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Altai, M., Garousi, J., Rinne, S. S., Schulga, A., Deyev, S. & Vorobyeva, A. (2020). On the prevention of kidney uptake of radiolabeled DARPins. EJNMMI Research, 10, Article ID 7.
Open this publication in new window or tab >>On the prevention of kidney uptake of radiolabeled DARPins
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2020 (English)In: EJNMMI Research, ISSN 2191-219X, E-ISSN 2191-219X, Vol. 10, article id 7Article in journal (Refereed) Published
Abstract [en]

Background: Designed ankyrin repeat proteins (DARPins) are small engineered scaffold proteins (14-18 kDa) that demonstrated promising tumor-targeting properties in preclinical studies. However, high renal accumulation of activity for DARPins labeled with residualizing labels is a limitation for targeted radionuclide therapy. A better understanding of the mechanisms behind the kidney uptake of DARPins could aid the development of strategies to reduce it. In this study, we have investigated whether the renal uptake of [Tc-99m]Tc(CO)(3)-G3 DARPin could be reduced by administration of compounds that act on various parts of the reabsorption system in the kidney.

Results: Co-injection of lysine or Gelofusine was not effective for the reduction of kidney uptake of [Tc-99m]Tc(CO)(3)-G3. Administration of sodium maleate before the injection of [Tc-99m]Tc(CO)(3)-G3 reduced the kidney-associated activity by 60.4 +/- 10.3%, while administration of fructose reduced it by 46.9 +/- 7.6% compared with the control. The decrease in the kidney uptake provided by sodium maleate was also observed for [Tc-99m]Tc(CO)(3)-9_29 DARPin. Preinjection of colchicine, probenecid, mannitol, or furosemide had no effect on the kidney uptake of [Tc-99m]Tc(CO)(3)-G3. Kidney autoradiography showed mainly cortical accumulation of activity for all studied groups.

Conclusion: Common clinical strategies were not effective for the reduction of kidney uptake of [Tc-99m]Tc(CO)(3)-G3. Both fructose and maleate lower the cellular ATP level in the proximal tubule cells and their reduction of the kidney reuptake indicates the involvement of an ATP-driven uptake mechanism. The decrease provided by maleate for both G3 and 9_29 DARPins indicates that their uptake proceeds through a mechanism independent of DARPin structure and binding site composition.

Place, publisher, year, edition, pages
SPRINGEROPEN, 2020
Keywords
DARPin, Radiolabel, Kidney, Reabsorption, Renal uptake
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-407141 (URN)10.1186/s13550-020-0599-1 (DOI)000511990100001 ()32020413 (PubMedID)
Funder
Swedish Society for Medical Research (SSMF)
Available from: 2020-03-19 Created: 2020-03-19 Last updated: 2020-03-19Bibliographically approved
Mitran, B., Andersson, K. G., Lindström, E., Garousi, J., Rosestedt, M., Tolmachev, V., . . . Löfblom, J. (2019). Affibody-mediated imaging of EGFR expression in prostate cancer using radiocobalt-labeled DOTA-Z(EGFR:2377). Oncology Reports, 41(1), 534-542
Open this publication in new window or tab >>Affibody-mediated imaging of EGFR expression in prostate cancer using radiocobalt-labeled DOTA-Z(EGFR:2377)
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2019 (English)In: Oncology Reports, ISSN 1021-335X, E-ISSN 1791-2431, Vol. 41, no 1, p. 534-542Article in journal (Refereed) Published
Abstract [en]

