Announcement • Sep 09

Rezolute Provides Update on FDA Review of Its Phase 3 Sunrize Study Results in Congenital Hyperinsulinism

Rezolute provided an update on the status of the ongoing U.S. Food and Drug Administration review of data from the Company’s Phase 3 sunRIZE study of ersodetug for the treatment of hypoglycemia due to congenital hyperinsulinism. Data from the Phase 3 sunRIZE study remains under review by FDA. The OLE Phase of the study is ongoing, with a high participation rate and several indicators of improved glycemic control, including a notable reduction in the use of background standard of care therapies. Enrollment continues in the Phase 3 upLIFT study in tumor hyperinsulinism and the Company remains on track to report topline results before the end of 2026. SunRIZE, a Phase 3, multicenter, double-blind, randomized, placebo-controlled safety and efficacy study of ersodetug for the treatment of congenital hyperinsulinism, demonstrated reductions from baseline in hypoglycemia events, but the study did not meet its primary endpoint because the reductions were not statistically significant compared to placebo. At a March 2026 Type B meeting with FDA, the Agency acknowledged the challenges posed by behavioral factors in clinical trials in this patient population, including limitations associated with self-monitored blood glucose based measures of hypoglycemia. At the meeting, the Agency requested that the Company provide additional study data for its independent review and in June 2026, the Company submitted the source and analysis datasets and summary results from a substantial number of pre-specified, post-hoc, and sensitivity analyses with a focus on continuous glucose monitoring based glucose outcomes from the pivotal portion of the study. The Company believes that from its perspective the data submitted for FDA’s review includes potential data of target engagement, pharmacologic activity, and glycemic improvement. Specifically, there were consistent glycemic improvements in the treatment arms compared with placebo across multiple continuous glucose monitoring based outcomes at both ersodetug dose levels, including but not limited to 50% or greater reductions in both average daily percent time in hypoglycemia and average weekly hypoglycemia events. In recent interactions with the Company, the Agency reiterated that it is still reviewing the submission for purposes of evaluating a potential regulatory path forward for ersodetug in congenital hyperinsulinism. Given that FDA’s review is being conducted outside of the customary formal meeting process, there is no specific timeline regarding when feedback will be received or alignment on potential next steps will be reached. The Company will continue to await feedback and reserves the ability to request a formal meeting under a regulatory timeline, as needed. The open-label extension phase of the study is ongoing, with a continued high retention rate, equating to a cumulative ersodetug treatment duration in sunRIZE ranging from approximately nine months to well over two years. This, along with continued glycemic monitoring and a notable reduction in the use of background standard of care therapies, potentially indicate continued glycemic and clinical benefit with ersodetug in longer-term use. Rezolute continues to recruit patients in its Phase 3 upLIFT study of ersodetug for tumor hyperinsulinism and remains on track to report topline results before the end of 2026. The Phase 3 sunRIZE study (RZ358-301) was a multi-center, randomized, double-blind, placebo-controlled, parallel arm study designed to evaluate the efficacy and safety of ersodetug in patients with congenital hyperinsulinism, ages 3 months to 45 years old, who were experiencing continued hypoglycemia on currently available standard of care. Eligible participants were randomized to one of three treatment arms to receive either ersodetug (5 or 10 mg/kg) or matched placebo-control as add on to existing standard of care. Study drug was administered every other week during an initial loading phase, and then every 4 weeks during the 6-month controlled pivotal treatment period. Following the pivotal treatment phase of the study, participants could roll-over into an optional open-label extension phase to continue to receive ersodetug. The study enrolled 63 participants in more than a dozen countries around the world, inclusive of U.S. patients. The primary and key secondary efficacy endpoints in the study were the change from baseline in the average number of hypoglycemia events per week and the average percent time in hypoglycemia, respectively, over six months of treatment. In December 2025, the Company announced that the sunRIZE study did not meet its primary or key secondary endpoints. Although statistical significance for the secondary endpoint (% time in hypoglycemia by continuous glucose monitoring) was not achieved at the Week 24/End of Treatment evaluation window, larger and often nominally statistically significant glycemic improvements compared to placebo were consistently observed throughout the maintenance dosing phase of the study, across time and numerous pre-specified and post-hoc continuous glucose monitoring based endpoints. As a next step for the program, the U.S. Food and Drug Administration encouraged Rezolute to submit comprehensive analysis datasets and summary outcomes for the Agency’s independent evaluation. Ersodetug is a fully human monoclonal antibody that binds allosterically to the insulin receptor to decrease receptor over-activation by insulin and related substances (such as IGF-2) in the setting of hyperinsulinism, thereby improving hypoglycemia. Because ersodetug acts downstream from pancreatic insulin or paraneoplastic IGF-2 secretion and from entero-incretin pathways, it has the potential to be universally effective at treating refractory hypoglycemia due to any form of hyperinsulinism, including congenital hyperinsulinism, tumor hyperinsulinism (insulinoma, non-islet cell tumors) or bariatric/non-bariatric gastrointestinal surgery hypoglycemia. Ersodetug for the treatment of hyperinsulinism is investigational. Statements about safety and efficacy have not been approved by any health authority.

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