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Abstract Introduction Understanding the tumor immune microenvironment (TIME) in multiple myeloma (MM) is critical for identifying prognostic biomarkers and therapeutic targets. We hypothesized that specific immune cell populations within the bone marrow TIME are associated with clinical outcomes and could enhance patient stratification. To this end, we conducted the largest CyTOF-based immune profiling study to date in MM, profiling >300 million bone marrow immune cells from patients enrolled in the CoMMpass study. Methods We analyzed >1,000 bone marrow samples from ~700 newly diagnosed MM patients enrolled in the MMRF CoMMpass study (NCT01454297), using a harmonized protocol and 41-antibody CyTOF panel at five academic centers. The majority were baseline samples (n=671), with additional samples spanning up to 3.5 years post-diagnosis (n>300). Each site contributed ~200 samples on average. The cohort included 40% females, with a median age of 63 years and BMI of 27.8. ISS stages were evenly distributed (I: 36%, II: 36%, III: 29%), and 84% had ECOG 0-1. Autologous stem cell transplant was performed in 58% of patients, and 22% received maintenance therapy. Results We profiled 311 million single cells across the cohort, identifying major immune compartments: Neutrophils (36.0%), CD4 T cells (19.7%), NK cells (9.9%), monocytes (7.6%), B cells (5.7%), and CD8 T cells (5.6%). Less abundant populations included dendritic cells, γδ T cells, plasmablasts, and pDCs. In our preliminary analysis with multivariate cox regression modeling, we identified clinical factors including stem cell transplant, ISS stage, and ECOG status, as independent predictors of overall survival (OS). After adjusting for age and sex, higher proportions of naïve B cells, pDCs, and γδ T cells were independently associated with improved OS, while CD4+ T cell abundance was positively associated with prolonged progression-free survival (PFS). In contrast, elevated neutrophil proportions were significantly linked to inferior OS and demonstrated a trend toward shorter PFS. Longitudinal immune profiling in more than 200 patients identified a gradual accumulation of naïve B cells and a pronounced post-treatment rise in CD45+ plasmablasts, highlighting persistent B cell activity as a candidate mechanism for sustained therapeutic efficacy. Conclusion This study presents the largest immune proteomic atlas in MM to date, linking TIME composition to clinical outcomes. A favorable immune landscape was marked by preserved humoral immunity (naïve B cells, plasmablast expansion), enrichment of pDCs and γδ T cells, and lower neutrophil abundance, collectively associated with improved survival outcomes. These findings lay the groundwork for immune-guided prognostication and highlight new opportunities for therapeutic targeting in MM. Ongoing analyses aim to further resolve baseline and longitudinal immune dynamics in relation to treatment response.

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 Use of Direct oral anticoagulants (DOAC) has increased exponentially since their introduction in 2010. Over the years they have been used without any systematic oversight, there have been ongoing concerns related to inappropriate or incorrect dosing, incorrect duration, and non-adherence to the drugs leading to adverse patient outcomes. Several factors have been attributed to DOAC non-adherence such as presence or fear of adverse effects, affordability, lack of perceived benefit, or concerns for reversibility. These barriers impact both primary (first time prescription) and secondary adherence (longer term prescription). Poor adherence can lead to adverse outcomes such as stroke, death, and higher medical resource utilization hence increased cost to the patient and payors. This study was conducted as a quality improvement (QI) initiative to improve the adherence to the prescription DOACS. We included patients 18 years old, a diagnosis of Atrial fibrillation and flutter who had a primary care provider writing the prescription for chronic DOAC therapy. Patients with venous thrombosis, pregnancy or who were institutionalized were excluded. The charts were reviewed for primary and secondary adherence using Surescripts functionality which can provide baseline information about prescription fills from the participating pharmacies. In the preimplementation phase we identified 1030 patients meeting inclusion criteria associated with the pilot sites within Mayo Clinic practice in preceding 6 months. For this population, Surescripts data found that the rates of primary and secondary adherence to be 84% and 86% respectively. We then implemented a 6-month pilot where we created workflow for a pharmacy led DOAC management unit. Herein, once a DOAC prescription was made for patients meeting inclusion criteria, they would enter a registry where the pharmacy team