WCN19-2026 Journal of the Neurological Sciences 405S (2019) 104771 Poster Session 2 Efficacy of satralizumab as monotherapy in pre-specified sub- groups of SAkuraStar, a double-blind placebo-controlled phase 3 clinical study in patients with neuromyelitis optica spectrum disorder (NMOSD) Jeffrey L. Bennett a , B. Greenberg b , A. Traboulsee c , L. Szczechowski d , E. Fox e , S. Shkrobot f , T. Yamamura g , Y. Terada h , Y. Kawata h , H.C. von Büdingen i , G. Klingelschmitt i , A. Gianella-Borradori j , B.G. Weinshenker k a University of Colorado School of Medicine, Aurora, CO, USA b University of Texas Southwestern Medical Center, Dallas, TX, USA c University of British Columbia, Vancouver, Canada d Silesian Centre of Neurology, Katowice, Poland e Central Texas Neurology Consultants, Round Rock, TX, USA f Ternopil State Medical University, Ternopil, Ukraine g National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan h Chugai Pharmaceutical Co., Ltd, Tokyo, Japan i F. Hoffmann-La Roche Ltd, Basel, Switzerland j Chugai Pharma USA LLC, Berkeley Heights, NJ, USA k Mayo Clinic, Rochester, MN, USA Background Interleukin-6 (IL-6) is implicated in the immune pathology of neuromyelitis optica spectrum disorder (NMOSD). Satralizumab, a humanized recycling monoclonal antibody that binds to the IL-6 receptor, reduced risk of relapse in patients with NMO or NMOSD as add-on therapy in the SAkuraSky study (NCT02028884) and as monotherapy in the SAkuraStar study (NCT02073279). Objective Evaluate the efficacy of satralizumab monotherapy vs placebo for relapse prevention in pre-defined subgroups of the SAkuraStar study. Methods SAkuraStar is a randomized, double-blind, Phase 3 study comparing satralizumab monotherapy with placebo. 95 patients with NMO or NMOSD, with ≥1 documented relapse in the year prior to screening, were randomized 2:1 to satralizumab (120 mg s.c.) or placebo. The primary endpoint was time to first protocol-defined relapse (PDR). Pre- specified subgroup analyses assessed treatment response by AQP4-IgG serostatus, prior therapy, and relapse history. Results Overall, satralizumab reduced risk of PDR by 55% vs placebo (hazard ratio [HR] 0.45; 95% confidence interval [CI] 0.23–0.89; p = .018). There was a 74% reduction in PDR risk with satralizumab vs placebo in AQP4-IgG-seropositive patients (HR 0.26; 95% CI 0.11– 0.63). In AQP4-IgG-seronegative patients, the HR was 1.19 (95% CI 0.30–4.78). HRs for additional subgroups are provided in Table 1. The proportion of relapse-free patients at Weeks 48 and 96 in the AQP4- IgG-seropositive and seronegative subgroups will be presented. Conclusions Satralizumab was effective in reducing risk of PDR in patients with NMO or NMOSD, particularly in AQP4-IgG-seropositive patients. The study was not powered for subgroup analyses; therefore, results should be interpreted with caution. doi:10.1016/j.jns.2019.10.1109 WCN19-2058 Journal of the Neurological Sciences 405S (2019) 104772 Poster Session 2 A study of clinical,radiological and thrombophilia profile in cerebral venous sinus thrombosis D. Dave, F. Khan, S. Rohatgi, S. Nirhale, P. Rao, P. Naphade Neurology, Dr. D.Y. Patil Medical College, Pune, India Introduction A prospective, observational study was done at a tertiary care hospital in Pune to describe the clinical, radiological and thrombophilia profile of cerebral venous sinus thrombosis in an Indian population. Methods 30 patients with clinical and MRI features suggestive of cerebral venous sinus thrombosis (CVST), were studied with detailed clinical evaluation and pro-thrombotic work up. All were followed up monthly for 6 months, to assess the response to therapy and clinical outcomes. Abstracts / Journal of the Neurological Sciences 405S (2019) 116542 172