| 1. |
- Ahlgren, Sara, 1979-
(författare)
-
Molecular Radionuclide Imaging Using Site-specifically Labelled Recombinant Affibody Molecules : Preparation and Preclinical Evaluation
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Radionuclide molecular imaging is an emerging multidisciplinary technique that is used in modern medicine to visualise diseases at cellular and molecular levels. This thesis is based on five papers (I-V) and focuses on the development of site-specific radiolabelled recombinant anti-HER2 Affibody molecules and preclinical evaluations in vitro and in vivo of the labelled conjugates. This work is part of a preclinical development of an Affibody molecule-based tracer for molecular imaging of HER2 expressing tumours. Papers I and II report the evaluation of the Affibody molecule ZHER2:2395-C, site-specifically labelled with the radiometals 111In (for SPECT) and 57Co (as a surrogate for 55Co, suitable for PET applications) using a thiol reactive DOTA derivative as a chelator. Both conjugates demonstrated very suitable biodistribution properties, enabling high contrast imaging just a few hours after injection. Papers III and IV report the development and optimization of a technique for site-specific labelling of ZHER2:2395-C with 99mTc using an N3S chelating peptide sequence. 99mTc-ZHER2:2395-C demonstrated high and specific tumour uptake and rapid clearance of non-bound tracer from the blood, resulting in high tumour-to-non-tumour ratios shortly after injection, enabling high contrast imaging. In addition, in the study described in paper IV, freeze-dried kits previously developed for 99mTc-labelling were optimised, resulting in the development of a kit in which all the reagents and protein needed for labelling of ZHER2:2395-C with 99mTc were contained in a single vial. Paper V reports the evaluation of an anti-HER2 Affibody molecule, ABY-025, with a fundamentally re-engineered scaffold. Despite the profound re-engineering, the biodistribution pattern of 111In-ABY-025 was very similar to that of two variants of the parental molecule. It seems reasonable to believe that these results will also be applicable to Affibody molecules towards other targets. Hopefully, this work will also be helpful in the development of other small proteinaceous tracers.
|
|
| 2. |
- Malmberg, Jennie
(författare)
-
Preclinical Development of Imaging Agents for HER2 Expression in Prostate Cancer Using Radiolabeled Affibody Molecules
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is focused on pre-clinical evaluation of in vivo detection of HER2-expression in prostate cancer (PCa) patients and on the possibility of using targeted molecular imaging to personalize treatment of disseminated PCa. The work is divided into three distinct parts: (1) the establishment of a preclinical model for further studies, (2) imaging of HER2 in a murine model of PCa and (3) exploration of new treatment regimes against PCa. The characterized cell line panel reflect the heterogeneity of PCa in a way that one cell line never could, and is crucial for a better understanding of different developmental stages during the progression toward androgen independence. The possibility of molecular detection of HER2 in PCa was determined in vitro using 111In-labeled CHX-A’’DTPA-trastuzumab and anti-HER2 ABY-025 affibody molecules. A novel real-time assay for radiolabeled tracer kinetics on living cells was evaluated, in an attempt to bring early developmental work a step closer to the target environment (imaging in living systems). The second part demonstrated the possibility of imaging PCa xenografts, despite the low expression levels, and that ABY-025 is better adapted for this than the therapeutic anti-HER2 antibody trastuzumab. The study also demonstrated that a residualizing radiometal-label further improves imaging contrast. A comparative study of a HER2-binding affibody molecule N-terminally conjugated to DOTA, NOTA or NODAGA highlighted the influence of the chelator on biodistribution and emphasized the importance of taking into account potential metastatic sited during tracer development. The final study used the previously established in vitro model to explore the hypothesis of using molecular imaging of HER2 to identify PCa patients that may benefit from complemental treatment.One conclusion from this thesis is that for imaging of PCa, molecular biological context and expression of the molecular target are equally important to consider. Another, that evaluation of response to treatment also need to consider the effect on the overall phenotypic profile, and consequently what this could mean for the efficacy of the treatment. The results of this thesis are in a larger perspective related to how the heterogeneity of tumors may affect the models used for diagnostics and monitoring of cancer in general.
