| 1. |
- Lindberg, Hanna, et al.
(author)
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A truncated and dimeric format of an Affibody library on bacteria enables FACS-mediated isolation of amyloid-beta aggregation inhibitors with subnanomolar affinity
- 2015
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In: Biotechnology Journal. - : Wiley. - 1860-6768 .- 1860-7314. ; 10:11, s. 1707-1718
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Journal article (peer-reviewed)abstract
- The amyloid hypothesis suggests that accumulation of amyloid β (Aβ) peptides in the brain is involved in development of Alzheimer's disease. We previously generated a small dimeric affinity protein that inhibited Aβ aggregation by sequestering the aggregation prone parts of the peptide. The affinity protein is originally based on the Affibody scaffold, but is evolved to a distinct interaction mechanism involving complex structural rearrangement in both the Aβ peptide and the affinity proteins upon binding. The aim of this study was to decrease the size of the dimeric affinity protein and significantly improve its affinity for the Aβ peptide to increase its potential as a future therapeutic agent. We combined a rational design approach with combinatorial protein engineering to generate two different affinity maturation libraries. The libraries were displayed on staphylococcal cells and high-affinity Aβ-binding molecules were isolated using flow-cytometric sorting. The best performing candidate binds Aβ with a KD value of around 300 pM, corresponding to a 50-fold improvement in affinity relative to the first-generation binder. The new dimeric Affibody molecule was shown to capture Aβ1-42 peptides from spiked E. coli lysate. Altogether, our results demonstrate successful engineering of this complex binder for increased affinity to the Aβ peptide.
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| 2. |
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| 3. |
- Dahlsson Leitao, Charles
(author)
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Affibody-mediated targeting of HER-family receptors for cancer imaging and therapy
- 2022
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Doctoral thesis (other academic/artistic)abstract
- Proteins are remarkable molecules with diverse and specialized functions playing essential roles in most biological processes. One such function is protecting us from diseases by the action of antibodies in our immune system that can recognize and mediate the destruction of invading pathogens by binding to foreign epitopes found on non-self proteins. The concept of utilizing specific protein-protein interactions to achieve a therapeutic effect has for several decades been a cornerstone for the development of cancer-directed treatments. While antibodies have formed a basis for the development of such drugs, other protein alternatives may be engineered to complement current antibody-based treatments, and may even prove to possess superior features. This thesis focuses on the engineering of affibody molecules, a small alternative scaffold protein, for design and development of novel cancer-targeting therapeutic and diagnostic drugs. There are many different strategies that have been investigated for inhibiting cancer progression and tumour growth with perhaps one of the most straightforward involving disruption of dysregulated growth-promoting signalling pathways. Members of the human epidermal growth factor receptor (HER) family is prominently expressed in various cancer types and have been shown to be intricately involved in tumorigenesis. One of the members (HER3) often becomes upregulated in cancer and have been shown to mediate acquired resistance to targeted therapies by the mechanism of ligand-induced activation. We have designed five novel affibody-based HER3-targeting molecules able to prevent ligand-binding and consequently activation of HER3. We investigated the targeting properties and biodistribution profiles of these molecules in vivo and subsequently evaluated the anti-tumour efficacy for the most promising variants in direct comparison to a HER3-targeting antibody with a similar inhibitory mechanism. We observed a large influence of design on both the biodistribution properties and the in vivo efficacy of different affibody molecules. Moreover, we demonstrated that two of the affibody-formats were equally effective as the antibody