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  • 1.
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Engineering of Affibody molecules for Radionuclide Molecular Imaging and Intracellular Targeting2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Affibody molecules are small (7 kDa) affinity proteins of non-immunoglobulin origin that have been generated to specifically interact with a large number of clinically important molecular targets.

    In this thesis, Affibody molecules have been employed as tracers for radionuclide molecular imaging of HER2- and IGF-1R-expressing tumors, paper I-IV, and for surface knock-down of EGFR, paper V. In paper I, a tag with the amino acid sequence HEHEHE was fused to the N-terminus of a HER2-specific Affibody molecule, (ZHER2), and was shown to enable facile IMAC purification and efficient tri-carbonyl 99mTc-labeling. In vivo evaluation of radioactivity uptake in different organs showed an improved biodistribution, including a 10-fold lower radioactivity uptake in liver, compared to the same construct with a H6-tag. In paper II, it was further shown that an N-terminally placed HEHEHE-tag on ZHER2 provided lower unspecific uptake of radioactivity in liver compared to its H6-tagged counterpart even when radiolabeling was at the C-terminus using alternative chemistries to attach 99mTc, 111In or 125I. In paper III, the H6-tag’s composition and position was varied with regards to charge, hydrophobicity and its C- or N-terminal placement on ZHER2. Among the ten variants investigated, it was found that an N-terminal HEHEHE-tag provided the most favorable overall biodistribution profile and that introduction of hydrophobic and positively charged amino acids provoked liver uptake of radioactivity. In paper IV, the HEHEHE-tag was shown to enable IMAC purification and tri-carbonyl 99mTc-labeling of an IGF-1R-specific Affibody molecule and improved its overall biodistribution when compared to the same construct with a H6-tag. In paper V, the aim was to develop an intracellular receptor-entrapment system to reduce the surface levels of EGFR. An EGFR-specific Affibody molecule was expressed as a fusion to different mutants of an intracellular transport protein in SKOV-3 cells, resulting in a collection of cell lines with 50%, 60%, 80% and 96% reduced surface level of EGFR. Analysis of the proliferation rate of these cell lines showed that a modest reduction (15%) in proliferation occurs between 60% and 80% reduction of the surface level of EGFR.

  • 2.
    Hofström, Camilla
    et al.
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Altai, Mohamed
    Honarvar, H.
    Strand, J.
    Malmberg, J.
    Hosseinimehr, Seyed Jalal
    Orlova, Anna
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Tolmachev, Vladimir
    HAHAHA, HEHEHE,HIHIHI or HKHKHK: influence of position and composition of histidine containing tags on biodistribution of [99mTc(CO)3]+-labeled Affibody moleculesManuscript (preprint) (Other academic)
  • 3.
    Hofström, Camilla
    et al.
    KTH, School of Biotechnology (BIO), Protein Technology.
    Altai, Mohamed
    Honarvar, Hadis
    Strand, Joanna
    Malmberg, Jennie
    Hosseinimehr, Seyed Jalal
    Orlova, Anna
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Protein Technology.
    Tolmachev, Vladimir
    HAHAHA, HEHEHE, HIHIHI, or HKHKHK: Influence of Position and Composition of Histidine Containing Tags on Biodistribution of [Tc-99m(CO)(3)](+)-Labeled Affibody Molecules2013In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 56, no 12, 4966-4974 p.Article in journal (Refereed)
    Abstract [en]

    Engineered affibody molecules can be used for high contrast in vivo molecular imaging. Extending a recombinantly produced HER2 binding affibody molecule with a hexa-histidine tag allows for convenient purification by immobilized metal-ion affinity chromatography and labeling with [Tc-99m(CO)(3)](+) but increases radioactivity uptake in the liver. To investigate the impact of charge, lipophilicity, and position on biodistribution, 10 variants of a histidine-based tag was attached to a HER2 binding affibody molecule. The biochemical properties and the HER2 binding affinity appeared to be similar for all variants. In vivo, positive charge promoted liver uptake. For N-terminally placed tags, promoted liver uptake and decreased kidney uptake. Kidney uptake was higher for C-terminally placed tags compared to their N-terminal counterparts. The variant with the amino acid composition HEHEHE placed in the N-terminus gave the lowest nonspecific uptake.

