Immune-related adverse events in various organs caused by immune checkpoint inhibitors

Area of Science:

• Oncology
• Immunology
• Dermatology

Background:

• Cancer immunotherapies utilize immune checkpoint inhibitors (ICIs) targeting programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), and cytotoxic T-lymphocyte antigen 4 (CTLA-4).
• ICIs activate the immune system but can lead to immune-related adverse events (irAEs), frequently manifesting as cutaneous conditions mimicking autoimmune disorders.
• irAEs involve ICI-activated CD8+ cytotoxic T cells, with some cases linked to B cell activation and pathogenic antibodies.

Purpose of the Study:

• To elucidate the complex mechanisms underlying immune-related adverse events (irAEs) induced by cancer immunotherapies.
• To differentiate the mechanisms of irAEs caused by CTLA-4 blockade versus PD-1/PD-L1 blockade.
• To provide insights for improved management of irAEs, enhancing patient outcomes and quality of life.

Main Methods:

• Review of current literature on cancer immunotherapies and immune checkpoint inhibitors (ICIs).
• Analysis of the immunological pathways involved in irAEs, focusing on T cell and B cell responses.
• Comparison of the distinct mechanisms triggered by CTLA-4 and PD-1/PD-L1 inhibition.

Main Results:

• CTLA-4 blockade primarily activates T cells and inhibits regulatory T cells (Tregs).
• Anti-PD-1/PD-L1 therapies induce more complex irAE mechanisms involving PD-1 interactions with PD-L1 and PD-L2.
• PD-L1's role is dominant in Th1/Th17 immunity, while PD-L2 primarily influences Th2 immunity.

Conclusions:

• Understanding the specific mechanisms of ICI-induced irAEs is crucial for effective clinical management.
• Differentiating irAE pathways based on the targeted immune checkpoint (CTLA-4 vs. PD-1/PD-L1) is essential.
• Further research into irAE mechanisms will improve patient care and quality of life in cancer immunotherapy.