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Visualization, Quantification, and Mapping of Immune Cell Populations in the Tumor Microenvironment
Published on: March 25, 2020
Multiplex Three-Dimensional Mapping of Macromolecular Drug Distribution in the Tumor Microenvironment
Steve Seung-Young Lee1,2, Vytautas P Bindokas3, Stephen J Kron4,2
1Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois.
Abstract:
Macromolecular cancer drugs such as therapeutic antibodies and nanoparticles are well known to display slow extravasation and incomplete penetration into tumors, potentially protecting cancer cells from therapeutic effects. Conventional assays to track macromolecular drug delivery are poorly matched to the heterogeneous tumor microenvironment, but recent progress on optical tissue clearing and three-dimensional (3D) tumor imaging offers a path to quantitative assays with cellular resolution. Here, we apply transparent tissue tomography (T3) as a tool to track perfusion and delivery in the tumor and to evaluate target binding and vascular permeability. Using T3, we mapped anti-programmed cell death protein-ligand 1 (PD-L1) antibody distribution in whole mouse tumors. By measuring 3D penetration distances of the antibody drug out from the blood vessel boundaries into the tumor parenchyma, we determined spatial pharmacokinetics of anti-PD-L1 antibody drugs in mouse tumors. With multiplex imaging of tumor components, we determined the distinct distribution of anti-PD-L1 antibody drug in the tumor microenvironment with different PD-L1 expression patterns. T3 imaging revealed CD31+ capillaries are more permeable to anti-PD-L1 antibody transport compared with the blood vessels composed of endothelium supported by vascular fibroblasts and smooth muscle cells. T3 analysis also confirmed that isotype IgG antibody penetrates more deeply into tumor parenchyma than anti-Her2 or anti-EGFR antibody, which were restrained by binding to their respective antigens on tumor cells. Thus, T3 offers simple and rapid access to 3D, quantitative maps of macromolecular drug distribution in the tumor microenvironment, offering a new tool for development of macromolecular cancer therapeutics.
Insights
Transparent tissue tomography (T3) enables quantitative 3D mapping of macromolecular cancer drug delivery within tumors. This method reveals how antibody penetration varies, aiding the development of more effective cancer therapeutics.
Area of Science:
- Oncology
- Biomedical Imaging
- Pharmacokinetics
Background:
- Macromolecular cancer drugs (antibodies, nanoparticles) face challenges with tumor penetration and extravasation, limiting efficacy.
- Conventional drug delivery assays struggle with the complex tumor microenvironment's heterogeneity.
- Advances in optical tissue clearing and 3D imaging offer potential for high-resolution quantitative drug delivery assessment.
Purpose of the Study:
- To introduce and validate Transparent Tissue Tomography (T3) as a tool for quantitative 3D analysis of macromolecular drug delivery in tumors.
- To map the spatial pharmacokinetics and distribution of anti-programmed cell death protein-ligand 1 (PD-L1) antibody drugs within whole mouse tumors.
- To evaluate the impact of tumor microenvironment components and antibody-target interactions on drug penetration.
Main Methods:
- Application of Transparent Tissue Tomography (T3) for whole-mouse tumor imaging and analysis.
- 3D mapping of anti-PD-L1 antibody distribution relative to blood vessels and tumor parenchyma.
- Multiplex imaging to correlate drug distribution with PD-L1 expression and other tumor components (e.g., CD31+ capillaries).
Main Results:
- T3 successfully mapped anti-PD-L1 antibody distribution in 3D within mouse tumors, quantifying penetration distances.
- Capillary permeability varied, with CD31+ capillaries showing higher permeability to anti-PD-L1 antibodies than other vessel types.
- Antibody penetration depth was influenced by target binding; isotype IgG penetrated deeper than antigen-bound anti-Her2 or anti-EGFR antibodies.
Conclusions:
- T3 provides rapid, quantitative, 3D insights into macromolecular drug distribution within the tumor microenvironment.
- This imaging technique can inform the development of novel macromolecular cancer therapeutics by optimizing delivery strategies.
- Understanding drug penetration dynamics is crucial for enhancing the effectiveness of antibody-based cancer treatments.
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