Survival outcomes of patients with gastric cancer treated with first-line nivolumab plus chemotherapy based on claudin 18.2 expression.

Background: Claudin 18.2 has emerged as a viable therapeutic target in gastric cancer; however, its clinical relevance in the context of immune checkpoint inhibitor-based chemotherapy is not known. This study aimed to investigate the efficacy of nivolumab plus chemotherapy according to claudin 18.2 expression in patients with gastric cancer.

Methods: This single-center study included patients with advanced gastric cancer who were treated with first-line nivolumab plus chemotherapy (n = 204) or chemotherapy alone (n = 183) whose claudin 18.2 immunohistochemistry results were available. Claudin 18.2 positivity (moderate-to-strong expression in ≥ 75% by the 43-14A clone) was analyzed in terms of efficacy outcomes.

Results: Among patients treated with nivolumab plus chemotherapy, 96 (47.1%) were assessed to have claudin 18.2-positive tumors. Between patients with claudin 18.2-positive and -negative tumors, objective response rate with nivolumab plus chemotherapy was comparable. Progression-free survival (PFS) and overall survival (OS) with nivolumab plus chemotherapy were comparable between those with claudin 18.2-positive and -negative tumors. For both subgroups with PD-L1 combined positive score ≥ 5 and < 5, PFS and OS with nivolumab plus chemotherapy were also comparable between patients with claudin 18.2-positive and -negative tumors. A consistent trend of favorable PFS and OS was observed with nivolumab plus chemotherapy compared to that of chemotherapy alone in both claudin 18.2-positive and -negative subgroups.

Conclusion: The efficacy of nivolumab plus chemotherapy did not vary according to claudin 18.2 positivity. The clinical benefit of nivolumab plus chemotherapy over chemotherapy was consistently observed in claudin 18.2-positive and -negative gastric cancer cases.