CD8 Minibody PET Imaging for Tumor Infiltration Detection
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Solution Overview
Problem
Current methods for monitoring and treating CD8-positive cells in vivo are limited in their ability to accurately visualize and quantify CD8-positive cells in tissues, particularly in detecting low densities and infiltrating lymphocytes within tumors, which is crucial for effective cancer immunotherapy.
Innovation Solution
A method involving the administration of a CD8 minibody labeled with a detectable marker, such as 89Zr, which binds to CD8-positive cells, allowing for PET imaging to visualize and quantify CD8-positive cells within 6-36 hours, enabling the detection of tissues with low CD8-positive cell densities and determining tumor-infiltrating lymphocyte status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging methods are used to monitor CD8-positive cells, then the ability to visualize cells is limited, but the sensitivity to detect low densities and infiltrating lymphocytes is insufficient
Solution Approach 1:
The patent uses a minibody as an intermediary agent that specifically binds to CD8-positive cells. This minibody serves as a mediator between the imaging system and the target cells, enabling detection of low-density CD8+ cells that are difficult to visualize with conventional methods. The minibody conjugated to a detectable marker acts as the intermediary that bridges the gap between the imaging capabilities and the target cell detection requirements.
Solution Approach 2:
The patent changes the parameter of detectable marker labeling on the minibody to enhance detection sensitivity. By incorporating radiolabeled or fluorescently labeled markers on the minibody, the imaging parameters are modified to enable sensitive detection of low-density CD8+ cell populations. This parameter change allows the system to detect and measure low-density infiltrating lymphocytes that were previously undetectable.
2Measurement precision
If CD8 minibody with detectable marker is administered, then CD8-positive cells can be visualized and quantified, but the complexity of the imaging protocol increases
Solution Approach 1:
The patent segments the imaging protocol into distinct temporal phases: administration of the minibody, circulation period (6-36 hours), and imaging acquisition. This segmentation allows for optimized conditions at each stage - the minibody has time to bind to CD8+ cells during circulation, then the imaging system can specifically detect the labeled minibody-bound complexes. This temporal segmentation simplifies the overall protocol by separating the binding phase from the detection phase.
Solution Approach 2:
The patent uses a detectable marker as a copy or proxy for the CD8-positive cells themselves. Instead of directly imaging the CD8+ cells which are difficult to detect, the system images the minibody marker that copies the location and distribution of the CD8+ cells. This copying approach simplifies the imaging protocol by replacing the difficult direct detection task with an easier indirect detection through the labeled minibody.
3Measurement precision
If the minibody is labeled with detectable marker such as 89Zr, then PET imaging can detect CD8-positive cells within 6-36 hours, but the radiation dose to the subject increases
Solution Approach 1:
The patent uses a partial action approach by administering a relatively small amount of radiolabeled minibody (0.75-1.5 mCi) rather than a full diagnostic dose. This partial action is sufficient to achieve the detection timing requirement of 6-36 hours while minimizing the radiation dose. The minibody's high affinity binding to CD8+ cells ensures that even this partial dose provides adequate signal for quantification without excessive radiation exposure.
Solution Approach 2:
The patent employs a short-living radiolabeled minibody that decays relatively quickly (89Zr has a half-life of about 78 hours) compared to longer-lived radiotracers. This short-living characteristic allows the system to achieve detection within 6-36 hours while the radiation dose is limited by the short half-life. The minibody serves as a disposable tracer that performs its detection function and then decays, minimizing long-term radiation exposure to the subject.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables non-invasive monitoring and characterization of CD8-positive cells, facilitating the selection of appropriate immunotherapy by determining the immune phenotype of tumors and guiding treatment decisions based on CD8-positive cell infiltration.
Implementation Method 1
the CD8 minibody binds to a CD8 as shown in FIG. 1C
Implementation Method 2
the minibody is labeled with a detectable marker, such as 89Zr
Implementation Method 3
allowing for PET imaging to visualize and quantify CD8-positive cells
Data Source
Figure 1A~1B
Figure 1C
Figure 2A
AI summary
Antigen binding constructs that bind to CD8, as well as formulations and methods of using them, are described herein.