The study consists of two phases. Phase 1b and Phase 2. Phase 1b aims to evaluate the safety, tolerability, and preliminary efficacy of SYS6010 as a monotherapy and in combination with SYH2051, and to determine the recommended Phase 2 dose (RP2D) for subsequent Phase 2 studies. Phase 2 aims to assess the efficacy and safety of SYS6010 monotherapy or in combination with SYH2051 compared to investigator-selected chemotherapy in patients with EGFR-expressing, unresectable locally advanced or metastatic advanced breast cancer.
1. Age ≥ 18 years. 2. Phase 1b/Phase 2: Breast cancer (no tumor type restriction during the combination dose escalation phase).
1. Active central nervous system (CNS) metastases or carcinomatous meningitis. Patients with treated and stable brain metastases are eligible for inclusion.