<h3>Objective:</h3> To explore correlations between early MRI parameters and long-term clinical outcomes in patients with relapsing multiple sclerosis (RMS). <h3>Background:</h3> The ability of early MRI parameters to predict long-term clinical outcomes of RMS is not clear. <h3>Design/Methods:</h3> This post-hoc analysis pooled data from patients treated with ozanimod 0.92 mg/d in phase 3 SUNBEAM (NCT02294058) and RADIANCE (NCT02047734) who entered the DAYBREAK open-label extension (OLE) (NCT02576717), in which all patients received ozanimod 0.92 mg/d. Early MRI parameters included observed (baseline [BL]) and % change in (month 12 [M12]) whole brain volume (WBV), thalamic volume (TV), and cortical grey matter volume; BL and M12 gadolinium-enhancing (GdE) lesion count and T1 and T2 lesion volumes; and M12 new/enlarging T2 lesion count. Outcomes included number of relapses in the OLE, cognitive processing speed (Symbol Digit Modalities Test [SDMT]), and disability (Expanded Disability Status Scale [EDSS]) at OLE month 48 (M48). <h3>Results:</h3> Of the BL MRI outcomes, SDMT scores at OLE M48 correlated most strongly (ρ>0.46–<0.49) with T1 lesion volume (inverse correlation) and TV; EDSS at OLE M48 correlated less strongly with these MRI parameters (ρ>0.38–<0.42). For EDSS scores at OLE M48, the strongest correlations (ρ>0.41–<0.42) were observed with BL TV and WBV (inverse correlations). SDMT and EDSS correlated poorly with BL GdE lesion count (ρ<0.11). Of the M12 MRI outcomes, SDMT and EDSS scores correlated most strongly with T1 and T2 lesion volumes (SDMT, ρ>0.44–<0.50, inverse correlations; EDSS scores, ρ>0.34–<0.39). Relapses during the OLE were poorly correlated with BL and M12 MRI parameters (ρ<0.19). <h3>Conclusions:</h3> MRI lesion volumes and TV had stronger correlations with SDMT than with EDSS long term, suggesting MRI measures may be better predictors of cognition than physical disability over the long term. These results may be used to improve predictive models of clinical outcomes and treatment response in RMS. <b>Disclosure:</b> Dr. Arnold has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Biogen. Dr. Arnold has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Celgene. Dr. Arnold has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Frequency Therapeutics. Dr. Arnold has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Merck. Dr. Arnold has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Novartis. Dr. Arnold has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Roche. Dr. Arnold has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Sanofi. Dr. Arnold has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Shionogi. Dr. Arnold has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Xfacto communications. Dr. Arnold has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Eli Lilly. Dr. Arnold has received personal compensation in the range of $500-$4,999 for serving as a Consultant for EMD Serono. Dr. Arnold has stock in NeuroRx. Dr. Freeman has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Novartis. Dr. Freeman has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Bristol Myers Squibb. Dr. Freeman has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech, Inc. Dr. Freeman has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for EMD Serono. Dr. Freeman has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for TG therapeutics. Dr. Freeman has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Bristol Myers Squibb. Dr. Freeman has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Medscape, LLC. The institution of Dr. Freeman has received research support from Genentech. The institution of Dr. Freeman has received research support from NIH/NINDS. The institution of Dr. Freeman has received research support from NIH/NINDS. The institution of Dr. Freeman has received research support from PCORI. The institution of Dr. Freeman has received research support from EMD Serono. Dr. Freeman has received personal compensation in the range of $500-$4,999 for serving as a Participant in educational interview with Multiple Sclerosis Association of America. Dr. Hartung has received personal compensation in the range of $500-$4,999 for serving as a Consultant for BMS Celgene. Dr. Hartung has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Geneuro. Dr. Hartung has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Hartung has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Hartung has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Merck. Dr. Hartung has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Bayer. Dr. Hartung has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for TG Therapeutics. Dr. Hartung has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Roche. Dr. Hartung has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Frontiers Neurology. The institution of Dr. Montalban has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Biogen. The institution of Dr. Montalban has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Merck/ EMD Serono. The institution of Dr. Montalban has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Novartis. The institution of Dr. Montalban has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Teva. The institution of Dr. Montalban has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Hoffmann-La Roche. The institution of Dr. Montalban has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Actelion/ Janssen. The institution of Dr. Montalban has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for BMS/ Celgene. The institution of Dr. Montalban has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Sanofi/ Genzyme. Dr. Montalban has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Actelion/ Janssen. Dr. Montalban has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. Dr. Montalban has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for BMS/ Celgene. Dr. Montalban has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Merck/ EMD Serono. Dr. Montalban has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Montalban has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Hoffmann-La Roche. Dr. Montalban has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Sanofi-Genzyme. The institution of Dr. Montalban