Production and Preclinical evaluation of the ۶۷Ga-CHX-A-DTPA-trastuzumab for HER۲+ breast cancer SPECT Imaging

Radiolabeled monoclonal antibodies have shown great promise for cancer diagnosis and therapy. Approximately ۱۵% to ۲۰% of breast cancers exhibit an overexpression of a growth-promoting protein known as HER۲. In the present study, trastuzumab was conjugated with CHX-A-DTPA (Macrocyclics B-۳۵۵), the average number of the chelator conjugated per mAb was calculated and total concentration was determined by spectrophotometrically. CHX-A-DTPA–trastuzumab was labeled with ۶۷Ga (۱۰ mCi, ۳۷۵ MBq) then Radiochemical purity and immunoreactivity by SKBR۳ cell line and serum stability of ۶۷Ga-CHX-A-DTPA-trastuzumab were determined. The biodistribution studies was performed in female Sprague Dowley rat (۶۷Ga–CHX-A-DTPA–trastuzumab i.v., ۲۰۰ microl, ۲۰۰±۲۰ mCi, ۳۵±۵ μg mAb , ۴, ۲۴, ۴۸ and ۷۲ h). ۶۷Ga-CHX-A-DTPA-trastuzumab was prepared (RCP>۹۸% ± ۰.۵, Specific activity ۴.۱±۰.۷ μCi/μg). Conjugation reaction (c/a) was ۴.۱±۱.۲. Labeling yield was ۹۲.۵% ± ۲.۱. Immunoreaction of ۶۷Ga-CHX-A-DTPA- trastuzumab complex towards HER۲ antigen was determined by RIA and the complex showed high immunoreactivity towards HER۲. In vitro stability showed more than ۹۱%±۲.۶ in the PBS and ۸۱%±۱.۸ in the serum over ۲۴ h. The Immunoreactivity of the radiolabeled anti-HER۲ towards SKBR۳ cell line was done by using Lindmo assay protocol which was found to be ۰.۸۴. The biodistribution of ۶۷Ga–CHX-A-DTPA-trastuzumab complex in normal Sprague Dowley rat at ۴, ۲۴, ۴۸, and ۷۲ h after intravenous administration, expressed as (%ID/g). Biodistribution studies at ۲۴ and ۴۸ h post-injection revealed the similar pattern to the other radiolabeled anti-HER۲ immunoconjugates

کلیدواژه ها:

HER۲ ، Gallium-۶۷ ، Trastuzumab ، CHX-A-DTPA ، breast cancer