Longitudinal Analysis of Peripheral Blood CD4+ T-Cell Profiles and Clinical Outcomes in Metastatic Non-Small-Cell Lung Cancer Patients Following Bronchoscopic Cryotherapy and Pembrolizumab-Based Therapy

Bronchoscopic cryotherapy is routinely used for endobronchial tumor debulking, but may also exert systemic immunologic effects that could interact with immune checkpoint blockade. We investigated peripheral blood T-cell dynamics following bronchoscopic cryotherapy and subsequent pembrolizumab-based first-line therapy in metastatic non-small-cell lung cancer (NSCLC). In this prospective, randomized, controlled single-center study, patients with metastatic NSCLC were randomized into treatment groups of bronchoscopic cryotherapy performed 7 (±1) days before standard-of-care pembrolizumab (with or without platinum-based chemotherapy) or to standard-of-care therapy alone. Peripheral blood mononuclear cells were analyzed by flow cytometry at baseline, week 3, and week 6. Radiologic response was assessed using RECIST 1.1. Progression-free survival (PFS) and overall survival (OS) were evaluated using the Kaplan–Meier test and Cox regression. Flow cytometry was performed on 34 cryotherapy and 42 control patients. The cryotherapy group demonstrated a decrease in circulating CD4+ T cells (p = 0.002) and an increase in circulating CD8+ T cells (p = 0.013) by week 6. CD25+FOXP3+CD4+ Tregs decreased from baseline to week 3 (p = 0.024) and remained reduced through week 6. Overall response rate was higher in the cryotherapy group (41.2% vs. 16.7%; p = 0.022), while PFS and OS were numerically longer, although not statistically different (median PFS 9.5 vs. 5.3 months; median OS 17.6 vs. 14.8 months). The decrease in Tregs at week 3 was observed to predict better PFS. In patients with metastatic NSCLC receiving first-line pembrolizumab with or without chemotherapy, the addition of bronchoscopic cryotherapy was associated with a detectable peripheral immune remodeling and a higher objective response rate, whereas PFS and OS were numerically longer but not statistically different.