ClinicalTrials.gov record NCT05744921

A Study in Adult Patients With Paroxysmal Nocturnal Hemoglobinuria (PNH) to Evaluate How Safe Long-term Treatment With Pozelimab + Cemdisiran Combination Therapy is and How Well it Works

Record copied from ClinicalTrials.gov: Oct 10, 2026AI summaries generated: Jul 27, 2026

An Open-Label Extension Study to Evaluate the Long-Term Safety, Tolerability, and Efficacy of Pozelimab and Cemdisiran Combination Therapy in Patients With Paroxysmal Nocturnal Hemoglobinuria

StatusRecruitingThe study is currently enrolling participants. Only the study team can say whether a particular person can join.
Study typeInterventionalA study in which researchers assign participants to one or more interventions, such as a drug, procedure, device, behavioural programme or other approach, to measure their effects.
PhasePhase 3A later-stage study, usually with more participants, designed to give stronger evidence about how well a treatment works and how safe it is. It often compares the treatment with standard care or a placebo, and results may support an application for approval.
Age18 years old and older
SexAll
LocationBrazil, Canada, Colombia, Hungary, India, Italy, Japan, Jordan, Malaysia, Peru, Philippines, Poland, Romania, Singapore, South Korea, Spain, Taiwan, Thailand, Turkey, United Kingdom
AI summaryWhat this study is about, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

This open-label extension studies long-term safety, tolerability, and efficacy of pozelimab plus cemdisiran in adults with paroxysmal nocturnal hemoglobinuria (PNH). It includes people who completed a related parent study and people with a C5 genetic variation that makes them unresponsive to eculizumab or ravulizumab. Participants receive the two study drugs per protocol and are followed with regular clinic visits, blood tests, and questionnaires, with outcomes collected through planned assessments up to about week 108.

What it is studying. The study is testing the long-term safety and tolerability of the pozelimab plus cemdisiran combination and whether the combination controls hemolysis and affects transfusion needs. It will also measure blood markers (including LDH), drug concentrations, and whether participants develop anti-drug antibodies, plus patient-reported fatigue and quality-of-life measures.

What the researchers hope to learn. To evaluate long-term safety and tolerability of the pozelimab + cemdisiran combination; to assess effects on hemolysis (LDH), transfusion requirements, hemoglobin stabilization, patient-reported fatigue and quality of life; and to characterize drug concentrations, complement activity, and treatment-emergent anti-drug antibodies.

What this study is about

The study's own summary, as published on ClinicalTrials.gov. Underlined terms have a short explanation.

This study is researching an experimental treatment combination with two experimental drugs called pozelimab and cemdisiran. The study is focused on people with paroxysmal nocturnal hemoglobinuria (PNH). The aim of this study is to see how safe and effective the pozelimab + cemdisiran combination is for people with PNH in the long term. The pozelimab + cemdisiran combination may be referred to as "study drugs" in this section. This study is looking at several other research questions, including:

  • How effective is the pozelimab + cemdisiran combination?
  • What side effects may happen from taking the study drugs?
  • How much of each study drug is in the blood at different times?
  • Whether the body makes antibodies against the study drugs (which could make the drugs less effective or could lead to side effects)

Interventions being studied

Being studied in this trial does not mean the treatment or procedure is approved or available for this condition.

Drug
  • Pozelimab
  • Cemdisiran

Eligibility

The criteria exactly as listed on ClinicalTrials.gov. Only the study team can say whether they apply to you.