would review the charts for primary adherence by utilizing Surescripts data. If adherent these patients would be marked for follow up in the secondary adherence phase. However, if non adherent, the team would initiate intervention including engagement with patient online services which was further escalated to phone calls by the pharmacy team. Once the barriers were identified several remediation approaches were incorporated in the process, these included education about DOACS, medicare education, social work assistance to even switching to warfarin if necessary. The same process was followed for secondary adherence management. In the intervention cohort, we had 411 patients during the pilot, for primary adherence 87.1% of patients were adherent at baseline and an additional 3.4% became adherent with interventions, while 9.5% remain nonadherent. The primary causes of nonadherence, amongst 9.5%, were cost (86%) while 1% were concerned about side effects and 3% were concerned about lack of perceived benefit. The inverntions lead to impoved adherence in most patients and very few patients were transitioned to warfarin. For secondary adherence 92% of the patients were adherent without any intervention, an additional 4% of patients benefited with the interventions of the DOAC management unit with approaches to address cost considerations, while another 4% remained nonadherent where cost remained the primary reason for nonadherence, other reasons being lack of perceived benefit and side effect concerns. In summary, with active intervention, in our patient population we were able to improve the primary adherence from 84% to 91% and secondary adherence from 86% to 96% . Cost remained the biggest barrier for adherence followed by concern for side effects and lack of perceived benefit. Our engaged team of pharmacy staff was able to manage those concerns with the education and cost mitigation strategies leading to improved adherence. Based on previously published literature even a 5% difference in adherence to DOACS can make a huge difference in population-based outcomes. Our work was able to demonstrate a positive impact of the intervention, highlighting the need for a well-managed DOAC unit especially for complex care populations.

Abstract Background: B-cell acute lymphoblastic leukemia (B-ALL) accounts for 0.3% of all new cancer cases and 0.2% of cancer-related deaths in the United States. While survival outcomes have improved over the years, further intensifying chemotherapy has offered diminishing returns. Blinatumomab, a bispecific T-cell engager targeting CD3 and CD19, has shown clinical benefit in minimal residual disease (MRD)-positive and relapsed/refractory settings. Its recent FDA approval for use in the consolidation phase of newly diagnosed Philadelphia chromosome–negative, CD19-positive B-ALL followed the landmark E1910 trial, which demonstrated a survival advantage when added to standard chemotherapy. We conducted a systematic review and meta-analysis to evaluate the efficacy and safety of blinatumomab in the consolidation phase across clinical trials and real-world studies. Methods: A comprehensive review was carried out on PubMed, Clinicaltrials.gov and Cochrane library from inception up to July 2025 using the terms “Blinatumomab” and “ALL”. Studies that evaluated response: overall response rate (ORR) and complete response (CR) and adverse events between Blinatumomab and control groups were included. Out of the 19 studies that met the inclusion criteria, 12 were clinical trials and 7 were observational studies. Open meta-analyst software was used to analyze the data. For single arm study, PLO (logit-transformed proportion) was used as a metric. Der Simonian-Laird random effects model was used to generate forest plots of pooled response rate estimates and 95% CI along with p-values and I2 statistics for heterogeneity. Results: A total of 824 patients were included (54.4% male, 45.6% female), with a median age of 48 years. The median follow-up across studies was 18.2 months (range, 3.4 to 92.8 months). Pooled ORR was 96.4% (95% CI, 93–98; p=0.955), and pooled CR was 92.7% (95% CI, 87–95; p<0.001). TRAEs leading to treatment discontinuation occurred in 6.8% (95% CI, 2.5–11.2; p=0.004), dose reductions in 2.9% (95% CI, 0.2–5.6; p=0.069), and treatment-related mortality in 1.4% (95% CI, 0.4–2.3; p=0.256). There was moderate heterogeneity across studies for toxicity outcomes. Conclusion: Consolidation-phase blinatumomab is associated with high response rates and a favorable safety profile, reinforcing the survival gains observed in E1910 (3-year OS: 83% vs 65%). With low rates of treatment-limiting toxicity and mortality, our findings support the incorporation of blinatumomab into standard adult B-ALL consolidation regimens. These data suggest that this immunotherapeutic approach may help narrow the outcome gap between adult and pediatric ALL.

