To evaluate the safety and tolerability of CT0494BCP following infusion in participants with advanced gastric/esophagogastric junction adenocarcinoma (G/GEJA) To evaluate preliminary efficacy of CT0494BCP To evaluate the cellular metabolism kinetics of CT0494BCP The investigational drug in this study is CT0494BCP cells, including CT0494 cells and CT7095 cells. Dose escalation will be performed according to the Bayesian optimal interval (BOIN) design principle (refer to the dose escalation principle in Section 4.1 Study Design Description and the flow chart of BOIN design in Figure 2 for details) and dose expansion. In the dose escalation phase, CT0494 cells were tentatively assigned to 3 escalating doses of 3.0 × 108, 4.5 × 108 and 6.0 × 108, respectively, and CT7095 cells were tentatively assigned to 2 escalating doses of 1.5 × 108 and 3.0 × 108, respectively. If the exploratory dose is not identified as a possible recommended dose (RD), a possible RD may be explored by escalating to a higher dose or tapering to a lower dose at the discretion of the investigator and sponsor in consultation. Dose groups, number of subjects per dose group, and other escalation or de-escalation decisions may be adjusted during the study based on available data.