Inclusion criteria

  • Patients Entering from the Parent Study
  • Patients with PNH who have completed, without permanent discontinuation, study treatment in the parent study (R3918-PNH-2021[NCT05133531]), including the post-Open-label treatment period (OLTP) transition period, if applicable.
  • Willing and able to comply with clinic visits and study-related procedures, including meningococcal vaccinations required per protocol.
  • Patients Entering with C5 polymorphism
  • Patients with PNH who have a documented C5 polymorphism rendering them refractory to eculizumab or ravulizumab (eg, p.Arg885His, p.Arg885Cys), as described in the protocol
  • Diagnosis of PNH confirmed by high-sensitivity flow cytometry testing with PNH granulocytes or monocytes
  • Active disease, as defined by the presence of 1 or more PNH-related sign or symptom as described in the protocol
  • LDH level ≥2 × upper limit of normal (ULN) at the screening visit
  • Willing and able to comply with clinic visits and study-related procedures, including meningococcal vaccinations required per protocol
  • Key

Exclusion criteria

  • Patients Entering from the Parent Study
  • Significant protocol deviation(s) in the parent study based on the investigator's judgment and to the extent that these would (if continued) impact the study objectives and/or safety of the patient
  • Any new condition or worsening of an existing condition which, in the opinion of the investigator, would make the patient unsuitable for enrollment or could interfere with the patient participating in or completing the study
  • Patients Entering with C5 polymorphism
  • Prior treatment with complement inhibitors within 5 half-lives of the respective agent prior to screening, except for prior eculizumab or ravulizumab which are not exclusionary
  • Receipt of an organ transplant, history of bone marrow transplantation or other hematologic transplant
  • Not meeting meningococcal vaccination requirements and, at a minimum, documentation of quadrivalent meningococcal vaccination within 5 years prior to enrollment and serotype B vaccine within 3 years prior to enrollment as described in the protocol
  • Positive hepatitis B surface antigen or hepatitis C virus Ribonucleic acid (RNA) during screening
  • Patients with known HIV with history of opportunistic infections in the last 1 year as described in the protocol
  • Known hereditary complement deficiency
  • Documented history of active, uncontrolled, ongoing systemic autoimmune diseases
  • Documented history of liver cirrhosis or patients with liver disease with evidence of current impaired liver function or patients with elevations in Alanine aminotransferase (ALT) or Aspartate aminotransferase (AST) (unrelated to PNH or its complications) as described in the protocol
  • Note: Other protocol-defined Inclusion/ Exclusion Criteria apply

Study description and what participation involves

The registry record has no detailed description beyond the summary above.

AI summaryWhat participation may involve, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

Participants receive the study drugs pozelimab and cemdisiran given per the study protocol (the C5-polymorphism group receives an IV loading dose of pozelimab on Day 1). They will attend regular clinic visits for safety monitoring, blood tests (including LDH and measurements of drug levels, anti-drug antibodies, and complement C5), and complete fatigue and quality-of-life questionnaires. Meningococcal vaccination must be documented per protocol. Safety and other study outcomes are followed and recorded through scheduled visits (outcomes are tracked up to week 108 in the registry).

How the study is structured. An open-label, non-randomized Phase 3 extension where all participants receive pozelimab and cemdisiran in two experimental groups (those transitioning from a parent study and those with a C5 polymorphism). There is no masking or placebo. Participants attend regular clinic visits for safety assessments, blood tests, questionnaires, and drug/antibody measurements over the planned follow-up (outcomes collected through about week 108).

Questions you could ask

These questions are suggestions for a conversation with the study team or your own clinician, not advice.

  • The listed sites are in Brazil, Canada, Colombia, Hungary, India, Italy, Japan, Jordan, Malaysia, Peru, Philippines, Poland, Romania, Singapore, South Korea, Spain, Taiwan, Thailand, Turkey, United Kingdom. Is any of them reachable for me, and does the study help with travel?
  • Which of the eligibility criteria would need to be checked with tests before I could join?

