Peripheral CD8+ T Cell Dynamics and Clinical Outcomes in Metastatic Non-Small Cell Lung Cancer Following Bronchoscopic Cryotherapy and Pembrolizumab-Based Therapy.

Background

Bronchoscopic cryotherapy may enhance anti-tumor immunity and improve the effect of immune checkpoint blockade, but CD8+ T cell dynamics after cryotherapy combined with pembrolizumab-based therapy in metastatic non-small cell lung cancer (NSCLC) remain insufficiently characterized.

Methods

In this prospective, exploratory, randomized, controlled, single-center study, metastatic NSCLC patients were assigned to bronchoscopic cryotherapy performed 7 ± 1 days before first-line pembrolizumab-based therapy or to standard treatment alone. Peripheral blood mononuclear cells were analyzed by flow cytometry at baseline, week 3, and week 6. CD8+ T cell subsets defined by CD45RO, CD28, granzyme B (GzB), IFNγ, Ki-67, and PD-1 were evaluated in relation to treatment group, radiologic response, progression-free survival (PFS), and overall survival (OS).

Results

Flow cytometry was performed in 76 patients, including 34 in the cryotherapy group and 42 in the control group. Cryotherapy was associated with a treatment-specific increase in circulating GzB+ CD8+ T cells by week 6. In contrast, Ki-67+ CD8+ and GzB+Ki-67+ cells increased in both treatment groups, suggesting that early peripheral CD8+ proliferation was largely shared across pembrolizumab-based therapy. Radiologic responders demonstrated more sustained proliferative CD8+ dynamics, most consistently reflected by increased CD28+ Ki-67+ cells. In exploratory landmark survival analyses, a higher week-3-to-baseline GzB+ Ki-67+ CD8+ ratio showed a hypothesis-generating association with longer PFS and OS.

Conclusions

In metastatic NSCLC patients receiving first-line pembrolizumab-based therapy, the addition of bronchoscopic cryotherapy was associated with peripheral CD8+ T cell remodeling toward enhanced cytotoxic activity. Proliferative CD8+ T cell changes were associated with radiologic response and better survival. These findings support bronchoscopic cryotherapy as a potential immune-modulating adjunct and warrant validation in larger studies.