Citations

Abstract Introduction Narcolepsy type 2 (NT2) is characterized by excessive daytime sleepiness, heterogeneous symptom severity, and typically normal endogenous orexin levels. The Vibrance-2 phase 2 study evaluated alixorexton, a selective orexin 2 receptor agonist, in patients with NT2. Methods Vibrance-2 was a placebo-controlled, dose-ranging phase 2 study. After a 2-week washout from current narcolepsy medications, adults with NT2 meeting ICSD-3-TR diagnostic criteria were randomized 1:1:1:1 to receive placebo or alixorexton once daily at doses of 10, 14, or 18mg for 8 weeks, followed by an optional 5-week open-label extension. Dual primary endpoints were the change from baseline to week 8 in mean sleep latency (MSL) on the Maintenance of Wakefulness Test (MWT) and on the Epworth Sleepiness Scale (ESS). Safety evaluation included treatment-emergent adverse events (TEAEs). P-values were adjusted for multiplicity. Results Ninety-three patients were randomized to placebo (n=24) or alixorexton (10mg, n=23; 14mg, n=22; 18mg, n=24); 90 completed double-blind treatment. At baseline, patients had severe symptoms (MWT: 5.6 minutes; ESS: 17.4). The study met its dual primary endpoints. At week 8, MSL on MWT increased 9.3, 6.7, and 6.7 minutes at 10, 14, and 18mg, respectively, from baseline versus placebo, with statistically significant differences observed for the 14 and 18mg doses (adjusted p< 0.05). ESS improved by -2.1, -3.2, and -3.6 points from baseline versus placebo at week 8 for the 10, 14, and 18mg groups, respectively, with statistical significance observed for the 18mg dose (adjusted p< 0.05), where more than 70% of patients achieved normalization. TEAEs in 10% of all alixorexton-treated patients through week 8 were pollakiuria, insomnia, micturition urgency, dizziness, and headache. Most TEAEs were mild-to-moderate with no serious TEAEs. Conclusion Vibrance-2 was the first large clinical trial in patients with NT2 to demonstrate positive results with an orexin 2 receptor agonist. Alixorexton resulted in statistically significant and clinically meaningful improvements in wakefulness and daytime sleepiness at Week 8 and was generally well tolerated. These results support phase 3 clinical development of alixorexton as a treatment for NT2. Support (if any) Alkermes, Inc.

Abstract Background Isolated REM sleep behavior disorder (iRBD) is a parasomnia that reflects an evolving α‐synucleinopathy disorder, providing an opportunity to study early pathological changes. While diffusion tensor imaging (DTI) studies have shown white matter changes in iRBD, Neurite Orientation Dispersion and Density Imaging (NODDI) may offer better biological specificity in characterizing microstructural alterations through measures of Neurite Density Index (NDI), Orientation Dispersion Index (ODI), and Free Water Fraction (FWF). Method We included 77 participants with polysomnography‐confirmed iRBD from the North American Prodromal Synucleinopathy (NAPS) Consortium and 154 age‐ and sex‐matched cognitively unimpaired controls from the Mayo Clinic Study of Aging. White matter microstructure was evaluated using standardized multi‐shell diffusion on 3T MRI, quantifying DTI metrics (fractional anisotropy, FA; and mean diffusivity, MD) and NODDI parameters across bilateral white matter tracts defined by the JHU “Eve” WM atlas. Group differences were assessed using conditional logistic regression, with correlations to motor performance evaluated using the Purdue Pegboard and Alternating Finger Tapping tests. Result Compared to controls, iRBD participants demonstrated widespread and bidirectional white matter changes across major white matter pathways (see Figure 1 for glass brain visualizations). While predominantly showing decreases, FA exhibited some increases, particularly in the corticospinal tract. MD showed a largely opposite pattern with predominantly increased values across tracts. NODDI metrics revealed complex bidirectional patterns: ODI was broadly increased across multiple tracts with focal decreases, while NDI showed a pattern of predominantly decreased values alongside localized increases. FWF demonstrated a mixed pattern with predominant decreases across most tracts. In addition, both DTI and NODDI metrics showed extensive, moderate correlations with the Purdue Pegboard Test and Alternating Finger Tapping performance ( T = 2.0, p < 0.05, Figure 2). Conclusion Our study highlighted widespread and complex bidirectional white matter microstructural alterations in individuals with iRBD, demonstrating significant correlations with dexterity and motor performance even during the prodromal stage. These results suggest that extensive white matter abnormalities occur early in prodromal α‐synucleinopathies and highlight the value of advanced diffusion imaging techniques in characterizing iRBD and its potential prediction of phenoconversion to overt neurodegenerative disorders.

