Real-world efficacy and biomarker of nivolumab for advanced gastric cancer.

Abstract

388 Background: Although nivolumab demonstrated survival benefit and a manageable safety profile in previously-treated advanced gastric cancer in a phase III trial (ATTRACTION-2), the efficacy of nivolumab in real-world and predictive factors of responses to nivolumab for advanced gastric cancer remain unclear. We evaluated the efficacy of nivolumab and compared clinicopathological characteristics with responses to nivolumab and long-term survivals in patients with gastric cancer. Methods: 205 patients with unresectable or recurrent gastric cancer who were treated with nivolumab as 3rd or more line treatment were enrolled from 23 institutions. Tissue specimens were collected in 199 patients. PD-L1 expression of tumor specimens defined as tumor positive score (TPS) and combined positive score (CPS) and mismatch repair (MMR) were analyzed by immunohistochemistry. Tumor responses were assessed according to RECIST version 1.1. Hyper progressive disease (HPD) was defined as ≥two folds increase in tumor growth rate. Results: 138 out of 205 enrolled patients had measurable lesions. Response rate and HPD rate were 16.7% (23/138) and 22.0% (29/132), respectively. Response rate was significantly higher in patients with performance status (PS) 0-1, non-peritoneal diseases, CPS ≥10, and MMR deficient patients. On the other hand, PS 2-3 and liver metastases were predictive factors of HPD. Patients with CPS≥10 and MMR deficiency showed significantly better progression-free (P = 0.005, P = 0.001) and overall survivals (P = 0.005, P = 0.002). TPS showed no significant association with any outcomes. Conclusions: Real-world efficacy of nivolumab was shown in previously-treated advanced gastric cancer. CPS and MMR could be the useful biomarkers for the efficacy of nivolumab treatment as well as PS and metastasis site. Clinical trial information: UMIN000032164.