Paul Harmatz, MD, on Reducing D2S6 in Neuronopathic Hunter Syndrome With RGX-121 Gene Therapy

“It was really very important to see that it extends out 4 years and there was a dose response, the low dose has the least significant drop, the high dose has a drop that puts it very close to the normal range for D2S6in a group of normal individuals that we have spinal fluid, CSF fluid from and anything quantitative, and approximate where the patients participating have fallen in the spectrum of normal, attenuated and severe CSF measures. So, length of time, dose response, very excellent drop close to the normal range.”

REGENXBIO’s pivotal phase 1/2/3 CAMPSIITE clinical trial (NCT03566043) assessing RGX-121 in patients with severe neuronopathic central nervous disease in mucopolysaccharidosis type 2 (MPSII), also known as Hunter syndrome, has met its primary endpoint of reducing cerebrospinal fluid (CSF) levels of D2S6 compared with baseline (P = .00016).

Data from CAMPSIITE were presented by Paul Harmatz, MD, pediatric gastroenterologist and professor in residence at University of California at San Francisco, at the 2024 WORLDSymposium, held February 4-9, in San Diego, California.

CGTLive spoke with Harmatz to learn more about D2S6 as a biomarker for MPSII compared with the more commonly used heparin sulfate biomarker. He noted that D2S6 seems to be more sensitive to neuronopathic changes in MPSII and is thus a bespoke biomarker for brain disease activity. He touched on the dose response seen with RGX-121 and shared his excitement that the higher dose put children into the normal range of D2S6.

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REFERENCE

Harmatz P, Ficicioglu C, Giugliani R, et al. CAMPSIITE™ phase I/II/III: An interim clinical study update of RGX-121, an investigational gene therapy for the treatment of neuronopathic mucopolysaccharidosis type II (MPS II). Presented at: 2024 WORLDSymposium; February 4-9; San Diego, California. Abstract #135