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BACKGROUND: Chronic aortic regurgitation (AR) is associated with significant cardiac remodeling, but the prevalence and prognostic impact of extravalvular cardiac damage remain unexplored. METHODS: Adults with moderate or greater chronic AR identified on echocardiogram between January 2008 and July 2024 were included. Exclusion criteria were acute AR, hypertrophic and infiltrative cardiomyopathies, prior cardiac surgery, and valve stenosis. Cardiac damage was classified into hierarchical stages: no cardiac damage (stage 0), left ventricular damage (stage 1), moderate or greater mitral regurgitation or left atrial enlargement or atrial fibrillation (stage 2), pulmonary hypertension or moderate or greater tricuspid regurgitation (stage 3), and significant right ventricular dysfunction (stage 4). The primary outcome was the association between cardiac damage stages and all-cause mortality under medical surveillance. RESULTS: Of 4026 patients (median age, 72 [61–80] years), 78% had moderate AR, 11% had moderate-severe, and 11% had severe AR. Cardiac damage was present in 87% of patients: 14% in stage 1, 53% in stage 2, 18% in stage 3, and 2% in stage 4. In a multivariable model, including age, sex, AR severity, and Charlson Comorbidity Index, cardiac damage stages were associated with mortality. Adjusted hazard ratios were 1.42 (95% CI, 1.04–1.96) for stage 1, 1.58 (95% CI, 1.21–2.06) for stage 2, 2.78 (95% CI, 2.10–3.67) for stage 3, and 5.34 (95% CI, 3.67–7.76) for stage 4. Adding cardiac damage staging to multivariable models improved predictive accuracy for mortality, increasing the concordance statistics from 0.73 (95% CI, 0.71–0.75) to 0.76 (95% CI, 0.74–0.77). CONCLUSIONS: Cardiac damage is present in nearly 90% of patients with moderate or greater AR and is associated with increased mortality, highlighting the need for a more comprehensive evaluation of cardiac structure and function beyond the aortic valve and left ventricle.

Abstract BTK degraders promote proteasomal degradation of BTK and can overcome resistance to covalent and noncovalent BTK inhibitors in patients with relapsed CLL. Currently the molecular basis for BTK degrader resistance is unknown. We therefore set out to understand BTK degrader resistance based on observations from the phase 1 trial of zelebrudomide (NX-2127) (NCT04830137), the first BTK degrader to enter clinical studies. Targeted 500-gene sequencing was performed on blood and/or tissue from four CLL patients treated with zelebrudomide. In one patient previously treated with chemoimmunotherapy, ibrutinib, venetoclax, and pirtobrutinib, BTK A428D was detected in the baseline blood sample with variant allele frequency (VAF) of <2%, along with BTK V416L (13%) and mutations in TP53 (60%) and SF3B1 (37%). Following daily treatment with 100mg zelebrudomide and subsequent dose escalation to 200mg, at 6 months the VAF of all four mutations increased, with BTK A428D VAF increasing to 6% in the blood and 29% in a lymph node. BTK A428D was detected at baseline but not at progression in a second patient. To evaluate the impact of BTK A428D on drug response, we transduced BTK-dependent TMD8 cells with BTK WT, C481S, L528W, and A428D, and found that BTK A428D uniquely conferred resistance to all FDA-approved BTK inhibitors (ibrutinib, acalabrutinib, zanubrutinib, pirtobrutinib) as well as three BTK degraders under clinical evaluation (zelebrudomide, bexobrutideg, BGB-16673). To model the subclonal nature of BTK A428D we conducted a competition assay in which TMD8 cells expressing GFP + BTK A428D (5%) were mixed with TMD8 