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Background: Systemic mastocytosis (SM) is a rare disease characterized by neoplastic mast cell (MC) infiltration of extracutaneous tissues. Nonadvanced SM (NonAdvSM) is associated with debilitating symptoms which may significantly reduce health-related quality of life (HRQoL). In up to 95% of patients (pts), SM is driven by the somatic KIT c.2447 A>T (p.D816V) missense mutation. Bezuclastinib (bezu; CGT9486) is an oral, potent, small molecule, selective type 1 tyrosine kinase inhibitor (TKI) with activity against KIT D816V. Results from Part 1 of the 3-part Summit trial demonstrated that bezu is well-tolerated and is associated with encouraging clinical activity, including both reduced MC burden and improvement in symptoms over a 12-week (wk) period vs placebo (PBO). Based on safety, PK, biomarker, and efficacy results, a dose of 100mg QD bezu (optimized formulation) was selected for Summit Part 2. Trial Design and Methods: Summit (NCT05186753) is a multi-center, Phase 2, double-blind, PBO-controlled RCT of bezu in pts with NonAdvSM who have inadequate control of symptoms despite treatment with best supportive care (BSC). A novel pt-reported outcome measure, the Mastocytosis Symptom Severity Daily Diary (MS2D2), was designed to assess disease-specific symptom severity in NonAdvSM pts. Eleven symptoms are included in the MS2D2 Total Symptom Score (TSS). Summit Part 1a randomized pts 1:1:1 to PBO, 100mg, or 200mg, original formulation while Part 1b randomized 1:1:1 to PBO, 100mg, or 150mg, optimized formulation. Pts completing Part 1 of the Summit trial were allowed to receive bezu in the open-label extension (OLE) Part 3 of the trial. Results: As Part 2 will evaluate safety and efficacy of 100 mg bezu at 24 wks, this abstract reports on pts treated with both bezu formulations at 100mg in Parts 1a or 1b, which had similar PK exposures. The presentation will focus on 24-wk outcomes in pts receiving the selected 100 mg bezu dose and participating in the OLE. In Summit Part 1, 19 pts received PBO and 18 received 100 mg bezu for 12 wks. At baseline (BL), the symptoms identified as most severe were within the skin and fatigue domains. At BL, pts were managing their symptoms of NonAdvSM with 2 (43%), 3 (24%), or ≥4 (32%) BSC medications. At the 12-wk assessment in Part 1 (datacut 18Dec2023), the safety and tolerability profile was encouraging, with the majority of TEAEs low grade and reversible without dose modification. The most common TEAEs (>10% in 100 mg bezu) included hair color changes, nausea, diarrhea, peripheral edema, GERD, taste disorder, and neutropenia. There were no reported bleeding or cognitive impairment events. Of 37 pts randomized to PBO or 100 mg QD bezu, 36 (97%) received bezu in the OLE; one pt randomized to the 100 mg original formulation dose reduced and subsequently discontinued due to TEAE of ALT increase. All 19 PBO pts (100%) crossed over to receive bezu in the OLE; of these, 9 were randomized to the 100mg QD bezu dose. Reduction in MC burden was robust among those treated with 100mg bezu - 94.4%, 100%, and 92.3% of pts had at least a 50% reduction in basal serum tryptase, KIT p.D816V variant allele frequency, and bone marrow MCs, respectively. Pts treated with 100 mg bezu had reduction in MS2D2 TSS by 49.1% vs 21.1% with PBO. On a 0-10 scale, the most severe MS2D2 symptom mean change from BL was -3.03 from a BL mean of 7.6 with bezu vs -1.04 from a BL mean of 7.7 with PBO. Individual symptoms of the MS2D2 TSS, as well as others not in the TSS including diarrhea and brain fog, improved more with bezu than with PBO; mean change from BL ranged from -1.66 to -2.69 with bezu vs. a range of -0.52 to -1.58 with PBO. LS mean change from BL in quality of life (Mastocytosis (MC)-QoL, a disease-specific measure) was -22.05 in pts treated with 100mg bezu versus -10.71 in pts treated with PBO. Objective measurements of skin lesions, including centrally adjudicated longitudinal assessments of skin photography, also significantly reduced on bezu. Conclusions: In Part 1 (12 wk assessment), treatment with 100mg bezu resulted in favorable safety and tolerability, significant and deep reductions across all markers of MC burden, and clinically meaningful reduction in all individual MS2D2 TSS symptoms and across domains. The presentation will report on durability and safety/tolerability data beyond 12 wks for those pts randomized to 100 mg in Part 1 and pts who crossed over from PBO in Part 1 to 100mg in Part 3. Summit Part 2 is actively enrolling.

