A Study of BL-B01D1, SI-B003 and BL-B01D1+SI-B003 in Patients With Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma and Other Solid Tumors

This study is testing new drug combinations — including BL-B01D1 (an antibody-drug conjugate) and SI-B003 (an anti-PD-L1 antibody) — in patients with head and neck squamous cell carcinoma or other solid tumors that have returned or spread and no longer respond to standard treatments. **You may be eligible if:** - You are between 18 and 75 years old - You have confirmed recurrent or metastatic head and neck squamous cell carcinoma (not nasopharyngeal) - Your cancer has progressed after at least one prior treatment, or you have not previously received systemic treatment in the metastatic setting (depending on which group you join) - You have at least one measurable tumor on imaging - You are in good general health (ECOG 0–1) **You may NOT be eligible if:** - You had certain cancer treatments within the past 4 weeks - You have an active, uncontrolled infection - You are pregnant or nursing - Your organ function does not meet the required levels Talk to your doctor to see if this trial is right for you.