This study is testing a new treatment for people with advanced pancreatic cancer that cannot be removed by surgery. The treatment combines a type of radiation called intensity-modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) with two drugs: envafolimab (an injection) and capecitabine (a pill). These drugs help the radiation work better. To join, patients need to be 18-90 years old, have this specific type of cancer, and meet other health criteria. The study is only for those who haven't had certain treatments before. Participants will receive weekly injections of envafolimab and take capecitabine pills for two weeks followed by one week off. This cycle repeats until the treatment stops working or the patient can't tolerate it.

• This study requires regular hospital visits for treatment and monitoring.
• Participants need to be willing to follow the treatment plan and attend follow-ups.
• Participants should not have any active infections or other serious health conditions.