  • 4.
    Hofström, Camilla
    et al.
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Orlova, Anna
    Altai, Mohamed
    Wångsell, Fredrik
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Tolmachev, Vladimir
    Use of a HEHEHE Purification Tag Instead of a Hexahistidine Tag Improves Biodistribution of Affibody Molecules Site-Specifically Labeled with Tc-99m, In-111 and I-1252011In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 54, no 11, 3817-3826 p.Article in journal (Refereed)
    Abstract [en]

    Affibody molecules are a class of small (similar to 7 kDa) robust scaffold proteins suitable for radionuclide molecular imaging in vivo. The attachment of a hexahistidine (His(6))-tag to the Affibody molecule allows facile purification by immobilized metal ion affinity chromatography (IMAC) but leads to high accumulation of radioactivity in the liver. Earlier, we have demonstrated that replacement of the His(6)- tag with the negatively charged histidine-glutamate-histidine-glutamate-histidine-glutamate (HEHEHE)-tag permits purification of Affibody molecules by IMAC, enables labeling with [Tc-99m(CO)(3)](+), and provides low hepatic accumulation of radioactivity. In this study, we compared the biodistribution of cysteine-containing Affibody molecules site-specifically labeled with In-111, Tc-99m, and I-125 at the C-terminus, having a His(6)-tag at the N- or C-terminus or a HEHEHE-tag at the N-terminus. We show that the use of a HEHEHE-tag provides appreciable reduction of hepatic radioactivity, especially for radiometal labels. We hope that this information can also be useful for development of other scaffold protein-based imaging agents.

  • 5.
    Hofström, Camilla
    et al.
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Stadler, C.
    Vermet, E.
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Step-wise down regulationof the epidermal growth factor receptor by affinity-based intracellular redirectionManuscript (preprint) (Other academic)
  • 6.
    Larsson, Karin
    et al.
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101).
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101).
    Lindskog, C.
    Hansson, M.
    Angelidou, P.
    Hökfelt, T.
    Uhlén, Mathias
    KTH, School of Biotechnology (BIO).
    Wernérus, H.
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101).
    Hober, Sophia
    KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101). KTH, School of Biotechnology (BIO), Proteomics (closed 20130101).
    Novel antigen design for the generation of antibodies to G-protein-coupled receptors2011In: JIM - Journal of Immunological Methods, ISSN 0022-1759, E-ISSN 1872-7905, Vol. 370, no 1-2, 14-23 p.Article in journal (Refereed)
    Abstract [en]

    Antibodies are important tools for the study of G-protein-coupled receptors, key proteins in cellular signaling. Due to their large hydrophobic membrane spanning regions and often very short loops exposed on the surface of the cells, generation of antibodies able to recognize the receptors in the endogenous environment has been difficult. Here, we describe an antigen-design method where the extracellular loops and N-terminus are combined to a single antigen for generation of antibodies specific to three selected GPCRs: NPY5R, B2ARN and GLP1R. The design strategy enabled straightforward antigen production and antibody generation. Binding of the antibodies to intact receptors was analyzed using flow cytometry and immunofluorescence based confocal microscopy on A-431 cells overexpressing the respective GPCR. The antibody-antigen interactions were characterized using epitope mapping, and the antibodies were applied in immunohistochemical staining of human tissues. Most of the antibodies showed specific binding to their respective overexpressing cell line but not to the non-transfected cells, thus indicating binding to their respective target receptor. The epitope mapping showed that sub-populations within the purified antibody pool recognized different regions of the antigen. Hence, the genetic combination of several different epitopes enables efficient generation of specific antibodies with potential use in several applications for the study of endogenous receptors.

