Neurocrine Biosciences plans to conduct a new study in 2027 to examine dosing and safety of its Prader-Willi syndrome treatment, Vykat XR, in patients with complex medical conditions. The announcement follows another reported death involving a patient who received the drug and questions from analysts about its safety during the company’s third-quarter earnings call on Monday.
The latest reported fatality brings the number of deaths reported among Vykat recipients to eight. Clinicians and patient advocates have raised concerns about serious adverse events in patients who received the treatment. However, these events have not been definitively linked to the drug.
Safety Concerns Surrounding Vykat
Vykat was approved in 2025 for Prader-Willi syndrome, a rare disorder associated with an insatiable desire to eat and a slow metabolism that can contribute to significant weight gain. The condition can also cause cognitive disabilities and behavioral challenges. Before the drug’s approval, patients had few treatment options.
Neurocrine acquired Vykat in April through its $2.9 billion acquisition of Soleno Therapeutics. Since then, reports of serious medical events among patients who received the treatment have drawn attention from clinicians and members of the Prader-Willi community.
Clinicians have raised concerns about seven deaths and more than 100 serious adverse events among Vykat recipients. The latest reported death increases the number of fatalities to eight. Most reported events involved edema, respiratory complications, or cardiac problems.
The most serious incidents occurred among patients with complex medical conditions, those taking other medications and individuals with pre-existing obesity. Clinicians have specifically warned prescribers about potential risks for patients with obesity, severe breathing difficulties, underlying heart problems and other medical conditions.
Although the reported events have not been definitively attributed to Vykat, clinicians have called attention to the potential risks in patients with complex health needs.
Neurocrine Defends Its Safety Guidance
During Monday’s third-quarter earnings call, analysts questioned Neurocrine about reports of serious adverse events and a recent letter from a clinician warning about potential safety risks associated with the treatment.
The company reiterated its confidence in the drug’s safety profile and emphasized the importance of appropriate patient selection and monitoring.
“We are confident in the benefit-risk profile of Vykat XR and believe the FDA-approved label provides clear guidance on how to use the medicine safely and effectively in the indicated patient population,” a Neurocrine spokesperson told BioSpace in a Monday evening statement.
The company also said it would continue monitoring safety, evaluating available information and working with the FDA as clinical and real-world experience with Vykat grows. Executives maintained that the existing prescribing label provides guidance on the potential risks associated with the treatment.
Planned Study and Sales Outlook
The new study, planned for 2027, will examine dosing and safety in patients with Prader-Willi syndrome who have complex health issues. Neurocrine intends to build additional evidence to support understanding of the drug’s safety profile among prescribers, patients and advocates.
William Blair clarified in an analyst note that the study was not requested by the FDA, despite the company’s collaboration with the agency.
Vykat generated $107 million in revenue during the third quarter, contributing to Neurocrine’s total revenue of $1.1 billion.
However, BMO Capital Markets warned that recent safety concerns and reported deaths could lead to more patients discontinuing treatment in the fourth quarter of 2026 and early 2027. The firm expects further studies to help establish the drug’s safety and appropriate dose titration, while anticipating that treatment continuation could be affected until additional evidence becomes available.
Neurocrine Responds to Vykat Safety Concerns With New Study
Neurocrine Biosciences is planning a new safety study for Vykat XR following reports of patient deaths and serious adverse events among people treated for Prader-Willi syndrome. The planned study is expected to examine dosing and safety in patients with complex health conditions. BioSpace
Vykat XR is used to treat hyperphagia, or the intense and persistent feeling of hunger associated with Prader-Willi syndrome. Reports submitted to the FDA have raised concerns about serious adverse events, including edema, respiratory complications, and cardiac issues. However, these reports do not establish that Vykat directly caused the reported deaths. STAT
Neurocrine has continued to support the benefit-risk profile of Vykat XR while emphasizing the importance of appropriate patient selection and monitoring. The company plans to explore whether different dosing approaches and additional safety measures could help address risks in patients with more complex medical conditions. BioSpace
