Macrophage NLRP3 activation and IL-1β release drive osimertinib-induced antitumor immunity.

Background: Despite the clinical efficacy of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in non-small cell lung cancer (NSCLC), patient outcomes vary even among those with identical EGFR mutations. This study investigates whether osimertinib, a third-generation EGFR-TKI, activates the nucleotide-binding oligomerization domain-like receptor protein-3 (NLRP3) inflammasome in macrophages to drive antitumor immunity and explores its mechanistic basis.

Methods: Using bone marrow-derived macrophages from wild-type and gene-deficient mice, human peripheral blood mononuclear cells, and a Lewis lung cancer murine model, we assessed osimertinib-induced NLRP3 inflammasome activation, interleukin (IL)-1β secretion, pyroptosis, and tumor microenvironment (TME) remodeling. Mechanistic studies evaluated lysosomal dysfunction, calcium overload, mitochondrial damage, and reactive oxygen species (ROS) production. Clinical correlations were analyzed in patients with NSCLC treated with EGFR-TKIs.

Results: Osimertinib triggered NLRP3 inflammasome activation in macrophages via lysosomal dysfunction-induced calcium overload, leading to mitochondrial damage and ROS production, which acted as damage-associated molecular patterns to activate NLRP3. This process promoted IL-1β release, pyroptosis, and CD8⁺ T-cell activation while suppressing regulatory T cells in the TME. In murine models, osimertinib's antitumor effects were abrogated by NLRP3 inhibition (MCC950) and enhanced by recombinant IL-1β (rIL-1β) co-administration (p<0.01). Clinically, high NLRP3 and IL-1β expression in tumor-associated macrophages (TAMs) correlated with prolonged progression-free survival (p<0.01) and overall survival (p<0.01) in EGFR-TKI-treated patients with NSCLC.

Conclusions: Osimertinib exerts off-target immunomodulatory effects by activating the tumor-extrinsic NLRP3 inflammasome, linking mitochondrial-lysosomal crosstalk to antitumor immunity. NLRP3 and IL-1β in TAMs emerge as predictive biomarkers for EGFR-TKI efficacy, while rIL-1β combination therapy represents a novel strategy to enhance clinical outcomes.