Abstract Introduction Histiocytic neoplasms (HN) are a rare, heterogeneous group of hematologic disorders derived from myeloid-dendritic cell lineages. The most common forms include Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD), and Rosai-Dorfman disease (RDD). These disorders are driven by recurrent activating mutations in the MAPK pathway, most frequently involving BRAF, MAP2K1, PIK3CA, KRAS, and NRAS. This discovery enabled a major therapeutic advance with the use of BRAF and MEK inhibitors, resulting in durable responses. For patients harboring KRAS mutations, MEK inhibitors (MEKi) remain the primary therapeutic approach. However, the impact of KRAS mutation subtypes on treatment response remains poorly understood. Our study aimed to characterize the spectrum of KRAS mutations in LCH, ECD, and RDD and evaluate the responses to MEKi, providing insights to guide future treatment strategies. Methods We conducted a retrospective review of patients with LCH, ECD, and RDD who were evaluated at Mayo Clinic or University of Alabama at Birmingham. Patients were included if next-generation sequencing identified a KRAS mutation. The response assessment was based on radiographic evaluation under the most recent Histiocyte Society consensus guideline. Results We identified 23 patients with a KRAS mutation: 17 females (73.9%) and 6 males (26.1%), with a median age at diagnosis of 61 years (range, 20–78). RDD accounted for 73.9% (17/23) and ECD for 26.1% (6/23); no KRAS mutations were detected in LCH patients. The most frequent KRAS variants were p.K117N (34.8%), p.G12D (17.4%), p.A146T (13.0%), p.G13C (8.7%), and p.G13D (8.7%), with additional variants including p.T58I, p.A59G, p.A146P, and p.A146V. Mutation distribution differed by disease group: p.G12D was more common in ECD (50%) than RDD (5.9%) (p=0.01), whereas p.K117N occurred in 47.1% of RDD and was absent in ECD. Regarding treatment, 57% (13/23) received MEKi, all initially cobimetinib, with 1 patient switched to trametinib due to progression. Of the 10 patients who did not receive MEKi, 1 was treated with vemurafenib for a concurrent BRAF p.V600E mutation; 3 remained on observation; 2 underwent surgery without recurrence; 3 received other systemic therapies including corticosteroid, methotrexate, rituximab, lenalidomide, or sirolimus; and 1 developed diffuse large B-cell lymphoma, treated with R-CHOP. The overall response rate in the 12 patients on MEKi (excluding 1 patient too early for assessment) was 75%—3 (25%) CR and 6 (50%) PR (including 1 who initially progressed on cobimetinib but responded to trametinib). All 3 non-responders had RDD. Among the 5 patients with p.K117N, 3 had no response to cobimetinib, 1 achieved PR, and 1 achieved CR; notably, 1 non-responder switched to trametinib and achieved PR in 2 months. All 3 patients with codon 146 mutations achieved PR. Of the 2 patients with p.G12D, 1 achieved CR with a co-occurring MAP2K1 mutation, and 1 had no response. No additional genotype–response patterns were observed. Similar heterogeneity has been reported in prior studies. In a phase II cobimetinib trial, an ECD patient with p.R149G achieved PR, whereas another ECD patient with p.G12R and an LCH patient with p.G13C achieved CR in the presence of co-occurring ARAF and NRAS mutations, respectively. A retrospective cohort described an ECD patient with p.K117N achieving PR on dabrafenib and trametinib with a concurrent BRAF mutation and another with p.G12A achieving PR on trametinib. In a multicenter analysis of trametinib, a patient with p.A59T (co-occurring BRAF and NRAS mutations) had no response, whereas another with p.A146P achieved PR. Collectively, these findings, together with our data, underscore that KRAS-mutated histiocytoses exhibit heterogeneous responses to MEKi, likely influenced by variant type and co-mutations. Discussion KRAS mutations represent an important subset of MAPK pathway alterations in HN, although their prevalence varies by disease type and appears extremely rare in LCH, with no cases identified in our cohort. The most common variants include p.K117N and p.G12D, which may be linked to suboptimal response to MEKi in the absence of concurrent MAPK pathway alterations. As MEKi acts downstream, efficacy likely depends on the level of pathway activation conferred by specific KRAS variants. Larger studies are needed to confirm these observations and identify mutation-specific predictors to guide personalized treatment.

