Citations

334 Background: Sarcopenia, or decreased skeletal muscle mass, has been associated with worse surgical and oncologic outcomes across multiple malignancies. This study investigates the impact of sarcopenia on outcomes after multimodal therapy for esophageal cancer. Methods: Retrospective observational cohort study including adult patients who underwent neoadjuvant therapy followed by esophagectomy for primary esophageal cancer from January 2000 - December 2021. A fully automated abdominal segmentation using deep convolutional neural network was utilized to calculate skeletal muscle index (SMI) from preoperative CT scans performed at our institution. Males with SMI <52.4 cm 2 /m 2 and females with SMI <38.5 cm 2 /m 2 at any point before surgery were classified as sarcopenic. The relationship between sarcopenia and patient demographics, operative details, and complications were explored using chi-square tests. The relationship between sarcopenia and disease-free survival and overall survival were investigated using parsimonious multivariable analysis retaining variables with p-value <0.05 using backward selection method. Results: We identified 200 patients meeting the study criteria with 142 (71%) having sarcopenia at any time prior to surgery. Patients with sarcopenia were significantly older [65.2 (59.6, 71.2) vs 63 (53.6, 67.5), p = .023] and more likely to have had open surgery [129 (90.8%) vs 46 (79.3%), p = .034]. There were no significant differences in sex, history of diabetes, coronary artery disease, renal disease, smoking, cancer type, cancer stage, tumor size, tumor location, or margin status between sarcopenic groups ( p > .05). Sarcopenic patients were significantly more likely to require blood transfusion ≥3 units after esophagectomy [79 (55.6%) vs 8 (13.8%), p < .001] or to experience complications requiring surgical intervention [36 (24.6%) vs 7 (12.1%), p = .048]. Multivariate analysis revealed that sarcopenia was associated with disease-free and overall survival (Table). Conclusions: Sarcopenia is a prognostic factor in patients undergoing multimodal therapy for esophageal cancer. Interventions that aim to prevent decreases in SMI after initiating neoadjuvant therapy should be investigated. Multivariate analysis with sarcopenia predicting outcomes. Disease free survivalHR (95% CI) p-value Overall survivalHR (95% CI) p-value Age 1.04 (1.02, 1.06) < .001 1.04 (1.02, 1.07) < .001 Epicenter Middle Upper 1.88 (1.21, 2.86)3.16 (1.67, 5.98) .001.005< .001 1.96 (1.26, 3.04)4.00 (1.90, 8.44) < .001.003< .001 Stage Stage II Stage III Stage IV 1.88 (0.95, 3.71)2.90 (1.46, 5.75)16.02 (6.12, 41.93) < .001.069.002< .001 1.65 (0.83, 3.25)2.76 (1.37, 5.55)10.14 (4.03, 25.53) < .001.151.005< .001 Cancer type - - 1.76 (1.03, 3.02) .039 Transfusion > 3 pRBC - - 1.54 (0.99, 2.40) .057 BMI prior to cancer diagnosis - - 0.98 (0.94, 1.01 .208 Sarcopenic 1.76 (1.16, 2.67) .007 1.64 (1.04, 2.60) .033

Objective: The Society of Critical Care Medicine PICU Liberation ABCDEF (A–F) Campaign Collaborative aimed to implement best practices for analgesia (A), breathing (B), comfort/consciousness (C), delirium (D), early mobilization (E), and family engagement and empowerment (F). Our post hoc study of Mayo Clinic data sought to compare the pre-implementation rounding process, which used a nursing script organized by organ systems, with a novel, liberation-focused rounding process emphasizing A–F bundle elements. Design: Secondary analysis of pre- vs. post-implementation surveys collected by independent observers during rounds. Setting: Medical/surgical PICU in a quaternary-care, academic medical center during April to July 2017. Subjects: The observed participants included PICU physicians, nurses, respiratory therapists, pharmacists, and dietitians. Interventions: None. Measurements and Main Results: Survey responses from 145 team members pre-implementation and 67 post-implementation showed improved team satisfaction, communication, and understanding of daily plans (all p < 0.05). Respondents reported an increased frequency of discussions on bundle components A–E (all p < 0.01). Observations of 41 pre-implementation and 46 post-implementation rounds showed an increase in the frequency of discussion of all components of the bundle (all p < 0.01). However, this finding was not at the expense of increased duration of individual rounds since we failed to find a difference in pre- vs. post-implementation duration per patient (480 vs. 544 s per patient, p = 0.20). Conclusions: In 2017, around the time of introducing the nurse-led PICU Liberation rounding process to our practice, we found that after implementation, there was an associated increase in discussions about bundle elements and improved communications and satisfaction in team members.

