Antibody-Displaying Extracellular Vesicles for Targeted Cancer Therapy
The Application of Antibodies Displaying Extracellular Vesicles in Targeted Cancer Therapy
Extracellular Vesicles (EVs) have been extensively researched as natural delivery carriers and mediators of biological signals in various tissues. In this study, researchers utilized these characteristics of EVs to demonstrate a modular delivery system for cancer-targeted therapy, decorated with specific antibody binding domains (Fragment crystallizable, Fc). The study was published in “Nature Biomedical Engineering” and was completed by an international collaborative team, including Oscar P. B. Wiklander, Doste R. Mamand, Dara K. Mohammad, among others, from several renowned research institutions like Karolinska Institutet, Salahaddin University-Erbil, and University of Oxford.
Research Background and Purpose
One of the major advancements in cancer treatment over the past few decades is the application of antibody-targeted therapies, such as the anti-HER2 (Human Epidermal Receptor 2) treatment for breast cancer, and recently, immunotherapies including immune checkpoint inhibitors. Despite the high expression of PD-L1 (Programmed-Death Ligand 1) in various tumors, only a small fraction of patients exhibit persistent responses. Consequently, numerous strategies have been proposed to enhance conversion rates, including combining with chemotherapy, inhibiting multiple checkpoints, and other immunostimulatory methods. However, these strategies face limitations in coordinating the delivery of different types of drugs to target sites.
Extracellular Vesicles offer an intriguing alternative as nanoscale carriers for drug delivery. EVs are a heterogeneous group of naturally secreted nano-vesicles by all cells, ranging from 30 to 2000 nanometers in diameter, capable of carrying lipid, protein, and nucleic acid substances derived from cells, and transferring them through advanced intercellular communication systems. EVs can not only cross biological barriers to reach distant organs but can also be engineered to display targeting groups and carry various therapeutic cargoes. Over the past few years, the therapeutic potential of EVs has received increasing attention, with numerous clinical trials underway.
Research Process
Research Subjects and Engineering Methods
This study aimed to develop a highly modular EV-based therapeutic technology by utilizing molecular engineering tools to create EVs that can bind antibody Fc fragments, making them applicable for targeting any tissue of interest. The research team first introduced an Fc-binding domain on the EV surface to decorate various types of antibodies, allowing EVs to target specific tissues. Cells generating EVs were engineered to express fusion constructs, including Fc-binding domains and EV classification proteins, thereby enriching Fc domains on EVs.
Researchers compared nine EV classification domains (such as CD9, CD63, CD81, etc.) and nine Fc-binding domains (like Protein A, Z domain, etc.) engineering strategies, and used Imaging Flow Cytometry (IFC) to screen and measure the fluorescence reporter gene and antibody binding on EVs.
Experimental Steps and Major Findings
EV Engineering and Screening:
- Initial screening found that the combination of CD63 and Z domain produced the highest level of expression, making it the best candidate for subsequent experiments.
EV Characterization and Antibody Binding Confirmation:
- Through Nanoparticle Tracking Analysis (NTA), it was determined that the particle size of Fc-EVs was about 100 nanometers.
- Immunoelectron microscopy and size-exclusion chromatography further confirmed the specific binding of Fc-EVs to antibodies.
In Vitro Targeting Ability Evaluation:
- In targeting experiments on HER2-positive breast cancer cells (SKBR-3) using anti-HER2 antibody (Trastuzumab), Fc-EVs showed a significant increase in endocytosis.
- In experiments on PD-L1 expressing malignant melanoma cells (B16F10) using anti-PD-L1 antibody (Atezolizumab), a similar significant increase in endocytosis was observed.
In Vivo Targeting Experiments:
- In the B16F10 tumor mouse model, intravenous injection of Fc-EVs demonstrated significant tumor tissue accumulation, especially Fc-EVs displaying anti-PD-L1 antibodies showed higher tumor-targeting accumulation effects.
Drug Delivery and Therapeutic Effect:
- Fc-EVs loaded with doxorubicin showed significant inhibition of tumor progression and prolonged survival in melanoma mouse models, demonstrating their potential as a cancer-targeted delivery vehicle.
Research Conclusions and Significance
This study demonstrated a highly modular EV-based therapeutic technology that, by displaying the antibody Fc domain, allows EVs to target specific tissues and deliver antitumor drugs. Compared to traditional antibody therapies, Fc-EVs provide a more precise drug delivery method, with significant scientific and application value. Due to the high flexibility of antibody display technology, Fc-EVs can combine with various approved therapeutic antibodies, providing a potential “ready-to-use” treatment option.
Research Highlights
- Modular Technology Innovation: The first demonstration of EVs that can be modularly designed to display Fc domains, significant for the targeted treatment of various cancers.
- Targeted Drug Delivery: Proved the feasibility of targeted drug delivery via EVs, especially in malignant tumors, with potential to reduce chemotherapy side effects.
- Multiple Application Potentials: The technology can be used not only for traditional antibodies but also extended to Fc fusion proteins, antibody-drug conjugates, and bispecific antibodies.
Future Outlook
This study lays a solid foundation for subsequent research. Future studies need to further explore the potential of Fc-EVs in different therapeutic combinations to achieve clinical translation. Overall, Fc-EVs, as an innovative cancer treatment vehicle, demonstrate great potential and practical application value and will play an important role in the future of precision medicine.