Rezolute, a U.S. biotech venture affiliated with Handok, announced on December 3rd that its investigational drug 'RZ358 (Ersodetug)' has been designated as an orphan drug by the U.S. Food and Drug Administration (FDA) for the treatment of hypoglycemia due to tumor-induced hyperinsulinism.

The FDA's orphan drug designation is a program designed to encourage the development of treatments for rare diseases. Drugs designated as orphan drugs receive benefits such as seven years of market exclusivity and eligibility for expedited approval pathways, which can shorten the clinical development timeline.

Dr. Susan Stewart, JD, Chief Regulatory Officer of Rezolute, stated, "This orphan drug designation by the FDA signifies the serious unmet need for patients with tumor-induced hyperinsulinism and demonstrates the potential benefits that Ersodetug can offer." She added, "Direct treatment of hypoglycemia is necessary not only to prevent severe side effects and improve patients' quality of life but also to enable patients to continue their cancer treatment. We are very pleased that the FDA designation allows us to continue developing a potential universal treatment for hypoglycemia caused by all forms of hyperinsulinism."

Rezolute's 'RZ358' is a monoclonal antibody that acts on specific sites of the insulin receptor. It has shown therapeutic effects in various conditions characterized by excessive insulin and hypoglycemia, such as congenital hyperinsulinism and tumor-induced hypoglycemia, and additional indications are being considered. The Phase 3 clinical trial for tumor-induced hypoglycemia is expected to begin patient enrollment in the first half of 2025. Additionally, the ongoing Phase 3 clinical trial for congenital hyperinsulinism is expected to yield topline results in the second half of 2025.

In October 2023, Rezolute announced a case of a patient with refractory hypoglycemia due to metastatic insulinoma treated with 'RZ358' through the Expanded Access Program (EAP). The EAP is a program that provides humanitarian support by expanding access to investigational drugs in the pre-approval clinical trial stage. Since then, several additional patients have been successfully treated as part of the EAP.

'RZ358' was previously designated as a Rare Pediatric Disease (RPD) drug by the FDA in 2020. In 2023, it received Priority Medicines (PRIME) status from the European Medicines Agency (EMA) for the treatment of congenital hyperinsulinism, and in January 2024, it was designated as an Innovative Medicine by the UK's Medicines and Healthcare products Regulatory Agency (MHRA).

Rezolute is a biotech venture developing targeted therapies for rare and metabolic diseases, including 'RZ358' for congenital hyperinsulinism and 'RZ402' for diabetic macular edema. Handok holds the commercialization rights for 'RZ358' and 'RZ402' in Korea and continues to collaborate with Rezolute on their development.