Paroxysmal Nocturnal HemoglobinuriaPhase 2NCT04888507
Pozelimab and Cemdisiran Combination Therapy in Adult Participants With Paroxysmal Nocturnal Hemoglobinuria Who Switch From Eculizumab Therapy
A Phase 2 study testing Pozelimab and Cemdisiran in people with Paroxysmal Nocturnal Hemoglobinuria, run by Regeneron Pharmaceuticals at 1 site in United Kingdom.
Trial summary
The primary objective of the study is to evaluate the safety and tolerability of pozelimab and cemdisiran combination therapy in participants with PNH who switch from eculizumab therapy The secondary objectives of the study are: To evaluate the effect of the combination treatment on the following parameters of… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Paroxysmal Nocturnal Hemoglobinuria
- What is being tested?
- Pozelimab and Cemdisiran
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 6 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 8 Jul 2021to 4 May 2023
- Phase
- Phase 2
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Diagnosis of paroxysmal nocturnal hemoglobinuria confirmed by a history of high-sensitivity flow cytometry from prior testing
- Treated with stable (ie, no change in dose or frequency) eculizumab therapy at the labeled dosing regimen or a higher dose and/or more frequently administered than labeled for at least 12 weeks prior to screening visit
Who cannot join
- History of bone marrow transplantation or receipt of an organ transplant
- Body weight <40 kg at screening
- Current plans for modification of the following background concomitant medications, as applicable, during screening and treatment period: erythropoietin, immunosuppressive drugs, corticosteroids, anti-thrombotic agents, anticoagulants, iron supplements, and folic acid as described in the protocol
- Any use of complement inhibitor therapy other than eculizumab in the 12 weeks prior to the screening visit or planned use during the study
- Known hypocellular bone marrow based on a history of reduced age-adjusted bone marrow cellularity and/or bone marrow cellularity ≤25%
- No documented meningococcal vaccination within 5 years prior to screening visit unless it is documented that vaccination has been administered during the screening period and prior to initiation of study treatment
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- Unable to take antibiotics for meningococcal prophylaxis, if required by local standard of care
- Any active, ongoing infection or a recent infection requiring ongoing systemic treatment with antibiotics, antivirals, or antifungals within 2 weeks of screening or during the screening period
- Documented positive polymerase chain reaction (PCR) or equivalent test based on regional recommendations for COVID-19 or suspected SARS-CoV-2 infection as described in the protocol
- Documented history of active, uncontrolled, ongoing systemic autoimmune diseases
- Recent, unstable medical conditions, excluding PNH and PNH-related complications, within the past 3 months prior to screening visit as described in the protocol
- Anticipated need for major surgery during the study
- NOTE: Other protocol-defined Inclusion/ Exclusion Criteria apply.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: A Single Arm, Open-Label Study to Assess the Safety, Efficacy, and Pharmacodynamic Effects of Pozelimab and Cemdisiran Combination Therapy in Patients With Paroxysmal Nocturnal Hemoglobinuria Who Switch From Eculizumab Therapy
The primary objective of the study is to evaluate the safety and tolerability of pozelimab and cemdisiran combination therapy in participants with PNH who switch from eculizumab therapy
The secondary objectives of the study are:
- To evaluate the effect of the combination treatment on the following parameters of intravascular hemolysis: lactate dehydrogenase (LDH) control, breakthrough hemolysis, and inhibition of CH50
- To evaluate the effect of the combination treatment on the stability of LDH during the transition period from eculizumab monotherapy to combination with pozelimab and cemdisiran
- To evaluate the effect of the combination treatment on red blood cell (RBC) transfusion requirements
- To evaluate the effect of the combination treatment on hemoglobin levels
- To evaluate the effect of the combination treatment on clinical outcome assessments (COAs) measuring fatigue and health related quality of life (HRQoL)
- To assess the concentrations of total pozelimab and eculizumab in serum; and total cemdisiran and C5 protein in plasma
- To assess the immunogenicity of pozelimab and cemdisiran
- To assess safety after dose intensification
- To evaluate the long-term safety and efficacy of the combination treatment in an optional open-label extension period (OLEP)
- Conditions
- Paroxysmal Nocturnal Hemoglobinuria
- Being tested
- Pozelimab, Cemdisiran
- Keywords
- PNH
- Medical subject headings
- Hemoglobinuria, Paroxysmal
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
PozelimabDrug
Also called REGN3918
Intravenous (IV) loading dose (once) followed after 30 minutes by sub-cutaneous (SC) administration
CemdisiranDrug
Also called ALN-CC5
SC administration
| Study group | Role | What they receive |
|---|---|---|
| Pozelimab+Cemdisiran | Experimental | Not described Receives: Drug: Pozelimab; Drug: Cemdisiran |
What is being measured
The primary outcome is the main question the study is designed to answer.