Objective Lewy body disease (LBD) is a complex neurodegenerative disorder characterized by the accumulation of misfolded α‐synuclein in the brain. Neuroinflammation has long been implicated in LBD pathogenesis, and recent genetic studies in Parkinson's disease (a clinical manifestation of LBD) have shown consistent association with the human leukocyte antigen (HLA) gene complex. Here, we assessed whether variation in HLA alleles influences neuropathological burden in a neuropathologically‐defined series of LBD cases. Methods We conducted a comprehensive analysis of HLA allelic variants in a cohort of 539 LBD cases of European descent from the Mayo Clinic brain bank. High‐resolution whole‐genome sequencing was used, and the HLA alleles of each sample were called using the HLA*LA tool and assessed for association with neuropathological outcomes. Results Our analysis identified 1 significant ( P < 3.43 × 10 −5 ) and 4 suggestive ( P < 0.001) associations between certain HLA alleles and specific neuropathological outcomes in LBD, suggesting a potential role for HLA‐mediated immune mechanisms in disease progression and subtype differentiation. Specifically, HLA‐DPB1*06:01 was significantly associated with lower Lewy body counts in the parahippocampal gyrus ( P = 3.30 × 10 −5 ), with weaker and suggestive associations observed in the middle frontal ( P = 1.80 × 10 −4 ) and inferior parietal gyrus ( P = 6.33 × 10 −4 ). Additionally, although only suggestive, HLA‐DRB1*11:01 correlated with a lower Thal amyloid phase ( P = 1.56 x 10 −4 ), and HLA‐B*15:01 correlated with an increased risk of diffuse LBD ( P = 7.58 x 10 −4 ). Interpretation This study provides a detailed evaluation of the relationship between HLA alleles and LBD pathology, highlighting the importance of immune‐related genetic factors in the etiology of LBD. ANN NEUROL 2026;99:492–501

Abstract Anti-IgLON5 disease is an autoimmune encephalitis that presents with a heterogenous clinical phenotype, including sleep disorders, movement abnormalities and bulbar involvement. It is characterized by autoantibodies against IgLON5, 85% association with HLA-DQB1*05:∼ and a brainstem-dominant tauopathy. Cellular and murine models report pathogenic effects of the autoantibodies, and neurodegenerative factors suggest progressive atrophy as a common sequela. However, evidence from in vivo patient data and long-term follow-up is limited, and the degree of progression remains elusive. In this multicentre study, clinical and brain MRI data were collected from 127 patients across 12 countries to investigate the relationships between clinical presentations and the development of distinct brain atrophy patterns. Our data show that most patients develop a complex multisystem phenotype as the disease progresses; however, neuromuscular manifestations rarely emerge at later disease stages. By comparison to healthy controls, this disease presents with severe substructure-specific atrophy, especially affecting the hypothalamus, brainstem, accumbens and basal ganglia, which, in age-independent analyses, show significant ventricular enlargement and also suggest progression of brainstem atrophy over the disease course. Moreover, the focality of atrophy was functionally linked to specific symptoms, with more severe involvement of the basal ganglia in patients with movement disorders, and greater atrophy in the hippocampus and thalamus in patients with cognitive impairment. Taken together, our results provide evidence of distinct atrophy patterns in anti-IgLON5 disease, which closely mirror sites of pathophysiologic processes, including autoantibody binding and tau deposition. Our data emphasize the brainstem as the pathophysiological hub of the disease and provide normative data for the incorporation of atrophy measurements into routine clinical assessments and future treatment studies to monitor disease trajectory and evaluate future treatment strategies.

