Low-dose Radiotherapy Combined With Chemotherapy and AK112 as Second-line Treatment in Patients With Advanced G/GEJ Cancer

This study is testing whether combining low-dose radiation with chemotherapy and AK112 (an immunotherapy drug that targets two proteins cancer uses to hide from the immune system) works better than current second-line options for people with advanced stomach or gastroesophageal junction cancer that stopped responding to first-line treatment. **You may be eligible if...** - You are between 18 and 75 years old - You have advanced gastric (stomach) or gastroesophageal junction adenocarcinoma confirmed by tissue test - Your cancer has stopped responding to first-line (standard initial) treatment - You have at least one measurable tumor on a scan - Your expected survival is at least 6 months - Your organ function meets required minimums **You may NOT be eligible if...** - You have not yet tried first-line treatment - You do not have measurable disease - Your performance status or organ function does not meet requirements - You are pregnant or not using contraception Talk to your doctor to see if this trial is right for you.