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Metastatic Castration-Resistant Prostate Cancer (mCRPC)Phase 1/2NCT07594106

REGN15505 (PSMAx4-1BB) Alone or in Combination With Cemiplimab or REGN4336 (PSMAxCD3) in Adult Patients With Metastatic Castration-Resistant Prostate Cancer and Clear Cell Renal Cell Carcinoma

A Phase 1/2 study testing REGN15505, REGN15505+Cemiplimab and REGN15505+REGN4336 in people with Metastatic Castration-Resistant Prostate Cancer (mCRPC) and Clear Cell Renal Cell Carcinoma (ccRCC), run by Regeneron Pharmaceuticals at 6 sites in United States.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

This study is researching a new drug called REGN15505 when used alone or in combination with cemiplimab or in combination with REGN4336 in adult patients with mCRPC and ccRCC. The goal is to explore new ways to treat these cancers by helping immune cells target and destroy cancer cells. Read more about this study

Who is it for?
Ages 18 years and older
What is being tested?
REGN15505, REGN15505+Cemiplimab and REGN15505+REGN4336
Could I receive a placebo?
No, everyone receives an active treatment
How many people
265 participants
Where
6 sitesUnited States
Study dates
20 Jul 2026to 27 Oct 2030
Phase
Phase 1/2
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
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Participants with mCRPC:
  • Men with histologically or cytologically confirmed adenocarcinoma of the prostate without pure small cell carcinoma
  • mCRPC with PSA value at screening ≥4 ng/mL and that has progressed within 6 months prior to screening as described in the protocol
  • Has received ≥2 lines of prior systemic therapy approved in the metastatic and/or castration-resistant setting as described in the protocol
  • 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
  • Participants with ccRCC:
Show all 9Show fewer
  • Men and women with histologically or cytologically confirmed Renal Cell Carcinoma (RCC) with a clear-cell component
  • Diagnosis of metastatic ccRCC with at least 1 measurable lesion via Response evaluation criteria in solid tumors (RECIST) 1.1 criteria
  • Has progressed on or after ≥1 line of prior systemic therapy approved in the metastatic setting. Prior treatment must include an Anti Program Cell Death 1 (PD-1)/ Program Death Ligand 1 (PD-L1) therapy and either ipilimumab and/or a Tyrosine Kinase Inhibitor (TKI)

Who cannot join

  • For Both mCRPC and ccRCC Cohorts:
  • Has received treatment with an approved systemic therapy (including sipuleucel-T for mCRPC patients) 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 the protocol
  • mCRPC Cohort Only:
  • Has received prior Prostate Specific Membrane Antigen (PSMA)-targeting therapy with the exception of a PSMA-targeting radioligand (eg, 177Lu-PSMA-617)
  • Note: Other protocol defined inclusion/exclusion criteria apply

Trial locations and contacts

6 sites in 1 country. Contact the study team or a site near you to ask about taking part.

Clinical Trials Administrator contact

844-734-6643

clinicaltrials@regeneron.com

6 sites in 1 country

United States6 sites, 6 recruiting

  • City of Hope

    Duarte, California, 91010

    Recruiting

  • City of Hope Phoenix

    Goodyear, Arizona, 85338

    Recruiting

  • The University of Texas MD Anderson Cancer Center

    Houston, Texas, 77030

    Recruiting

  • Washington University

    St Louis, Missouri, 63110

    Recruiting

  • H. Lee Moffitt Cancer Center

    Tampa, Florida, 33612

    Recruiting

  • City of Hope Chicago, City of Hope Cancer Center Chicago

    Zion, Illinois, 60099

    Recruiting

Other trials in United States

About this study

Official title: Phase 1/2 Study of REGN15505 (a PSMAx4-1BB Bispecific Antibody) Administered Alone or in Combination With Cemiplimab or REGN4336 (a PSMAxCD3 Bispecific Antibody) in Patients With Metastatic Castration-Resistant Prostate Cancer and Clear Cell Renal Cell Carcinoma

This study is researching a new drug called REGN15505 when used alone or in combination with cemiplimab or in combination with REGN4336 in adult patients with mCRPC and ccRCC. The goal is to explore new ways to treat these cancers by helping immune cells target and destroy cancer cells.

