KN026 in Combination With Chemotherapy in HER2 Positive Gastric Cancer Subjects Who Have Failed First-line Therapy

This study is testing whether a drug called KN026 — which targets a protein called HER2 on cancer cells — combined with chemotherapy is effective for people with HER2-positive stomach or gastroesophageal junction cancer whose cancer grew during or after their first treatment. **You may be eligible if:** - You are at least 18 years old - You have confirmed HER2-positive advanced stomach or gastroesophageal junction cancer - Your cancer progressed during or after a first-line treatment that included trastuzumab and chemotherapy - Your performance status is adequate (ECOG 0–1) - Your life expectancy is at least 3 months - Your blood counts and organ function are within acceptable ranges **You may NOT be eligible if:** - You have not tried any prior treatment for advanced gastric cancer - Your organ function is significantly impaired - You have other serious active conditions that would make treatment unsafe Talk to your doctor to see if this trial is right for you.