Nanaa, Ahmad

Background/Objectives: 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 hotspots displaying diversity based on ethnicity. We aimed to explore clinical outcomes in patients with various DDX41 hot-spot mutations. Methods: This was a retrospective study of patients at Mayo Clinic with DDX41 mutation identified through Next Generation Sequencing (NGS) between 2018 and 2024. We completed unadjusted comparisons using continuous or categorical variables, and survival rates were assessed using the Kaplan–Meier method and cox regression analysis. Results: Overall survival appears to be higher in those with p.M1| when compared to p.Asp140GlyFs*2 and p.Arg525His, with comparable survival between p.Arg525His and p.Asp140GlyFs*2. Among males with p.M1| who underwent bone marrow transplant, those who underwent bone marrow transplant appeared to have lower survival rates, although not statistically significant. Our study was limited by a small sample size, therefore limiting our ability to reach significance. Conclusions: Our findings suggest potential implications for clinical outcomes based on DDX41 mutation hot-spots.

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.

Background: Clonal cytopenia of undetermined significance (CCUS) is characterized by the presence of a clone with somatic mutations in genes associated with myeloid neoplasms (MN) or abnormal cytogenetics, along with unexplained and persistent cytopenias in the absence of significant marrow dysplasia. CCUS is considered a premalignant state with a risk of progression to MN. The clinical outcomes of patients (pts) with high risk CCUS (Weeks et al, NEJM Evidence 2023) may be similar that of some patients with myelodysplastic syndromes (MDS). This study aims to predict the outcomes of CCUS patients using the molecular international prognostic scoring system (IPSS-M) developed for MDS. Methods: A retrospective analysis was conducted in patients diagnosed with CCUS between 2015 and 2023, we included patients harboring pathogenic mutations (MUT) identified through next-generation sequencing (NGS) testing at two institutions: Mayo Clinic and the University of Texas Southwestern Medical Center, Dallas, TX, USA were included. Progression was considered present if patients with CCUS progressed into myeloid neoplasm at follow up. Statistical analysis was performed using JMP® 17.1.0 Software. IPSS-M risk scores were calculated via the IPSS-M Risk Calculator (mds-risk-model.com). Results: A total of 103 patients were included in the study. The median age was 72 years, the majority were male patients (73%), and the median bone marrow blast % at the time of NGS was 1%. Forty-five % had an isolated mutation in a single gene, and 55% had co-mutations in ≥1 gene. The median number of mutations was 2 (range 1 - 5), occurring across 43 different genes. The most common mutations were in TET2 (N=28; 27%), ASXL1 (N=21; 20%), SRSF2 (N=21; 20%), U2AF1 (N=18; 17%), DNMT3A (N=16; 16%), and TP53 (N=12; 12%). Additionally, 25% of patients had an abnormal karyotype. Hematologic and genetic characteristics are summarized in (Table 1A). The median IPSS-M score was -0.9 (-3 to +2.34) and the median IPSS- Revised (R) score was 2 (0 - 6). The majority of patients had low (L) IPSS-M risk category (53%), followed by moderate low (ML) (19%) and very low (VL) (17%). Per IPSS-R, the majority had low-risk category (47%), followed by VL (38%) and intermediate (14%). Overall, 26 (25%) pt died after a median follow-up of 34 months and 21% progressed to MN (MDS 14 & CMML 8), and 1 patient with MDS and 1 with CMML progressed to secondary AML (2%). The median overall survival (mOS) was not reached, with a 2-year estimated (YE) OS and leukemia-free survival (LFS) of 80%. Predictive Power: When utilizing the IPSS-M risk category ( L, M, H) * by combining the risk categories into L *(L+VL), M * (ML+MH), and H *(H+VH) to overcome the low sample size limitation, it significantly predicted OS (p < .0001) ( Figure 1A) and median MN-free survival (FS) (p < .0001) ( Figure 1B). The 2YE-OS rates by IPSS-M risk category were as follows: VL - 93%, L - 87%, ML - 75%, high (H) - 25%, very high (VH) - 0% and the 2YE-OS rates by IPSS-M ( L, M, H) are summarized in Table 1B. IPSS-M hazard ratio (HR) for OS was 1.6 for ( M*) compared to 25 for ( H *) risk category (p < .0001). The ( L *) category, being the largest, was used as the reference level. Conclusion: This study provides the first real-world experience of using the IPSS-M and a modified version of the IPSS-M ( L, M, H) * risk category model to predict survival and progression into MN in CCUS (MUT) pt. The IPSS-M risk category was found to be a significant predictor of OS and MN-free survival. We propose that larger cohorts are needed to validate our findings.

SummaryVenetoclax (VEN) is an FDA‐approved selective inhibitor of B‐cell leukaemia/lymphoma‐2 (BCL‐2), used for treating elderly or unfit acute myeloid leukaemia (AML) patients unable to undergo intensive chemotherapy. Combining VEN with hypomethylating agents (HMAs) has shown impressive response rates in high‐risk myelodysplastic syndromes (MDS) and relapsed/refractory AML. However, the efficacy of VEN and HMAs in treating DDX41‐mutated (mDDX41) MDS/AML patients remains uncertain. Despite the favourable prognostic nature of mDDX41 MDS/AML patients, there is a lack of clinical experience regarding their response to different treatment regimens, leading to an unknown optimal therapeutic approach.