The study will evaluate the use of REGN15505 when administered alone, in combination with cemiplimab, or in combination with REGN4336 for:

  • Any side effects of study drugs
  • How well the study drugs work
  • How much REGN15505, cemiplimab, and REGN4336 are in the blood at different times
  • If the body makes antibodies to REGN15505 or REGN4336, which may mean the study drugs will not work as well as expected
  • What is the best dose of REGN15505 when administered alone and with cemiplimab and the best dose of REGN15505 and REGN4336 when used in combination
Being tested
REGN15505, REGN15505+Cemiplimab, REGN15505+REGN4336
Keywords
Cemiplimab, PSMA, REGN4336, REGN15505, 4-1BB
Medical subject headings
Carcinoma, Renal Cell

What participants receive

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

  • REGN15505Drug

    Administered per protocol

  • REGN15505+CemiplimabDrug

    Also called REGN2810, Libtayo

    Administered per protocol

  • REGN15505+REGN4336Drug

    Administered per protocol

Study groups in NCT07594106
Study groupRoleWhat they receive
Module 1: MonotherapyExperimentalREGN15505
Receives: Drug: REGN15505
Module 2: Combination 1ExperimentalREGN15505 and Cemiplimab
Receives: Drug: REGN15505+Cemiplimab
Module 3: Combination 2ExperimentalREGN15505 and REGN4336
Receives: Drug: REGN15505+REGN4336

What is being measured

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

  1. Occurrence of Dose Limiting Toxicities (DLTs)

    Dose Escalation

    Measured: Up to 5 years

  2. Occurrence of Treatment-Emergent Adverse Events (TEAEs)

    Dose Escalation

    Measured: Up to 5 years

  3. Occurrence of Serious Adverse Events (SAEs)

    Dose Escalation

    Measured: Up to 5 years

  4. Occurrence of Adverse Events of Special Interest (AESIs)

    Dose Escalation

    Measured: Up to 5 years

  5. Composite Response (CompR) based on ≥50% decline of Prostate Specific Antigen (PSA) and/or confirmed radiographic assessment of complete response (CR) or partial response (PR)

    Dose Expansion-mCRPC

    Measured: Up to 5 years

  6. Objective response per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1

    Dose Expansion-ccRCC

    Measured: Up to 5 years

Secondary outcomes (11)

  1. Occurrence of TEAEs

    Dose Expansion

    Measured: Up to 5 years

  2. Occurrence of SAEs

    Dose Expansion

    Measured: Up to 5 years

  3. Occurrence of AESIs

    Dose Expansion

    Measured: Up to 5 years

  4. CompR based on ≥50% decline of PSA from baseline and/or confirmed radiographic assessment of CR or PR

    Dose Escalation-mCRPC

    Measured: Up to 5 years

  5. Percentage of participants with ≥50% reduction of PSA

    Dose Escalation and Dose Expansion Phases - mCRPC cohorts

    Measured: Up to 5 years

  6. Percentage of participants with ≥90% reduction in PSA

    Dose Escalation and Dose Expansion - mCRPC cohorts

    Measured: Up to 5 years

  7. Concentration of REGN15505 in serum

    Dose Escalation and Expansion

    Measured: Up to 5 years

  8. Occurrence of Anti Drug Antibodies (ADA) against REGN15505

    Dose Escalation and Expansion

    Measured: Up to 5 years

  9. Occurrence of ADA against REGN4336

    Dose Escalation and Expansion

    Measured: Up to 5 years

  10. Magnitude of ADA against REGN15505

    Dose Escalation and Expansion

    Measured: Up to 5 years

  11. Magnitude of ADA against REGN4336

    Dose Escalation and Expansion

    Measured: Up to 5 years

Timeline

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

  1. First posted18 May 2026
  2. Study start20 Jul 2026
  3. Primary completion27 Oct 2030 (estimated)
  4. Study completion27 Oct 2030 (estimated)

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 1/2
Primary purpose
Treatment
Allocation
Non-randomised
Intervention model
Sequential
Masking
None (open label)
Enrolment
265 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07594106
Sponsor's protocol ID
R15505-ONC-24144
Status last verified
Sep 2026
First submitted
11 May 2026
Last updated
28 Sep 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 1/2 study testing REGN15505, REGN15505+Cemiplimab and REGN15505+REGN4336 in people with Metastatic Castration-Resistant Prostate Cancer (mCRPC) and Clear Cell Renal Cell Carcinoma (ccRCC), run by Regeneron Pharmaceuticals at 6 sites 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 9 inclusion and 5 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 28 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 6 sites 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 combined 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.

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

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 Clinical Trials Administrator (844-734-6643, clinicaltrials@regeneron.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Occurrence of Dose Limiting Toxicities (DLTs) (time frame: Up to 5 years). 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 NCT07594106.

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 28 Sep 2026.

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