The bioconjugation and radiosynthesis of 89Zr-DFO-labeled antibodies.
The exceptional affinity, specificity, and selectivity of antibodies make them extraordinarily attractive vectors for tumor-targeted PET radiopharmaceuticals. Due to their multi-day biological half-life, antibodies must be labeled with positron-emitting radionuclides with relatively long physical decay half-lives. Traditionally, the positron-emitting isotopes 124I (t1/2=4.18 d), 86Y (t1/2=14.7 hr), and 64Cu (t1/2=12.7 hr) have been used to label antibodies for PET imaging. More recently, however, the field has witnessed a dramatic increase in the use of the positron-emitting radiometal 89Zr in antibody-based PET imaging agents. 89Zr is a nearly ideal radioisotope for PET imaging with immunoconjugates, as it possesses a physical half-life (t1/2=78.4 hr) that is compatible with the in vivo pharmacokinetics of antibodies and emits a relatively low energy positron that produces high resolution images. Furthermore, antibodies can be straightforwardly labeled with 89Zr using the siderophore-derived chelator desferrioxamine (DFO). In this protocol, the prostate-specific membrane antigen targeting antibody J591 will be used as a model system to illustrate (1) the bioconjugation of the bifunctional chelator DFO-isothiocyanate to an antibody, (2) the radiosynthesis and purification of a 89Zr-DFO-mAb radioimmunoconjugate, and (3) in vivo PET imaging with an 89Zr-DFO-mAb radioimmunoconjugate in a murine model of cancer.
Department of Radiology, Memorial Sloan Kettering Cancer Center.
Brian M
BM
Zeglis
Department of Radiology, Memorial Sloan Kettering Cancer Center; lewisj2@mskcc.org.
Jason S
JS
Lewis
D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D045744:Cell Line, Tumor; D003676:Deferoxamine / Q000737:chemistry; D064593:Heterografts; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry; D008297:Male; D051379:Mice; D008819:Mice, Nude; D049268:Positron-Emission Tomography / Q000379:methods; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging; D011868:Radioisotopes / Q000737:chemistry*; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
D000911:Antibodies, Monoclonal; D018796:Immunoconjugates; D011868:Radioisotopes; D019275:Radiopharmaceuticals; D015040:Zirconium; D003676:Deferoxamine