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Increase in negative charge of 68Ga/chelator complex reduces unspecific hepatic uptake but does not improve imaging properties of HER3-targeting affibody molecules.

ABSTRACT: Upregulation of the human epidermal growth factor receptor type 3 (HER3) is a common mechanism to bypass HER-targeted cancer therapy. Affibody-based molecular imaging has the potential for detecting and monitoring HER3 expression during treatment. In this study, we compared the imaging properties of newly generated 68Ga-labeled anti-HER3 affibody molecules (HE)3-ZHER3-DOTA and (HE)3-ZHER3-DOTAGA with previously reported [68Ga]Ga-(HE)3-ZHER3-NODAGA. We hypothesized that increasing the negative charge of the gallium-68/chelator complex would reduce hepatic uptake, which could lead to improved contrast of anti-HER3 affibody-based PET-imaging of HER3 expression. (HE)3-ZHER3-X (X?=?DOTA, DOTAGA) were produced and labeled with gallium-68. Binding of the new conjugates was specific in HER3 expressing BxPC-3 and DU145 human cancer cells. Biodistribution and in vivo specificity was studied in BxPC-3 xenograft bearing Balb/c nu/nu mice 3?h pi. DOTA- and DOTAGA-containing conjugates had significantly higher concentration in blood than [68Ga]Ga-(HE)3-ZHER3-NODAGA. Presence of the negatively charged 68Ga-DOTAGA complex reduced the unspecific hepatic uptake, but did not improve overall biodistribution of the conjugate. [68Ga]Ga-(HE)3-ZHER3-DOTAGA and [68Ga]Ga-(HE)3-ZHER3-NODAGA had similar tumor-to-liver ratios, but [68Ga]Ga-(HE)3-ZHER3-NODAGA had the highest tumor uptake and tumor-to-blood ratio among the tested conjugates. In conclusion, [68Ga]Ga-(HE)3-ZHER3-NODAGA remains the favorable variant for PET imaging of HER3 expression.

SUBMITTER: Rinne SS

PROVIDER: S-EPMC6881397 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Increase in negative charge of 68Ga/chelator complex reduces unspecific hepatic uptake but does not improve imaging properties of HER3-targeting affibody molecules.

Rinne Sara S SS Dahlsson Leitao Charles C Gentry Joshua J Mitran Bogdan B Abouzayed Ayman A Tolmachev Vladimir V Ståhl Stefan S Löfblom John J Orlova Anna A

Scientific reports 20191127 1

Upregulation of the human epidermal growth factor receptor type 3 (HER3) is a common mechanism to bypass HER-targeted cancer therapy. Affibody-based molecular imaging has the potential for detecting and monitoring HER3 expression during treatment. In this study, we compared the imaging properties of newly generated 68Ga-labeled anti-HER3 affibody molecules (HE)3-ZHER3-DOTA and (HE)3-ZHER3-DOTAGA with previously reported [68Ga]Ga-( ...[more]

PMID: 31776413

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Project description:Affibody molecules are small affinity-engineered scaffold proteins which can be engineered to bind to desired targets. The therapeutic potential of using an affibody molecule targeting HER2, fused to an albumin-binding domain (ABD) and conjugated with the cytotoxic maytansine derivate MC-DM1 (AffiDC), has been validated. Biodistribution studies in mice revealed an elevated hepatic uptake of the AffiDC, but histopathological examination of livers showed no major signs of toxicity. However, previous clinical experience with antibody drug conjugates have revealed a moderate- to high-grade hepatotoxicity in treated patients, which merits efforts to also minimize hepatic uptake of the AffiDCs. In this study, the aim was to reduce the hepatic uptake of AffiDCs and optimize their in vivo targeting properties. We have investigated if incorporation of hydrophilic glutamate-based spacers adjacent to MC-DM1 in the AffiDC, (ZHER2:2891)2-ABD-MC-DM1, would counteract the hydrophobic nature of MC-DM1 and, hence, reduce hepatic uptake. Two new AffiDCs including either a triglutamate-spacer-, (ZHER2:2891)2-ABD-E3-MC-DM1, or a hexaglutamate-spacer-, (ZHER2:2891)2-ABD-E6-MC-DM1 next to the site of MC-DM1 conjugation were designed. We radiolabeled the hydrophilized AffiDCs and compared them, both in vitro and in vivo, with the previously investigated (ZHER2:2891)2-ABD-MC-DM1 drug conjugate containing no glutamate spacer. All three AffiDCs demonstrated specific binding to HER2 and comparable in vitro cytotoxicity. A comparative biodistribution study of the three radiolabeled AffiDCs showed that the addition of glutamates reduced drug accumulation in the liver while preserving the tumor uptake. These results confirmed the relation between DM1 hydrophobicity and liver accumulation. We believe that the drug development approach described here may also be useful for other affinity protein-based drug conjugates to further improve their in vivo properties and facilitate their clinical translatability.

Dataset Information

Increase in negative charge of 68Ga/chelator complex reduces unspecific hepatic uptake but does not improve imaging properties of HER3-targeting affibody molecules.

Publications

Increase in negative charge of <sup>68</sup>Ga/chelator complex reduces unspecific hepatic uptake but does not improve imaging properties of HER3-targeting affibody molecules.

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