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A Real-time Potency Assay for Chimeric Antigen Receptor T Cells Targeting Solid and Hematological Cancer Cells
Published on: November 12, 2019
Chimeric PD‑1 receptor redirects primary T cells against childhood solid tumors but not to PD‑1 ligand‑positive
Chansu Shin1, Masaru Imamura1, Yasushi Kasahara1
1Department of Pediatrics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Niigata 951‑8510, Japan.
Abstract:
The clinical application of T cells engineered with chimeric antigen receptors (CARs) for solid tumors is challenging. A major reason for this involves tumor immune evasion mechanisms, including the high expression of immune checkpoint molecules, such as the programmed death 1 (PD‑1) ligands PD‑L1 and PD‑L2. The inducible expression of PD‑L1 in tumors has been observed after CAR‑T‑cell infusion, even in tumors natively not expressing PD‑L1. Furthermore, numerous types of pediatric cancer do not have suitable targets for CAR‑T‑cell therapy. Therefore, the present study aimed to develop novel CAR‑T cells that target PD‑L1 and PD‑L2, and to evaluate their efficacy against pediatric solid tumors. A novel CAR harboring the immunoglobulin V‑set domain of the human PD‑1 receptor as an antigen binding site (PD‑1 CAR‑T) was developed without using a single‑chain variable fragment. PD‑1 CAR‑T cells were successfully manufactured by adding an anti‑PD‑1 antibody, nivolumab, to the ex vivo expansion culture to prevent fratricide during the manufacturing process due to the inducible expression of PD‑L1 in activated human T cells. The expression of PD‑L1 (and PD‑L2 to a lesser extent) was revealed to be highly upregulated in various pediatric solid tumor cells, which displayed no or very low expression initially, on in vitro exposure to interferon‑γ and/or tumor necrosis factor‑α, which are cytokines secreted by tumor‑infiltrating T cells. Furthermore, PD‑1 CAR-T cells exhibited strong cytotoxic activity against pediatric solid tumor cells expressing PD‑L1 and PD‑L2. Conversely, the effect of PD‑1 CAR‑T cells was significantly attenuated against PD‑L1‑positive cells coexpressing CD80, suggesting that the toxicity of PD‑1 CAR‑T cells to normal immune cells, including antigen presenting cells, can be minimized. In conclusion, PD‑1 ligands are promising therapeutic targets for pediatric solid tumors. PD‑1 CAR‑T cells, either alone or in combination with CAR‑T cells with other targets, represent a potential treatment option for solid tumors.
Insights
New chimeric antigen receptor T cells (CAR-T) targeting PD-L1 and PD-L2 show promise for pediatric solid tumors. These PD-1 CAR-T cells effectively kill tumor cells and may overcome immune evasion, offering a potential new therapy.
Area of Science:
- Immunology
- Oncology
- Biotechnology
Background:
- Chimeric antigen receptor T cell (CAR-T) therapy for solid tumors faces challenges due to tumor immune evasion.
- Immune checkpoints like programmed death 1 (PD-1) ligands (PD-L1/PD-L2) are key mechanisms of tumor immune evasion.
- Many pediatric cancers lack suitable targets for current CAR-T cell therapies.
Purpose of the Study:
- To develop novel CAR-T cells targeting PD-L1 and PD-L2 for pediatric solid tumors.
- To evaluate the efficacy of these novel CAR-T cells against pediatric solid tumors.
- To investigate strategies to mitigate potential off-tumor toxicity.
Main Methods:
- Development of a novel CAR construct (PD-1 CAR-T) using the PD-1 receptor's V-set domain.
- Manufacturing of PD-1 CAR-T cells with addition of nivolumab to prevent T cell fratricide.
- In vitro assessment of PD-L1/PD-L2 expression on pediatric solid tumor cells upon cytokine stimulation.
- Evaluation of PD-1 CAR-T cell cytotoxic activity against tumor cells and assessment of co-expression effects (e.g., CD80).
Main Results:
- PD-1 CAR-T cells were successfully manufactured.
- PD-L1 and PD-L2 expression were significantly upregulated on pediatric solid tumor cells after interferon-γ and/or tumor necrosis factor-α exposure.
- PD-1 CAR-T cells demonstrated potent cytotoxic activity against PD-L1/PD-L2 expressing tumor cells.
- Co-expression of CD80 on PD-L1-positive cells attenuated PD-1 CAR-T cell activity, suggesting reduced toxicity to antigen-presenting cells.
Conclusions:
- PD-1 ligands (PD-L1/PD-L2) are promising therapeutic targets for pediatric solid tumors.
- PD-1 CAR-T cells represent a potential treatment strategy for pediatric solid tumors, possibly in combination with other CAR-T therapies.
- Targeting PD-1 ligands offers a novel approach to overcome tumor immune evasion in pediatric cancers.
