A Pilot Study of Dimethyl Fumarate in Pulmonary Arterial Hypertension Associated with Systemic Sclerosis

Given the poor treatment options for pulmonary arterial hypertension associated systemic sclerosis (SSc-PAH) patients, we sought to determine clinical safety and efficacy of Dimethylfumarate (DMF), an Nrf2 agonist, and the effects on biomarkers of oxidative stress on SSc-PAH in an exploratory interventional clinical trial.

The primary objectives were to assess the safety and efficacy of treatment with DMF in patients with SSc-PAH.

This was an investigator-initiated, double-blind, randomized, placebo-controlled trial conducted at two sites in the United States. The primary safety endpoint was the incidence of serious adverse events (SAEs) and all adverse events (AEs) in DMF compared to placebo-treated patients. The primary efficacy endpoint was the change in 6MWD from baseline to the end of treatment at Week 24 in DMF compared to placebo-treated patients.

Six participants were randomized to either placebo (n = 2) or DMF (n = 4). Baseline demographics were similar in both groups. A total of 25 adverse events (AEs) occurred in 6 subjects, with 14 AEs (56.0%) having occurred in DMF-treated subjects. 3 occurrences were identified as nausea AEs, and two participants withdrew due to nausea. One participant in the placebo group was withdrawn after a hospitalization SAE due to worsening of heart failure and shortness of breath secondary to anemia. One participant in each group completed protocol. Subjects in the DMF-treated group showed a non-significant reduced decline in 6MWD (relative mean change of -7.07%) from baseline to Week 24 as compared to placebo-treated subjects (relative mean change of -14.97%).

Patients treated for SSc-PAH with 2 and 3-drug regimens, as is now typical for these patients, tolerate DMF poorly. Our small samples size did not provide power to suggest efficacy. We suggest that Nrf2 is still a valid therapeutic target for future trials, using better tolerated Nrf2 agonists.