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Background: Acute ischemic stroke (AIS) from distal medium vessel occlusion (DMVO) presents unique treatment challenges. Mechanical thrombectomy (MT) is emerging as a viable option for these patients, yet the role of pre-stroke aspirin treatment is unclear. This study evaluates the impact of pre-stroke low-dose aspirin on outcomes in DMVO patients undergoing MT. Methods: We conducted a multinational, multicenter, propensity score-weighted analysis within the Multicenter Analysis of primary Distal medium vessel occlusions: effect of Mechanical Thrombectomy (MAD-MT) registry. Patients with AIS due to DMVO, treated with MT, were included. We compared outcomes between patients on pre-stroke low-dose aspirin (75–100 mg) and those not on antiplatelet therapy. The primary outcome was functional independence at 90 days (modified Rankin Scale (mRS), 0–2). Secondary outcomes included excellent functional outcome at 90 days (mRS, 0–1), mortality, and day 1 post-MT National Institutes of Health Stroke Scale (NIHSS) score. Safety outcomes focused on hemorrhagic complications, including symptomatic intracerebral hemorrhage (sICH). Results: Among 1354 patients, 150 were on pre-stroke low-dose aspirin. After applying inverse probability of treatment weighting (IPTW), aspirin use was associated with significantly better functional outcomes (mRS, 0–2: odds ratio (OR) = 1.89, 95% confidence interval (CI) = 1.14 to 3.12) and lower 90-day mortality (OR = 0.56, 95% CI = 0.32 to 1.00). The aspirin group had lower NIHSS scores on day 1 (β = −1.5, 95% CI = −2.8 to −0.27). The sICH rate was not significantly different between the groups (OR = 0.92, 95% CI = 0.60 to 1.43). Conclusions: Pre-stroke low-dose aspirin was associated with improved functional outcomes and reduced mortality in patients with DMVO undergoing MT, without a significant increase in sICH. These findings suggest that low-dose aspirin may be safe and associated with more frequent excellent outcomes for this patient population. Further prospective studies are needed to validate these results and assess long-term outcomes.

727 Background: PARP inhibition (PARPi) is a standard maintenance therapy for patients (pts) with germline BRCA1/2 mutations in pancreatic cancer. Combination of PARPi therapy and immunotherapy has potential to increase efficacy and may offer benefit beyond germline BRCA1/2 . Methods: We performed a multisite single-arm phase 2 study using the highly potent PARPi niraparib with anti-PD1 drug dostarlimab in pts with germline or somatic HRD mutations in BRCA1/2, PALB2, RAD51C/D, or BARD1 . Pts were required to have metastasis, progressed on ≥1 regimen, and prior platinum-exposure unless refused/intolerant. Pts were treated with niraparib 200 mg orally once daily continuously. Dostarlimab 500 mg was administered IV every 3 weeks for 4 cycles, then 1000 mg IV every 6 weeks. The primary endpoint was disease control rate (DCR) at 12 weeks (DCR12) using iRECIST criteria. At least 8 pts with DCR12 in the first 19 eligible pts (41%) would be considered promising for further trials. Results: 22 pts were enrolled from Dec 2020 to Oct 2023. Two pts withdrew prior to receiving therapy, and 2 were later found to be ineligible, leaving 18 eligible pts for final analyses. Median age was 63.0 yrs, 39% male, 94% non-Hispanic white, 1 black (6%). 17 pts were platinum exposed, 7 were platinum-refractory, and 5 had previously progressed on PARPi maintenance. Mutation distribution was: BRCA2 13/18 (72%), BRCA1 4/18 (22%), BARD1 2/18 (11%). One pt had both BRCA1 (somatic) and BRCA2 (germline) mutations. Germline mutations were identified in 14/18 (78%). DCR12 was achieved in 5/18 (27.8%), so the primary endpoint (>41%) was not met. Pts received a median 2 cycles (range 1-8) of niraparib + dostarlimab. No clinical factors were significantly associated with improved DCR12 (all p > 0.05) in subgroup analyses, but we did observe the following statistically nonsignificant associations. Pts who were platinum-refractory had a lower DCR12 compared to those not (14.3% vs. 36.4%). Counterintuitively, PARPi exposed/refractory pts had a higher DCR12 than non-exposed/non-refractory (50 vs 17% exposed/nonexposed and 40% vs 23% refractory/nonrefractory). Pts with germline mutations had a higher DCR12 compared to those without (38.5% vs. 0%). Non- BRCA2 mutations had a higher DCR12 than those with BRCA2 mutations (50% vs.17%), with highest DCR12 rates among BRCA1 patients (67%). Tolerability was in line with similar combinations, with 60% non-hematologic Gr3 or higher, including fatigue (15%), AST increase (10%), nausea/vomiting (10%), sepsis (10%). Two grade 5 events were not attributed to treatment. Conclusions: PARPi plus anti-PD1 checkpoint inhibition was not sufficiently active as later line therapy in metastatic pancreatic cancer for the majority of patients with HRD mutations. Additional molecular analyses to elucidate predictive markers of sensitivity/resistance are ongoing. Clinical trial information: NCT04493060 .

