Rezolute, Inc. reported that its Phase 3 sunRIZE study of the monoclonal antibody ersodetug in congenital hyperinsulinism failed to meet the primary endpoint of reducing weekly hypoglycemia events and the key secondary endpoint of decreasing time spent in hypoglycemia. The 63‑patient, multinational trial showed a 45 % reduction in hypoglycemia events at the 10 mg/kg dose, statistically indistinguishable from the 40 % improvement observed in the placebo arm. The secondary endpoint, a 25 % reduction in time in hypoglycemia, also fell short, with a 5 % increase in the placebo group.
The failure is attributed to a combination of patient variability and a pronounced placebo effect that narrowed the difference between treatment and control. Management noted that the study design, while robust, may not have fully captured the heterogeneity of congenital hyperinsulinism presentations. CEO Nevan Elam described the outcome as “a disappointment that underscores the complexity of treating this rare disease,” while Chief Medical Officer Brian Roberts added that the data “provide valuable insights that will inform future trial design.”
Financially, the setback tightens Rezolute’s cash runway. The company reported a net loss of $18.9 million for Q3 2025, up from $17.1 million a year earlier, and a $24.4 million loss for Q4 2025, compared with $23.0 million in Q4 2024. Cash and investments stood at $150 million as of September 30, 2025, and $167.9 million as of June 30, 2025. The company’s guidance of roughly 23 months of runway now faces increased pressure as the next pivotal readout is not expected until the second half of 2026.
Rezolute’s Breakthrough Therapy designation for ersodetug in tumor hyperinsulinism remains in place, allowing for expedited FDA review. The company will meet with the FDA to discuss next steps based on the sunRIZE data. In addition, several securities‑class‑action firms have opened investigations into the company’s disclosures, reflecting heightened scrutiny over the trial’s outcome. The upLIFT study—an FDA‑agreed single‑arm, open‑label trial of as few as 16 patients—continues as the sole remaining pathway to potential approval for the tumor indication.
Looking ahead, Rezolute’s focus has shifted entirely to the upLIFT study, with topline results expected in the second half of 2026. The company’s ability to navigate the remaining regulatory hurdles and demonstrate clinical benefit in this smaller, streamlined trial will be critical to its long‑term viability. The sunRIZE failure has amplified the risk profile, but the Breakthrough Therapy designation and the company’s ongoing efforts to refine trial design may mitigate some of the uncertainty surrounding the tumor hyperinsulinism program.
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