Efficacy of Cytotoxic Agents After Progression on Anti-PD-(L)1 Antibody for Pre-treated Metastatic Gastric Cancer.

BACKGROUND/AIM: The efficacy of treatment using the anti-programmed cell death-1 (anti-PD-1) antibody for metastatic gastric cancer (mGC) has been established previously. Exploratory analyses in various types of tumours suggest that prior exposure to immune checkpoint inhibitors can enhance the efficacy of subsequent cytotoxic chemotherapy (CTx). Our aim is to evaluate the efficacy and safety of CTx for mGC after progression on anti-PD-(ligand) 1 [anti-PD-(L)1] antibody. PATIENTS AND METHODS: We retrospectively evaluated patients with mGC who underwent CTx. The patients received CTx after progression on anti-PD-(L)1 antibody (cohort A) or as a third-line treatment without prior exposure to anti-PD-(L)1 antibody (cohort B). We evaluated: i) clinical characteristics, ii) efficacies, iii) prognoses, and iv) adverse events (AEs). RESULTS: In cohorts A and B, 16 and 68 patients fulfilled the criteria, respectively. In the univariate analysis, the overall response rate was significantly higher in cohort A compared to cohort B (31% vs. 10%, respectively; Odds Ratio:3.96, 95% Confidence Interval:1.06-14.8, p=0.040). The multivariate analysis showed a similar trend. Immune-related AEs did not worsen and were manageable, while new immune-related AEs were not observed. CONCLUSION: CTx after progression on anti-PD-(L)1 antibody demonstrated a favourable efficacy in intensively treated patients with mGC.