status after induction and were randomized to receive blinatumomab plus chemotherapy (n=93) or chemotherapy only (n=91). Although numbers were low, blinatumomab improved relapse-free survival for patients with hyperdiploid, PAX5alt, BCR::ABL1-like and KMT2A ALL compared to chemotherapy alone. Clonal hematopoiesis of indeterminate potential (CHIP)-related gene mutations were identified in 121 of 417 cases analyzed (29% total: somatic 74%, remission 31%, both 5%). TP53 mutations were most frequent (n=65 patients), with the majority identified in patients with low hypodiploid (n=52). Interestingly, patients with CRLF2 rearrangements collectively harbored the highest number of other CHIP gene mutations (n=13), including DNMT3A (n=4), TET2 (n=3) and ASXL1 (n=3). Conclusions:We provide a comprehensive landscape of genomic alterations in adult B-ALL and identify a new group characterized by deregulation of CEBPA/CEBPB (CEBPalt). We also provide insights into the efficacy of blinatumomab in different molecular subgroups of adult B-ALL.

Abstract Background: VEXAS (Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic) syndrome is a hemato-inflammatory syndrome due to somatic mutations in UBA1 gene. Recently, DNA methyltransferase inhibitors (specifically, 5-azacitidine) and allogeneic hematopoietic stem cell transplantation (alloHSCT) have shown success in eradication of UBA1 clones and clinical remission in some patients. This study aims to provide a comparative efficacy analysis between DNA methyltransferase inhibitors (hypomethylating agents/HMA) versus alloHSCT in VEXAS syndrome patients. Methods: This is a multi-center, retrospective cohort study. UBA1 mutations were detected either through next generation sequencing [NGS, limit of detection (LOD) 2% variant allele fraction (VAF)] or quantitative droplet digital polymerase chain reaction testing (ddPCR, LOD 0.5% VAF). Outcomes of interest included overall survival (OS), glucocorticoid (GC) discontinuation/reduction in dose (prednisone < 10 mg/day), and complete molecular remission (CMR, defined as an undetectable UBA1 mutation). OS was calculated from the time of diagnosis to death or last follow up. Cumulative incidence of reduction in GC dose was calculated using competing risk analysis after accounting for death. Results: Between years 2020-2024, a total of thirty-nine male patients (median age 67, range 45-82 years) with VEXAS syndrome, necessity for therapy (GC-refractory inflammation and/or progressive marrow failure/myeloid neoplasm) and confirmed UBA1 pathogenic mutation were included. Of these, 18 (46%) received HMA therapy (5-azacitidine 72% and Decitabine 28%) with a median of 4 (range 1-36) cycles. and 21 (54%) underwent alloHSCT (MSD=4, MUD=12, MMUD=2, and haploidentical=3), all received reduced intensity conditioning (Flu/Mel =11, Flu/Bu=5, Flu/Cy/TBI=2, and TBF=3) and 91% received post-transplant cyclophosphamide-based graft-versus-host disease (GVHD) prophylaxis (only 2 patients in alloHSCT group received prior HMA without benefit). Baseline characteristics were well-balanced between HMA and alloHSCT groups; age at treatment (median 70 vs 65 years, p=0.2), and UBA1 M41V subtype (25% vs 40%, p=0.3), cytogenetic and non-UBA1 mutation abnormalities (p=0.4), prior lines of therapy (median 4 in both, p=0.5), time from diagnosis to therapy (median 7 vs 13 months, p=0.15), indication for therapy (p=0.12), Charlson CI scores (median 4 in both, p=0.4) and HCI-CI scores (median 4 in both, p=0.7). At a median follow-up of 45 (range 7-57) months, 11 (28%) deaths (alloHSCT=3 and HMA=8) were documented. Causes of death included infections (n=6), cardiac disease (n=2), poor graft function (n=2) and pulmonary GVHD (n=1). Compared to HMA therapy, alloHSCT group demonstrated higher rates