Genome editing of PD-L1 mediated by nucleobase-modified polyamidoamine for cancer immunotherapy

Area of Science:

• Immunology
• Nanotechnology
• Gene Editing

Background:

• Immune checkpoint blockade targeting programmed death protein-1 (PD-1) and its ligand (PD-L1) is a key cancer immunotherapy strategy.
• Current methods like siRNA or antibodies provide temporary blockade of the PD-1/PD-L1 pathway, limiting long-term efficacy.

Purpose of the Study:

• To develop a permanent gene-editing strategy to disrupt the PD-L1 gene for enhanced anti-tumor immune response.
• To evaluate a novel nano-delivery system for delivering CRISPR/Cas9 gene editing components to cancer cells.

Main Methods:

• Development of a nucleobase-modified polyamidoamine (PAMAM) derivative (AP-PAMAM) as a nano-carrier.
• Delivery of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated nuclease 9 (Cas9) plasmid into melanoma B16F10 cells via AP-PAMAM.
• Assessment of PD-L1 gene disruption, immune cell activation, and anti-tumor effects following nanoparticle administration.

Main Results:

• The AP-PAMAM nano-delivery system successfully delivered CRISPR/Cas9 plasmids, leading to permanent disruption of the PD-L1 gene in cancer cells.
• Efficient endosomal escape of the CRISPR/Cas9 plasmid was achieved, inhibiting PD-L1 expression.
• Intravenous injection of nanoparticles activated CD8+ T cells, promoted cytokine secretion, and enhanced tumor cell killing.

Conclusions:

• This nano-delivery system provides a permanent solution for blocking the PD-1/PD-L1 pathway through gene editing.
• The developed system demonstrates significant potential for advancing tumor immunotherapy by reactivating anti-tumor immune responses.