Abstract Background Progressive supranuclear palsy (PSP) is a devastating neurodegenerative disorder with rapid progression to death. Multiple efforts to develop a disease‐modifying therapy for PSP have yet to succeed. We previously reported the discovery of three potential therapeutic targets for PSP. These three genes, DDR2, KANK2, and STOM, are consistently upregulated in the brains of PSP patients and mouse models of tauopathy. Reducing their expression in a drosophila model significantly rescued the tau‐induced eye degeneration and tau seeding activity. To translate these targets into the clinic, we are developing antisense oligonucleotides (ASO) as potential therapies. Method We screened candidate ASOs in neuroglioma cell line H4. ASO hits were validated for their potency and safety. We also used iPSC‐derived neurons from PSP patients to test the potency and potential toxicity of our ASOs. To investigate target engagement, therapeutic efficacy and preliminary pharmacodynamic properties, we treated iPSC‐derived midbrain organoids with the ASO leads. Lastly, we will assess the off‐target effects of the ASOs by investigating the levels of mRNA transcripts that share similar sequences as our targets using RNAseq. Result Our in vitro screening identified ASO leads that significantly reduce the target gene expressions at mRNA and protein levels in a dose‐dependent manner. The ASO hits also exhibit low cellular toxicity in the H4 cell line. Upon treating iPSC neurons with ASO hits, we were able to validate the dose‐dependent reduction of target mRNAs. Cell viability analysis indicated low toxicity, suggesting that these ASOs are potent and safe. In midbrain organoid model, DDR2‐targeting ASO showed time‐dependent target engagement and were prioritized for further development. Conclusion We developed candidate therapeutics for PSP using ASOs that silence novel therapeutic targets discovered in our systems based cross‐species screening. We showed that our ASOs have low toxicity and confirmed target engagement at both mRNA and protein levels in vitro. The results suggest a favorable preclinical profile of our ASO leads that warrants additional investigations. Importantly, PSP shares congruent pathophysiological changes with other tauopathies, such as Alzheimer’s disease. These common perturbed pathways indicate that our ASOs can be potentially repurposed for multiple neurodegenerative tauopathies.

ABSTRACT Background and Aims Chronic inflammatory demyelinating polyradiculoneuropathy ( CIDP ) is a common, treatable, autoimmune, neuropathy frequently misdiagnosed. The complex electrodiagnostic ( EDX ) criteria required for diagnosis are challenging to apply in routine practice. This study evaluates the effectiveness of a machine‐assisted EDX tool in real‐time identification of demyelinating nerve conduction studies ( NCS ) stipulated by 2021‐ EAN / PNS CIDP criteria in conjunction with an online CIDP clinical probability calculator. Methods We prospectively evaluated 100 consecutive patients with referral or EDX diagnosis of polyradiculoneuropathy beginning January 1, 2024. Fifty patients were included, each from Jacksonville and Rochester Mayo Clinics. Routine electromyography ( EMG ) reports were compared to a machine‐assisted support tool applying 2021‐ EAN / PNS CIDP EDX criteria to NCS assessing demyelination. The EDX ‐assistant performance was compared to the final clinical diagnosis and our previously reported online CIDP clinical prediction tool ( https://news.mayocliniclabs.com/cidp‐calculator/ ). Results Among 100 patients (60% male; median age 64), 30 had a final clinical CIDP diagnosis with 29 having intravenous immunoglobulin follow‐up; 27 (93%) improved and 2 (7%) stabilized. Routine EMGs reported demyelination in 14 of 30 (47%), with 46% sensitivity and 79% specificity. The EDX ‐assistant identified CIDP demyelination in 28 of 30 (93%), with 93% sensitivity and 57% specificity. The clinical calculator detected CIDP in 30 of 30 (100%) with 86% specificity, increasing to 94% after excluding false positives lacking demyelinating features on the EDX tool. Interpretation A real‐time machine‐assisted EDX support tool, used with a clinical web‐based calculator, streamlines CIDP assessment by improving standardized identification of 2021‐EAN/PNS CIDP demyelinating NCS criteria and aiding clinical decisions.

