Prostate CancerPhase 1NCT06826768
A Ph Ib Study of REGN5678 Plus Cemiplimab in Patients With mCRPC
A Phase 1 study testing REGN5678 and Cemiplimab in people with Prostate Cancer, run by M.D. Anderson Cancer Center at 1 site in United States.
Trial summary
A single-center phase Ib/II dose escalation and dose-expansion clinical trial of REGN5678 plus cemiplimab Read more about this study
- Who is it for?
- Ages 18 years and older, men only
- Conditions the study is for
- Prostate Cancer
- What is being tested?
- REGN5678 and Cemiplimab
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 1 siteUnited States
- Study dates
- 9 Jul 2025to 1 May 2029
- Phase
- Phase 1
- Are there results?
- Not yet: the study is under way
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
- Men only
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Men .18 years of age.
- Histologically or cytologically confirmed adenocarcinoma of the prostate without pure small cell carcinoma.
- 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:
- PSA progression as defined by a rising PSA level confirmed with an interval of >1 week between each assessment.
- Radiographic disease progression in soft tissue based on RECIST Version 1.1 criteria with PCWG3 modifications with or without PSA progression.
- Radiographic disease progression in bone defined as the appearance of 2 or more new bone lesions on bone scan with or without PSA progression.
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- NOTE: Prior approved PSMA-targeted therapies [e.g. 177Lu-PSMA-617] and immunotherapy (including sipuleucel-T and immune checkpoint therapies) are permitted.
- 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.
- ECOG performance status (PS) grade of 0 or 1.
- Adequate organ and bone marrow function documented by:
- Hemoglobin .8.5 g/dL
- Absolute neutrophil count .1.0 x 109/L
- Platelet count .100 x 109/L
- Serum creatinine .1.5 x ULN or estimated glomerular filtration rate >50 mL/min/1.73 m2.
- Adequate hepatic function:
- Total bilirubin .1.5 x ULN
- AST .2.5 x ULN
- ALT .2.5 x ULN
- Alkaline Phosphatase (ALP) .2.5 x ULN (.5 x ULN if tumor liver or bone involvement).
- NOTES: Patients with Gilbert fs syndrome do not need to meet total bilirubin requirements provided their total bilirubin is not greater than their historical level. Gilbert fs syndrome must be documented appropriately as past medical history.
- Consent to MD Anderson laboratory protocols PA13-0291 and Lab02-152.
- Willing and able to comply with clinic visits and study-related procedures including provision of tumor tissue.
- Provide informed consent signed by study patient.
- To avoid risk of drug exposure through the ejaculate (even men with vasectomies), subjects must use a condom during sexual activity while on study drug and for 6 months following the last dose of study drug. If the subject is engaged in sexual activity with a woman of childbearing potential, a condom is required along with another effective contraceptive method consistent with local regulations regarding the use of birth control methods for subjects participating in clinical studies and their partners. Donation of sperm is not allowed while on study drug and for 6 months following the last dose of study drug.
Who cannot join
- Currently receiving treatment in another interventional study
- Has participated in a study of an investigational drug within 4-weeks of first dose of study therapy.
- Has received treatment with an approved systemic therapy within 3 weeks of dosing or has not yet recovered (ie, grade .1 or baseline) from any acute toxicities except for laboratory changes as described in inclusion criteria or patients with grade 2< neuropathy.
- Has received radiation therapy or major surgery within 14 days of first administration of study drug or has not recovered (ie, grade .1 or baseline) from AEs, except for laboratory changes as described in inclusion criteria or patients with grade .2 neuropathy.
- Has received any previous systemic biologic therapy within 5 half-lives of first dose of study therapy.
- NOTE: Prior treatment with sipuleucel-T is permitted
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- Patients who have not recovered (ie, grade .1 or baseline) from immune-mediated AEs 3 months prior to initiation of study drug therapy except for endocrinopathies adequately managed with hormone replacement.
- Another malignancy that is progressing or requires active treatment, except:
- Non-melanoma skin cancer that has undergone potentially curative therapy
- Any tumor that has been deemed to be effectively treated with definitive local control (with or without continued adjuvant hormonal therapy)
- Concurrent treatment with systemic corticosteroids (prednisone dose >10 mg per day or equivalent) or other immunosuppressive drugs <14 days prior to treatment initiation. Steroids that are topical, inhaled, nasal (spray), or ophthalmic solution are permitted.
- History of or known or suspected autoimmune disease (exception(s): subjects with vitiligo, resolved childhood atopic dermatitis, hypothyroidism, or hyperthyroidism that is clinically euthyroid at screening are allowed).
- Known evidence of an active infection requiring systemic therapy such as human immunodeficiency virus (HIV), active hepatitis, or fungal infection. Testing for hepatitis B and C infection will be performed at screening if not previously performed and documented.
- History of clinically significant cardiovascular disease including, but not limited to:
- Myocardial infarction or unstable angina .6 months prior to treatment initiation
- Clinically significant cardiac arrhythmia
- Deep vein thrombosis, pulmonary embolism, stroke .6 months prior to treatment initiation
- Congestive heart failure (New York Heart Association class III-IV)
- Pericarditis/clinically significant pericardial effusion
- Myocarditis
- Other prior malignancy (exceptions: adequately treated basal cell or squamous cell skin cancer, superficial bladder cancer, or any other cancer in situ currently in complete remission) .2 years prior to enrollment.
- Encephalitis, meningitis, neurodegenerative disease (with the exception of mild dementia that does not interfere with activities of daily living [ADLs]) or uncontrolled seizures in the year prior to first dose of study therapy.
