A Study of ImmunoPet Imaging Using 89Zr-DFO-REGN5054 in Adult Participants With Solid Cancers Treated With Cemiplimab

A First-in-Human Study of 89Zr-DFO-REGN5054 (Anti-CD8) Positron Emission Tomography in Patients With Solid Malignancies Treated With Cemiplimab

This study is researching an experimental drug called 89Zr-DFO-REGN5054 and cemiplimab. The study is focused on patients with a type of cancer that can be potentially imaged using 89Zr-DFO-REGN5054 and show special tumor features that may be important to the way the immune system fights cancer.

The aim of the study is to study the safety and tolerability (how the body reacts to the drug) of the imaging agent 89Zr-DFO REGN5054.

The study is looking at several other research questions, including:

• What side effects may happen from taking the study drugs
• How much study drug is in the blood at different times
• Whether the body makes antibodies against the study drugs (which could make the study drugs less effective or could lead to side effects)

Study Overview

• Status: Recruiting
• Conditions: Advanced Solid Tumor; Metastatic Solid Tumor
• Intervention / Treatment: Drug: 89Zr˗DFO˗REGN5054; Drug: cemiplimab

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Clinical Trials Administrator; Phone Number: 844-734-6643; Email: clinicaltrials@regeneron.com

Study Locations

• Netherlands
  • Groningen, Netherlands, 9700 RB
    • Recruiting
    • UMC Groningen

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Key Inclusion Criteria:

• Advanced or metastatic solid tumors that may respond to anti-programmed cell death 1 (PD-1) immunotherapy
• Measurable disease according to Response Evaluation Criteria in Solid Tumours (RECIST) 1.1 criteria
• Eastern Cooperative Oncology Group (ECOG) performance status of ≤1
• Adequate organ and bone marrow function as defined in the protocol
• Willing and able to comply with clinic visits and study-related procedures (including required tumor biopsy for Part B)

Key Exclusion Criteria:

• Currently receiving another cancer treatment or inadequate time since last therapy, as defined in the protocol
• Has not yet recovered from acute toxicities from prior therapy; exceptions defined in the protocol
• Prior treatment with a blocker of the PD-1/Programmed death ligand 1 (PD-L1) pathway
• Currently receiving or has received chimeric antigen receptor (CAR-T) cell therapy
• Symptomatic or untreated brain metastases, leptomeningeal disease, or spinal cord compression
• Known history of or any evidence of interstitial lung disease, active, noninfectious pneumonitis (past 5 years) or active tuberculosis

NOTE: Other protocol defined inclusion/exclusion criteria apply.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Single ascending dose of 89Zr˗DFO˗REGN5054 followed by fixed dose of cemiplimab; Part A: Doses of 89Zr˗DFO˗REGN5054 may be reduced based upon assessment.	Drug: 89Zr˗DFO˗REGN5054; Administered by intravenous (IV) infusion during Part A and B.; Drug: cemiplimab; Administered by IV infusion every 3 weeks (Q3W).; Other Names: REGN2810; Libtayo
Experimental: Defined dose of 89Zr˗DFO˗REGN5054 followed by fixed dose of cemiplimab; Part B: Defined dose of 89Zr˗DFO˗REGN5054 determined in Part A.	Drug: 89Zr˗DFO˗REGN5054; Administered by intravenous (IV) infusion during Part A and B.; Drug: cemiplimab; Administered by IV infusion every 3 weeks (Q3W).; Other Names: REGN2810; Libtayo

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence and severity of treatment-emergent adverse events (TEAEs)	Part A	Up to day 8, after the infusion of 89Zr˗DFO˗REGN5054
Incidence and severity of TEAEs	Part A and B	Up to approximately week 115

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Clinical dosimetry based on tissue radiation effective dose calculated from PET image acquisition data	After injection of 37 MBq of 89Zr-DFO-REGN5054, a series of whole-body PET images will be obtained over a period of up to 8 days and corrected for attenuation by low-dose CT scans using PET/CT. The radiation effective dose for the whole body will be calculated using OLINDA/EXM software. The unit of effective dose will be millisievert per MBq for the whole body for each participant. The final values will be averaged across participants for each mass dose.	On days 1, 5 and 8
Concentration of 89Zr-DFO-REGN5054 in serum	Part A	On days 1, 5 and 8
89Zr-DFO-REGN5054 uptake across cluster of differentiation 8 (CD8)-expressing normal tissues and tumors	Part A and Part B	At the time of imaging, up to day 8
Blood pool uptake of 89Zr-DFO-REGN5054 with subsequent calculation of standardized uptake value (SUV) tumor-to-blood ratios	Part A and Part B	At the time of imaging, up to day 8
Association of 89Zr˗DFO˗REGN5054 autoradiographic signal intensity distribution with CD8 expression in tumor tissues	Part A and Part B	At Baseline
Association of 89Zr-DFO-REGN5054 uptake with CD8 expression in tumor tissues	Part B	At Baseline
Association of tumor-to-blood ratio of 89Zr-DFO-REGN5054 with CD8 expression in tumor tissues	Part B	At Baseline
Clinical dosimetry based on tissue radiation absorbed dose calculated from positron emission tomography (PET) image acquisition data	After injection of 37 megabecquerel (MBq) of 89Zr-DFO-REGN5054, a series of whole-body positron emission tomography (PET) images will be obtained over a period of up to 8 days and corrected for attenuation by low-dose computed tomography (CT) scans using PET/CT. The radiation effective dose per organ/tissue will be calculated for each organ using Organ Level INternal Dose Assessment/EXponential Modeling (OLINDA/EXM). The unit of effective dose per organ/tissue will be millisievert per Minimum Base Quantity (MBq) for each participant's organ/tissue. The final values for each organ will be averaged across participants for each mass dose	On days 1, 5 and 8
Serum imaging agent activity concentration of area under the curve (AUC0-7)	Part A	Up to day 8

Collaborators and Investigators

• Sponsor: Regeneron Pharmaceuticals
• Investigators: Study Director: Clinical Trials Management, Regeneron Pharmaceuticals

Study record dates

Study Major Dates

• Study Start (Actual): February 7, 2023
• Primary Completion (Estimated): January 6, 2027
• Study Completion (Estimated): January 6, 2027

Study Registration Dates

• First Submitted: January 24, 2022
• First Submitted That Met QC Criteria: February 22, 2022
• First Posted (Actual): February 28, 2022

Study Record Updates

• Last Update Posted (Estimated): September 11, 2025
• Last Update Submitted That Met QC Criteria: September 4, 2025
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Keywords: Positron Emission Tomography (PET) scan; Immuno-PET
• Additional Relevant MeSH Terms: Pathologic Processes; Neoplasms; Neoplastic Processes; Pathological Conditions, Signs and Symptoms; Neoplasm Metastasis; Antineoplastic Agents, Immunological; Antineoplastic Agents; cemiplimab
• Other Study ID Numbers: R5054-ONC-1843; 2019-001604-38 (EudraCT Number); 2024-515351-37-00 (Ctis: EUCT Number)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing

IPD Sharing 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

• IPD Sharing 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
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No