Abstract Introduction: Patients with multiple myeloma (MM) have an increased risk of infection secondary to hypogammaglobulinemia, due to myeloma itself and anti-myeloma therapies. Prophylactic immunoglobulin (Ig) supplementation has been considered a potential strategy to reduce the risk of infections. A randomized controlled trial (Chapel, Lancet, 1994) demonstrated a reduction in both overall and major infections with the use of Ig. However, its real-world benefit remains unclear and prophylactic Ig is not routinely given as part of standard therapies. Furthermore, little is known regarding the routine use of Ig in the context of modern therapeutic agents such as chimeric antigen receptor T-cell (CAR-T) therapy or bispecific antibody therapies. To address this gap, we conducted an updated systematic review and meta-analysis (SRMA) to elucidate the efficacy of prophylactic immunoglobulin in patients with MM. Methods: We performed a SRMA of observational and randomized controlled trials comparing the outcomes in patients with MM who received prophylactic immunoglobulin versus those who did not. A comprehensive search of PubMed, Scopus, and Cochrane CENTRAL databases was conducted up to July 2025, along with a manual review of the reference lists from relevant articles. This review adheres to the recommendations from the Cochrane Collaboration and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement guidelines. R software version 4.5.1 was used for statistical analyses. Results: A total of 18 studies were included in the systematic review. Among them, 11 studies compared patients who received immunoglobulin prophylaxis with those who did not (“Ig” versus “no Ig” groups). The remaining seven studies analyzed the same group of patients, comparing periods when they were receiving Ig (“on-Ig”) with periods when they were not (“off-Ig”). Among 18 studies, 13 studies were included in meta-analysis due to data availability (eight from the former group and five from the latter group). First, we conducted a meta-analysis of 1,234 patients from the eight studies that preceded this analysis, comparing Ig and no-Ig. Three studies included MM patients treated with bispecific antibodies, two focused on those treated with autologous stem cell transplantation (ASCT), and one on those treated with anti-CD38 antibodies. The dose of Ig was 0.4 g/kg every four weeks in most studies, and the timing of initiation of Ig varied across studies. The majority of Ig was delivered through an intravenous route. Most studies defined severe infections as those greater than grade 3 according to the Common Terminology Criteria for Adverse Events, while one study defined them as infections requiring intravenous or oral antibiotic treatment. The incidence of severe infection was significantly lower in patients who received prophylactic Ig compared with those who did not (odds ratio [OR] 0.22; 95% CI 0.08-0.63; p = 0.005). There was no significant difference in the overall infection rate between the two groups (OR 0.97; 95% CI 0.68-1.37; p = 0.85). A subgroup analysis by treatment type (chemotherapy, bispecific antibody, and ASCT) showed no significant differences in the overall infection rate among the subgroups (ASCT: OR 0.97; 95% CI 0.64-1.45; Bispecific antibody: OR 0.74; 95% CI 0.49-1.11). However, a significant reduction in the rate of severe infections was observed in patients treated with bispecific antibodies (OR 0.33; 95% CI 0.13-0.85; p = 0.021). Next, we analyzed 460 patients from the latter five studies comparing on-Ig and off-Ig. The incidence rate ratio (IRR) of overall infection was significantly lower during on-Ig periods compared with off-Ig periods (IRR 0.62; 95% CI 0.43-0.88; p = 0.0082). Conclusions: In patients with MM, prophylactic Ig use was associated with a low incidence of severe infections. Furthermore, the incidence rate ratio of overall infection was lower during periods of Ig prophylaxis compared to periods without Ig. These findings underscore the potential efficacy of a routine Ig prophylaxis in patients with MM to mitigate the risk of infections. Since this meta-analysis does not include studies involving patients treated with CAR-T therapy, further studies are warranted to evaluate the effectiveness of Ig in patients receiving novel therapies such as CAR-T therapy, while also considering the cost and time associated with Ig administration in real-world clinical practice.

