Real-World Analysis Affirms the High Persistence and Adherence Observed with Diroximel Fumarate in Patients with Multiple Sclerosis.

INTRODUCTION: Adherence to disease-modifying therapies is key for achieving optimal outcomes in multiple sclerosis (MS). Diroximel fumarate (DRF) is an oral fumarate approved for treatment of relapsing forms of MS. It has the same pharmacologically active metabolite as dimethyl fumarate (DMF) and similar efficacy and safety profiles, but with demonstrated fewer gastrointestinal (GI) related adverse events (AEs). There are limited data characterizing persistence and adherence to DRF in the real world. METHODS: This retrospective analysis of the AcariaHealth Specialty Pharmacy Program included patients with MS initiating DRF from 1 December 2019 to 30 January 2021. This analysis evaluated persistence, measured as proportion of patients remaining on therapy; discontinuation rate due to GI AEs; and adherence measured by proportion of days covered (PDC). RESULTS: Overall, 1143 patients were included; 433 (37.9%) patients had been treated with prior DMF and switched to DRF. Persistence was high in both groups: the estimated proportion of patients remaining on DRF at 16 months was 82.3% [95% confidence internal (CI) 77.2-86.3%], and 90.1% (95% CI 82.2-94.6%) in the DMF to DRF group. Fifty-two (4.5%) patients overall and 15 (3.5%) in the DMF switch subgroup discontinued DRF due to GI AEs. Mean PDC was 90.8% (95% CI 89.2-92.5%), and 85.4% (95% CI 83.3-87.4%) of patients achieved PDC ≥ 80% in the overall population. In the DMF to DRF group, mean PDC was 90.7% (95% CI 88.0-93.5%), and 84.8% (95% CI 81.4-88.1%) of patients achieved PDC ≥ 80%. CONCLUSION: In this analysis of  > 1000 patients treated with DRF in real-world clinical practice, overall persistence at 16 months was high, treatment discontinuation due to GI AEs was low, and patients were highly adherent to therapy. Of 433 patients who switched from DMF to DRF, most (> 90%) were able to tolerate and persist on DRF after switching. Graphical abstract available for this article.