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Severe Aplastic Anemia (SAA)Phase 1NCT04409080

REGN7257 in Adult Patients With Severe Aplastic Anemia That Is Refractory to or Relapsed on Immunosuppressive Therapy

A Phase 1 study testing REGN7257 in people with Severe Aplastic Anemia (SAA), run by Regeneron Pharmaceuticals at 10 sites in 4 countries.

Terminated

Stopped early. The study ended before it was planned to and will not resume.

Official record
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Trial summary

This study is researching an experimental drug called REGN7257 (called "study drug"). The study is focused on patients who have severe aplastic anemia (SAA), a disease of the bone marrow resulting in an impairment of the production of blood cells. Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Severe Aplastic Anemia (SAA)
What is being tested?
REGN7257
Type of treatment
Injection or infusion
Could I receive a placebo?
No, everyone receives an active treatment
How many people
17 participants
Where
10 sitesin 4 countries
Study dates
13 Jan 2021to 17 Oct 2024
Phase
Phase 1
Are there results?
None posted in the registry

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

  • Part A: SAA that is IST-refractory or IST-relapsed, as defined in the protocol
  • Part B: SAA that is IST-relapsed, as defined in the protocol
  • Hematopoietic stem cell transplantation (HSCT) is not available or suitable as a treatment option or has been refused by the patient
  • Adequate hepatic and renal function as defined in the protocol

Who cannot join

  • Diagnosis of Fanconi anemia or other congenital bone marrow failure syndrome as defined in the protocol
  • Evidence of myelodysplastic syndrome as defined in the protocol
  • Paroxysmal nocturnal hemoglobinuria (PNH) with evidence of clinically significant hemolysis (eg, treatment indicated) or history of PNH-associated thrombosis
  • Treatment with a T cell-depleting agent (eg, ATG or alemtuzumab) within 6 months prior to dosing
  • Treatment with a calcineurin inhibitor (eg, cyclosporine) within 4 weeks prior to dosing for patients enrolled in Part A
  • Treatment with eltrombopag or investigational thrombopoietin receptor agonist, Granulocyte Colony-Stimulating Factor (G-CSF), or an androgen (eg, danazol), within 2 weeks prior to dosing
Show all 10Show fewer
  • HIV, hepatitis B or hepatitis C positive by serological testing at the screening visit as defined in the protocol
  • Active tuberculosis, latent tuberculosis infection (LTBI) or history incompletely-treated tuberculosis or LTBI
  • Active infection as defined in the protocol
  • Note: Other protocol-defined inclusion/ exclusion criteria apply

Trial locations and contacts

10 sites in 4 countries.

10 sites in 4 countries

South Korea5 sites

  • Gachon University Gil Hospital

    Incheon, Gyeonggi-do, 21565

  • Seoul National University Hospital

    Seoul, Seoul Capital Area, 03080

  • Samsung Medical Center

    Seoul, Seoul Capital Area, 06351

  • The Catholic University of Korea, Seoul St. Marys Hospital

    Seoul, Seoul Capital Area, 06591

  • Ewha Womans University Medical Centre

    Seoul, Seoul Capital Area, 07985

Other trials in South Korea

United States2 sites

  • Cleveland Clinic Foundation

    Cleveland, Ohio, 44195

  • The University of Texas MD Anderson Cancer Center

    Houston, Texas, 77030

Other trials in United States

United Kingdom2 sites

  • St James's University Hospital

    Leeds, West Yorkshire, LS97TF

  • King's College Hospital, London

    London, SE5 9RS

Other trials in United Kingdom

France1 site

  • Hopital Saint-Louis - APHP

    Paris, Île-de-France Region, 75010

Other trials in France

About this study

Official title: A Phase 1/2 Study of REGN7257 (Anti-Interleukin 2 Receptor Subunit Gamma [IL2RG] Monoclonal Antibody) in Patients With Severe Aplastic Anemia That Is Refractory to or Relapsed on Immunosuppressive Therapy

This study is researching an experimental drug called REGN7257 (called "study drug"). The study is focused on patients who have severe aplastic anemia (SAA), a disease of the bone marrow resulting in an impairment of the production of blood cells.

The main purpose of this two-part study (Part A and Part B) is to test how safe and tolerable REGN7257 is in patients with SAA in which other Immunosuppressive therapies (ISTs) have not worked well.

Read more

The study is looking at several other research questions to better understand the following properties of REGN7257:

  • Side effects that may be experienced by participants taking REGN7257
  • How REGN7257 works in the body
  • How much REGN7257 is present in blood after dosing
  • If REGN7257 works to raise levels of certain blood counts after treatment
  • How quickly REGN7257 works to raise levels of certain blood counts
  • In patients for whom REGN7257 works to raise levels of certain blood counts after treatment, how many continue to show such a response throughout the study
  • If REGN7257 works to lower the number of platelet and red blood cell transfusions needed
  • How REGN7257 changes immune cell counts and composition
  • How the body reacts to REGN7257 and if it produces proteins that bind to REGN7257 (this would be called the formation of anti-drug antibodies [ADA])
Read the detailed description

The trial was intended to be a Phase 1/2 trial, but no participants were enrolled in Phase 2

Being tested
REGN7257
Keywords
Immunosuppressive therapy (IST), Refractory, Relapsed
Medical subject headings
Anemia, Aplastic, Recurrence

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • REGN7257Drug

    Administered by intravenous (IV) infusion, in Part A and B.