  • 7.
    Larsson, Karin
    et al.
    KTH, School of Biotechnology (BIO), Proteomics.
    Hofström, Camilla
    KTH, School of Biotechnology (BIO).
    Lindskog, C
    Uhlén, Mattias
    KTH, School of Biotechnology (BIO), Proteomics.
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO).
    Hansson, M
    Hober, Sophia
    KTH, School of Biotechnology (BIO).
    Angelidou, Pia
    KTH, School of Biotechnology (BIO).
    Hökfelt, T
    Wernérus, Henrik
    KTH, School of Biotechnology (BIO).
    Novel antigen design for the generation of G-protein-coupled receptorantibodies.Manuscript (preprint) (Other academic)
  • 8.
    Lindberg, Hanna
    et al.
    KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101).
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101).
    Altai, Mohamed
    Honorvar, Hadis
    Wållberg, Helena
    KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101).
    Orlova, Anna
    Ståhl, Stefan
    KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101).
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101).
    Tolmachev, Vladimir
    Evaluation of a HER2-targeting affibody molecule combining an N-terminal HEHEHE-tag with a GGGC chelator for Tc-99m-labelling at the C terminus2012In: Tumor Biology, ISSN 1010-4283, E-ISSN 1423-0380, Vol. 33, no 3, 641-651 p.Article in journal (Refereed)
    Abstract [en]

    Affibody molecules are a class of small (ca.7 kDa) robust scaffold proteins with high potential as tracers for radionuclide molecular imaging in vivo. Incorporation of a cysteine-containing peptide-based chelator at the C terminus provides an opportunity for stable labelling with the radionuclide Tc-99m. The use of a GGGC chelator at the C terminus has provided the lowest renal radioactivity retention of the previously investigated peptide-based chelators. Previously, it has also been demonstrated that replacement of the His(6)-tag with the negatively charged histidine-glutamate-histidine-glutamate-histidine-glutamate (HEHEHE)-tag permits purification of affibody molecules by immobilized metal ion affinity chromatography (IMAC) and provides low hepatic accumulation of radioactivity of conjugates site-specifically labelled at the C terminus using several different nuclides. We hypothesized that the combination of a HEHEHE-tag at the N terminus and a GGGC chelator at the C terminus of an affibody molecule would be a favourable format permitting IMAC purification and providing low uptake in excretory organs. To investigate this hypothesis, a (HE)(3)-Z(HER2:342)-GGGC affibody molecule was generated. It could be efficiently purified by IMAC and stably labelled with Tc-99m. Tc-99m-(HE)(3)-Z(HER2:342)-GGGC preserved specific binding to HER2-expressing cells. In NMRI mice, hepatic uptake of Tc-99m-(HE)(3)-Z(HER2:342)-GGGC was lower than the uptake of the control affibody molecules, Tc-99m-Z(HER2:2395)-VDC and Tc-99m-Z(HER2:342)-GGGC. At 1 and 4 h after injection, the renal uptake of Tc-99m-(HE)(3)-Z(HER2:342)-GGGC was 2-3-fold lower than uptake of Tc-99m-Z(HER2:2395)-VDC, but it was substantially higher than uptake of Tc-99m-Z(HER2:342)-GGGC. Further investigation indicated that a fraction of Tc-99m was chelated by the HEHEHE-tag which caused a higher accumulation of radioactivity in the kidneys. Thus, a combination of a HEHEHE-tag and the GGGC chelator in targeting scaffold proteins was found to be undesirable in the case of Tc-99m labelling due to a partial loss of site-specificity of nuclide chelation.

  • 9. Mitran, B.
    et al.
    Altai, M.
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Protein Technology.
    Honarvar, H.
    Widstrom, C.
    Orlova, A.
    Tolmachev, V.
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Protein Technology.
    Evaluation of 99mTc-ZIGF1R: 4551-GGGC Affibody Molecule, a New Construct for Imaging the Insulin-like Growth Factor Type 1 Receptor Expression2014In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 41, S440-S440 p.Article in journal (Other academic)
  • 10. Mitran, Bogdan
    et al.
    Altai, Mohamed
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Protein Technology.
    Honarvar, Hadis
    Sandström, Mattias
    Orlova, Anna
    Tolmachev, Vladimir
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Protein Technology.
    Evaluation of Tc-99m-Z(IGF1R:4551)-GGGC affibody molecule, a new probe for imaging of insulin-like growth factor type 1 receptor expression2015In: Amino Acids, ISSN 0939-4451, E-ISSN 1438-2199, Vol. 47, no 2, 303-315 p.Article in journal (Refereed)
    Abstract [en]

