Rezolute, Inc. announced results from a preclinical pharmacology study that validate the potential for its lead clinical compound, RZ358, to treat individuals with non-islet cell tumors (NICTs) that have uncontrolled hypoglycemia. Tumor hyperinsulinism (HI) may be caused by a variety of different tumor types, resulting in islet cell tumor hypoglycemia (ICTH) and NICTH. The Company previously reported on the successful use of RZ358 under its Expanded Access Program (EAP) to treat patients with insulin-producing pancreatic islet cell tumors (ICTs), or insulinomas, causing severe and uncontrolled hypoglycemia.

The therapeutic potential of RZ358 in this setting was anticipated given that ICTH is mediated by insulin and that RZ358 is known to work at the insulin receptor to decrease excess insulin binding and activity. However, it was unknown if RZ358 would have utility in NICTH where hyperinsulinism is mediated by hormones such as insulin-like growth factor-2 (IGF-2) or its variants, which likewise cause hypoglycemia by binding to and activating the insulin receptor. To test this, the Company recently completed in vitro pharmacology studies to evaluate the impact of clinically relevant concentrations of RZ358 on insulin receptor activation by IGF-2, compared to insulin.

This was tested at the relative concentrations of each ligand that activate the insulin receptor and are physiologically relevant in tumor HI caused by ICTH and NICTH, respectively. These experiments successfully demonstrated the ability of RZ358 to similarly blunt both IGF-2 and insulin-mediated insulin-receptor signaling, at levels of these ligands that are disease-relevant in humans. The Company recently reported on its successful interaction with the U.S. Food and Drug Administration (FDA) in January 2024 regarding the potential to initiate a single registrational study in patients with hypoglycemia due to tumor HI.

The Company will continue to evaluate the feasibility of a development program in this indication, with the possibility of including both ICTH and NICTH patients. The inclusion of NICTH patients in a potential addressable market for RZ358 in tumor HI would more than double the population. The Company is also currently evaluating RZ358 in a Phase 3 clinical trial in congenital HI, which is a rare pediatric condition where, similar to ICTH, children overproduce insulin creating a dangerous hypoglycemic state.