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

## TL;DR

This study identifies biomarkers like CD8+ lymphocytes and TLS density that predict response and survival in esophageal cancer patients treated with nivolumab.

## Contribution

The study introduces CD8/Foxp3 and CD8/CCR8 ratios and TLS density as novel predictive biomarkers for PD-1 blockade efficacy in ESCC.

## Key findings

- CD8+ lymphocyte counts and TLS density in surgical specimens correlate with clinical response to nivolumab.
- CD8/Foxp3 ratio and TLS density are independent prognostic factors for overall survival in surgical specimens.
- In endoscopic biopsies, CD8/CCR8 ratio is an independent prognostic parameter for nivolumab response.

## Abstract

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.

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.

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/mm2 vs. 0.10/mm2, 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/mm2 vs. 124 cells/mm2, P = 0.0344), CCR8+ lymphocyte count (62.6 cells/mm2 vs. 140 cells/mm2, 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.

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.

The online version contains supplementary material available at 10.1007/s10388-025-01120-z.