Lymph node fine-tuning FcγR signaling boosts anti-PD-1 therapy.

Area of Science:

• Immunology
• Oncology
• Pharmacology

Background:

• Anti-PD-1 monoclonal antibody (mAb) therapy enhances anti-tumor T cell responses by promoting new T cell clonotypes.
• Mechanisms driving the mobilization of these T cells into tumors remain unclear.

Purpose of the Study:

• To investigate how anti-PD-1 mAbs influence circulating T cell dynamics and their recruitment into tumor-draining lymph nodes (TDLNs).
• To elucidate the roles of FcγR engagement and type I interferon (IFN) in T cell trafficking during anti-PD-1 therapy.

Main Methods:

• Utilized transgenic mouse models (FcγR-deficient, type I IFN receptor-deficient, FcγR-humanized) to study T cell dynamics.
• Compared Fc-silent anti-PD-1 variants with conventional antibodies and another immune checkpoint inhibitor (anti-TIM-3).
• Evaluated nivolumab effects in human cell-based assays with dynamic imaging.

Main Results:

• Anti-PD-1 mAbs enhance circulating T cell recruitment into TDLNs, expanding the anti-tumor response.
• This T cell influx is mediated by FcγR engagement and type I IFN production, triggering chemokine release.
• Observed similar mechanisms with an anti-TIM-3 inhibitor, indicating a broad role in checkpoint blockade.

Conclusions:

• Revealed a novel role for FcγR engagement in TDLNs during anti-PD-1 therapy.
• FcγR engagement amplifies anti-tumor T cell responses by facilitating T cell recruitment.
• This finding broadens the understanding of immune checkpoint blockade mechanisms.