cells expressing mCherry + BTK WT (95%); over 9 days the GFP + BTK A428D expanded from 5% to 88-97% with all four BTKi and all three BTK degraders. In vitro kinase assays revealed that the BTK A428D mutant protein lacks kinase activity yet facilitates calcium flux and ERK/AKT signaling upon B-cell receptor activation, suggesting a scaffolding effect similar to other kinase deficient BTK mutations. To determine whether BTK A428D affects BTK degradation, we developed a reporter that fuses the BTK kinase domain to GFP. BTK A428D showed minimal degradation following 20 hours of treatment with a titration of all three BTK degraders. Similarly, we knocked BTK A428D into the endogenous BTK locus of HBL1 cells and confirmed a lack of degradation at doses up to 1 µM of all 3 degraders. Consistent with these findings, surface plasmon resonance revealed that the FDA-approved BTK inhibitors as well as zelebrudomide, bexobrutideg, BGB-16673, and AbbVie-1 (Compound 1 from WO 2023183811) are unable to bind to BTK A428D. Additionally, an in-cell NanoBRET assay demonstrated that zelebrudomide was unable to mediate the interaction between cereblon and BTK A428D. Strikingly, NanoBRET also demonstrated that a panel of promiscuous kinase-binding compounds was unable to bind to BTK A428D. The lack of binding of both selective and promiscuous kinase binders to BTK A428D led us to speculate that the mutation disrupted the ATP binding pocket to an unusual degree. We therefore solved the crystal structure of apo BTK A428D and found that, in addition to its predicted steric clash with ligand binding in the hinge region, the mutation led the protein to crystallize with its activation loop occupying the catalytic cleft, rendering it inaccessible. This is the first apo BTK structure observed in this autoinhibited conformation, and explains the observed binding profile. We hypothesized that the addition of a second targeted agent such as venetoclax might mitigate expansion of the A428D subclone. To test this, we introduced the BTK A428D mutation into the endogenous BTK gene in 3% of TMD8 cells and then exposed them to 0.1µM of zelebrudomide, bexobrutideg, or BGB-16673 +/- venetoclax 0.1µM. Combining the BTK degraders with venetoclax slowed the emergence of the BTK A428D resistant population and, in the case of zelebrudomide, eradicated both the wild-type and A428D clones. In summary, we identified and validated BTK A428D as a clinically relevant acquired pan-resistance mutation that confers resistance by blocking access to the ATP binding pocket. This mechanism differs from other kinase dead BTK mutations in which the kinase's enzymatic pocket remained accessible.These data also provide rationale for combining BTK degraders with BCL2 inhibitors, particularly in patients with BTK A428D mutations, or high-risk mutations such as in TP53.

Abstract Introduction: The real-world outcomes in patients (pts) with PCALCL in the era of targeted therapies like Brentuximab Vedotin (BV) is not well defined due to lack of large multicenter studies. We conducted a multicenter retrospective analysis (RWA) to assess patient and disease characteristics, treatment patterns, survival outcomes and impact of novel therapies in this rare type of cutaneous T cell lymphoma (CTCL). Methods: The analysis included 167 adult (≥18 years) patients (pts) with PCALCL across 9 academic institutions in the United States diagnosed between 01/2012 to 06/2022. The study was approved by the Institutional Review Boards at the respective sites. Demographic and disease factors were summarized using descriptive statistics. Overall survival (OS) and relapse-free