in inhibiting tumour growth and prolonging survival of mice bearing HER3-positive xenografts. The effectiveness of cancer treatments depends on efficient diagnostic approaches that can reliably stratify patients based on these targetable biomarkers, which is possible using radionuclide molecular imaging. We have performed a direct comparison of the diagnostic potential for visualizing HER3-expressing tumours of affibody- and antibody-based imaging probes. We concluded that affibody molecules provide superior imaging quality with higher diagnostic potential and enable early visualization of HER3-expression in tumours. Another member of the HER family that is of interest for cancer therapy is HER1 (or EGFR) but due to substantial expression in healthy tissues, targeted therapies may lead to severe side-effects. One possible solution to this is taking advantage of the distinct milieu of the tumour microenvironment to design EGFR-targeting drugs that become conditionally activated at the tumour site, but not in normal tissues, with the aim of drastically reducing systemic toxicity. We have generated an affibody molecule with anti-idiotypic binding specificity for a previously generated EGFR-binding affibody molecule, which we used to construct an affibody-based prodrug. We were able to show that, in a proof-of-concept format, this anti-idiotypic masking domain was able to block the binding to EGFR until removed by protease-mediated cleavage. We subsequently developed and characterized a more refined version of this prodrug, which we call a pro-affibody, and could show that activation by cancer-associated proteases confers binding to EGFR-expressing cancer cells and enables conditional cytotoxic payload delivery in vitro. The pro-affibody was further evaluated in vivo using tumour-bearing mice to investigate the feasibility for masked uptake in healthy tissues while retaining binding-activity in tumours. We observed a substantial reduction in EGFR-specific liver uptake compared to a control construct without a masking domain, and a strong indication of protease-mediated EGFR-binding in tumours. In conclusion, the experimental work presented in this thesis provides a rationale for designing effective affibody-based cancer therapeutics and diagnostics with different targeting strategies and demonstrates the potential of such drugs from preclinical in vivo data.
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| 4. |
- Dahlsson Leitao, Charles, et al.
(author)
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Molecular Design of HER3-Targeting Affibody Molecules : Influence of Chelator and Presence of HEHEHE-Tag on Biodistribution of 68Ga-Labeled Tracers
- 2019
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In: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 20:5
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Journal article (peer-reviewed)abstract
- Affibody-based imaging of HER3 is a promising approach for patient stratification. We investigated the influence of a hydrophilic HEHEHE-tag ((HE)3-tag) and two different gallium-68/chelator-complexes on the biodistribution of Z08698 with the aim to improve the tracer for PET imaging. Affibody molecules (HE)3-Z08698-X and Z08698-X (X = NOTA, NODAGA) were produced and labeled with gallium-68. Binding specificity and cellular processing were studied in HER3-expressing human cancer cell lines BxPC-3 and DU145. Biodistribution was studied 3 h p.i. in Balb/c nu/nu mice bearing BxPC-3 xenografts. Mice were imaged 3 h p.i. using microPET/CT. Conjugates were stably labeled with gallium-68 and bound specifically to HER3 in vitro and in vivo. Association to cells was rapid but internalization was slow. Uptake in tissues, including tumors, was lower for (HE)3-Z08698-X than for non-tagged variants. The neutral [68Ga]Ga-NODAGA complex reduced the hepatic uptake of Z08698 compared to positively charged [68Ga]Ga-NOTA-conjugated variants. The influence of the chelator was more pronounced in variants without (HE)3-tag. In conclusion, hydrophilic (HE)3-tag and neutral charge of the [68Ga]Ga-NODAGA complex promoted blood clearance and lowered hepatic uptake of Z08698. [68Ga]Ga-(HE)3-Z08698-NODAGA was considered most promising, providing the lowest blood and hepatic uptake and the best imaging contrast among the tested variants.
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| 5. |
- Oroujeni, Maryam, PhD, 1982-, et al.