Abstract Introduction Jazz DUET (Develop hypersomnia Understanding by Evaluating low-sodium oxybate Treatment) is a phase 4, prospective, multicenter, single-arm, multiple-cohort, open-label study (NCT05875974) evaluating the effectiveness of low-sodium oxybate (LXB, Xywav®) treatment on outcomes including sleep quality (using polysomnography [PSG] and self-reported questionnaires) in participants with narcolepsy or idiopathic hypersomnia. Data reported here are from the narcolepsy cohort. Methods DUET included a screening period (with 2-week washout for current oxybate users), an 8-day baseline (BL) period, a 2- to 8-week LXB titration period, a 2-week stable-dose period (SDP), an 8-day end-of-treatment (EOT) period, and a 2-week safety follow-up. Participants underwent nocturnal PSG (ad libitum protocol) at BL and EOT. The Karolinska Sleepiness Scale (KSS) was administered 90 minutes post-awakening from PSG to measure situational sleepiness (9-point scale; 1=“extremely alert” to 9=“extremely sleepy, can’t keep awake”). Participants completed an electronic sleep diary (eDiary) daily during the BL and EOT periods, including questions regarding nightly sleep patterns, total sleep time (TST), sleep quality (5-point scale; “very good” to “very poor”), and how rested/refreshed the participant felt upon awakening (5-point scale; “very well” to “not at all”). Completion of ≥5 eDiary days during the 8-day assessment before PSG visits was required for analysis. eDiary and KSS data were analyzed in the completer set (enrolled participants who were dosed with LXB and completed SDP and PSG at EOT). Results Fifty-five participants with narcolepsy (type 1, n=26; type 2, n=29) enrolled (completer set, n=34). Most were female (40/55; 73%) and White (44/55; 80%); mean (SD) age was 33.4 (12.9) years. Mean (SD) self-reported nocturnal TST at BL (n=32) and EOT (n=20) was 8.1 (1.6) and 8.3 (0.9) hours, respectively. The percent of participants rating their sleep quality as “very good”/“good” increased from 15.6% (BL) to 70.0% (EOT). The percent of participants with rested sleep (“very well”/“well”/“somewhat” rested) increased from 46.9% (BL) to 90.0% (EOT). Likewise, mean (SD) rating of self-reported sleepiness decreased from 5.1 (2.0) at BL to 3.8 (1.9) at EOT. Conclusion Following open-label LXB treatment, participants with narcolepsy reported improvements in sleep quality and feeling more rested and less sleepy upon awakening. Support (if any) Jazz Pharmaceuticals

Abstract Introduction Jazz DUET (Develop hypersomnia Understanding by Evaluating low-sodium oxybate Treatment) is a phase 4, prospective, multicenter, single-arm, multiple-cohort, open-label study (NCT05875974) evaluating effectiveness of low-sodium oxybate (LXB, Xywav®) treatment on outcomes including polysomnography (PSG)-based sleep architecture in participants with idiopathic hypersomnia or narcolepsy (type 1 [NT1] or 2 [NT2]). Methods DUET included a screening period (2-week washout for current oxybate users), 8-day baseline (BL) period, 2- to 8-week LXB titration period, 2-week stable-dose period (SDP), 8-day end-of-treatment period (EOT), and 2-week safety follow-up. Participants underwent nocturnal PSG (ad libitum protocol) at BL and EOT. PSGs were scheduled to allow a minimum of 10 hours in bed, unless the participant naturally awakened earlier; bedtime was determined by habitual bedtime. PSG recordings were centrally scored. Data were analyzed for participants in the narcolepsy cohort completer set. Total shifts from deeper to lighter sleep stages was defined as N1/N2/N3/REM to wake and N2/N3/REM to N1. Key secondary endpoints (total stage shifts, N3 duration) were controlled for multiplicity with sequential testing; other P-values are considered nominal. Results Fifty-five participants with narcolepsy enrolled (NT1, n=26; NT2, n=29); 34 completed the study (NT1, n=16; NT2, n=18). Most were female (73%) and White (80%) (mean±SD age, 33.4±12.9 years). Mean±SD total sleep time (TST) at BL/EOT was 453.2±80.1/452.4±70.0 minutes (LSM change [95% CI]: –0.78 [–23.7, 22.1]; P=.9451). Mean±SD number of total shifts from deeper to lighter sleep stages at BL/EOT was 54.6±28.0/41.6±25.6 (LSM [95% CI]: –13.1 [–19.0, –7.1]; P&lt;.0001 [controlled for multiplicity]). Mean±SD time spent in N1 at BL/EOT was 45.3±28.4/37.2±25.2 minutes (LSM [95% CI]: –8.1 [–14.9, –1.4]; P=.0196), % of stage was 10.4%/8.2% (P=.0037); in N2 was 241.8±61.2/243.3±76.1 minutes (LSM [95% CI]: 1.5 [–23.6, 26.6]; P=.9040), 53.1%/53.2% (P=.9869); in N3 was 61.1±34.8/106.1±69.5 minutes (LSM [95% CI]: 45.0 [27.0, 63.0]; P&lt;.0001 [controlled for multiplicity]), 13.7%/24.0% (P&lt;.0001); and in REM was 105.0±42.7/65.8±33.1 minutes (LSM [95% CI]: –39.2 [–50.8, –27.5]; P&lt;.0001), 22.8%/14.7% (P&lt;.0001). Conclusion Participants with narcolepsy taking open-label LXB showed negligible change in TST and N2, increased N3, decreased N1 and REM, and fewer shifts from deeper to lighter stages of sleep. Support (if any) Jazz Pharmaceuticals

