The Efficacy and Safety of Different Combination Regimens of Inetetamab in First-line Treatment of HER2 Positive Metastatic Breast Cancer

This trial is comparing different drug combinations involving inetetamab (an anti-HER2 antibody) as a first-line treatment for women with HER2-positive breast cancer that has spread or come back. **You may be eligible if...** - You are a woman between 18 and 70 years old - Your breast cancer has been confirmed as HER2-positive by lab testing - Your cancer has come back locally or spread to other organs - You have not previously received first-line anti-HER2 treatment, or completed prior HER2 treatment more than 12 months ago - Your general health is good enough to tolerate treatment (ECOG 0-2) - Your heart function is adequate (LVEF at least 50%) **You may NOT be eligible if...** - Your cancer has spread to the brain and is symptomatic - You have significant heart problems - You have active hepatitis B or C, or HIV - You are pregnant or breastfeeding - You have had a major surgery within the past 4 weeks Talk to your doctor to see if this trial is right for you.