Demethylating therapy increases anti-CD123 CAR T cell cytotoxicity against acute myeloid leukemia

Abstract

Successful treatment of acute myeloid leukemia (AML) with chimeric antigen receptor (CAR) T cells is hampered by toxicity on normal hematopoietic progenitor cells and low CAR T cell persistence. Here, we develop third-generation anti-CD123 CAR T cells with a humanized CSL362-based ScFv and a CD28-OX40-CD3ζ intracellular signaling domain. This CAR demonstrates anti-AML activity without affecting the healthy hematopoietic system, or causing epithelial tissue damage in a xenograft model. CD123 expression on leukemia cells increases upon 5′-Azacitidine (AZA) treatment. AZA treatment of leukemia-bearing mice causes an increase in CTLA-4negative anti-CD123 CAR T cell numbers following infusion. Functionally, the CTLA-4negative anti-CD123 CAR T cells exhibit superior cytotoxicity against AML cells, accompanied by higher TNFα production and enhanced downstream phosphorylation of key T cell activation molecules. Our findings indicate that AZA increases the immunogenicity of AML cells, enhancing recognition and elimination of malignant cells by highly efficient CTLA-4negative anti-CD123 CAR T cells.

Donor T cell DNMT3a regulates alloreactivity in mouse models of hematopoietic stem cell transplantation

“…Additionally, KO T cells had alterations in epigenetically regulated exhaustion programs, which may have contributed to both enhanced GVHD and augmented antitumor responses. The enhanced GVT activity noted in our experimental model is in accordance with recently published findings of enhanced chimeric antigen receptor (CAR) T cell efficacy after DNA methylation inhibition, either through Dnmt3a deletion or pharmacologically (73,74). Our approach has uncovered multiple…”

Challenges and Advances in Chimeric Antigen Receptor Therapy for Acute Myeloid Leukemia

“…Histone deacetylase inhibitors enhanced natural killer group 2 member D (NKG2D) ligand expression on in vitro AML lines resulting in robust NKG2D-specific CAR activity [65]. Hypomethylating agents (HMAs) such as azacytidine have been shown to up-regulate CD123 expression in xenograft models [66]. Decitabine increased CD19 and enhanced the cytotoxic effect of CD19-specific CAR T-cells in patients with r/r B-ALL [67], but has not yet been tested in combination with AML CARs in clinical trials.…”

“…Out of all AML CAR targets, CD123 currently has the most ongoing clinical trials including universal CD123 CARs, bispecific CARs, and CARs with safety switches (Table 1). Anti-CD123 CAR T-cells have successfully eliminated leukemic blasts in multiple pre-clinical studies [66,100,101]. In the first clinical trial of six patients with r/r AML, CD123 CAR T-cells brought 3/6 to CR, 66% of which underwent subsequent allogeneic SCT [102].…”

Combination strategies to optimize the efficacy of chimeric antigen receptor T cell therapy in haematological malignancies

“…A clinical trial of DAC-primed tandem CD19/CD20 CAR T cells for R/R B-NHL is ongoing (NCT04697940). Azacitidine (AZA), another FDA-approved DNMTi, can increase the antigen density of CD70 or CD123 in AML, potentiating CAR T cell targeting (132,133). Existing data are mainly based on tumours pretreated with AZA, and no attempt to directly expose CAR T cells to AZA has been made because there is a concern that AZA promotes Tregs (134).…”