A Study to Select a Dose Regimen (Part A) and to Investigate Overall Survival (Part B) With Nanvuranlat Compared With Physician's Best Choice in Participants Aged 18 Years or Older With Biliary Tract Cancer

This study is designed to 1) select a dose regimen for continued development and 2) evaluate nanvuranlat versus Physicians Best Choice (PBC) (FOLFOX, FOLFIRI, or Best Supportive Care (BSC)) in participants aged 18 years and over with BTC. Participants enrolling in Part A the trial will be randomly assigned to receive 1 of 3 nanvuranlat dose regimens or PBC. In Part B, participants will be randomly assigned to receive nanvuranlat or PBC. Participants will receive treatment every 2 weeks for as long as they do not experience safety issues, or their cancer gets worse, and the study doctor feels they should stop treatment. Health measurements including physical examinations, vital signs, ECGs, and safety laboratory tests will be performed to monitor safety, and tumor imaging will be performed to monitor cancer response to treatment. Other exploratory makers will be measured to better understand how nanvuranlat works.