Rezolute Shares Plunge After Phase III Trial Failure for Congenital Hyperinsulinism Drug

Rezolute’s stock dropped more than 80% following the failure of its Phase III sunRIZE trial for ersodetug, a monoclonal antibody targeting the insulin receptor for congenital hyperinsulinism (CHI). The trial did not meet its primary endpoint of reducing average weekly hypoglycemia events by self-monitored blood glucose, nor the key secondary endpoint assessing percent time in hypoglycemia via continuous glucose monitoring. While the high-dose cohort saw a 45% reduction in hypoglycemia events, placebo participants improved by 40%, making the difference statistically insignificant.

The 24-week trial tested 5mg and 10mg doses administered every other week initially, then every four weeks. Safety was generally favourable in both pediatric and adult patients.

Rezolute plans to discuss the results with the FDA under ersodetug’s breakthrough therapy designation to determine next steps. The therapy is also being evaluated in the Phase III upLIFT trial for tumour hyperinsulinism, with topline results expected in H2 2026.

18-12-2025