Related Experiment Video
Updated: Mar 2, 2026
Author Spotlight: Advancements in Hypoxia-Sensitive CAR-T Therapy for Enhanced Cancer Immunotherapy
Published on: June 14, 2024
A Rational Strategy for Reducing On-Target Off-Tumor Effects of CD38-Chimeric Antigen Receptors by Affinity
Esther Drent1, Maria Themeli1, Renée Poels1
1Department of Hematology, VU University Medical Center, De Boelelaan 1117, 1081HV Amsterdam, the Netherlands.
Abstract:
Chimeric antigen receptors (CARs) can effectively redirect cytotoxic T cells toward highly expressed surface antigens on tumor cells. The low expression of several tumor-associated antigens (TAAs) on normal tissues, however, hinders their safe targeting by CAR T cells due to on-target/off-tumor effects. Using the multiple myeloma (MM)-associated CD38 antigen as a model system, here, we present a rational approach for effective and tumor-selective targeting of such TAAs. Using "light-chain exchange" technology, we combined the heavy chains of two high-affinity CD38 antibodies with 176 germline light chains and generated ∼124 new antibodies with 10- to >1,000-fold lower affinities to CD38. After categorizing them into three distinct affinity classes, we incorporated the single-chain variable fragments of eight antibodies from each class into new CARs. T cells carrying these CD38-CARs were extensively evaluated for their on-tumor/off-tumor cytotoxicity as well as CD38-dependent proliferation and cytokine production. We identified CD38-CAR T cells of ∼1,000- fold reduced affinity, which optimally proliferated, produced Th1-like cytokines, and effectively lysed CD382+ MM cells, but spared CD38+ healthy hematopoietic cells in vitro and in vivo. Thus, this systematic approach is highly suitable for the generation of optimal CARs for effective and selective targeting of TAAs.
Insights
Researchers developed a new method to create safer chimeric antigen receptor (CAR) T-cells for cancer therapy. By fine-tuning antibody affinity, these CAR T-cells can precisely target multiple myeloma cells while sparing healthy tissues.
Area of Science:
- Immunotherapy
- Oncology
- Molecular Biology
Background:
- Chimeric antigen receptor (CAR) T-cells offer potent anti-tumor activity by targeting tumor-associated antigens (TAAs).
- On-target/off-tumor effects, caused by TAA expression on healthy tissues, limit CAR T-cell safety and efficacy.
- Targeting antigens with low expression on normal tissues requires a strategy to enhance tumor selectivity.
Purpose of the Study:
- To develop a rational approach for generating tumor-selective CAR T-cells targeting the multiple myeloma (MM)-associated CD38 antigen.
- To investigate the impact of antibody affinity modulation on CAR T-cell function and safety.
- To identify optimal CD38-CAR T-cells that effectively eliminate MM cells while sparing healthy hematopoietic cells.
Main Methods:
- Utilized "light-chain exchange" technology to generate a library of CD38 antibodies with a wide range of affinities.
- Created CD38-CARs by incorporating single-chain variable fragments from antibodies across different affinity classes.
- Evaluated CD38-CAR T-cell cytotoxicity, proliferation, and cytokine production against CD38-expressing tumor and healthy cells in vitro and in vivo.
Main Results:
- Generated approximately 124 novel CD38 antibodies with affinities reduced by 10- to over 1,000-fold.
- Identified CD38-CAR T-cells derived from antibodies with approximately 1,000-fold reduced affinity.
- These optimized CD38-CAR T-cells demonstrated effective lysis of CD38-positive multiple myeloma cells and spared CD38-positive healthy hematopoietic cells.
Conclusions:
- Systematic affinity modulation of CARs is a viable strategy for enhancing tumor selectivity.
- Reduced-affinity CD38-CAR T-cells provide a promising therapeutic window for targeting multiple myeloma.
- This approach can be broadly applied to develop safer and more effective CAR T-cell therapies for various cancers.
Related Concept Videos
02:57Targeted Cancer Therapies
There are several types of targeted therapies against...
02:50Combination Therapies and Personalized Medicine
The combination of the drug acetazolamide and sulforaphane is a good example of combination therapy to treat cancer. The cells in the interior of a large tumor often die due to the hypoxic and...