Rezolute Provides Update on FDA Review of its Phase 3 sunRIZE Study Results in Congenital Hyperinsulinism
FDA continues an open-ended review of additional Phase 3 sunRIZE data while Rezolute advances its tumor HI Phase 3 study toward 2026 results.
Rhea-AI Summary
Rezolute (RZLT) reported that the U.S. FDA is continuing its review of extensive Phase 3 sunRIZE data for ersodetug in congenital hyperinsulinism (HI), with no defined timeline for regulatory feedback.
The pivotal sunRIZE trial previously showed reductions from baseline in hypoglycemia events but did not meet its primary or key secondary endpoints versus placebo. At FDA’s request, Rezolute submitted source and analysis datasets, including numerous pre‑specified, post‑hoc and sensitivity analyses focused on continuous glucose monitoring (CGM) outcomes. The company believes these data show consistent glycemic improvements in ersodetug arms, including ≥50% reductions in average daily percent time in hypoglycemia and average weekly hypoglycemia events.
The sunRIZE open‑label extension phase continues with high retention and reduced use of background standard of care therapies. Enrollment also continues in the Phase 3 upLIFT study in tumor HI, with topline results expected before the end of 2026.
Positive
- CGM-based outcomes showed ≥50% reductions in average daily percent time in hypoglycemia and weekly hypoglycemia events versus placebo arms.
- FDA requested and is still conducting an independent review of extensive Phase 3 sunRIZE datasets for a potential regulatory path.
- The sunRIZE open-label extension shows high retention and reduced use of background standard of care therapies over up to two-plus years.
- The Phase 3 upLIFT trial in tumor HI continues enrollment, with topline results expected before the end of 2026.
Negative
- The pivotal sunRIZE Phase 3 trial did not meet its primary or key secondary endpoints versus placebo.
- FDA’s review is occurring outside customary formal meeting processes, with no specific timeline for feedback or next steps.
- Ersodetug remains an investigational therapy, with no safety or efficacy claims approved by any health authority.
Details
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Key Figures
- CGM-based reductions
- 50% or greater
- Average daily percent time in hypoglycemia and average weekly hypoglycemia events
- Study enrollment
- 63 participants
- Phase 3 sunRIZE study
- Pivotal treatment period
- 6 months
- Controlled Phase 3 sunRIZE treatment period
- upLIFT topline timing
- Before the end of 2026
- Phase 3 tumor HI study
Previous Clinical trial Reports
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SunRIZE missed endpoints but showed pharmacologic activity and ongoing OLE participation
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Expanded sunRIZE analyses reported consistent CGM-based glycemic improvements versus placebo
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SunRIZE failed its primary and key secondary endpoints in congenital hyperinsulinism
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Key Terms
type b meeting regulatory
self-monitored blood glucose medical
continuous glucose monitoring medical
open-label extension medical
AI-generated analysis. How Rhea-AI works. Not financial advice.
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 HI and the Company remains on track to report topline results before the end of 2026
REDWOOD CITY, Calif., Sept. 09, 2026 (GLOBE NEWSWIRE) -- Rezolute, Inc. (Nasdaq: RZLT) (“Rezolute” or the “Company”), a late-stage ultra-rare disease company focused on treating refractory hypoglycemia caused by any form of hyperinsulinism (“HI”), today provided an update on the status of the ongoing U.S. Food and Drug Administration (“FDA” or “Agency”) review of data from the Company’s Phase 3 sunRIZE study of ersodetug for the treatment of hypoglycemia due to congenital HI.
As previously reported, sunRIZE, a Phase 3, multicenter, double-blind, randomized, placebo-controlled safety and efficacy study of ersodetug for the treatment of congenital HI, 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 (SMBG) 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 (CGM) 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 CGM-based outcomes at both ersodetug dose levels, including but not limited to
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 HI. 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 (OLE) 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.
“We appreciate FDA’s continued engagement and thorough review of the extensive body of data generated from the sunRIZE program,” said Nevan Charles Elam, Chief Executive Officer and Founder of Rezolute. “We remain committed to working with the Agency to determine a path forward for ersodetug in congenital HI and address the significant unmet needs of patients and families living with this serious, rare disease.”
Separately, Rezolute continues to recruit patients in its Phase 3 upLIFT study of ersodetug for tumor HI and remains on track to report topline results before the end of 2026.
About sunRIZE
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 (HI), ages 3 months to 45 years old, who were experiencing continued hypoglycemia on currently available standard of care (SOC). 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 SOC. 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 [“CGM”]) 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 CGM-based endpoints. As a next step for the program, the U.S. Food and Drug Administration (FDA) encouraged Rezolute to submit comprehensive analysis datasets and summary outcomes for the Agency’s independent evaluation.
About Ersodetug
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 (HI), 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 (HI), including congenital HI, tumor HI (insulinoma, non-islet cell tumors) or bariatric/non-bariatric gastrointestinal surgery hypoglycemia. Ersodetug for the treatment of HI is investigational. Statements about safety and efficacy have not been approved by any health authority.
About Rezolute, Inc.
Rezolute is a late-stage ultra-rare disease company focused on treating refractory hypoglycemia caused by any form of hyperinsulinism (HI). The Company’s antibody therapy, ersodetug, has been studied in clinical trials and used in real-world cases for the treatment of refractory hypoglycemia due to a variety of causes of HI. For more information, visit www.rezolutebio.com.
Forward-Looking Statements
This release, like many written and oral communications presented by Rezolute and our authorized officers, may contain certain forward-looking statements regarding our prospective performance and strategies within the meaning of Section 27A of the Securities Act and Section 21E of the Securities Exchange Act of 1934, as amended. We intend such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995 and are including this statement for purposes of said safe harbor provisions. Forward-looking statements, which are based on certain assumptions and describe future plans, strategies, and expectations of Rezolute, are generally identified by use of words such as "anticipate," "believe," "estimate," "expect," "intend," "plan," "project," "seek," "strive," "try," or future or conditional verbs such as "could," "may," "should," "will," "would," or similar expressions. These forward-looking statements include, but are not limited to, the potential efficacy of ersodetug in treating hypoglycemia as well as our ability to complete enrollment of the upLIFT study this year and announce topline results. Our ability to predict results or our plans or strategies is inherently uncertain. Notably, no assurance can be given that FDA will agree with the Company that there is evidence of clinically meaningful benefit observed in the sunRIZE study and accordingly the Agency could make the determination that the only path forward for the congenital HI indication is a new randomized control trial similar to sunRIZE. Should the Agency make such a determination, that would adversely impact the Company’s ability to further pursue that indication as well as the commercial potential for ersodetug. Actual results may differ materially from anticipated results. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this release. Except as required by applicable law or regulation, Rezolute undertakes no obligation to update these forward-looking statements to reflect events or circumstances that occur after the date on which such statements were made. Important factors that may cause such a difference include any other factors discussed in our filings with the SEC, including the Risk Factors contained in Rezolute’s Annual Report on Form 10-K and Quarterly Reports on Form 10-Q, which are available at the U.S. Securities and Exchange Commission’s website at www.sec.gov. You are urged to consider these factors carefully in evaluating the forward-looking statements in this release and are cautioned not to place undue reliance on such forward-looking statements, which are qualified in their entirety by this cautionary statement.
Rezolute Contacts:
Christen Baglaneas
cbaglaneas@rezolutebio.com
508-272-6717
Carrie McKim
cmckim@rezolutebio.com
336-608-9706