    Overexpression of insulin-like growth factor-1 receptor (IGF-1R) in several cancers is associated with resistance to therapy. Radionuclide molecular imaging of IGF-1R expression in tumors may help in selecting the patients that will potentially respond to IGF-1R-targeted therapy. Affibody molecules are small (7 kDa) non-immunoglobulin-based scaffold proteins that are well-suited probes for radionuclide imaging. The aim of this study was the evaluation of an anti-IGF-1R affibody molecule labeled with technetium-99m using cysteine-containing peptide-based chelator GGGC at C-terminus. Z(IGF1R:4551)-GGGC was efficiently and stably labeled with technetium-99m (radiochemical yield 97 +/- A 3 %). Tc-99m-Z(IGF1R:4551)-GGGC demonstrated specific binding to IGF-1R-expressing DU-145 (prostate cancer) and MCF-7 (breast cancer) cell lines and slow internalization in vitro. The tumor-targeting properties were studied in BALB/c nu/nu mice bearing DU-145 and MCF-7 xenografts. [Tc-99m(CO)(3)](+)-(HE)(3)-Z(IGF1R:4551) was used for comparison. The biodistribution study demonstrated high tumor-to-blood ratios (6.2 +/- A 0.9 and 6.9 +/- A 1.0, for DU-145 and MCF-7, respectively, at 4 h after injection). Renal radioactivity concentration was 16-fold lower for Tc-99m-Z(IGF1R:4551)-GGGC than for [Tc-99m(CO)(3)](+)-(HE)(3)-Z(IGF1R:4551) at 4 h after injection. However, the liver uptake of Tc-99m-Z(IGF1R:4551)-GGGC was 1.2- to 2-fold higher in comparison with [Tc-99m(CO)(3)](+)-(HE)(3)-Z(IGF1R:4551). A possible reason for the elevated hepatic uptake of Tc-99m-Z(IGF1R:4551)-GGGC is a high lipophilicity of amino acids in the binding site of Z(IGF1R:4551), which is not compensated in Tc-99m-Z(IGF1R:4551)-GGGC. In conclusion, Tc-99m-Z(IGF1R:4551)-GGGC can visualize the IGF-1R expression in human tumor xenografts and provides low retention of radioactivity in kidneys. Further development of this imaging agent should include molecular design aimed at reducing the hepatic uptake.

  • 11. Orlova, A.
    et al.
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Malmberg, J.
    Ahlgren, S.
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Tolmachev, V.
    HEHEHE: a new chelator for [Tc-99m(CO)(3)](+)-labeling assembling His(6)-tag in protein purification2010In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 37, no Suppl. 2, S264-S265 p.Article in journal (Other academic)
  • 12. Orlova, A.
    et al.
    Malmberg, J.
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101).
    Abrahmsen, L.
    Bergman, T.
    Sjöberg, A.
    Sandström, M.
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology (closed 20130101).
    Tolmachev, V.
    Affibody molecule 111In-DOTA-ZIGF1R:4551, a new potential probe for imaging of IGF-1R expression in malignant tumours2011In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 38, S171-S171 p.Article in journal (Other academic)
  • 13. Orlova, Anna
    et al.
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Strand, Joanna
    Varasteh, Zohreh
    Sandström, Mattias
    Andersson, Karl
    Tolmachev, Vladimir
    Gräslund, Torbjörn
    [99mTc(CO)3]+-(HE)3-Z IGF1R45514551: a new Affibody conjugate for visualization of insulin-like growth factor-1 receptor expression in malignant tumours.2013In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 40, no 3, 439-449 p.Article in journal (Refereed)
    Abstract [en]