The epidermal growth factor receptor (EGFR) is often overexpressed during prostate cancer (PCa) progression towards androgen-independence after hormone therapy, but the overexpression is lower than in other types of cancers. Despite the low expression, EGFR has emerged as a promising therapeutic target for patients with castration-resistant PCa. Non-invasive methods for determination of EGFR expression in PCa can serve for patient stratification and therapy response monitoring. Radionuclide imaging probes based on affibody molecules (7 kDa) provide high contrast imaging of cancer-associated molecular targets. We hypothesized that the anti-EGFR affibody molecule DOTA-Z(EGFR:2377) labeled with Co-55 (positron-emitter, T1/2=17.5 h) would enable imaging of EGFR expression in PCa xenografts. The human PCa cell line DU-145 was used for in vitro and in vivo experiments and Co-57 was used as a surrogate for Co-55 in the present study. Binding of Co-57-DOTA-Z(EGFR:2377) to EGFR-expressing xenografts was saturable with anti-EGFR monoclonal antibody cetuximab, which would motivate the use of this tracer for monitoring the receptor occupancy during treatment. A significant dose-dependent difference in radioactivity accumulation in tumors and normal organs was observed when the biodistribution was studied 3 h after the injection of 10 and 35 mu g of Co-57-DOTA-Z(EGFR:2377): At lower doses the tumor uptake was 2-fold higher although tumor-to-organ ratios were not altered. For clinically relevant organs for PCa, tumor-to-organ ratios increased with time, and at 24 h pi were 2.2 +/- 0.5 for colon, 7 +/- 2 for muscle, and 4.0 +/- 0.7 for bones. Small animal SPECT/CT images confirmed the capacity of radiocobalt labeled DOTA-Z(EGFR:2377) to visualize EGFR expression in PCa. In conclusion, the present study demonstrated the feasibility of using the radiocobalt labeled anti-EGFR affibody conjugate Z(EGFR:2377) as an imaging agent for in vivo visualization of low EGFR-expressing tumors, like PCa, and for monitoring of receptor occupancy during cetuximab therapy as well as the importance of optimal dosing in order to achieve higher sensitivity molecular imaging.

Keywords
prostate cancer, molecular imaging, cobalt, affibody molecule, HER1, EGFR
National Category
Cancer and Oncology Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-372751 (URN)10.3892/or.2018.6792 (DOI)000452152300051 ()30320363 (PubMedID)
Funder
Swedish Research Council, 621-2012-5236Swedish Research Council, 2015-02509Swedish Research Council, 2015-02353VINNOVA, 2016-04060VINNOVA, 2017-02015Knut and Alice Wallenberg Foundation
Available from: 2019-01-15 Created: 2019-01-15 Last updated: 2019-01-15Bibliographically approved
Huizing, F. J., Garousi, J., Lok, J., Franssen, G., Hoeben, B. A. W., Frejd, F. Y., . . . Heskamp, S. (2019). CAIX-targeting radiotracers for hypoxia imaging in head and neck cancer models. Scientific Reports, 9, Article ID 18898.
Open this publication in new window or tab >>CAIX-targeting radiotracers for hypoxia imaging in head and neck cancer models
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 18898Article in journal (Refereed) Published
Abstract [en]

Hypoxia-induced carbonic anhydrase IX (CAIX) expression is a prognostic marker in solid tumors. In recent years many radiotracers have been developed, but a fair comparison of these compounds is not possible because of the diversity in tumor models and other experimental parameters. In this study we performed a direct in vivo comparison of three promising CAIX targeting radiotracers in xenografted head and neck cancer models. The biodistribution of [In-111]In-DOTA-ZCAIX:2 was directly compared with [In-111]In-DTPA-G250-F(ab')(2) and [In-111] In-DTPA-G250 in female BALB/C nu/nu mice bearing two HNSCC xenografts with different levels of CAIX expression. In vivo biodistribution was quantified by means of microSPECT/CT scans and ex vivo biodistribution was determined with the use of gamma-counter. Tumors were snap frozen and sections were stained for CAIX expression, vessels, hypoxia (pimonidazole) and tumor blood perfusion. Tracer uptake was significantly higher in SSCNij153 tumors compared to SCCNij185 tumors for [In-111]In-DOTA-HE3-ZCAIX:2: 0.32 +/- 0.03 versus 0.18 +/- 0.01%ID/g,(p = 0.003) 4 h p.i., for [In-111]In-DTPA-girentuximab-F(ab')(2): 3.0 +/- 0.5%ID/g and 1.2 +/- 0.1%ID/g (p = 0.03), 24 h p.i. and for [In-111]In-DTPA-girentuximab: 30 +/- 2.1%ID/g and 7.0 +/- 1.0%ID/g (p = 0.0002) 72 h p.i. SPECT imaging with both [In-111]In-DTPA-girentuximab-F(ab') 2 and [111In]In-DTPA-girentuximab showed a clear difference in tracer distribution between the two tumor models. The whole IgG, i.e. [In-111]In-DTPA-girentuximab, showed the highest tumor-to-muscle ratio. We showed that different CAIX-targeting radiotracers can discriminate a low CAIX-expressing tumor from a high CAIX-expressing head and neck cancer xenografts model. In these hypoxic head and neck xenograft models [In-111]In-DTPA-girentuximab showed the most promising results.