of GC discontinuation (52% vs 6%, p<0.01) and CMR (evaluable= 22, 100% vs 50%, p<0.01). In the HMA group, 50% (n=9) discontinued therapy after a median of 4 months due to infectious complications or lack of benefit. In the alloHSCT group, 3 (14%) patients developed grade 2 acute GVHD (1-skin, 2-gut, no grade 3-4 acute GVHD) and 4 (19%) experienced moderate to severe chronic GvHD (2-lung, 2-mucocutaneous). In multivariable analysis (MVA) adjusted for age and HCT-CI, alloHSCT was identified as the strongest favorable predictor for OS (HR 0.18 95% CI 0.04-0.8) with similar results when analysis was restricted to transplant-eligible patients < 75 years of age (HR 0.1, 95% CI 0.03-0.6). In a 6-month post-treatment landmark analysis (n=31 evaluable), patients who underwent alloHSCT (n=17) exhibited numerically superior GC discontiuation rate (29% vs 14%, p=0.049) and subsequent OS compared to HMA (2-years OS: 84% vs. 61%, median not reached vs 25 months, 95% CI: 0.06–1.7). In a post-treatment competing risk [GC dose reduction (death)] analysis alloHSCT was associated with superior 2-, and 3-year rates of 57% (10%), and 76% (10%), compared to HMA 22% (24%), and 31% (42%) [p<0.01 (0.04)]. AlloHSCT was also associated with higher rate of CMR (evaluable= 21, alloHSCT N=16 and HMA N=5, 100% vs 60%, p=0.01). At the last follow up, none of the patients who achieved CMR had re-emergence of the UBA1 clone (despite early mixed chimerism). Conclusions: This study represents the largest comparative analysis of alloHSCT versus HMA therapy in VEXAS syndrome, and confirms superiority of alloHSCT in achieving molecular remission, GC discontinuation/dose reduction, and overall survival. Prospective clinical trial confirmation is warranted.

Abstract Introduction The European Leukemia Net (ELN) 2022 stratified acute myeloid leukemia (AML) patients (pts) treated with intensive chemotherapy (IC) into three groups based on genetic features. ELN 2024 (Döhner et al, Blood) and Beat AML 2024 (Hoff et al, Blood Advances) proposed revised systems to better capture the impact of genetic features in pts receiving less-intensive therapy (LIT). Real-world validation across treatment settings, including allogeneic hematopoietic stem cell transplantation (allo-HCT), is warranted. Methods We evaluated the performance of ELN 2022, ELN 2024, and Beat AML 2024 among AML pts treated at Mayo Clinic from 2016 to 2025. Only treated pts with available molecular data included. Response was assessed according to the ELN 2022 criteria. Overall survival (OS) was calculated from diagnosis. Multivariable Cox proportional hazard (CPH) models were used to adjust for covariates. Model performances were assessed using Harrell's c-index. Results 426 AML pts (median age 68 years; 60% male) were included; 195 (46%) received IC and 231 (54%) received LIT, while Allo-HCT was performed in 133 (31%) pts. Complex karyotype was present in 126 (30%) and normal cytogenetics in 143 (34%) pts. Molecular mutations included TP53 (20%), TET2 (18%), DNMT3A (16%), SRSF2 (16%), RUNX1 (16%), ASXL1 (16%), and NPM1 (15%). Among evaluable pts (83%), complete remission (CR) after first-line therapy was achieved in 47%. Risk group assignments varied: ELN 2022 vs. ELN 2024 classified pts as favorable (20% vs. 55%), intermediate (20% vs. 24%), and adverse (60% vs. 20%); Beat AML 2024 categorized pts as favorable (41%), intermediate (21%), and adverse (38%). ELN 2024 reclassified 229 (54%) pts of whom 5% upstaged and 49% downstaged, primarily affecting ELN 2022 adverse (67%) and intermediate (46%) groups. Among LIT-treated, CR rates did not differ across groups in any classification. Per ELN 2024, CR was achieved in 43% (favorable), 67% (intermediate), and 29% (adverse) of the LIT-treated pts. However, among IC-treated