Primary Endpoint of this Study:

To compare Progression-Free Survival (PFS) (as assessed by a Blinded Independent Review Committee [BIRC] based on Response Evaluation Criteria in Solid Tumors [RECIST v1.1]) between JSKN016 and Treatment of Physician's Choice (TPC) in participants with unresectable locally advanced, recurrent, or metastatic triple-negative breast cancer (TNBC).

To compare Overall Survival (OS) between JSKN016 and TPC in the treatment of unresectable locally advanced, recurrent, or metastatic TNBC.

Inclusion Criteria:

• Voluntarily sign the Informed Consent Form (ICF).
• Age ≥ 18 years and ≤ 75 years at the time of signing the ICF, male or female.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Life expectancy ≥ 3 months.
• Histologically and/or cytologically confirmed diagnosis of Triple-Negative Breast Cancer (TNBC) based on pathology reports from the most recent biopsy or other pathological specimens.
• Failure of at least 2 prior lines of systemic chemotherapy.
• At least one measurable extracranial lesion per Response Evaluation Criteria in Solid -Tumors (RECIST) v1.1.
• Agree to provide a tumor tissue specimen.
• Adequate organ and bone marrow function.
• Recovery from prior treatment-related toxicities to ≤ Grade 1 per National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) v5.0, or as specified in the protocol for eligibility.
• Assessed by the investigator as suitable to receive one of the following: eribulin, capecitabine, gemcitabine, vinorelbine, or sacituzumab govitecan.
• Female participants of childbearing potential must have a negative serum/urine pregnancy test within 7 days prior to randomization and agree to contraception during the trial.

Exclusion Criteria:

• Prior treatment with a topoisomerase I inhibitor-based antibody-drug conjugate (ADC), with the exception of TROP2-targeted ADCs.
• Diagnosis of another malignancy within 5 years prior to randomization, excluding curatively treated basal cell carcinoma of the skin, squamous cell carcinoma of the skin, papillary thyroid carcinoma, cervical carcinoma in situ, and other carcinomas in situ.
• Presence of cerebrovascular or cardiovascular diseases or risk factors.
• Inadequate washout from prior therapies prior to randomization.
• Presence of active central nervous system (CNS) metastases without prior local treatment; presence of metastases or compression of the brainstem, meninges, or spinal cord; or history of carcinomatous meningitis.
• Presence of severe or uncontrolled concomitant diseases that may affect safety or compliance.
• Tumor invasion of adjacent vital organs or blood vessels (such as the heart, esophagus, superior vena cava, etc.) or risk of developing an esophagotracheal fistula or esophagopleural fistula.
• Active hepatitis B; active hepatitis C.
• Positive test for human immunodeficiency virus (HIV) or history of acquired immunodeficiency syndrome (AIDS); known active syphilis infection; known active tuberculosis infection.
• History of allogeneic bone marrow or organ transplantation.
• History of significant ophthalmic diseases.
• History of interstitial lung disease (ILD) or non-infectious pneumonitis requiring steroid treatment.