Concerns are escalating around Neurocrine Biosciences’ rare-disease drug Vykat XR for Prader-Willi syndrome after patient advocates and some external experts raised safety alarms in the wake of an open letter about the therapy. STAT reported that, since approval 18 months ago, Vykat has been linked in case reports to seven deaths and nearly 100 hospitalizations. Neurocrine-linked cases were reviewed by advocates and obtained by STAT through the Freedom of Information Act, but the reporting also emphasizes that submitted cases do not prove causality. Still, experts cited in the report said the evidence could be sufficient to conclude the therapy may be causing unacceptable harm. The unfolding response is significant for rare disease pharmacovigilance: it highlights how real-world signals can drive scrutiny even without definitive causal attribution, and it may influence what regulators demand next in post-marketing surveillance for high-impact but rare patient populations.