Introduction: GOLCA is a potential first-in-class CELMoDTM agent for the treatment of lymphoma, purposefully designed to target the proteins Ikaros/Aiolos to produce dual immunomodulatory and anti-tumor activity, with preferential distribution to lymphoid organs. Pharmacodynamic data in pts with R/R FL show that, combined with RTX, the immunomodulatory effects of GOLCA are significantly increased (Chavez et al, EHA 2024, #1132). GOLCA as monotherapy (mono) and + RTX has been shown to be well-tolerated and effective in pts with R/R DLBCL (Chavez et al, ASH 2023, #4496) and R/R FL (Chavez et al, EHA 2024, #1132). Here, we report 30 mo follow up of pts with R/R FL who received GOLCA mono, and updated safety/efficacy of GOLCA + RTX from the ongoing Phase 1/2 CC-99282-NHL-001 study (NCT03930953). Methods: Pts with R/R FL with ≥ 2 prior lines of therapy (L) received GOLCA mono at different dosing schedules during part A (dose exploration) and GOLCA ± RTX at 0.2 mg or 0.4 mg days (d) 1-14 every 28 d (q28d) in part B (dose expansion). Total treatment duration with GOLCA was up to 2 years or until progressive disease or unacceptable toxicity, whichever occurred first. The efficacy-evaluable population consisted of pts completing ≥ 1 cycle of GOLCA and having baseline tumor assessment and ≥ 1 post-baseline tumor assessment or clinical progression or disease-related death. Results: As of May 31, 2024, 63 pts with R/R FL have enrolled: GOLCA mono (n = 19) at various dosing schedules and GOLCA + RTX at 0.2 mg (n = 22) or 0.4 mg (n = 22) on d1-14 q28d schedule. The median time from diagnosis to first dose of GOLCA was 68 mo (range, 23-136) and 59 mo (range, 15-309) in GOLCA mono and + RTX cohorts, respectively. The median number of prior therapies received was 4 (range, 2-11), and 3 (range, 1-12) in GOLCA mono and + RTX cohorts, respectively. In the GOLCA mono and + RTX cohorts, 9/19 (47%) and 13/43 (30%) pts had received prior lenalidomide (len)-based therapy, with 5/9 and 7/13 having len-refractory disease, respectively. In the GOLCA + RTX cohort, 10/43 (23%) had prior CAR T cell therapy and 6/43 (14%) had prior anti-CD20xCD3 bispecific antibody with or without CAR T cell therapy. In the GOLCA + RTX-treated safety population (n = 43), the incidence of treatment emergent adverse events (TEAEs) was similar across 0.2 and 0.4 mg dose levels (DL). The most frequent grade (G) 3+ TEAEs were neutropenia (44%) and anemia (12%). The incidence of febrile neutropenia was 7%. Serious adverse events occurred in 30% of pts, with febrile neutropenia and pneumonia being the most common, in 2 pts (5%) each, as well as pulmonary embolism in 1 pt. Neutropenia led to GOLCA dose interruption in 4 pts (9%) and dose reduction in 1 pt (2%). No pts discontinued treatment because of GOLCA-related TEAEs. Non-hematological TEAEs (e.g., GI toxicity, rash, fatigue) were all low-grade (except 1 pt with G3 fatigue). There were no new safety signals identified for GOLCA mono (part A) at the 30-mo follow up period. In the efficacy-evaluable population, at a median follow up of 6 mo (range 3-18), the ORR and CRR in the GOLCA + RTX cohort (n = 29) were 57% and 29% at 0.2 mg dose (n = 14) and 93% and 67% at 0.4 mg dose (n = 15), respectively. The median time to response was 2 mo (first response assessment). At the 0.4 mg DL of GOLCA + RTX, consistent responses were seen in pts at 2L/3L and 4L+, including in those with prior exposure to len-based therapies and/or T-cell-redirecting therapy. At the 0.4 mg DL, 12/14 (86%) pts remained in response at the time of data cut-off. In pts receiving GOLCA mono across different dose schedules in part A (n = 12), ORR and CRR were 67% and 42%, respectively. Responses were durable, with median DOR of 22 mo (range, 2-51) at a median follow up of 30 mo. 33% of pts (4/12) have completed 2 yrs of protocol defined GOLCA treatment and remain in response at the 1 yr post-treatment follow-up period, without requiring any intervening treatment. Conclusions: GOLCA 0.4 mg + RTX was well tolerated and highly active in heavily pre-treated pts with R/R FL, including those with prior exposure to len-based therapies and/or T-cell-redirecting therapies. Treatment with fixed-duration GOLCA mono led to durable responses including a subset of pts remaining treatment free, without progression at extended follow up. These data further support development of GOLCA + RTX as a fixed-duration, chemotherapy-free, outpatient treatment option in pts with R/R FL, and also pts with newly diagnosed advanced stage FL (NCT06425302).

Background: TP53-mutated (TP53mut) myeloid neoplasms (MN) have particularly poor survival. Discrepancies in defining TP53mut MN have impact on diagnostic work up, therapeutic decisions, and clinical trial enrolment. Methods: MN cases harboring TP53mut (variant allele frequency, VAF ≥2%) were classified based on bone marrow (BM) and peripheral blood (PB) blast % using the 4th revision of the WHO classification (WHO-4R). Biallelic loss was defined as (i) ≥2 mutations each with VAF ≥2%; (ii) single TP53mut VAF ≥2% plus 17p loss detected on karyotype, FISH, or SNP; or (iii) single TP53mut VAF ≥50%, whereas monoallelic loss was defined as single TP53mut VAF <50% without 17p loss. Primary endpoint was overall survival (OS) from diagnosis. Conditional Inference Trees (CIT) analysis was used to determine the true effect of a predictor. Results: We identified 580 cases including WHO-4R defined acute myeloid leukemia (AML, BM/PB blasts ≥20%, n=219, 37.8%), myelodysplastic syndrome (MDS) with excess blasts-2 (EB-2, BM 10-19% or PB 5%-19%, n=92, 15.9%), MDS with excess blasts-1 (EB-1, BM 5-9% or PB 2-4%, n=75, 12.9%), and the remaining were MDS with low blasts (-LB, BM <5% and PB ≤1%, n=194, 33.4%). Of the 578 cases evaluable for allelic status, 437 (75.6%) and 141 (24.4%) had biallelic and monoallelic TP53 loss, respectively. Higher frequency of biallelic loss was observed with increasing blasts. 