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Two-Step Targeting for Effective Radionuclide Therapy: Preclinical Evaluation of 125I-labelled Anthracycline Delivered by Tumour Targeting Liposomes
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Biomedical Radiation Sciences.
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

For the treatment of cancer, Auger-electron emitting radionuclides are strongly dependent on their close proximity to DNA to utilize the local therapeutic potential of the Auger electrons. This thesis investigates a two-step targeting approach that uses targeting liposomes for the delivery of an Auger-electron emitter, 125I, coupled to a DNA-binding compound, Comp1, to the tumour-cell DNA. In the first step the liposome targets overexpressed cell-surface receptors. Receptors belonging to epidermal growth factor receptor (EGFR) family are overexpressed in a number of different cancers and are therefore suitable targets. The second step is transportation of the radionuclide to the cell nucleus utilizing a DNA-binding compound. The DNA-binder used in this thesis is a daunorubicin derivative called Comp1. Papers I and II are in vitro characterizations of the targeting liposomes. Both EGFR- and HER2-targeting liposomes delivered 125I-Comp1 receptor specifically to tumour cells, and were efficient in decreasing growth of cultured tumour cells. Paper II also included a biodistribution of 125I-Comp1 delivered by HER2-targeting liposomes in tumour-bearing mice. The results gave a time-dependent uptake in tumours differed from when non-targeting liposomes encapsulating 125I-Comp1 were given. Paper III investigates the therapeutic effect of 125I-Comp1 delivered by HER2-targeting liposomes, in an animal model that mimics a situation of disseminated tumour cells in the abdomen. 125I-Comp1 delivered by HER2-targeting liposomes effectively prolonged survival of the mice in a dose-dependent relation. Several mice in the groups receiving the highest doses were tumour-free at the end of the study. Paper IV compares different lipid compositions of the liposomes with respect to leakage, cellular uptake and therapeutic efficacy of delivered 125I-Comp1on cultured cells. Liposomes containing sphingomyelin or dihydrosphingomyelin retained drug more efficiently and exhibited more receptor specific delivery properties than distearoylglycerophosphatidylcholine (DSPC) containing liposomes. However, it was the DSPC-containing liposomes that displayed best growth inhibition on cultured tumour cells. The thesis concludes that 125I-Comp1 delivered by targeting liposomes is a promising candidate for effective radionuclide therapy.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2011. , 100 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 708
Keyword [en]
radionuclide, Auger electrons, liposomes, targeting, tumour therapy
National Category
Other Basic Medicine
Research subject
Biomedical Radiation Science
Identifiers
URN: urn:nbn:se:uu:diva-159365ISBN: 978-91-554-8172-8 (print)OAI: oai:DiVA.org:uu-159365DiVA: diva2:444501
Public defence
2011-11-12, Rudbecksalen, Dag Hammarskjölds väg 20, Uppsala, 09:15 (Swedish)
Opponent
Supervisors
Available from: 2011-10-21 Created: 2011-09-29 Last updated: 2011-11-04Bibliographically approved
List of papers
1. Nuclisome: a novel concept for radionuclide therapy using targeting liposomes
Open this publication in new window or tab >>Nuclisome: a novel concept for radionuclide therapy using targeting liposomes
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2010 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 37, no 1, 114-123 p.Article in journal (Refereed) Published
Abstract [en]

PURPOSE: For the treatment of cancer, the therapeutic potential of short-range, low-energy Auger-electron emitters, such as (125)I, is getting progressively wider recognition. The potency of Auger-electron emitters is strongly dependent on their location in close vicinity to DNA. We have developed a new two-step targeting strategy to transport (125)I into cancer-cell nuclei using PEG-stabilized tumour-cell targeting liposomes named "Nuclisome-particles". METHODS: In the present study, epidermal growth factor (EGF) was used as a tumour-cell-specific agent to target the EGF-receptor (EGFR) and the liposomes were loaded with (125)I-Comp1, a recently synthesized daunorubicin derivative. RESULTS: As analysed with cryo-TEM, the derivative precipitates inside liposomes at a drug-to-lipid molar ratio of 0.05:1. Receptor-specific uptake in cultured U-343MGaCl2:6 tumour cells of EGFR-targeting liposomes increased with time while non-specific and receptor-blocked uptake remained low. Nuclisome-particles were able to target single U-343MGaCl2:6 cells circulating in human blood during 4 h, with low uptake in white blood cells, as demonstrated in an ex vivo system using a Chandler loop. Autoradiography of targeted cells indicates that the grains from the radiolabelled drug are mainly co-localized with the cell nuclei. The successful targeting of the nucleus is shown to provide high-potency cell killing of cultured U-343MGaCl2:6 cells. At the concentration used, Nuclisome-particles were up to five orders of magnitude more effective in cell killing than EGFR-targeting liposomes loaded with doxorubicin. CONCLUSION: The results thus provide encouraging evidence that our two-step targeting strategy for tumour cell DNA has the potential to become an effective therapy against metastasizing cancer cells in the bloodstream.

