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Development of CAR T Cells Expressing a Suicide Gene Plus a Chimeric Antigen Receptor Targeting Signaling
Christina Amatya1, Melissa A Pegues1, Norris Lam1
1National Institutes of Health, National Cancer Institute, Center for Cancer Research, Surgery Branch, Bethesda, MD 20892, USA.
Abstract:
Chimeric antigen receptors (CARs) are fusion proteins that contain antigen-recognition domains and T cell signaling domains. Signaling lymphocytic-activation molecule F7 (SLAMF7) is a promising target for CAR T cell therapies of the plasma cell malignancy multiple myeloma (MM) because SLAMF7 is expressed by MM but not normal nonhematopoietic cells. We designed CARs targeting SLAMF7. We transduced human T cells with anti-SLAMF7 CARs containing either CD28 or 4-1BB costimulatory domains. T cells expressing CD28-containing CARs or 4-1BB-containing CARs recognized SLAMF7 in vitro. SLAMF7-specific cytokine release was higher for T cells expressing CARs with CD28 versus 4-1BB domains. In murine solid tumor and disseminated tumor models, anti-tumor activity of T cells was superior with CD28-containing CARs versus 4-1BB-containing CARs. Because of SLAMF7 expression on some normal leukocytes, especially natural killer cells that control certain viral infections, the inclusion of a suicide gene with an anti-SLAMF7 CAR is prudent. We designed a construct with a CD28-containing anti-SLAMF7 CAR and a suicide gene. The suicide gene encoded a dimerization domain fused to a caspase-9 domain. T cells expressing the anti-SLAMF7 CAR plus suicide-gene construct specifically recognized SLAMF7 in vitro and eliminated tumors from mice. T cells expressing this construct were eliminated on demand by administering the dimerizing agent AP1903 (rimiducid).
Insights
Engineered T-cells targeting SLAMF7 show promise for multiple myeloma treatment. A novel CAR T-cell therapy incorporating a suicide gene offers controllable anti-tumor activity and safety.
Area of Science:
- Immunology
- Oncology
- Biotechnology
Background:
- Chimeric antigen receptors (CARs) are engineered proteins for targeted T-cell therapies.
- Signaling lymphocytic-activation molecule F7 (SLAMF7) is a key target in multiple myeloma (MM).
- SLAMF7 is expressed on MM cells but also on some normal immune cells, posing a safety concern.
Purpose of the Study:
- To design and evaluate CAR T-cells targeting SLAMF7 for multiple myeloma.
- To compare the efficacy of CD28 versus 4-1BB costimulatory domains in anti-SLAMF7 CAR T-cells.
- To develop a safe and controllable CAR T-cell therapy by incorporating a suicide gene.
Main Methods:
- Human T-cells were transduced with anti-SLAMF7 CARs featuring CD28 or 4-1BB costimulatory domains.
- In vitro assays assessed SLAMF7 recognition and cytokine release.
- In vivo studies utilized murine models to evaluate anti-tumor activity.
- A suicide gene construct (caspase-9) was integrated for inducible cell elimination.
Main Results:
- Both CD28- and 4-1BB-based CAR T-cells recognized SLAMF7 in vitro.
- CD28-based CAR T-cells demonstrated superior cytokine release and in vivo anti-tumor activity compared to 4-1BB.
- The CAR T-cell construct with an integrated suicide gene effectively eliminated tumors in mice.
- Administering AP1903 (rimiducid) enabled on-demand elimination of the engineered T-cells.
Conclusions:
- Anti-SLAMF7 CAR T-cells are effective against multiple myeloma models.
- CD28 costimulatory domains enhance CAR T-cell function in this context.
- The inclusion of a suicide gene provides a crucial safety mechanism for SLAMF7-targeted CAR T-cell therapy.
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