More on paroxysmal nocturnal hemoglobinuria

Clinical trials44 trials listed for paroxysmal nocturnal hemoglobinuriaEvery trial the registry lists for paroxysmal nocturnal hemoglobinuria, with recruitment status, phase and sites, updated from ClinicalTrials.gov.See all trials →Research updatesWhat changed in paroxysmal nocturnal hemoglobinuria researchLatest monthly update: September 2026. Includes: Treatment access. New research summarized each month in plain language, with links to every source paper.Read the latest update →

Important dates

Study start
Mar 7, 2023
Primary completion
Oct 10, 2028 (estimated)
Study completion
Oct 10, 2028 (estimated)
Target enrollment
202 participants (estimated)
Last updated on registry
Sep 28, 2026
Data verified
Oct 10, 2026

Sponsor and research team

The lead sponsor funds and oversees the trial. A pharmaceutical or biotech company sponsor typically means the study is testing that company's drug or device; a hospital, university, or government agency usually indicates investigator-initiated or publicly funded research.

Lead sponsor
Regeneron Pharmaceuticals

Central study contact

If you're interested in participating, the central contact can answer general questions about the study — including eligibility requirements and how to find a recruiting site near you. Actual eligibility is determined by the site's medical team.

Participating sites (48)

  • A Beneficencia Portuguesa de Sao Paulo, BP MiranteRecruiting

    São Paulo, 01321-001 · Brazil

  • Toronto General HospitalRecruiting

    Toronto, Ontario, M5G 2C4 · Canada

  • Hospital Pablo Tobon UribeRecruiting

    Medellín, Antioquia, 050034 · Colombia

  • Semmelweis University/Semmelweis EgyetemRecruiting

    Budapest, 1083 · Hungary

  • Amrita Institute of Medical Sciences (AIMS) and Research Centre AimsRecruiting

    Kochi, Kerala, 682041 · India

  • K J Somaiya Super Specialty Hospital & Research CentreRecruiting

    Mumbai, Maharashtra, 400022 · India

  • Rajiv Gandhi Cancer Institute & Research Center (RGCIRC) - Rohini CampusRecruiting

    New Delhi, National Capital Territory of Delhi, 110085 · India

  • Postgraduate Institute of Medical Education & ResearchRecruiting

    Chandigarh, 160012 · India

  • Bhagwan Mahaveer Cancer Hospital and Research Centre (BMCHRC)Recruiting

    Jaipur, 302017 · India

  • Aou CareggiRecruiting

    Florence, Firenze, 50139 · Italy

Terms used on this page · explanations by MedicalUpdates.ai

study drug
A treatment that is being tested and has not been approved for this use. It may be approved for a different condition. Being studied does not mean it works or is available outside the study.
Open-label
No masking is used, so the assigned intervention is not deliberately hidden from participants or study staff.
refractory
A condition that has not responded to a treatment. 'Relapsed' means it responded and then came back; 'refractory' means it did not respond in the first place.
upper limit of normal
The highest value of a blood test that a laboratory considers normal. Criteria such as '≤ 3 × ULN' mean the result must be no more than three times that value.
screening visit
The checks done before enrolment to see whether a person qualifies, such as tests, scans or a review of medical history.
enrollment
The number of participants a study plans to include, or has included. 'Estimated' means the planned number; 'actual' means the number who joined.
Prior treatment
Treatment a person has already had for the condition. A 'line of therapy' is one course of treatment; studies often require, or limit, the number of prior lines.
5 half-lives
The time it takes for the amount of a drug in the body to fall by half. 'Five half-lives' is often used as the point at which a previous drug has essentially left the body.
Exclusion Criteria
The conditions that rule a person out even if they meet the inclusion criteria, for example other illnesses, certain medicines or pregnancy.
Key Inclusion Criteria
The conditions a person must meet to be considered for the study, for example a confirmed diagnosis, an age range or a test result.

The study record on this page is reproduced from ClinicalTrials.gov, a database of the U.S. National Library of Medicine, where it was submitted by the study sponsor. MedicalUpdates.ai does not own this content, is not affiliated with or endorsed by ClinicalTrials.gov, NIH, or the U.S. Government, and does not verify the record. Plain-language notes, the glossary and the questions above are added by this site; text in the boxes marked "AI summary" was written by an AI model and may contain errors. Registry records change over time. Check the original record for the current version and discuss eligibility or participation with a qualified healthcare professional.

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