To increase the specificity and safety of CAR-NK cells, Fei and Rong et al. engineered anti-CD19 or -CD33 NK-CARs to co-express an anti-HLA-DR inhibitory CAR (iCAR) that can effectively suppress NK cell activation against HLA-DR-expressing cells and selectively target HLA-DR-negative cells. CAR-NK cell inhibition correlated with iCAR and HLA-DR densities, however, surrounding cells expressing HLA-DR did not alter their target selectivity. In xenograft models, dual CAR-NK cells showed similar killing compared to CAR-NK cells against HLA-DR-CD19+ CML and HLA-DR-CD33+ AML cells, without eliminating HLA-DR+ cells.
Contributed by Shishir Pant
ABSTRACT: Chimeric antigen receptor natural killer (CAR-NK) cells have remarkable cytotoxicity against hematologic malignancies; however, they may also attack normal cells sharing the target antigen. Since human leukocyte antigen DR (HLA-DR) is reportedly lost or downregulated in a substantial proportion of hematologic malignancies, presumably a mechanism to escape immune surveillance, we hypothesize that the anti-cancer specificity of CAR-NK cells can be enhanced by activating them against cancer antigens while inhibiting them against HLA-DR. Here, we report the development of an anti-HLA-DR inhibitory CAR (iCAR) that can effectively suppress NK cell activation against HLA-DR-expressing cells. We show that dual CAR-NK cells, which co-express the anti-CD19 or CD33 activating CAR and the anti-HLA-DR iCAR, can preferentially target HLA-DR-negative cells over HLA-DR-positive cells in vitro. We find that the HLA-DR-mediated inhibition is positively correlated with both iCAR and HLA-DR densities. We also find that HLA-DR-expressing surrounding cells do not affect the target selectivity of dual CAR-NK cells. Finally, we confirm that HLA-DR-positive cells are resistant to dual CAR-NK cell-mediated killing in a xenograft mouse model. Our approach holds great promise for enhancing CAR-NK and CAR-T cell specificity against malignancies with HLA-DR loss.
Author Info: (1) Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089, USA. (2) Department of Pharmacology and Ph
Author Info: (1) Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089, USA. (2) Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089, USA. (3) Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089, USA. (4) Cancer and Blood Disease Institute, Division of Hematology-Oncology, Children's Hospital Los Angeles, Los Angeles, CA 90027, USA; Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA. (5) Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089, USA; Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA. Electronic address: jianminx@usc.edu.