OLTP: Number of Participants With Treatment-emergent Adverse Events (TEAEs)
Measured: Up to Day 225
Secondary outcomes (57)
OLTP: Percent Change in Lactate Dehydrogenase (LDH) From Pre-treatment to End-of-treatment Period
Measured: Screening (Day 1) through Day 225
OLTP: Percent Change in LDH From Pre-treatment Through Day 29
Measured: Screening (Day 1) through Day 29
OLTP: Percentage of Participants Who Were Transfusion-free From Baseline Through Week 32
Measured: Baseline through Week 32
OLTP: Percentage of Participants Who Were Transfusion-free From Week 4 Through Week 32
Measured: Week 4 through Week 32
OLTP: Rate of Red Blood Cell (RBC) Transfusions From Baseline Through Week 32
The rate of units of transfusion for a participant was calculated based on the duration of treatment exposure of the participant.
Measured: Baseline through Week 32
OLTP: Rate of RBC Transfusions From Week 4 Through Week 32
The rate of units of transfusion for a participant was calculated based on the duration of treatment exposure of the participant.
Measured: Week 4 through Week 32
OLTP: Number of RBC Units Transfused From Baseline Through Week 32
Measured: Baseline through Week 32
OLTP: Number of RBC Units Transfused From Week 4 Through Week 32
Measured: Week 4 through Week 32
OLTP: Percentage of Participants With Breakthrough Hemolysis From Baseline Through Week 32
Breakthrough hemolysis was defined as having an LDH ≥ 2 x upper limit of normal (ULN) and having signs or symptoms.
Measured: Baseline through Week 32
OLTP: Percentage of Participants With Breakthrough Hemolysis From Week 4 Through Week 32
Breakthrough hemolysis was defined as having an LDH ≥ 2 x ULN and having signs or symptoms.
Measured: Week 4 through Week 32
OLTP: Percentage of Participants Who Maintained Adequate Control of Hemolysis From Day 1 Through Week 32
Adequate control was defined as LDH ≤ 1.5 x ULN from Day 1 through Week 32.
Measured: Day 1 through Week 32
OLTP: Percentage of Participants Who Maintained Adequate Control of Hemolysis From Week 8 Through Week 32
Adequate control was defined as LDH ≤ 1.5 x ULN from Week 8 through Week 32.
Measured: Week 8 through Week 32
OLTP: Number of Participants With Adequate Control of Hemolysis at Each Visit
Adequate control at a visit was defined as having LDH ≤1.5 x ULN at that visit.
Measured: Days 1, 8, 15, 29, 43, 57, 71, 85, 113, 141, 169, 197, 225
OLTP: Number of Participants With Normalization of Their LDH at Each Visit
Normalization was defined as LDH ≤ 1.0 x ULN at that visit.
Measured: Days 1, 8, 15, 29, 43, 57, 71, 85, 113, 141, 169, 197, 225
OLTP: Average LDH From Baseline Through Week 32
The trapezoidal rule was used to calculate area under the curve (AUC). Individual mean LDH is defined as AUC divided by (last assessment date of LDH - first assessment date of LDH) of specific period.
Measured: Baseline through Week 32
OLTP: Average LDH From Week 8 Through Week 32
The trapezoidal rule was used to calculate AUC. Individual mean LDH is defined as AUC divided by (last assessment date of LDH - first assessment date of LDH) of specific period.
Measured: Week 8 through Week 32
OLTP: Percentage of Participants With Hemoglobin Stabilization From Baseline Through Week 32
Hemoglobin stabilization was defined as not receiving an RBC transfusion and having no decrease in hemoglobin level of ≥ 2 grams per deciliter (g/dL).
