ABSTRACT
PURPOSE: Stereotactic body radiation therapy (SBRT) versus surgery for operable early-stage non-small cell lung cancer (ES-NSCLC) remains highly debated. Herein, we used spatial proteomics to identify whether any molecular biomarker(s) associate with the efficacy of either modality, in efforts to optimize treatment selection between surgery and SBRT for this population. METHODS AND MATERIALS: We evaluated biopsy tissue samples from 44 patients with ES-NSCLC treated with first-line SBRT (cohort 1) by GeoMx Digital Spatial Profiling (DSP) with a panel of 70 proteins in 5 spatial molecular compartments: tumor (panCK+), leukocyte (CD45+), lymphocyte (CD3+), macrophage (CD68+), and stroma (α-SMA+). To validate the findings in cohort 1, biopsy samples from 52 patients with ES-NSCLC who received SBRT (cohort 2) and 62 patients with ES-NSCLC who underwent surgery (cohort 3) were collected and analyzed by multiplex immunofluorescence (mIF). RESULTS: In cohort 1, higher CD44 expression in the lymphocyte compartment was associated with poorer recurrence-free survival (RFS) (DSP: P < .001; mIF: P < .001) and higher recurrence rate (DSP: P = .001; mIF: P = .004). mIF data from cohort 2 validated these findings (P < .05 for all). From cohort 3, higher lymphocyte CD44 predicted higher RFS after surgery (P = .003). Intermodality comparisons demonstrated that SBRT was associated with significantly higher RFS over surgery in CD44-low patients (P < .001), but surgery was superior to SBRT in CD44-high cases (P = .016). CONCLUSIONS: Lymphocyte CD44 may not only be a predictor of SBRT efficacy in this population but also an important biomarker (pending validation by large prospective data) that could better sharpen selection for SBRT versus surgery in ES-NSCLC.