survival (RFS) were estimated using Kaplan-Meier method and compared via log rank tests. Prognostic models included factors such as age, sex, race, performance status (PS), disease stage, type of initial lesion, presence of B symptoms, previous history of lymphomatoid papulosis and prior transplant. Prognostic factors for survival were assessed using both univariable and multivariable Cox proportional hazard models. Results: The median age at diagnosis was 61 (range 18-93) years. The majority of pts were male (55%) and white (82%), with good PS as indicated by an ECOG 0-1 (71%). The initial skin presentation consisted of tumors in 62% of the pts, while 34% presented with plaques or patches. Notably, no pts presented with erythroderma. Most pts underwent PET scan for staging at initial diagnosis (83%) with the majority having early-stage (IA-IIA) disease (86%). Furthermore, palpable lymph nodes (11%) and the presence of B symptoms (4%) were rare at diagnosis, and no pts had blood involvement. The most common sites of involvement were extremities (33%) followed by the head and neck (H&N) and trunk (31% each). Immunophenotyping revealed CD4 positivity in 59% of pts and CD8 positivity in 25%. The T cell receptor (TCR) rearrangement was positive in 28% of pts, though it was not completed in the majority of cases (72%). Most common initial treatments included localized radiation (61%) and surgical excision (19%). A small subset of pts received frontline systemic chemotherapy regimens such as cytotoxic chemotherapy (11%), BV (8%) and oral methotrexate (MTX) (8%). Approximately 7% of the pts had a stem cell transplant. Overall response rate (ORR) for radiation, oral MTX, BV and cytotoxic chemotherapy were 78% (CR:78% 74/100), 42% (CR:63% 6/12) and 39% (CR:67% 6/12), 89% (CR: 88% 15/18) respectively. At a median follow-up of 3.8 years (range 0.04-10.23), the median RFS and OS were 2.7 years (95% CI:1.86, 3.43) and 12 years (95% CI:10.6- NA) respectively. The estimated 3- and 5-year RFS are 46% (95% CI:0.38, 0.55) and 37% (95% CI:0.28, 0.46) respectively. The estimated 3- and 5-year OS were 89% (95% CI:0.82, 0.93) and 82% (95% CI:0.73, 0.88) respectively. At the time of the last follow-up, 79% were alive, while 21% were deceased. The cause of death (COD) was unknown in 50% of the cases and only 10% (3/of deaths were attributed to lymphoma. Other known CODs included infection (20%) and second malignancies 7%. On univariate analysis (UVA), age (p=.007), female sex (p=.04), ECOG PS 1-2 compared to 0 (p=.007) and prior transplant (p=.009) predicted for worse RFS. On multivariate analysis (MVA), only ECOG PS 1-2 (HR 2.31, 95 CI:1.06, 1.18, p=.009) and prior transplant (HR 5.38, 95 CI:2.30, 12.57, p=.0001) had a significant impact on RFS. Age and presence of B symptoms were strong predictors of OS on both UVA (age p=<.0001; B symptoms p=<.0001) and MVA (age: HR 1.12, 95 CI:1.06, 1.18, p=<.0001; B symptoms: HR 16.48, 95 CI: 3.69, 73.60, p=.0002). However, the impact of B symptoms should be interpreted with caution as only 4% of pts presented with this at baseline. On UVA, each one-year increase in age was associated with an 8.5% rise in the risk of death. ECOG PS 1-2 was associated with worse OS on univariate analysis (HR 2.62, 95% CI 0.99, 6.93, p=.05), but was not significant on MVA (HR 1.05, 95% CI 0.368, 2.974, p=.93). Conclusions: In this large RWA of PCALCL, excellent long-term survival was observed with predominantly skin directed frontline therapies. The use of systemic treatments, including BV, was infrequent as first line therapy. Older age and poor PS were significant predictors for reduced survival.

