Imaging of cell-based therapy using 89Zr-oxine ex vivo cell labeling for positron emission tomography

Abstract

With the rapid development of anti-cancer cell-based therapies, such as adoptive T cell therapies using tumor-infiltrating T cells, T cell receptor transduced T cells, and chimeric antigen receptor T cells, there has been a growing interest in imaging technologies to non-invasively track transferred cells in vivo. Cell tracking using ex vivo cell labeling with positron emitting radioisotopes for positron emission tomography (PET) imaging has potential advantages over single-photon emitting radioisotopes. These advantages include intrinsically higher resolution, higher sensitivity, and higher signal-to-background ratios. Here, we review the current status of recently developed Zirconium-89 (⁸⁹Zr)-oxine ex vivo cell labeling with PET imaging focusing on its applications and future perspectives. Labeling of cells with ⁸⁹Zr-oxine is completed in a series of relatively simple steps, and its low radioactivity doses required for imaging does not interfere with the proliferation or function of the labeled immune cells. Preclinical studies have revealed that ⁸⁹Zr-oxine PET allows high-resolution in vivo tracking of labeled cells for 1-2 weeks after cell transfer both in mice and non-human primates. These results provide a strong rationale for the clinical translation of ⁸⁹Zr-oxine PET-based imaging of cell-based therapy.

Keywords: Zirconium-89; Zirconium-89 oxine; cell tracking; cell-based therapy; positron emission tomography.

Figure 1

Tracking of transferred cells using ⁸⁹Zr-oxine PET in murine models. A) Activated OT-1 CD8 T cells distribute to antigen-expressing B16-OVA tumor (white dashed circle), while naïve OT-1 CD8 T cells do not. Naïve OT-1 CD8 T cells (left) and activated OT-1 CD8 T cells (right, adapted from 40) were labeled with ⁸⁹Zr-oxine (222 kBq/8 x 10⁶ cells and 248.5 kBq/7.7 x 10⁶ cells, respectively) and intravenously transferred to tumor-bearing recipient mice. PET/CT images acquired on 2nd day after transfer are shown. Also note the different distribution between naïve and activated OT-1 CD8 T cells outside the tumor. B) Activated OT-1 CD8 T cells distribute to antigen-expressing B16-OVA tumor (cyan circle) but not to antigen-negative B16 tumor (white dashed circle). Activated OT-1 CD8 T cells labeled with ⁸⁹Zr-oxine (185 kBq/8 x 10⁶ cells) were intravenously transferred to the recipient. MicroPET/CT images acquired on 4th day after transfer are shown. Left: maximum intensity projection MIP PET/CT, right: transverse plane. C) Distribution of transferred bone marrow cells. Donor bone marrow cells were labeled with ⁸⁹Zr-oxine (16.6 kBq/2.0 x 10⁷ cells) and intravenously transferred to the recipient. PET/CT imaging was performed at indicated time points after transfer, with multiple intramuscular injections of deferoxamine to prevent accumulation of free ⁸⁹Zr within bone. Transferred bone marrow cells initially distribute to the lungs, followed by distribution within 4 hours to the bone marrow, liver, and spleen. Adapted from .

Figure 2

Tracking of transferred cells using ⁸⁹Zr-oxine PET in non-human primate models. A) Distribution of transferred CD34⁺ hematopoietic stem and progenitor cells (HSPCs) in a rhesus macaque. CD34⁺ HSPCs mobilized by plerixafor and G-CSF treatment were labeled with ⁸⁹Zr-oxine and autologously transferred intravenously (44.4 kBq/10⁶ cells, 1.2 x 10⁶ cells/kg). PET/CT was performed longitudinally under continuous infusion of deferoxamine to prevent accumulation of free ⁸⁹Zr within bone. Transferred cells rapidly distribute to the bone marrow, liver, and spleen . B) Distribution of transferred NK cells in a rhesus macaque. NK cells purified from peripheral blood were expanded ex vivo with IL-2, labeled with ⁸⁹Zr-oxine, and autologously transferred intravenously (15.2 kBq/10⁶ cells, 21.9 x 10⁶ cells/kg). Cell migration was longitudinally tracked by PET/CT. Deferoxamine was continuously infused during the entire imaging study. Transferred NK cells initially distribute to the lungs, followed by gradual distribution to the liver and spleen. Little distribution of NK cells to the bone marrow is observed. Adapted from .