PD-1 blocking antibodies moonlighting as killers

Area of Science:

• Immunology
• Cancer Therapy
• Preclinical Research

Background:

• Therapeutic antibodies blocking PD-1 have transformed cancer treatment.
• Murine cancer models are vital for evaluating PD-1 inhibitors.
• Antibody isotype and host species can influence blocking antibody efficacy and potential cytotoxicity.

Purpose of the Study:

• To investigate the impact of PD-1 blocking antibodies on T cell populations in preclinical immunotherapy models.
• To highlight the importance of comprehensive antibody characterization in immunotherapy research.

Main Methods:

• Administration of PD-1 blocking antibodies in different in vivo murine models.
• Analysis of T cell populations, including antigen-specific CD8 T cells.
• Evaluation of antibody-mediated effects on T cell activation, proliferation, and survival.

Main Results:

• Certain PD-1 antibodies promoted activation and proliferation of PD-1+ T cells.
• A specific PD-1 antibody led to significant depletion of antigen-specific CD8 T cells in vivo.
• The observed T cell depletion varied depending on the antibody used and experimental model.

Conclusions:

• "Blocking" PD-1 antibodies can induce unintended T cell depletion, affecting immunotherapy study outcomes.
• Comprehensive characterization of PD-1 antibodies is essential to prevent misinterpretation of preclinical immunotherapy data.
• Understanding antibody-mediated effector functions is critical for reliable cancer immunotherapy research.