63.2%, 73.3%, 78% and 86.3% of cases with MDS-LB, MDS-EB1, MDS-EB2, and AML had bi-allelic TP53 loss (P<0.0001). In a multivariable analysis, WHO-4R categories, VAF ≥10%, and biallelic loss were independent predictors of poor survival. CIT analysis further stratified the cohort into 4 groups with distinct survival: (1) MDS-LB (n=194, 33.4%); (2) MDS-EB1/EB2 and AML with VAF <10% (n=38, 6.6%); (3) MDS-EB1/EB2 with VAF ≥10% (n=149, 25.7%); and (4) AML with VAF ≥10% (n=199, 34.3%). MDS-LB cases could be further stratified based on allelic status and complex karyotype (CK): OS was poor for cases with biallelic TP53 loss and monoallelic TP53mut with CK compared to monoallelic TP53mut without CK, who had the most favorable survival (12.7 vs. 13 vs. 34.8 months, P<0.0001).MDS-EB1/EB2/AML with VAF<10% could also be stratified by CK: MDS-EB1/EB2/AML with VAF<10% cases without CK had the favorable survival compared to their counterparts with CK and MDS-EB1/EB2 with VAF ≥10% cases (26.2 vs. 5.6 vs. 6.3 months, P=0.003).MDS-EB1/EB2 with VAF ≥10% was a homogenous subgroup: Biological characteristics including the proportion of cases with biallelic TP53 loss, CK (P>0.9), monosomal karyotype (MK, P>0.9), del 5q (P=0.6), del 7q (P=0.4), and del 17p (P=0.2) were comparable between MDS-EB1 and -EB2 with VAF ≥10%. Importantly, median OS of MDS-EB1 and EB2 with VAF ≥10% was comparable (9.6 vs. 7.2 months, P=0.12). OS in this group was comparable regardless of the blast %, allelic status, or presence of CK.AML with VAF ≥10% had extremely poor survival: Median OS was 3.9 months. Survival of AML was equally poor irrespective of the mono- or biallelic (3.6 vs. 3.9, P=0.89) and non-CK vs. CK (1.8 vs. 3.9 months, P=0.09). Combined, our model would acknowledge poor survival of 514 (89.1%) cases. In contrast, retrospective application of the 5th edition of the WHO classification (WHO-5) and International Consensus Classification (ICC) would classify only 211 (36.4%) and 468 (80.7%) cases as biallelic/multi-hit TP53mut MN, respectively. Finally, the Harrell's c-index of the proposed model, WHO-5, and ICC was 0.66, 0.571, and 0.617, respectively. Conclusion: We provide evidence for subsequent refinements in classifying MN harboring TP53mut. Our salient findings include: (i) acknowledgement of CK as ‘biallelic equivalent’ in MDS-LB; as well as EB1/EB2/AML with VAF 2 to <10% cases; and (ii) demonstration of poor survival of MDS-EB1 and -EB2 with VAF ≥10% regardless of the allelic status. In conclusion, our proposed model acknowledged poor survival of a higher proportion of cases as TP53mut MN compared to the current models with a higher c- index.

Background Venetoclax + hypomethylating agent (Ven-HMA) therapy results in favorable response rates (CR/CRi 66%) and overall survival (OS; median 14.7 months) in unfit patients with newly-diagnosed acute myeloid leukemia (ND-AML; N Engl J Med 2020;383). However, there is substantial heterogeneity in individual patient outcomes based on response to treatment. The objective of the current study was to develop a genetic risk model to predict survival outcome in treatment responders and non-responders, analyzed separately, and also account for allogeneic stem cell transplant (ASCT). Methods Treatment-naïve AML patients receiving Ven-HMA, outside of a clinical trial, at the Mayo Clinic, USA (MN, AZ, FL) were retrospectively recruited. Molecular studies (48-gene panel) were performed by next-generation sequencing. Response was assessed according to the 2022 European LeukemiaNet (ELN) criteria (Blood 2022;140). Standard statistical analyses were performed using JMP Pro (Version 17.0.0). Results 400 ND-AML patients (median age 73 years, 64% male, 60% de novo) received Ven-HMA. ELN cytogenetic risk included favorable 2%, intermediate 60%, or adverse 38%. Mutations involved TP53 in 26%, TET2 19%, RUNX1 19%, SRSF2 18%, ASXL1 18%, DNMT3A 15%, K/NRAS 13%, NPM1 12%, IDH2 12%, FLT3-ITD 10%, IDH1 7% and DDX41 in 4% of informative cases. 153 (38%) patients achieved CR, 94 (24%) CR with incomplete count recovery (CRi), resulting in CR/CRi in 247 (62%) patients. CR/CRi rates were higher with NPM1 (86% vs 59%), IDH2 (77% vs 60%), and DDX41 mutations (93% vs 61%) and lower with TP53 (45% vs 67%), FLT3-ITD (41% vs 64%), RUNX1 (49% vs 65%) mutations and adverse karyotype (48% vs 71%), with all retaining significance in multivariable analysis. CR/CRi rate was highest (87%) in 75 patients with one or more favorable mutations (NPM1, IDH2, DDX41) and no unfavorable mutation (TP53, FLT3-ITD, RUNX1). CR/CRi rate was lowest in 171 patients with at least one unfavorable mutation and no favorable mutation (44%; p<0.01). After a median follow up of 10.5 months (0.5-66), 105 relapses (43% of patients in CR/CRi), 248 (62%) deaths and 65 (16%) ASCT were documented. Univariate analysis for transplant-censored OS disclosed superior survival in patients achieving CR/CRi (median 21 vs 3.6 months; HR 5.4, 95% CI 4.1-7.1). Among patients achieving CR/CRi, IDH2 mutation was associated with superior (median not reached vs 20.5 months) and male gender (median 17.6 vs 29.2 months), TP53 mutations (median 11.9 vs 24.3 months) and adverse karyotype (median 12.6 vs 29.4 months) with inferior survival; multivariable analysis resulted in HRs (95% CI) of 2.1 (1.3-3.4) for male gender, 2.1 (1.2-3.8) for adverse karyotype, and 2.5 (1.1-5.7) for absence of IDH2 mutations. Male gender did not show an association with karyotype, or TP53 mutations (p>0.1). Accordingly, an HR-weighted genetic risk model was generated with assignment of one point each to male gender, adverse karyotype, and absence of IDH2 mutation: high risk = 3 risk factors (n=38; median 9.6 months; 3-year survival 