Long-term safety and efficacy of teriflunomide in patients with relapsing multiple sclerosis: Results from the TOWER extension study

Background: In the phase 3 TOWER core study (NCT00751881), the efficacy and safety of teriflunomide compared with placebo were demonstrated in patients with relapsing forms of multiple sclerosis (RMS). Here, the long-term safety and efficacy outcomes from the TOWER extension study (NCT00751881) are reported. Methods: All patients who entered the extension (N = 751) were assigned to teriflunomide 14 mg and assessed for long-term safety and efficacy. Results: Of 751 patients in the TOWER extension study, 253, 265, and 233 patients received placebo/teriflunomide 14 mg, teriflunomide 7 mg/14 mg, and teriflunomide 14 mg/14 mg, respectively. Median teriflunomide exposure was 4.25 years (maximum 6.3 years). The overall frequency of adverse events (AEs) was comparable across treatment groups, but a higher proportion of patients in the teriflunomide 7 mg/14 mg (12.4%) and 14 mg/14 mg (12.4%) groups had serious AEs compared with the placebo/teriflunomide 14 mg group (6.4%). Alanine aminotransferase increase and hair thinning occurred at a higher frequency in the placebo/teriflunomide 14 mg group (11.2% and 14.3%, respectively) compared with the teriflunomide 7 mg/14 mg (3.0% and 4.5%, respectively) and 14 mg/14 mg groups (5.2% and 4.3%, respectively). The incidences of AEs of interest (hematologic and hepatic effects, peripheral neuropathy, hypertension, and malignancy) were low and comparable across treatment arms. Disability worsening and adjusted annualized relapse rates were low and stable over time, and mean Expanded Disability Status Scale scores were unchanged over time, for all treatment groups. Conclusion: In the TOWER extension study, the efficacy of teriflunomide 14 mg was maintained in patients with RMS. No new or unexpected AEs were observed with teriflunomide treatment, supporting a safety profile in the extension that was consistent with the core trial. These findings support the positive benefit:risk profile of teriflunomide as a long-term immunomodulatory therapy.