Abstract 1537: CD70 knockout: A novel approach to augment CAR-T cell function

Abstract CD70 and its ligand, CD27, have been described as both activating and suppressing for different cell types including B and T cells. There has been speculation that the CD70/CD27 axis can act in a checkpoint or co-stimulatory manner in certain immuno-oncology settings. Knockout (KO) of CD70 function scored highly in a CRISPR/Cas9 screen of candidate genes for enhanced T cell activity. Deletion of other checkpoint candidates such as PD1, TIM3, LAG3 and TIGIT scored much lower than CD70, both alone and in combination with each other. T cells with CD70 KO showed resistance to exhaustion upon repeated stimulation in culture. CAR-T cells with CD70 KO similarly showed exhaustion resistance, as well as a reduction in apoptosis, increased proliferation, and improved target cell lysis upon sequential rechallenges. CTX130 is an investigational allogeneic CAR-T therapy currently being studied in patients with CD70-expressing tumors, including clear cell renal cell carcinoma and B and T cell malignancies. CTX130 contains KOs of TRAC to avoid GvHD, B2M to protect the product from patient T cells, and CD70 for enhanced CAR-T performance. Comparing CTX130 with and without CD70 KOs shows that CAR-T cells with CD70 KO have increased potency, enhanced ability to withstand multiple tumor challenges in vivo, and increased resistance to overexpression of PDL1 on target cells. Interestingly, while CD70 surface expression may be extremely low or undetectable after manufacturing of CD70-targeted CAR-T cells without CD70 KO, the beneficial properties outlined here are only achievable when the CD70 gene is genetically knocked out. In summary, KO of CD70 confers benefit to CAR-T cells that far exceeds KO of other checkpoint related genes, and this benefit was present regardless of the antigen being targeted. CD70 KO is included in the CTX130 investigational allogeneic CAR-T therapy currently in clinical trials. Citation Format: Mary-Lee Dequeant, Jason Sagert, Demetri Kalaitzidis, Hui Yu, Ashley Porras, Brigid McEwan, Zinkal Padalia, Paul Tetteh, Thao Nguyen, Andrew Dunn, Sarah Spencer, Nicolette Lee, Henia Dar, Daniel Henderson, Sushant Karnik, Pooja Keerthipati, Jonathan A. Terrett. CD70 knockout: A novel approach to augment CAR-T cell function [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1537.