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Background Given the low haemorrhagic risk of intracranial low-grade dural arteriovenous fistulas (dAVFs), the benefits of routine intervention remain controversial. This study compares patient outcomes treated with stereotactic radiosurgery (SRS) versus conservative management. Method Multicentre retrospective analysis of the Consortium for Dural Arteriovenous Fistula Outcomes Research and the International Radiosurgery Research Foundation data. Inclusion criteria were (1) intracranial low-grade dAVF diagnosed by catheter-based angiography, (2) no prior dAVF-related haemorrhage and (3) management with upfront SRS (intervention group) or conservative management (observation group). The primary outcome was symptomatic improvement. Secondary outcomes included dAVF obliteration, up-conversion, haemorrhage, improvement and favourable modified Rankin Scale (mRS) at follow-up. Results 304 patients with a mean age of 56 years (SD 13.5) and a follow-up of 46.7 months (SD 45.5) were included. 135 (44.4%) were managed conservatively and 169 (55.6%) had upfront SRS. Compared with the observation group, symptomatic and mRS Score improvement (≥1-point decrease in baseline score) was more likely in the intervention group (95.1% vs 58.5%; OR=13.75 (5.61–33.69) and 37.0% vs 24.0%; OR=1.85 (1.09–3.15), respectively). These findings remained significant after multiple imputation and propensity score matching. Remaining outcomes were similar between groups. The all-cause mortality rate was 5.4% (n=16), unrelated to the dAVF or treatment. Five (3.0%) SRS-related complications were reported and resolved during the follow-up period. Conclusions SRS was associated with increased symptomatic and mRS Score improvement for low-grade dAVFs compared with conservative management. SRS had a low complication risk and did not appear to alter dAVF obliteration or haemorrhage. Future prospective trials on SRS as a first-line intervention for symptomatic low-grade dAVFs should be considered.

9009 Background: International Medical Graduates (IMGs) are a vital component of the US oncology workforce, representing nearly half of practicing medical oncologists. However, systemic barriers may influence their career trajectories differently. Understanding these challenges is essential for addressing workforce disparities and optimizing cancer care delivery across diverse geographic regions. Methods: We conducted a cross-sectional study of 13,497 medical oncologists using the 2024 Dec CMS Provider Dataset linked with the 2023 Rural-Urban Continuum Codes (RUCC). Medical oncologists were identified by their self-reported primary specialties, including Hematology/Oncology, Medical Oncology, and Hematopoietic Cell Transplant. Physicians were categorized by graduation origin (based on their self-reported medical school), career stage (early: 0–10 years, mid: 11–30 years, late: >30 years post-medical school graduation). The primary outcomes included practice at Main Campus of NCI Designated Cancer Centers (as an indicator of academic practice) and the geographical location of their practice (Metro, Non-Metro, Mixed). We employed chi-squared tests for statistical comparisons and performed stratified analyses by career stage to evaluate transition patterns over time. Results: 6920 IMGs constituted 48.7% of the oncology workforce, with similar gender distributions between IMG and non-IMG oncologists (37.9% vs 36.5% female, p=0.068). Notably, early career oncologists were less likely to be IMGs (IMG vs non-IMGs: 8.2% vs 12.5%, p<0.001). Compared to Non-IMGs, IMG oncologists are less likely to practice at main campuses of NCI Center (19.9% vs. 27.7%, p<0.001), especially as their career advances (all p<0.01). (Table). IMGs had higher representation in non-metropolitan areas than non-IMGs (11.4% vs 9.1%, p<0.001), particularly in late-career stages (14.7% vs 12.3%, p=0.033), indicating their unique role in serving underserved regions. (Table). Conclusions: Our findings reveal that, IMGs are less likely to practice at main campuses of NCI-Cancer Center than their non-IMG colleagues. Meanwhile, IMG oncologists are disproportionately serving rural communities. Supporting IMG pathways in oncology is critical to ensure a balanced cancer care delivery across the United States. Practice setting distribution and academic affiliation among international medical graduates (IMGs) and US graduates (USGs) by career stage. IMG (N=6,577) Non-IMG (N=6,920) IMG (N=6,577) Non-IMG (N=6,920) NCI Center Other NCI Center Other Metro Non-Metro/Mixed Metro Non-Metro/Mixed Total 19.9% 80.1% 27.7% 72.3% 88.6% 11.4% 90.9% 9.1% Career Stage Early (0-10y) 29.1% 70.9% 36.1% 63.9% 91.1% 8.9% 95.4% 4.6% Mid (11-30y) 21.3% 78.7% 28.8% 71.2% 90.1% 9.9% 91.6% 8.4% Senior (30+y) 15.0% 85.0% 22.0% 78.0% 85.3% 14.7% 87.7% 12.3%

