Study of Gemcitabine, Cisplatin, AB680 and AB122 During First Line Treatment of Advanced Biliary Tract Cancers (QUIC)

This is a phase 2 study of gemcitabine, cisplatin, zimberelimab (AB122) and quemliclustat (AB680) in subjects with untreated advanced biliary tract cancers (BTC). The study will include a safety run-in involving 6 study participants. The goal of the safety run-in is to screen for early safety signals of the proposed drug combination. Trial enrollment can continue while full safety assessment is being completed for the first 6 subjects. Participants will receive 4 cycles of combination therapy as described. After 4 cycles (\~6 months), cisplatin will be discontinued, while gemcitabine, zimberelimab (AB122), and quemliclustat (AB680) will be continued. Subjects will be treated until disease progression or development of intolerable toxicities. In total, there will be up to 39 participants on the study.