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Long-term safety and effectiveness study of pozelimab and cemdisiran combination treatment in adults with paroxysmal nocturnal hemoglobinuria (PNH)

Verified siteInvestigationalNo placebo
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What is this trial about?

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

This study focuses on patients with Paroxysmal Nocturnal Hemoglobinuria (PNH), a rare blood disorder where the immune system attacks and destroys red blood cells, causing them to break down prematurely. The study will evaluate a combination treatment using two medications: Pozelimab and Cemdisiran. Both medications are given as solutions for injection under the skin.

The main purpose of this research is to understand how safe and effective this combination therapy is when used for a long time in patients with PNH. The study will look at how well the treatment works by monitoring various aspects of the disease, including the levels of a substance called lactate dehydrogenase (LDH) in the blood, which indicates the extent of red blood cell destruction.

During the study, participants will receive both medications through subcutaneous injections. The treatment period will last for approximately 108 weeks, during which researchers will monitor the patients' response to the treatment and any side effects that may occur. The study will also track other important measures such as the need for blood transfusions and changes in patients' quality of life.

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 treatment phase

    You will receive two medications: pozelimab and cemdisiran

    Both medications will be given as injections under the skin (subcutaneous injection)

    The treatment continues as part of a long-term safety and effectiveness study

  2. Step 2

    Regular monitoring

    Your blood will be tested regularly to measure lactate dehydrogenase (LDH) levels, which indicate how well the treatment is working

    Your hemoglobin levels will be monitored throughout the study

    Blood samples will be taken to check the levels of both medications in your system

  3. Step 3

    Safety assessments

    Regular health checks will be performed to monitor for any side effects

    You will need to receive meningococcal vaccinations as required by the study protocol

    Any unusual symptoms or health changes should be reported during clinic visits

  4. Step 4

    Quality of life evaluations

    You will complete questionnaires about your fatigue levels

    Your physical function will be assessed using specific evaluation tools

    Your overall quality of life will be monitored throughout the study

  5. Step 5

    Long-term follow-up

    The study will continue until May 2029

    Regular clinic visits will be required throughout the study period

    Your response to treatment will be monitored continuously

Who can join the trial?

8 criteria

  • Must have completed the previous study (parent study) for PNH treatment without permanently stopping the treatment
  • Must be willing and able to attend clinic visits and follow study procedures, including getting required meningococcal vaccinations (vaccines that protect against certain bacterial infections)
  • For patients with specific genetic variation: Must have a documented C5 polymorphism (a genetic change that makes certain treatments ineffective)
  • For patients with specific genetic variation: Must have PNH confirmed by special blood testing called high-sensitivity flow cytometry
  • For patients with specific genetic variation: Must have active disease with at least one PNH-related sign or symptom
  • For patients with specific genetic variation: Must have LDH levels (a blood test that measures tissue damage) at least 2 times higher than the normal upper limit during screening
  • Both male and female patients can participate
  • Must be an adult or adolescent (study includes people aged 12 years and older)

Who cannot join the trial?

15 criteria

  • History of bone marrow failure syndrome (conditions affecting blood cell production in bone marrow)
  • Active or chronic bacterial infections
  • Known or suspected active viral hepatitis (liver inflammation caused by viruses)
  • Current HIV infection
  • History of major organ transplantation
  • Any active malignancy (cancer) or history of cancer within the past 5 years
  • Severe kidney disease requiring dialysis
  • Severe liver disease
  • History of blood clotting disorders
  • Participation in another clinical trial within the past 30 days
  • Pregnant or breastfeeding women
  • Known allergic reactions to similar medications
  • Significant heart conditions or uncontrolled high blood pressure
  • Use of certain medications that could interact with the study drug
  • Mental conditions that could affect the ability to provide informed consent
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Investigated drugs

Pozelimab is a medication designed to treat patients with Paroxysmal Nocturnal Hemoglobinuria (PNH), a rare blood disorder. It works by targeting specific proteins in the immune system that are involved in the destruction of red blood cells. Cemdisiran is also used in treating Paroxysmal Nocturnal Hemoglobinuria (PNH). It works by reducing the activity of certain proteins that contribute to the breakdown of red blood cells in patients with PNH. The combination of these two medications (Pozelimab and Cemdisiran) is being studied to see how well they work together over a long period and how safe they are when used in combination to treat patients with PNH. This combination therapy approach aims to provide better control of the disease symptoms than using either medication alone.

What is already known about the treatment

  • Pozelimab

    A monoclonal antibody medication administered through subcutaneous injection that is currently being investigated in clinical trials for the treatment of Paroxysmal Nocturnal Hemoglobinuria (PNH). The drug works by targeting and inhibiting complement protein C5, which plays a key role in red blood cell destruction characteristic of PNH. This investigational therapy belongs to the class of complement inhibitors and is being studied in combination therapy to potentially provide long-term management of PNH symptoms.

  • Cemdisiran

    An investigational RNA interference therapeutic agent administered subcutaneously that is being studied for treating Paroxysmal Nocturnal Hemoglobinuria (PNH) in combination with pozelimab. The medication works by reducing the production of complement component C5 in the liver through RNA interference mechanism, helping to prevent the destruction of red blood cells. This novel drug belongs to the class of small interfering RNA therapeutics and represents a new approach to treating complement-mediated diseases.

Investigated diseases

Paroxysmal Nocturnal Hemoglobinuria (PNH) – A rare blood disorder where the body's immune system attacks and destroys its own red blood cells, leading to their premature breakdown. The condition occurs due to genetic changes in blood-forming stem cells, causing red blood cells to become sensitive to destruction by the body's complement system. The disease gets its name from the historical observation that symptoms often worsen at night, though this can occur at any time. Patients experience episodes of red blood cell destruction, which can lead to anemia and the release of hemoglobin in the urine, making it appear dark. The condition is chronic and can affect multiple body systems.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-510336-36-00Protocol codeR3918-PNH-2050Estimated enrolment202 patientsSponsorRegeneron Pharmaceuticals Inc.

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