ESTRO 2024 - Abstract Book

S436

Clinical - Biomarkers

ESTRO 2024

Keywords: mature tertiary lymphoid structure, immunotherapy

93

Digital Poster

LZAP as a novel biomarker signature predicting survival and adjuvant chemotherapeutic benefit

You-Xin Gao, Li-Li Shen, Xiao-Qian Ye

Fujian Medical University Union Hospital, Department of Gastric Surgery, Fuzhou, China

Purpose/Objective:

To examine the clinical significance of LZAP to predict chemotherapeutic responsiveness in gastric cancer.

Material/Methods:

A collection of 188 pairs of tumour tissue microarray specimens from Fujian Medical University were employed for the discovery set, and 310 tumour tissue samples of gastric cancer patients were employed for the internal validation set. Eight-five tumour tissue samples from Qinghai University Hospital were used as the external validation set 1. Transcriptomic and clinical data of 299 gastric cancer patients from TCGA were used as the external validation set 2. LZAP expression, microsatellite instability (MSI) status, and tumour-infiltrating lymphocytes (TIL) were examined with immunohistochemistry. Clinical outcomes of patients were compared with Kaplan-Meier curves and the Cox model.

Results:

In a multi-centre evaluation, increased LZAP indication of better prognosis depends mainly on MSI-L/MSS status or TILhigh. High LZAP expression predicts sensitive therapeutic responsiveness to postoperative adjuvant chemotherapy in gastric cancer. In a stratification analysis based on LZAP combined with TIL or MSI status, patients with LZAPlow TILlow showed no significant difference in prognosis after receiving chemotherapy, whereas patients with LZAPlow TILhigh, LZAPhigh TILlow, and LZAPhigh TILhigh had better responsiveness to chemotherapy. In addition, patients with LZAPhigh MSI-L/MSS status benefitted the most from adjuvant chemotherapy among all patients evaluated.

Conclusion:

LZAP can be used as an effective marker to evaluate individualized chemotherapy regimens in gastric cancer patients dependent on their TIL and MSI status.

Keywords: chemotherapy, TLS, MSI, LAZP