PURPOSE To compare patient-reported and clinical outcomes between radical cystectomy (RC) and bladder-sparing therapy (BST) in patients with recurrent high-grade non–muscle-invasive bladder cancer (NMIBC). PATIENTS AND METHODS This pragmatic, prospective observational cohort study was designed with patients, who selected and prioritized outcomes. Eligible adults were candidates for both RC or BST, had previous induction Bacillus Calmette-Guérin (BCG), and received their last treatment within 12 months. The primary outcome was the EORTC-QLQ-C30 physical function scale at 12 months. Secondary outcomes included other EORTC-QLQ-C30 scales, depression, anxiety, bladder cancer–specific quality of life (QOL), financial burden, and cancer-specific outcomes. Targeted maximum likelihood estimation (TMLE) was used to calculate average treatment effect (ATE) estimates between arms. Inverse probability weighted risk ratios (wRR) were calculated using quasi-Poisson regression. RESULTS Of 570 participants (mean age 71.4 years; 21% female), 371 selected BST and 199 selected RC. Physical function was significantly worse in the RC arm at 3 months; by 9 months, there was no difference between arms, and at 12 months, physical function did not differ (ATE, 0.9; 95% CI, –0.6 to 2.4; P = .22). RC was associated with better emotional function, generic health-related QOL, and financial burden, and lower depression and anxiety, while BST was associated with better bowel and sexual health. Cancer-specific survival was 99% for BST versus 96% for RC (wRR, 0.99; 95% CI, 0.97 to 1.01). RC was associated with a higher risk of adverse events and serious adverse events, including a 90-day mortality rate of 2.5%. CONCLUSION Most patient-prioritized outcomes were similar or better among participants who chose RC compared with BST. These findings support the continued role of RC in managing recurrent high-grade NMIBC.

PURPOSE Low-grade serous carcinoma (LGSOC) of the ovary, fallopian tube, or peritoneum is a hormonally driven, relatively chemoresistant malignancy with limited treatment options in the recurrent setting. Given frequent estrogen receptor (ER) expression and dysregulation of the cyclin-dependent kinases 4 and 6 (CDK4/6)–p16–Rb pathway, features shared with hormone receptor–positive breast cancer, dual endocrine, and CDK4/6 inhibition is a biologically rational strategy. This phase II trial evaluated ribociclib plus letrozole in recurrent LGSOC. METHODS This open-label, single-arm, multicenter phase II study enrolled women with measurable, recurrent LGSOC. Patients received ribociclib (600 mg orally, once daily, days 1-21 of a 28-day cycle) and letrozole (2.5 mg orally, once daily). The primary end point was investigator-assessed objective response rate (ORR) per RECIST 1.1. Secondary end points included clinical benefit rate (CBR), progression-free survival (PFS), overall survival (OS), and safety. RESULTS Of 74 patients screened, 51 were enrolled and 49 treated. The confirmed ORR was 30.6% (90% CI, 19.9 to 43.2), including one complete and 14 partial responses. Among responders, the median duration of response was 21.2 months. The CBR was 84% (90% CI, 72.5 to 91.6). The median PFS was 14.5 months (90% CI, 10.1 to 28.8), and the median OS was 44.5 months (90% CI, 31.8 to not reached). The most common grade ≥3 adverse event (AE) was neutropenia (47%), managed with dose modifications. Three grade 5 events (6%) occurred but were unrelated to treatment. Treatment discontinuation because of AEs occurred in 4%. No dose-limiting toxicities were observed. CONCLUSION Ribociclib plus letrozole met the primary end point, achieving meaningful response rates and durable disease control in recurrent LGSOC. The safety profile was consistent with prior CDK4/6 inhibitor studies. This combination represents a therapeutic option in this rare and genomically distinct subtype.