Abstract Background Hypergammaglobulinemia poses a challenge for identifying and quantitating monoclonal proteins (M-protein). The Increased polyclonal immunoglobulin background can lead to imprecise estimation of the M-protein when quantitated by serum protein electrophoresis (SPEP). This is especially true using the perpendicular drop method of peak integration. Hypergammaglobulinemia also makes it difficult to detect small M-proteins on immunofixation electrophoresis. Overestimation of M-protein concentration can lead to unnecessary follow-ups while missing small M-proteins can mask the underlying diagnosis for patients. In this study, we retrospectively evaluated the prevalence and concentration of M-protein within polyclonal hypergamma backgrounds using immunocapture matrix-assisted laser desorption ionization time-of-flight mass-spectrometry (MASS-FIX). Methods We retrospectively analyzed 47061 unique patients tested for SPEP and MASS-FIX in 2022 at Mayo Clinic. If a patient underwent multiple tests during this period, only the first result was included in the analysis. Polyclonal hypergammaglobulinemia was defined as a gamma fraction &gt;1.7g/dL by SPEP. MASS-FIX was used to identify and isotype M-proteins. MASS-FIX was then combined with total immunoglobin quantitation (IgG, IgA or IgM) using nephelometry to quantify concentration of the M- protein using mathematical modeling (method currently under validation). Results Of the 47,061 unique patients, 24,796 were normal by SPEP (53%). M-spikes were present in 5,808 cases (12%). Hypogammaglobulinemia (gamma fraction &lt; 0.5g/dL) in 2897 cases (6%). Small non-quantifiable M-proteins by SPEP were present in 8363 cases (18%). [JC2] There were 4222 hypergamma cases in the cohort (9%), without a quantitative M-spike on SPEP. Of these, 16.1% (680/4222) patients had an M-protein by MASS-FIX. When polyclonal hypergamma was the sole SPEP abnormality, 5.5% were MASS-FIX positive. However, when a small abnormality pattern was observed within the polyclonal hypergamma background on SPEP, 50% of patients were MASS-FIX positive. The most common isotype was IgG (27.2%), followed by IgM (10.2%), IgA (8.1%), and biclonal (3.7%), which is similar to overall isotype distribution in other backgrounds. Using quantitative MASS-FIX, we identified that 95% MASS-FIX positive small monoclonal proteins in polyclonal hypergamma are &lt; 1 g/dL, which is the recommended limited of quantitation for M-protein using SPEP in setting of hypergammaglobulinemia. Conclusion Majority of polyclonal hypergammaglobulinemia cases (83.9%) do not have a monoclonal protein. MASS-FIX allows quantitation of small monoclonal proteins below the SPEP limit of quantitation, which can enhance our understanding of conditions which present with small M-proteins in a polyclonal hypergammaglobulinemia background. Small visual abnormalities within polyclonal hypergamma background on SPEP should be followed-up with immunofixation or MASS-FIX to confirm the presence or absence of M- proteins.

Abstract Background New immunoglobulin free light chain (FLC) assays are available. Despite analytical differences, it seems possible to use free light chain ratios (FLCr) generated by different assays and apply similar cut-points for the diagnosis of multiple myeloma. It is still unknown if we can use different assays for risk stratification of patients with monoclonal gammopathy of undetermined significance (MGUS). Methods Patients diagnosed with MGUS (N = 923) had FLC tested using a nephelometric FreeLite (Binding Site) assay on BNII instruments (Siemens) and a Sebia FLC assay (Sebia) on a DS2 ELISA analyzer (Dynex). Patients were followed up for progression to any plasma cell dyscrasia (PCD) for several decades. The Mayo MGUS risk stratification model for progression was assessed with both assays (M-spike &gt;1.5 g/dL; non-IgG isotype and abnormal FLCr), using package insert reference intervals (RI) and a new metric called principal component 2 (PC2). Results There were 94 events of progression to PCD in the cohort during a median of 38 years of follow-up. Freelite and Sebia FLC showed similar hazard ratios in the risk models for elevated FLCr. An alternative clinical decision point lower than the package insert RI was evaluated for the Sebia assay, which improved risk stratification for patients with a low FLCr. The PC2 metric showed similar performance to the FLCr in models, without superior benefit. Conclusions The Sebia ELISA-based FLC assay can be employed in an MGUS risk stratification model with similar performance to the original 2005 risk stratification model using the FreeLite assay.

