APRIL-Based CAR Structure for Low-BCMA Myeloma Targeting
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Solution Overview
Problem
Current treatments for multiple myeloma, a bone-marrow malignancy of plasma cells, are largely ineffective, and existing chimeric antigen receptors (CARs) targeting B-cell maturation antigen (BCMA) face challenges due to the low density of BCMA expression on myeloma cells, necessitating improved sensitivity and specificity for effective cell recognition.
Innovation Solution
A chimeric antigen receptor (CAR) design utilizing a truncated form of the proliferation-inducing ligand (APRIL) as the BCMA-binding domain, combined with a spacer and intracellular signaling domains, enhances the sensitivity and specificity of T-cell recognition and killing of BCMA-expressing cells, even those with low BCMA expression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CARs targeting BCMA are used, then T-cell recognition of BCMA-expressing cells is achieved, but the sensitivity is insufficient due to low BCMA density on myeloma cells
Solution Approach 1:
The patent changes the binding domain from conventional scFv to a modified APRIL protein with altered structural parameters. The truncated APRIL lacking the amino-terminal proteoglycan-binding region, combined with specific spacer domain designs (IgG1 hinge, CD8 stalk, or IgG1 Fc), modifies the receptor's binding characteristics to enhance sensitivity for low-density BCMA targets.
Solution Approach 2:
The patent introduces intermediary spacer domains between the APRIL binding domain and the transmembrane/signaling domains. These spacers (IgG1 hinge, CD8 stalk, IgG1 Fc) act as mediators that optimize the spatial arrangement and binding dynamics, enabling effective recognition of low-density BCMA expressions.
2Reliability
If conventional CARs targeting BCMA are used, then T-cell killing activity is achieved, but the specificity is reduced due to low BCMA density expression
Solution Approach 1:
The patent modifies the binding domain parameters by using truncated APRIL without the amino-terminal region, which changes the binding specificity to be more selective for BCMA. This parameter change enhances specificity by reducing off-target binding while maintaining effectiveness against low-density BCMA-expressing myeloma cells.
3Productivity
If standard CAR design is used against low BCMA density targets, then treatment approach is established, but killing efficiency is insufficient
Solution Approach 1:
The patent employs parameter changes in the CAR structure, specifically using truncated APRIL binding domains with modified spacer domains (IgG1 hinge, CD8 stalk, IgG1 Fc). These structural modifications enhance the receptor's ability to detect and respond to low-density BCMA, thereby significantly improving killing efficiency against myeloma cells with low antigen expression.
Solution Approach 2:
The patent creates a composite CAR structure combining truncated APRIL binding domain with various spacer domain types (IgG1 hinge, CD8 stalk, IgG1 Fc) and transmembrane/signaling domains. This composite design integrates multiple functional elements to achieve enhanced sensitivity and killing efficiency against low-BCMA-density targets.
Data Source
AI summary
The present invention provides a chimeric antigen receptor (CAR) comprising: (i) a B cell maturation antigen (BCMA)-binding domain which comprises at least part of a proliferation-inducing ligand (APRIL); (ii) a spacer domain (iii) a transmembrane domain; and (iv) an intracellular T cell signaling domain. The invention also provides the use of such a T-cell expressing such a CAR in the treatment of plasma-cell mediated diseases, such as multiple myeloma.