PURPOSE Venetoclax, an oral BCL-2 inhibitor, has efficacy in t(11;14)-positive relapsed/refractory multiple myeloma (RRMM), which is enhanced by dexamethasone, which promotes BCL-2 dependency. METHODS The randomized, open-label, phase III CANOVA study (ClinicalTrials.gov identifier: NCT03539744 ) enrolled adults with t(11;14)-positive RRMM who had received ≥2 previous lines of therapy. Patients were randomly assigned (1:1) to venetoclax-dexamethasone or pomalidomide-dexamethasone until progression or intolerable toxicity. The primary end point was independent review committee assessed–progression-free survival (PFS) in the intention-to-treat population analyzed by stratified log-rank test (two-sided type I error rate, α = .05), with hazard ratio (HR) and 95% CI estimated by stratified Cox proportional hazard model. Secondary end points included response rates, overall survival (OS), minimal residual disease (MRD) negativity rate (<10 –5 ), and safety. RESULTS Overall, 263 patients were randomly assigned (venetoclax-dexamethasone, n = 133; pomalidomide-dexamethasone, n = 130). Median PFS was 9.9 months (95% CI, 6.9 to 12.6) with venetoclax-dexamethasone versus 5.8 months (95% CI, 3.8 to 9.2) with pomalidomide-dexamethasone (HR, 0.823 [95% CI, 0.596 to 1.136]; P = .24). Overall response and very good partial response or better rates were 62% and 39%, respectively, with venetoclax-dexamethasone versus 35% and 14% with pomalidomide-dexamethasone. MRD negativity rate was 8% with venetoclax-dexamethasone and 0% with pomalidomide-dexamethasone. Median OS was 32.4 months (95% CI, 26.4 to 40.7) with venetoclax-dexamethasone and 26.9 months (95% CI, 20.4 to 38.9) with pomalidomide-dexamethasone (HR, 0.856 [95% CI, 0.612 to 1.197]). Grade ≥3 treatment-emergent adverse event rates were 67% with venetoclax-dexamethasone versus 83% with pomalidomide-dexamethasone. There were 16 (12%) treatment-emergent deaths with venetoclax-dexamethasone versus 8 (6%) with pomalidomide-dexamethasone. CONCLUSION The primary end point of PFS was not met. PFS and OS were numerically longer with venetoclax-dexamethasone versus pomalidomide-dexamethasone in t(11;14)-positive RRMM. Consistent with previous studies, infections were associated with venetoclax-dexamethasone; no new safety signals were observed.

Abstract Introduction: Older adults (OAs) with classic Hodgkin lymphoma (cHL) have inferior survival compared with younger patients (pts). NAVD has been widely adopted in clinical practice for frontline (1L) treatment of OAs with advanced stage cHL based on the subset analysis of S1826 study (Rutherford et al, JCO 2025) showing a 1-year progression-free survival (PFS) of 93% and 1-year overall survival (OS) of 95% after NAVD (n = 50) which remained durable on longer-term follow up. Another phase 2 study (Torka et al, JCO 2025) showed that NAVD is a highly effective and well-tolerated 1L regimen in OAs with cHL (n=40) across a wide range of geriatric impairments. Adverse events (AEs) and efficacy have not been reported in OAs treated with NAVD outside of a clinical trial. Hence, we sought to evaluate safety profile and efficacy outcomes of OAs with cHL treated with 1L NAVD in a real-world setting (RWS). Methods This is a multicenter retrospective cohort study of adults (≥18 years) with cHL treated with 1L NAVD between 2023 and 2025 at 20 US academic sites. Baseline characteristics and