A Clinical Trial to Test if the Investigational Drug BNT329 is Safe and Potentially Beneficial for People With Advanced Solid Tumors Known to Express the Tumor Marker CA19-9

Key Inclusion Criteria All participants and parts: * Have an ECOG PS of 0 to 1 * Have measurable disease per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1), except for ovarian cancer where participants will be evaluated according to Gynecologic Cancer InterGroup criteria. * Have a life expectancy of ≥3 months in the opinion of the investigator. * Have adequate organ, coagulation, and hematologic function as defined in the protocol. Parts A, B, and C: * Have a histologically confirmed advanced/metastatic tumor type that is known to express CA19-9: PDAC, carcinoma of the bile ducts, invasive urothelial carcinoma of the bladder and urinary tract, colorectal adenocarcinoma, adenocarcinoma of the esophagogastric junction, endometrial carcinoma, and epithelial ovarian cancer (including adenocarcinoma of the fallopian tube and peritoneal epithelial cancer \[except mesothelioma\]). * Have no available standard of care therapy likely to confer clinical benefit in the opinion of the investigator. Participants must have received all available standard therapies, including targeted therapies based on mutation status (per guidelines from the Food and Drug Administration, American Society of Clinical Oncology, European Society for Medical Oncology, or local guidelines used at the site), and failed at least first-line standard of care therapy prior to enrollment. Part D: * Have a histologically confirmed diagnosis of PDAC. * Have received at least one prior syst…