A Study of YL242 in Subjects With Advanced Solid Tumors

Inclusion Criteria: * Aged ≥18 years. * Eastern Cooperative Oncology Group performance status (ECOG PS) of 0 or 1 * Adequate organ and bone marrow function * Tumor type: Part 1-3: Advanced/unresectable or metastatic solid malignant tumor; Have received at least one prior line of systemic anti-tumor therapy Part 4: locally advanced or metastatic non-sq NSCLC without AGA and HCC; Have not received any systemic anti-tumor therapy; Part 5: mCRC, have received at least one (5a) or one (5b) prior line of systemic anti-tumor therapy Part 6: advanced or metastatic HER2-negative G/GEJ; have received at least one (6a) or one (6b) prior line of systemic anti-tumor therapy Exclusion Criteria: * Be intolerant to prior treatment with a topoisomerase I inhibitor or an ADC that consists of a topoisomerase I inhibitor * Uncontrolled or clinically significant cardiovascular and cerebrovascular diseases * Clinically significant concomitant pulmonary disease * A history of leptomeningeal carcinomatosis or carcinomatous meningitis * Any illness, medical condition, organ system dysfunction, or social situation, including but not limited to mental illness or substance/alcohol abuse, deemed by the investigator to be likely to interfere with a patient's ability to sign informed consent, adversely affect the patient's ability to cooperate and participate in the study, or compromise the interpretation of study results