Rezolute (NASDAQ:RZLT) shares fell sharply today following the announcement that its Phase 3 sunRIZE study of ersodetug for congenital hyperinsulinism (HI) did not meet its primary endpoint.
The stock fell almost 90% to trade at $1.15 late morning on Thursday.
The sunRIZE trial evaluated ersodetug’s ability to reduce weekly hypoglycemia events in patients with congenital HI. At the highest dose of 10 mg/kg, patients experienced an approximate 45% reduction in hypoglycemia events, which was not statistically significant compared with a 40% reduction seen in the placebo group.
The study also missed its key secondary endpoint, assessing change in average daily percent time in hypoglycemia, with a 25% reduction at the top dose versus a roughly 5% increase in the placebo group.
Rezolute said that target drug concentrations were achieved across all age groups studied and that safety observations were generally favorable.
Two participants experienced serious hypersensitivity reactions leading to early discontinuation, and hypertrichosis was the most commonly reported adverse event, which the company described as mild and self-limiting.
“We are disappointed that the study did not demonstrate significant improvements in glucose-related endpoints relative to placebo as well as for the patients and families living with congenital HI who urgently need new treatment options,” Rezoluate’s chief medical officer Dr Brian Roberts said in a statement.
“We are conducting a thorough evaluation to gain a better understanding of the study outcomes, which will inform our path forward.”
The company intends to meet with the US Food and Drug Administration under its Breakthrough Therapy Designation to discuss the next steps for the program.
Rezolute’s Phase 3 upLIFT trial for tumor-related hyperinsulinism is ongoing, with topline results expected in the second half of 2026.