has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Immunic Therapeutics. The institution of Dr. Montalban has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Viatris/ Mylan. The institution of Dr. Montalban has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Sandoz. The institution of Dr. Montalban has received research support from Biogen. The institution of Dr. Montalban has received research support from Hoffmann-La Roche. The institution of Dr. Montalban has received research support from Sanofi/ Genzyme. The institution of Dr. Montalban has received research support from Merck/ EMD Serono. The institution of Dr. Montalban has received research support from Novartis. The institution of Dr. Montalban has received research support from Teva Pharmaceuticals. The institution of Dr. Montalban has received research support from Actelion/ Janssen. The institution of Dr. Montalban has received research support from BMS/ Celgene. Dr. Cohen has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Convelo. Dr. Cohen has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Mylan. Dr. Cohen has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biogen. Dr. Cohen has received personal compensation in the range of $500-$4,999 for serving as a Consultant for PSI. Dr. Cohen has received personal compensation in the range of $500-$4,999 for serving as a Consultant for EMD Serono. Dr. Cohen has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Gossamer Bio. Dr. Cohen has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Sage. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Roche Genentech. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Novartis. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Janssen/Actelion. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Atara Biotherapeutics. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biogen. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving as a Consultant for BMS. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Merk/EMD Serono. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Sanofi-Genzyme. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Atara Biotherapeutics. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Roche/Genentech. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Merck/EMD Serono. Dr. Bar-Or has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Sanofi/Genzyme. The institution of Dr. Bar-Or has received research support from Novartis. The institution of Dr. Bar-Or has received research support from Biogen. The institution of Dr. Bar-Or has received research support from Roche/Genentech. The institution of Dr. Bar-Or has received research support from Merck/EMD Serono. Dr. Steinman has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for TG Therapeutics. Dr. Steinman has received personal compensation in the range of $100,000-$499,999 for serving as a Consultant for 180 Life Sciences. Dr. Steinman has received personal compensation in the range of $100,000-$499,999 for serving as a Consultant for BioAtla. Dr. Steinman has received personal compensation in the range of $100,000-$499,999 for serving as a Consultant for Pasithea. Dr. Steinman has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for TG Therapeutics. Dr. Steinman has received personal compensation in the range of $0-$499 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for National Academy of Sciences. Dr. Steinman has received personal compensation in the range of $100,000-$499,999 for serving as an Expert Witness for Gibson Dunn. The institution of Dr. Steinman has received research support from Roche. The institution of Dr. Steinman has received research support from Novartis. Dr. Steinman has received intellectual property interests from a discovery or technology relating to health care. Dr. DeLuca has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Novartis. Dr. DeLuca has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biogen. Dr. DeLuca has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Celgene. Dr. DeLuca has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for Biogen. The institution of Dr. DeLuca has received research support from Biogen. Mr. Cheng has received personal compensation for serving as an employee of Bristol Myers Squibb. Dr. Riolo has received personal compensation for serving as an employee of Bristol Myers Squib. Diego Silva has received personal compensation for serving as an employee of BMS. Diego Silva has received stock or an ownership interest from BMS. Chahin Pachai has received personal compensation for serving as an employee of Bristol Myers Squibb. Chahin Pachai has stock in Bristol-Myers Squibb. The institution of Dr. Cree has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Atara. The institution of Dr. Cree has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Biogen. The institution of Dr. Cree has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for EMD Serono. The institution of Dr. Cree has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Novartis. The institution of Dr. Cree has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Sanofi. The institution of Dr. Cree has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for TG Therapeutics. The institution of Dr. Cree has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Autobahn. The institution of Dr. Cree has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Avotres. The institution of Dr. Cree has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Alexion. Dr. Cree has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Gossamer Bio. Dr. Cree has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Horizon. Dr. Cree has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Neuron23. Dr. Cree has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Boston Pharma. Dr. Cree has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Hexal/Sandoz. Dr. Cree has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Siemens. Dr. Cree has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Therini. Dr. Cree has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Immunic AG. The institution of Dr. Cree has received research support from Genentech. Dr. Cree has received publishing royalties from a publication relating to health care.