    PURPOSE: Radionuclide imaging of insulin-like growth factor type 1 receptor (IGF-1R) expression in tumours might be used for selection of patients who would benefit from IGF-1R-targeted therapy. We have previously shown the feasibility of IGF-1R imaging using the Affibody molecule (111)In-DOTA-His(6)-Z(IGF1R:4551). The use of (99m)Tc instead of (111)In should improve sensitivity and resolution of imaging, and reduce the dose burden to patients. We hypothesized that inclusion of a HEHEHE tag instead of a His(6) tag in Z(IGF1R:4551) would permit its convenient purification using IMAC, enable labelling with [(99m)Tc(CO)(3)](+), and improve its biodistribution. METHODS: Z(IGF1R:4551) was expressed with a HEHEHE tag in the N terminus. The resulting (HE)(3)-Z(IGF1R:4551) construct was labelled with [(99m)Tc(CO)(3)](+). Targeting of IGF-1R-expressing cells using [(99m)Tc(CO)(3)](+)-(HE)(3)-Z(IGF1R:4551) was evaluated in vitro and in vivo. RESULTS: (HE)(3)-Z(IGF1R:4551) was stably labelled with (99m)Tc with preserved specific binding to IGF-1R-expressing DU-145 prostate cancer cells in vitro. In mice, [(99m)Tc(CO)(3)](+)-(HE)(3)-Z(IGF1R:4551) accumulated in IGF-1R-expressing organs (pancreas, stomach, lung and salivary gland). [(99m)Tc(CO)(3)](+)-(HE)(3)-Z(IGF1R:4551) demonstrated 3.6-fold lower accumulation in the liver and spleen than (111)In-DOTA-Z(IGF1R:4551). In NMRI nu/nu mice with DU-145 prostate cancer xenografts, the tumour uptake was 1.32 ± 0.11 %ID/g and the tumour-to-blood ratio was 4.4 ± 0.3 at 8 h after injection. The xenografts were visualized using a gamma camera 6 h after injection. CONCLUSION: (99m)Tc(CO)(3)](+)-(HE)(3)-Z(IGF1R:4551) is a promising candidate for visualization of IGF-1R expression in malignant tumours.

  • 14. Tolmachev, V.
    et al.
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Protein Technology.
    Altai, M.
    Honarvar, H.
    Strand, J.
    Malmberg, J.
    Hosseinimehr, S. J.
    Orlova, A.
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Protein Technology.
    HAHAHA-, HIHIHI-. HKHKHK. HHHHHH- and HEHEHE- tags: Influence of position and composition of histidine-containing tags on biodistribution of [99mTc(CO) 3]+- labeled affibody molecules2013In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 40, S185-S185 p.Article in journal (Other academic)
  • 15. Tolmachev, V.
    et al.
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Strand, J.
    Varasteh, Z.
    Sandström, M.
    Orlova, A.
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    99mTc(CO)3-HEHEHE-ZIGF1R:4551 affibody molecule, a poteintial imaging agent for visualization of insulin-like growth factor-1 receptor in malignant tumors.2012In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 39, S300-S300 p.Article in journal (Other academic)
  • 16. Tolmachev, Vladimir
    et al.
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Malmberg, Jennie
    Ahlgren, Sara
    Hosseinimehr, Seyed Jalal
    Sandström, Mattias
    Abrahmsen, Lars
    Orlova, Anna
    Gräslund, Torbjorn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    HEHEHE-Tagged Affibody Molecule May Be Purified by IMAC, Is Conveniently Labeled with [Tc-99m(CO)(3)](+), and Shows Improved Biodistribution with Reduced Hepatic Radioactivity Accumulation2010In: Bioconjugate chemistry, ISSN 1043-1802, E-ISSN 1520-4812, Vol. 21, no 11, 2013-2022 p.Article in journal (Refereed)
    Abstract [en]