Abstract Background Estimated glomerular filtration rate (eGFR) has become incorporated into multiple clinical management situations. Historically, equations included a Black race coefficient, which lacked biological plausibility and created potential to exacerbate health disparities. A new equation created in 2021 changed the weighting of age, sex, and creatinine by modeling against a diverse cohort and removing the Black race coefficient. Content A variety of clinical outcomes including kidney disease risk stratification, medication dosing, patient eligibility for clinical trials, and kidney donation are impacted by implementation of the new equation. Nearly 2 years after its initial publication, many studies have reported on observed analytical performance of the 2021 eGFR determined as diagnostic concordance and percentage of estimates within 30% of measured GFR. Additionally, the potential clinical impacts following adoption of the new eGFR among different patient populations has also been reported. Here we review these studies with a focus on assessing the data associated with the transition from 2009 to 2021 Chronic Kidney Disease Epidemiology Collaboration equations. Summary The reported interindividual variation in eGFR performance is significantly larger than any potential benefit derived from race coefficients. Both the 2021 eGFR and the 2009 eGFR analytical performance fall short of the validation cohort performance in most cohorts. However, the 2021 analytical is similar or better than the 2009 eGFR in most cohorts. Implementing the 2021 eGFR will remove a systematic overestimation of kidney function among Black patients.

Abstract Monoclonal gammopathy of undetermined significance (MGUS) is the most common plasma cell dyscrasia, present in ~3% of the population over 50yo. MGUS carries a 1% per year risk of malignant transformation for the rest of the affected individual’s life; long-term followup is recommended for all patients with MGUS. Different risk stratification models exist to evaluate potential for progression to malignancy. The Mayo risk model, published in 2005, uses the presence of 3 risk factors (abnormal free light chain (FLC) kappa/lambda ratio (KLr), M-spike ≥1.5 g/dL, non-IgG isotype) to confer a 3% per year risk of progression instead of the average 1%. For many years, the only FDA-approved measurement of FLC was the FreeLite assay (Binding Site), which uses polyclonal sheep antibodies. Recently, other FLC assays have become available in the US, including the Sebia FLC ELISA, which employs rabbit polyclonal antibodies. The assays have similar reference intervals (RI), however differences in analytical performance between the FreeLite and Sebia were previously reported. The objective of this study was to determine the performance of the Sebia FLC assay in the Mayo risk stratification model of MGUS patients for progression in comparison to FreeLite. Cryopreserved serum samples from a cohort of 923 MGUS patients with available long-term clinical followup (median follow-up time: 7.7years, range: 0.0 to 46.9) was used to measure FLC using Sebia ELISA on a DS2 automated platform (Dynex) and FreeLite on a Siemens BNII nephelometer. Passing-Bablok (P-B) regression and Spearman correlation were used to compare the KLr between assays. Cox proportional hazards models for progression to multiple myeloma or a related plasma cell malignancy were used to estimate the prognostic effect and ability to discriminate low and high risk of abnormal KLr for each assay. Analyses were carried out in R software. Correlation between Sebia and FreeLite KLr had a Spearman r = 0.796; P-B fit: Sebia KLr = 0.825*(FreeLite KLr) – 0.048, 95% CI of slope: 0.810-0.839). With FreeLite, 32.9% of patients had a KLr outside RI for the method. For Sebia, 48.0% of patients had a KLr outside the method specific RI. Despite the individual samples analytical disagreement, both assays showed similar clinical performance for risk stratification: Sebia abnormal KLr was associated with a hazard ratio (HR) of 2.77 (95%CI: 1.79-4.28 c-statistic=0.6505) for progression, while FreeLite abnormal KLr was associated with a HR of 3.31 (95%CI: 2.20-5.00, c-statistic=0.6529), and the difference in c-statistics was not statistically significant (p=0.93). The risk assessment is performed only once per patient, at the initial diagnosis of MGUS. The similarity in clinical performance between FreeLite and Sebia assays support the use of either method as a predictor for risk of progression for MGUS patients.

