PD-L1 CAR effector cells induce self-amplifying cytotoxic effects against target cells. Issue 1 (25th January 2022)

• Record Type: Journal Article
• Authors: Bajor, Malgorzata; Graczyk-Jarzynka, Agnieszka; Marhelava, Katsiaryna; Burdzinska, Anna; Muchowicz, Angelika; Goral, Agnieszka; Zhylko, Andriy; Soroczynska, Karolina; Retecki, Kuba; Krawczyk, Marta; Klopotowska, Marta; Pilch, Zofia; Paczek, Leszek; Malmberg, Karl-Johan; Wälchli, Sébastien; Winiarska, Magdalena; Zagozdzon, Radoslaw
• Is Part Of: Journal for immunotherapy of cancer. Volume 10:Issue 1(2022)
• Publication Date: 2022-01-25
• Subjects: receptors -- chimeric antigen -- T lymphocytes -- killer cells -- natural; Cancer -- Immunotherapy -- Periodicals; Cancer -- Immunological aspects -- Periodicals; Tumors -- Immunological aspects -- Periodicals; Immunotherapy -- Periodicals; 616.99406105
• DOI: 10.1136/jitc-2021-002500
• Languages: English
• ISSNs: 2051-1426

Abstract

Abstract : Background: Immune checkpoint inhibitors and chimeric antigen receptor (CAR)-based therapies have transformed cancer treatment. Recently, combining these approaches into a strategy of PD-L1-targeted CAR has been proposed to target PD-L1 high tumors. Our study provides new information on the efficacy of such an approach against PD-L1 low targets. Methods: New atezolizumab-based PD-L1-targeted CAR was generated and introduced into T, NK, or NK-92 cells. Breast cancer MDA-MB-231 and MCF-7 cell lines or non-malignant cells (HEK293T, HMEC, MCF-10A, or BM-MSC) were used as targets to assess the reactivity or cytotoxic activity of the PD-L1–CAR-bearing immune effector cells. Stimulation with IFNγ or with supernatants from activated CAR T cells were used to induce upregulation of PD-L1 molecule expression on the target cells. HER2–CAR T cells were used for combination with PD-L1–CAR T cells against MCF-7 cells. Results: PD-L1–CAR effector cells responded vigorously with degranulation and cytokine production to PD-L1 high MDA-MB-231 cells, but not to PD-L1 low MCF-7 cells. However, in long-term killing assays, both MDA-MB-231 and MCF-7 cells were eliminated by the PD-L1–CAR cells, although with a delay in the case of PD-L1 low MCF-7 cells. Notably, the coculture of MCF-7 cells with activated PD-L1–CAR cells led to bystander induction of PD-L1 expression on MCF-7 cells and to the unique self-amplifying effect of the PD-L1–CAR cells. Accordingly, PD-L1–CAR T cells were active not only against MDA-MD-231 and MCF-7-PD-L1 but also against MCF-7-pLVX cells in tumor xenograft models. Importantly, we have also observed potent cytotoxic effects of PD-L1–CAR cells against non-malignant MCF-10A, HMEC, and BM-MSC cells, but not against HEK293T cells that initially did not express PD-L1 and were unresponsive to the stimulation . Finally, we have observed that HER-2–CAR T cells stimulate PD-L1 expression on MCF-7 cells and therefore accelerate the functionality of PD-L1–CAR T cells when used in combination. Conclusions: In summary, our studies show that CAR-effector cells trigger the expression of PD-L1 on target cells, which in case of PD-L1–CAR results in the unique self-amplification phenomenon. This self-amplifying effect could be responsible for the enhanced cytotoxicity of PD-L1–CAR T cells against both malignant and non-malignant cells and implies extensive caution in introducing PD-L1–CAR strategy into clinical studies.