Neurocrine Biosciences is defending the safety profile of Vykat XR after another patient death was reported in people taking the Prader-Willi syndrome therapy. The company confirmed the new death this week and told BioSpace it remains confident in the drug’s benefit-risk profile, while stressing appropriate monitoring and patient selection.
The event quickly became a focus of Neurocrine’s third-quarter earnings call on Monday afternoon, where analysts pressed executives on real-world safety reports and on a recent letter from a clinician warning about risks associated with the medicine. Neurocrine’s position was that the current FDA-approved label already provides clear guidance on how to use Vykat XR safely and effectively in the indicated population.
Vykat was approved for the rare disorder in 2025 and came to Neurocrine in April through the company’s $2.9 billion acquisition of Soleno Therapeutics. For Neurocrine, the issue is no longer just whether the product addresses a high unmet need in Prader-Willi syndrome, but whether safety management in routine practice can preserve persistence and confidence after launch.
The safety debate
Prader-Willi syndrome causes an insatiable desire to eat and a slow metabolism that together can lead to significant weight gain. The condition can also cause cognitive disabilities and behavioral challenges. Before Vykat was approved, patients had few options.
Clinicians and patient advocates have been raising concerns about serious safety events in patients who received the drug. BioSpace reported that clinicians warned about seven deaths and more than 100 serious adverse events before the latest case. The newest report would bring the number of deaths to eight. Most of the events were associated with edema, respiratory and cardiac complications.
Those incidents were reported most often in patients with complex medical issues, use of other medications or pre-existing obesity. The events have not been definitively linked to Vykat, clinicians have noted, and BioSpace also reported that patients with Prader-Willi have complex needs. Even so, the warnings have centered on heightened risk among patients with obesity, severe breathing issues, underlying heart problems and other conditions.
Neurocrine’s response has been to defend the label while acknowledging the need for close monitoring as clinical and real-world use expands. In its statement to BioSpace, the company said it continues to closely monitor safety, evaluate all available information and work with the FDA.
The commercial picture
The franchise remained commercially meaningful in the third quarter despite the controversy. Vykat generated $107 million in the period, contributing to Neurocrine’s total revenue of $1.1 billion.
Still, the market readthrough has become more cautious. William Blair said in a Tuesday morning note that Vykat’s franchise was resilient in the quarter and that Neurocrine remains committed to the benefits of the drug in the right patients with the right monitoring. BMO Capital Markets, by contrast, said recent concerns over product safety and patient deaths could lead to increased patient discontinuations in 4Q26 and early 2027, which could weigh on patient persistence until additional evidence clarifies optimal dosing and use.
What to watch
Neurocrine said it is planning a new study in 2027 to explore dosing and safety in patients with Prader-Willi who have complex health issues. William Blair said the company clarified on the earnings call that the study was not an FDA request, despite ongoing collaboration with the agency.
That distinction matters. A voluntary study suggests Neurocrine still has room to shape the evidence package itself, but it also signals that post-approval commercialization now depends on rebuilding confidence through narrower patient selection, better education and more data on higher-risk groups. For a rare disease product acquired at a multibillion-dollar price, that execution challenge may become as important as the original approval.