10 Background: Cell-free circulating tumor tissue modified viral DNA (ctDNA) has been used as a biomarker to detect recurrence for anal squamous cell carcinoma (ASCC). However, its value in informing treatment modification during definitive chemoradiation (CRT) has yet to be explored. We evaluated ctDNA response during and at completion of definitive CRT to establish patterns of disease response and inform future studies to personalize treatment. Methods: From 11/2022 to 6/2024, 13 consecutive patients with biopsy proven, non-metastatic ASCC received definitive CRT and had ctDNA testing using a commercially available droplet digital quantitative PCR assay. ctDNA testing was done at baseline (pre-CRT), week 4 of CRT, and/or end of CRT, 1-3 months post-CRT, and every 6 months thereafter. CRT included concurrent 5FU/MMC (or capecitabine/MMC) and radiotherapy according to RTOG 0529. Treatment response assessment included: physical exam, anoscopy, and imaging with PET/CT, CT C/A/P +/- MRI abdomen and pelvis. Results: 13 patients had ctDNA testing and 11 patients had HPV-positive ASCC and tested positive for ctDNA. The 11 patients with detectable baseline ctDNA were included in this analysis. The median age at diagnosis was 63 years old. Staging included: 1- Stage IIA, 7- Stage IIB, 1- Stage IIIA, 2- Stage IIIC. 1 patient was cN0, while 11 were cN1. With a median follow-up from completion of CRT of 13 months, 4 patients have persistent or recurrent disease: 2 with distant metastases, 1 with persistent local disease (1 month post-CRT), and 1 with local and distant recurrence. Baseline value of ctDNA did not correlate to stage at diagnosis, rate of clearance during CRT, or likelihood of recurrence. 5 of 11 patients cleared ctDNA by week 4 of CRT. Of 5 patients who cleared ctDNA by week 4 of CRT, 4 remain NED and 1 developed distant metastases. Of 6 patients with persistent ctDNA at week 4 of CRT, 3 have persistent or recurrent disease- 1 local persistence 1 month post-CRT, 1 local and distant recurrence 6 months post-CRT, and 1 with distant recurrence 12 months post- CRT. Among 6 patients who cleared ctDNA by the final week of CRT, 1 patient developed recurrent disease. Among the 4 patients in the series with residual/recurrent disease, 3 of them had not cleared ctDNA by the end of CRT. Of 10 patients with ctDNA testing at 1 month post-CRT, 8 had no detectable ctDNA. 2 patients with persistent (1) or recurrent (1) ctDNA at 1 month post-CRT developed disease recurrence- 1 with distant recurrence and 1 with local and distant recurrence. Conclusions: ctDNA assessment during CRT may provide insight into disease response that can predict patterns of failure and facilitate personalized therapy- treatment intensification, deintensification, or additional testing to detect early metastatic disease. Larger studies and clinical validation are needed.

