A late-stage trial for an experimental Angelman syndrome drug came back negative this week, dealing a major blow to patients and to the company behind it. Late-stage, in clinical testing, means the final round of human trials a medicine must complete before the maker can ask regulators to approve it for public use. Ultragenyx, which developed the drug, announced the outcome.
Angelman syndrome is a rare genetic disease. It causes severe developmental delays, and families living with it have had few treatment options available to them. The trial that just failed was testing whether a genetic medicine could change that.
It could not. Experts who study the disease say there is still reason to expect similar experimental therapies might succeed. The key word is similar: other drugs targeting the same biology are now in testing, and those trials have not yet concluded.
Mark Zylka, an Angelman researcher at the University of North Carolina, said the result does not, in his view, reflect on those other trials. He said he would not interpret a single failed trial as evidence that the general mechanism being tested is wrong. A mechanism, in this context, is the biological process a drug is designed to act on. The fact that Ultragenyx's drug could not act on it successfully does not mean another drug cannot.
The stakes of getting this right extend beyond Angelman syndrome. Experts said progress in this area could potentially open a path for genetic medicines in other neurological conditions, with the goal of restoring skills including cognition and communication in patients with intellectual disabilities. Whether that happens depends on results that have not come in yet.
For now, the data from this week settles one specific question: Ultragenyx's drug did not work in its late-stage trial. The question of whether the mechanism it relied on can be made to work remains, in Zylka's assessment, open.