Molecular Imaging of Chimeric Antigen Receptor T Cells by ICOS-ImmunoPET. Clinical cancer research : an official journal of the American Association for Cancer Research Simonetta, F., Alam, I. S., Lohmeyer, J. K., Sahaf, B., Good, Z., Chen, W., Xiao, Z., Hirai, T., Scheller, L., Engels, P., Vermesh, O., Robinson, E., Haywood, T., Sathirachinda, A., Baker, J., Malipatlolla, M. B., Schultz, L. M., Spiegel, J. Y., Lee, J. T., Miklos, D. B., Mackall, C. L., Gambhir, S. S., Negrin, R. 2020

Abstract

PURPOSE: Immunomonitoring of chimeric antigen receptor (CAR) T cells relies primarily on their quantification in the peripheral blood, which inadequately quantifies their biodistribution and activation status in the tissues. Non-invasive molecular imaging of CAR T cells by positron emission tomography (PET) is a promising approach with the ability to provide spatial, temporal and functional information. Reported strategies rely on the incorporation of reporter transgenes or ex vivo biolabeling, significantly limiting the application of CAR T cell molecular imaging. In the present study, we assessed the ability of antibody-based PET (immunoPET) to non-invasively visualize CAR T cells.EXPERIMENTAL DESIGN: After analyzing human CAR T cells in vitro and ex vivo from patient samples to identify candidate targets for immunoPET, we employed a syngeneic, orthotopic murine tumor model of lymphoma to assess the feasibility of in vivo tracking of CAR T cells by immunoPET using the 89Zr-DFO-anti-ICOS tracer we previously reported.RESULTS: Analysis of human CD19-CAR T cells during activation identified the Inducible T-cell COStimulator (ICOS) as a potential target for immunoPET. In a preclinical tumor model, 89Zr-DFO-ICOS mAb PET-CT imaging detected significantly higher signal in specific bone marrow-containing skeletal sites of CAR T cell treated mice compared with controls. Importantly, administration of ICOS-targeting antibodies at tracer doses did not interfere with CAR T cell persistence and function.CONCLUSIONS: This study highlights the potential of ICOS-immunoPET imaging for monitoring of CAR T cell therapy, a strategy readily applicable to both commercially available and investigational CAR T cells.

View details for DOI 10.1158/1078-0432.CCR-20-2770

View details for PubMedID 33087332