0%); intermediate risk = 2 risk factors (n=129; median 22 months; 3-year survival 38%); and low-risk = ≤1 risk factor (n=78; median not reached; 3-year survival 69%; p<0.01). In patients bridged to ASCT (n=60), post-transplant survival was inferior in the presence of ≥ 2 risk factors (n=42; median 46 months) vs. ≤1 risk factor (n=18; median not reached; p=0.1). In patients not achieving CR/CRi, risk factors for OS included male gender (median 3.4 vs 6.1 months), adverse karyotype (median 3.3 vs 4.5 months) and TP53 mutation (median 3.1 vs 4.5 months) while those with IDH2 mutations lived longer (median 8.4 vs 3.4 months). In multivariable analysis, HRs (95% CI) were 1.9 (1.3-2.9) for male gender, 2.0 (1.4-2.9) for adverse karyotype, and 2.1 (1.1-4.3) for absence of IDH2 mutations. OS was shortest for non-responders harboring 3 risk factors (n=45; median 3 months; 1-year survival 0%) and longer for those harboring two (n=80; median 6 months, 1-year OS 15%) or ≤ 1 risk factor (n=25; median 14 months; 1-year OS 56%; p<0.01). Conclusion The current study describes a molecular profile for predicting response to Ven-HMA in ND-AML and also introduces a novel approach to survival prediction that considers treatment response as the starting point. In both responders and non-responders, male gender and adverse karyotype were identified as unfavorable and IDH2 mutation favorable risk factor for OS.

Background: Philadelphia (Ph)-like acute lymphoblastic leukemia (ALL) is a heterogenous subtype of B-ALL defined by the presence of gene expression profiling similar to Ph+ ALL in the absence of a BCR::ABL1 fusion. Ph-like ALL has lower response rates to standard frontline therapies and carries a poorer prognosis when compared to other B-ALL subtypes. However, the role in which specific patient characteristics may impact responses is not well described. Our aim for this retrospective study was to evaluate the characteristics and outcomes of a real-world cohort of patients (pts) with Ph-like ALL across multiple institutions, including describing key patient characteristics, treatments, and factors that may contribute to minimal residual disease (MRD) status and treatment response. Methods: We conducted a retrospective review of adult pts with Ph-like ALL diagnosed and treated at the University of New Mexico, Mayo Clinic Phoenix, University of Chicago, and University of Michigan between 1/1/18 - 2/1/2024. Pts were eligible if they carried a diagnosis of B-ALL, and were determined to have Ph-like ALL according to each institutional diagnostic algorithm. Descriptive statistics, ANOVA, and Fisher's exact test were employed to summarize various clinical characteristics and their associations. Cox regression analysis was utilized to estimate the median survival time and assess the relationship between clinical characteristics and survival outcomes, including overall survival and progression-free survival. All statistical analyses were conducted using the R statistical software. Results: 67 pts were identified with a median age of 34.2 (IQR 28.5) and 35.8% were female. Twenty-eight pts identified as Hispanic or Latino (H/L) (43.1%), 25 (38.5%) identified as non-Hispanic White/Caucasian (NHW), 10 (15.4%) as American Indian/Alaska Native (AI/AN), and 2 (3.1%) as Asian/Pacific Islander. Thirteen pts (19.4%) had central nervous system (CNS) involvement at diagnosis, 22.4% of pts had extramedullary disease, and, in those who had NGS or cytogenomic microarray testing (n=49), 51% had an identified mutation/deletion in IKZF1. Initial treatment varied widely with pts receiving most commonly: Children's Oncology Group (COG) protocols (22.4%), CALGB 10403 (22.4%), HyperCVAD (11.9%), and CALGB 8811 (10.4%). Fifty-eight percent achieved a CR/CRi and 21% were refractory to initial therapy. Thirteen percent of pts received a Jak inhibitor and 6% of pts were treated with a TKI. Thirty pts (50.8%) underwent allogeneic stem cell transplant, with 8 of those pts (26.7%) experiencing a relapse post-transplant. Nine pts (13.4%) underwent treatment with CAR-T therapy with few pts experiencing grade 2 or higher cytokine release syndrome (CRS) or immune effector cell-associated neurotoxicity syndrome (ICANS). Pts with CNS disease at diagnosis were less likely to achieve a CR/CRi compared to those without CNS disease at diagnosis (33.3% vs 64.0%; p=0.12). Pts identifying as AI/AN were more likely to be refractory to their first treatment compared to other racial/ethnic groups (75%, p=0.002). Forty two percent of pts never achieved MRD negativity (< 0.01% by flow cytometry) during treatment; pts identifying as H/L and AI/AN had a higher rate of MRD positivity after induction compared to NHW pts (56% and 70% vs. 25%; p=0.02). In pts with IKZF1 mutation, 57.1% did not achieve MRD negativity compared to 21.7% in pts without a mutation (p=0.029). The median overall survival (OS) was 66.3 months (mos) and the median progression-free survival (PFS) was 15.7 mos. Pts who did not achieve MRD negativity after initial treatment had shorter OS compared to those who did achieve MRD negativity, 33.9 mos vs 66.3 mos (p=0.086). Progression-free survival (PFS) was significantly shorter for patients who did not achieve MRD negativity after initial treatment compared to those who did, 3.9 mos vs 43.9 mos (p=0.001). PFS was shorter in pts who identify as AI/AN compared to H/L and NHW pts (2 mos vs 35.7 mos and 35.7 mos; p=0.046). Conclusion: Pts with Ph-like ALL experience poor response rates to therapies used to treat B-ALL, highlighting the urgent need for novel therapies and treatment strategies. We identified race/ethnicity and CNS disease at diagnosis as risk factors for poor treatment response. In addition, race/ethnicity and the presence of an IKZF1 mutation was associated with worse rates of MRD negativity during treatment.

