Targeting PARP11 to avert immunosuppression and improve CAR T therapy in solid tumors

Area of Science:

• Immunology
• Oncology
• Molecular Biology

Background:

• The tumor microenvironment (TME) promotes immune evasion and therapy resistance in solid tumors.
• Key TME factors, including regulatory T cells and adenosine, suppress anti-tumor immunity.
• Downregulation of type I interferon receptor (IFNAR1) on CD8+ cytotoxic T lymphocytes (CTLs) impairs anti-tumor responses.

Purpose of the Study:

• To investigate the role of poly-ADP ribose polymerase-11 (PARP11) in regulating the immunosuppressive TME.
• To determine if targeting PARP11 can enhance anti-tumor immunity and immunotherapy efficacy.

Main Methods:

• Analysis of PARP11 induction in intratumoral CTLs.
• Genetic or pharmacologic inactivation of PARP11 in preclinical models.
• Assessment of IFNAR1 expression on CTLs.
• Evaluation of CTL tumoricidal activity and tumor growth inhibition.
• Testing the efficacy of PARP11-inactivated chimeric antigen receptor (CAR) T cells.

Main Results:

• PARP11 is induced in intratumoral CTLs and mediates the downregulation of IFNAR1.
• PARP11 ablation prevents IFNAR1 loss, enhances CTL activity, and inhibits tumor growth in an IFNAR1-dependent manner.
• Inactivation of PARP11 significantly improves the therapeutic efficacy of CAR T cells against solid tumors.

Conclusions:

• PARP11 is a critical regulator of the immunosuppressive TME and CTL function.
• Targeting PARP11 represents a promising strategy to overcome immune evasion and enhance the effectiveness of cancer immunotherapies, including CAR T cell therapy.