Citraconate preserves T cell stemness and antitumor immunity

Area of Science:

• Immunology
• Metabolic pathways
• Cancer research

Background:

• Tumor microenvironment metabolic changes impair CD8 T cell stemness and function.
• Understanding T cell metabolic regulation is crucial for improving cancer immunotherapy.

Purpose of the Study:

• Identify metabolic factors sustaining T cell stemness.
• Investigate citraconate's role in T cell function and anti-tumor immunity.

Main Methods:

• Metabolite analysis in CD8 T cells under chronic stimulation/hypoxia.
• Assessing citraconate supplementation effects on T cell stemness, ferroptosis, and anti-tumor activity.
• Elucidating the molecular mechanism involving PDE1, cAMP, PKA, and ALOX5.
• Correlating ALOX5/PDE1A expression with clinical responses to immune checkpoint blockade (ICB).

Main Results:

• Citraconate is depleted in exhausted CD8 T cells.
• Citraconate supplementation preserves T cell stemness, reduces ferroptosis, and enhances anti-tumor immunity.
• Citraconate maintains cAMP levels by inhibiting PDE1A/C, preserving mitochondrial function and activating PKA signaling.
• PKA activation represses ALOX5, decreasing lipid peroxidation.
• Low ALOX5 or PDE1A expression correlates with less T cell exhaustion and better ICB response.

Conclusions:

• The PDE1-cAMP-ALOX5 metabolic axis is critical for T cell function in the tumor microenvironment.
• Citraconate acts as a key regulator, preserving T cell stemness and effector functions.
• Targeting this axis, particularly with citraconate, represents a promising strategy to enhance cancer immunotherapy efficacy.