When Binding Is Not Blockade: Interpreting IgG4+ T Cells After PD-1 Therapy.

IgG4 positivity on circulating T cells after PD-1 therapy may indicate residual antibody binding rather than sustained functional PD-1 blockade. During sequential ramucirumab plus docetaxel plus G-CSF treatment, peripheral IgG4+ T-cell dynamics may also be influenced by redistribution and treatment-related confounders, limiting direct inference about effective intratumoral antitumor immunity.