Background Venetoclax + hypomethylating agent (Ven-HMA) therapy has demonstrated improved outcomes in elderly/unfit patients with newly-diagnosed acute myeloid leukemia (ND-AML) (N Engl J Med 2020;383). However, ~50% of patients who respond to Ven-HMA, eventually relapse (Am J Hematol 2024;99). In the current study we examined the prognostic contribution of gene mutations, karyotype, measurable residual disease (MRD) status and clinical risk factors for relapse in patients with ND-AML treated with Ven-HMA therapy. Methods Our study population of ND-AML was retrospectively recruited from Mayo Clinic (MN, AZ, FL), after institutional review board approval and based on documentation of complete remission with/without count recovery (CR/CRi) following Ven-HMA therapy. Relapse-free survival was determined from the time of remission to relapse or last follow-up. Survival analysis was censored for transplant. The 2022 European LeukemiaNet (ELN) criteria was used to assign cytogenetic risk and classify treatment response (Blood 2022;140). Standard statistical analyses were performed using JMP Pro (Version 17.0.0). Results 247 ND-AML patients treated with Ven-HMA (median age 73 years, 62% male, 64% de novo) who achieved CR (n=153), or CRi (n=94) were included. MRD by multiparameter flow cytometry (sensitivity 0.01%) performed at the time of CR/CRi, was negative in 117 (70%) of 166 informative cases. ELN cytogenetic risk categories at diagnosis included favorable 2%, intermediate 69%, or adverse 29%. Mutations involved TET2 21%, SRSF2 21%, TP53 19%, ASXL1 18%, DNMT3A 18%, NPM1 17%, IDH2 15%, RUNX1 15%, K/NRAS 12%, IDH1 8%, FLT3-ITD 7%, and DDX41 in 6% of informative cases. Relapse was documented in a total of 99 (40%) patients who achieved CR (39%) or CRi (41%) after a median remission duration of 6 months (1-31). Patients that relapsed within the first-year vs those that did not, were more likely to be males (75% vs 55%), MRD positive (44% vs 24%), and harbor TP53 mutations (23% vs 16%). Univariate analysis for RFS identified male gender (12 vs 29 months; p=0.02), secondary AML (10 vs 21 months; p<0.01), adverse karyotype (9 vs 22 months; p<0.01), TP53 mutations (6 vs 18 months, p<0.01) and MRD positive remission (13 months vs not reached; p<0.01) as risk factors for relapse; on the other hand, IDH2 mutations (not reached vs 15 months; p<0.01) were associated with a lower risk of relapse. Multivariable analysis confirmed male gender (HR 2.2), TP53 mutations (HR 3.0) and MRD positive remission (HR 1.7) as unfavorable predictors of relapse. Subsequently, in a three-tiered relapse prediction model, RFS was significantly inferior in the presence of three risk factors (male gender, TP53 mutations, MRD positive remission) (n=10, median 4 months), vs two (n=34, median 10 months) vs ≤ 1 risk factor (n=122, median 31 months) (p<0.01); 1-year cumulative incidence of relapse was 100%, 56%, and 26% in the presence of three, two and ≤ 1 risk factors, respectively. 50 of 99 (65%) patients received salvage therapy which included cladribine-cytarabine-Ven (n=19), intensive induction chemotherapy (n=9), FLT3 inhibitors (n=5), Ven-HMA-FLT3 inhibitor (n=1), IDH1/2 inhibitors (n=5), glasdegib-cytarabine (n=4), gemtuzumab (n=3), lenalidomide (n=1), or investigational therapies (n=3); in addition, Ven-HMA was resumed in 14 patients in whom treatment had been discontinued for a median of 5 months (2-12). Overall, 20 (31%) of patients achieved second CR/CRi and response rates were similar with intensive vs less intensive therapy (CR/CRi; 44% vs 29%; p=0.37). Median follow up after relapse was 3.4 months (1-66), during which 73 (74%) deaths, and 4 (5%) ASCT were recorded. Median transplant-censored survival was 4.2 months (1-year; 22%), and inferior in patients with adverse karyotype (median 4.6 vs 3.4 months; p=0.02), and TP53 mutations (3.6 vs 4.4; p=0.11); on the other hand, male gender (3.5 vs 6.8 months; p=0.51), MRD positive remission (4.6 vs 4.2; p=0.56), and IDH2 mutations (6.7 vs 4.2; p=0.28), did not influence post-relapse survival. Conclusions The current study identifies male gender, TP53 mutations, and MRD status as powerful predictors of relapse and proposes a relapse prediction model for ND-AML patients receiving Ven-HMA therapy. Furthermore, relapse following Ven-HMA was associated with uniformly poor outcomes, regardless of salvage treatment strategy.

