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

NCT07753148 | Not Yet Recruiting Phase 1

• 2 other identifiers: R17235-HM-241252026-525464-18-00
• Study Type: interventional
• Target: 52
• Locations: 0 countries
• Sites: N/A

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

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

Outcome Measures

Primary Outcomes (4)

• 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 Outcomes (4)

• 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

Study Arms (2)

Part 1 Dose Escalation

EXPERIMENTAL

Drug: REGN17235

Part 2 Safety Expansion

EXPERIMENTAL

Drug: REGN17235

Interventions

REGN17235 DRUG

Administered per the protocol

Part 1 Dose Escalation; Part 2 Safety Expansion

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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
• Adequate bone marrow function as described in the protocol; red blood cell transfusion dependence is permitted
• Adequate hepatic and renal function as described in the protocol

You may not qualify if:

• 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
• Recent or uncontrolled infections as described in the protocol
• Diagnosed or treated for malignancy other than MDS as described in the protocol
• 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
• 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

Sponsors & Collaborators

• Regeneron Pharmaceuticals: lead

MeSH Terms

Conditions

Hematologic Neoplasms

Condition Hierarchy (Ancestors)

Neoplasms by Site; Neoplasms; Hematologic Diseases; Hemic and Lymphatic Diseases

Study Officials

• Clinical Trial Management

  Regeneron Pharmaceuticals

  STUDY DIRECTOR

Central Study Contacts

Clinical Trials Administrator

CONTACT

844-734-6643; clinicaltrials@regeneron.com

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: Part 1 Single Part 2 Parallel

Study Record Dates

• First Submitted: August 3, 2026
• First Posted: August 7, 2026
• Study Start (Estimated): September 17, 2026
• Primary Completion (Estimated): May 5, 2031
• Study Completion (Estimated): May 5, 2031
• Last Updated: August 7, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, CSR, ANALYTIC CODE
• Time Frame: When Regeneron has: * received marketing authorization from major health authorities (e.g., FDA, European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), etc.) for the product and indication or has globally discontinued development of the product for all indications on or after April 2020 and has no plans for future development * made the study results publicly available (e.g., scientific publication, scientific conference, clinical trial registry) * the legal authority to share the data, and * ensured the ability to protect participant privacy
• Access Criteria: Qualified researchers can submit a proposal for access to individual patient or aggregate level data from a Regeneron-sponsored clinical trial through Vivli. Regeneron's Independent Research Request Evaluation Criteria can be found at: https://www.regeneron.com/sites/default/files/Regeneron-External-Data-Sharing-Policy-and-Independent-Research-Request-Evaluation-Criteria.pdf