PD-L1 potential player in gastric adenocarcinoma

The expression of the programmed death-ligand 1 (PD-L1) is commonly upregulated in patients with gastric adenocarcinoma (GAC) and may play a role in the development of such malignancy, a recent study has found.

“Anti-PD-L1 treatment combined with anti-human epidermal growth factor receptor 2 (HER2) therapy may benefit patients with locally advanced GAC with HER2 overexpression,” the researchers said.

The study involved tumour tissues from 75 GAC patients, in whom PD-L1 and HER2 expression were assessed using immunohistochemical methods. Patients were divided into four groups: HER2 overexpression, PD-L1 positive (group 1); HER2 overexpression, PD-L1 negative (group 2); no HER2 overexpression, PD-L1 positive (group 3); and no HER2 overexpression, PD-L1 negative (group 4).

More than half of the patients provided tumour samples that were positive for PD-L1 (n=43; 57.3 percent). The positivity rates of PD-L1 expression for GAC stages I, II, III, and IV were 11.6 percent, 32.6 percent, 41.9 percent, and 14 percent, respectively. Meanwhile, 13 patients showed HER2 overexpression, 11 of whom were also positive for PD-L1. Spearman correlation analysis found a significant link between both expression profiles (p=0.029).

Over a median follow-up of 48 months, 35 patients died, six developed local recurrence, and 15, 10, and 4 patients saw distant metastases to the liver, lungs, and bones. The respective 3- and 5- year overall survival (OS) rates were 61 percent and 52 percent. Median recurrence-free survival (RFS) was 44 months.

When assessing survival according to PD-L1 and HER2 status, the researchers found that OS and RFS were lower in groups 1 and 2 than in groups 3 and 4. Five-year cumulative survival rate further confirmed that HER2 overexpression seemed to compromise survival, as did PD-L1 positivity.