Measured: Baseline through Week 32
OLTP: Percentage of Participants With Hemoglobin Stabilization From Week 4 Through Week 32
Hemoglobin stabilization was defined as not receiving an RBC transfusion and having no decrease in hemoglobin level of ≥ 2 g/dL.
Measured: Week 4 through Week 32
OLTP: Change From Baseline in Hemoglobin Levels
Measured: Baseline, Week 32
OLTP: Change From Baseline in Fatigue as Measured by Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) Score
The FACIT-Fatigue is a 13-item, self-reported measure assessing an individual's level of fatigue during their usual daily activities over the past week. This questionnaire is part of the FACIT measurement system, a compilation of questions measuring health-related quality of life (QoL) in participants with cancer and other chronic illnesses. The FACIT-fatigue assesses the level of fatigue using a Likert scale ranging from 0 (not at all) to 4 (very much). Total scores range from 0 to 52, with higher scores indicating a higher quality of life.
Measured: Baseline, Week 32
OLTP: Change From Baseline in Health Related Quality of Life (HRQoL) as Measured by the Global Health Status Subscale of the European Organization for Research and Treatment of Cancer (EORTC)- Quality of Life Cancer Patients Questionnaire (QLQ) - 30 Scale
EORTC-QLQ-C30 is a 30-item self-reported questionnaire composed of both multi-item and single scales, including a global health status/quality of life (GHS/QoL) scale. The GHS subscale scores ranged from 0 to 100 with higher scores indicating better quality of life.
Measured: Baseline, Week 32
OLTP: Change From Baseline in Physical Function (PF) Scores on the EORTC QLQ-C30
EORTC-QLQ-C30 is a 30-item participant self-report questionnaire composed of both multi-item and single scales, including a PF scale. PF subscale scores ranged from 0 to 100 with higher scores indicating better quality of life.
Measured: Baseline, Week 32
OLTP: Change From Baseline in Total Complement Hemolytic Activity Assay (CH50)
This assay assessed the activity of the classical pathway of complement to measure C5 activity.
Measured: Baseline through Week 32
OLTP and OLEP: Concentration of Total Pozelimab in Serum
Measured: Pre-dose Days 28, 56, 84, 112, 140, 168, 196, 224, 392, 588; Post-dose Day 28
OLTP: Concentration of Total Eculizumab in Serum
Measured: Pre-dose Days 0, 14, 28, 56, 84, 112, 140, 168, 196, 224
OLTP and OLEP: Concentration of Total Cemdisiran in Plasma
Measured: Pre-dose and Post-dose Days 0, 84, 196, 224, 588
OLTP and OLEP: Concentration of Total C5 in Plasma
Measured: Pre-dose Days 0, 7, 14, 28, 56, 84, 112, 140, 168, 196, 224, 392, 588
OLTP: Number of Participants With Pozelimab Anti-drug Antibodies (ADA)
Measured: Baseline through Week 32
OLTP: Number of Participants With Cemdisiran ADA
Measured: Baseline through Week 32
OLTP: Number of Participants Who Received Dose Intensification With TEAEs
Measured: Baseline through Week 32
OLEP: Number of Participants With TEAEs
Measured: Day 1 through Week 52 of the OLEP
OLEP: Percent Change in LDH From Day 1 Through Week 24 of the OLEP
Measured: Day 1 through Week 24 of the OLEP
OLEP: Percent Change in LDH From Day 1 Through Week 52 of the OLEP
Measured: Day 1 through Week 52 of the OLEP
OLEP: Percentage of Participants Who Were Transfusion-free From Day 1 Through Week 24 of the OLEP
Measured: Day 1 through Week 24 of the OLEP
OLEP: Percentage of Participants Who Were Transfusion-free From Day 1 Through Week 52 of the OLEP
Measured: Day 1 through Week 52 of the OLEP
OLEP: Rate of RBC Transfusions From Day 1 Through Week 24 of the OLEP
The rate of units of transfusion for a participants was calculated based on the duration of treatment exposure of the participant.
