Fully Automated 89 Zr Labeling and Purification of Antibodies

• Published in: Journal of Nuclear Medicine Vol. 60; no. 5; pp. 691 - 695
• Main Authors: Poot, Alex J, Adamzek, Kevin W A, Windhorst, Albert D, Vosjan, Maria J W D, Kropf, Saskia, Wester, Hans-Jurgen, van Dongen, Guus A M S, Vugts, Danielle J
• Format: Journal Article
• Language: English
• Published: United States 01-05-2019
• Subjects: Antibodies, Monoclonal - chemistry; Antibodies, Monoclonal - isolation & purification; Automation; Isotope Labeling - methods; Radioisotopes - chemistry; Radiopharmaceuticals - chemistry; Reproducibility of Results; Zirconium - chemistry; radiopharmaceuticals; 89Zr; automation; positron emission tomography; antibody labeling; good manufacturing practice
• ISSN: 0161-5505; 1535-5667; 2159-662X
• DOI: 10.2967/jnumed.118.217158

Dozens of monoclonal antibodies (mAbs) have been approved for clinical use, and hundreds more are under development. To support these developments and facilitate a personalized medicine approach, PET imaging and quantification of mAbs, after chelation with desferrioxamine B (DFO) and radiolabeling with
Zr, has become attractive. Also, the use of
Zr-mAbs in preclinical and clinical studies is expanding rapidly. Despite these rapid developments,
Zr radiolabeling is still performed manually. Therefore, we aimed to develop a simple, fully automated, good-manufacturing-practice (GMP)-compliant production procedure for the
Zr labeling of mAbs. Such procedures should increase the robustness and capacity of
Zr-mAb production while minimizing the radiation dose to the operator. Here, the procedures for fully automated
Zr-mAb production are described and applied to produce batches of
Zr-DFO-
-suc-cetuximab and
Zr-DFO-
-suc-rituximab suitable for clinical use. Both products had to meet the GMP-compliant quality standards with respect to yield, radiochemical purity, protein integrity, antigen binding, sterility, and endotoxin levels.
Automated
Zr labeling of mAbs was developed on a Scintomics GRP 2V module and comprised the following steps: reagent transfer to the
Zr-containing reaction vial, mixing of the reagents followed by a 60-min reaction at room temperature to obtain optimal radiolabeling yields, and product purification using a PD-10 desalting column.
Radiochemical yields of
Zr-DFO-
-suc-cetuximab and
Zr-DFO-
-suc-rituximab were all more than 90% according to instant thin-layer chromatography. Isolated yields were 74.6% ± 2.0% and 62.6% ± 3.0% for
Zr-DFO-
-suc-cetuximab and
Zr-DFO-
-suc-rituximab, respectively, which are similar to isolated yields obtained using GMP protocols for manual
Zr labeling of mAbs. To meet the GMP-compliant quality standards, only the radiochemically pure fractions were collected from PD-10, resulting in a lower isolated yield than the radiochemical yield according to instant thin-layer chromatography. The radiochemical purity and protein integrity were more than 95% for both products, and the antigen binding was 95.6% ± 0.6% and 87.1% ± 2.2% for
Zr-DFO-
-suc-cetuximab and
Zr-DFO-
-suc-rituximab, respectively. The products were sterile, and the endotoxin levels were within acceptable limits, allowing future clinical production using this procedure.
Procedures for fully automated GMP-compliant production of
Zr-mAbs were developed on a commercially available synthesis module, which also allows the GMP production of other radiolabeled mAbs.