Exosomal miRNA-148b/301a/423 cluster predicts pneumonitis risk in NSCLC with concurrent radiotherapy with immunotherapy via PTPN14-YAP signaling: a retrospective cohort study.

BACKGROUND: Radiotherapy (RT) combined with Immune checkpoint inhibitors (ICIs) significantly improve outcomes in non-small cell lung cancer (NSCLC), yet this combination amplifies treatment-related pneumonitis risk. The real-world incidence, predictive biomarkers, and underlying pathogenesis of RT-ICI-associated pneumonitis remain inadequately defined. METHODS: We conducted a retrospective cohort study using electronic health records from 21,671 NSCLC patients treated with thoracic RT, categorized into RT-ICI (n=8,744) and RT-nonICI (n=12,927) groups after 1:1 propensity score matching. Pneumonitis was diagnosed via clinical/imaging criteria and infection exclusion. Incidence of pneumonitis was evaluated using propensity score-matched analysis, Kaplan-Meier curves, and Cox regression models. Subgroup analyses were performed across demographic and clinical variables. Serum exosomes from 20 patients underwent miRNA sequencing. LASSO regression for biomarker modeling, single-cell RNA-seq analysis and single-sample gene set enrichment analysis for function enrichment, then validated in vitro. RESULTS: The incidence of pneumonitis was significantly higher in the RT-ICI group (28.9%) compared to the RT-nonICI group (10.0%) (hazard ratio [HR]=2.86; 95% confidence interval [CI], 2.43-3.29; P<0.001). This elevated risk persisted across age, sex, BMI, comorbidities, and autoimmune status. We identified a serum exosomal miRNA cluster (miR-148b-3p, miR-301a-3p, miR-423-3p) predictive of pneumonitis and poor survival. These miRNAs directly co-target PTPN14, and crosstalk with fibrosis via TNF signal at the single-cell level. Then we validated the miRNA cluster suppressed PTPN14, activating YAP signal to promote EMT in pulmonary epithelial cell lines. CONCLUSIONS: RT-ICI therapy significantly increases pneumonitis risk in NSCLC, especially in autoimmune comorbidities. A serum exosomal miRNA cluster (miR-148b-3p/301a-3p/423-3p) enables early pneumonitis prediction and prognosis assessment, offering novel targets for prevention and monitoring.