Measured: Day 1 through Week 24 of the OLEP
OLEP: Rate of RBC Transfusions From Day 1 Through Week 52 of the OLEP
The rate of units of transfusion for a participants was calculated based on the duration of treatment exposure of the participant.
Measured: Day 1 through Week 52 of the OLEP
OLEP: Number of RBC Units Transfused From Day 1 Through Week 24 of the OLEP
Measured: Day 1 through Week 24 of the OLEP
OLEP: Number of RBC Units Transfused From Day 1 Through Week 52 of the OLEP
Measured: Day 1 through Week 52 of the OLEP
OLEP: Percentage of Participants With Breakthrough Hemolysis From Day 1 Through Week 24 of the OLEP
Breakthrough hemolysis was defined as having an LDH ≥ 2 x ULN and having signs or symptoms.
Measured: Day 1 through Week 24 of the OLEP
OLEP: Percentage of Participants With Breakthrough Hemolysis From Day 1 Through Week 52 of the OLEP
Breakthrough hemolysis was defined as having an LDH ≥ 2 x ULN and having signs or symptoms.
Measured: Day 1 through Week 52 of the OLEP
OLEP: Percentage of Participants Who Maintained Adequate Control of Hemolysis From Day 1 Through Week 24 of the OLEP
Adequate control was defined as LDH ≤ 1.5 x ULN.
Measured: Day 1 through Week 24 of the OLEP
OLEP: Percentage of Participants Who Maintained Adequate Control of Hemolysis From Day 1 Through Week 52 of the OLEP
Adequate control was defined as LDH ≤ 1.5 x ULN.
Measured: Day 1 through Week 52 of the OLEP
OLEP: Number of Participants Who Maintained Adequate Control of Hemolysis at Each Visit in OLEP
Adequate control was defined as LDH ≤ 1.5 x ULN at that visit.
Measured: Baseline, Days 57, 113, 169, 225, 281, 365 of the OLEP
OLEP: Number of Participants With Normalization of Their LDH at Each Visit in OLEP
Normalization was defined as LDH ≤ 1.0 x ULN at that visit.
Measured: Baseline, Days 57, 113, 169, 225, 281, 365 of the OLEP
OLEP: Average LDH From Day 1 Through Week 24 of the OLEP
The trapezoidal rule was used to calculate AUC. Individual mean LDH is defined as AUC divided by (last assessment date of LDH - first assessment date of LDH) of specific period.
Measured: Day 1 through Week 24 of the OLEP
OLEP: Average LDH From Day 1 Through Week 52 of the OLEP
The trapezoidal rule was used to calculate AUC. Individual mean LDH is defined as AUC divided by (last assessment date of LDH - first assessment date of LDH) of specific period.
Measured: Day 1 through Week 52 of the OLEP
OLEP: Percentage of Participants With Hemoglobin Stabilization From Day 1 Through Week 24 of the OLEP
Hemoglobin stabilization was defined as not receiving an RBC transfusion and having no decrease in hemoglobin level of ≥ 2 g/dL.
Measured: Day 1 through Week 24 of the OLEP
OLEP: Percentage of Participants With Hemoglobin Stabilization From Day 1 Through Week 52 of the OLEP
Hemoglobin stabilization was defined as not receiving an RBC transfusion and having no decrease in hemoglobin level of ≥ 2 g/dL.
Measured: Day 1 through Week 52 of the OLEP
OLEP: Change From Baseline in Hemoglobin Levels
Measured: Day 1 and Week 24 of the OLEP
OLEP: Change From Baseline in Hemoglobin Levels
Measured: Day 1 and Week 52 of the OLEP
OLEP: Change From Baseline in FACIT-Fatigue Score
The FACIT-Fatigue is a 13-item, self-reported measure assessing an individual's level of fatigue during their usual daily activities over the past week. This questionnaire is part of the FACIT measurement system, a compilation of questions measuring health-related quality of life (QoL) in patients with cancer and other chronic illnesses. The FACIT-fatigue assesses the level of fatigue using a Likert scale ranging from 0 (not at all) to 4 (very much). Total scores range from 0 to 52, with higher scores indicating a higher quality of life.
