| 1. |
- Mitran, Bogdan
(författare)
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Prostate cancer theranostics using GRPR antagonist RM26
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The malignant transformation of cells is often associated with an alteration of their molecular phenotype, resulting in overexpression of several cell surface proteins. Gastrin-releasing peptide receptor (GRPR) and prostate-specific membrane antigen (PSMA) are examples of such pro-teins that are expressed at a high density in prostate cancer. GRPR is primarily expressed in earlier stages of prostate cancer and tends to decrease with disease progression. This expression pattern indicates that GRPR could be a promising target for imaging and treatment of oligometa-static prostate cancer, an early step in prostate cancer progression characterized by limited meta-static spread. In contrast, the expression of PSMA increases with cancer progression and is significantly upregulated as tumors dedifferentiate into higher grade, in androgen-insensitive and metastatic lesions.This thesis is based on five original articles (papers I-V) and focuses on the preclinical de-velopment of radiotracers for imaging and treatment of prostate cancer. The work can be divided into three distinct parts: (1) the development and optimization of GRPR-antagonist RM26 for high contrast PET and SPECT imaging of oligometastatic prostate cancer (papers I-III), (2) the preclinical evaluation of 177Lu-labeled RM26 as a potential candidate for peptide receptor radionuclide therapy (PRRT) in GRPR-expressing tumors, alone or in combination with anti-HER2 antibody trastuzumab (paper IV), and (3) the development of a bispecific heterodimer targeting both PSMA and GRPR in prostate cancer (paper V).We have demonstrated that the in vitro and in vivo properties of GRPR antagonist RM26 are strongly influenced by the choice of chelator-radionuclide complex and that long-lived radionuclides are desirable for high-contrast imaging. Furthermore, our data indicate that 55Co-NOTA-PEG2-RM26 has remarkable potential for next-day high-contrast PET imaging of GRPR-expressing tumors. Experimental PRRT using 177Lu-DOTAGA-PEG2-RM26 resulted in a pronounced inhibition of tumor growth and a significantly longer median survival. Interestingly, survival was further improved when trastuzumab was co-injected with 177Lu-DOTAGA-PEG2-RM26. These data indicate that blocking HER2 with trastuzumab decreased the repairing ability of irradiated cells. Finally, we developed a heterodimer (NOTA-DUPA-RM26) for imaging GRPR and PSMA expression in prostate cancer shortly after administration.In conclusion, we have successfully developed and preclinically evaluated radioconjugates for GRPR-directed theranostics in oligometastatic prostate cancer using the bombesin antagonistic analog RM26.
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| 2. |
- Rosestedt, Maria
(författare)
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Affibody Molecules for HER3-targeted Theranostics of Malignant Tumours
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The HER3 receptor plays a strong role in disease progression and resistance to therapies in several cancer types. Due to its endogenous expression and low overexpression in malignant tumours, it is a particularly challenging target. The primary aim of this thesis project was to develop, evaluate and characterize affibody molecules for theranostic applications in HER3-expressing malignant tumours.Paper I investigated the in vivo targeting properties and therapeutic efficacy of a bivalent affibody construct fused with an albumin binding domain, ZHER3-ABD-ZHER3. This construct could slow down the growth of HER3-expressing tumour xenografts without causing health problems or side effects in mice.Paper II compared the in vitro and in vivo properties of two HER3-targeting affibody molecules (Z08698 and Z08699) to select an imaging probe for HER3 diagnostics. While the two constructs had similar properties, Z08698 demonstrated better blood clearance and better radioactivity retention in tumours.Paper III and IV present the development of a HER3 imaging probe for PET using gallium and cobalt isotopes. We demonstrated that imaging of HER3 expression could be obtained as soon as 3 h pi using gallium-68. Additionally, we demonstrated that affibody molecules labelled with a neutral cobalt-NOTA complex had a lower radioactivity uptake in the liver than molecules radiolabelled with a positive gallium-NOTA complex. Imaging contrast increased over time. As the dose of the injected protein increased, the activity uptake in normal organs decreased, whereas the tumour uptake remained the same, which improved the imaging contrast and allowed discrimination between xenografts with high and low HER3 expression. This modification did not influence tumour activity uptake.Paper V presents the HER3-targeting affibody molecule trimer as a tool to block hepatic uptake in order to increase the imaging contrast in the liver. The trimer demonstrated its ability to bind to endogenous receptors in the liver, which decreased the hepatic uptake of the radiolabelled monomer. This phenomenon enabled the monomer to pass the liver barrier, which increased tumour radioactivity uptake and improved imaging contrast.
