For the first time since 2006, families dealing with Hunter syndrome have a genuinely new option. In March 2026, the FDA granted accelerated approval to Avlayah, a drug that crosses the blood-brain barrier and targets both the physical and neurological symptoms of MPS II, a rare genetic disease that primarily affects boys. Unlike the previous standard treatment, which only addressed physical symptoms, Avlayah goes after the brain component that families have long feared most.
The results so far come from real families. Atlas Neuerburg, who is nearly four, joined a clinical trial and has shown no further decline in more than two years. Cole Stephens, 15, received his first infusion in May 2026, and his mother Kim, who also serves as executive director of the Muenzer MPS Research and Treatment Center, says his focus has improved. Dr. Joseph Muenzer, a pediatric geneticist at UNC Health, describes the drug as a life changer for the MPS II community.
The financial picture is more complicated. Avlayah lists at $5,200 per vial in the U.S., with total costs varying by patient weight and insurance coverage. For families already stretched by years of care, that number matters as much as the science. The question now is how quickly access catches up with hope.
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