Granzyme B PET Imaging Reveals Lgmn + Macrophage‐Mediated Immune Evasion and Guides Immunotherapy in EGFR‐TKI‐Resistant NSCLC

ABSTRACT Determining optimal therapies for EGFR‐mutant NSCLC after tyrosine kinase inhibitor (TKI) resistance remains challenging. Immune checkpoint inhibitors (ICIs) show limited efficacy, but some patients regain immunotherapy sensitivity post‐TKI. Non‐invasive monitoring to identify responders and understand persistent immune tolerance is needed. In this study, we prospectively evaluated a novel granzyme B‐targeted PET radiotracer, 68 Ga‐GZB, in a clinical cohort of NSCLC patients. 68 Ga‐GZB PET/CT accurately visualized early immune responses and stratified patients likely to benefit from immunotherapy. In preclinical models of acquired EGFR‐TKI resistance, we tracked dynamic immune reactivity via 68 Ga‐GZB PET/CT. Single‐cell transcriptomics and functional validation identified Lgmn + macrophages as a highly immunosuppressive subset driving persistent immunotherapy tolerance. Mechanistically, Lgmn + macrophages secrete extracellular vesicles (EVs) that deliver Lgmn directly into CD8 + T cells. Internalized Lgmn recruits the E3 ubiquitin ligase Chip, initiating the ubiquitination and proteasomal degradation of the glycolytic enzyme Eno1. This cascade severely impairs CD8 + T cell glycolysis, ultimately leading to CD8 + T cell exhaustion. Furthermore, we demonstrate that targeting of Lgmn synergizes with PD‐1 blockade to reactivate anti‐tumor immunity in TKI‐resistant models. Thus, 68 Ga‐GZB PET/CT provides a non‐invasive platform to stratify immunotherapy responses, and targeting Lgmn represents a novel combination strategy for EGFR‐TKI‐resistant NSCLC.