Background

Diroximel fumarate (DRF) is an oral fumarate recently approved in the United States for relapsing forms of multiple sclerosis (MS). DRF demonstrated favorable gastrointestinal (GI) tolerability in clinical studies of MS patients (pts). Discontinuations due to GI adverse events (AEs) were low (0.7%) in an open-label 2-year study. In a randomized study versus dimethyl fumarate (DMF), fewer pts reported GI AEs (35%, 88/253 DRF vs 49%,123/251 DMF) and GI AEs leading to discontinuation (0.8% DRF vs. 4.8% DMF); GI AEs were less frequently reported as moderate/severe for DRF (23%, 20/88) vs DMF (40%, 49/123). It is important to characterize DRF persistence in a real-world setting and effectiveness across different patient types and geographies.

Objectives

To describe the novel design of the DRF EXPERIENCE (EXPloring diroximEl fumarate Real-world experIENCE) Study Initiative.

Methods

A Phase IV DRF study should collect data on meaningful real-world outcomes, including treatment persistence, real-world tolerability, and clinical effectiveness, including cognitive changes, to align with evolving treatment goals. As DRF was designed to reduce treatment burden, impact on quality of life should also be assessed. Country-specific nuances due to unique healthcare environments, ethnicity, and cultural considerations diminish the utility of a single-study design.

Results

The DRF EXPERIENCE Study Initiative uses a novel design comprising 4 individual studies, each conducted in different regions but anchored by a core protocol to characterize the early experience in pts initiating DRF per routine care. The core protocol defines a set of required assessments for each study, but also allows flexibility to include others that address country-specific research questions. The primary objective is to characterize persistence to DRF at 1 year. Core protocol assessments include relapse, disability, cognitive changes, and pt-reported Neuro-QoL. Each study will enroll ~200 pts; the pooled total sample size of ~800 will improve ability for subgroup analyses. Pts will be followed for 2 years and include those newly initiating a disease modifying therapy (DMT) or switching from previous DMTs (including prior DMF).

Conclusions

The DRF EXPERIENCE Study Initiative uses a novel design to characterize the improved GI tolerability profile and effectiveness of DRF in MS pts in the real-world and will be informative to providers and patients when considering MS treatment goals together with the burden of therapy.

Supported by: Biogen