163 Background: CRC with PM has a poor prognosis and limited treatment options. Immunotherapy has shown promise in improving outcomes for patients with microsatellite instability-high (MSI-H), mismatch repair-deficient (dMMR), and high tumor mutational burden (TMB-H) tumors. However the peritoneal niche has a unique microenvironment, which can influence the effectiveness of immune check point inhibitors (ICIs). We assessed the impact of ICI on progression-free survival (PFS) and overall survival (OS) in CRC patients (pts) and PM, considering key clinical and molecular characteristics. Methods: A retrospective review aiming to identify CRC pts with MSI-H/dMMR and PM treated with immunotherapy between 2015 and 2023 was performed. Data collected included pt demographics, tumor characteristics, and treatment details. Responses were evaluated using RECIST v1.1 criteria. Results: 37 pts were included, 9 (24%) had Lynch syndrome. The median age of diagnosis was 61 years and most pts were females (65%). Most pts had MSI-H/dMMR tumors, while one pt was treated based on ultra-hypermutated phenotype (TMB 202) and POLE mutation. Among those with available TMB data, the median TMB was 52 mutations/Mb (0-202). Common mutations were PMS2 (51%), MLH1 (38%), MSH6 (16.2%), and MSH2 (16.2%). Right-sided tumors were in 54%, mucinous histology in 62%, and ascites in 54%. Pts received a median of 11 cycles of ICI (2-52). Pembrolizumab was the most frequently used ICI (78%), while Nivolumab was used either alone (11%) or in combination with Ipilimumab (11%). Median PFS in our cohort was 7.8 months and median OS was 29.9 months. The disease control rate (DCR) was 81%, with an objective response rate (ORR) of 51.3% (9 complete responses, 12 partial responses). At the time of data collection, 30% of pts were off systemic therapy and 5-FU-based chemotherapy combined with a biologic agent was the most common subsequent treatment in 32% who had PD. Univariate analysis showed no significant differences in PFS or OS based on tumor sidedness, isolated PM, liver metastases, mucinous vs. non mucinous histology or BRAF / RAS status (WT vs mutant). Malignant ascites was associated with worse OS(HR 0.3; p= 0.03). Conclusions: Treatment with ICIs in pts with MSI-H/dMMR and/or TMB-H CRC and PM improved disease control in CRC pts with PM, however, as compared to historical controls for patients with MSI-H/d-MMR disease treated with ICI, this group showed less favorable outcomes. Malignant ascites was associated with poorer overall survival. Further research of the immune response and tumor microenvironment in the peritoneal cavity is warranted.

Abstract Background We previously identified circulating and MRI biomarkers associated with the surgical management of Crohn’s disease (CD). Here we tested associations between these biomarkers and ileal resection inflammation and collagen content. Methods Fifty CD patients undergoing ileal resection were prospectively enrolled at 4 centers. Circulating CD64, extracellular matrix protein 1 (ECM1), GM-CSF autoantibodies (GM-CSF Ab), and fecal calprotectin were measured by ELISA. Ileal 3-dimensional magnetization transfer ratio (3D MTR), modified Look-Locker inversion recovery (MOLLI) T1 relaxation, diffusion-weighted intravoxel incoherent motion (IVIM), and the simplified magnetic resonance index of activity (sMaRIA) were measured by MRI. Ileal resection specimen acute inflammation was graded, and collagen content was measured quantitatively using second harmonic imaging microscopy. Associations between biomarkers and ileal collagen content were tested. Results Median (interquartile range [IQR]) age was 19.5 (16-33) years. We observed an inverse relationship between ileal acute inflammation and collagen content (r = −0.39 [95% confidence interval {CI}: −0.61, −0.10], P = .008). Most patients (33 [66%]) received biologics, with no variation in collagen content with treatment exposures. In the univariate analysis, CD64, GM-CSF Ab, fecal calprotectin, and sMaRIA were positively associated with acute inflammation and negatively associated with collagen content (P < .1). The multivariable model for ileal collagen content (R2 = 0.31 [95% CI: 0.11, 0.52]) included log CD64 (β = −.27; P = .19), log ECM1 (β = .47; P = .06), log GM-CSF Ab (β = −.15; P = .01), IVIM f (β = .29, P = .10), and IVIM D* (β = 1.69, P = .13). Conclusions Clinically available and exploratory circulating and MRI biomarkers are associated with the degree of inflammation versus fibrosis in CD ileal resections. With further validation, these biomarkers may be used to guide medical and surgical decision-making for refractory CD.

