Rezolute, Inc. (NASDAQ:RZLT) ("Rezolute" or the "Company"), a late-stage rare disease company focused on treating hypoglycemia caused by all forms of hyperinsulinism (HI), today announced outcomes from an in-person Type B meeting with the U.S. Food and Drug Administration (FDA) held on March 17, 2026, related to sunRIZE, a Phase 3, multicenter, double-blind, randomized, placebo-controlled safety and efficacy study of ersodetug for the treatment of congenital HI.   

In December 2025, the Company reported that sunRIZE 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, which the Company believes was a result of a pronounced study effect. 

Although consistent and clinically significant improvements in time in hypoglycemia by continuous glucose monitoring (CGM) were observed compared to placebo over the course of the entire pivotal treatment period, nominal statistical significance was not achieved in this key secondary endpoint at the pre-specified Week 24 end-of-treatment period.  

During the meeting with FDA, the Company presented summary results from sunRIZE including: (i) information to support the Company's belief that the primary endpoint was confounded as a result of behavioral factors; (ii) evidence of pharmacologic activity, as target therapeutic drug concentrations were achieved in both treatment groups with highly sensitive biomarker responses of decreased insulin cell signaling; (iii) consistent improvements compared to placebo in time in hypoglycemia and a variety of other CGM-based glycemic endpoints; and (iv) preliminary favorable observations from the ongoing open-label extension portion of the study (OLE), which indicate continued improvement in glycemic parameters in the ersodetug treatment arms and placebo roll-over, concurrent with a notable reduction of other background standard-of-care therapies.   

FDA acknowledged the challenges posed by the potential impact of varied behavioral factors on clinical trials in this heterogeneous patient population, including the associated limitations of self-monitored blood glucose (SMBG) based metrics in measuring hypoglycemia in congenital HI. 

The Company believes that the unblinded nature of self-monitored glucose necessary for patient standard of care, together with perceptions of treatment assignment, may have led to divergent behaviors between treatment groups during the study, which may have impacted the measurement of hypoglycemia by SMBG.

While acknowledging these challenges, the agency reiterated the expectation for adequate and well-controlled studies and outcomes as the standard for evaluating substantial evidence of efficacy criteria as the basis for approving new therapies.

The agency and the Company then discussed summary outcomes from various CGM-based glycemic endpoints and preliminary observations from the OLE. These and other outcomes from the pivotal portion of the sunRIZE trial will be shared by oral presentation at an upcoming scientific conference.

As a next step for the program, FDA encouraged the Company to submit study reports and analysis datasets for the agency's independent evaluation. Following that review, the Company believes that a determination may be made whether there is sufficient evidence to support the submission of a marketing application for sunRIZE or if additional information is required. The Company expects to have an update on the program in the second half of 2026.