National Category
Radiology, Nuclear Medicine and Medical Imaging Cancer and Oncology
Identifiers
urn:nbn:se:uu:diva-400759 (URN)10.1038/s41598-019-54824-5 (DOI)000502605300001 ()31827111 (PubMedID)
Available from: 2020-01-03 Created: 2020-01-03 Last updated: 2020-01-03Bibliographically approved
Garousi, J., Huizing, F. J., Vorobyeva, A., Mitran, B., Andersson, K. G., Leitao, C. D., . . . Tolmachev, V. (2019). Comparative evaluation of affibody- and antibody fragments-based CAIX imaging probes in mice bearing renal cell carcinoma xenografts. Scientific Reports, 9, Article ID 14907.
Open this publication in new window or tab >>Comparative evaluation of affibody- and antibody fragments-based CAIX imaging probes in mice bearing renal cell carcinoma xenografts
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 14907Article in journal (Refereed) Published
Abstract [en]

Carbonic anhydrase IX (CAIX) is a cancer-associated molecular target for several classes of therapeutics. CAIX is overexpressed in a large fraction of renal cell carcinomas (RCC). Radionuclide molecular imaging of CAIX-expression might offer a non-invasive methodology for stratification of patients with disseminated RCC for CAIX-targeting therapeutics. Radiolabeled monoclonal antibodies and their fragments are actively investigated for imaging of CAIX expression. Promising alternatives are small non-immunoglobulin scaffold proteins, such as affibody molecules. A CAIX-targeting affibody ZCAIX:2 was re-designed with the aim to decrease off-target interactions and increase imaging contrast. The new tracer, DOTA-HE3-ZCAIX:2, was labeled with In-111 and characterized in vitro. Tumor-targeting properties of [In-111]In-DOTA-HE3-ZCAIX:2 were compared head-to-head with properties of the parental variant, [(99)mTc]Tc(CO)(3)-HE3-ZCAIX:2, and the most promising antibody fragment-based tracer, [In-111]In-DTPA-G250(Fab')(2), in the same batch of nude mice bearing CAIX-expressing RCC xenografts. Compared to the (99)mTc-labeled parental variant, [In-111]In-DOTA-HE3-ZCAIX:2 provides significantly higher tumor-to-lung, tumor-to-bone and tumor-to-liver ratios, which is essential for imaging of CAIX expression in the major metastatic sites of RCC. [In-111]In-DOTA-HE3-ZCAIX:2 offers significantly higher tumor-to-organ ratios compared with [In-111]In-G250(Fab']2. In conclusion, [In-111]In-DOTA-HE3-ZCAIX:2 can be considered as a highly promising tracer for imaging of CAIX expression in RCC metastases based on our results and literature data.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Cancer and Oncology
Identifiers
urn:nbn:se:uu:diva-396709 (URN)10.1038/s41598-019-51445-w (DOI)000490702200022 ()31624303 (PubMedID)
Funder
Swedish Cancer Society, CAN 2018/436Swedish Cancer Society, 2017/425Swedish Research Council, 2015-02353Swedish Research Council, 2015-02509
Available from: 2019-11-08 Created: 2019-11-08 Last updated: 2019-11-08Bibliographically approved
Garousi, J., Lindbo, S., Borin, J., von Witting, E., Vorobyeva, A., Oroujeni, M., . . . Hober, S. (2019). Comparative evaluation of dimeric and monomeric forms of ADAPT scaffold protein for targeting of HER2-expressing tumours. European journal of pharmaceutics and biopharmaceutics, 134, 37-48
Open this publication in new window or tab >>Comparative evaluation of dimeric and monomeric forms of ADAPT scaffold protein for targeting of HER2-expressing tumours
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2019 (English)In: European journal of pharmaceutics and biopharmaceutics, ISSN 0939-6411, E-ISSN 1873-3441, Vol. 134, p. 37-48Article in journal (Refereed) Published
Abstract [en]

