A First-in-Human Study of YL217 in Patients With Advanced Solid Tumors

Inclusion Criteria: * Informed of the study before the start of the study and voluntarily sign their name and date in the ICF * Able and willing to comply with protocol visits and procedures * Age≥ 18 years * ECOG PS of 0 or 1 * Pathologically confirmed diagnosis of an advanced solid tumor. For CRC cohorts: : Histologically or cytologically documented locally advanced unresectable or metastatic colorectal carcinoma that is not eligible for curative surgery and/or definitive chemoradiotherapy * Adequate organ and bone marrow function. * Have at least 1 extracranial measurable tumor lesion. * Adequate archival formalin-fixed paraffin embedded （FFPE） tissue from prior biopsy. Exclusion Criteria: * Prior treatment with an agent targeting CDH17 * Prior discontinuation of a topoisomerase I inhibitor due to treatment-related toxicities. * Have received an ADC consisting of a topoisomerase I inhibitor. * Concurrent enrollment in another clinical study, unless it is an observational clinical study. * Inadequate washout period for prior anticancer treatment before the first dose of study drug * Undergone major surgery within 4 weeks before the first dose of study drug or expect major surgery during the study, minor procedures (e.g., core needle biopsy, superficial biopsy) within 7 days before the first dose of study drug. * Received long term systemic steroids or other immunosuppressive therapy within 2 weeks before the first dose of study drug. * Received any live vaccine within 4 weeks before the first dose of study drug or intend to receive a live vaccine during the study. * Diagnosis or evidence of spinal cord compression or leptomeningeal carcinomatosis. * Uncontrolled or clinically significant cardiovascular and cerebrovascular diseases. * A history of non-infectious interstitial lung disease (ILD)/pneumonitis that requires steroids, current active ILD/pneumonitis. * Have clinically severe pulmonary compromise resulting from intercurrent pulmonary illnesses. * Uncontrolled third-space fluid that requires repeated drainage. * Digestive system disease that may cause bleeding, perforation, jaundice, fistula, GI obstruction within 6 months prior to the first dose of study drug administration or have active inflammatory bowel disease. * An active tuberculosis based on medical history. * Known human immunodeficiency virus (HIV) infection. * Active hepatitis C infection.