pts, CR was higher in favorable/intermediate vs. adverse groups across all models (p<0.0001). Allo-HCT was most common in ELN 2024 intermediate (41%) and favorable (32%) vs. adverse (16%) groups. Median OS (months; 95% CI) for the entire cohort was 15.7 (12.5–20.9) with median follow-up time of 49.8 (40.9-55). By ELN 2022, OS of the entire cohort was 49.4 (30.7–NA) for favorable, 50.0 (29.2–NA) for intermediate, and 8.8 (7.7–11.2) for adverse (p<0.0001). Per ELN 2024, OS of the entire cohort was 25.4 (18.5–37.3), 20.3 (13.4–39.8), and 5.7 (3.4–8.2), respectively (p<0.0001). Beat AML 2024 stratified OS of the entire cohort as 42.5 (30.7–NA), 11.4 (9.3–16.7), and 5.6 (3.5–8.0) for favorable, intermediate, and adverse groups (p<0.0001). ELN 2024 stratified the OS of the pts treated with LIT as 15.7 (10.1-24.9), 8.0 (4.9-13.9), and 6.8 (3.4-10.2) for favorable, intermediate and adverse risk groups, (p <0.0001). Among ELN 2022 adverse-risk pts, those reclassified as favorable per ELN 2024 had superior OS (15.0, 9.8–22.7) compared to intermediate (7.8, 5.0–9.3) or adverse (5.4, 3.3–8.0) risk groups, p<0.0001. C-index (95% CI) for OS in the entire cohort was highest for Beat AML 2024 (0.658, 0.629–0.688), followed by ELN 2022 (0.627, 0.599–0.655), and ELN 2024 (0.600, 0.568–0.631). In LIT-treated pts, ELN 2024 (0.597, 0.558–0.637) and Beat AML 2024 (0.586, 0.545–0.627) outperformed ELN 2022 (0.559, 0.521–0.596). Among allo-HCT pts, regardless of treatment type, ELN 2022 (0.610, 0.539–0.681) performed better than ELN 2024 (0.568, 0.487–0.648). In multivariable CPH models adjusted for age, bone marrow blasts, treatment intensity, and complex karyotype, ELN 2022 and ELN 2024 adverse-risk groups had higher hazard of death (HR 2.4, 1.6–3.5 and HR 1.7, 1.1–2.5, respectively, vs. favorable). No significant difference was observed between intermediate and favorable risk for ELN 2022 (HR 1.4, 0.9–2.2) or ELN 2024 (HR 1.4, 0.9–1.9). Allo-HCT was associated with a lower hazard of death (HR 0.4, 0.3–0.5). Conclusions In this real-world AML cohort, ELN 2024 and Beat AML 2024 improved OS prediction in LIT-treated pts compared to ELN 2022. This advantage was not observed in allo-HCT pts. Multivariable analysis confirmed the adverse-risk group as having the worst prognosis across all models. These findings highlight the importance of aligning molecular risk stratification with treatment modalities to enhance prognostication in AML.

Abstract Background Missense mutations in IDH1 are well-established therapeutic targets in acute myeloid leukemia (AML). In contrast, the synonymous IDH1 variant p.Gly105Gly (rs11554137), present in 5–10% of AML cases, has been considered a benign polymorphism due to its high population frequency (5.7% overall, 0.7–10.5%) and lack of protein-altering effect. However, prior studies have associated this variant with inferior outcomes (Wagner, J Clin Oncol, 2010), though findings have been inconsistent. Few studies have examined its prognostic significance in the context of treatment intensity or allogeneic stem cell transplantation (SCT). Methods With IRB approval, clinical and genomic data were extracted from the Mayo Clinic AML database for patients diagnosed between Jan 1, 2018, and Jan 31, 2025. Patients were stratified by IDH1 Gly105Gly (rs11554137) status via NGS on bone marrow. Outcomes included co-mutation profiles, treatment response, measurable residual disease (MRD) by multiparametric flow cytometry, and survival. Multivariable Cox and logistic regression models for relapse-free survival (RFS) and overall survival (OS) were adjusted for age at diagnosis, ELN 2022 risk category, and SCT conditioning regimen. Results Among 379 AML patients, 36 (9.5%) harbored the IDH1 Gly105Gly (rs11554137) variant (cases) (median VAF 