Position for Site-Specific Attachment of a DOTA Chelator to Synthetic Affibody Molecules Has a Different Influence on the Targeting Properties of 68Ga- Compared to 111In-Labeled Conjugates.
2014 (English)In: Molecular Imaging, ISSN 1535-3508, E-ISSN 1536-0121, Vol. 13, 1-12 p.Article in journal (Refereed) Published
AbstractAffibody molecules, small (7 kDa) scaffold proteins, are a promising class of probes for radionuclide molecular imaging. Radiolabeling of Affibody molecules with the positron-emitting nuclide 68Ga would permit the use of positron emission tomography (PET), providing better resolution, sensitivity, and quantification accuracy than single-photon emission computed tomography (SPECT). The synthetic anti-HER2 ZHER2:S1 Affibody molecule was conjugated with DOTA at the N-terminus, in the middle of helix 3, or at the C-terminus. The biodistribution of 68Ga- and 111In-labeled Affibody molecules was directly compared in NMRI nu/nu mice bearing SKOV3 xenografts. The position of the chelator strongly influenced the biodistribution of the tracers, and the influence was more pronounced for 68Ga-labeled Affibody molecules than for the 111In-labeled counterparts. The best 68Ga-labeled variant was 68Ga-[DOTA-A1]-ZHER2:S1, which provided a tumor uptake of 13 ± 1 %ID/g and a tumor to blood ratio of 39 ± 12 at 2 hours after injection. 111In-[DOTA-A1]-ZHER2:S1 and 111In-[DOTA-K58]-ZHER2:S1 were equally good at this time point, providing a tumor uptake of 15 to 16 %ID/g and a tumor to blood ratio in the range of 60 to 80. In conclusion, the selection of the best position for a chelator in Affibody molecules can be used for optimization of their imaging properties. This may be important for the development of Affibody-based and other protein-based imaging probes.
Place, publisher, year, edition, pages
2014. Vol. 13, 1-12 p.
Biochemistry and Molecular Biology Radiology, Nuclear Medicine and Medical Imaging
IdentifiersURN: urn:nbn:se:uu:diva-232934DOI: 10.2310/7290.2014.00034PubMedID: 25249017OAI: oai:DiVA.org:uu-232934DiVA: diva2:750256