Novel, Stable, and Well-Secreted Single-Chain Fc Forms of Programmed Death-1 Immune Checkpoint Inhibitor Efficiently...

Area of Science:

• Immunology
• Gene Therapy
• Oncology

Background:

• Immune checkpoint inhibitors (ICIs) like anti-PD-1 antibodies treat cancer but benefit limited patients and cause adverse events.
• Systemic ICI administration poses challenges, necessitating localized or alternative therapeutic strategies.

Purpose of the Study:

• To investigate recombinant adenoviral vectors encoding various secreted Programmed Death 1 (sPD-1) variants for improved cancer immunotherapy.
• To evaluate the efficacy of different sPD-1 constructs in blocking PD-1:PD-L1 interactions and signaling.

Main Methods:

• Screening of eight sPD-1 variants and generation of adenoviruses with top four constructs.
• Analysis of sPD-1 secretion via immunoblotting and ligand binding (PD-L1/PD-L2) using pull-down assays and ELISA.
• Assessment of PD-1:PD-L1 interaction inhibition using cell-based signaling bioassays and coculture models.

Main Results:

• Fc-fusion sPD-1 variants demonstrated superior sPD-1 yields and ligand binding efficiency.
• Single-chain Fc-fusion sPD-1 constructs were most potent, effectively inhibiting PD-1-mediated signaling in T cells.
• In vitro assays confirmed the ability of specific sPD-1 variants to block immune checkpoint pathways.

Conclusions:

• Engineered sPD-1 variants delivered via adenoviral vectors show significant potential for cancer immunotherapy.
• Stable, well-secreted sPD-1 constructs offer a promising avenue for site-specific immune gene therapy.
• This study provides a foundation for developing localized immunotherapies with potentially reduced systemic toxicity.