Methods for the Production of Radiolabeled Bioagents for ImmunoPET

Abstract

Immunoglobulin-based positron emission tomography (ImmunoPET) is making increasingly significant contributions to the nuclear imaging toolbox. The exquisite specificity of antibodies combined with the high-resolution imaging of PET enables clinicians and researchers to localize diseases, especially cancer, with a high degree of spatial certainty. This review focuses on the radiopharmaceutical preparation necessary to obtain those images-the work behind the scenes, which occurs even before the patient or animal is injected with the radioimmunoconjugate. The focus of this methods review will be the chelation of four radioisotopes to their most common and clinically relevant chelators.

Keywords: 124I; 64Cu; 86Y; 89Zr; ImmunoPET; antibody radiolabeling; chelator; radioimmunoconjugate.

Figure 1:

PET imaging with ⁸⁹Zr-DFO-mAb-B43.13. PET images of an athymic nude mouse bearing a CA125-positive OVCAR3 xenograft after the administration of ⁸⁹Zr-DFO-mAb-B43.13 via tail vein injection (10.2–12.0 MBq). Coronal planar images intersect the middle of the tumor. L = liver; T = tumor. This adapted figure was originally published in the Journal of Nuclear Medicine, issue 57(5). (Sharma et al. 2016)

Figure 2:. Site-specific ⁸⁹Zr-DFO-trastuzumab PET/CT imaging in PDX models with varying HER2 expression.

Representative axial PET/CT images of 89Zr-DFO-trastuzumab (endoS2) tumor uptake in ST518 (breast), ST562 (gastric), ST928B (breast), ST2789B (breast) and ST1616B (breast) PDX models 70 hours post-injection. This adapted figure was originally published in the journal Theranostics, issue 9(15). (Kristensen et al. 2019)

Figure 3:

Representative small-animal PET images 72 h after injection of ⁸⁹Zr-cetuximab. Mouse bearing U-373 MG (left) or HT-29 (center) tumors in both flanks. Mouse (right) bearing A-431 and T-47D (circled) tumor in right and left flanks, respectively. Red arrows indicate tumors. Images at mid-plane cross-section through tumor are shown. Images are corrected for injected dose and decay, represented as %ID/mL. High uptake is found in EGFR-expressing tumors (HT-29, U-373 MG, A-431), whereas uptake of low-expression tumor (T-47D) is comparable with overall uptake in surrounding normal tissue. ⁸⁹Zr-cetuximab uptake was also found in catabolic organs: in liver and kidneys (below tumors). This adapted figure was originally published in the Journal of Nuclear Medicine, issue 50(1). (Aerts et al. 2009)

Figure 4:

Coronal PET images of ⁸⁹Zr-DFO-J591 (11.1–12.9 MBq [300–345 μCi] injected via tail vein in 200 μl 0.9% sterile saline) in athymic nude mice bearing subcutaneous, PSMA-expressing LNCaP prostate cancer xenografts (white arrows) between 24 and 120 hr post-injection. This adapted figure was originally published in the Journal of Visualized Experiments, issue 96. (Zeglis and Lewis 2015)

Figure 5:

PET-CT image showing ⁶⁴Cu-pembrolizumab immunoPET in NSG/293 T/hPD-1 mouse model. Representative PET images scanned at 4, 24, and 48 h post-injection of 64Cu-pembrolizumab tracer (7.4 MBq/200 μL) in NSG/293 T/hPD-1-nblk (non-blocking) mice. L liver, H heart, X xenograft, S spleen. This adapted figure was originally published in the journal Scientific Reports, issue 8(1). (Natarajan et al. 2018)

Figure 6:

⁶⁴Cu-NOTA-trastuzumab PET in orthotopic HER2-positive BT-474 breast tumor model. Tumor uptake of ⁶⁴Cu-NOTA-trastuzumab was clearly visible at 6 h and peaked at 51 h. This adapted figure was originally published in the Journal of Nuclear Medicine, issue 60(1). (Woo et al. 2019)

Figure 7:

PET imaging with ^m showing maximum intensity projections of PET and CT imaging with ⁶⁴Cu-TE2A-9E7.4 at 24 h post-injection. This research was originally published in the International Journal of Molecular Sciences, issue 20(10). (Bailly et al. 2019)

Figure 8:

Small animal PET/CT maximum intensity projection images of HCT116 tumor bearing female nude mice at 48 h post-injection 64Cu-CB-TE1A1P–cetuximab. One group of mice was pretreated with ~166–33 equiv of unlabeled cetuximab 24 h prior to probe injection (right panel) while the other group was not pretreated (left panel). This adapted figure was originally published in Molecular Pharmaceutics, issue 11(11). (Zeng et al. 2014)

Figure 9:

Coronal small animal PET/CT images of mice injected with ch14.18-ΔCH2 labeled with 64Cu via (NH2)(CO2H)sar at 48 h postinjection. PET data is in color scale; CT data is in gray scale. This adapted figure was originally published in Bioconjugate Chemistry, issue 26(4). (Dearling et al. 2015)

Figure 10:

Serial coronal PET images of 2 mice injected with ⁸⁶Y-hu3S193. This adapted figure was originally published in Journal of Nuclear Medicine, issue 42(8). (Lovqvist et al. 2001)

Figure 11:

PET images of FaDu xenograft-bearing nude mouse injected with ¹²⁴I-L19-SIP (3.7 MBq, 25 μg). Coronal images were acquired at 24 (a) and 48 h (b) after injection. Image planes have been chosen where both tumours were visible. Uptake of 124I in the stomach (arrow) and to some extend in bladder (urine) is visible at 24 h p.i., but has disappeared at 48 h p.i. This adapted research was originally published in the European Journal of Nuclear Medicine and Molecular Imaging, issue 36(8). (Tijink et al. 2009)