AuthorisedTherapeutic confirmatory (Phase III)Interventional

A Single Arm Study to Evaluate the Efficacy and Safety of Pozelimab and Cemdisiran Combination Therapy in Patients with Paroxysmal Nocturnal Hemoglobinuria with Inadequate Control of Intravascular Hemolysis on Currently Available C5 Inhibitor Therapy

This research is investigating a new treatment approach for adults living with Paroxysmal Nocturnal Hemoglobinuria (PNH). PNH is a rare blood disorder that can cause red blood cells to break down too quickly. Some people with PNH find that their current treatments, called C5 inhibitors, don't fully control their condition. This study is testing a combination of two new drugs, Pozelimab and Cemdisiran, to see if they can be more effective. Researchers will measure how well the drugs reduce a specific marker in the blood called LDH, which indicates how much red blood cell damage is occurring. They will also look at whether patients feel less tired, need fewer blood transfusions, and experience any side effects. This is a Phase 3 study, meaning it's a key step to see if the treatment works and is safe for wider use.

At a glance

Status

Authorised

Phase

Therapeutic confirmatory (Phase III)

Sponsor

Regeneron Pharmaceuticals Inc.

Enrolment target

Start

21 Oct 2025

Paroxysmal nocturnal hemoglobinuria (PNH)

What is this study about?

This clinical trial is designed to investigate a new treatment for a rare blood condition called Paroxysmal Nocturnal Hemoglobinuria, or PNH. In PNH, some of your red blood cells are faulty and get destroyed too soon. This can lead to symptoms like tiredness, anaemia, and other serious problems. Currently, there are treatments available for PNH, but for some people, these treatments might not fully control the breakdown of their red blood cells. When this happens, we call it 'inadequate control of intravascular haemolysis'.

This study is testing a new combination of two medicines, Pozelimab and Cemdisiran, to see if they can work together to better manage PNH for those who aren't getting enough benefit from their current C5 inhibitor treatment. The main thing the researchers want to find out is how much this combination treatment can reduce a specific blood marker called Lactate Dehydrogenase (LDH). High levels of LDH can indicate that red blood cells are being destroyed.

The trial also aims to see if the new treatment can help improve other important aspects of living with PNH. This includes checking if patients need fewer blood transfusions, if their haemoglobin levels (which indicate iron-rich blood) stabilise, and if they feel less tired. They will also keep a close eye on any side effects, as safety is always a top priority in any new treatment investigation. This is a Phase 3 study, which means it's a crucial stage to confirm the effectiveness and safety of the combination before it could potentially become widely available.

Key takeaways

This study is for adults with PNH whose current treatment isn't fully controlling their condition.
It tests two new drugs, Pozelimab and Cemdisiran, given together.
The main aim is to reduce red blood cell damage (measured by LDH levels).
Researchers will also look at tiredness, blood transfusions, and safety.
This is a Phase 3 study, a crucial step for new treatments.
Participation involves regular clinic visits for monitoring and medication.

Who may be eligible?

This study is looking for adults aged 18 or older who have been diagnosed with Paroxysmal Nocturnal Hemoglobinuria (PNH) and whose condition isn't fully controlled by their current C5 inhibitor treatment. This means that even with their current medication, they might still be experiencing significant breakdown of their red blood cells.

Both men and women can take part in this study. The researchers will have a detailed list of other medical criteria to ensure that the study is safe and appropriate for all participants. These criteria often include things like your general health, other medical conditions you might have, and medications you are currently taking.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you 18 years old or older?
Have you been diagnosed with Paroxysmal Nocturnal Hemoglobinuria (PNH)?
Are you currently taking a C5 inhibitor medication for your PNH?
Do you feel your current PNH treatment isn't fully controlling your condition (e.g., still experiencing symptoms or red blood cell breakdown)?
Are you able to attend regular clinic appointments for treatment and check-ups?

Answer every question to see your result.

What does participation involve?

If you decide to take part in this study, you would receive the new combination treatment, Pozelimab and Cemdisiran. This involves regular visits to the clinic for assessments and to receive your medication. During these visits, the study team will take blood samples to check your LDH levels, haemoglobin, and other blood markers related to PNH and the study drugs. They will also monitor your overall health, ask about any symptoms you're experiencing, and check for any side effects.

You would complete questionnaires to assess your fatigue levels, and your need for blood transfusions will be monitored. The study will likely involve regular follow-up for up to a year (52 weeks), possibly with an option to continue treatment in an extension period. The total duration of your active participation, including all treatment and follow-up, would be made clear to you before you join.

Potential risks and benefits

Taking part in a clinical trial offers potential benefits, such as access to a new treatment before it's widely available, and close medical monitoring. For this study, if the treatment is effective, it could lead to better control of your PNH symptoms and improved quality of life. However, there are also potential risks, including side effects from the new medications, which will be carefully monitored. The new drugs might not work for everyone, or they could have unexpected effects. Full details of known and potential risks will be discussed with you by the study team. Remember, your participation is completely voluntary, and you have the right to withdraw from the study at any time, for any reason, without it affecting your usual medical care.

Locations (3)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
Poland
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Unverified
Italy
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Unverified
Spain

Common questions

What is PNH?

PNH stands for Paroxysmal Nocturnal Hemoglobinuria. It's a rare blood disorder where red blood cells break down too quickly, causing various health problems.

What are C5 inhibitors?

C5 inhibitors are a type of medicine currently used to treat PNH by helping to stop the breakdown of red blood cells.

What is LDH?

LDH (Lactate Dehydrogenase) is a substance measured in your blood. High levels can indicate that red blood cells are being damaged or destroyed.

What does 'Phase 3' mean for a clinical trial?

Phase 3 means this is a key stage of testing. It's designed to confirm if a new treatment is effective and safe compared to existing options, or if it works better for specific patient groups.

Can I stop participating in the study if I want to?

Yes, absolutely. You have the right to leave the study at any point, and it won't affect your ongoing medical care.