Keyword
Targeting liposomes, EGF, Radionuclide therapy, Anthracyclines, Auger-electron emitter
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-125921 (URN)10.1007/s00259-009-1225-7 (DOI)000272615700014 ()19662408 (PubMedID)
Available from: 2010-05-31 Created: 2010-05-31 Last updated: 2017-12-12Bibliographically approved
2. In vitro evaluation and biodistribution of HER2-targeted liposomes loaded with an 125I-labelled DNA-intercalator
Open this publication in new window or tab >>In vitro evaluation and biodistribution of HER2-targeted liposomes loaded with an 125I-labelled DNA-intercalator
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2011 (English)In: Journal of drug targeting (Print), ISSN 1061-186X, E-ISSN 1029-2330, Vol. 19, no 9, 846-855 p.Article in journal (Refereed) Published
Abstract [en]

Background: Increasing attention is currently focussed on the issue of finding strategies for the delivery of Auger-electron emitting radionuclides into tumour cell nuclei. Nuclear localisation is a prerequisite for these radionuclides, since their radiotoxic properties are functional only in close vicinity to DNA.

Purpose: In this study we investigated tumour-cell uptake and cell killing ability in vitro, as well as in vivo biodistribution of an 125I-labelled anthracycline derivative administered by means of HER2-targeted liposomes.

Methods: Anthracycline derivative Comp1 was radiolabelled with Auger-emitting 125I and encapsulated in liposomes (DSPC:Chol:DSPE-PEG) using pH-gradient loading. Single-chain fragment F5 was anchored to the liposomes as targeting device for HER2. Uptake and specificity of 125I-Comp1 delivered via targeting and non-targeting liposomes were analysed in cultured HER2-overexpressing SKOV3 and SKBR3 cells. Cell-killing efficacy was evaluated in SKOV3 cells and biodistribution for up to 48 hours was studied after intra-peritoneal injection in tumour-bearing female Balb/c nu/nu mice.

Results: 125I-Comp1 was specifically taken up by the cultured cells when administered by means of HER2-targeted liposomes and a clear dose-effect correlation in survival of cells was seen with increasing specific activity. The biodistribution studies revealed that 125I-Comp1 accumulated in tumours when distributed using HER2-targeted liposomes and that this effect was absent when using non-targeting liposomes.

Conclusion: The HER2-targeted liposomes possess the properties needed to bring about tumour-specific delivery and therapeutic effect of 125I-Comp1.

 

National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-147028 (URN)10.3109/1061186X.2011.589436 (DOI)000295889800013 ()
Available from: 2011-02-23 Created: 2011-02-23 Last updated: 2017-12-11Bibliographically approved
3. Experimental radionuclide therapy of HER2-expressing xenografts using two-step targeting Nuclisome-particles
Open this publication in new window or tab >>Experimental radionuclide therapy of HER2-expressing xenografts using two-step targeting Nuclisome-particles
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2012 (English)In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 53, no 3, 480-487 p.Article in journal (Refereed) Published
Abstract [en]

The therapeutic potential of Auger-electron emitting radionuclides is strongly dependent on their close vicinity to DNA, since the energy deposition is mainly localized within a few cubic nanometers around the site of decay. Thus, apart from specificity, successful tumor therapy relies on a nuclear delivery strategy. We recently presented a two-step targeting strategy to transport Auger-electron-emitting radionuclides into the cell nucleus by means of nuclide-filled liposomes (Nuclisome particles), that is, polyethylene glycol-stabilized, tumor-cell-targeting liposomes loaded with (125)I-labeled anthracyclines. In the present study, the survival of mice intraperitoneally inoculated with human HER2-expressing SKOV-3 tumor cells and treated with HER2-targeting Nuclisome particles was studied.

METHODS:

BALB/c nu/nu mice were inoculated with 10(7) SKOV-3 cells intraperitoneally and thereafter directly injected with Nuclisome particles with increasing specific radioactivity. Groups of 10-12 mice were treated with 0.01 MBq/mouse up to 2 MBq/mouse, and survival was monitored and compared with that in control groups (n = 33). Organs were analyzed for HER2 expression and radiotoxic effects histologically. Absorbed doses were estimated using dose factors from the online Radiation Dose Assessment Resource model.

RESULTS:

The results showed a clear correlation between administered radioactive dose and survival. No such dose-dependent survival was observed for mice treated with Nuclisome particles lacking HER2-targeting ability. With HER2-targeting Nuclisome particles, a significant increase in survival, compared with that of untreated control mice, could already be seen at an administered activity of 0.1 MBq/mouse (P = 0.0301). At the highest activity administered, 2 MBq/mouse (P < 0.0001), 70% of the mice survived the study and most were tumor-free. Neither macroscopic nor microscopic radiotoxic side effects were observed. Dosimetric calculations, assuming nonreceptor targeting, revealed that the radioactive doses to normal tissues were low.

CONCLUSION:

Taken together the results show that with successful targeting to the tumor-cell nucleus it is possible to obtain a therapeutic effect from Auger-electron-emitting radionuclides administered at radioactive doses low enough to spare normal tissue from radiotoxic side effects.

National Category
Other Basic Medicine
Identifiers
urn:nbn:se:uu:diva-158992 (URN)10.2967/jnumed.111.096891 (DOI)000301194300046 ()22323773 (PubMedID)
Available from: 2011-09-20 Created: 2011-09-20 Last updated: 2017-12-08Bibliographically approved
4. Influence of liposome composition on cellular drug delivery and therapeutic effect mediated by Nuclisome-particles
Open this publication in new window or tab >>Influence of liposome composition on cellular drug delivery and therapeutic effect mediated by Nuclisome-particles
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(English)Manuscript (preprint) (Other academic)
National Category
Other Basic Medicine
Identifiers
urn:nbn:se:uu:diva-158994 (URN)
Available from: 2011-09-20 Created: 2011-09-20 Last updated: 2011-11-04

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