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Study on the Safety and Effectiveness of Pozelimab and Cemdisiran for Adults with Paroxysmal Nocturnal Hemoglobinuria Not Recently Treated with Complement Inhibitors

Verified siteRegistered drugNo placebo
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What is this trial about?

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

This clinical trial is focused on studying a rare blood disease called Paroxysmal Nocturnal Hemoglobinuria (PNH). PNH is a condition where red blood cells break down too early, leading to various health issues. The study is testing a combination of two treatments, Pozelimab and Cemdisiran, to see how safe and effective they are for patients with PNH who have not recently received or have never received treatment with complement inhibitors, which are drugs that help prevent the breakdown of red blood cells.

The purpose of the study is to compare the effects of the combination therapy of Pozelimab and Cemdisiran with other treatments, such as Ravulizumab and Eculizumab, which are also used to treat PNH. The study will last for 26 weeks, during which participants will receive either the combination therapy or one of the other treatments. The study will monitor how well the treatments control the breakdown of red blood cells and whether they help avoid the need for blood transfusions.

Participants will be divided into two groups, known as cohorts. One group will receive the combination therapy and be compared to those receiving Ravulizumab, while the other group will be compared to those receiving Eculizumab. The study will assess the effects of the treatments by measuring levels of a substance called lactate dehydrogenase (LDH) in the blood, which indicates how much red blood cell breakdown is occurring. The study aims to provide valuable information on the safety and effectiveness of the new combination therapy for managing PNH.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial visit

    Upon joining the study, you will attend an initial visit. During this visit, your eligibility will be confirmed through tests, including high-sensitivity flow cytometry to check for paroxysmal nocturnal hemoglobinuria (PNH).

    You will be informed about the study procedures and asked to provide consent to participate. This visit will also include a review of your medical history and a physical examination.

  2. Step 2

    Treatment assignment

    You will be randomly assigned to one of two groups. One group will receive a combination of pozelimab and cemdisiran, while the other group will receive either ravulizumab or eculizumab.

    The assignment is random to ensure the study's scientific validity.

  3. Step 3

    Treatment administration

    If you are in the pozelimab and cemdisiran group, you will receive these medications as a solution for injection. The frequency and dosage will be explained to you by the study team.

    If you are in the ravulizumab or eculizumab group, you will receive these medications as a solution for infusion. The study team will provide details on the dosage and frequency.

  4. Step 4

    Regular monitoring

    Throughout the 26-week treatment period, you will have regular clinic visits to monitor your health and the effects of the treatment.

    These visits will include blood tests to measure lactate dehydrogenase (LDH) levels, which help assess the treatment's impact on hemolysis, a process where red blood cells break down.

  5. Step 5

    Follow-up visits

    After completing the treatment period, you will have follow-up visits to ensure your well-being and to gather additional data on the treatment's long-term effects.

    These visits will include assessments similar to those during the treatment period, such as blood tests and health evaluations.

Who can join the trial?

6 criteria

  • Must have a confirmed diagnosis of Paroxysmal Nocturnal Hemoglobinuria (PNH) through a special blood test called high-sensitivity flow cytometry.
  • Must have active PNH, which means experiencing one or more signs or symptoms related to PNH.
  • Must have a level of lactate dehydrogenase (LDH) that is at least twice the upper limit of normal (ULN) at the screening visit. LDH is an enzyme that can indicate cell damage when elevated.
  • Must be willing and able to attend clinic or remote visits and follow study-related procedures, including completing all required meningococcal vaccinations. These are vaccines to protect against certain types of bacterial infections.
  • Open to both male and female participants.
  • Participants must be within the specified age range for the study.

Who cannot join the trial?

2 criteria

  • Patients who have received a **complement inhibitor** treatment recently cannot participate. A complement inhibitor is a type of medication used to treat certain blood disorders.
  • Patients who are not **treatment-naive** for complement inhibitors are excluded. Treatment-naive means they have not been treated with this type of medication before.
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Investigated drugs

  • Pozelimab

    is a medication being studied for its ability to help patients with a condition called Paroxysmal Nocturnal Hemoglobinuria (PNH). PNH is a disease where red blood cells break down too easily, leading to various health problems. Pozelimab works by blocking a part of the immune system that is overactive in PNH, which can help reduce the breakdown of red blood cells.

  • Cemdisiran

    is another medication being tested in combination with Pozelimab for treating PNH. Like Pozelimab, Cemdisiran aims to control the overactive part of the immune system that causes red blood cells to break down. By using both medications together, the study hopes to see a better effect in managing the symptoms of PNH.

  • Ravulizumab

    is a medication already used to treat PNH. It helps prevent the breakdown of red blood cells by blocking the same part of the immune system that Pozelimab and Cemdisiran target. In this study, Ravulizumab is used as a comparison to see how well the new combination of Pozelimab and Cemdisiran works.

  • Eculizumab

    is another existing treatment for PNH. It also works by stopping the immune system from breaking down red blood cells too quickly. In the trial, Eculizumab is used to compare its effectiveness with the new combination of Pozelimab and Cemdisiran, to see if the new treatment offers any advantages.

What is already known about the treatment

  • Pozelimab

    Pozelimab is administered as an injection and is currently being studied in clinical trials for its effectiveness in treating paroxysmal nocturnal hemoglobinuria (PNH), a rare blood disorder. It works by blocking a part of the immune system called the complement system, which is overactive in PNH, leading to the destruction of red blood cells. Pozelimab is classified as a complement inhibitor, and its main therapeutic use is to reduce hemolysis, which is the breakdown of red blood cells, in patients with PNH.

  • Cemdisiran

    Cemdisiran is given as an injection and is being evaluated in clinical trials for its potential to treat paroxysmal nocturnal hemoglobinuria (PNH). It functions by targeting and reducing the production of a specific protein involved in the complement system, which is responsible for the destruction of red blood cells in PNH. Cemdisiran is categorized as a complement inhibitor, and its primary therapeutic purpose is to help prevent hemolysis, thereby reducing the need for blood transfusions in patients with PNH.

Investigated diseases

Paroxysmal Nocturnal Hemoglobinuria (PNH) – Paroxysmal nocturnal hemoglobinuria is a rare blood disorder characterized by the destruction of red blood cells. This destruction occurs due to a defect in the surface proteins of red blood cells, making them vulnerable to attack by the body's immune system. The disease often leads to episodes of dark-colored urine, especially noticeable in the morning, due to the release of hemoglobin from destroyed red blood cells. Over time, PNH can cause fatigue, shortness of breath, and an increased risk of blood clots. The progression of the disease can vary, with some individuals experiencing mild symptoms and others facing more severe complications. The condition is chronic and requires ongoing monitoring to manage its effects on the body.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-509657-31-00Protocol codeR3918-PNH-2021Estimated enrolment190 patientsSponsorRegeneron Pharmaceuticals Inc.

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