Rezolute announced on February 5 (U.S. time) that RZ358 (ersodetug), its investigational therapy for hypoglycemia caused by tumor-mediated hyperinsulinism, has received Breakthrough Therapy Designation (BTD) from the U.S. Food and Drug Administration (FDA).

The designation was based on clinical data, the mechanistic rationale for RZ358 in tumor-mediated hyperinsulinism, and meaningful treatment effects observed in real-world patients through an Expanded Access Program currently underway across the United States. Breakthrough Therapy Designation is intended to expedite development and regulatory review for drugs that demonstrate substantial improvement over existing therapies for serious or life-threatening conditions at an early clinical stage.

Nevan Charles Elam, CEO and Founder of Rezolute, stated:
“This designation represents formal recognition by the FDA of the therapeutic potential of ersodetug for a life-threatening condition. Ersodetug can provide clinical benefit when persistent hypoglycemia cannot be effectively managed with standard therapies or when hypoglycemia interferes with surgery or other cancer treatments.”

He added:
“Ersodetug has a unique mechanism of action that can address multiple forms of hyperinsulinism, and we have observed successful treatment outcomes in tumor-mediated hyperinsulinism patients over the past two years.”
Rezolute plans to initiate a registrational study of RZ358 (ersodetug) in patients with tumor-mediated hyperinsulinism in mid-2025 and expects to announce topline data in the second half of 2026. In parallel, the company will engage with the FDA to discuss data requirements for a Biologics License Application (BLA) submission for this indication, leveraging the Breakthrough Therapy Designation.

Earlier this year, RZ358 also received Breakthrough Therapy Designation for the treatment of hypoglycemia caused by congenital hyperinsulinism. A global Phase 3 trial for this indication is currently underway in more than 12 countries.
Rezolute is a U.S.-based biotech company developing targeted therapies for rare metabolic diseases, including RZ358 for hyperinsulinism and RZ402, an oral therapy for diabetic macular edema. RZ358 is in Phase 3 trials for two indications: congenital hyperinsulinism and tumor-mediated hyperinsulinism. Handok holds commercialization rights for RZ358 and RZ402 in Korea and continues to collaborate with Rezolute throughout the development process.