Abstract Introduction: Primary central nervous system T-cell lymphoma (PCNSTL) is a rare form of PCNSL, comprising 2–8% of cases. Prognostic factors remain undefined, and no standard treatment protocol currently exists. Prior studies have been limited by small sample sizes, incomplete molecular profiling, and poor representation of novel treatment modalities. In this study, we aimed to identify clinicopathologic factors associated with patient (pt) outcomes and delineate the spectrum of treatment regimens used to inform future clinical practice. Methods A multicenter retrospective study was conducted across 15 North American academic institutions. Pts aged ≥18 years with biopsy-confirmed PCNSTL between 2009 and 2025 with no evidence of systemic disease were included. Cases with CNS relapse of systemic T-cell lymphoma were excluded. Baseline characteristics were analyzed using independent t-tests, Fisher's exact tests, or Pearson's chi-square tests. Primary endpoints were overall survival (OS) and progression-free survival (PFS), evaluated by Kaplan–Meier, log-rank tests, and Cox regression. Results: Forty-two pts met inclusion criteria. Median age was 57 (range 19–77), 69% were male, and 79% were white. Most (69%) had ECOG 0–1. No patients had HIV, hepatitis B or C, or a history of solid organ transplant. LDH was elevated at diagnosis in 38%, and 24% had B-symptoms. Mean absolute lymphocyte count at diagnosis was 1.82/µL. The most common histologic subtypes were PTCL-NOS (76%), followed by ALK-negative ALCL (12%) and γδ T-cell lymphoma (5%). All patients had parenchymal brain lesions with 57% having multifocal disease. Additionally, CSF involvement was seen in 21%, vitreoretinal involvement in 3%, and deep brain involvement in 34%. Next-generation sequencing was performed in seven pts (17%), with disease-associated variants identified in three cases. Among these, two pts had mutations in TP53, and one had a mutation in DNMT3A. Cytogenetics were obtained in 7 pts with only one exhibiting a complex karyotype. Only one pt was EBV positive by EBER-ISH. Overall, 79% received HD-MTX-based therapy. First-line treatments were mainly HD-MTX alone (38%), HD-MTX + temozolomide (17%), or vincristine + procarbazine (12%). No patients were treated on clinical trials. Median treatment duration was 78 days and median number of treatment cycles was 4 (range 1–9 cycles). One patient received radiation alone; 5% received radiation with systemic therapy. A steroid pre-phase was used in 60%, with 44% exhibiting a clinical response. Overall response rate to first-line treatment was 63% (13 CR, 12 PR). Imaging alone was used in determining response in all patients. Repeated biopsy was not performed. Twelve patients (29%) underwent consolidative autologous transplant, most commonly with thiotepa/carmustine (TT/BCNU, 69%) or BEAM conditioning (25%). Median duration of follow-up was 10.4 months. Sixty-two percent of pts progressed during the study period, with 7% experiencing extra-CNS relapse. Median PFS was 8.2 months. Improved PFS was associated with >3 cycles of therapy (p=0.03) and transplant with TT/BCNU (p=0.0004). At last follow-up, 43% were in remission and 52% were deceased, mostly due to disease progression (77%). Median OS was 17.6 months. One- and two-year OS rates were 58% and 42%, respectively. OS was associated with Nottingham/Barcelona score <2 (p=0.02), >3 treatment cycles (p=0.0008), response to first-line therapy (p=0.0007), and TT/BCNU-based transplant (p=0.0001). IELSG, Taipei, and MSKCC risk scores were not significantly associated with survival, though IELSG approached significance (p=0.09). Discussion: This study is among the largest cohorts of PCNSTL pts compiled to date. PCNSTL remains rare and heterogenous. Treatment across centers largely mirrors management of B-cell PCNSL with high utilization of HD-MTX regimens and TT/BCNU conditioning autologous transplant. Survival outcomes within our cohort are consistent with those previously reported within the literature. Receipt of >3 cycles of therapy, TT/BCNU conditioning and Nottingham/Barcelona scores were associated with longer survival within our cohort. Limitations of our study include its retrospective design and heterogeneity within pt disease characteristics, treatments utilized and disease assessment intervals. Further exploration into pathophysiology and optimal management of this unique entity is needed.