outcomes of pts ≥60 years were evaluated as a pre-planned subset analysis. The safety evaluable cohort received at least 1 cycle of NAVD and included pts who had not yet completed treatment. The efficacy evaluable cohort had completed 6 cycles of treatment including end of treatment (EOT) PET-CT and included pts who intended to complete treatment but died or discontinued due to progressive disease or AEs. The primary endpoint was EOT overall response rate (ORR). Secondary endpoints included EOT complete response rate (CRR), PFS and OS. PFS and OS were analyzed using the Kaplan Meier method. Results Among 311 pts, 81 were OAs (26%). Median age of the OA cohort was 70 (range 60-88) yrs, 65% male, 84% Caucasian, 71% nodular sclerosis subtype, 58% stage 4 disease, 59% B symptoms, 14% bulky disease (&gt;7.5 cm), 69% extranodal sites, 41% EBV positive, 54% hypoalbuminemia, 49% IPS ≥ 4 and10% had an autoimmune disease. G-CSF was given in 81% pts. All 81 pts were evaluable for safety; 74% experienced a grade 3+ (≥G3) AE, 54% had ≥G3 hematological AE, 48% had ≥G3 neutropenia, 17% had febrile neutropenia. Infection rate was 28% with 10% ≥G3, neuropathy rate was 23% with 4% ≥G3. One infusion reaction was noted. Treatment related hospitalizations rate was 23% with median duration of 7 (range 1-16) days. There were 24 immune related AEs (IrAE) (30%) of which 5 were ≥G3. Most common IrAE was hypothyroidism (n=5), followed by inflammatory arthritis (n=4), pneumonitis (n=2, ≥G3, n=1), hepatitis (n=2, both ≥G3), adrenal insufficiency (n=2, ≥G3, n=1), colitis (n=2), and rash (n=2). One patient each had autoimmune neutropenia, sarcoidosis of lung/skin and myocarditis (≥G3). Overall, 15% pts required steroids with resolution of IrAEs in 56% cases, 30% (n=7) pts required continued therapy (levothyroxine in 4 pts, steroids in 3 pts, medical tx for heart failure in 1 pt). Treatment was interrupted in 22%, reduced in 22%, and discontinued in 23% pts. Nivolumab was discontinued in 14% pts. Among all pts (n=81), 81% had an interim PET-CT after 2-4 cycles. The ORR and CR rate at interim PET-CT were 100% and 81%, respectively. In the efficacy evaluable pts (n=52; 24 still on therapy), the EOT ORR and CRR were 93.2% and 84% in OAs compared to 96.8% and 91.7% in pts &lt;60yrs, respectively. At a median follow up of 10.2 mo (range 0.27-28.52), the 1-yr PFS was 90.6% (95% CI: 82.7%-99.3%) in OAs and 95.5% (95% CI: 91.6%- 99.6%) in pts &lt;60 yrs (p=0.044). 1-yr OS was 97.5% (95% CI: 94.1-100%) and not evaluable in pts &lt;60yrs (p=0.017). None of the baseline features were predictive of response, additional analysis to understand impact on AEs and survival is ongoing. Among the 5 pts with progression/relapse, 4 were primary refractory. 4 pts received 2nd line (2L) therapy.79 pts are alive at data cut off, 2 deaths occurred- 1 infection-related and other unknown; both after the 1st cycle. Conclusions In this largest RWS cohort of OAs treated with NAVD we showed comparable response rates, AEs and 1-year survival outcomes to those in the pivotal S1826 trial. Notably, rates of ≥G3 AEs including infections, neuropathy and IrAEs remained low and manageable. Although survival significantly improved with NAVD compared to historical data, outcomes of OAs remained inferior compared to pts &lt;60 yrs. Our data reinforces the use of NAVD as the preferred 1L option for OAs with advanced stage cHL.

