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Maleimide-thiol linkages alter the biodistribution of SN38 therapeutic microbubbles compared to biotin-avidin while preserving parity in tumoral drug delivery

Yes / Therapeutic microbubbles (thMBs) contain drug-filled liposomes linked to microbubbles and targeted to vascular proteins. Upon the application of a destructive ultrasound trigger, drug uptake to tumour is improved. However, the structure of thMBs currently uses powerful non-covalent bonding of biotin with avidin-based proteins to link both the liposome to the microbubble (MB) and to bind the targeting antibody to the liposome-MB complex. This linkage is not currently FDA-approved, and therefore, an alternative, maleimide-thiol linkage, that is currently used in antibody-drug conjugates was examined. In a systematic manner, vascular endothelial growth factor receptor 2 (VEGFR2)-targeted MBs and thMBs using both types of linkages were examined for their ability to specifically bind to VEGFR2 in vitro and for their ultrasound imaging properties in vivo. Both showed equivalence in the production of the thMB structure, in vitro specificity of binding and safety profiles. In vivo imaging showed subtle differences for thMBs where biotin thMBs had a faster wash-in rate than thiol thMBs, but thiol thMBs were longer-lived. The drug delivery to tumours was also equivalent, but interestingly, thiol thMBs altered the biodistribution of delivery away from the lungs and towards the liver compared to biotin thMBs, which is an improvement in biosafety. / This research was funded by the EPSRC (EP/I000623/1, EP/L504993/1 and EP/P023266/1). S.D.E. is supported by the National Institute for Health Research infrastructure at Leeds.

Identiferoai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/19981
Date29 August 2024
CreatorsIngram, N., Abou-Saleh, R.H., Race, Amanda D., Loadman, Paul, Bushby, R.J., Evans, S.D., Coletta, P.L.
PublisherMDPI
Source SetsBradford Scholars
LanguageEnglish, English
Detected LanguageEnglish
TypeArticle, Published version
Rights© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/)., CC-BY

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