RecruitingPHASE1, PHASE2INTERVENTIONAL

A First-in-Human Safety and Efficacy Study of ALN-CFB, a Small Interfering RNA (siRNA) Targeting Complement Factor B, in Adult Participants With Paroxysmal Nocturnal Hemoglobinuria With Persistent Anemia on a C5 Inhibitor

This research study is investigating a new medication called ALN-CFB. It's for adults with a rare blood disorder called Paroxysmal Nocturnal Hemoglobinuria (PNH). Specifically, the study is for people who are already taking another medicine called a C5 inhibitor, but still have low red blood cell counts (anaemia). The main goals are to find out how safe ALN-CFB is, whether it causes side effects, and how well people tolerate it compared to a placebo (a dummy drug that looks the same but contains no active medicine). Researchers will also check how the drug works in the body and if it affects certain blood protein levels.

At a glance

Status

Recruiting

Phase

PHASE1, PHASE2

Sponsor

Regeneron Pharmaceuticals

Enrolment target

Start

11 Feb 2026

Estimated completion

15 Jul 2031

Paroxysmal Nocturnal Hemoglobinuria (PNH)Persistent Anemia

What is this study about?

This research study is looking into a new experimental medicine called ALN-CFB. It's designed for people who have a rare blood condition called Paroxysmal Nocturnal Hemoglobinuria, often shortened to PNH. PNH can cause red blood cells to break down, leading to various symptoms, including anaemia, which means having low numbers of red blood cells.

Many people with PNH are already treated with a type of medicine called a C5 inhibitor. However, for some, even with this treatment, their anaemia can continue. This study is specifically for these individuals – those with PNH who are on a C5 inhibitor but still suffer from ongoing anaemia.

The main purpose of this study is to carefully check how safe ALN-CFB is and how well people tolerate it. To do this, some participants will receive ALN-CFB, while others will receive a placebo. A placebo looks exactly like the study medicine but doesn't contain any active drug. Researchers will also be monitoring for any side effects, how much of the drug stays in the blood, and if it changes levels of a protein called Complement Factor B.

Key takeaways

This study explores a new drug called ALN-CFB for PNH patients with unresolved anaemia.
It's for adults already on a C5 inhibitor but still experiencing low red blood cell counts.
The main goals are to check the drug's safety, side effects, and how well it's tolerated.
Some participants will receive the active drug, others a placebo (dummy drug).
Close medical monitoring will be part of the study participation.

Who may be eligible?

To join this study, you must be an adult aged 18 or over. You need to have been diagnosed with PNH, confirmed by specific blood tests. It's also important that you've been consistently taking your current PNH medication (a C5 inhibitor like eculizumab, ravulizumab, or crovalimab) for at least 24 weeks before the study starts.

Your blood tests will need to show that you still have anaemia, meaning your haemoglobin level is 10.5 g/dL or lower, and you have a certain level of developing red blood cells (reticulocytes).

You wouldn't be able to join this study if you've had a bone marrow or organ transplant, or if you've had certain serious infections, such as meningococcal infection. Active infections or recent serious infections needing treatment would also prevent you from joining. Additionally, if you have other severe medical conditions not related to your PNH, or if tests show your bone marrow isn't working properly, you might not be suitable.

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?
Do you have a diagnosis of PNH confirmed by medical tests?
Have you been taking your current PNH C5 inhibitor medication regularly for at least 6 months?
Do you still have low red blood cell counts (anaemia) despite your current PNH treatment?
Have you *not* had a bone marrow or organ transplant?
Do you *not* have any active, serious infections or recent infections needing ongoing treatment?

Answer every question to see your result.

What does participation involve?

If you join this study, you'll either receive the experimental drug, ALN-CFB, or a placebo. Neither you nor your doctor will know which one you're receiving. You'll have regular visits to the study clinic for check-ups, which will include blood tests, physical exams, and answering questions about how you’re feeling. These visits are important for doctors to monitor your health, check for side effects, and see how the study drug is working. The total time you'd be involved in the study isn't specified here, but clinical studies usually involve a series of visits over several months.

Potential risks and benefits

Taking part in any clinical study has potential benefits and risks. You might benefit from the new medication if it works, and you'll be closely monitored by medical professionals. However, there's a chance you could experience side effects, just like with any medication, and there's no guarantee the treatment will improve your condition. Researchers don't yet know all the effects of ALN-CFB. You are free to withdraw from the study at any time, for any reason, without it affecting your usual medical care.

Locations (7)

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

Toronto General Hospital
Verified postcode
Toronto, Canada· Recruiting
St. Vincent Hospital - The Catholic University of Korea
Verified postcode
Suwon, South Korea· Recruiting
Seoul National University Hospital
Verified postcode
Seoul, South Korea· Recruiting
The Catholic University of Korea, Seoul St. Mary's Hospital
Verified postcode
Seoul, South Korea· Recruiting
Severance Hospital
Verified postcode
Seoul, South Korea· Recruiting
Samsung Medical Center
Verified postcode
Seoul, South Korea· Recruiting
St. James's University Hospital
Verified postcode
Leeds, United Kingdom· Recruiting

Common questions

What is PNH?

PNH is a rare blood disorder where red blood cells break down too early, leading to symptoms like tiredness (from anaemia) and blood clots.

What is a C5 inhibitor?

A C5 inhibitor is a type of medicine currently used to treat PNH by stopping some of the red blood cell breakdown.

What is a 'placebo' in this study?

A placebo is a 'dummy' treatment that looks like the real study drug but contains no active medicine. It helps researchers fairly compare the new drug's effects.

Will I know if I'm getting the study drug or the placebo?

No, this study is 'blinded,' meaning neither you nor your doctors will know if you're receiving ALN-CFB or the placebo until after the study is complete, or in an emergency.

What does 'first-in-human' mean?

It means this is one of the first times this new drug is being given to people, after extensive testing in laboratories, to carefully check its safety and how it works.

How to find out more

Clinical Trials Administrator

clinicaltrials@regeneron.com 844-734-6643 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.