Pamrevlumab nonsuperior to placebo for boys with Duchenne muscular dystrophy

Key takeaways:

• Change in North Star Ambulatory Assessment at 52 weeks was not significant for treatment group or placebo.
• Nearly all study participants experienced a treatment-emergent adverse event.

For young ambulatory boys with Duchenne muscular dystrophy, treatment with pamrevlumab was nonsuperior to placebo after 52 weeks, according to a poster presentation at the 2024 MDA Clinical & Scientific Conference.

“In [Duchenne muscular dystrophy], fibrosis due to absent or dysfunctional dystrophin protein has been linked to overexpression of connective tissue growth factor (CTGF),” Brenda L. Wong, MD, a neurologist at the University of Massachusetts Medical School and Duchenne Muscular Dystrophy Center, and colleagues wrote. “Pamrevlumab is a fully human monoclonal antibody that binds to and inhibits the activity of CTGF.”

As there are no currently effective treatments for the condition outside of commonly prescribed corticosteroids, Wong and colleagues commenced a global phase 3, randomized, double-blind, placebo-controlled multicenter study to determine safety and efficacy of pamrevlumab for boys aged 6 to younger than 12 years with DMD who were able to walk.

A total of 73 participants were randomized 1:1 to receive either IV infusion of pamrevlumab 35 mg/kg every 2 weeks for 52 weeks or placebo, while also receiving systemic glucocorticoids (deflazacort or prednisone/prednisolone) during the study period.

The primary endpoint was change in North Star Ambulatory Assessment (NSAA) total score from baseline to week 52, with secondary endpoints including changes in four-stair climb velocity, 10-meter walk/run test, time to stand, and time to loss of ambulation at 52 weeks, along with tracking of treatment-emergent adverse events (TEAEs).

According to results, the difference in change of NSAA score was not significant (least squares mean: pamrevlumab, –3.022 [0.5505] vs. placebo, –2.494 [0.6962]).

Additionally, for all secondary endpoints, no significant differences were observed between those in the pamrevlumab group as well as those given placebo, while data further showed nearly all participants (pamrevlumab, n = 35; placebo, n = 35) experienced treatment-emergent adverse events, most of which were mild to moderate. No deaths occurred in either treatment group.

“Pamrevlumab was generally well-tolerated and no new safety concerns were identified for patients with [Duchenne muscular dystrophy],” Wong and colleagues wrote.