Abstract Background Interleukin 6 (IL-6) plays important roles in both innate and adaptive immunity, while dysregulated persistent production of IL-6 is involved in pathological development of various diseases associated with inflammation. Targeting the IL-6 pathway has led to many innovative treatment approaches. Siltuximab and Tocilizumab are monoclonal antibodies targeting IL-6 and IL-6 receptors respectively and have been FDA-approved for treatment of Castleman disease (Siltuximab), a rare lymphoproliferative disorder characterized by hyperproduction of IL-6 with an unknown prevalence, autoimmune diseases such as rheumatoid arthritis (Tocilizumab), and both shown potential as treatment for cytokine release syndrome in hospitalized COVID-19 patients. However, the presence of siltuximab can interfere with IL-6 assays, leading to the use of C-reactive protein (CRP) as a surrogate marker to monitor its efficacy. Aim To evaluate potential Siltuximab and Tocilizumab antibody interference on IL-6 measurements in three different IL-6 protein immunoassays. Method: Serum or EDTA plasma sample pools with different IL-6 concentrations ranging from low (2.3 – 11.1 pg/mL, around the reference interval cut-off for each assay) to high (18.5 – 1142 pg/mL), above reference interval cut-off for each assay) were utilized. Various concentrations of Siltuximab or Tocilizumab were spiked into the sample pools (at 10% of total volume) to achieve final concentrations up to 600 µg/mL and up to 300 µg/mL, respectively. Sample spiked with 10% saline were used as no-drug control. Three assays were used to measure IL-6 concentration: Beckman Access IL-6 assay on UniCel DxI 800 (Beckman Coulter), V-PLEX Plus human IL-6 assay on QuickPlex SQ120 (Meso Scale Diagnostics), and a Luminex cytokine panel assay developed in house (R&D systems) with upper reference interval limits of 6.4,1.8 and 5 pg/mL respectively. Results Siltuximab interfered with the measurement of IL-6 for all three assays. A significant interference (&gt; 20% reduction) was observed at even a very low siltuximab concentrations in all three assays (0.05 µg/mL). In the presence of 5 µg/mL or greater Siltuximab, a maximum reduction of 93%, 83%, and 40% was observed for Beckman Access, R&D Luminex assay, and V-PLEX Plus Mesoscale assay, respectively. Tocilizumab did not interfere with the measurement of IL-6 in the three assays when serum was spiked with up to 300 µg/mL of the drug. Conclusion Siltuximab falsely reduce the measured IL-6 concentration on all three immunoassays tested in this study to differing degrees, whereas Tocilizumab does not. Consider the therapeutic range of Siltuximab (84 to 332 µg/mL) for treatment of Castleman disease, and a half-life of 20.6 days, measurement of IL-6 may not be useful in Siltuximab treated patients for an extended time-period.

AbstractIntroductionA few copy number variations (CNVs) have been reported for Alzheimer's disease (AD). However, there is a lack of a systematic investigation of CNVs in AD based on whole genome sequencing (WGS) data.MethodsWe used four methods to identify consensus CNVs from the WGS data of 1,411 individuals and further investigated their functional roles in AD using the matched transcriptomic and clinicopathological data.ResultsWe identified 3,012 rare AD‐specific CNVs whose residing genes are enriched for cellular glucuronidation and neuron projection pathways. Genes whose mRNA expressions are significantly correlated with common CNVs are involved in major histocompatibility complex class II receptor activity. Integration of CNVs, gene expression, and clinical and pathological traits further pinpoints a key CNV that potentially regulates immune response in AD.DiscussionWe identify CNVs as potential genetic regulators of immune response in AD. The identified CNVs and their downstream gene networks reveal novel pathways and targets for AD.

Background: Hydrogen peroxide (H2O2)-induced oxidative stress has been demonstrated to induce afterdepolarizations and triggered activities in isolated myocytes, but the underlying mechanisms remain not fully understood. We aimed to explore whether protein kinase C (PKC) activation plays an important role in oxidative stress-induced afterdepolarizations. Methods: Action potentials and ion currents of isolated rabbit cardiomyocytes were recorded using the patch clamp technique. H2O2 (1 mM) was perfused to induce oxidative stress and the specific classical PKC inhibitor, Gö 6983 (1 μM), was applied to test the involvement of PKC. Results: H2O2 perfusion prolonged the action potential duration and induced afterdepolarizations. Pretreatment with Gö 6983 prevented the emergence of H2O2-induced afterdepolarizations. Additional application of Gö 6983 with H2O2 effectively suppressed H2O2-induced afterdepolarizations. H2O2 increased the late sodium current (INa,L) (n = 7, p < 0.01) and the L-type calcium current (ICa,L) (n = 5, p < 0.01), which were significantly reversed by Gö 6983 (p < 0.01). H2O2 also increased the transient outward potassium current (Ito) (n = 6, p < 0.05). However, Gö 6983 showed little effect on H2O2-induced enhancement of Ito. Conclusions: H2O2 induced afterdepolarizations via the activation of PKC and the enhancement of ICa,L and INa,L. These results provide evidence of a link between oxidative stress, PKC activation and afterdepolarizations.