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

• 89Zr˗DFO˗REGN5054 (Drug): Administered by intravenous (IV) infusion during Part A and B.
• cemiplimab (Drug), also known as REGN2810, Libtayo: Administered by IV infusion every 3 weeks (Q3W).

Primary outcomes

• Incidence and severity of treatment-emergent adverse events (TEAEs) [Up to day 8, after the infusion of 89Zr˗DFO˗REGN5054]: Part A
• Incidence and severity of TEAEs [Up to approximately week 115]: Part A and B

Secondary outcomes

• Clinical dosimetry based on tissue radiation absorbed dose calculated from positron emission tomography (PET) image acquisition data [On days 1, 5 and 8]: 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
• Clinical dosimetry based on tissue radiation effective dose calculated from PET image acquisition data [On days 1, 5 and 8]: 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.
• Concentration of 89Zr-DFO-REGN5054 in serum [On days 1, 5 and 8]: Part A
• Serum imaging agent activity concentration of area under the curve (AUC0-7) [Up to day 8]: Part A
• 89Zr-DFO-REGN5054 uptake across cluster of differentiation 8 (CD8)-expressing normal tissues and tumors [At the time of imaging, up to day 8]: Part A and Part B
• Blood pool uptake of 89Zr-DFO-REGN5054 with subsequent calculation of standardized uptake value (SUV) tumor-to-blood ratios [At the time of imaging, up to day 8]: Part A and Part B
• Association of 89Zr˗DFO˗REGN5054 autoradiographic signal intensity distribution with CD8 expression in tumor tissues [At Baseline]: Part A and Part B
• Association of 89Zr-DFO-REGN5054 uptake with CD8 expression in tumor tissues [At Baseline]: Part B
• Association of tumor-to-blood ratio of 89Zr-DFO-REGN5054 with CD8 expression in tumor tissues [At Baseline]: Part B

Sex: All, ages: 18 Years to any

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.

• Clinical Trials Management, Study director, Regeneron Pharmaceuticals

NIH grants: 2019