Abstract Chimeric antigen receptor T (CART) cell therapy has shown unprecedented success in the treatment of hematological malignancies. However, the immunosuppressive tumor microenvironment of both solid and liquid tumors is a major barrier for CART efficacy. Immunosuppressive myeloid cells inhibit CART efficacy. Colony-stimulating factor 1 receptor (CSF1R) promotes macrophage proliferation, survival, and anti-inflammatory response and is upregulated on myeloid cells in many cancers, making CSF1R an appealing therapeutic target. We aimed to test the interactions between CSF1R, myeloid cells, and CART response, and to study CSF1R targeting in the context of CART cell therapy. We utilized CD19-targeted CART cell therapy (CART19) in lymphoma preclinical models and thyroid-stimulating hormone receptor (TSHR)-targeting CART cell therapy (TSHR-CART) in thyroid cancer models. We first measured CSF1R expression on myeloid cells in vitro. Suppressive myeloid cells, polarized from healthy donor monocytes using an anaplastic thyroid cancer (ATC) cell line, 8505c, or mantle cell lymphoma cell line, JeKo-1, significantly upregulate CSF1R (p=0.0002) compared to media control. After polarization, myeloid cells significantly inhibit TSHR-CART and CART19 antigen-specific proliferation compared to freshly isolated monocytes (p=0.012, p&lt;0.01, respectively) indicating that suppressive myeloid cells contribute to CART failure in multiple tumor types. We then performed single cell RNA sequencing on peripheral blood taken at baseline from patients with mantle cell lymphoma treated with CART19. We found a significant increase of CSF1R on monocyte subsets in CART19 non-responders vs responders (padj=0.0037). Next, we determined the impact of CSF1R blockade on CART cell therapy in vivo. Using lymphoma models, B6 mice were engrafted with the luciferase+ CD19+ murine lymphoma cell line TBL-12 (1x106 cells i.v. 1 day after 250 mg/kg cyclophosphamide). Tumor burden was significantly reduced after 7 days of treatment with low dose CART19 (0.5x106 i.v.) + anti-mouse CSF1R antibody (16mg/kg i.p. twice weekly) vs CART19 + IgG control (p=0.0146). We then tested the impact of CSF1R blockade in mice experiencing tumor relapse. After TBL-12 engraftment, mice were treated with anti-mouse CSF1R or IgG control antibody followed two days later with high dose CART19 (1x106 i.v.) to induce remission. Mice were re-challenged with TBL-12 14 days later. Mice treated with anti-mouse CSF1R antibody showed increased tumor control and significantly higher survival (p=0.0416). Using thyroid cancer models, first we identified high macrophage infiltration in biopsy specimens of patients with ATC compared to normal thyroid tissue and benign thyroid tumors through immunohistochemistry (IHC) of patient samples (p&lt;0.01, p&lt;0.0001, respectively). To test if macrophages are associated with CART failure in ATC, NSG mice were subcutaneously engrafted with 1x106 TSHR+ THJ529 tumors, an ATC cell line derived from patient biopsy samples from the Mayo Clinic thyroid cancer biobank, followed by i.v. treatment with 1x107 TSHR-CART or untransduced T cell control (UTD). IHC staining of tumor tissue collected at experimental endpoints revealed a dose-dependent, significant infiltration of human CD3+ T cells into the tumors which inversely correlated with murine F4/80+ myeloid cell and murine YM-1+ M2 macrophage infiltration. This led us to hypothesize that myeloid cell targeting with CSF1R blockade can improve TSHR-CART efficacy. We utilized the same ATC model described above to test CSF1R targeting. When TSHR+ THJ529 tumors reached approximately 100 mm3, mice were randomized by tumor volume and treated with CSF1R inhibitor PLX5622 (600mg/kg) or vehicle control, followed by either UTD or TSHR-CART cells 5x106 i.v. Mice treated with TSHR-CART + PLX5622 showed significantly improved tumor control vs TSHR-CART + vehicle control (p&lt;0.0001) or UTD + PLX5622 (p&lt;0.0001). Together, our results highlight immunosuppressive myeloid cells which express CSF1R as a major cell type limiting CART efficacy in both solid and liquid tumors. We also identified a strategy to overcome myeloid-mediated suppression of CART cells by targeting CSF1R with antibody or small molecule inhibitors.

