Effect of ramucirumab plus paclitaxel in advanced gastric cancer according to the status of programmed cell death-ligand 1 (PD-L1) expression.

Background: Ramucirumab, an anti-vascular endothelial growth factor receptor (VEGFR) monoclonal antibody (mAb), inhibits angiogenesis and reduces tumor activity. Programmed cell death-ligand 1 (PD-L1) might act upon VEGFR2 to induce cancer cell angiogenesis and metastasis. Herein, we investigated the efficacy of combining ramucirumab and paclitaxel according to the status of PD-L1 expression in patients with advanced gastric cancer (AGC).

Methods: This analysis included AGC patients who received ramucirumab plus paclitaxel as 2 line therapy between December 1, 2018, and February 28, 2022, at Samsung Medical Center. All patient data analyses included an evaluation of PD-L1 expression using the combined positive score (CPS). We analyzed the efficacy and the survival of patients according to their PD-L1 expression.

Results: We included 117 patients in this analysis, and 80 patients (68.4%) had a PD-L1 CPS of one or more, 37 (31.6%) had five or more, and 19 (16.2%) had ten or more scores. Progression-free survival (PFS) and overall survival (OS) did not differ significantly between patients with a PD-L1 CPS of less than one and one or more {PD-L1 <1% PD-L1 ≥1%; PFS: median 3.6 months [95% confidence interval (CI): 2.4-4.8 months] median 4.1 months (95% CI: 3.5-4.7 months), P=0.93; PD-L1 <1% PD-L1 ≥1%; OS: median 7.0 months (95% CI: 5.4-8.6 months) median 8.1 months (95% CI: 6.4-9.8 months), P=0.32}. PFS and OS did not differ significantly between patients with a PD-L1 CPS of less than 5 and 5 or more [PD-L1 <5% PD-L1 ≥5%; PFS: 3.9 months (95% CI: 3.3-4.5 months) 4.4 months (95% CI: 3.0-5.8 months), P=0.57; OS: 7.4 months (95% CI: 6.5-8.3 months) 10.0 months (95% CI: 1.1-18.9 months), P=0.07]. Interestingly, with a PD-L1 CPS cutoff of 10, PFS and OS did differ significantly [PD-L1 <10% PD-L1 ≥10%; PFS: 3.8 months (95% CI: 3.3-4.3 months) 5.7 months (95% CI: 4.1-7.3 months), P=0.05; OS: 7.2 months (95% CI: 6.5-7.9 months) 18.9 months (95% CI: 6.5-31.3 months), P=0.04].

Conclusions: No biomarkers have been established to predict survival times after ramucirumab plus paclitaxel treatment. This analysis suggests that a PD-L1 CPS cutoff of 10 might be novel a biomarker to predict the survival of AGC patients treated with ramucirumab and paclitaxel.