- Known history of, or any evidence of interstitial lung disease, or active, non-infectious pneumonitis (past 5 years).
- Receipt of a live vaccine within 4 weeks of planned start of study medication.
- Prior allogeneic stem cell transplantation or recipients of organ transplants at any time, or autologous stem cell transplantation within 12 weeks of the start of study treatment.
- Any medical, psychological or social condition that in the opinion of the investigator, would preclude participation in this study.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
The University of Texas M. D. Anderson Cancer Center
Houston, Texas, 77030
Bilal Siddiqui, MD, 713-563-4600, basiddiqui@mdanderson.org
Bilal Siddiqui, MD
About this study
Official title: 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
A single-center phase Ib/II dose escalation and dose-expansion clinical trial of REGN5678 plus cemiplimab
Read the 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.
- Conditions
- Prostate Cancer
- Being tested
- REGN5678, Cemiplimab
- Medical subject headings
- Prostatic Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
REGN5678Drug
Given by IV infusion
CemiplimabDrug
Given by IV infusion
| Study group | Role | What they receive |
|---|---|---|
| Treatment with REGN5678 Q3W IV + Cemiplimab Q3W IV | Experimental | Patients will receive three weekly doses of REGN5678 as part of a Lead-In Phase and thentransition to every three-week dosing of the combination of REGN5678 and cemiplimab (anti-PD-1). Receives: Drug: REGN5678; Drug: Cemiplimab |
What is being measured
The primary outcome is the main question the study is designed to answer.
Safety and Adverse Events (AEs
Incidence of Adverse Events, Graded According to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) Version (v) 5.0
Measured: Through study completion; an average of 1 year.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Feb 2025
- Study start9 Jul 2025
- Primary completion1 May 2027 (estimated)
- Study completion1 May 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Prostate CancerStudies of the same condition, open and under way.
- More trials run by M.D. Anderson Cancer CenterThe 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 1
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- M.D. Anderson Cancer Center
- Sponsor type
- University, hospital or other
- Collaborators
- Regeneron Pharmaceuticals
- Responsible party
- Sponsor
- Investigators
- Bilal Siddiqui, MD, Principal investigator, M.D. Anderson Cancer Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06826768
- Sponsor's protocol ID
- 2024-0326
- Other IDs
- NCI-2025-01092
- Status last verified
- Aug 2026
- First submitted
- 10 Feb 2025
- Last updated
- 14 Aug 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 14 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- 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
- ClinicalTrials.gov ID
- NCT06826768
- Acronym / sponsor ID
- 2024-0326
- Conditions
- Prostate Cancer
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 60 participants (estimated)
- Lead sponsor
- M.D. Anderson Cancer CenterUniversity, hospital or other
- Collaborators
- Regeneron Pharmaceuticals
- Study start
- 9 Jul 2025 (actual)
- Primary completion
- 1 May 2027 (estimated)
- Study completion
- 1 May 2029 (estimated)
- First posted
- 14 Feb 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Treatment with REGN5678 Q3W IV + Cemiplimab Q3W IV | Experimental | Drug: REGN5678, Drug: CemiplimabPatients will receive three weekly doses of REGN5678 as part of a Lead-In Phase and thentransition to every three-week dosing of the combination of REGN5678 and cemiplimab (anti-PD-1). |
Who may qualify
- Ages
- 18 years and older
- Sex
- Male only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (24 listed)
- Men .18 years of age.
- Histologically or cytologically confirmed adenocarcinoma of the prostate without pure small cell carcinoma.
- 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:
- NOTE: Prior approved PSMA-targeted therapies [e.g. 177Lu-PSMA-617] and immunotherapy (including sipuleucel-T and immune checkpoint therapies) are permitted.
- 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.
Key exclusion criteria (26 listed)
- Currently receiving treatment in another interventional study
- Has participated in a study of an investigational drug within 4-weeks of first dose of study therapy.
- Has received treatment with an approved systemic therapy within 3 weeks of dosing or has not yet recovered (ie, grade .1 or baseline) from any acute toxicities except for laboratory changes as described in inclusion criteria or patients with grade 2< neuropathy.
- Has received radiation therapy or major surgery within 14 days of first administration of study drug or has not recovered (ie, grade .1 or baseline) from AEs, except for laboratory changes as described in inclusion criteria or patients with grade .2 neuropathy.
- Has received any previous systemic biologic therapy within 5 half-lives of first dose of study therapy.
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 |
|---|---|---|
| REGN5678Given by IV infusion | Drug | Treatment with REGN5678 Q3W IV + Cemiplimab Q3W IV |
| CemiplimabGiven by IV infusion | Drug | Treatment with REGN5678 Q3W IV + Cemiplimab Q3W IV |
Primary outcome
Safety and Adverse Events (AEs
Time frame: Through study completion; an average of 1 year.
Incidence of Adverse Events, Graded According to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) Version (v) 5.0
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 14 Aug 2026.
- MD Anderson Cancer Center WebsiteLink provided by the sponsor.
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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.
Bilal Siddiqui, MD principal investigator
M.D. Anderson Cancer Center
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing REGN5678 and Cemiplimab in people with Prostate Cancer, run by M.D. Anderson Cancer Center at 1 site in United States.
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 24 inclusion and 26 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: looking for participants now, as of the sponsor's last update on 14 Aug 2026. 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 States. 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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Bilal Siddiqui, MD ((713) 563-4600, basiddiqui@mdanderson.org), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Safety and Adverse Events (AEs (time frame: Through study completion; an average of 1 year.). 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 14 Aug 2026.