ADAPTs are small engineered non-immunoglobulin scaffold proteins, which have demonstrated very promising features as vectors for radionuclide tumour targeting. Radionuclide imaging of human epidermal growth factor 2 (HER2) expression in vivo might be used for stratification of patients for HER2-targeting therapies. ADAPT6, which specifically binds to HER2, has earlier been shown to have very promising features for in vivo targeting of HER2 expressing tumours. In this study we tested the hypothesis that dimerization of ADAPT6 would increase the apparent affinity to HER2 and accordingly improve tumour targeting. To find an optimal molecular design of dimers, a series of ADAPT dimers with different linkers, -SSSG- (DiADAPT6L1), -(SSSG)(2)- (DiADAPT6L2), and -(SSSG)(3)- (DiADAPT6L3) was evaluated. Dimers in combination with optimal linker lengths demonstrated increased apparent affinity to HER2. The best variants, DiADAPT6L2 and DiADAPT6L3 were site-specifically labelled with In-111 and I-125, and compared with a monomeric ADAPT6 in mice bearing HER2-expressing tumours. Despite higher affinity, both dimers had lower tumour uptake and lower tumour-to-organ ratios compared to the monomer. We conclude that improved affinity of a dimeric form of ADAPT does not compensate the disadvantage of increased size. Therefore, increase of affinity should be obtained by affinity maturation and not by dimerization.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2019
Keywords
ADAPT, HER2, Dimer, Radionuclide molecular imaging, Indium-111, Iodine-125
National Category
Cancer and Oncology
Identifiers
urn:nbn:se:uu:diva-376893 (URN)10.1016/j.ejpb.2018.11.004 (DOI)000456225000004 ()30408518 (PubMedID)
Funder
Swedish Research Council, 2015-02353Swedish Research Council, 2015-02509VINNOVA, 2015-02509Swedish Cancer Society, CAN 2015/350Swedish Cancer Society, 2017/425
Available from: 2019-02-13 Created: 2019-02-13 Last updated: 2019-02-13Bibliographically approved
Deyev, S., Vorobyeva, A., Schulga, A., Proshkina, G., Guler, R., Lofblom, J., . . . Tolmachev, V. (2019). Comparative Evaluation of Two DARPin Variants: Effect of Affinity, Size, and Label on Tumor Targeting Properties. Molecular Pharmaceutics, 16(3), 995-1008
Open this publication in new window or tab >>Comparative Evaluation of Two DARPin Variants: Effect of Affinity, Size, and Label on Tumor Targeting Properties
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2019 (English)In: Molecular Pharmaceutics, ISSN 1543-8384, E-ISSN 1543-8392, Vol. 16, no 3, p. 995-1008Article in journal (Refereed) Published
Abstract [en]

