Citations

Background: Tremor in multiple sclerosis (MS) is often refractory to medications. Deep brain stimulation (DBS) may help, but possible side effects and disease exacerbation limit its use. Objectives: Evaluate outcomes of DBS for MS-associated tremor. Methods: Retrospective review of 18 patients with MS-associated tremor who underwent DBS, analyzing Expanded Disability Status Scale (EDSS) and Fahn–Tolosa–Marin (FTM) tremor scores. Results: Median age at surgery was 49.5 years (range, 28–75), with postoperative follow-up 2.5 years (range, 0–22). No relapses (0/18) or new lesions (0/8) occurred postoperatively. All had ventral intermediate nucleus leads; other targets were not used in programming. EDSS remained stable (median 6 to 6.25; p = 0.2). FTM scores improved (median 14.5 to 10, p = 0.008). Patients with EDSS 3.5–6 had variable outcomes ( p = 0.02). Conclusions: DBS is a potential treatment for severe MS tremor and did not provoke relapse. Targeting VIM alone may optimize tremor control and maintain magnetic resonance imaging (MRI) access.

Abstract Disclosure: M. Salama: None. F. Pinto e Vairo: None. D. Hassan: None. S. Pittock: None. A. Lteif: None. O. Olson: None. A. Al Nofal: None. K. Leopold: None. S. Kumar: None. Objective: This study aimed to evaluate the effects of semaglutide on body mass index (BMI) and cardiometabolic profiles in adolescents with genetic variants associated with a likely high risk of monogenic obesity. Methods: A retrospective chart review was conducted for adolescents with severe obesity who underwent multigene panel testing for monogenic obesity and were treated with semaglutide. Results: Data from 27 adolescents were analyzed. At baseline, the median BMI percent of the 95th percentile (IQR) was 148 (135-189), with a mean age (SD) of 15.5 years (1.93) at treatment initiation and a median (IQR) treatment duration of 8 months (6-12). The median semaglutide dose (IQR) was 1.7 mg weekly (1.0- 2.4). Seven participants comprised the ‘’likely monogenic risk’’ group, characterized by predicted deleterious variants in dominant genes and/or carrying known dominant risk alleles. Twenty patients formed the “indetermined/negative “group, defined as harboring single rare variants in recessive genes or negative panel testing. In the likely monogenic risk group, weight loss was 8.5% with a median decrease in BMI % of the 95th %ile of 17 (95% CI 1.5- 22, p = 0.02). In the indetermined/negative group, weight loss was 7.6% with a median decrease in BMI % of the 95th %ile of 14 (95% CI 11.5- 27.5, p = <0.001). There was no statistically significant difference in median BMI % of the 95th % ile reduction between the two groups (p = 0.8) or BMI percent change (p = 0.89). Cardiometabolic changes in the likely monogenic risk group included reductions in HbA1c by 0.3% (95% CI: 0.15- 0.4, p = 0.03), total cholesterol by 15 mg/dL (95% CI: 7- 48, p = 0.03), and non-HDL cholesterol by 16.5 mg/dL (95% CI: 12- 40, p = 0.03). No significant changes were observed in fasting blood glucose, triglycerides, LDL cholesterol, HDL cholesterol, or ALT levels. The indetermined/negative group exhibited a significant reduction in HbA1c by 0.25% (95% CI 0.1 - 0.7| p = 0.009). Conclusion: Semaglutide treatment was associated with significant reductions in BMI and improvements in several cardiometabolic parameters in adolescents with likely high-risk monogenic obesity variants. These findings suggest semaglutide as a potentially effective therapeutic option for managing severe obesity in this population. Larger prospective studies are warranted to confirm and further assess these outcomes. Presentation: Monday, July 14, 2025

This cohort study examines the oncological, neurological, and serological profiles of adult male patients with testicular germ cell tumors and paraneoplastic neurologic syndromes.

Abstract Objectives γ‐Aminobutyric acid B receptor (GABA B R)‐IgG (immunoglobulin G) is an intermediate‐risk paraneoplastic autoantibody often associated with seizures. We aimed to assess the clinical and oncological features of GABA B R‐IgG autoimmune encephalitis (AE) and evaluate the performance of antibody testing. Methods Patients testing positive for GABA B R‐IgG in serum/cerebrospinal fluid (CSF) at Mayo Clinic Neuroimmunology Laboratory were identified. Archived sera were retested by cell‐based assay (CBA) at 1:100 and 1:200 dilutions. A live‐cell flow cytometry–based assay (LCFBA) was developed and validated using archived sera and CSF. True positivity included patients with classic presentations of GABA B R‐IgG AE or oncological explanations for antibody presence. Results Eighty‐six patients (median age 63 years; 43 female) presented with classic presentations of GABA B R‐IgG AE: encephalopathy with prominent seizures ( n = 55), status epilepticus ( n = 23), and rapidly progressive dementia ( n = 8). In addition, 44 patients (33%) had a false‐positive result for GABA B R‐IgG characterized by non‐specific symptoms/alternate diagnoses. Malignancy was identified in 78% of true‐positive patients, predominantly small cell lung carcinoma (SCLC). Testing serum at 1:100 dilution on CBA and using tissue immunofluorescence assay (IFA) in serum and CSF improved the identification of true‐positive patients ( p < 0.001). CBA at 1:100 dilution performed better than conventional CBA (at 1:10 dilution, p < 0.001) and tissue IFA ( p = 0.031). An in‐house LCFBA showed 100% sensitivity and specificity in CSF, performing similarly to conventional CBA ( p = 0.125) in CSF, but better than tissue IFA ( p = 0.031). Furthermore, serum LCFBA performed better than conventional CBA ( p = 0.022) and tissue IFA ( p = 0.006). LCFBA had the highest diagnostic accuracy and was closely followed by CBA at 1:100 dilution. Significance GABA B R‐IgG AE often presents as encephalopathy with seizures or status epilepticus in the context of an underlying SCLC. Multimodal evaluation using tissue IFA and fixed CBA at higher dilutions improves detection of true cases. LCFBA performs very well as a diagnostic test with very high sensitivity and specificity.