Abstract Pseudouridine (Ψ) is the most prevalent RNA modification in human cells. Although Ψ was among the first post-transcriptional modifications discovered (1951), its biological functions remain poorly understood. More recently, Ψ was incorporated into COVID-19 mRNA vaccine, where it enhances RNA stability and reduces innate immune sensing. However, the precise roles of RNA Ψ in cancer, including leukemia, are largely unknown. Here, we identify RNA Pseudouridine Synthase D4 (RPUSD4) as a novel vulnerability in acute myeloid leukemia (AML) via directly catalyzing mitochondrial RNA (mt-RNA) Ψ formation. We further provide proof-of-concept evidence that targeting RPUSD4 suppresses leukemogenesis and stimulates anti-leukemia immunity. To investigate whether RNA Ψ dysregulation is involved in leukemia, we first compared RNA Ψ levels between primitive CD34+ cells (LSC-enriched) and CD34- bulk cells from multiple primary AML specimens. CD34+ AML cells exhibited significantly elevated RNA Ψ levels. We also examined Ψ levels across various RNA types in AML cells, identifying that mt-RNA contained much higher Ψ levels than other RNA types. These findings imply that RNA Ψ, particularly mt-RNA Ψ, may play a role in LSC biology and leukemogenesis. Further unbiased CRISPR screening revealed RPUSD4 as the most critical Ψ synthase for LSC maintenance. Large-scale transcriptomic and patient data analyses showed that RPUSD4 is highly expressed in AML specimens (P = 3.5 × 10-9), particularly within LSCs (P = 1.4 × 10-18). RPUSD4 knockout (KO) significantly suppressed AML proliferation, reduced mitochondrial OxPhos, and decreased LSC frequency in vitro and substantially delayed AML progression in vivo (MLL-r and FLT3ITD models). Of note, RPUSD4 KO-mediated anti-leukemia effects could be fully rescued by wild-type but not catalytically inactive RPUSD4 both in vitro and in vivo, demonstrating that Ψ synthase activity is essential for its function in leukemia. To profile RPUSD4-dependent Ψ sites, we applied two orthogonal technologies, direct nanopore sequencing and PRAISE sequencing (PMID: 36997645), both capable of detecting Ψ at single-base resolution. These approaches converged on a single RPUSD4-dependent Ψ at position 3,067 on mt-16S rRNA. This Ψ site is essential for maintaining rRNA stability. RPUSD4 KO induced mt-16S rRNA decay, thereby suppressing mitochondrial translation. This led to OxPhos inhibition, growth suppression, and LSC eradication in AML. Mechanistically, RPUSD4 is exclusively localized in mitochondria, where it directly interacts with the mt-RNA exonuclease PNPase. Under physiological conditions, PNPase resides within mitochondria and degrades mt-RNA to prevent accumulation of mitochondrial double-stranded RNA (mt-dsRNA). Upon RPUSD4 depletion, PNPase translocates from mitochondria to the cytosol, resulting in two major consequences: (i) mRNA decay:Cytosolic PNPase degrades mRNAs, particularly the nuclear-encoded mitochondrial mRNAs, such as DHODH(Dihydroorotate dehydrogenase). By retrogradely upregulating DHODH, RPUSD4 promotes de novo pyrimidine synthesis in AML. (ii) Aberrant mt-dsRNA accumulation: The buildup and cytoplasmic release of mt-dsRNA activates “viral mimicry” response that sensitizes AML cells to T cell cytotoxicity. Finally, to therapeutically target RPUSD4, we developed an RNA-based inhibitor, CpG-siRNARPUSD4, by conjugating a specific RPUSD4 siRNA to a Toll-like receptor (TLR9) ligand. CpG-siRNARPUSD4 is specifically internalized by TLR9+ cells, including AML cells, thereby maximizing selectivity and minimizing toxicity. Preclinical studies demonstrate that pharmacologically targeting RPUSD4 significantly prolonged survival across multiple AML models, including patient-derived xenograft (PDX) models, and rendered AML cells more susceptible to T cell–mediated cytotoxicity. Furthermore, the RPUSD4 inhibitor exhibited a promising synergistic effect with DHODH inhibitor in treating relapsed AML in vivo. For instance, in a representative relapsed PDX model, median survival times (in days) were: Ctrl – 28, RPUSD4 inhibitor – 36, DHODH inhibitor – 39, and combination – over 60. In conclusion, our findings uncover a previously unrecognized role of RPUSD4 and mt-RNA Ψ in leukemic metabolism, anti-leukemia immunity, and LSC maintenance. This study also bridges a critical knowledge gap regarding the role of RNA Ψ in leukemogenesis.