(author)
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Preclinical Evaluation of [Ga-68]Ga-DFO-ZEGFR:2377 : A Promising Affibody-Based Probe for Noninvasive PET Imaging of EGFR Expression in Tumors
- 2018
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In: Cells. - : MDPI. - 2073-4409. ; 7:9
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Journal article (peer-reviewed)abstract
- Radionuclide imaging of epidermal growth factor receptor (EGFR) expression in tumors may stratify patients for EGFR-targeting therapies and predict response or resistance to certain treatments. Affibody molecules, which are nonimmunoglobulin scaffold proteins, have a high potential as probes for molecular imaging. In this study, maleimido derivative of desferrioxamine B (DFO) chelator was site-specifically coupled to the C-terminal cysteine of the anti-EGFR affibody molecule ZEGFR:2377, and the DFO-ZEGFR:2377 conjugate was labeled with the generator-produced positron-emitting radionuclide Ga-68. Stability, specificity of binding to EGFR-expressing cells, and processing of [Ga-68]Ga-DFO-ZEGFR:2377 by cancer cells after binding were evaluated in vitro. In vivo studies were performed in nude mice bearing human EGFR-expressing A431 epidermoid cancer xenografts. The biodistribution of [Ga-68]Ga-DFO-ZEGFR:2377 was directly compared with the biodistribution of [Zr-89]Zr-DFO-ZEGFR:2377. DFO-ZEGFR:2377 was efficiently (isolated yield of 73 +/- 3%) and stably labeled with Ga-68. Binding of [Ga-68]Ga-DFO-ZEGFR:2377 to EGFR-expressing cells in vitro was receptor-specific and proportional to the EGFR expression level. In vivo saturation experiment demonstrated EGFR-specific accumulation of [Ga-68]Ga-DFO-ZEGFR:2377 in A431 xenografts. Compared to [Zr-89]Zr-DFO-ZEGFR:2377, [Ga-68]Ga-DFO-ZEGFR:2377 demonstrated significantly (p < 0.05) higher uptake in tumors and lower uptake in spleen and bones. This resulted in significantly higher tumor-to-organ ratios for [Ga-68]Ga-DFO-ZEGFR:2377. In conclusion, [Ga-68]Ga-DFO-ZEGFR:2377 is a promising probe for imaging of EGFR expression.
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| 6. |
- Persson, Jonas, et al.
(author)
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Discovery, optimization and biodistribution of an Affibody molecule for imaging of CD69
- 2021
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In: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
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Journal article (peer-reviewed)abstract
- Due to the wide scale of inflammatory processes in different types of disease, more sensitive and specific biomarkers are required to improve prevention and treatment. Cluster of differentiation 69 (CD69) is one of the earliest cell surface proteins expressed by activated leukocytes. Here we characterize and optimize potential new imaging probes, Affibody molecules targeting CD69 for imaging of activated immune cells. Analysis of candidates isolated in a previously performed selection from a Z variant E. coli library to the recombinant extracellular domain of human CD69, identified one cross-reactive Z variant with affinity to murine and human CD69. Affinity maturation was performed by randomization of the primary Z variant, followed by selections from the library. The resulting Z variants were evaluated for affinity towards human and murine CD69 and thermal stability. The in vivo biodistribution was assessed by SPECT/CT in rats following conjugation of the Z variants by a DOTA chelator and radiolabeling with Indium-111. A primary Z variant with a K-d of approximately 50 nM affinity to human and murine CD69 was identified. Affinity maturation generated 5 additional Z variants with improved or similar affinity. All clones exhibited suitable stability. Radiolabeling and in vivo biodistribution in rat demonstrated rapid renal clearance for all variants, while the background uptake and washout varied. The variant Z(CD69:4) had the highest affinity for human and murine CD69 (34 nM) as well as the lowest in vivo background binding. In summary, we describe the discovery, optimization and evaluation of novel Affibody molecules with affinity for CD69. Affibody molecule Z(CD69:4) is suitable for further development for imaging of activated immune cells.
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| 7. |
- Rinne, Sara S., et al.