Introduction: DDX41, DEAD-box RNA helicase 41 gene located on chromosome 5q25.3, is one of the most mutated genes in patients with germline predisposition to myeloid neoplasms. Germline and somatic mutations often have different locations and patterns of mutation, with some hot-spots displaying diversity based on ethnicity. We aimed to explore clinical outcomes in patients with various DDX41 hot-spots. Methods: A retrospective study of patients at Mayo Clinic with DDX41 mutation identified through Next Generation Sequencing (NGS) between 2016 and 2024. Patients classified as germline DDX41 variants or somatic variants based on confirmed germline testing results. Data regarding mutations recorded at time of patients' first in-house NGS. We completed unadjusted comparisons using continuous or categorical variables, and survival rates assessed using Kaplan-Meier method and cox regression analysis. Median overall survival calculated from time of NGS to last follow-up or death using BlueSky Statistics V.10.3.4 Results: Clinical Characteristics: Eighty-two patients analyzed, predominantly male (69.5%), with median age of diagnosis of 68 years (IQR 62-75). Most common diagnosis was MDS (50%), followed by AML (22%) and myeloproliferative neoplasm (MPN) (7.3%). Fourteen percent were DDX41 mutation carriers, 4.9% clonal cytopenia of undetermined significance (CCUS), and 1.2% chronic neutrophilic leukemia (CNL). MDS-IB2 was the prevalent MDS subtype (56.1%), and 83.3% of AML patients were intermediate risk. Cytogenetics normal in 73.8% of patients, with del20 being the most common abnormality (7.5%). Twenty-five (30.5%) of patients underwent allogeneic hematopoietic cell transplantation (alloHCT). Forty-nine patients (59.8%) had pathogenic DDX41 mutation only, 15 (18.3%) had only VUS, and 18 (22.0%) had both. Molecular Characteristic s: Mutation hot-spots included 12.2% with p.Arg525His only, 28% p.M1I only, 9.8% p.Asp140GlyFs*2 only, 9.8% p.Arg525 with co-mutation other than p.M1I/p.Asp140. Two patients (2.4%) had p.M1I co-mutation with non-p.Arg525 and p.Asp140, while 1 patient (1.2%) had p.M1I and p.Arg525, and 1 patient (1.2%) had p.Asp140 and p.Arg525. Lastly, 33 patients (40.2%) had mutations in hot-spots other than specified in this study. Median hemoglobin (Hg) was lowest in patients with p.Arg525 hotspot mutation (9.9 g/dl), compared to median Hg of 11.2 g/dl in group with p.M1I and 10.4 g/dl in p.Asp140 only group (p=0.87). The most common cytogenetics in patients with only p.Arg525 and only p.M1I hot-spot mutation was normal cytogenetics (70% and 90.9%, p=0.5). In the 16 patients with proven germline DDX41 mutation, 7 (43.8%) had mutations in only p.M1I. Lastly, median (m) VAF was significantly lower in the group with only p.Arg525 hot-spot mutation (9.5%, IQR 5.5-13.8), compared to mVAF of 48% in patients with only p.M1I (IQR 48.0-49.5, p<0.001). Co-mutations: The most frequent co-mutation was DNMT3A (11.0%), followed by JAK2 (9.8%).Mean number of co-mutations in p.Arg525 only was 0.6, 0.3 in p.M1I only, and 0.5 in p.Asp140 only (p=0.8). Most common co-mutation in p.M1I was ASXL1, with 13.0% of patients with p.M1I only having ASXL1 co-mutation (p=0.062). The most common co-mutation in p.Asp140 was DNMT3A (p=0.7). Survival: Median overall survival (mOS) was 21.5 months (IQR 12.4-38.6). mOS for p.Arg525 only group was 31.3, compared to 41.2 months in p.M1I only (p=0.197). At 12- and 24-months, survival rate was 88.9% and 59.3% in the p.Arg525 only group, compared to p.M1I group with 100% survival rate at 12 months and 89.5% at 24 months. p.Asp140 had 87.5% survival rate at both 12 months and 24 months. Males in p.M1I group had lower survival rate at 24 months (81.8%), compared to 100% survival in females. p.M1I only group with alloHCT also had lower 24 month survival at 60% compared to 100% in group who did not undergo alloHCT. Conclusions: The p.M1I hot-spot was commonly seen in patients with germline DDX41 mutation, likely resulting in significantly higher VAF percentage. Co-mutations frequency differed by hot spot mutation while p.Arg525 as second mutation was seen mainly in cases other than p.M1I/pArg140Gly. Overall survival appears to be higher in p.M1I/pArg140Gly compared to p.Arg525His hot-spot mutation, though males with p.M1I and those who underwent alloHCT had lower survival. Findings suggest implications for clinical outcomes based on DDX41 mutation hot-spots.