Designed ankyrin repeat proteins (DARPins) are small engineered scaffold proteins that can be selected for binding to desirable molecular targets. High affinity and small size of DARPins render them promising probes for radionuclide molecular imaging. However, detailed knowledge on many factors influencing their imaging properties is still lacking. We have evaluated two human epidermal growth factor 2 (HER2)-specific DARPins with different size and binding properties. DARPins 9_29-H-6 and G3-H-6 were radiolabeled with iodine-125 and tricarbonyl technetium-99m and evaluated in vitro. A side-by-side comparison of biodistribution and tumor targeting was performed. HER2-specific tumor accumulation of G3-H-6 was demonstrated. A combination of smaller size and higher affinity resulted in a higher tumor uptake of G3-H-6 in comparison to 9_29-H6. Technetium-99m labeled G3-H-6 demonstrated a better biodistribution profile than 9_29-H-6, with several-fold lower uptake in liver. Radioiodinated G3-H-6 showed the best tumor-to-organ ratios. The combined effect of affinity, molecular weight, scaffold composition, and nonresidualizing properties of iodine label provided radioiodinated G3-H-6 with high clinical potential for imaging of HER2.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
DARPin, targeting, radionuclide, imaging, I-12S, Tc-99m
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-380491 (URN)10.1021/acs.molpharmaceut.8b00922 (DOI)000460600400008 ()30608701 (PubMedID)
Funder
Swedish Research Council, 2015-02353Swedish Research Council, 2015-02509Vinnova, 2016-04060Swedish Cancer Society, CAN 2015/350Swedish Cancer Society, 2017/425Swedish Society for Medical Research (SSMF)
Available from: 2019-03-28 Created: 2019-03-28 Last updated: 2019-03-28Bibliographically approved
Vorobyeva, A., Schulga, A., Konovalova, E., Güler, R., Mitran, B., Garousi, J., . . . Tolmachev, V. (2019). Comparison of tumor-targeting properties of directly and indirectly radioiodinated designed ankyrin repeat protein (DARPin) G3 variants for molecular imaging of HER2. International Journal of Oncology, 54(4), 1209-1220
Open this publication in new window or tab >>Comparison of tumor-targeting properties of directly and indirectly radioiodinated designed ankyrin repeat protein (DARPin) G3 variants for molecular imaging of HER2
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2019 (English)In: International Journal of Oncology, ISSN 1019-6439, Vol. 54, no 4, p. 1209-1220Article in journal (Refereed) Published
Abstract [en]

Evaluation of human epidermal growth factor receptor 2 (HER2) expression levels in breast and gastroesophageal cancer is used for the stratification of patients for HER2-targeting therapies. The use of radionuclide molecular imaging may facilitate such evaluation in a non-invasive way. Designed ankyrin repeat proteins (DARPins) are engineered scaffold proteins with high potential as probes for radionuclide molecular imaging. DARPin G3 binds with high affinity to HER2 and may be used to visualize this important therapeutic target. Studies on other engineered scaffold proteins have demonstrated that selection of the optimal labeling approach improves the sensitivity and specificity of radionuclide imaging. The present study compared two methods of labeling G3, direct and indirect radioiodination, to select an approach providing the best imaging contrast. G3-H-6 was labeled with iodine-124, iodine-125 and iodine-131 using a direct method. A novel construct bearing a C-terminal cysteine, G3-GGGC, was site-specifically labeled using [I-125]I-iodo-[(4-hydroxyphenyl)ethyl]maleimide (HPEM). The two radiolabeled G3 variants preserved binding specificity and high affinity to HER2-expressing cells. The specificity of tumor targeting in vivo was demonstrated. Biodistribution comparison of [I-131]I-G3-H-6 and [I-125]I-HPEM-G3-GGGC in mice, bearing HER2-expressing SKOV3 xenografts, demonstrated an appreciable contribution of hepatobiliary excretion to the clearance of [I-125]I-HPEM-G3-GGGC and a decreased tumor uptake compared to [I-131]I-G3-H-6. The direct label provided higher tumor-to-blood and tumor-to-organ ratios compared with the indirect label at 4 h post-injection. The feasibility of high contrast PET/CT imaging of HER2 expression in SKOV3 xenografts in mice using [I-124]I-G3-H-6 was demonstrated. In conclusion, direct radioiodination is the preferable approach for labeling DARPin G3 with iodine-123 and iodine-124 for clinical single photon emission computed tomography and positron emission tomography imaging.

