Development of Multi-Engineered iPSC-Derived CAR-NK Cells for the Treatment of B-Cell Malignancies

Induced-pluripotent stem cells (iPSCs) can be differentiated into various somatic cells, including different immune cell types. We have engineered iPSC-derived NK cells with multiple features to generate therapeutic candidates designed to eliminate cancer cells while avoiding recognition by the host immune system. The unlimited replication capacity of iPSCs facilitates the engineering of several genetic modifications without the risk of driving cells to exhaustion as in the case of cell products derived from fully differentiated immune cells. Once all edits are completed, our cells are single-cell cloned and each clone is genetically characterized to select clones without off-target insertions or deletions. Following the genetic characterization, selected clones are differentiated and tested in vitro and in vivo to identify the final clinical candidate. The use of a single-cell iPSC clone enables the generation of a master cell bank producing a highly uniform cell product that can be made available off-the-shelf at any clinical site.

CNTY-101 is an iPSC-derived CAR-NK clinical candidate for the treatment of B-cell malignancies. It incorporates six gene edits designed to improve persistence and functionality as well as safety. These modifications include edits to reduce graft rejection due to alloreactivity, the expression of a homeostatic cytokine to improve functionality and persistence, the introduction of a chimeric antigen receptor (CAR) targeting CD19 to mediate tumor cell engagement and killing, as well a safety switch to eliminate the cells, if ever necessary. To prevent rejection by the patient's CD8 T cells, the beta-2-microbulin (ß2M) gene was disrupted with simultaneous insertion of a transgene encoding the HLA-E protein tethered with ß2M and a peptide. HLA-E was introduced to prevent NK cell cytotoxicity against the engineered cells, which lack HLA-I. For resistance to CD4 T cell-mediated allogenic immune rejection, the class II major histocompatibility complex transactivator (CIITA) gene was disrupted with simultaneous insertion of a transgene encoding the extra-cellular and transmembrane domains of EGFR, and the NK cell growth factor IL-15. EGFR provides an elimination tag that can be engaged by clinically approved anti-EGFR antibodies, such as cetuximab. Finally, the CAR transgene targeting the CD19 antigen was inserted into the AAVS1 safe harbor locus.

Our data indicates that CNTY-101 iNK cells have strong antitumor activity against lymphoma cell lines both in vitro and in vivo. In vitro, CNTY-101 eliminates lymphoma cell lines through multiple rounds of killing without reaching exhaustion. Clones expressing higher levels of IL-15 tend to have better persistence and functionality, with some clones showing robust cytotoxicity for over fifteen rounds of serial killing. In vivo, the clones that demonstrated better in vitro serial killing tend to mediate the best anti-tumor activity in lymphoma xenograft models. Upon 3 weekly doses, the most active candidate clone demonstrated significant tumor growth inhibition after administration of fresh (91 % tumor growth inhibition) or cryopreserved cells (76 % tumor growth inhibition).

The efficacy of the EGFR-safety switch was also investigated both in vitro and in vivo. In vitro, addition of cetuximab to co-cultures of IL-2-activated PBMC and cells mediated antibody-dependent cellular cytotoxicity (ADCC) in a concentration-dependent fashion, with an EC50 of 2 ng/ml. In vivo, there was a 96% reduction in the number of iPSC-derived CAR-NK cells in the lungs and a 95% reduction in the number of CAR-NK cells in the blood of mice that received cetuximab versus PBS-treated mice.

In summary, CNTY-101 is a novel, multi-engineered, allogeneic CAR-iNK product candidate for the treatment of B-cell malignancies. It includes multiple immune evasion features to prevent recognition by the patient's immune system and expression of IL-15 to facilitate persistence and functionality. We have initiated GMP manufacturing of CNTY-101 and plan to enter clinical trials in 2022.