To Evaluate the Safety and Tolerability of Study Drug as a Third-line and Beyond Therapy for Recurrent or Metastatic Gastric Cancer

Inclusion Criteria: * Patients with recurrent or metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma who have progressed after second-line therapy. * Those with Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 * Those with at least one measurable lesion in accordance with RECIST 1.1 Exclusion Criteria: * Patients with a confirmed specific medical history or past surgical history * Patients who meet specific criteria regarding prior treatment * Patients with a history of specific drug administration * Patients with specific comorbidities. * Patients who have undergone major surgery within 4 weeks prior to screening or are expected to require major surgery during the clinical trial are excluded. (However, those who have had minor surgeries * Patients with symptoms at the time of screening, who have not received treatment, or who have rapidly progressing central nervous system (CNS) metastases. * Patients with mental disorders or altered mental status/consciousness (AMS) that impair their ability to understand this clinical trial for informed consent. * Pregnant or Lactating Women * Subjects with a history of severe allergic anaphylactic reactions to the investigational product and/or its components, or who have contraindications to the administration of the investigational product and/or irinotecan * Patients considered unsuitable for this clinical trial by the investigator.