Place, publisher, year, edition, pages
SPANDIDOS PUBL LTD, 2019
Keywords
DARPin, HER2, imaging, radionuclide, iodine, radioiodination
National Category
Radiology, Nuclear Medicine and Medical Imaging Cancer and Oncology
Identifiers
urn:nbn:se:uu:diva-380422 (URN)10.3892/ijo.2019.4712 (DOI)000461097600006 ()
Funder
Swedish Research Council, 2015-02353Swedish Research Council, 2015-02509Vinnova, 2016-04060Swedish Cancer Society, 2015/350Swedish Cancer Society, 2017/425
Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-04-02Bibliographically approved
Vorobyeva, A., Schulga, A., Konovalova, E., Guler, R., Lofblom, J., Sandström, M., . . . Deyev, S. M. (2019). Optimal composition and position of histidine-containing tags improves biodistribution of Tc-99m-labeled DARP in G3. Scientific Reports, 9, Article ID 9405.
Open this publication in new window or tab >>Optimal composition and position of histidine-containing tags improves biodistribution of Tc-99m-labeled DARP in G3
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 9405Article in journal (Refereed) Published
Abstract [en]

Radionuclide molecular imaging of HER2 expression in disseminated cancer enables stratification of patients for HER2-targeted therapies. DARP in G3, a small (14 kDa) engineered scaffold protein, is a promising probe for imaging of HER2. We hypothesized that position (C- or N-terminus) and composition (hexahistidine or (HE)(3)) of histidine-containing tags would influence the biodistribution of [Tc-99m]Tc(CO)(3)-labeled DARP in G3. To test the hypothesis, G3 variants containing tags at N-terminus (H-6-G3 and (HE)(3)-G3) or at C-terminus (G3-H-6 and G3-(HE)(3)) were labeled with [Tc-99m]Tc(CO)(3). Labeling yield, label stability, specificity and affinity of the binding to HER2, biodistribution and tumor targeting properties of these variants were compared side-by-side. There was no substantial influence of position and composition of the tags on binding of [Tc-99m]Tc(CO)(3)-labeled variants to HER2. The specificity of HER2 targeting in vivo was confirmed. The tumor uptake in BALB/c nu/nu mice bearing SKOV3 xenografts was similar for all variants. On the opposite, there was a strong influence of the tags on uptake in normal tissues. The tumor-to-liver ratio for [Tc-99m]Tc(CO)(3)-(HE)(3)-G3 was three-fold higher compared to the hexahistidine-tag containing variants. Overall, [Tc-99m]Tc(CO)(3)-(HE)(3)-G3 variant provided the highest tumor-to-lung, tumor-to-liver, tumor-to-bone and tumor-to-muscle ratios, which should improve sensitivity of HER2 imaging in these common metastatic sites.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Radiology, Nuclear Medicine and Medical Imaging Cancer and Oncology
Identifiers
urn:nbn:se:uu:diva-390813 (URN)10.1038/s41598-019-45795-8 (DOI)000473130000026 ()31253840 (PubMedID)
Funder
Swedish Research Council, 2015-02353Swedish Research Council, 2015-02509
Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-16Bibliographically approved
Liu, H., Lindbo, S., Ding, H., Altai, M., Garousi, J., Orlova, A., . . . Graslund, T. (2019). Potent and specific fusion toxins consisting of a HER2-binding, ABD-derived affinity protein, fused to truncated versions of Pseudomonas exotoxin A. International Journal of Oncology, 55(1), 309-319
Open this publication in new window or tab >>Potent and specific fusion toxins consisting of a HER2-binding, ABD-derived affinity protein, fused to truncated versions of Pseudomonas exotoxin A
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2019 (English)In: International Journal of Oncology, ISSN 1019-6439, Vol. 55, no 1, p. 309-319Article in journal (Refereed) Published
Abstract [en]

Fusion toxins consisting of an affinity protein fused to toxic polypeptides derived from Pseudomonas exotoxin A (ETA) are promising agents for targeted cancer therapy. In this study, we examined whether fusion toxins consisting of an albumin binding domain-derived affinity protein (ADAPT) interacting with human epidermal growth factor receptor 2 (HER2), coupled to the ETA-derived polypeptides PE38X8 or PE25, with or without an albumin binding domain (ABD) for half-life extension, can be used for specific killing of HER2-expressing cells. The fusion toxins could easily be expressed in a soluble form in Escherichia coli and purified to homogeneity. All constructs had strong affinity for HER2 (K-D 10 to 26 nM) and no tendency for aggregation could be detected. The fusion toxins including the ABD showed strong interaction with human and mouse serum albumin [equilibrium dissociation constant (K-D) 1 to 3 nM and 2 to 10 nM, respectively]. The in vitro investigation of the cytotoxic potential revealed IC50-values in the picomolar range for cells expressing high levels of HER2. The specificity was also demonstrated, by showing that free HER2 receptors on the target cells are required for fusion toxin activity. In mice, the fusion toxins containing the ABD exhibited an appreciably longer time in circulation. The uptake was highest in liver and kidney. Fusion with PE25 was associated with the highest hepatic uptake. Collectively, the results suggest that fusion toxins consisting of ADAPTs and ETA-derivatives are promising agents for targeted cancer therapy.