Background Current randomized controlled trials are investigating the efficacy and safety of mechanical thrombectomy (MT) in patients with medium vessel occlusion (MeVO) stroke. Whether best medical management (MM) is more efficient than unsuccessful vessel recanalization during MT remains unknown. Methods This was a retrospective cohort study using data from 37 academic centers across North America, Asia, and Europe between September 2017 and July 2021. Only patients with occlusion of the distal branches (M2 and M3) of the middle cerebral artery territory were included. Unsuccessful MT was defined as a modified Thrombolysis in Cerebral Infarction score of 0–2a. Propensity score matching was used to control for confounders. The primary outcome was functional independence, defined as a modified Rankin Scale (mRS) score of 0–2 at 90 days after treatment. Multivariable regression analysis was used to assess factors associated with the primary outcome. Results Of 2903 patients screened for eligibility, 532 patients were analyzed (266 per group) after propensity score matching. The MM group had superior functional outcomes, with 32% achieving mRS 0–1 at 90 days compared with 21% in the MT group (P=0.011). Patients in the MM group also had significantly lower rates of symptomatic intracranial hemorrhage (sICH) (3.4% vs 16%, P<0.001) and any hemorrhage (18% vs 48%, P<0.001). On multivariable regression, unsuccessful MT was associated with reduced odds of functional independence (OR 0.50, 95% CI 0.29 to 0.85, P=0.011) and increased odds of sICH (OR 4.32, 95% CI 1.84 to 10.10, P<0.001). Mortality rates were similar between groups (27% in MM vs 29% in MT, P=0.73). Conclusion Unsuccessful MT for MeVO was linked to worse outcomes than best MM. These findings highlight the risks of prolonged attempts and emphasize the importance of efficient procedural decision-making to reduce complications and improve patient outcomes.

ABSTRACT Introduction Despite the emergence of drugs to treat irritable bowel syndrome (IBS), improving abdominal pain can still be challenging. α 2 δ ligands, such as gabapentin and pregabalin, are sometimes used off‐label to tackle this problem. However, evidence for efficacy is limited, and no large‐scale studies have been published. Aim To study the efficacy of the α 2 δ ligand PD‐217,014 in IBS. Methods This multi‐centre, double‐blind, randomised, placebo‐controlled, parallel group study randomised participants with Rome II‐defined IBS to 150 or 300 mg b.d. of PD‐217,014 or placebo b.d. for 4 weeks. The primary efficacy endpoint was responder, defined as having adequate relief of abdominal pain/discomfort for ≥ 50% of the active treatment period. Key secondary endpoints were change from baseline in abdominal pain, bloating, stool frequency/consistency, and global assessment of IBS symptoms. Results We randomised 330 participants [aged 19–73 years; 209 (65%) female] satisfying Rome II criteria, 322 (98%) were treated, and of whom 271 (84%) completed the study. In this study, 321 satisfied Rome IV criteria. Neither dose of PD‐217,014 improved the percentage of participants reporting adequate relief of abdominal pain/discomfort compared with placebo, either using the Rome II‐defined total cohort or Rome II and IV IBS bowel habit sub‐types. There were similar observations for secondary endpoints, and no association between abdominal pain or anxiety levels at baseline with participant improvement. PD‐217,014 was generally well tolerated. Conclusion This first large, dose‐ranging trial examining the efficacy of PD‐217,014 showed no significant efficacy in participants with IBS or bowel habit sub‐types, irrespective of their pain and anxiety levels.

