Multiple sclerosis (MS) is a progressive, degenerative disease that damages myelin sheaths in the central nervous system. The RADIANCE phase 2 study previously established that ozanimod, a sphingosine 1-phosphate receptor modulator, demonstrates greater efficacy on MRI measures in patients with relapsing MS. SUNBEAM, a randomized, double-dummy, double-blind, active-controlled phase 3 trial, was conducted at 152 centres across 20 countries to determine the efficacy and safety of ozanimod compared to intramuscular interferon beta-1a in those with relapsing MS. Relapsing MS was defined using the expanded disability status scale (EDSS) as well as either 1) one relapse in the past year or 2) one relapse in the past two years plus one or more gadolinium-enhancing lesions within 12 months of screening. Participants were randomly assigned to one of three groups: 1) daily oral ozanimod 1.0 mg, 2) daily oral ozanimod 0.5 mg, or 3) interferon beta-1a 30 ug. Researchers found that the annualized relapse rates were 0.35 (95% CI 0.28 to 0.44) for interferon beta-1a, 0.18 (95% CI 0.14 to 0.24) for ozanimod 1.0 mg (RR 0.52, 95% CI 0.41 to 0.66, p<0.0001), and 0.24 (95% CI 0.19 to 0.31) for ozanimod 0.5 mg (RR 0.69, 95% CI 0.55 to 0.86, p=0.0013). Over the course of the 12-month study, the number of participants who discontinued was 91, with 39.6% of these being from the interferon beta-1a group. The incidence of significant adverse events was low and similar across treatment groups, with no serious infections reported in ozanimod-treated participants. This study therefore shows that in patients with relapsing MS, ozanimod treatment results in a significantly decreased relapse rate with greater tolerance than interferon beta-1a. As such, ozanimod may represent an effective oral therapy for individuals with relapsing MS.