Keywords
exotoxin A, Pseudomonas, ABD-derived affinity protein, half-life extension, cancer, human epidermal growth factor receptor 2
National Category
Biochemistry and Molecular Biology Cancer and Oncology
Identifiers
urn:nbn:se:uu:diva-392048 (URN)10.3892/ijo.2019.4814 (DOI)000476557600026 ()31180549 (PubMedID)
Funder
Vinnova, 2016-04060Swedish Cancer Society, CAN 2015/746
Available from: 2019-09-10 Created: 2019-09-10 Last updated: 2019-09-10Bibliographically approved
von Witting, E., Garousi, J., Lindbo, S., Vorobyeva, A., Altai, M., Oroujeni, M., . . . Tolmachev, V. (2019). Selection of the optimal macrocyclic chelators for labeling with 111In and 68Ga improves contrast of HER2 imaging using engineered scaffold protein ADAPT6. European journal of pharmaceutics and biopharmaceutics, 140, 109-120
Open this publication in new window or tab >>Selection of the optimal macrocyclic chelators for labeling with 111In and 68Ga improves contrast of HER2 imaging using engineered scaffold protein ADAPT6
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2019 (English)In: European journal of pharmaceutics and biopharmaceutics, ISSN 0939-6411, E-ISSN 1873-3441, Vol. 140, p. 109-120Article in journal (Refereed) Published
Abstract [en]

Radionuclide molecular imaging is a promising tool that becomes increasingly important as targeted cancer therapies are developed. To ensure an effective treatment, a molecular stratification of the cancer is a necessity. To accomplish this, visualization of cancer associated molecular abnormalities in vivo by molecular imaging is the method of choice. ADAPTs, a novel type of small protein scaffold, have been utilized to select and develop high affinity binders to different proteinaceous targets. One of these binders, ADAPT6 selectively interacts with human epidermal growth factor 2 (HER2) with low nanomolar affinity and can therefore be used for its in vivo visualization. Molecular design and optimization of labeled anti-HER2 ADAPT has been explored in several earlier studies, showing that small changes in the scaffold affect the biodistribution of the domain. In this study, we evaluate how the biodistribution properties of ADAPT6 is affected by the commonly used maleimido derivatives of the macrocyclic chelators NOTA, NODAGA, DOTA and DOTAGA with the aim to select the best variants for SPECT and PET imaging. The different conjugates were labeled with 111In for SPECT and 68Ga for PET. The acquired data show that the combination of a radionuclide and a chelator for its conjugation has a strong influence on the uptake of ADAPT6 in normal tissues and thereby gives a significant variation in tumor-toorgan ratios. Hence, it was concluded that the best variant for SPECT imaging is 111In-(HE)3DANS-ADAPT6-GSSC-DOTA while the best variant for PET imaging is 68Ga-(HE)3DANS-ADAPT6-GSSC-NODAGA.

Keywords
ADAPT, HER2, Radionuclide imaging, Indium-111, Gallium-68, DOTA, NOTA, NODAGA, DOTAGA
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy) Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-388759 (URN)10.1016/j.ejpb.2019.05.008 (DOI)000470947400012 ()31082509 (PubMedID)
Funder
Swedish Research Council, 2015-02353Swedish Research Council, 2015-02509Vinnova, 2016-04060Swedish Cancer Society, CAN 2018/436Swedish Cancer Society, 2017/425
Note

De 2 första författarna delar förstaförfattarskapet.

Available from: 2019-08-14 Created: 2019-08-14 Last updated: 2019-08-14Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-7224-6304

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