49%, IQR 48–49.2). In the full cohort, median age was 68 years (IQR 59–74), M:F ratio was 1.5; 75% had de novo AML, and median follow-up was 52 months. Among cases, common cytogenetic abnormalities included complex karyotype (28%), del(7q) (14%), and trisomy 8 (6%), while frequently mutated genes included DNMT3A (19%), IDH2 (17%), and BCOR (14%). Of 345 treated patients, 43% received intensive, and 56% received low-intensity regimens, including hypomethylating agent (HMA) alone (n=13), HMA+venetoclax (n=159), and targeted therapy (n=7). Among cases, complete remission (CR) rates were higher with intensive vs. low-intensity therapy (70% vs. 17%, p=0.03). MRD positivity post induction was more common in cases (66% vs. 26%, p=0.01), suggesting suboptimal leukemic clearance. Among 103 patients who underwent allogeneic SCT in CR1 (47% received myeloablative conditioning), morphologic relapse occurred in 64.3% of cases compared to 23.6% of controls (p = 0.004). Cases experienced significantly inferior median RFS (8 months [95% CI 5–NA] vs. not reached for controls, p <0.001), indicating more durable post-SCT remission in the control group. In a multivariable Cox proportional hazards model adjusting for age, ELN risk, conditioning intensity, MRD status, and complex karyotype, the IDH1 Gly105Gly variant remained independently associated with shorter RFS (HR 3.97, 95% CI: 1.74–9.05, p = 0.001). Complex karyotype was also an independent predictor of relapse (HR 3.35, 95% CI: 1.28–8.73, p = 0.014). Consistent with this, logistic regression revealed a significantly increased odds of post-SCT relapse among cases (OR 7.95, 95% CI: 2.19–35.27, p=0.001), independent of clinical covariates. Relapsed cases were significantly more likely to harbor FLT3-ITD mutations than relapsed controls (p=0.041). Pathway-level analysis revealed increased frequency of mutations in signal transduction genes (FLT3-ITD, CSF3R, NF1) (p=0.002). All CNS relapses among cases occurred in patients harboring at least one of these mutations. Despite the higher relapse rate, there were no significant differences in OS (14.4 vs. 11.3 months, p=0.36) between cases and controls. The IDH1 Gly105Gly variant was not independently associated with OS (HR 1.26, p=0.30). In contrast, age (p<0.0001) and adverse ELN risk (p<0.0001) were significant predictors of inferior OS. These findings suggest that the prognostic impact of IDH1 Gly105Gly is most pronounced in the post-SCT setting. Conclusion The synonymous IDH1 Gly105Gly variant (rs11554137) is an independent predictor of post-SCT relapse in AML, potentially mediated by co-occurring mutations in signal transduction pathways. Despite no observed impact on OS, likely due to effective salvage therapies, the variant's link to lower CR rates with low-intensity therapy and higher MRD burden suggests treatment intensity influences its clinical relevance. These findings support reevaluating the prognostic role of synonymous variants in AML and call for larger studies and mechanistic investigations into splicing, transcript stability, and translation.

Abstract Background: Disease relapse is a major cause of mortality post allogeneic hematopoietic stem cell transplantion (alloHCT) in patients with myeloid neoplasms (MN). Cytogenetic risk classification is a key prognostic factor in predicting relapse post-transplant. Next generation sequencing (NGS) offers added prognostic insight by identifying relapse-associated mutations. We assessed the impact of mutation type and burden on post-alloHCT relapse risk and relapse-free survival (RFS) in MN patients with non-adverse-risk cytogenetics. Methods: We retrospectively reviewed patients who underwent alloHCT at Mayo Clinic Rochester between 01/01/2018 - 10/01/2023. Eligible patients had MN with