Background: Pharmacological options for severe obesity in early childhood are limited. While lisdexamfetamine is approved for attention-deficit/hyperactivity disorder (ADHD) and binge eating disorder, its role in managing obesity in children without these conditions has not been well studied. This case series assessed the effect of lisdexamfetamine on weight in young children with severe obesity but without ADHD or binge eating disorder. Methods: We conducted a retrospective chart review of six children with severe obesity treated with lisdexamfetamine for weight management. Demographic, anthropometric, and metabolic data were collected. One patient had Prader–Willi syndrome (PWS); the others had no known syndromic obesity. Results: Median age at treatment initiation was 6.5 years (range: 4.5–14), with equal male and female distribution. Median treatment duration was 12 months (range: 12–24), and mean maximum tolerated lisdexamfetamine dose was 35 mg (range: 10–60). In patients without syndromic obesity (n = 5) including one child with hypothalamic obesity, lisdexamfetamine significantly reduced body mass index (BMI) percent of the 95th percentile at 12 months (median change –24%, range: −18 to −28, p = 0.031), equating to a 13.8% reduction in BMI. Height percentile remained unchanged ( p = 0.59). The patient with PWS did not achieve lasting weight loss. Three children reported decreased appetite. Conclusions: Lisdexamfetamine was associated with weight loss in young children with severe obesity without genetic syndromes. Further studies are warranted to assess the long-term efficacy and safety of lisdexamfetamine in the management of pediatric obesity.

Abstract Purpose: Germ cell tumors (GCTs) pose significant diagnostic challenges due to the limited sensitivity and specificity of current tumor markers. Hereby we utilize phage immunoprecipitation sequencing (PhIP-Seq) technique to develop a unique immunosignature panel (iSIGN) with high sensitivity and specificity to improve the diagnosis and differentiation of GCTs. Patients and Methods: Serum samples from patients with confirmed gonadal or extragonadal GCTs and controls were collected from Mayo Clinic repositories. Controls included benign testicular lesions, autoimmune diseases, neurodegenerative disorders, and other cancers. Samples were randomized into development and validation cohorts. PhIP-Seq identified antigen-autoantibody interactions, and enrichment scores were calculated to develop a biomarker panel distinguishing GCT from non-GCT cases. A second biomarker panel was developed to predict seminoma from nonseminoma cases. Results: A total of 427 serum samples were analyzed, including 150 from GCT patients and 277 controls. For our primary model to distinguish GCT cases (GCT-iSIGN), 24 peptides from 16 antigens were identified based on significant differential autoantibody binding enrichment in GCT patients (p &lt; 0.05), ≥2 peptides per antigen, and enrichment scores ≥ 2.5-fold. GCT-iSIGN was highly sensitive (93%) and specific (99%) for identifying GCT cases from controls with an area under curve (AUC) of 0.93 and 9% Unknown Case Rate (UCR). The secondary panel (Sem-iSIGN) included 17 peptides corresponding to 5 unique proteins with high specificity (93%), moderate sensitivity (65%) and AUC of 0.77 to distinguish seminoma from nonseminoma GCT cases. Conclusion: This study demonstrates the potential use of PhIP-Seq to identify unique immunosignature panels that can serve as reliable biomarkers for GCT. These panels address the limitations of traditional markers and other proteomic techniques. This immunosignature model represents a cost-effective, stable, and scalable approach to enhancing GCT diagnosis and management. Citation Format: M Bakri Hammami, Andrew Knight, Haidara Kherbek, Brian Costello, Silvana De Lorenzo, Bradley C. Leibovich, John C. Cheville, Yong Guo, Jessica Sagen, Janet E. Olson, Alicia Algeciras-Schimnich, Sean J. Pittock, John R. Mills, Surendra Dasari, Divyanshu Dubey. iSIGN panel identifies germ cell tumors via whole-proteome phage immunoprecipitation sequencing [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Mechanisms of Cancer Immunity and Cancer-related Autoimmunity; 2025 Sep 24-27; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2025;13(9 Suppl):Abstract nr B027.

ABSTRACTClinicians often repeat aquaporin‐4‐immunoglobulin G (AQP4‐IgG) testing in case of possible seroconversion. Compared with older, less sensitive immunofluorescence assays (IFA), cell‐based assays (CBA) offer higher sensitivity. This study assessed the frequency of seroconversion in a retrospective Cleveland Clinic cohort (2006–2024) of 451 patients with an initial negative AQP4‐IgG result who underwent serial testing. Seroconversion occurred in 4.3% (7/170) of patients initially tested by tissue IFA, but in none (0/263) of those tested by CBA. The lack of AQP4‐IgG seroconversion after a negative CBA, with only rare cases after a negative IFA, suggests that repeat AQP4‐IgG testing is low yield unless prior testing used older methods such as IFA.