This is a phase I/II multicenter study to evaluate the safety and efficacy of JSKN033 in Chinese subjects with unresectable locally advanced/metastatic solid tumors.

Inclusion Criteria:

1. Be able to understand informed consent form, voluntarily participate and sign informed consent form.
2. Age ≥18 year (at the time consent is obtained), male or female.
3. Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.
4. Has a Life expectancy ≥3 months.
5. Has a pathologically documented advanced/unresectable or metastatic solid malignant tumor that is refractory to or intolerable with standard treatment.
6. Has at least 1 measurable lesion at baseline according to RECIST 1.1 criteria.
7. Must have adequate organ function prior to the start of JSKN033.
8. Negative urine/serum pregnancy test for females of childbearing potential who are sexually active with a non-sterilized male partner.

Exclusion Criteria:

1. Has clinically active brain metastases.
2. Previously received any other investigational drug within 28 days prior to enrollment.
3. Previously received local palliative treatment within 14 days prior to enrollment.
4. Previously received major surgeries within 28 days prior to enrollment.
5. Need to receive continuous administration of corticosteroids or immunosuppressants for 7 days within 14 days prior to enrollment.
6. Previously received live vaccine within 28 days prior to enrollment.
7. Previously received antibody conjugate drug with topoisomerase I inhibitor.
8. Has a history of other primary malignant tumors within 5 years prior to enrollment.
9. Has uncontrolled comorbidities as specified by the protocol.
10. Has a history of interstitial pneumonia/lung disease requiring systemic hormonal therapy, or suspected interstitial pneumonia/lung disease that cannot be ruled out by imaging during screening period.
11. Subjects with uncontrolled large serous cavity effusion or moderate to large serous cavity effusion requiring repeated drainage (recurrent within 2 weeks after intervention) such as pleural effusion, pericardial effusion, ascites, etc.
12. Toxicities of previous antitumor therapy did not resolve to grade 1 defined by CTCAE v5.0.
13. Has a history of life-threatening anaphylaxis or known hypersensitivity to any component or excipient to the study drug.
14. Has a history of allogeneic bone marrow or organ transplantation.
15. Pregnant or breastfeeding female patients.
16. Other conditions that the investigator considers unsuitable to participate in this clinical trial, including but not limited to psychiatric disorders, alcoholism or drug abuse, etc.