A Carrboro mother has pulled in close with UNC researchers after watching her 15-year-old son lose basic skills to a devastating genetic disease. Over several years, Cole regressed, losing most of his spoken language by about age eight, and his mother says an investigational therapy in a clinical trial slowed that decline. She is now working directly with a UNC pediatric geneticist who leads trials that aim to deliver enzyme therapy into the brain.
As reported by CBS17, the boy, identified as 15‑year‑old Cole Mausolf of Carrboro, received investigational infusions through a clinical trial that his mother, Kim Stephens, says slowed his rate of decline. Stephens is now the executive director of the Muenzer MPS Research and Treatment Center and has relocated to Chapel Hill to be near care and trials, according to the report.
UNC research aims to reach the brain
The UNC School of Medicine and its Muenzer MPS Research and Treatment Center are testing an intravenous enzyme replacement designed to cross the blood–brain barrier and remove sugar‑waste buildup that damages brain and body cells, according to UNC Health. The center's director, Dr. Joseph Muenzer, served as lead investigator on the trial of tividenofusp alfa, an experimental treatment developed in collaboration with Denali Therapeutics.
Early trial data show biological impact
The phase 1–2 results published in the New England Journal of Medicine reported large reductions in the biomarker heparan sulfate in cerebrospinal fluid and urine, roughly 91% and 88% at the primary analysis, and noted that adaptive‑behavior scores stabilized or improved for many participants. The paper also observed that infusion‑related reactions were common but generally manageable, and that randomized studies are underway to confirm clinical benefit.
Small wins for families
For families, small improvements are everything. Stephens told CBS17 that she “miss[es] hearing his sweet voice” and that Cole lost most spoken words years ago, and the local report noted she measures his stability by whether he can complete a floor puzzle. Those modest markers, a few minutes of focused play or a retained phrase, can mean the difference between steady decline and a stretch of better function.
Regulatory timeline and next steps
Denali has said the FDA accepted a Biologics License Application for tividenofusp alfa and later extended the review, setting a revised PDUFA target date of April 5, 2026, per company filings and press materials. Separately, REGENXBIO's gene therapy candidate for MPS II, clemidsogene lanparvovec (RGX‑121), has been under priority review with a PDUFA target date of February 8, 2026, after the company provided additional 12‑month data during the review process.
What to watch
Researchers and advocates say the key question is whether brain‑penetrant therapies will change the disease’s natural history, especially when given early. Dr. Joseph Muenzer has said the drug could prevent progression if children are diagnosed and treated early, per UNC Health, and patient‑group information outlines how severe MPS II can be without central‑nervous‑system treatment, including respiratory, feeding and mobility decline in childhood, according to the MPS Society.