Introduction Symptom burden in myeloproliferative neoplasms (MPN) is quantified using total symptom scores (TSS) calculated from the patient-reported scores for clinically meaningful symptoms. The impact of demographic, clinical, and laboratory features on these symptoms remains unclear and warrants further investigation. Methods Patients with polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis (MF) were identified from the retrospective chart review. TSS, scores of individual symptoms (fatigue, early satiety, abdominal discomfort, inactivity, concentration difficulties, fever, night sweats, itching, bone pain, weight loss), demographic characteristics (race, ethnicity, age, and gender), clinical features (time since diagnosis, depression status, obesity status), laboratory results and season at the time of visit when the first TSS assessment was performed were recorded. Multicollinearity and homoscedasticity were assessed using variance inflation factors and visual inspection of the data, respectively. A multivariable regression analysis was performed using a robust variance estimator. A p-value <0.05 indicated a statistically significant association with the symptom scores. Results The chart review identified 557 (PV: 201; ET: 191; MF: 165) patients. The median age of patients with PV, ET, and MF was 65 (range: 27-93), 65 (20-96), and 69 (27-96) years, respectively. Most patients were white (PV: 92%; ET: 90%; MF: 93%) and non-Hispanic or Latino (PV: 93%; ET: 96%; MF: 92%). Most patients with PV and ET were female (PV: 51%; ET: 73%), while most patients with MF were male (55%). Among the included patients 22% (PV: 21%; ET: 27%; MF: 18%) had the diagnosis of depression at the time of the clinical visit. TSS was highest in MF (mean (SD): 18.1±14.6), followed by PV (15.7±14.5) and ET (15.1±14.0) patients. Fatigue was the most reported symptom by the patients (PV: 81%; ET: 82%; MF: 84%), whereas weight loss was the least reported symptom (PV: 4.5%; ET: 6.3%; MF: 16%). With regards to the TSS multivariable regression analysis showed that age (beta coefficient: 0.2; p=0.01), depression (7.2; 0.008), and low hemoglobin (1.2; 0.003) in PV, depression (11.7; 0.001) in ET, and depression (9.5; 0.001), splenomegaly (6.9; 0.01), and WBC count (0.16; 0.048) in MF patients were significantly associated with TSS. In terms of individual symptoms in PV, depression was associated with fatigue (beta coefficient: 1.31; p-value: 0.01) and concentration difficulties (1.7; <0.001), high WBC count was associated with early satiety (0.09; 0.03), and non-white race was associated with fever (1.4; 0.007). In ET, depression was associated with fatigue (1.6; <0.001), abdominal discomfort (1.4; <0.001), inactivity (2.5; <0.001), concentration difficulties (2.4; <0.001) and night sweats (1.4; <0.001), anemia was associated with fatigue (1.2; 0.03), fewer months since diagnosis was associated with inactivity (0.01; 0.02) and young age was associated with bone pain (0.02; 0.03). In MF, depression was associated with fatigue (1.8; 0.001), concentration difficulties (1.3; 0.01), fever (1.1; 0.02), and night sweats (2.2; 0.03), low hemoglobin was associated with fatigue (0.46; <0,001) and early satiety (0.31; 0.003), high WBC count was associated with fatigue (0.03; 0.04) and early satiety (0.04; 0.02), low platelet count was associated with abdominal discomfort (0.002; 0.03), splenomegaly was associated with inactivity (2.27; 0.003) and female gender was associated with itching (0.57; 0.01). Conclusions This study demonstrates that depression in PV and ET and depression, low hemoglobin, and a high WBC count in MF contribute to multiple symptoms seen in these patients. Identifying demographic groups at risk of a higher symptom burden and addressing the comorbidities that drive symptoms, in addition to disease-directed therapy, is crucial to improving the quality of life in these patients.

Background TP53-mutant (mt) myelodysplastic syndromes (MDS) are high-risk (HR) neoplasms, with high rates of AML progression and suboptimal response to hypomethylating agents (HMA). Given the lack of effective therapies for HR-MDS, azacitidine (AZA) was combined with venetoclax (VEN) in a phase Ib MDS study demonstrating safety and early efficacy (Garcia et al. ASH abstract 2023). We retrospectively sought to explore clinical outcomes comparing VEN + HMA, to HMA alone in TP53mt HR-MDS. Methods Among 221 TP53mt MDS pts treated at the Mayo Clinic between January 2007 and April 2024, we reviewed outcomes of pts who received HMA alone (n=98) or HMA+VEN combination (n=34) as their first-line chemotherapy regimen. MDS diagnosis was based on the 5th edition of WHO classification of hematolymphoid tumors (Khoury et al. Leukemia 2022). Responses were assessed according to the International Working Group 2006, MDS response criteria (Cheson et al Blood 2006). Results Baseline characteristics and response The median age (years [yrs]) was 65 (R,37-80) and 70 (range [R], 19-87) yrs in the HMA + VEN and HMA alone groups (gps) (p= 0.42), respectively. The median bone marrow (BM) blast % (9.5 [R, 0-18] vs 5 [R, 0-16], p= 0.01) and TP53 variant allele frequency (VAF) (42 [R, 6-96] vs 37 [R, 2-94], p= 0.03) were significantly higher in HMA + VEN compared to HMA gps, respectively. However, proportion of pts with biallelic (BA)/multihitTP53mt (85% vs 79%, p= 0.61) and complex cytogenetics (CG) (85% vs 81%, p= 0.85) were not different between HMA + VEN and HMA alone gps. The distribution of pts with frequently occurring myeloid co-mutations (ASXL1, TET2, DNMT3A, RAS, BCOR and splicing factor) were not significantly (NS) different between the two gps. IPSS-M scores were assessed in 108 (83%) pts; HR/very HR-MDS as per IPSS-M were NS different between HMA + VEN and HMA gps (100% vs 91%, p= 0.12). While the overall response rate (ORR) (76% vs 49%, p= 0.01) and marrow complete remission (mCR) rates (21% vs 7%, p= 0.05) were higher with HMA+VEN compared to HMA, CR rates were similar (17% vs 12%, p= 0.47). Higher proportion of pts were bridged to allogeneic stem cell transplantation (allo-HCT) (41% vs 20%, p= 0.02), while AML progression rates (29% vs 31%, p= >0.99) were comparable between HMA + VEN and HMA gps, respectively. The non-relapse mortality (NRM) at day 60 (3% vs 3%, p=0.96) and day 90 (3% vs 4%, p=0.75) were comparable between HMA + VEN and HMA gps, respectively. RFS and OS The median follow-up from the time of initiation of HMA or HMA + VEN was 9.7 months (mo) (R, 0.3-90.6). The median RFS (8.47 vs 9.90 mo, p= 0.83) and OS (16.33 vs 14.20 mo, p= 0.66) from the time of initiation of therapy were comparable between the two gps. Similarly, among transplanted pts, there was no OS difference between HMA (21.7 mo) and HMA + VEN (18.43 mo) gps, respectively (p= 0.72). Comparable results for OS and RFS were obtained in both gps after censoring pts at the time of allo-HCT. Multivariable analysis for RFS and OS We conducted multivariable analysis (MVA) for RFS and OS using baseline variables that were significant/ trended towards significance (p<0.1), on univariate analysis (UVA) censored at the time of allo-HCT. Achieving ORR (HR; 0.30, 95% CI: 0.14-0.62, p= 0.001) retained significance for better RFS in MVA. Interestingly CR (HR; 1.74, 95% CI; 0.63-4.77, p= 0.28), BA TP53mt (HR; 1.27, 95% CI; 0.13-11.72, p= 0.83) and complex CG (HR; 1.52, 95% CI 0.16-14.03, p= 0.70) did not retain significance for RFS in MVA. In MVA for OS, achievement of ORR (HR; 0.56, 95% CI; 0.30-1.05, p=0.07) and CR (HR; 0.32, 95% CI; 0.09-1.11, p=0.071) trended towards favorable OS. BA TP53mt status (p= 0.42) and complex CG (p= 0.19) did not significantly impact OS in UVA. Conclusion We conclude that while HMA+VEN combination therapy in comparison to HMA monotherapy led to improved response rates, with higher percentage of pts being bridged to allo-HCT, this was not associated with reduced risk of AML transformation, or improved RFS/OS. We eagerly await results from the prospective randomized trial of VEN + AZA in treatment-naïve HR-MDS (VERONA).