Abstract Introduction: Targeted therapy yields deep and durable response in histiocytic neoplasms.However, relapse rate following interruption is high at 75-77%, with a median time to relapse 6-9 months in previous studies. Outcomes after discontinuation in those who have already achieved a durable response are not well understood and are the focus of this study. Methods: We performed a multicenter retrospective study, including 4 US centers, including patients with histiocytic disorders treated with BRAF inhibitor (BRAFi), MEK inhibitor (MEKi), or combination BRAF/MEKi, and whose therapy was interrupted after ≥12 months of therapy following a best response of partial (PR) or complete response (CR). Progression-free survival (PFS) and overall survival (OS) were analyzed with Kaplan-Meier method. Cox regression was performed to identify clinical and molecular factors that are associated with PFS. Results: 26 patients were included (median age 55 [range 12-72]; male 53.8%; Caucasian 69.2%). Most predominant histology was Erdheim-Chester Disease (ECD) (n=15, 57.5%), followed by mixed histiocytosis (n=5, 19.2%). Rosai-Dorfman Disease (RDD) (n=4, 15.4%), and Langerhans Cell Histiocytosis (LCH) (n=2, 7.7%). All had BRAF V600E analysis and 10 (38.5%) were positive. 19 patients underwent additional molecular testing; alternative mutations identified included MAP2K1/2 (n=6, 23.1%), NRAS (n=1, 3.8%), RAF1 (n=1, 3.8%), ASXL1 (n=1, 3.8%), and SRSF2 (n=1, 3.8%). Targeted therapy was given as frontline therapy (n=8, 30.8%) or in the relapsed refractory setting (n=18, 69.2%) with median 1 prior line of therapy (range 0-7). Targeted therapies include BRAFi (n=5, 19.2%; 2 dabrafenib, 3 vemurafenib), MEKi (n=17, 65.4%; 14 cobimetinib, 3 trametinib), and BRAF/MEKi (n=4, 15.4%; 3 dabrafenib/trametinib, 1 vemurafenib/cobimetinib). PR and CR occurred in 8 (30.8%) and 18 (69.2%) patients, respectively. The median duration of treatment was 32 months (range 13-60) (12-24 months: 9 [34.6%]; 24-36 months: 7 [26.9%]; >36 months: 10 [38.5%]). Median time from initiation of targeted therapy to best response was 6 months (<6 months: 14 [53.8%]; 6-12 months: 5 [19.2%]; >12 months: 7 [26.9%]). Median duration from best response to drug discontinuation was 19 months (12-24 months: 14 [53.8%]; 24-36 months: 7 [26.9%]; >36 months: 5[19.2%]). Reasons for drug discontinuation include toxicity (n=8, 30.8%), patient preference (n=13, 50.0%), cost prohibition (n=1, 3.8%), and other critical medical conditions (n= 4,15.4%). Eleven patients (42.3%) experienced disease progression after discontinuation of targeted therapy, 5 patients progressed within 6 months. Systemic and CNS progression were captured by PET/CT and MRI brain, respectively. At median follow-up of 33.0 months (95%CI 24.3-47.1), median PFS, defined by time from targeted therapy discontinuation to progression or death, was 29 months (95% confidence interval [CI] not estimable). Median OS was not reached. In Cox regression model, BRAF V600E mutation (hazard ratio [HR] 4.16, 95% CI 1.10-15.70, p 0.036) and CNS involvement (HR 4.64, 95% CI 1.21-17.67, p 0.025) were associated with inferior PFS. MEKi containing regimen trended toward improved PFS (HR 0.35, 95%CI 0.10-1.21, p 0.097). There was no difference in PFS when assessing demographics, histology, prior therapies, best response to targeted therapy, treatment duration, or time from best response to discontinuation. Of the 11 patients with progression, 9 were re-challenged with targeted therapy (7 switched class), 2 did not receive next line therapy (1 transitioned to hospice and passed from progression, 1 has pending evaluation for next line therapy). Of 6 with response assessments, all recaptured response (1 CR, 5 PR), and none had progressed by data cutoff. Conclusions: In patients with histiocytic neoplasm and prior durable response to targeted therapy, ~40% experienced disease progression after treatment discontinuation. BRAF V600E mutation and CNS disease are associated with inferior PFS, suggesting these subgroups may not be appropriate for limited duration of treatment. Novel approaches are needed in these high-risk patients.

