Serum extracellular vesicle–enriched miR-21 and miR-155 and acute toxicity during chemoradiotherapy for stage III NSCLC: a prospective pilot study

Purpose This prospective pilot study investigated treatment-related changes in miR-21 and miR-155 expression in a serum fraction enriched for extracellular vesicles (EVs) and explored their associations with acute toxicity and thoracic dosimetric parameters in patients with stage III non-small cell lung cancer (NSCLC) undergoing definitive chemoradiotherapy (CRT). Materials and methods Twenty-one patients with stage III NSCLC were prospectively enrolled. Serum samples were collected before CRT and after the final treatment fraction. miR-21 and miR-155 expression in the extracellular-vesicle-enriched fraction was measured using quantitative real-time polymerase chain reaction (qRT-PCR) and normalized to miR-16. Fold change was calculated as 2^ − ΔΔCt. Adverse events were graded according to the Common Terminology Criteria for Adverse Events, version 5.0, during CRT and at 1 and 3 months after treatment. Results Paired miR-21 measurements were available for all 21 patients. Median miR-21 expression decreased from 2.365 before CRT to − 2.060 after CRT on the − ΔCt scale (Hodges–Lehmann estimate of the paired difference, − 4.783; 95% confidence interval [CI], − 6.430 to − 2.920; p < 0.001). Paired miR-155 measurements were available for 20 patients. Median miR-155 expression decreased numerically from 2.895 to − 0.373, but the change was not statistically significant (Hodges–Lehmann estimate, − 1.219; 95% CI, − 3.377 to 1.167; p = 0.294). Three patients developed grade 3 radiation esophagitis, and two developed grade 3 radiation pneumonitis; because of these small event numbers, toxicity subgroup findings were considered descriptive. Post-treatment miR-155 expression was nominally positively correlated with lung V5 ( n = 21; Spearman’s ρ = 0.493; 95% CI, 0.110–0.753; p = 0.023) and lung V20 ( n = 21; ρ = 0.578; 95% CI, 0.166–0.817; p = 0.006). However, neither association remained statistically significant after false-discovery-rate correction (q = 0.347 and q = 0.182, respectively). Conclusion CRT was associated with a significant reduction in miR-21 expression in the serum EV-enriched fraction, whereas the numerical reduction in miR-155 expression was not statistically significant. The nominal associations between post-treatment miR-155 expression and lung V5/V20 did not remain significant after correction for multiple comparisons. Trial registration ClinicalTrials.gov identifier NCT06015815; retrospectively registered on August 29, 2023.