**YMN-136 Vaccine Study** This study is testing a new vaccine called **YMN-136** to see if it's safe and what the best dose is for people with serious liver, bile duct, or pancreatic cancers. These cancers are called **hepatobiliary and pancreatic malignancies**. People in the study must be between 18 and 75 years old and have tried other treatments that didn't work or they couldn't handle. Important terms include **dose escalation trial**, which means trying different amounts of the vaccine to find the safest and most effective dose. Participants need to have a positive **IMP3 expression**, which is a specific marker found in their cancer cells. **ECOG performance status** is a way to measure how well someone can carry out everyday tasks. **Key Points:** - The study will involve frequent visits to check how participants are responding to the vaccine. - Participants should not have had certain treatments or conditions recently, like chemotherapy or infections. - There are specific health criteria participants must meet to join, like certain blood test results and organ function levels. Eligible participants will help researchers learn if the YMN-136 vaccine could be a new option for treating these tough cancers.