(author)
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Increase in negative charge of Ga-68/chelator complex reduces unspecific hepatic uptake but does not improve imaging properties of HER3-targeting affibody molecules
- 2019
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In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 9
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Journal article (peer-reviewed)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 Ga-68-labeled anti-HER3 affibody molecules (HE)(3)-Z(HER3)-DOTA and (HE)(3)-Z(HER3)-DOTAGA with previously reported [Ga-68]Ga-(HE)(3)-Z(HER3)-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)-Z(HER3)-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 [Ga-68]Ga-(HE)(3)-Z(HER3)-NODAGA. Presence of the negatively charged Ga-68-DOTAGA complex reduced the unspecific hepatic uptake, but did not improve overall biodistribution of the conjugate. [Ga-68]Ga-(HE)(3)-Z(HER3)-DOTAGA and [Ga-68]Ga-(HE)(3)-Z(HER3)-NODAGA had similar tumor-to-liver ratios, but [Ga-68]Ga-(HE)(3)-Z(HER3)-NODAGA had the highest tumor uptake and tumor-to-blood ratio among the tested conjugates. In conclusion, [Ga-68] Ga-(HE)(3)-Z(HER3)-NODAGA remains the favorable variant for PET imaging of HER3 expression.
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| 8. |
- Rinne, Sara S., et al.
(author)
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Influence of Residualizing Properties of the Radiolabel on Radionuclide Molecular Imaging of HER3 Using Affibody Molecules
- 2020
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In: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 21:4
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Journal article (peer-reviewed)abstract
- Human epidermal growth factor receptor type 3 (HER3) is an emerging therapeutic target in several malignancies. To select potential responders to HER3-targeted therapy, radionuclide molecular imaging of HER3 expression using affibody molecules could be performed. Due to physiological expression of HER3 in normal organs, high imaging contrast remains challenging. Due to slow internalization of affibody molecules by cancer cells, we hypothesized that labeling (HE)(3)-Z(HER3:08698)-DOTAGA affibody molecule with non-residualizing [I-125]-N-succinimidyl-4-iodobenzoate (PIB) label would improve the tumor-to-normal organs ratios compared to previously reported residualizing radiometal labels. The [I-125]I-PIB-(HE)(3)-Z(HER3:08698)-DOTAGA was compared side-by-side with [In-111]In-(HE)(3)-Z(HER3:08698)-DOTAGA. Both conjugates demonstrated specific high-affinity binding to HER3-expressing BxPC-3 and DU145 cancer cells. Biodistribution in mice bearing BxPC-3 xenografts at 4 and 24h pi showed faster clearance of the [I-125]I-PIB label compared to the indium-111 label from most tissues, except blood. This resulted in higher tumor-to-organ ratios in HER3-expressing organs for [I-125]I-PIB-(HE)(3)-Z(HER3:08698)-DOTAGA at 4 h, providing the tumor-to-liver ratio of 2.4 +/- 0.3. The tumor uptake of both conjugates was specific, however, it was lower for the [I-125]I-PIB label. In conclusion, the use of non-residualizing [I-125]I-PIB label for HER3-targeting affibody molecule provided higher tumor-to-liver ratio than the indium-111 label, however, further improvement in tumor uptake and retention is needed.
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| 9. |
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| 10. |
- Malm, Magdalena, et al.
(author)
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Targeting HER3 using mono- and bispecific antibodies or alternative scaffolds
- 2016
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In: mAbs. - : Taylor & Francis. - 1942-0862 .- 1942-0870. ; 8:7, s. 1195-1209
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Journal article (peer-reviewed)abstract
- The human epidermal growth factor receptor 3 (HER3) has in recent years been recognized as a key node in the complex signaling network of many different cancers. It is implicated in de novo and acquired resistance against therapies targeting other growth factor receptors, e.g., EGFR, HER2, and it is a major activator of the PI3K/Akt signaling pathway. Consequently, HER3 has attracted substantial attention, and is today a key target for drugs in clinical development. Sophisticated protein engineering approaches have enabled the generation of a range of different affinity proteins targeting this receptor, including antibodies and alternative scaffolds that are either mono- or bispecific. Here, we describe HER3 and its role as a key tumor target, and give a comprehensive review of HER3-targeted proteins currently in development, including discussions on the opportunities and challenges of targeting this receptor.
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