Study groups in NCT04409080
Study groupRoleWhat they receive
Part AExperimentalPart A: Single ascending dose (SAD) escalation cohorts
Receives: Drug: REGN7257
Part BExperimentalPart B: Multiple REGN7257 dosages.
Receives: Drug: REGN7257

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Incidence of adverse events (AEs)

    Part A

    Measured: 12 months post-treatment, approximately 52 weeks

  2. Incidence of serious adverse events (SAEs)

    Part A

    Measured: 12 months post-treatment, approximately 52 weeks

  3. Incidence and severity of treatment-emergent adverse events (TEAEs)

    Part A

    Measured: 12 months post-treatment, approximately 52 weeks

  4. Incidence of serious adverse events (SAEs)

    Part B

    Measured: Through the end of study visit, approximately 78 weeks

  5. Incidence and severity of treatment-emergent adverse events (TEAEs)

    Part B

    Measured: Through the end of study visit, approximately 78 weeks

  6. Overall response rate (ORR)

    Part B

    Measured: At 6 months, approximately 26 weeks

Secondary outcomes (33)

  1. ORR

    Parts A and B

    Measured: At 3 months, approximately 12 weeks

  2. Complete response (CR)

    Parts A and B

    Measured: At 3 months, approximately 12 weeks

  3. Partial response (PR)

    Parts A and B

    Measured: At 3 months, approximately 12 weeks

  4. Time to best response

    Part A

    Measured: Up to 12 months

  5. Time to best response

    Part B

    Measured: Up to 18 months

  6. Time to first response

    Part A

    Measured: Up to 12 months

  7. Time to first response

    Part B

    Measured: Up to 18 months

  8. Any clinical response

    Part A

    Measured: Until the end of study, approximately week 52

  9. Any clinical response

    Part B

    Measured: Until the end of study, approximately week 78

  10. Platelet transfusions per month over time

    Part A

    Measured: Up to 12 months

  11. Platelet transfusions per month over time

    Part B

    Measured: Up to 18 months

  12. Red blood cell transfusions per month over time

    Part A

    Measured: Up to 12 months

  13. Red blood cell transfusions per month over time

    Part B

    Measured: Up to 18 months

  14. Changes in lymphocyte cell counts

    Part A

    Measured: Up to 12 months

  15. Changes in lymphocyte cell counts

    Part B

    Measured: Up to 18 months

  16. Changes in neutrophil cell counts

    Part A

    Measured: Up to 12 months

  17. Changes in neutrophil cell counts

    Part B

    Measured: Up to 18 months

  18. Changes in hemoglobin cell counts

    Part A

    Measured: Up to 12 months

  19. Changes in hemoglobin cell counts

    Part B

    Measured: Up to 18 months

  20. Changes in reticulocyte cell counts

    Part A

    Measured: Up to 12 months

  21. Changes in reticulocyte cell counts

    Part B

    Measured: Up to 18 months

  22. Changes in platelet cell counts

    Part A

    Measured: Up to 12 months

  23. Changes in platelet cell counts

    Part B

    Measured: Up to 18 months

  24. Changes in the whole blood immune cell subsets (T cells)

    Part A

    Measured: Up to 12 months

  25. Changes in the whole blood immune cell subsets (T cells)

    Part B

    Measured: Up to 18 months

  26. Changes in the whole blood immune cell subsets (B cells)

    Part A

    Measured: Up to 12 months

  27. Changes in the whole blood immune cell subsets (B cells)

    Part B

    Measured: Up to 18 months

  28. Changes in the whole blood immune cell subsets [Natural killer (NK) cells]

    Part A

    Measured: Up to 12 months

  29. Changes in the whole blood immune cell subsets (NK cells)

    Part B

    Measured: Up to 18 months

  30. Drug concentrations in serum over time

    Part A

    Measured: Up to 12 months

  31. Drug concentrations in serum over time

    Part B

    Measured: Up to 18 months

  32. Incidence of treatment-emergent anti-drug antibody (ADA) over time

    Part A

    Measured: Up to 12 months

  33. Incidence of treatment-emergent ADA over time

    Part B

    Measured: Up to 18 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted1 Jun 2020
  2. Study start13 Jan 2021
  3. Primary completion17 Oct 2024
  4. Study completion17 Oct 2024

Why it stopped: Sponsor Decision

Resources

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 1
Primary purpose
Treatment
Allocation
Non-randomised
Intervention model
Sequential
Masking
None (open label)
Enrolment
17 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04409080
Sponsor's protocol ID
R7257-RAA-1947
Other IDs
2020-002031-29, 2023-508601-24-00, 2023
Status last verified
Jun 2026
First submitted
26 May 2020
Last updated
22 Jun 2026
Results posted
No
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

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing REGN7257 in people with Severe Aplastic Anemia (SAA), run by Regeneron Pharmaceuticals at 10 sites in 4 countries.

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 4 inclusion and 10 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: stopped early, as of the sponsor's last update on 22 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 10 sites in South Korea, United States, United Kingdom, France. 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 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study was stopped early (reason given: Sponsor Decision). Results are not available in the source record.

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?

Incidence of adverse events (AEs) (time frame: 12 months post-treatment, approximately 52 weeks). The study lists 6 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04409080.

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 22 Jun 2026.

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