Re-186-maSGS-Z(HER2:342), a potential Affibody conjugate for systemic therapy of HER2-expressing tumours
2010 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 37, no 2, 260-269 p.Article in journal (Refereed) Published
PURPOSE: Affibody molecules are a novel class of tumour-targeting proteins, which combine small size (7 kDa) and picomolar affinities. The Affibody molecule Z(HER2:342) has been suggested for imaging of HER2 expression in order to select patients for trastuzumab therapy. When optimizing chelators for (99m)Tc-labelling, we have found that synthetic Z(HER2:342) conjugated with mercaptoacetyl-glycyl-glycyl-glycyl (maGGG) and mercaptoacetyl-glycyl-seryl-glycyl (maGSG) chelators provides relatively low renal uptake of radioactivity and could be suitable for therapy. METHODS: maGGG-Z(HER2:342) and maGSG-Z(HER2:342) were labelled with (186)Re and their biodistribution was studied in normal mice. Dosimetric evaluation and tumour targeting to HER2-overexpressed xenografts (SKOV-3) by (186)Re-maGSG-Z(HER2:342) were studied. RESULTS: Gluconate-mediated labelling of maGGG-Z(HER2:342) and maGSG-Z(HER2:342) with (186)Re provided a yield of more than 95% within 60 min. The conjugates were stable and demonstrated specific binding to HER2-expressing SKOV-3 cells. Biodistribution in normal mice demonstrated rapid blood clearance, low accumulation of radioactivity in the kidney and other organs, accumulating free perrhenate. Both (186)Re-maGGG-Z(HER2:342) and (186)Re-maGSG-Z(HER2:342) demonstrated lower renal uptake than their (99m)Tc-labelled counterparts. (186)Re-maGSG-Z(HER2:342) provided the lowest uptake in healthy tissues. Biodistribution of (186)Re-maGSG-Z(HER2:342) in nude mice bearing SKOV-3 xenografts showed specific targeting of tumours. Tumour uptake 24 h after injection (5.84+/-0.54%ID/g) exceeded the concentration in blood by more than 500-fold, and uptake in kidneys by about 8-fold. Preliminary dosimetric evaluation showed that dose-to-tumour should exceed dose-to-kidney by approximately 5-fold. CONCLUSION: Optimization of chelators improves biodistribution properties of rhenium-labelled small scaffold proteins and enables selection of promising radiotherapeutic agents based on the Affibody molecule.
Place, publisher, year, edition, pages
2010. Vol. 37, no 2, 260-269 p.
Rhenium, Affibody molecules, Chelator, Mercaptoacetyl, HER2
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-130218DOI: 10.1007/s00259-009-1268-9ISI: 000274293900008PubMedID: 19771426OAI: oai:DiVA.org:uu-130218DiVA: diva2:348235