Measured: Day 1 and Week 52 of the OLEP
OLEP: Change From Baseline in HRQoL as Measured by the Global Health Status Subscale of the EORTC-QLQ-30 Scale
EORTC-QLQ-C30 is a 30-item self-reported questionnaire composed of both multi-item and single scales, including a global health status/quality of life (GHS/QoL) scale. GHS subscale scores ranged from 0 to 100 with higher scores indicating better quality of life.
Measured: Day 1 and Week 52 of the OLEP
OLEP: Change From Baseline in PF Scores on the EORTC QLQ-C30
EORTC-QLQ-C30 is a 30-item participant self-report questionnaire composed of both multi-item and single scales, including a PF scale. PF subscale scores ranged from 0 to 100 with higher scores indicating better quality of life.
Measured: Day 1 and Week 52 of the OLEP
OLEP: Change From Baseline in CH50
This assay assessed the activity of the classical pathway of complement to measure C5 activity.
Measured: Baseline, Week 16, Week 32, Week 52 of the OLEP
OLEP: Number of Participants With Pozelimab ADA
Measured: Day 1 through Week 52 of the OLEP
OLEP: Number of Participants With Cemdisiran ADA
Measured: Day 1 through Week 52 of the OLEP
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 May 2021
- Study start8 Jul 2021
- Primary completion5 May 2022
- Study completion4 May 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for Paroxysmal Nocturnal HemoglobinuriaStudies of the same condition, open and under way.
- More trials run by Regeneron PharmaceuticalsThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 6 participants (actual)
Sponsor and investigators
- Lead sponsor
- Regeneron Pharmaceuticals
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Clinical Trial Management, Study director, Regeneron Pharmaceuticals
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04888507
- Sponsor's protocol ID
- R3918-PNH-20105
- Other IDs
- 2020-005006-25
- Status last verified
- Aug 2025
- First submitted
- 23 Apr 2021
- Last updated
- 29 Aug 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing
Study at a glance
From the registry record, last updated by the sponsor on 29 Aug 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Single Arm, Open-Label Study to Assess the Safety, Efficacy, and Pharmacodynamic Effects of Pozelimab and Cemdisiran Combination Therapy in Patients With Paroxysmal Nocturnal Hemoglobinuria Who Switch From Eculizumab Therapy
- ClinicalTrials.gov ID
- NCT04888507
- Acronym / sponsor ID
- R3918-PNH-20105
- Conditions
- Paroxysmal Nocturnal Hemoglobinuria
- Keywords
- PNH
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 6 participants (actual)
- Lead sponsor
- Regeneron PharmaceuticalsIndustry (pharma, biotech, devices)
- Study start
- 8 Jul 2021 (actual)
- Primary completion
- 5 May 2022 (actual)
- Study completion
- 4 May 2023 (actual)
- First posted
- 17 May 2021 (actual)
- Results
- Posted 25 Jun 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The primary objective of the study is to evaluate the safety and tolerability of pozelimab and cemdisiran combination therapy in participants with PNH who switch from eculizumab therapy
The secondary objectives of the study are:
- To evaluate the effect of the combination treatment on the following parameters of intravascular hemolysis: lactate dehydrogenase (LDH) control, breakthrough hemolysis, and inhibition of CH50
- To evaluate the effect of the combination treatment on the stability of LDH during the transition period from eculizumab monotherapy to combination with pozelimab and cemdisiran
- To evaluate the effect of the combination treatment on red blood cell (RBC) transfusion requirements
- To evaluate the effect of the combination treatment on hemoglobin levels
- To evaluate the effect of the combination treatment on clinical outcome assessments (COAs) measuring fatigue and health related quality of life (HRQoL)
- To assess the concentrations of total pozelimab and eculizumab in serum; and total cemdisiran and C5 protein in plasma
- To assess the immunogenicity of pozelimab and cemdisiran
- To assess safety after dose intensification