non-adverse-risk cytogenetics [Acute myeloid leukemia (AML) with non-adverse-risk cytogenetics per ELN 2022, myelodysplastic syndrome (MDS) with non-high/very high-risk cytogenetics per IPSS-R criteria, and myeloproliferative neoplasms (MPN) (excluding myelofibrosis), chronic myelomonocytic leukemia (CMML), or MDS/MPN overlap with non-complex and non-monosomal karyotypes]. The primary endpoint was 3-year cumulative incidence of relapse (CIR) post-alloHCT, analyzed via competing risk models. RFS was estimated via Kaplan-Meier method. Prognostic mutations were identified using univariate (UVA) and multivariate (MVA) Cox models. A decision tree was used to define mutation-based relapse risk groups. Results: Of 585 patients, 215 (37%) met inclusion criteria; 133 (62%) were male. Median age at diagnosis was 61 years (IQR 53-65.5). Diagnoses included AML (125, 58.1%), MDS (55, 25.6%), CMML (17, 7.9%), MDS/MPN (11, 5.1%), and MPN (7, 3.3%). Median follow-up post-alloHCT was 3.2 years (IQR 1.9-5.2). Donor sources were mostly matched unrelated donors (120; 55.8%), followed by matched related donors (72; 33.5%), haploidentical donors (15; 7%), mismatched unrelated donors (6; 2.8%), and cord blood transplants (2; 0.9%). Most patients reduced intensity/non-myeloablative conditioning (144, 67%), while others received myeloablative (71, 33%). Mutation frequencies were as follows: ASXL1 58 (27.0%), RUNX1 45 (20.9%), FLT3 41 (19.1%), SRSF2 41 (19.1%), DNMT3A 39 (18.1%), STAG2 22 (10.2%), SF3B1 18 (8.4%),BCOR 18 (8.4%), WT1 16 (7.4%), U2AF1 13 (6.0%), ZRSR2 10 (4.7%), TP53 6 (2.8%), EZH2 3 (1.4%). In UVA, mutations in FLT3 (HR 2.15, p=0.018), SF3B1 (SF3B1 HR 3.08, p=0.002), PTPN11(HR 2.93, p=0.032), and WT1 (HR 2.29, p=0.069) were associated with increased risk of 3-year CIR. However, only FLT3 (HR 1.98, p=0.042) and SF3B1 (HR 4.0, p<0.001) retained significance in MVA. SF3B1 correlated with inferior 3-year RFS in UVA (HR 1.99, p=0.034) but not in MVA. Mutations in ASXL1, BCOR, EZH2, RUNX1, SRSF2, STAG2, ZRSR2, U2AF1, and TP53 had no significant impact on CIR or RFS. Harboring ≥2 or ≥3 mutations did not impact CIR or RFS. A decision tree model based on SF3B1, FLT3, DNMT3A, and WT1 mutations stratified patients into 3 risk groups. The high-risk group (n=32; 15%) had 50% 3-year relapse incidence (RI) and included patients with SF3B1 mutations or SF3B1-wildtype (WT) with concurrent FLT3 and DNMT3A mutations. The intermediate-risk group (n=36; 17%) included SF3B1-WT patients with either FLT3 mutations and DNMT3A WT (21% RI), or SF3B-1-WT and FLT3-WT patients with WT1 mutations (33% RI). The low-risk group (n=147; 67%) lacked all 4 mutations and had the lowest 3-year RI of 14%. The 3-year CIR significantly differed across these 3 risk groups (51.9%, 27.3%, and 15.8% in high, intermediate, and low-risk groups respectively; p<0.001). The 3-year RFS was significantly inferior in the high-risk group (35.55%, p=0.001), but similar among intermediate and low-risk groups (67.11% and 63.4%, respectively). Conclusion: In non-adverse risk cytogenetic MN, SF3B1 and FLT3 mutations predicted relapse post-alloHCT. Notably, mutations that were traditionally associated with adverse-risk AML per ELN 2022 (e.g, ASXL1, TP53) were not associated with relapse in this cohort. The discrepancy may reflect exclusion of patients with high-risk cytogenetics, as the prognostic impact of these mutations may depend on co-cytogenetic anomalies. In non-adverse-risk cytogenetics MN, we identified 3 groups of patients based on the presence or absence of SF3B1, FLT3, DNMT3A, and WT1 mutations. Those with mutated SF3B1 or concurrent FLT3/DNMT3A mutations experienced the highest risk of relapse post-alloHCT, translating into inferior RFS. Our findings need to be verified in a larger data registry.