|
|
| 3. |
- Rinne, Sara Sophie
(författare)
-
Affibody-Based Molecular Imaging and Targeted Therapy of HER3-Expressing Cancer
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The human epidermal growth factor receptor type 3 (HER3) is overexpressed in different types of cancer and is a known contributor to disease progression and resistance to cancer therapy. This thesis is based on five original articles, which aimed to improve the diagnostic and therapeutic potential of affibody-based agents for management of HER3-expressing cancers. Papers I-III focused on the development and optimization of radiolabeled affibody molecules for radionuclide molecular imaging of HER3 expression. In particular, they investigated the influence of different radiometal/chelator complexes and hydrophilicity on the biodistribution and imaging properties of the HER3-targeting affibody molecule ZHER3. Paper IV compared the optimized ZHER3-based radiotracer with antibody and antibody-fragment based radiotracers for PET imaging of HER3 expression. In Paper V, a preclinical therapy study was conducted to investigate the efficacy of different monomeric and dimeric HER3-targeting affibody constructs for treatment of HER3-expressing cancer.It was shown that by optimizing the radiometal/chelator complex and incorporation of a hydrophilic (HE)3-tag the imaging properties of ZHER3-based radiotracers could be improved (Papers I-III). Generally, replacing a positively charged radiometal/chelator complex with a neutral or negatively charged complex improved the image contrast by reducing the normal organ uptake, especially in the liver. Further, it was demonstrated that the optimized affibody-based tracer [68Ga]Ga-(HE)3-ZHER3-NODAGA could provide higher contrast PET images of HER3 expression than the 89Zr-labeled antibody seribantumab and a seribantumab-derived F(ab’)2 fragment (Paper IV). The therapy study showed that the arrangement of the molecular building blocks affected the therapeutic efficacy of ZHER3-based affibody constructs. The monomeric and dimeric ABD-conjugated affibody constructs 3A and 3A3 showed the best therapeutic efficacy among the tested constructs and were able to delay tumor growth and prolong survival with the same efficacy as the therapeutic HER3-targeting antibody seribantumab (Paper V).In conclusion, the results described in this thesis show that HER3-targeting affibody-based agents could be well-suited for molecular imaging of HER3 expression and HER3-targeted therapy in cancer. Careful optimization of the molecular design could improve the imaging properties and therapeutic efficacy of HER3-targeting affibody molecules. Most importantly, it was demonstrated that HER3-targeting affibody molecules could provide superior diagnostic images and similar therapeutic effect than more traditional approaches for management of HER3-expressing cancer.
|
|
| 4. |
- Sundberg, Åsa Liljegren, 1974-
(författare)
-
Tumour Targeting Using Radiolabelled EGF Conjugates : Preclinical Studies
- 2004
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tumour targeted radiotherapy is an appealing approach for treatment of disseminated tumour cells. A targeting agent that specifically binds to a structure on tumour cells is then used to transport therapeutically relevant radionuclides. The epidermal growth factor receptor, EGFR, is overexpressed on tumour cells in several malignancies, e.g. highly malignant gliomas. In this thesis, three types of radiolabelled EGF-conjugates, aimed for targeting to EGFR-expressing tumour cells, were developed and studied: EGF-dextran labelled with 125I, EGF labelled with 211At, and two EGF-chelates, DTPA-EGF and Bz-DTPA-EGF, labelled with the radioactive metals 111In and 177Lu. The targeting properties of radioiodinated EGF-dextran were first studied in cultured glioma cells. Radioiodine coupled to the dextran part of EGF-dextran was retained in cells appreciably longer than radioiodine coupled to EGF. This can give about 100 times increased radiation dose to tumour cells.Targeting with 211At-EGF was investigated in combination with the tyrosine kinase inhibitor gefitinib (Iressa™, ZD1839). The uptake of 211At-EGF in EGFR-expressing tumour cells increased with increasing gefitinib concentrations. This was the case for both gefitinib-resistant and gefitinib-sensitive cell lines. The effect of the combined treatment on cell survival, however, differed between the cell lines in an unexpected way. In gefitinib resistant cells, combined treatment decreased cell survival approximately 3.5 times relative to 211At-EGF treatment alone. In gefitinib sensitive cells, however, combined treatment increased the cell survival (i.e. a protective effect).The EGF-chelates studied ([111In]DTPA-EGF, [111In]Bz-DTPA-EGF and [177Lu]Bz-DTPA-EGF) all bound specifically with high affinity (Kd≈2 nM) to EGFR on cultured glioma cells. They were internalised after binding, and the cellular retention of radionuclides was high (60% remained after 45 h). A biodistribution study in mice showed that liver and kidneys accumulated a majority of the radioactivity. The EGF-chelates bound EGFR specifically also in vivo. A tumour-to-blood ratio of 25 was achieved in a preliminary study.
|
|
