Regenxbio Inc. (Nasdaq: RGNX) has announced significant progress in its Phase I/II/III CAMPSIITE® trial of RGX-121 for the treatment of Mucopolysaccharidosis Type II (MPS II), commonly known as Hunter syndrome. The company revealed that the pivotal phase of the trial has successfully met its primary endpoint with statistical significance.
The topline results, presented at the 20th Annual WORLDSymposium™ by trial investigator Paul Harmatz, M.D. from UCSF Benioff Children’s Hospital, are highly promising. Kenneth T. Mills, President and CEO of REGENXBIO, expressed enthusiasm, stating, “The data from this pivotal trial supports that RGX-121 changes the course of the disease by restoring the missing gene in boys with Hunter syndrome and has the potential to significantly improve vital brain function for patients.”
The pivotal trial demonstrated that patients treated with RGX-121 achieved a remarkable reduction in cerebrospinal fluid (CSF) levels of D2S6, a key biomarker of brain disease activity, with an 86% median reduction approaching normal levels. Additionally, patients showed continued improvement in neurodevelopmental function, and many were able to discontinue standard-of-care intravenous enzyme replacement therapy (ERT) or remain ERT-naïve.
REGENXBIO plans to file a Biologics License Application (BLA) in 2024 using the accelerated approval pathway. The company aims to leverage CSF levels of D2S6 as a surrogate endpoint for accelerated approval, with potential approval anticipated as early as 2025.
The success of the RGX-121 trial represents a significant breakthrough in addressing the unmet medical needs of MPS II patients, offering hope for improved outcomes and a better quality of life. With these promising results, REGENXBIO is poised to make a meaningful impact in the treatment landscape for Hunter syndrome.