Abstract Introduction: T-PLL is a rare, aggressive leukemia with poor prognosis and limited therapies. Previous studies on T-PLL patients receiving an allogeneic stem cell transplant (alloSCT) are limited by small numbers with limited data on disease and transplant characteristics. Further, recent data from our large national cohort of patients demonstrated significant survival difference between TCL1A+ and TCL1A- T-PLL, and CD8+ T-PLL vs CD8- T-PLL. In this large multi-center series, utilizing comprehensive disease subtype and alloSCT clinical data, we evaluated prognostic and survival therapeutic outcomes in T-PLL patients that had an alloSCT with a particular focus on T-PLL disease subtypes. Methods: We retrospectively evaluated 572 diagnosed with T-PLL at 21 academic cancer centers throughout the USA between 2000-2023, of which we performed a further evaluation on the169 that proceeded with alloSCT. Overall survival (OS) and progression-free survival (PFS) were assessed using Kaplan-Meier methods and Cox proportional hazard models. Results: Among n=169 alloSCT recipients with T-PLL, the median follow-up time was 20.9 months post-alloSCT (range: 0.2-182.9), the median age at transplant was 59 years (range: 35-77) and 52% were male. In evaluated patients (n=109), TCL1A was positive by cytogenetics or FISH in 69%. As our recent analysis demonstrated significant differences in survival among specific subtypes of T-PLL, we evaluated outcomes in patients with CD4+CD8- T-PLL (n=90, 53%), CD4-CD8+ (n=17, 10%) T-PLL, and CD4+CD8+ T-PLL (n=52, 31%). 53% (87/164) had known nodal involvement at diagnosis identified by PET or CT scan and 45% (43/96) of known patients had minimal residual disease (MRD) at the time of transplant [defined as <5% T-PLL in marrow by flow, or +cytogenetics (e.g. TCL1A)] prior to alloSCT. At the time of alloSCT, 136 (80%) patients were in CR and 23 (14%) patients were in PR. Forty-nine (30%) had a myeloablative (MAC)conditioning regimen and 114 (70%) had a reduced intensity chemotherapy (RIC) conditioning regimen. Eighty (49%) patients had TBI as part of their regimen. The most common regimens were fludarabine (flu)/melphalan based regimens (n=44; 26.0%), flu/cyclophosphamide (cy) based regimens (n=33; 19.5%), flu/busulfan based regimens (n=22; 13.0%), flu/total body irradiation (TBI) (n=8; 4.7%), and cy/TBI (n=4; 2.4%). Across the whole cohort, the median OS and PFS post-alloSCT was 32.6 months (95% CI: 21.0-41.9) and 20.8 months (95% CI: 14.4-30.5) months while the 1-year cumulative incidences (CI) of NRM and relapse were 17% and 20%, respectively. The incidences of grade II-IV acute GVHD and cGVHD were 19% and 23%. There was no difference between patients with myeloablative conditioning (MAC) (n=49, 29%) when compared to patients that received reduced intensity conditioning (RIC) (n=114, 67%) in OS (33.1 vs 29.2; p=0.68) and PFS (20.2 vs 20.8; p=0.97). Patients that were MRD+ (n=31) had worse OS (22.2 vs 48.6; p=0.1) and PFS (14.1 vs 32.5; p=0.04) and higher rates of relapse (1-year relapse 20% vs 8%; p=0.08) than patients that were MRD- (n=50). PFS was improved in those who received alloSCT though only trended towards significance due to low numbers (HR 0.76, p=0.09). In subtype analysis, TCL1A+ T-PLL had significantly worse outcomes compared to TCL1A negative T-PLL. TCL1A+ disease had significantly worse OS (21.6 vs 63.1; p=0.01) and PFS (12.4 vs 50.7; p=0.01) compared to TCL1A-. Additionally, in TCL1A+ disease CI of NRM (24% vs 3%; p=0.02) and relapse (25% vs 12%; p=0.86) was higher vs TCL1A- PLL. CD4+CD8-, CD4-CD8+, and CD4+CD8+ disease had no difference in survival via either OS (28.0 vs 34.4 vs 21.0; p=0.17) or PFS (29.4 vs 23.5 vs 13.6; p=0.09) as well as no difference 1-year CI of NRM ( 11.6 vs 23.5 vs 26.2; p=0.35) and relapse (18.5 vs 23.5 vs 20.0; p=0.67).Conclusions: AlloSCT significantly improved outcomes for patients with T-PLL compared to those who did not proceed to alloSCT and remains he only curative therapy for those with T-PLL. OS, PFS, and CI relapse were significantly worse for patients with TCL1A+ subtype of T-PLL, or those with MRD positivity or PR prior to alloSCT. Novel strategies to decrease relapse such as post-alloSCT maintenance therapy to improve outcomes are urgently needed in these patients.

