Expanded human NK cells armed with CAR uncouple potent anti-tumor activity from off-tumor toxicity against solid tumors

Abstract

Despite the remarkable success of chimeric antigen receptor (CAR)-T cells against hematologic malignancies, severe off-tumor effects have constrained their use against solid tumors. Recently, CAR-engineered natural killer (NK) cells have emerged as an effective and safe alternative. Here, we demonstrate that HER2 CAR-expression in NK cells from healthy donors and patients with breast cancer potently enhances their anti-tumor functions against various HER2-expressing cancer cells, regardless of MHC class I expression. Moreover, HER2 CAR-NK cells exert higher cytotoxicity than donor-matched HER2 CAR-T cells against tumor targets. Importantly, unlike CAR-T cells, HER2 CAR-NK cells do not elicit enhanced cytotoxicity or inflammatory cytokine production against non-malignant human lung epithelial cells with basal HER2 expression. Further, HER2 CAR-NK cells maintain high cytotoxic function in the presence of immunosuppressive factors enriched in solid tumors. These results show that CAR-NK cells may be a highly potent and safe source of immunotherapy in the context of solid tumors.

Targeted integration of EpCAM-specific CAR in human induced pluripotent stem cells and their differentiation into NK cells

“…Thus, our results demonstrated that the regulation of NK cell activity is subject to an array of activating and inhibitory receptors including a transferred CAR. This observation is consistent with a recent report that shows that, unlike HER2 CAR-T cells, HER2 CAR-NK cells do not elicit enhanced cytotoxicity against HER2-positive non-malignant human lung epithelial cells due to the recognition of MHC class I molecules [ 47 ]. Our observation further demonstrated that similar to what happens in NK cells, in iNK cells, the integration of the activating and inhibitory signals could also determine the magnitude of CAR-NK cell reactivity.…”

Challenges and Prospects for Designer T and NK Cells in Glioblastoma Immunotherapy

“…Nevertheless, pre-clinical studies demonstrated HER2-specific T lymphocyte cytotoxicity against GBM stem-like cells that was not evident in HER2 - cells [ 139 ]. In addition, HER2-directed CAR NK cells engineered from healthy donors and breast cancer patients have been shown to selectively kill HER2 + tumour cells while avoiding healthy cells in vitro [ 146 ]. HER2 is also currently the only target used for CAR NK cell therapy in human trials for GBM with the CAR2BRAIN study in Germany (clinical trial ID NCT03383978), as mentioned above.…”

Production of human CAR-NK cells with lentiviral vectors and functional assessment in vitro

“…This protocol may require further optimization for the transduction of cytokine activated NK cells which are typically more difficult to transduce. However, we have also used the protocol to successfully generate CAR-NK cells from the NK-92 human NK cell line as described in Portillo et al. (2021) .…”

“…We also show how to assess CAR-NK cell anti-tumor function in vitro using a flow cytometry-based killing assay. For complete details on the use and execution of this protocol, please refer to Portillo et al. (2021) .…”

“…For complete details on the use and execution of this protocol, please refer to Portillo et al. (2021) .…”