Safety and Tolerability of REGN17235 in Adult Participants With Clonal Cytopenia of Undetermined Significance and Low-Risk Myelodysplastic Syndrome With SF3B1 Mutation

An Open-Label, Multi-Center Phase I Study to Investigate the Safety and Tolerability of REGN17235 in Patients With Clonal Cytopenia of Undetermined Significance and Low-Risk Myelodysplastic Syndrome With SF3B1 Mutation

Status

Not yet recruiting

Phases

Phase 1

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT07753148

Enrollment

Registered

2026-08-07

Start date

2026-09-17

Completion date

2031-05-05

Last updated

2026-08-07

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Clonal Cytopenia of Undetermined Significance (CCUS), Low-Risk Myelodysplastic Syndrome (LR-MDS)

Keywords

Blood cancer, First in human, Selective elimination of SF3B1-mutant cells

Brief summary

This study will test a study drug called REGN17235 (the "study drug") to see if it can help treat Clonal Cytopenia of Undetermined Significance (CCUS) and Low-Risk Myelodysplastic Syndrome (LR-MDS) with a specific genetic mutation (SF3B1 Mutation). The study is looking at: * What side effects the study drug might cause * How well the study drug works * How much of the study drug is in the blood at different times * If the body makes antibodies (proteins that attach to substances your body does not recognize) against the study drug; this may cause the study drug to not work as well. * What is the best dose of the study drug to treat CCUS and LR-MDS

Interventions

DRUGREGN17235

Administered per the protocol

Study design

Allocation

NON_RANDOMIZED

Intervention model

SINGLE_GROUP

Primary purpose

TREATMENT

Masking

NONE

Intervention model description

Part 1 Single Part 2 Parallel

Eligibility

Sex/Gender

ALL

Age

18 Years to No maximum

Healthy volunteers

Inclusion criteria

Key Inclusion Criteria: 1. Presence of SF3B1 mutation in the bone marrow or peripheral blood AND diagnosis of low-risk MDS OR diagnosis of CCUS as defined by WHO 2022, 5th edition as described in the protocol 2. Adequate bone marrow function as described in the protocol; red blood cell transfusion dependence is permitted 3. Adequate hepatic and renal function as described in the protocol Key

Exclusion criteria

1. Clinically significant anemia due to non-MDS or non-CCUS etiologies (eg, iron deficiency, vitamin B12 or folate deficiency, autoimmune or hereditary hemolysis, or hemorrhage) diagnosed or treated within the last 3 months prior to informed consent 2. Recent or uncontrolled infections as described in the protocol 3. Diagnosed or treated for malignancy other than MDS as described in the protocol 4. Prior treatment with any systemic therapy for MDS or CCUS within 5 half-lives or within 14 days prior to first administration of study drug, whichever is shorter 5. Allogeneic hematopoietic stem cell transplant within 100 days of enrollment or any signs or symptoms of ongoing Graft-Versus Host Disease (GVHD) as described in the protocol Note: Other protocol defined Inclusion/

Design outcomes

Primary

Measure	Time frame
Occurrence of Treatment Emergent Adverse Events (TEAEs)	Up to 5 years
Severity of TEAEs	Up to 5 years
Occurrence of Serious Adverse Events (SAEs)	Up to 5 years
Severity of SAEs	Up to 5 years

Secondary

Measure	Time frame
Hematologic improvement per International Working Group (IWG) 2018	Up to 5 years
Concentration of REGN17235 in serum	Up to 5 years
Occurrence of Anti-Drug Antibodies (ADA) to REGN17235 in serum	Up to 5 years
Magnitude of ADA to REGN17235 in serum	Up to 5 years

Contacts

CONTACTClinical Trials Administrator

clinicaltrials@regeneron.com844-734-6643

STUDY_DIRECTORClinical Trial Management

Regeneron Pharmaceuticals

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Aug 8, 2026