Abstract Background Patients with Crohn disease (CD) face an elevated risk of developing small bowel adenocarcinoma (SBA), a malignancy characterized by late-stage diagnosis and poor prognosis. In this study we aimed to characterize surgical management and oncologic outcomes for CD-associated SBA. Methods A retrospective review was conducted across 3 tertiary IBD centers, analyzing 99 patients with CD who underwent surgery for SBA between 1992 and 2025. Data included patient demographics, CD history, surgical details, and oncologic outcomes. Results The median time from CD diagnosis to SBA was 25 years. The SBA diagnosis was incidental in 74.8% of cases, discovered during surgery for other complications. Tumors were predominantly located in the ileum (80.8%) and showed aggressive features: 56.6% were poorly differentiated (grade 3), and 85.9% were pathologically advanced (T3/T4 on TNM staging). Nodal involvement was present in 45.5% of patients, and 18.2% had distant metastases at diagnosis. A complete (R0) resection was achieved in 90.9% of surgeries, with a 30-day morbidity rate of 26.3%. After a median follow-up of 36 months, the distant recurrence rate was 28.3%, and overall mortality was 27.3% (18.2% cancer related). Conclusion In patients with long-standing CD, SBA is typically an incidental diagnosis made at an advanced stage. While high rates of complete surgical resection are possible, the prognosis remains guarded due to aggressive tumor biology and high recurrence rates. These findings highlight a critical need for improved risk stratification to guide surveillance and for the development of evidence-based adjuvant treatment strategies.

Abstract Description Glioblastoma (GBM), the most common and malignant primary brain tumor, exhibits profound immune suppression, hindering immunotherapy efficacy. GBM-derived extracellular vesicles (EVs) play a major role through the immunosuppressive polarization of myeloid cells. Inhibition of EV-myeloid cell interactions thus represents a novel target to mitigate GBM-mediated immune suppression. However, there are multiple mechanisms of EV-target interaction, and downstream pathways of GBM-EV signaling are poorly understood. We explored two pharmacological agents targeting different mechanisms of EV uptake: Methyl-B-cyclodextrin (MBCD), which disrupts lipid rafts, and cytochalasin D, which inhibits actin polymerization. Our results showed immunosuppressive myeloid cell (CD11b+/ CD15-/ HLA-DRlow/ CD14high) populations increased upon GBM-EV treatment. Following cytochalasin D treatment, fewer immunosuppressive myeloid cells were observed (7.40%±1.01 vs. untreated 9.66%±2.86), with rescuing T cell proliferation. Conversely, MBCD treatment increased immunosuppressive myeloid cell levels (10.42%±2.38 vs. untreated 8.87%±3.97) without impacting T cell proliferation. This study demonstrates the feasibility of pharmacologically targeting EV-myeloid cell interactions to rescue tumor mediated immune suppression by inhibiting actin-dependent endocytosis with cytochalasin D. The converse results using MBCD treatment indicate differential importance of different EV uptake pathways in monocyte regulation. Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Abstract Description Glioblastoma (GBM), the most common and malignant primary brain tumor, exhibits profound immune suppression, hindering immunotherapy efficacy. GBM-derived extracellular vesicles (EVs) play a major role through the immunosuppressive polarization of myeloid cells. Inhibition of EV-myeloid cell interactions thus represents a novel target to mitigate GBM-mediated immune suppression. However, there are multiple mechanisms of EV-target interaction, and downstream pathways of GBM-EV signaling are poorly understood. We explored two pharmacological agents targeting different mechanisms of EV uptake: Methyl-B-cyclodextrin (MBCD), which disrupts lipid rafts, and cytochalasin D, which inhibits actin polymerization. Our results showed immunosuppressive