Dermatofibrosarcoma protuberans (DFSP) is a rare cutaneous soft tissue sarcoma and affects an estimated 1,500 people annually in the United States. DFSP frequently exhibits extensive local infiltration. Initial treatment is through surgical excision, and care should be taken to ensure that negative margins are achieved to minimize recurrence. Although DFSP has a reported high rate of recurrence, metastasis is more uncommon. Fibrosarcomatous DFSP is an aggressive variant with an increased risk for local recurrence and metastasis. If achieving negative margins or resection is not feasible, radiation therapy or systemic treatment are options that may be considered by a multidisciplinary team. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) outline recommended treatment options available for DFSP.

Study Design Narrative Review. Objective The management of spinal tumors requires a multi-disciplinary approach including surgery, radiation, and systemic therapy. Surgical approaches typically require posterior segmental instrumentation to maintain long-term spinal stability. Carbon fiber reinforced pedicle screws (CFRP) are increasingly used in the oncologic setting due to reductions in both imaging artifacts and radiotherapy perturbations compared to titanium implants. We performed a review of the literature and highlight advantages and future areas of study for CFRP. Methods We performed a systematic review of the literature using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and identified 10 articles including 573 patients. Across all studies we reviewed patient demographics, tumor types treated, hardware-related features, complication rates, recurrence, survival, and follow-up. Results Across 10 studies, a total of 1371 screws placed. Surgical and non-surgical complications were reported in 18.3% of patients. Disease progression at the surgical site was detected in 7.3% of patients. There was no significant difference in clinical or hardware complications between CFRP or titanium implants. The most frequent complication attributable to implanted CFRP hardware included screw breakage in 2.4% and loosening in 1.7% of patients, respectively. Conclusion CFRP provide a unique tool in the setting of spinal oncology. With a safety profile comparable to titanium, we review the documented advantages of CFRP posterior implants compared to titanium, while also addressing their current limitations. Additionally, we highlight several areas of future research to identify the optimal patients who will achieve the greatest benefit of CFRP.

AbstractBackgroundThere is increasing need for noninvasive biomarkers of Alzheimer’s Disease (AD) neuropathologic change for early detection and intervention through risk‐factor modification and disease‐modifying therapies. One such biomarker is the prediction of chronological age from routine clinical tests such as an electrocardiogram (EKG) to discriminate between observed biological age from chronological age for healthy aging. Deviation of true age from predicted age has been associated with heart failure, hypertension, and coronary heart disease. However, the association between EKG‐based age and underlying neuropathology has not been studied.MethodWe used a cohort of 336 participants from the Mayo Clinic Study of Aging, a population‐based prospective study of residents in Olmsted County, Minnesota, with antemortem EKG and post‐mortem brain autopsy (Table 1 & 2). Age was predicted from EKG using a validated convolutional neural network algorithm. We used ordinal logistic regression to identify associations between lower neuropathologic scores of AD (Thal phase, neuritic plaque score, Braak stage, and overall AD neuropathologic change) and the Age‐Gap, defined as EKG‐predicted age minus chronological age. Results were controlled for true age, sex, and APOE e4 carrier status. Neuropathologic scales were grouped into none, low, intermediate, and high categories. Observations were weighted by the inverse of years between last EKG and time of death to account for the time difference between acquisition of EKG and autopsy.ResultWe found that an increasing Age‐Gap (i.e. older predicted age) was inversely associated with lower overall AD neuropathologic change (OR 0.93 [0.89, 0.97], p = 0.002). Investigation of the components of AD neuropathologic change showed that an increasing Age‐Gap was also inversely associated with lower amyloid metrics such as Thal phase (OR 0.85 [0.80, 0.89], p < 0.001) and neuritic plaque scores (OR 0.91 [0.87, 0.96], p < 0.001), but not tau metrics like Braak staging (OR 1.05 [1.00, 1.10], p = 0.05).ConclusionIn this work, we show that older predicted age on EKG, a noninvasive biomarker associated with vascular and biological aging, is associated with higher amyloid burden and neuropathologic change of AD.