Copper Chelate Targeting Externalized Phosphatidylserine Inhibits PD-L1 Expression and Enhances Cancer Immunotherapy

Area of Science:

• Immunology
• Oncology
• Materials Science

Background:

• PD-1/PD-L1 immune checkpoint inhibitors offer limited clinical response, with resistance observed in many patients.
• Externalized phosphatidylserine (PS) on cancer cells contributes to immune suppression and resistance to PD-L1 blockade therapies.

Purpose of the Study:

• To develop a novel strategy targeting externalized PS to overcome resistance in cancer immunotherapy.
• To investigate the efficacy of a terpyridine-Cu complex with a farnesol tail in enhancing anti-tumor immune responses.

Main Methods:

• A copper chelate (terpyridine-Cu complex with farnesol tail) was synthesized to target externalized PS on cancer cells.
• The compound's effects on dendritic cell maturation, T-cell proliferation, tumor infiltration, and PD-L1 expression were evaluated.
• Tumor eradication and immunological memory were assessed in mouse models of colorectal and melanoma cancers.

Main Results:

• The PS-targeting copper chelate promoted dendritic cell maturation and effector T-cell responses.
• This approach significantly inhibited PD-L1 expression and amplified T-cell-mediated immunity.
• Over 70% of mice with colorectal and melanoma tumors showed complete eradication and developed immunological memory.

Conclusions:

• Targeting externalized PS with a novel copper chelate represents a promising antibody-independent strategy for cancer immunotherapy.
• This approach can overcome limitations of current checkpoint blockade therapies by enhancing anti-tumor immune responses.
• The developed compound effectively induces immunological memory and achieves significant tumor eradication in preclinical models.