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.