Background: Clonal cytopenia of undetermined significance (CCUS), a precursor of myeloid neoplasms (MN), is characterized by one or more persistent cytopenias, and acquired mutations in myeloid malignancy-associated genes. ZRSR2, located at Xp22.2, is one of the MN-associated genes and a member of the spliceosome family of genes. Aim: Describe the clinical characteristics, pattern of progression, and genetics of ZRSR2 mutation (ZRSR2m)-harboring CCUS patients. Methods: Next-generation sequencing (NGS) was performed for 9320 patients between 2016-2023 at Mayo Clinic. After obtaining IRB approval, clinical characteristics and results of bone marrow morphology, cytogenetics, and molecular studies were abstracted. Overall Survival (OS) was calculated using Kaplan-Meier, from the date of NGS until death or last follow-up. The ZRSR2m MN control cohort included 125 patients with myelodysplastic syndrome (MDS), myeloproliferative neoplasm (MPN), and MDS/MPN overlap. BlueSky Statistics V10.3.1 was used for statistical analysis. Results: ZRSR2m was detected in 39 CCUS patients, all of whom were males. Concurrent hematological neoplasms were identified in 8 patients (21%). Five (13%) had plasma cell proliferative disorders including 3 multiple myeloma, 1 MGUS, and 1 AL amyloidosis. There were also 2 patients with chronic lymphocytic leukemia and 1 with VEXAS syndrome. Prior chemotherapy, with or without radiotherapy, was given to 4 patients (10.3%), whereas 13 patients (33%) had received previous immunotherapy. Abnormal cytogenetics were detected in 11 patients (29%), with the most common abnormality being +8 (n=5, 13%). In 23 patients (59%), an absolute monocyte count of ≥0.5 x 10^9/L was documented which could be classified as clonal cytopenia with monocytosis of unknown significance (CCMUS). ZRSR2 median gender-corrected VAF among CCUS patients was 32% (range, 1-45). Isolated ZRSR2m was found in 6 patients (15%), and 1 (3%) had multiple ZRSR2m. The median number of co-mutations was 1 (range, 0-3). Sequential NGS, available in 13 patients, showed that 1 patient developed 3 ZRSR2 mutations and 2 ZRSR2 VUS. TET2 was the most common co-mutation (n=25, 64%). Additionally, TET2 was an isolated co-mutation in 18 patients (46%). ASXL1 co-mutation was the second most common (n=8, 20.5%), while other less common co-mutations were IDH1, IDH2, SRSF2, SF3B1, TP53, GATA2, and KDM6A. Pre-ZF1 was the most commonly mutated region in ZRSR2 mutations (n=23, 59%). With a median follow-up of 32 months, 9 (23%) of the ZRSR2m CCUS patients progressed to MNs, none progressed to AML. Five (55.6%) progressed to MDS, 4 were subclassified as low blast (LB) and 1 as increased blast-1 (IB1). Four (44.4%) progressed to MDS/MPN overlap syndrome, with 3 subclassified as chronic myelomonocytic leukemia (CMML). None of the patients with isolated ZRSR2m progressed to MDS or CMML. None of the patients who received prior immunotherapy progressed to MDS. Thirty-six (92.3%) patients had high-risk CCUS (Malcovati et al, Blood 2017) while 3 had intermediate risk with no low-risk patients. None of the intermediate-risk patients progressed to MDS, while 5 patients of the high-risk (13.9%) progressed to MDS (p=1). Twelve (31%) patients died, and the median overall survival (mOS) was 56 months. Higher hemoglobin levels improved OS (HR=0.59, p=0.02), while higher adjusted ZRSR2 VAF worsened OS (HR=1.05, p=0.017). Patients with TET2 as isolated co-mutations showed better mOS than the rest of the cohort (not reached vs 41 months, p= 0.03). ZRSR2m CCUS patients showed a trend suggestive of better mOS than ZRSR2m with MNs including AML (56 vs 30 months, p=0.14), and with excluding AML (56 vs 39 months, p=0.24). On multivariate analysis, both Hgb (HR=0.61, p=0.03) and isolated TET2 co-mutation (HR=0.19, p=0.04) retained statistical significance. mOS was not affected by prior history of treatment, number of co-mutations, isolated ZRSR2, ASXL1 co-mutation, or MDS progression. Conclusion: ZRSR2m CCUS cohort was exclusively males. There was a significant number of patients with concurrent hematological malignancy or a history of prior chemo- and/or immuno-therapy (36%). Most patients had high-risk CCUS but showed a low rate of progression to MNs, especially in those with isolated ZRSR2. Additionally, patients with isolated TET2 co-mutation had better survival, indicating that TET2 confers a favorable prognosis among ZRSR2m CCUS patients.