AUTHOR=Tang Ling , Kong Yingjie , Wang Haobing , Zou Ping , Sun Ting , Liu Ying , Zhang Juan , Jin Na , Mao Hanwen , Zhu Xiaojian , Wang Jue , Meng Fankai , You Yong 

TITLE=Demethylating therapy increases cytotoxicity of CD44v6 CAR-T cells against acute myeloid leukemia

JOURNAL=Frontiers in Immunology

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2023.1145441

DOI=10.3389/fimmu.2023.1145441

ISSN=1664-3224

ABSTRACT=CD44v6 chimeric antigen receptor T (CD44v6 CAR-T) cells demonstrate potent anti-tumor ability and safety in acute myeloid leukemia (AML). However, the application of CD44v6 CAR-T is adversely affected by transient fratricide and exhaustion of CD44v6 CAR-T cells due to CD44v6 expression on T cells. The exhaustion and functions of T cells and CD44v6 expression of AML cells are associated with DNA methylation. Hypomethylating agents (HAMs) decitabine (Dec) or azacitidine (Aza) have been widely used to treat AML. Therefore, CD44v6 CAR-T cells and HAMs may have synergy against AML. CD44v6 CAR T cells or AML cells were pretreated with Dec or Aza, and the cytotoxicity of CD44v6 CAR-T cells to AML was detected. Our results revealed that Dec and Aza improved the functions of CD44v6 CAR-T cells through increasing the absolute output of CAR+ cells and persistence, promoting activation and memory phenotype of CD44v6 CAR-T cells, and Dec had a more pronounced effect. Dec and Aza promoted the apoptosis of AML cells, particularly with DNA methyltransferase 3A (DNMT3A) mutation. Dec and Aza also enhanced the CD44v6 CAR-T response to AML by upregulating CD44v6 expression of AML cells regardless of FMS-like tyrosine kinase 3 (FLT3) or DNMT3A mutations. The combination of Dec or Aza pretreated CD44v6 CAR-T with pretreated AML cells demonstrated the most potent anti-tumor ability against AML. These findings demonstrate that Dec or Aza combined with CD44v6 CAR-T is a promising therapy for AML.