TY - JOUR T1 - Optimization of Hapten-Peptide Labeling for Pretargeted ImmunoPET of Bispecific Antibody Using Generator-Produced <sup>68</sup>Ga JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 555 LP - 559 DO - 10.2967/jnumed.110.083568 VL - 52 IS - 4 AU - Habibe Karacay AU - Robert M. Sharkey AU - William J. McBride AU - Edmund A. Rossi AU - Chien-Hsing Chang AU - David M. Goldenberg Y1 - 2011/04/01 UR - http://jnm.snmjournals.org/content/52/4/555.abstract N2 - Bispecific antibody pretargeting is highly sensitive and specific for cancer detection by PET. In this study, the preparation of a high-specific-activity 68Ga-labeled hapten-peptide, IMP288, was evaluated. Methods: IMP288 (DOTA-D-Tyr-D-Lys(histamine-succinyl-glycine [HSG])-D-glu-D-Lys(HSG)-NH2) was added to buffered 68Ga and then heated in boiling water and purified on a reversed-phase cartridge. Tumor-bearing nude mice were used for biodistribution and tumor localization studies. Results: 68Ga-IMP288 was prepared at a starting specific activity up to 1.78 GBq/nmol, with final yields of 0.74 GBq/nmol (decay-corrected) and less than 1% unbound 68Ga. Purification was essential to remove unbound 68Ga and 68Ge breakthrough. Pretargeted animals showed a high 68Ga-IMP288 uptake (27.5 ± 5.8 percentage injected dose per gram), with ratios of 13.6 ± 4.8, 66.8 ± 14.5, and 325.9 ± 61.9 for the kidneys, liver, and blood, respectively, at 1.5 h after peptide injection. Conclusion: High-specific-activity labeling of DOTA-hapten-peptide was obtained from the 68Ga/68Ge generator for approximately 1 y, yielding products suitable for immunoPET. ER -