Abstract Background: Infections account for over half of the non-relapse deaths among chimeric antigen receptor (CAR) T-cell recipients. Non-relapse mortality estimates are among the highest in patients with relapsed / refractory multiple myeloma (RRMM) receiving B-cell maturation antigen (BCMA)-directed CAR-T cell therapy. The current Center for International Blood and Marrow Transplantation Research (CIBMTR) study analyzed the burden, types, risk factors, and outcomes of infection and its impact on survival in 807 patients with RRMM receiving commercial idecabtagene vicleucel (ide-cel) CAR-T therapy from March 2021 to December 2023. Methods: The primary endpoint was infection density for overall infections and for organism type (bacterial, viral, or fungal) within 100 days post-CAR-T infusion. Infection density was estimated as the number of infections per 100 person days at risk, stratified into two distinct time intervals following CAR-T cell infusion: days 0-30 and days 31-100.Additional endpoints included the cumulative incidence of infections, infection-related mortality (IRM), and overall survival (OS). Multivariable Cox proportional hazards models were employed to identify factors associated with infectious complications within 100 days post-CAR-T cell infusion. Pre-specified risk factors were considered for the multivariable analysis (MVA) models. We further examined the impact of infections within 100 days of CAR-T on OS at any time beyond 100 days following CAR-T infusion. Results: Infections developed in 114 (14.1%) patients within 30 days and 226 (28%) patients within 100 days post-CAR-T infusion, resulting in an overall infection density of 0.49 per 100 patient-days and a 100-day cumulative incidence of 27.2%. Proportions of bacterial, viral, and fungal infections within 30 days of ide-cel infusion were 82 (10.2%), 50 (6.2%), and 5 (0.6%), respectively. Similarly, proportions of bacterial, viral, and fungal infections within 100 days of CAR T-cell infusion were 126 (15.6%), 125 (15.5%), and 8 (1%), respectively, with corresponding infection densities of 0.23, 0.22, and 0.012 per 100 patient-days. The 100-day cumulative incidence of bacterial, viral, and fungal infections were 14.1% (95% CI, 11.8-16.6%), 14.4% (95% CI, 12-16.9%), and 0.9% (95% CI, 0.3-1.6%) respectively. The 100-day IRM was 1.1% (95% CI, 0.5-2%). With a median follow-up of 11.6 months (1.1-26.7), 222 (27.5%) patients died, and infection was the primary cause of death in 17 cases (7.7%). In MVA, Karnofsky performance score ≤80 (p<0.001), infection prior to CAR-T cell infusion requiring with ongoing treatment after d+0 (p<0.001), cytokine release syndrome grade ³2 (p=0.002), and severe immune effector cell-associated neurotoxicity syndrome [ICANS] (grade ≥3) (p<0.001) were associated with an increased infection risk within 100 days post-infusion. Similarly, infection prior to CAR-T infusion requiring with continuing treatment after d+0 (p<0.001 for bacterial and p=0.003 for viral infections) and grade ≥3 ICANS (p<0.001 for bacterial and p=0.015 for viral infections) significantly conferred a heightened risk for bacterial and viral infections within 100 days of CAR-T infusion. Number of infections within 100 days (hazard ratio [HR], 2.36 for ≥2 vs. 0 infections; 95%CI, 1.48-3.77; p<0.001), extramedullary disease or plasma cell leukemia (HR, 1.8; 95%CI, 1.19-2.74; p=0.006), and prior BCMA-directed therapy (HR, 1.57; 95%CI, 1.06-2.33; p=0.025) were independent risk factors for inferior OS beyond day+100 after CAR-T therapy. Intravenous immunoglobulin (IVIG) replacement post-CAR-T therapy conferred a survival advantage (HR, 0.52; 95%CI, 0.38-0.72; p<0.001). Conclusion: In conclusion, study results demonstrate a significant incidence of infections for a prolonged duration (14.1% in the first 30 days and 28% in the first 100 days) in patients with RRMM undergoing ide-cel therapy. Notably, viral infections increased beyond d+30. Multiple infections (≥2 episodes) were associated with inferior OS. Results identify patients at an increased risk for infection and provide insights into risk-adapted interventions to mitigate infections and improve patient outcomes. Furthermore, continued surveillance for infection pre-emption and prevention beyond 3 months post-CAR T therapy may be necessary to reduce infection burden and IRM. Prophylactic strategies such as IVIG replacement could potentially modify infection risk in patients with RRMM receiving ide-cel.