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| 3. |
- Garousi, Javad
(författare)
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Development of ADAPT-based tracers for radionuclide molecular imaging of cancer
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- ABD-Derived Affinity Proteins (ADAPTs) is a novel class of small engineered scaffold proteins based on albumin-binding domain (ABD) of streptococcal protein G. High affinity ADAPT binders against various therapeutic targets can be selected. In this thesis, we report a development of ADAPT-based radionuclide imaging agents providing high sensitivity and specificity of molecular imaging of HER2 expression in disseminated cancers.We investigated the feasibility of the use of ADAPTs as imaging agents and influence of molecular design and radiolabeling chemistry on in vivo targeting and biodistribution properties of the tracers.In Paper I we demonstrated the feasibility of the use of anti-HER2 ADAPT6 molecule as a high contrast imaging agent;In Paper II we evaluated the influence of composition of histidine-containing tag on in vivo biodistribution of ADAPT-based tracers labeled with 99mTc using 99mTc(CO)3 binding to histidine-containing tags and 111In using DOTA chelator at N-terminus;In Paper III we evaluated the influence of different aspects of N-terminus leading sequence on targeting including effect of sequence size on clearance rate and effect of the composition of the sequence on biodistribution profile;In Paper IV, we evaluated the influence of residualizing properties and positioning of the label on biodistribution and targeting; andIn Paper V, we compared tumor-targeting properties of the ADAPT6 labeled at C-terminus with 99mTc using N3S chelator and 111In using DOTA chelator.In conclusion, ADAPTs constitute a very promising class of targeting probes for molecular imaging providing high contrast. Molecular design of the ADAPT proteins and chelators/linkers for labeling has an appreciable effect on their imaging properties.
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| 4. |
- Strand, Joanna, 1986-
(författare)
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Affibody Molecules for PET Imaging
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Optimization of Affibody molecules would allow for high contrast imaging of cancer associated surface receptors using molecular imaging. The primary aim of the thesis was to develop Affibody-based PET imaging agents to provide the highest possible sensitivity of RTK detection in vivo. The thesis evaluates the effect of radiolabelling chemistry on biodistribution and targeting properties of Affibody molecules directed against HER2 and PDGFRβ. The thesis is based on five published papers (I-V).Paper I. The targeting properties of maleimido derivatives of DOTA and NODAGA for site-specific labelling of a recombinant HER2-binding Affibody molecule radiolabelled with 68Ga were compared in vivo. Favourable in vivo properties were seen for the Affibody molecule with the combination of 68Ga with NODAGA.Paper II. The aim was to compare the biodistribution of 68Ga- and 111In-labelled HER2-targeting Affibody molecules containing DOTA, NOTA and NODAGA at the N-terminus. This paper also demonstrated favourable in vivo properties for Affibody molecules in combination with 68Ga and NODAGA placed on the N-terminus.Paper III. The influence of chelator positioning on the synthetic anti-HER2 affibody molecule labelled with 68Ga was investigated. The chelator DOTA was conjugated either at the N-terminus, the middle of helix-3 or at the C-terminus of the Affibody molecules. The N-terminus placement provided the highest tumour uptake and tumour-to-organ ratios.Paper IV. The aim of this study was to evaluate if the 68Ga labelled PDGFRβ-targeting Affibody would provide an imaging agent suitable for PDGFRβ visualization using PET. The 68Ga labelled conjugate provided high-contrast imaging of PDGFRβ-expressing tumours in vivo using microPET as early as 2h after injection.Paper V. This paper investigated if the replacement of IHPEM with IPEM as a linker molecule for radioiodination of Affibody molecules would reduce renal retention of radioactivity. Results showed that the use of the more lipophilic linker IPEM reduced the renal radioactivity retention for radioiodinated Affibody molecules.In conclusion, this thesis clearly demonstrates that the labelling strategy is of great importance with a substantial influence on the targeting properties of Affibody molecules and should be taken under serious considerations when developing new imaging agents.
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| 5. |
- Honarvar, Hadis, 1984-
(författare)
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Development of Affibody molecules for radionuclide molecular imaging and therapy of cancer
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Affibody molecules are a promising class of scaffold-based targeting proteins for radionuclide-based imaging and therapy of cancer. This thesis work is based on 5 original research articles (papers I-V), which focus on optimization of molecular design of HER2-binding Affibody variants for high contrast imaging of this predictive biomarker as well as development of Affibody molecules suitable for radionuclide-based targeted therapies. Papers I and II were dedicated to evaluation of the influence of the macrocyclic chelator DOTA positioning at N-terminus, in the middle of helix-3 and at C terminus of a synthetic Affibody molecule, ZHER2:S1. These synthetic variants were labelled with different radionuclides i.e. 111In and 68Ga to study also the effect of different labels on their biodistribution properties.In paper III a 2-helix variant, Z342min, was developed using native ligation cyclization to cross-link helices one and two resulting in a stable 2-helix scaffold and characterized in vivo. This study was performed with the aim to obtain structure-properties relationship for development of smaller Affibody molecules. Papers IV and V were devoted to development of therapeutic strategies. In paper IV, a series of peptide based chelators was investigated for labelling of Affibody molecules with 188Re to provide low renal retention. In paper V, a pretargeting approach using peptide nucleic acid was investigated. These studies were performed with the aim to overcome the high renal retention of Affibody molecules when labelled with residualizing therapeutic radionuclides. Otherwise, the particle emitting radiometals could damage the kidneys more than the tumours.The results obtained for anti-HER2 Affibody molecules summarized in this thesis might be of importance for the development of other scaffold protein based targeting agents.
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