    Affibody molecules are a class of small (ca. 7 kDa) robust scaffold proteins suitable for radionuclide molecular imaging of therapeutic targets in vivo. A hexahistidine tag at the N-terminus streamlines development of new imaging probes by enabling facile purification using immobilized metal ion affinity chromatography (IMAC), as well as convenient [Tc-99m(CO)(3)](+)-labeling. However, previous studies in mice have demonstrated that Affibody molecules labeled by this method yield higher liver accumulation of radioactivity, compared to the same tracer lacking the hexahistidine tag and labeled by an alternative method. Two variants of the HER2-binding Affibody molecule Z(HER2:342) were made in an attempt to create a tagged tracer that could be purified by immobilized metal affinity chromatography, yet would not result in anomalous hepatic radioactivity accumulation following labeling with [Tc-99m(CO)(3)](+). In one construct, the hexahistidine tag was moved to the C-terminus. In the other construct, every second histidine residue in the hexahistidine tag was replaced by the more hydrophilic glutamate, resulting in a HEHEHE-tag. Both variants, denoted Z(HER2:342)-H-6 and (HE)(3)-Z(HER2:342), respectively, could be efficiently purified using IMAC and stably labeled with [Tc-99m(CO)(3)](+) and were subsequently compared with the parental H-6-Z(HER2:342) having an N-terminal hexahistidine tag. All three variants were demonstrated to specifically bind to HER2-expressing cells in vitro. The hepatic accumulation of radioactivity in a murine model was 2-fold lower with [Tc-99m(CO)(3)](+)-Z(HER2:342)-H-6 compared to [Tc-99m(CO)(3)](+)-H-6-Z(HER2:342), and more than 10-fold lower with [Tc-99m(CO)(3)](+)-(HE)(3)-Z(HER2:342). These differences translated into appreciably superior tumor-to-liver ratio for [Tc-99m(CO)(3)](+)-(HE)(3)-Z(HER2:342) compared to the alternative conjugates. This information might be useful for development of other scaffold-based molecular imaging probes.

  • 17. Tolmachev, Vladimir
    et al.
    Malmberg, Jennie
    Hofström, Camilla
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Abrahmsén, Lars
    Bergman, Thomas
    Sjöberg, Anna
    Sandström, Mattias
    Gräslund, Torbjörn
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Orlova, Anna
    Imaging of Insulinlike Growth Factor Type 1 Receptor in Prostate Cancer Xenografts Using the Affibody Molecule (111)In-DOTA-Z(IGF1R:4551)2012In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 53, no 1, 90-97 p.Article in journal (Refereed)
    Abstract [en]

    One of the pathways leading to androgen independence in prostate cancer involves upregulation of insulinlike growth factor type 1 receptor (IGF-1R). Radionuclide imaging of IGF-1R in tumors might be used for selection of patients who would most likely benefit from IGF-1R-targeted therapy. The goal of this study was to evaluate the feasibility of in vivo radionuclide imaging of IGF-1R expression in prostate cancer xenografts using a small nonimmunoglobulin-derived binding protein called an Affibody molecule. Methods: The IGF-1R-binding Z(IGF1R:4551) Affibody molecule was site-specifically conjugated with a maleimido derivative of DOTA and labeled with (111)In. The binding of radiolabeled Z(IGF1R:4551) to IGF-1R-expressing cells was evaluated in vitro and in vivo. Results: DOTA-Z(IGF1R:4551) can be stably labeled with (111)In with preserved specific binding to IGF-1R-expressing cells in vitro. In mice, (111)In-DOTAZ(IGF1R):(4551) accumulated in IGF-1R-expressing organs (pancreas, stomach, lung, and salivary gland). Receptor saturation experiments demonstrated that targeting of DU-145 prostate cancer xenografts in NMRI nu/nu mice was IGF-1R-specific. The tumor uptake was 1.1 +/- 0.3 percentage injected dose per gram, and the tumor-to-blood ratio was 3.2 +/- 0.2 at 8 h after injection. Conclusion: This study demonstrates the feasibility of in vivo targeting of IGF-1R-expressing prostate cancer xenografts using an Affibody molecule. Further development of radiolabeled Affibody molecules might provide a useful clinical tool for stratification of patients with prostate cancer for IGF-1R-targeting therapy.

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