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A Ph Ib Study of REGN5678 Plus Cemiplimab in Patients With mCRPC | Clinical Trials | Clareo Health

RECRUITINGPHASE1

A Ph Ib Study of REGN5678 Plus Cemiplimab in Patients With mCRPC

A Phase Ib Clinical Trial to Optimize Risk Benefit of REGN5678 (PSMAxCD28 Bispecific Antibody) Plus Cemiplimab (Anti-PD-1 Monoclonal Antibody) in Patients With Metastatic Castration-resistant Prostate Cancer

NCT06826768•M.D. Anderson Cancer Center

View on ClinicalTrials.gov

Summary

A single-center phase Ib/II dose escalation and dose-expansion clinical trial of REGN5678 plus cemiplimab

Detailed Description

Primary Objectives: * To evaluate the safety and tolerability of REGN5678 (PSMAxCD28 bispecific antibody) plus cemiplimab (anti-PD-1) in patients with mCRPC. * To determine the maximum tolerated dose or potential recommended phase II dose (RP2D) of REGN5678 (PSMAxCD28 bispecific antibody) plus cemiplimab (anti-PD-1) in patients with mCRPC Secondary Objectives: * To evaluate efficacy of REGN5678 plus cemiplimab in patients with mCRPC. * To characterize the PK of REGN5678 alone and in combination with cemiplimab * To assess the immunogenicity of REGN5678 and cemiplimab. Exploratory Objective: • To evaluate immune responses in the prostate TME and peripheral blood after treatment with REGN5678 plus cemiplimab as compared to pre-treatment samples.

Eligibility

Age

18 - No limit years

Sex

MALE

Healthy Volunteers

Inclusion Criteria

•1. Men .18 years of age.
•2. Histologically or cytologically confirmed adenocarcinoma of the prostate without pure small cell carcinoma.
•3. mCRPC with disease progression after at least two lines of systemic therapy, including one line of second-generation anti-androgen therapy, according to one of the following criteria:
•1. PSA progression as defined by a rising PSA level confirmed with an interval of \>1 week between each assessment.
•2. Radiographic disease progression in soft tissue based on RECIST Version 1.1 criteria with PCWG3 modifications with or without PSA progression.
•3. Radiographic disease progression in bone defined as the appearance of 2 or more new bone lesions on bone scan with or without PSA progression.
•NOTE: Prior approved PSMA-targeted therapies \[e.g. 177Lu-PSMA-617\] and immunotherapy (including sipuleucel-T and immune checkpoint therapies) are permitted.
•4. Have had either orchiectomy OR be on luteinizing hormone-releasing hormone (LHRH) agonist or antagonist therapy with serum testosterone \<50 ng/dL AND agree to stay on LHRH agonist or antagonist therapy during the study.
•5. ECOG performance status (PS) grade of 0 or 1.
•6. Adequate organ and bone marrow function documented by:
+36 more criteria

Exclusion Criteria

•1. Currently receiving treatment in another interventional study
•2. Has participated in a study of an investigational drug within 4-weeks of first dose of study therapy.

Locations (1)

The University of Texas M. D. Anderson Cancer Center

Houston, Texas, United States

Key Dates

Start Date

July 9, 2025

Primary Completion Date

May 1, 2027

Completion Date

May 1, 2029

Last Updated

March 4, 2026

Enrollment

ESTIMATED participants

Conditions

Prostate Cancer

Interventions

REGN5678

DRUG

Cemiplimab

DRUG

Contacts

Bilal Siddiqui, MD

CONTACT

(713) 563-4600 basiddiqui@mdanderson.org

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Data Source & Attribution

This clinical trial information is sourced from ClinicalTrials.gov, a service of the U.S. National Institutes of Health.

ClinicalTrials.gov last update: March 4, 2026Data synced to Clareo: March 29, 2026

Modifications: This data has been reformatted for display purposes. Eligibility criteria have been parsed into inclusion/exclusion sections. Location data has been geocoded to enable distance-based search. For the authoritative and most current information, please visit ClinicalTrials.gov.

Neither the United States Government nor Clareo Health make any warranties regarding the data. Check ClinicalTrials.gov frequently for updates.

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A Ph Ib Study of REGN5678 Plus Cemiplimab in Patients With mCRPC

Inclusion Criteria

Exclusion Criteria

A Study of FG-3246 in Participants With Metastatic Castration-Resistant Prostate Cancer (mCRPC)

Measuring the Effects of Talazoparib in Patients With Advanced Cancer and DNA Repair Variations

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