A Study of SKB264 Versus Investigator's Choice Chemotherapy in Patients With Unresectable Recurrent or Metastatic Triple-Negative Breast Cancer

This is a randomized, open-label, multicenter, Phase 3 study to evaluate the efficacy and safety of SKB264 versus investigator's choice chemotherapy as first-line treatment for patients with unresectable recurrent or metastatic TNBC whose tumors do not express PD-L1 or in patients with PD-L1 positive tumors who received prior anti-PD-1/PD-L1 inhibitor in early setting.

Key Inclusion Criteria:

• Histologically and/or cytologically confirmed TNBC.
• De novo metastatic or relapsed ≥ 6 months post completion of treatment with curative intent.
• No prior systemic anti-cancer therapy for unresectable recurrent or metastatic disease.
• Participants whose tumours are PD-L1-negative, or participants whose tumors are PD-L1 positive and have relapsed after prior anti-PD-1/PD-L1 inhibitor for early-stage disease.
• At least one measurable lesion per RECIST v1.1.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1 with no worsening within 2 weeks prior to randomization.
• A life expectancy of at least 3 months.
• Eligible for the chemotherapy options listed as investigator's choice chemotherapy (paclitaxel, nab-paclitaxel, capecitabine, eribulin, or carboplatin) as assessed by the investigator.
• Adequate organ and bone marrow function.

Key Exclusion Criteria:

• Active second malignancy.
• Uncontrolled or clinical significant cardiovascular disease.
• History of noninfectious pneumonitis/interstitial lung disease (ILD) that required steroids or has current pneumonitis/ILD.
• Active infection requiring systemic therapy within 2 weeks of randomization.
• Active hepatitis B or hepatitis C virus infection.
• Human immunodeficiency virus (HIV) positive or history of acquired immunodeficiency syndrome (AIDS); known active syphilis infection.
• Known hypersensitivity to SKB264 or its excipients.
• Previously received TROP2-targeted therapy or topoisomerase 1 inhibitors.
• Prior treatment with the same investigator's choice chemotherapy (except taxane).
• Pregnant or lactating women.