Immuno-PET imaging of tumor-infiltrating lymphocytes using zirconium-89 radiolabeled anti-CD3 antibody in immune-competent mice bearing syngeneic tumors

• Published in: PloS one Vol. 13; no. 3; p. e0193832
• Main Authors: Beckford Vera, Denis R, Smith, Christof C, Bixby, Lisa M, Glatt, Dylan M, Dunn, Stuart S, Saito, Ryoichi, Kim, William Y, Serody, Jonathan S, Vincent, Benjamin G, Parrott, Matthew C
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07.03.2018; Public Library of Science (PLoS)
• Subjects: Animals; Antibodies; Biology and Life Sciences; Butylhydroxybutylnitrosamine; Care and treatment; CD3 Complex - immunology; CD4-Positive T-Lymphocytes - immunology; CD4-Positive T-Lymphocytes - pathology; CD8-Positive T-Lymphocytes - immunology; CD8-Positive T-Lymphocytes - pathology; Cell Line, Tumor; Deferoxamine; Flow Cytometry; Lymphocytes; Lymphocytes, Tumor-Infiltrating - immunology; Lymphocytes, Tumor-Infiltrating - pathology; Medicine and Health Sciences; Mice, Inbred C57BL; Neoplasm Transplantation; Physiological aspects; Positron Emission Tomography Computed Tomography - methods; Radioisotopes; Radiopharmaceuticals; Research and Analysis Methods; Tissue Distribution; Tumors; Urinary Bladder Neoplasms - diagnostic imaging; Urinary Bladder Neoplasms - immunology; Urinary Bladder Neoplasms - pathology; Zirconium
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0193832

The ability to non-invasively monitor tumor-infiltrating T cells in vivo could provide a powerful tool to visualize and quantify tumor immune infiltrates. For non-invasive evaluations in vivo, an anti-CD3 mAb was modified with desferrioxamine (DFO) and radiolabeled with zirconium-89 (Zr-89 or 89Zr). Radiolabeled 89Zr-DFO-anti-CD3 was tested for T cell detection using positron emission tomography (PET) in both healthy mice and mice bearing syngeneic bladder cancer BBN975. In vivo PET/CT and ex vivo biodistribution demonstrated preferential accumulation and visualization of tracer in the spleen, thymus, lymph nodes, and bone marrow. In tumor bearing mice, 89Zr-DFO-anti-CD3 demonstrated an 11.5-fold increase in tumor-to-blood signal compared to isotype control. Immunological profiling demonstrated no significant change to total T cell count, but observed CD4+ T cell depletion and CD8+ T cell expansion to the central and effector memory. This was very encouraging since a high CD8+ to CD4+ T cell ratio has already been associated with better patient prognosis. Ultimately, this anti-CD3 mAb allowed for in vivo imaging of homeostatic T cell distribution, and more specifically tumor-infiltrating T cells. Future applications of this radiolabeled mAb against CD3 could include prediction and monitoring of patient response to immunotherapy.