- To evaluate the long-term safety and efficacy of the combination treatment in an optional open-label extension period (OLEP)
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Pozelimab+Cemdisiran | Experimental | Drug: Pozelimab, Drug: Cemdisiran |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (2 listed)
- Diagnosis of paroxysmal nocturnal hemoglobinuria confirmed by a history of high-sensitivity flow cytometry from prior testing
- Treated with stable (ie, no change in dose or frequency) eculizumab therapy at the labeled dosing regimen or a higher dose and/or more frequently administered than labeled for at least 12 weeks prior to screening visit
Key exclusion criteria (13 listed)
- History of bone marrow transplantation or receipt of an organ transplant
- Body weight <40 kg at screening
- Current plans for modification of the following background concomitant medications, as applicable, during screening and treatment period: erythropoietin, immunosuppressive drugs, corticosteroids, anti-thrombotic agents, anticoagulants, iron supplements, and folic acid as described in the protocol
- Any use of complement inhibitor therapy other than eculizumab in the 12 weeks prior to the screening visit or planned use during the study
- Known hypocellular bone marrow based on a history of reduced age-adjusted bone marrow cellularity and/or bone marrow cellularity ≤25%
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| PozelimabAlso: REGN3918Intravenous (IV) loading dose (once) followed after 30 minutes by sub-cutaneous (SC) administration | Drug | Pozelimab+Cemdisiran |
| CemdisiranAlso: ALN-CC5SC administration | Drug | Pozelimab+Cemdisiran |
Primary outcome
OLTP: Number of Participants With Treatment-emergent Adverse Events (TEAEs)
Time frame: Up to Day 225
57 secondary outcomes
OLTP: Percent Change in Lactate Dehydrogenase (LDH) From Pre-treatment to End-of-treatment Period
Time frame: Screening (Day 1) through Day 225
OLTP: Percent Change in LDH From Pre-treatment Through Day 29
Time frame: Screening (Day 1) through Day 29
OLTP: Percentage of Participants Who Were Transfusion-free From Baseline Through Week 32
Time frame: Baseline through Week 32
OLTP: Percentage of Participants Who Were Transfusion-free From Week 4 Through Week 32
Time frame: Week 4 through Week 32
OLTP: Rate of Red Blood Cell (RBC) Transfusions From Baseline Through Week 32
Time frame: Baseline through Week 32
OLTP: Rate of RBC Transfusions From Week 4 Through Week 32
Time frame: Week 4 through Week 32
OLTP: Number of RBC Units Transfused From Baseline Through Week 32
Time frame: Baseline through Week 32
OLTP: Number of RBC Units Transfused From Week 4 Through Week 32
Time frame: Week 4 through Week 32
OLTP: Percentage of Participants With Breakthrough Hemolysis From Baseline Through Week 32
Time frame: Baseline through Week 32
OLTP: Percentage of Participants With Breakthrough Hemolysis From Week 4 Through Week 32
Time frame: Week 4 through Week 32
OLTP: Percentage of Participants Who Maintained Adequate Control of Hemolysis From Day 1 Through Week 32
Time frame: Day 1 through Week 32
OLTP: Percentage of Participants Who Maintained Adequate Control of Hemolysis From Week 8 Through Week 32
Time frame: Week 8 through Week 32
OLTP: Number of Participants With Adequate Control of Hemolysis at Each Visit
Time frame: Days 1, 8, 15, 29, 43, 57, 71, 85, 113, 141, 169, 197, 225
OLTP: Number of Participants With Normalization of Their LDH at Each Visit
Time frame: Days 1, 8, 15, 29, 43, 57, 71, 85, 113, 141, 169, 197, 225
OLTP: Average LDH From Baseline Through Week 32
Time frame: Baseline through Week 32
OLTP: Average LDH From Week 8 Through Week 32
Time frame: Week 8 through Week 32
OLTP: Percentage of Participants With Hemoglobin Stabilization From Baseline Through Week 32
Time frame: Baseline through Week 32
OLTP: Percentage of Participants With Hemoglobin Stabilization From Week 4 Through Week 32
Time frame: Week 4 through Week 32
OLTP: Change From Baseline in Hemoglobin Levels
Time frame: Baseline, Week 32
OLTP: Change From Baseline in Fatigue as Measured by Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) Score
Time frame: Baseline, Week 32
