This is a global, multi-center, open-label, Phase I/II first-in-human study of XNW27011 monotherapy as an investigational product (IP) in patients with locally advanced and/or metastatic solid tumors who have failed or are intolerant to standard therapies. XNW27011 is an antibody-drug conjugate (ADC) targeting Claudin 18.2 (CLDN18.2), a transmembrane protein important to tight junctions. The study consists of 2 parts: Part 1 is the dose-escalation phase (Phase I), and Part 2 is the does-expansion phase (Phase II). In phase I part of the study, approximately 42 patients with locally advanced and/or metastatic solid tumors will be enrolled, irrespective of CLDN18.2 expression. However, the most recently available tumor tissue specimen will be collected (if available) for a retrospective CLDN18.2 expression confirmation. In phase II part of the study, only patients with confirmed CLDN18.2 expression by IHC in the central laboratory will be enrolled.The phase II part of the study will consist of the following four groups，Up to three dose cohorts for each patient group are planned currently. Each dose cohort will include approximately 20 patients. Approximately 240 patients evaluable will be enrolled in Phase Ⅱ part of the study.
Phase I (Dose Escalation)：
Patients are willing and able to provide written informed consent or where consent is provided by legally authorized representatives.
Age ≥18 years old when signing the informed consent form.
Patients with a histologically or cytologically-confirmed, locally advanced or metastatic solid tumor, which has failed on standard therapy or is intolerable to available standard therapy, or there is no available standard therapy for the tumor. The advanced solid tumors include but are not limited to gastric and gastroesophageal junction adenocarcinoma, pancreatic adenocarcinoma, esophageal adenocarcinoma, ovarian cancer, lung cancer, colorectal cancer, andbiliary tract cancer.
PHASE I (DOSE ESCALATION)：
Prior severe allergic reaction or intolerance to a monoclonal antibody, including humanized or chimeric antibodies.
Prior severe allergic reaction or intolerance to the Topoisomerase I Inhibitor or Topoisomerase Inhibitor-Based ADC (e.g: Fam-trastuzumab deruxtecan-nxki, Sacituzumab govitecan-hziy, Irinotecan, Topotecan) or any excipient in the XNW27011 formulation.
Acquired or congenital immunodeficiency diseases or organ transplantation.