After joining the study, your eligibility will be evaluated by a multidisciplinary team led by the Principal Investigator, which includes an oncologist to ensure you are appropriate for this clinical trial.

You must be at least 18 years of age and have a clinical diagnosis of tumor-associated hyperinsulinism (tHI). This is a condition where tumors cause excessive insulin production leading to low blood sugar levels (hypoglycemia).

To qualify, you must be experiencing an average of at least 3 hypoglycemic events per week with blood glucose below 54 mg/dL (3 mmol/L) or events requiring assistance due to altered mental or physical status.

You will be randomly assigned to receive either ersodetug (also known as RZ358, an anti-insulin receptor human monoclonal antibody) or a placebo (an inactive solution that looks identical to the medication).

The study is double-blind, meaning neither you nor the study doctor will know which treatment you are receiving.

You will receive the study medication (ersodetug or placebo) through intravenous (IV) infusion as an addition to your standard of care therapy for hypoglycemia.

The medication is provided in a sterile solution in a glass vial containing at least 1.0 mL of liquid.

The treatment will continue for approximately 8 weeks during the main (pivotal) treatment period.

Throughout the study, you will need to monitor your blood glucose levels using self-monitoring of blood glucose (SMBG) devices.

You will also be monitored with continuous glucose monitoring (CGM) during certain periods of the study to track your blood sugar levels continuously.

The study team will track how many hypoglycemic events (low blood sugar episodes) you experience each week compared to before starting treatment.

If you are hospitalized and requiring IV glucose infusion, the study will monitor changes in your glucose infusion rate.

The team will track how much the infusion rate can be reduced while maintaining safe blood sugar levels.

They will also measure the time it takes to completely wean you off IV glucose administration after starting the study medication.

Throughout the study, you will undergo various safety assessments including:

Blood tests (clinical laboratory measurements)

Electrocardiograms (ECGs) to monitor heart activity

Hepatic ultrasound to check your liver

Vital sign measurements and physical examinations

Immunogenicity assessments to check if your body develops antibodies against the study drug

After completing the main 8-week treatment period, you may be eligible to continue in an open-label extension (OLE) phase.

During this extension, all participants receive the active medication (ersodetug) to evaluate its long-term safety and effectiveness.

The extension will also assess changes in your standard of care medications for hypoglycemia over time.

The study is expected to run until September 2025, with final results available by September 2030.

Throughout the study and for 3 months after receiving your last dose, you must use effective contraception methods if you are of childbearing potential or have a partner who is.

Your participation requires an estimated minimum life expectancy of at least 3 months and an ECOG performance status of 2 or better (able to care for yourself with limited ability to work).