Abstract Introduction: DDX41 (DEAD-box helicase 41) mutations (mt) represent the most prevalent germline predisposition syndrome (GPS) in adult patients (pts) with myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). This molecular subtype is typically associated with late-onset disease, runs an indolent clinical course, with a relative absence of high-risk co-mutations. While several retrospective studies have reported favorable responses to venetoclax (VEN)-based therapies, anecdotal observations suggest variable outcomes. We aimed to evaluate the clinical characteristics and treatment outcomes of patients with DDX41-mt MDS/AML treated at the Mayo Clinic. Methods: We conducted a retrospective study of pts diagnosed with DDX41-mt germline predisposition syndrome with concurrent myeloid neoplasms at our institution. Germline testing was conducted under an IRB approved protocol (Mayo Clinic IRB# 16-004173; clinical-trials gov. Identifier: NCT02958462). Of 198 pts with DDX41-mt myeloid neoplasms, 77 had high-risk disease—43 with MDS with increased blasts (MDS-IB1, n = 11; IB2, n = 32) and 34 with AML (WHO 2022). We assessed how clinical, and disease features influenced outcomes in this subgroup. Among these pts, 69 (90%) pts had likely pathogenic/pathogenic variant (DDX41path) variants and 8 (10%) pts had variant of undetermined significance (DDX41VUS) according to variant classification criteria from the American College of Medical Genetics/ the Association of Medical Genetics/ the Association for Molecular Pathology (ACMG/AMP) guidelines. Results: The median age was 68 years (yrs) (range [R],34-92), 70% were male and the median bone marrow blast % was 15 (R,5-60). The most common DDX41 germlinevariants (> 5% cases) included p.D140fs (26%), p.M1I (22%), and p.P258L (6.5%). 74% had DDX41 truncating variants. Thirty-one (40%) acquired a somatic DDX41-mt (R525H [81%]) and 43 (56%) had other somatic mutations. Among these, the most frequent were ASXL1 (n= 9, 21%), TP53 (n= 8, 10%), splicing factor (n= 7, 9%), and DNMT3A (n= 5, 6%). Twenty-six, (34%), 26 (34%), 15 (19%) and 9 (12%) pts were treated with hypomethylating agents (HMA), HMA+VEN, intensive chemotherapy (IC) and active surveillance/supportive care, respectively. Overall, the composite complete remission rate (cCR) in high-risk MDS and AML was 56%. The cCR rates (41%, 59% and 68.7%, p= 0.10) and median duration of response (DOR; 43.7, 44.9 and 28.9 months [mo], p= 0.46) were not significantly different with HMA, HMA+VEN, and IC induction. Thirty-one (40%) pts received allogeneic stem cell transplantation (allo-HCT); 4 (36%), 15 (47%) and 12 (35%) in MDS-IB1, MDS-IB2 and AML groups, respectively (p= 0.56). With a median follow up of 34.7 mo (R, 0.7-136.7), the median overall survival (OS) from the time of diagnosis was 56.9 mo (95% CI, 50.7-63.0) and was not significantly (NS) different between MDS-IB1 (not reached, 70% at 3 yrs), MDS-IB2 (56.9 mo, 86% at 3 yrs) and AML (55.7 mo, 60% at 3 yrs) groups, p= 0.16). The median OS was NS different between DDX41path and DDX41VUS (58.6 vs 55.7 mo, p= 0.50), respectively. We conducted a multivariable analysis for OS using variables that showed significance or trend towards significance in univariable analysis. Concurrent splicing factor mutations (HR; 5.29, 95% CI: 1.29-21.6, p= 0.02) remained negatively prognostic, while there was a trend towards better survival outcomes with allo-HCT (HR; 0.48, 95% CI: 0.21-1.07, p= 0.07). Bone marrow blast ≥ 20% (HR; 1.87, p= 0.12) and TP53-mt (HR; 2.14, p= 0.12) did not retain significance. Conclusion: In our cohort of patients with germline DDX41-mt high-risk MDS and AML, VEN-based regimens were not superior to HMA alone or IC, in terms of response rates and outcomes. On multivariable analysis, the presence of concurrent splicing factor mutations independently and negatively impacted survival with a trend towards better outcomes with allo-HCT. These findings highlight the heterogeneity within DDX41-mt myeloid neoplasms and underscore the need for future studies in larger cohorts to better define predictors of response and survival.