Acod1 Expression in Cancer Cells Promotes Immune Evasion through the Generation of Inhibitory Peptides

Area of Science:

• Immunology
• Cancer Biology
• Metabolic pathways

Background:

• Immune checkpoint blockade (ICB) therapy, particularly targeting PD-1, is a cornerstone of cancer treatment.
• Efficacy of ICB is often limited by immunosuppressive factors within the tumor microenvironment (TME).
• Certain cancer types exhibit resistance to ICB, necessitating strategies to overcome TME-mediated immunosuppression.

Approach:

• Investigated the role of itaconate (ITA) and its producing enzyme, aconitate decarboxylase (Acod1), in mediating resistance to anti-PD-1 (αPD-1) therapy.
• Assessed the impact of Acod1 levels on cancer cell resistance and TME immunosuppression.
• Explored the mechanistic link between Acod1 activity, cancer cell secreted factors, and CD8+ T cell proliferation.

Key Points:

• αPD-1-resistant cancer cells exhibit elevated levels of Acod1, leading to increased itaconate production.
• Reducing Acod1 expression in resistant cancer cells restores sensitivity to αPD-1 therapy.
• High Acod1 levels in cancer cells suppress naïve CD8+ T cell proliferation via secreted inhibitory peptides, not itaconate itself.

Conclusions:

• Acod1 plays a critical role in mediating cancer cell resistance to αPD-1 immunotherapy.
• Targeting Acod1 activity presents a potential therapeutic strategy to enhance the efficacy of ICB in resistant tumors.
• Further research into Acod1 inhibition could lead to novel approaches for overcoming TME-induced immunosuppression in cancer therapy.