A Study to Assess Adverse Events and Change in Disease Activity With Treatment Combinations With Telisotuzumab Adizutecan in Adults Participants With Pancreatobiliary Cancers

Cancer is a condition where cells in a specific part of the body grow and reproduce uncontrollably. The pancreas is a gland behind the stomach that produces a digestive fluid that is emptied into the intestines through tube shaped ducts. Pancreatic cancer often starts in these ducts. The goal of this study is to evaluate the safety and efficacy of telisotuzumab adizutecan in combination with gemcitabine and nab-paclitaxel in adult participants with pancreatobiliary cancers. Telisotuzumab adizutecan is an investigational drug being developed for the treatment of pancreatobiliary cancers. In Substudy 1, participants will be randomized into two groups. One group will receive different doses of telisotuzumab adizutecan with gemcitabine. The other group will receive standard of care (SOC) - gemcitabine and nab-paclitaxel. Approximately 168 participants will be enrolled in this study in approximately 50 sites worldwide. Substudy 1 includes a dose escalation stage and a dose optimization stage. In the dose escalation stage, participants will receive escalating doses of Intravenous (IV) telisotuzumab adizutecan + Gemcitabine. In the dose optimization stage, participants will receive 1 of 2 doses of IV telisotuzumab adizutecan with Gemcitabine or SOC. The study will run for a duration of approximately 3 years. There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the study at an approved institution (hospital or clinic). The effect of the treatment will be frequently checked by medical assessments, blood tests, questionnaires and side effects.