Low-dose radiotherapy synergizes with PD-1 blockade to achieve durable survival in advanced NSCLC through antitumor neutrophil programming

The optimal strategy for combining radiotherapy (RT) and immunotherapy remains under intensive investigation. Here we developed TRIDENT (Triple Radio-Immunotherapy-Driven ENhanced Therapy), a novel triple-modality regimen combining immunomodulatory low-dose RT (LDRT) to large tumor(s), immunogenic high-dose RT (HDRT) to small tumor(s), and PD-1 blockade. In our phase I trial of 29 patients with treatment-naïve, PD-L1-positive advanced non-small cell lung cancer (NSCLC), TRIDENT achieved a median overall survival (mOS) of 51.3 months (95% CI, 20.7-not reached), higher than outcomes typically reported with contemporary standard (chemo)immunotherapy. This durable survival signal was corroborated in an independent real-world cohort of 97 patients with advanced lung cancer (mOS: 41.5 months; 95% CI, 26.3-63.7). Mechanistically, TRIDENT elicited neutrophil-dependent, systemic antitumor immunity and induced a distinct population of antitumor TNF-α⁺ neutrophils marked by increased MHC and costimulatory molecule expression. Neutrophil recruitment was driven by the CXCL–CXCR2 axis, and polarization toward an antitumor state was programmed by treatment-induced IFN-γ and GM-CSF. TNF-α⁺ neutrophils enhanced CD8⁺ T-cell function via ICAM-1–LFA-1 interactions, and adoptive transfer confirmed their intrinsic antitumor activity in vivo. Spatial transcriptomics of patient tumor tissues further identified a TNF-α+ neutrophil-effector CD8+ T-cell niche after TRIDENT, providing a stimulatory signal to effector CD8⁺ T cells. In line with these mechanistic findings, clinical biomarker analyses linked neutrophil number with prolonged survival. TRIDENT activates an RT-driven neutrophil-CD8⁺ T-cell axis and promotes survival-associated neutrophil activation. These mechanistic insights, coupled with durable survival in our phase I trial, position TRIDENT as a promising strategy for metastatic NSCLC currently undergoing randomized phase II evaluation. Our study also highlights TNF-α+ neutrophils as a promising therapeutic strategy to enhance antitumor efficacy.