myeloid cell (CD11b+/ CD15-/ HLA-DRlow/ CD14high) populations increased upon GBM-EV treatment. Following cytochalasin D treatment, fewer immunosuppressive myeloid cells were observed (7.40%±1.01 vs. untreated 9.66%±2.86), with rescuing T cell proliferation. Conversely, MBCD treatment increased immunosuppressive myeloid cell levels (10.42%±2.38 vs. untreated 8.87%±3.97) without impacting T cell proliferation. This study demonstrates the feasibility of pharmacologically targeting EV-myeloid cell interactions to rescue tumor-mediated immune suppression by inhibiting actin-dependent endocytosis with cytochalasin D. The converse results using MBCD treatment indicate differential importance of different EV uptake pathways in monocyte regulation. Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Abstract Description Glioblastoma (GBM), the most common and deadly primary brain tumor in adults, is associated with profound local and systemic immune suppression. Increasing evidence points to tumor-derived extracellular vesicles (EVs) as key mediators of this immunosuppression. In surveying the tumor-immune microenvironment in samples of ultrasonic aspirate collected during surgical resection of GBM (n = 12), we identified several key immunomodulatory markers expressed across a range of immune cells in the tumor microenvironment. Particularly, we found TIGIT, classically understood as a T cell inhibitory protein, expressed across a range of myeloid cell populations, including in myeloid-derived suppressor cells (MDSCs, 46.84±16.78% of total monocytic MDSCs). Co-culture of healthy donor monocytes (n = 10) with patient-derived EVs replicated similar effects (control 11.69±1.87 vs EV treated 23.32±2.0). Furthermore, Induced MDSCs significantly inhibit T cell proliferation (30.65±5.97% proliferation, v/s control 86.47±2.94, p = 0.0001), concomitant with a surge in Th2 immune responses via TIGIT+ suppressive monocytes. Targeted TIGIT inhibition restored T cell proliferation (64.13±1.327% v/s non-inhibited, 30.65±5.97%; p = 0.02) and protective immune response, confirming a pivotal role of TIGIT in immune suppressive GBM microenvironment. Furthermore, TIGIT inhibition may unmask NLRP3 function, potentially contributing to immune rescue. Funding Sources Neurosurgery Research& Education Foundation, K12 grant Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Abstract Statistical learning (SL) is a powerful mechanism that supports the ability to extract regularities from environmental input. Yet, its neural underpinnings are not well understood. Previous EEG studies of SL have found that the brain tracks regularities by synchronizing its activity with the presented stimuli—a phenomenon known as neural entrainment. However, EEG lacks the spatial resolution to unveil the specific brain regions where this process takes place. In our study, 18 patients with drug-resistant epilepsy who were implanted with intracranial electrodes for presurgical investigation listened to a continuous speech stream containing embedded trisyllabic words. Neural entrainment was measured at the syllable and word frequencies, with the latter providing an online index of learning. SL was further assessed through both explicit and implicit behavioral measures. Behaviorally, we found evidence of learning at the group level in both tasks. At the neural level, our analyses revealed three temporal tuning profiles: 25% of contacts showed entrainment at the syllable frequency, 11% of contacts showed entrainment at both the word and syllable frequencies, and 4% showed entrainment only to the word frequency. Word entrainment, indicating sensitivity to word structures, was most commonly found in auditory and language-related regions, including insula, middle temporal gyrus, superior temporal gyrus, and supramarginal gyrus. In contrast, evidence for neural entrainment in the hippocampus was weak. Overall, these results support the idea that speech-based SL is largely supported by modality-specific brain regions.