Overexpression of HIF-1α via small activating RNA enhances CAR-T cell function in hypoxic microenvironments

Area of Science:

• Immunology
• Cancer Biology
• Cell Therapy

Background:

• Chimeric antigen receptor (CAR)-T cell therapy shows promise in blood cancers but struggles with solid tumors.
• The hypoxic tumor microenvironment hinders CAR-T cell effectiveness by promoting T cell exhaustion.

Purpose of the Study:

• To develop a novel strategy to enhance CAR-T cell efficacy in solid tumors by targeting the hypoxia-inducible factor-1α (HIF-1α) pathway.
• To investigate the mechanisms by which HIF-1α overexpression impacts CAR-T cell metabolism and function.

Main Methods:

• Utilized a non-viral piggyBac transposon system to co-deliver CAR constructs and small activating RNA (saRNA) for endogenous HIF-1α overexpression (HIF1A^OE) in CAR-T cells.
• Assessed the anti-tumor activity, infiltration capacity, and metabolic profiles of HIF1A^OE-CAR-T cells under hypoxic conditions using 3D tumor spheroids and metabolomic analyses.
• Evaluated the combination therapy of HIF1A^OE-CAR-T cells with anti-CTLA4 nanobodies in a mouse model.

Main Results:

• HIF1A^OE-CAR-T cells demonstrated enhanced tumoricidal activity and infiltration in hypoxic environments.
• HIF-1α reprogramming of cellular metabolism involved increased aerobic glycolysis (via GLUT1 upregulation) and preserved mitochondrial integrity (via Nrf2/PGC-1α signaling).
• Combination therapy with anti-CTLA4 nanobodies led to synergistic tumor regression and improved infiltration in vivo with no significant toxicity.

Conclusions:

• Endogenous HIF-1α activation is a viable strategy to overcome the immunosuppressive effects of the hypoxic tumor microenvironment for CAR-T cell therapy.
• This approach holds potential for the safe and effective treatment of solid tumors.
• Further development of HIF1A^OE-CAR-T cells could significantly advance solid tumor immunotherapy.