A Study of ASP2138 Given Before Surgery, Then Chemotherapy After Surgery, in People With Pancreatic Ductal Cancer

Some people with pancreatic ductal cancer (PDAC) have a protein called Claudin 18.2 (CLDN18.2) in their tumor. ASP2138 is thought to work by binding to CLDN18.2 and a protein on a type of immune cell called a T-cell. The T-cell "tells" the immune system to attack the tumor. This study is for people with resectable PDAC. Resectable means that the tumor can be removed by surgery. In this study, adults with resectable PDAC will receive an ASP2138 injection just below the skin (subcutaneous) 2 weeks before surgery. After surgery, they will be given standard chemotherapy treatments chosen by their study doctor. These include mFOLFIRINOX, gemcitabine with nab-paclitaxel, or gemcitabine with capecitabine. People will receive chemotherapy treatment for up to 6 months, or until their cancer gets worse, they cannot tolerate the chemotherapy, or they or their study doctor thinks they should stop chemotherapy. People will have a final clinic visit about a month after finishing chemotherapy for health checks.