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

NCT07594106 | Not Yet Recruiting Phase 1 FDA Drug

• 1 other identifier: R15505-ONC-24144
• Study Type: interventional
• Target: 265
• Locations: 0 countries
• Sites: N/A

Brief 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

Conditions

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

Keywords

Cemiplimab; PSMA; REGN4336; REGN15505; 4-1BB

Outcome Measures

Primary Outcomes (6)

• Occurrence of Dose Limiting Toxicities (DLTs)

  Dose Escalation

  Up to 5 years

• Occurrence of Treatment-Emergent Adverse Events (TEAEs)

  Dose Escalation

  Up to 5 years

• Occurrence of Serious Adverse Events (SAEs)

  Dose Escalation

  Up to 5 years

• Occurrence of Adverse Events of Special Interest (AESIs)

  Dose Escalation

  Up to 5 years

• 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

  Up to 5 years

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

  Dose Expansion-ccRCC

  Up to 5 years

Secondary Outcomes (11)

• Occurrence of TEAEs

  Up to 5 years

• Occurrence of SAEs

  Up to 5 years

• Occurrence of AESIs

  Up to 5 years

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

  Up to 5 years

• Percentage of participants with ≥50% reduction of PSA

  Up to 5 years

Study Arms (3)

Module 1: Monotherapy

EXPERIMENTAL

REGN15505

Drug: REGN15505

Module 2: Combination 1

EXPERIMENTAL

REGN15505 and Cemiplimab

Drug: REGN15505+Cemiplimab

Module 3: Combination 2

EXPERIMENTAL

REGN15505 and REGN4336

Drug: REGN15505+REGN4336

Interventions

REGN15505 DRUG

Administered per protocol

Module 1: Monotherapy

REGN15505+Cemiplimab DRUG

Administered per protocol

Also known as: REGN2810, Libtayo

Module 2: Combination 1

REGN15505+REGN4336 DRUG

Administered per protocol

Module 3: Combination 2

Eligibility Criteria

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

You may qualify if:

• 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:
• 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)

You may not qualify if:

• 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)

Sponsors & Collaborators

• Regeneron Pharmaceuticals: lead

MeSH Terms

Conditions

Carcinoma, Renal Cell

Interventions

cemiplimab

Condition Hierarchy (Ancestors)

Adenocarcinoma; Carcinoma; Neoplasms, Glandular and Epithelial; Neoplasms by Histologic Type; Neoplasms; Kidney Neoplasms; Urologic Neoplasms; Urogenital Neoplasms; Neoplasms by Site; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Kidney Diseases; Urologic Diseases; Male Urogenital Diseases

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: SEQUENTIAL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: May 11, 2026
• First Posted: May 18, 2026
• Study Start (Estimated): May 25, 2026
• Primary Completion (Estimated): September 20, 2030
• Study Completion (Estimated): September 20, 2030
• Last Updated: May 18, 2026

Record last verified: 2026-04

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