Abstract Background Chimeric antigen receptor T cell (CART) therapy has revolutionized treatment for hematologic malignancies. However, durable remission following anti-CD19 CART therapy (CART19) remains limited to 40–50% of patients, often due to tumor relapse and CART dysfunction (PMID:31501612). We previously demonstrated that tumor-derived extracellular vesicles (EVs) from patients with chronic lymphocytic leukemia (CLL) can directly impair CART function (PMID:33388419). In this study, we aimed to identify tumor-derived EV microRNA (miRNA) cargo associated with clinical CART failure in B cell malignancies and define how they mechanistically drive CART cell dysfunction. Methods To achieve these aims, we profiled tumor-derived EV miRNA cargo using small RNA sequencing (RNAseq) in two independent patient cohorts. Cohort 1 compared plasma-derived EVs from untreated CLL patients to those from healthy donor EVs to identify miRNAs enriched in CLL (n=23). Cohort 2 included patients with diffuse large B cell lymphoma (DLBCL) treated with axicabtagene ciloleucel (CART19, n=12). Here, plasma EV miRNAs were analyzed at baseline (pre-CART treatment) and 1-month post-CART treatment and compared between CART responders (complete remission at 6 months) and nonresponders (no response at 1 month). Enriched miRNAs from both cohorts were identified following miRNA count normalization and differential expression analysis using adjusted p values of ≤0.05. Functional studies were conducted by transfecting CART19-28ζ cells with synthetic miRNA mimics or scrambled controls. CART cells were also generated with stable overexpression of miRNA via lentiviral shRNA delivery. CART function was assessed via in vitro killing, proliferation, apoptosis assays, RNAseq, and in vivo tumor xenograft models. Results In Cohort 1, we identified several miRNAs including miR-125a to be significantly enriched in CLL-derived EVs relative to healthy controls. Similarly, in Cohort 2, miRNA-125a was also identified among the miRNAs enriched in nonresponders vs. responders to CART treatment; Notably, miR-125a was significantly enriched in nonresponders at baseline (pre-CART treatment) and 1-month post-CART treatment (p=0.0177, p=0.0196). To define the functional effects of miR-125a, we delivered synthetic mimics or stable shRNA constructs encoding miR-125a into CART cells. Delivery of miR-125a was confirmed by RT-qPCR (p&lt;0.0001 for mimic vs. scramble, p=0.0069 for shRNA vs. scramble). Here, miR-125a delivery and overexpression impaired CART cytotoxicity/killing of target tumor cells (~25% reduction, p= 0.0039), decreased antigen-specific proliferation (~47% reduction, p=0.0002), and increased apoptosis following antigen stimulation (1.8-fold increase, p=0.0002) as compared to scramble controls in vitro. We next studied how miR-125a impacts CART functions in vivo. Here, tumor-bearing mice treated with miR-125a–overexpressing CART cells (CART sh125a) exhibited accelerated tumor progression (4.1-fold increase, p=0.0019) and significantly reduced survival as compared to mice treated with scramble control CART treatment (CART shScr) (20% vs 80% survival at day 35, p=0.0064), underscoring the dramatic detrimental impact of miR-125a on therapeutic efficacy. To uncover changes in CART gene expression induced by miR-125a delivery, RNAseq was also performed across stimulated CART sh125a vs. CART shScr cells. CART sh125a cells demonstrated broad transcriptional changes, with gene set enrichment of E2F targets, G2/M checkpoint, and apoptosis pathways (FDR p&lt;0.0001, p&lt;0.0001, and p=0.006) further validating the role of miR-125a in disrupting CART cell cycle control, proliferation, and survival. Conclusion In summary, our study identifies miR-125a as a tumor-derived EV cargo that drives CART dysfunction in two separate B cell malignancies (CLL and DLBCL). miR-125a was enriched in both CLL EVs and nonresponders to CART19 therapy at baseline prior and post CART treatment. Functional studies demonstrate that miR-125a delivery and overexpression directly impair CART cytotoxicity and proliferation, increase CART apoptosis, reduce therapeutic efficacy in tumor xenograft models, and disrupt key pathways related to CART cell cycle regulation and survival. These findings position miR-125a as both a key mechanistic driver of CART failure and a potential predictive biomarker for treatment response, while highlighting it as a possible therapeutic target to improve CART outcomes in the clinic.