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Study on RZ358 for Treating Congenital Hyperinsulinism in Patients

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What is this trial about?

A plain-language summary of the goals, design and what participants do

Congenital Hyperinsulinism is a rare condition in which the pancreas releases too much insulin, leading to frequent episodes of low blood sugar, also called hypoglycemia. The study tests a medication called RZ358, which is an anti-(insulin receptor) human monoclonal antibody given through an IV infusion, and compares it with a placebo that looks the same but contains no active drug.

The main goal of the research is to find out whether RZ358 can lower the number of hypoglycemia events over a period of about six months. Participants are randomly assigned to receive either the study drug or the placebo, and neither the participants nor the study staff know which treatment is given. During the study, blood sugar levels are checked at home using a finger‑stick method called self‑monitored blood glucose and also with a small sensor that continuously records glucose levels, known as continuous glucose monitoring. The schedule includes regular visits for infusions and safety checks.

In addition to tracking blood sugar, the trial monitors participants for any side effects, changes in vital signs, and overall health through routine lab tests and physical examinations. The study follows each person for the full treatment period to evaluate both the effectiveness of the drug in preventing low blood sugar and its safety profile.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, you will be asked to provide written informed consent. This means you agree to participate after understanding the study's purpose and procedures.

    If applicable, you may also need to provide assent, which is a form of agreement for participants who are minors.

  2. Step 2

    Initial assessment

    You will undergo an initial assessment to confirm your eligibility. This includes verifying your age, which should be between 3 months and 45 years.

    A clinical diagnosis of congenital hyperinsulinism will be confirmed, and your previous treatment history will be reviewed to ensure you have not achieved adequate glycemic control with standard therapies.

  3. Step 3

    Screening tests

    Screening tests will be conducted, including monitoring your blood sugar levels to confirm frequent hypoglycemia events.

    A hepatic ultrasound will be performed to check for any significant liver issues.

  4. Step 4

    Pregnancy test and contraception

    If you are a female of childbearing potential, a pregnancy test will be required before starting the study.

    You will need to agree to use effective contraceptive methods during the study and for at least 3 months after the last dose of the study drug.

  5. Step 5

    Treatment phase

    You will be randomly assigned to receive either the study drug, RZ358, or a placebo. This is a double-blind study, meaning neither you nor the researchers will know which you are receiving.

    The medication will be administered as an intravenous infusion, which means it will be given directly into your vein. The treatment will last for 24 weeks.

  6. Step 6

    Monitoring and assessments

    Throughout the study, your blood sugar levels will be regularly monitored using self-monitored blood glucose (SMBG) and continuous glucose monitoring (CGM) devices.

    You will also undergo regular safety assessments, including laboratory tests, physical exams, and possibly additional ultrasounds.

  7. Step 7

    End of treatment

    After 24 weeks, the treatment phase will conclude. You will have a final assessment to evaluate the effects of the treatment on your blood sugar levels and overall health.

    You may be asked to continue monitoring your blood sugar levels for a short period after the study ends.

Who can join the trial?

9 criteria

  • Provide written informed consent, and if applicable, assent, before any study-specific procedures are performed.
  • Be aged at least 3 months (corrected for gestational age for children under 9 months) and no older than 45 years at the time of screening.
  • Have a confirmed clinical diagnosis of congenital hyperinsulinism (HI), with or without a known genetic cause identified through testing.
  • Have not achieved adequate blood sugar control despite trying standard medical treatments available locally, such as diazoxide and somatostatin analogs (SSAs), as judged by the study doctor.
  • Experience at least 3 episodes of hypoglycemia (low blood sugar, less than 70 mg/dL or 3.9 mmol/L) per week, as measured by self-monitoring or as evaluated by the study doctor. Additionally, have an average daily time with low blood sugar of at least 8% during the monitored screening period.
  • Have a liver ultrasound at screening that shows no significant issues, such as large or obstructive gallstones or signs of a liver condition called peliosis hepatitis, as judged by the study doctor.
  • For female participants who can become pregnant, have a negative pregnancy test within 7 days before starting the study treatment.
  • For female participants who can become pregnant, agree to use highly effective birth control methods to prevent pregnancy during the study and for at least 3 months after the last dose of the study drug. If using hormonal birth control, it is recommended to also use a second method, like a barrier method (e.g., condoms).
  • For sexually active male participants, agree to use contraceptive measures, such as condoms, during the study and for at least 3 months after the last dose of the study drug. Additionally, agree not to donate sperm during this period.

Who cannot join the trial?

10 criteria

  • Patients with other serious health conditions that might interfere with the study.
  • Patients who are pregnant or breastfeeding.
  • Patients who have participated in another clinical trial recently.
  • Patients who have allergies to the study medication or its ingredients.
  • Patients who are unable to follow the study procedures or instructions.
  • Patients with a history of drug or alcohol abuse.
  • Patients with certain heart conditions.
  • Patients with severe kidney or liver problems.
  • Patients who are taking medications that might interfere with the study drug.
  • Patients with a history of certain mental health conditions.
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Investigated drugs

RZ358 is a medication being studied for its potential to help people with congenital hyperinsulinism, a condition where the body produces too much insulin, leading to low blood sugar levels. This medication is designed to help manage blood sugar levels by reducing the effects of excess insulin in the body. The goal of using RZ358 in this trial is to see if it can help prevent episodes of low blood sugar, making it easier for patients to maintain stable blood sugar levels over a period of 24 weeks.

What is already known about the treatment

RZ358 – RZ358 is administered intravenously, meaning it is given directly into a vein through an injection. It is currently being studied in clinical trials and is not yet widely available in medical practice. The main use of RZ358 is to treat hypoglycemia, which is low blood sugar, in patients with congenital hyperinsulinism, a condition where the body produces too much insulin. At the molecular level, RZ358 works by blocking the effects of insulin on its receptor, helping to prevent dangerously low blood sugar levels. It is classified as an anti-hypoglycemic agent, which means it helps to prevent or treat low blood sugar.

Investigated diseases

Hypoglycemia associated with congenital hyperinsulinism – This condition is characterized by low blood sugar levels due to excessive insulin production from the pancreas. It is a genetic disorder where the insulin-producing cells in the pancreas release too much insulin, even when blood sugar levels are low. The disease often presents in infancy or early childhood, leading to symptoms such as irritability, lethargy, and seizures due to low blood sugar. Over time, if not managed, it can cause developmental delays and neurological issues. The frequency and severity of hypoglycemic episodes can vary, and they may occur spontaneously or be triggered by fasting or illness. The condition requires careful monitoring of blood sugar levels to prevent episodes of hypoglycemia.
Trial detailsLast updated 21 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-503240-13-00Protocol codeRZ358-301Estimated enrolment84 patientsSponsorRezolute Inc.

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