Exploring predictive biomarkers of efficacy and survival with nivolumab treatment for unresectable/recurrent esophageal squamous cell carcinoma.

BACKGROUND

Programmed cell death protein-1 (PD-1) blockade has improved survival for patients with esophageal squamous cell carcinoma (ESCC), but response rates are low. Biomarkers to predict who will benefit from PD-1 blockade are urgently needed.

METHODS

This multicenter study involved 250 patients with recurrent/unresectable advanced ESCC receiving nivolumab as second- or later-line therapy. We assessed tumor-infiltrating T lymphocytes (TILs) and tertiary lymphoid structure (TLS) density using immunohistochemistry and hematoxylin/eosin staining in surgical specimens and pre-nivolumab endoscopic biopsies.

RESULTS

In surgical specimens, clinical response (vs. non-response) to nivolumab correlated significantly with CD8 lymphocyte count (160 vs. 95.2 cells/field, P = 0.0494), CD8/Foxp3 ratio (6.52 vs. 2.72, P = 0.0053), and TLS density (0.21/mm vs. 0.10/mm, P = 0.0005). In terms of overall survival, multivariate analysis identified CD8/Foxp3 ratio (hazard ratio [HR] = 1.83, P = 0.0050) and TLS density (HR = 1.67, P = 0.0171 as independent prognostic parameters in surgical specimens. Similarly, in endoscopic biopsies, clinical response (vs. non-response) to nivolumab correlated significantly with CD8 counts (254 cells/mm vs. 124 cells/mm, P = 0.0344), CCR8 lymphocyte count (62.6 cells/mm vs. 140 cells/mm, P = 0.0355), CD8/Foxp3 ratio (2.09 vs. 0.89, P = 0.040), and CD8/CCR8 ratio (2.34 vs. 0.89, P = 0.0020). Multivariate analysis also identified CD8/CCR8 ratio in endoscopic biopsies (HR = 1.66, P = 0.0313) as an independent prognostic parameter.

CONCLUSIONS

CD8 and CCR8 cell counts, CD8/Foxp3 and CD8/CCR8 ratios, and TLS density may be predictive biomarkers of therapeutic efficacy and survival with PD-1 blockade for ESCC.