Five Years of Ublituximab in Multiple Sclerosis

Importance In the 2-year Study to Assess the Efficacy and Safety of Ublituximab in Participants With Relapsing Forms of Multiple Sclerosis (ULTIMATE) I and II randomized clinical studies, disease activity was significantly reduced with ublituximab vs teriflunomide in participants with relapsing multiple sclerosis (RMS). Objective To evaluate long-term ublituximab clinical efficacy and safety. Design, Setting, and Participants The 2-year, multicenter, randomized, active-controlled, double-blind period (DBP) of the ULTIMATE I and II phase 3 studies occurred September 2017 to November 2020. Enrollment in the ongoing ULTIMATE open-label extension (OLE) study began November 2019; data cutoff for this analysis was January 1, 2024. Intervention ULTIMATE OLE participants continued ublituximab (UBL-UBL) or switched from teriflunomide to ublituximab (TER-UBL). Main Outcomes and Measures Efficacy (annualized relapse rate [ARR], 24-week confirmed disability progression [CDP24], and 24-week confirmed disability improvement [CDI24]) and safety were key outcomes. Results Of 985 adults with RMS who completed ULTIMATE I and II, 851 enrolled in the ULTIMATE OLE and were included in the analysis. On DBP completion, more than 85% of participants (UBL-UBL, 422 of 494; TER-UBL, 429 of 491) entered the OLE, of whom more than 70% (UBL-UBL, 297 of 422; TER-UBL, 327 of 429) continued taking ublituximab at year 5 (OLE year 3) at data cutoff, making up the analysis population (mean [SD] age, 38.5 [9.7] years; 532 female [62.5%]). TER-UBL participants experienced a 58.4% ARR reduction at 1 year after the switch (0.182 vs 0.076; rate ratio, 0.42; 95% CI, 0.29-0.60; P < .001), and ARR continued to decrease to 0.048 (year 4) and 0.045 (year 5). UBL-UBL participants had further ARR reductions after the DBP (0.053, 0.032, and 0.020 for years 3, 4, and 5, respectively). At year 5, CDP24 was 8.0% in UBL-UBL participants vs 14.3% in TER-UBL participants ( P = .01), and CDI24 was 17.0% in UBL-UBL participants vs 12.2% in TER-UBL participants ( P = .02). Adverse events were consistent with the established safety profile from pivotal trials, with exposure-adjusted incidence rates per 100 participant-years of serious infections (excluding COVID events) of 2.10 (UBL-UBL) and 2.58 (TER-UBL). On average, immunoglobulin levels remained above the lower limit of normal, and no significant differences in serious infection rates were observed regardless of immunoglobulin level. Conclusions and Relevance Results reveal that sustained clinical benefits were observed with 5 years of ublituximab treatment: ARR in year 5 showed 1 relapse per 50 participant-years of ublituximab treatment and 92% of UBL-UBL participants remained free from CDP24. Results confirm long-term ublituximab benefits and early initiation of high-efficacy treatment. Trial Registration ClinicalTrials.gov Identifier: NCT04130997