CClinicalTrials.gg
Sign In
RecruitingNCT07594106Updated Sep 28, 2026

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 interventional study of REGN15505 and REGN15505+Cemiplimab in Metastatic Castration-Resistant Prostate Cancer (mCRPC) and Clear Cell Renal Cell Carcinoma (ccRCC), sponsored by Regeneron Pharmaceuticals. Recruiting at 6 sites in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-28.

Sponsored by Regeneron Pharmaceuticals · Phase 1/2, Interventional, and Treatment

Phase
Phase 1/2
Study type
Interventional
Enrollment
265
Allocation
Non-randomized
Ages
18 Years and older
Sex
All
01

Study 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.

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
02

Conditions studied

  • Metastatic Castration-Resistant Prostate Cancer (mCRPC)
  • Clear Cell Renal Cell Carcinoma (ccRCC)

Keywords

  • Cemiplimab
  • PSMA
  • REGN4336
  • REGN15505
  • 4-1BB
03

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Eligibility criteria

Key Inclusion Criteria:

Participants with mCRPC:

  1. Men with histologically or cytologically confirmed adenocarcinoma of the prostate without pure small cell carcinoma
  2. mCRPC with PSA value at screening ≥4 ng/mL and that has progressed within 6 months prior to screening as described in the protocol
  3. Has received ≥2 lines of prior systemic therapy approved in the metastatic and/or castration-resistant setting as described in the protocol

  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

    Participants with ccRCC:

  5. Men and women with histologically or cytologically confirmed Renal Cell Carcinoma (RCC) with a clear-cell component
  6. Diagnosis of metastatic ccRCC with at least 1 measurable lesion via Response evaluation criteria in solid tumors (RECIST) 1.1 criteria
  7. 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)

Key Exclusion Criteria:

For Both mCRPC and ccRCC Cohorts:

  1. 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:

  2. 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

04

Study design

Phase
Phase 1 / Phase 2
Primary purpose
Treatment
Allocation
Non-randomized
Intervention model
Sequential assignment
Masking
None (open label)
Enrollment
265 participants (estimated)

Study arms

  • Experimental
    Module 1: Monotherapy

    REGN15505

    Drug: REGN15505

  • Experimental
    Module 2: Combination 1

    REGN15505 and Cemiplimab

    Drug: REGN15505+Cemiplimab

  • Experimental
    Module 3: Combination 2

    REGN15505 and REGN4336

    Drug: REGN15505+REGN4336

Interventions

  • DrugREGN15505

    Administered per protocol

  • DrugREGN15505+Cemiplimab

    Administered per protocol

    Also known as: REGN2810, Libtayo

  • DrugREGN15505+REGN4336

    Administered per protocol

05

What researchers measure

Primary outcomes

  1. Occurrence of Dose Limiting Toxicities (DLTs)

    Dose Escalation

    Time frame: Up to 5 years

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

    Dose Escalation

    Time frame: Up to 5 years

  3. Occurrence of Serious Adverse Events (SAEs)

    Dose Escalation

    Time frame: Up to 5 years

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

    Dose Escalation

    Time frame: 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

    Time frame: Up to 5 years

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

    Dose Expansion-ccRCC

    Time frame: Up to 5 years

Secondary outcomes

  1. Occurrence of TEAEs

    Dose Expansion

    Time frame: Up to 5 years

  2. Occurrence of SAEs

    Dose Expansion

    Time frame: Up to 5 years

  3. Occurrence of AESIs

    Dose Expansion

    Time frame: 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

    Time frame: Up to 5 years

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

    Dose Escalation and Dose Expansion Phases - mCRPC cohorts

    Time frame: Up to 5 years

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

    Dose Escalation and Dose Expansion - mCRPC cohorts

    Time frame: Up to 5 years

  7. Concentration of REGN15505 in serum

    Dose Escalation and Expansion

    Time frame: Up to 5 years

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

    Dose Escalation and Expansion

    Time frame: Up to 5 years

  9. Occurrence of ADA against REGN4336

    Dose Escalation and Expansion

    Time frame: Up to 5 years

  10. Magnitude of ADA against REGN15505

    Dose Escalation and Expansion

    Time frame: Up to 5 years

  11. Magnitude of ADA against REGN4336

    Dose Escalation and Expansion

    Time frame: Up to 5 years

06

Study locations

6 of 6 sites recruiting
  • City of Hope Phoenix
    Goodyear, Arizona 85338, United States
    Recruiting
  • City of Hope
    Duarte, California 91010, United States
    Recruiting
  • H. Lee Moffitt Cancer Center
    Tampa, Florida 33612, United States
    Recruiting
  • City of Hope Chicago, City of Hope Cancer Center Chicago
    Zion, Illinois 60099, United States
    Recruiting
  • Washington University
    St Louis, Missouri 63110, United States
    Recruiting
  • The University of Texas MD Anderson Cancer Center
    Houston, Texas 77030, United States
    Recruiting
07

References and documents

Individual participant data

Plan to share: Yes — All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing

Supporting information: Study protocol, Sap, Icf, Csr, Analytic code

No publications or documents are linked to this record.

08

Registry details

Key details

Study ID
NCT07594106
Lead sponsor
Regeneron Pharmaceuticals
Responsible party
Sponsor
First posted
May 18, 2026
Start date
Jul 20, 2026
Primary completion
Oct 27, 2030 (estimated)
Completion
Oct 27, 2030 (estimated)
Last update
Sep 28, 2026

Study contacts

Clinical Trials Administrator
Contact
clinicaltrials@regeneron.com
844-734-6643
Clinical Trial Management
study director · Regeneron Pharmaceuticals

Oversight

Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Interested in this study?

Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.

Contact study team

Follow this study

Get an email when the registry record changes — status, dates, results — or when someone posts here.

Sign in to follow

Discussion

Questions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.

Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.

Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.

Other studies in this condition

Carcinoma, Renal Cell→

Other studies from this sponsor

Regeneron Pharmaceuticals

Start the discussion