OLTP: Change From Baseline in Health Related Quality of Life (HRQoL) as Measured by the Global Health Status Subscale of the European Organization for Research and Treatment of Cancer (EORTC)- Quality of Life Cancer Patients Questionnaire (QLQ) - 30 Scale
Time frame: Baseline, Week 32
OLTP: Change From Baseline in Physical Function (PF) Scores on the EORTC QLQ-C30
Time frame: Baseline, Week 32
OLTP: Change From Baseline in Total Complement Hemolytic Activity Assay (CH50)
Time frame: Baseline through Week 32
OLTP and OLEP: Concentration of Total Pozelimab in Serum
Time frame: Pre-dose Days 28, 56, 84, 112, 140, 168, 196, 224, 392, 588; Post-dose Day 28
OLTP: Concentration of Total Eculizumab in Serum
Time frame: Pre-dose Days 0, 14, 28, 56, 84, 112, 140, 168, 196, 224
OLTP and OLEP: Concentration of Total Cemdisiran in Plasma
Time frame: Pre-dose and Post-dose Days 0, 84, 196, 224, 588
OLTP and OLEP: Concentration of Total C5 in Plasma
Time frame: Pre-dose Days 0, 7, 14, 28, 56, 84, 112, 140, 168, 196, 224, 392, 588
OLTP: Number of Participants With Pozelimab Anti-drug Antibodies (ADA)
Time frame: Baseline through Week 32
OLTP: Number of Participants With Cemdisiran ADA
Time frame: Baseline through Week 32
OLTP: Number of Participants Who Received Dose Intensification With TEAEs
Time frame: Baseline through Week 32
OLEP: Number of Participants With TEAEs
Time frame: Day 1 through Week 52 of the OLEP
OLEP: Percent Change in LDH From Day 1 Through Week 24 of the OLEP
Time frame: Day 1 through Week 24 of the OLEP
OLEP: Percent Change in LDH From Day 1 Through Week 52 of the OLEP
Time frame: Day 1 through Week 52 of the OLEP
OLEP: Percentage of Participants Who Were Transfusion-free From Day 1 Through Week 24 of the OLEP
Time frame: Day 1 through Week 24 of the OLEP
OLEP: Percentage of Participants Who Were Transfusion-free From Day 1 Through Week 52 of the OLEP
Time frame: Day 1 through Week 52 of the OLEP
OLEP: Rate of RBC Transfusions From Day 1 Through Week 24 of the OLEP
Time frame: Day 1 through Week 24 of the OLEP
OLEP: Rate of RBC Transfusions From Day 1 Through Week 52 of the OLEP
Time frame: Day 1 through Week 52 of the OLEP
OLEP: Number of RBC Units Transfused From Day 1 Through Week 24 of the OLEP
Time frame: Day 1 through Week 24 of the OLEP
OLEP: Number of RBC Units Transfused From Day 1 Through Week 52 of the OLEP
Time frame: Day 1 through Week 52 of the OLEP
OLEP: Percentage of Participants With Breakthrough Hemolysis From Day 1 Through Week 24 of the OLEP
Time frame: Day 1 through Week 24 of the OLEP
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Aug 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- A Plain Language Summary is available on TrialSummaries.comLink provided by the sponsor.
- Individual participant dataSharing planned: Yes. All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing
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Severe Aplastic Anemia, MDS (Myelodysplastic Syndrome)
RecruitingPhase 3
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
Paroxysmal Nocturnal Hemoglobinuria
Not yet recruitingPhase 3
A Study of Efficacy and Safety of FXS6837 in Anti-C5 Treated PNH Patients.
Paroxysmal Nocturnal Hemoglobinuria
RecruitingPhase 2
Haplo-identical Transplantation for Severe Aplastic Anemia, Hypo-plastic MDS and PNH Using Peripheral Blood Stem Cells and Post-transplant Cyclophosphamide for GVHD Prophylaxis
Severe Aplastic Anemia (SAA), Hypo-Plastic Myelodysplastic Syndrome (MDS)
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Clinical Trial Management study director
Regeneron Pharmaceuticals
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Pozelimab and Cemdisiran in people with Paroxysmal Nocturnal Hemoglobinuria, run by Regeneron Pharmaceuticals at 1 site in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 13 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 29 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 25 Jun 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
OLTP: Number of Participants With Treatment-emergent Adverse Events (TEAEs) (time frame: Up to Day 225). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 Aug 2025.