Abstract Encephalitis with antibodies to leucine-rich glioma-inactivated 1 (LGI1-Ab-E) is a common form of autoimmune encephalitis, presenting with seizures and neuropsychiatric changes, predominantly in older males. More than 90% of patients carry the human leukocyte antigen (HLA) class II allele, HLA-DRB1*07:01. However, this is also present in 25% of healthy controls. Therefore, we hypothesized the presence of additional genetic predispositions. In this genome-wide association study and meta-analysis, we studied a discovery cohort of 131 French LGI1-Ab-E and a validation cohort of 126 American, British and Irish LGI1-Ab-E patients, ancestry-matched to 2613 and 2538 European controls, respectively. Outside the known major HLA signal, we found two single nucleotide polymorphisms at genome-wide significance (P &lt; 5 × 10−8), implicating PTPRD, a protein tyrosine phosphatase, and LINC00670, a non-protein coding RNA gene. Meta-analysis defined four additional non-HLA loci, including the protein coding COBL gene. Polygenic risk scores with and without HLA variants proposed a contribution of non-HLA loci. In silico network analyses suggested LGI1 and PTPRD-mediated interactions via the established receptors of LGI1, ADAM22 and ADAM23. Our results identify new genetic loci in LGI1-Ab-E. These findings present opportunities for mechanistic studies and offer potential markers of susceptibility, prognostics and therapeutic responses.

Abstract Anti-IgLON5 disease is a rare and likely underdiagnosed subtype of autoimmune encephalitis. The disease displays a heterogeneous phenotype that includes sleep, movement and bulbar-associated dysfunction. The presence of IgLON5-antibodies in CSF/serum, together with a strong association with HLA-DRB1*10:01∼DQB1*05:01, supports an autoimmune basis. In this study, a multicentric human leukocyte antigen (HLA) study of 87 anti-IgLON5 patients revealed a stronger association with HLA-DQ than HLA-DR. Specifically, we identified a predisposing rank-wise association with HLA-DQA1*01:05∼DQB1*05:01, HLA-DQA1*01:01∼DQB1*05:01 and HLA-DQA1*01:04∼DQB1*05:03 in 85% of patients. HLA sequences and binding cores for these three DQ heterodimers were similar, unlike those of linked DRB1 alleles, supporting a causal link to HLA-DQ. This association was further reflected in an increasingly later age of onset across each genotype group, with a delay of up to 11 years, while HLA-DQ-dosage dependent effects were also suggested by reduced risk in the presence of non-predisposing DQ1 alleles. The functional relevance of the observed HLA-DQ molecules was studied with competition binding assays. These proof-of-concept experiments revealed preferential binding of IgLON5 in a post-translationally modified, but not native, state to all three risk-associated HLA-DQ receptors. Further, a deamidated peptide from the Ig2-domain of IgLON5 activated T cells in two patients, compared with one control carrying HLA-DQA1*01:05∼DQB1*05:01. Taken together, these data support a HLA-DQ-mediated T-cell response to IgLON5 as a potentially key step in the initiation of autoimmunity in this disease.

Abstract Study Objectives Rapid eye movement sleep behavior disorder (RBD) is strongly associated with phenoconversion to an overt synucleinopathy, e.g. Parkinson’s disease (PD), Lewy body dementia, and related disorders. Comorbid traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD)—henceforth “neurotrauma” (NT)—increase the odds of RBD by ~2.5-fold and are associated with an increased rate of service-connected PD in Veterans. Thus, RBD and NT are both independently associated with PD; however, it is unclear how NT influences neurological function in patients with RBD. Methods Participants ≥18 years with overnight polysomnogram-confirmed RBD were enrolled between 8/2018 to 4/2021 through the North American Prodromal Synucleinopathy Consortium. Standardized assessments for RBD, TBI, and PTSD history, as well as cognitive, motor, sensory, and autonomic function, were completed. This cross-sectional analysis compared cases (n = 24; RBD + NT) to controls (n = 96; RBD), matched for age (~60 years), sex (15% female), and years of education (~15 years). Results RBD + NT reported earlier RBD symptom onset (37.5 ± 11.9 vs. 52.2 ± 15.1 years of age) and a more severe RBD phenotype. Similarly, RBD + NT reported more severe anxiety and depression, greater frequency of hypertension, and significantly worse cognitive, motor, and autonomic function compared to RBD. No differences in olfaction or color vision were observed. Conclusions This cross-sectional, matched case:control study shows individuals with RBD + NT have significantly worse neurological measures related to common features of an overt synucleinopathy. Confirmatory longitudinal studies are ongoing; however, these results suggest RBD + NT may be associated with more advanced neurological symptoms related to an evolving neurodegenerative process.