Priming Leukemia with 5-Azacytidine Enhances CAR T Cell Therapy.

Area of Science:

• Immunology
• Oncology
• Pharmacology

Background:

• Chimeric antigen receptor (CAR) T cell therapy shows promise for B cell acute lymphoblastic leukemia (B-ALL).
• Therapeutic success is often limited by CAR T cell expansion and persistence issues, leading to patient relapse.

Purpose of the Study:

• To investigate the efficacy of 5-azacytidine (AZA) as a priming agent to enhance CAR T cell therapy for B-ALL.
• To elucidate the mechanisms by which AZA improves CAR T cell therapy outcomes.

Main Methods:

• Utilized patient-derived xenograft (PDX) mouse models of CD19+ B-ALL.
• Administered AZA prior to CAR T cell infusion.
• Performed transcriptome analysis and co-culture experiments to assess CAR T cell function and target cell interactions.

Main Results:

• AZA priming delayed leukemia growth and significantly enhanced CAR T cell expansion, effector function, and target cell killing.
• AZA treatment upregulated immune pathways in leukemia cells, including TNFSF4 (OX40L), a co-stimulatory ligand.
• Increased OX40L expression on leukemia cells correlated with enhanced CAR T cell activity and susceptibility to CAR T cell-mediated killing.

Conclusions:

• Epigenetic priming with AZA sensitizes leukemia cells to CAR T cell therapy.
• AZA treatment activates OX40L/OX40 co-stimulatory signaling, promoting CAR T cell efficacy.
• Clinical consideration of AZA as a pre-treatment for CAR T cell therapy in B-ALL is warranted.