K.M. Al-Otaibi, B.S. Alghamdi, M.A. Al-Ghamdi et al. Multiple Sclerosis and Related Disorders (2022) 103556 number of specialized MS nurses and empowering them with the needed education and knowledge. The advisory group voted on and ranked the possible topics of interest for nurse MS education. Conclusion(s): MS Nurses have a vital and important role in the management of MS patient. In KSA there is a clear gap in the avail- ability of MS nurses in general with a clear shortage of certified MS nurses. It has become essential to prepare nurses in Saudi Arabia for MS patient management using preparatory courses and seminars to sup- port their important role in MS patient care and prepare them to get certified. doi: 10.1016/j.msard.2022.103622 Improvements in Quality of Life at 1 Year in Patients Treated with Cladribine Tablets for Highly Active Relapsing Multiple Sclerosis: An Interim Analysis of Clarify-MS Alessandra Solari a , Xavier Montalban b , Jeannette Lechner-Scott c,d , Fredrik Piehl e , Bruno Brochet f , Dawn Langdon g , Raymond Hupperts h , Krzysztof Selmaj i , Eva K. Havrdova j , Francesco Patti k , Luis Brieva l , Eva Maria Maida 13 , Nektaria Alexandri 14 , Paul Kamudoni 14 , Axel Nolting 14 , Birgit Keller 14 a Unit of Neuroepidemiology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy b Department of Neurology-Neuroimmunology Centre of Multiple Sclerosis of Catalonia (Cemcat), University Hospital Vall d’Hebron, Barcelona, Spain c University of Newcastle, Newcastle, NSW, Australia d Division of Neurology, John Hunter Hospital, Newcastle, NSW, Australia e Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Swe- den f INSERM U 1215, University of Bordeaux, Bordeaux, France g Department of Psychology, Royal Holloway, University of London, Egham, UK h Zuyderland Medisch Centrum Sittard, Maastricht University Medical Cen- ter, Maastricht, The Netherlands i Center for Neurology, Lodz, Poland j Charles University, First Medical Faculty, Prague, Czech Republic k Department of Medical and Surgical Sciences and Advanced Technologies, GF Ingrassia, University of Catania, and Azienda Ospedaliero Universitaria Policlinico “G Rodolico”- San Marco, University of Catania, Italy l IRBLLEIDA, Hospital Arnau de Vilanova, Lérida, Spain 13 Multiple Sclerosis Center, Vienna, Austria 14 Merck Healthcare KGaA, Darmstadt, Germany Background: Multiple sclerosis (MS) is a chronic disabling disease associated with negative effects on quality of life (QoL), including physi- cal and mental health. The objective of this investigation was to evaluate the change in QoL for patients with highly active relapsing MS at 1 year after initiating treatment with cladribine tablets (CladT), by assessing changes in the physical and mental health composite scores of Multiple Sclerosis Quality of Life-54 (MSQoL-54). Material(s) and Method(s): In CLARIFY-MS (NCT03369665), pa- tients with highly active relapsing MS were assigned to receive CladT 3.5 mg/kg cumulative dose over 2 years. Patients were recruited as per the EU label. Results in this interim analysis, conducted prior to the second year of treatment, were assessed using a mixed-effects linear model. Analyses were also conducted for cohorts separated by treat- ment naïve/prior disease-modifying therapy (DMT), and MSQoL report- ing performed before/after the start of the COVID-19 pandemic, as de- fined as the first reported fatality within each country. Result(s): Of the 482 patients treated with CladT, 70.1% were fe- male and the mean age was 37.4 years. Of the 426 patients who provided MSQoL-54 data, statistically significant (p<0.0001) improvements from Baseline to Month 12 were observed for physical and mental health composite scores with estimated changes of 4.51 (95% confidence in- terval [CI] 3.24–5.77) and 4.53 (95% CI 3.00–6.05), respectively. Sim- ilar trends were apparent for treatment naïve (n=121) and prior DMT (n=305) cohorts. There was no indication that the start of the COVID-19 pandemic had an impact on MSQoL-54 reporting. Regarding safety, 322 patients (66.8%) experienced at least one treatment-emergent adverse event, most commonly headache (16%), nasopharyngitis (9%), and lym- phopenia (9%). The majority of observed post-baseline lymphopenia events were grade 1–2; fewer patients reported grade 3 lymphopenia, no grade 4 lymphopenia was observed. Conclusion(s): With only half a therapeutic dose of CladT, this in- terim analysis demonstrates a statistically significant improvement in the physical and mental health composite scores of MSQoL-54 at 1 year. No new safety concerns were found in this 1-year interim analysis, with no new severe or opportunistic infections that could have an impact on the established benefit:risk profile of CladT in MS. doi: 10.1016/j.msard.2022.103623 Vitamin D3 Improves Behavioral Dysfunction and Promotes Re- myelination in Multiple Sclerosis Model Induced by Cuprizone Kholoud M. Al-Otaibi a,b , Badrah S Alghamdi c,d , Maryam A. Al-Ghamdi a , Ulfat Omar a a Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia b Department of Chemistry, Faculty of Science, Al-Baha University, Al-Baha, Saudi Arabia c Department of Physiology, Neuroscience Unit, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia d Pre-Clinical Research Unit, King Fahd Medical Research Center, King Ab- dulaziz University, Jeddah, Saudi Arabia Introduction: Multiple sclerosis (MS) is a chronic demyelination dis- ease of the central nervous system (CNS) that attacks the myelin sheath around the axon and damages it. Therefore, promoting remyelination is a critical strategy for treating MS to resolve and alleviate symptoms and protect myelin sheath from further damage. Vitamin D3 (Vit D3) supple- mentation is increasingly advised to patients with MS. Thus, this study aimed to investigate the effects of Vit D3 supplementation to improve remyelination in a cuprizone (CPZ) mouse model of MS. Material(s) and Method(s): The study was designed as two stages (de and re-myelination) for nine weeks; a total of 45 male SWR/J mice were divided into two groups, Control (n=15) and CPZ (n=30) groups for the first five weeks (demyelination stage). Mice in the control group were received a normal diet with ad libitum access through all exper- iment stages (de and re-myelination), whereas mice in the CPZ group were fed a diet mixed with 0.3% CPZ for 5 weeks to induce demyelina- tion. After week 5 CPZ diet was discontinued and followed by a normal diet for the last 4 weeks (remyelination stages), and mice in the CPZ group were re-divided into two groups: untreated and treated with Vit D3 orally once daily at 800 IU/kg. The effect of Vit D3 on behavioral changes was determined using grip strength meter and rotarod test. The degree of de and re-myelination in the corpus callosum (CC) of brains were assessed by Luxol Fast Blue (LFB) stain at weeks 5, 7, and 9. Result(s): The results showed that CPZ significantly reduced behav- ior performance in mice and myelin content in CC during the demyeli- nation stage. In contrast, mice’s grip strength and motor coordination performance revealed significantly improved behavior after treatment with Vit D3 at early and last remyelination stages (7 and 9 weeks, re- spectively). Furthermore, LFB staining showed that Vit D3 significantly promoted remyelination in the CC of the brain compared to the un- treated group at the remyelination stages. Conclusion(s): In conclusion, these results demonstrated that Vit D3 could improve remyelination in a CPZ-demyelinating mouse model of MS. doi: 10.1016/j.msard.2022.103624 23