Abstract Introduction: Multiple myeloma (MM) predominantly affects older adults who vary widely in physiological status and treatment outcomes. Comprehensive Geriatric Assessment (CGA) is considered the gold standard for frailty assessment in older cancer patients (pts), but clinical useis limited. Current frailty tools for MM include only select GCA domains, rely on trial datasets, and do not incorporate pt-reported outcomes (PROs). Since their development, treatment strategies have evolved with the use of anti-CD38 MAbs and quadruplets in older pts. The impact of geriatric impairments on treatment tolerance in the era of modern therapy remains unclear and changes in geriatric domains during treatment are not well characterized. Aim: This prospective study evaluates the association between pt-reported CGA and treatment outcomes in older MM pts.Methods: We included MM pts ≥60 years initiating a new treatment at Mayo Clinic from March 2023-June 2024. Pts completed the CARG GCA (Hurria et al 2005) electronically prior to and after 4 treatment cycles. We collected data on toxicity using CTCAE and PRO-CTCAE and quality of life using the PROMIS10-GH SF.Results: Ninety pts were enrolled. Median age was 72 (range: 63-86), 42% female, and >90% non-Hispanic white. Over half (59%) were newly diagnosed with 41% and 56% receiving quadruplets and triplets, respectively. Among newly diagnosed pts, 34% had early stem cell transplant. Baseline median self- and physician- reported KPS were 80% and 90%, respectively, with high correlation (r=0.657). The median number of meds per pt was 9 (range:0-30), 39% had ≥3 comorbidities, 21% reported ≥1 fall in the past 6 months, and 40% reported ≥1 IADL limitation. On the Hospital Anxiety and Depression Scale, 3% and 7% had anxiety and depression, respectively. On the Blessed Orientation-Memory-Concentration test, 19% had mild cognitive impairment, and 1% had severe cognitive impairment. While only 19% had grade (G) ≥3 non-hematologic toxicity by CTCAE, 71% had ≥1 treatment delay, dose reduction, or discontinuation, and 39% had ≥1 ED visit or unplanned hospitalization within the first 4 cycles. This suggests physician grading of non-hem toxicities may inadequately capture toxicity burden from MM therapy. Notably, the rate of G≥3 toxicity by PRO-CTCAE was 49%, highlighting the discrepancy between physician- and pt-reported symptom burden. CGA domains significantly associated with G≥3 non-hem toxicity were: age (74 v 71.5, p=0.032), ≥3 comorbidities (65% v 33%, p=0.015), anxiety (18% v 0%, p=0.006), ≥1 IADL limitation (65% v 33%, p=0.018), physician KPS ≤80 (53% v 27%, p=0.042), limitations in vigorous activities (100% v 78%, p=0.023) and limitations in climbing several flights of stairs (88% v 56%, p<0.001). Predictors of PRO-CTCAE G≥3 toxicity were ≥1 falls (30% v 11%, p=0.030), ≥3 comorbidities (52% v 26%, p=0.011), polypharmacy (≥9 meds) (67% v 43%, p=0.023), and physician KPS ≤80 (43% v 22%, p=0.030). CGA domains associated with ≥1 treatment adjustments were polypharmacy (62% v 33%, p=0.017) and unintentional weight loss (35% v 12%, p=0.028). Polypharmacy was the only domain associated with healthcare utilization (68% v 45%, p = 0.040), which may reflect underlying multimorbidity and greater pain burden. On multivariable logistic regression, any level of limitation in climbing several flights of stairs (OR: 6.0, 95% CI 1.2-30.3; p= 0.030) and older age (OR: 1.1, 95% CI 1.0-1.1; p=0.032) were independently associated with G≥3 non-hem toxicity, reflecting impaired functional status and reduced physiologic reserve, while ≥3 comorbidities only trended toward significance (OR:1.9, 95% CI 1.1-3.9, p=0.051).Compared to baseline, there were no significant changes in CGA domains or PROMIS10 scores after 4 cycles. While there was no significant difference in the proportion of pts reporting limitations in IADLs or physical function, we observed heterogeneity among individual pts, with changes in all 3 directions (improvement, stability, and decline). Conclusions: Geriatric impairments are prevalent in older pts with MM; pt-reported impairments are significantly associated with G≥3 non-hem toxicities, need for treatment modifications, and increased healthcare utilization, even in the era of novel therapies. Physical functional trajectories during treatment are variable among individual pts, underscoring the need for personalized treatment strategies and reassessment of geriatric domains throughout treatment.