Rapid Target Binding and Cargo Release of Activatable Liposomes Bearing HER2 and FAP Single-Chain Antibody Fragments Reveal Potentials for Image-Guided Delivery to Tumors.

Felista L Tansi,Roland E Kontermann,Ingrid Hilger,Ulf K Teichgräber,Ronny Rüger,Claudia Böhm,Alfred Fahr,Alexander S Mosig,Frank Steiniger,Martin Raasch

doi:10.3390/pharmaceutics12100972

Felista L Tansi, Roland E Kontermann + Show 8 more

Open Access

https://doi.org/10.3390/pharmaceutics12100972

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Abstract

Liposomes represent suitable tools for the diagnosis and treatment of a variety of diseases, including cancers. To study the role of the human epidermal growth factor receptor 2 (HER2) as target in cancer imaging and image-guided deliveries, liposomes were encapsulated with an intrinsically quenched concentration of a near-infrared fluorescent dye in their aqueous interior. This resulted in quenched liposomes (termed LipQ), that were fluorescent exclusively upon degradation, dye release, and activation. The liposomes carried an always-on green fluorescent phospholipid in the lipid layer to enable tracking of intact liposomes. Additionally, they were functionalized with single-chain antibody fragments directed to fibroblast activation protein (FAP), a marker of stromal fibroblasts of most epithelial cancers, and to HER2, whose overexpression in 20–30% of all breast cancers and many other cancer types is associated with a poor treatment outcome and relapse. We show that both monospecific (HER2-IL) and bispecific (Bi-FAP/HER2-IL) formulations are quenched and undergo HER2-dependent rapid uptake and cargo release in cultured target cells and tumor models in mice. Thereby, tumor fluorescence was retained in whole-body NIRF imaging for 32–48 h post-injection. Opposed to cell culture studies, Bi-FAP/HER2-IL-based live confocal microscopy of a high HER2-expressing tumor revealed nuclear delivery of the encapsulated dye. Thus, the liposomes have potentials for image-guided nuclear delivery of therapeutics, and also for intraoperative delineation of tumors, metastasis, and tumor margins.

Highlights

Optical fluorescence imaging in combination with drug delivery systems unifies properties that can advance image-guided medicine
After extrusion through a 100 nm polycarbonate membrane, the liposomes were post-inserted with micelles that were preconjugated to fibroblast activation protein (FAP)- and/or human epidermal growth factor receptor 2 (HER2)-specific scFv in order to make them selective for FAP and HER2 expressing cells
Monospecific liposomes were post-inserted with the respective FAP’scFv or HER2’scFv MALPEG2000-DSPE micelles (Figure 1A, FAP-IL and HER2-IL) whereas bispecific liposomes were post-inserted with both micelles (Figure 1A, Bi-FAP/HER2-IL)

Summary

Introduction

Optical fluorescence imaging in combination with drug delivery systems unifies properties that can advance image-guided medicine These features can be exploited for example to promote early cancer diagnosis based on fluorescence imaging and to enhance the real-time visualization of tumor margins during oncologic surgery [1,2]. Due to their biocompatibility, liposomes which are lipidic nanovesicles that mimic biological membranes are widely used for the delivery of drugs or contrast agents, both in clinical and preclinical setups [3,4,5]. The human epidermal growth factor receptor 2 (HER2), for example, represents such a conspicuous heterogeneous tumor marker that has attracted research interest

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