Durvalumab With Chemotherapy as First Line Treatment in Patients With Advanced Biliary Tract Cancers (aBTCs)

Participants will receive 1500 mg every 3 weeks, or every 4 weeks (in combination with chemotherapy every 3 weeks, or every 2 weeks, respectively) from cycle 1 to cycle 8 of chemotherapy. Upon completion, participants will receive 1500 mg every 4 weeks (as monotherapy)

Gemcitabine monotherapy as background gemcitabine-based chemotherapy every 3 weeks (i.e., 8 cycles of durvalumab)

Gemcitabine plus cisplatin as background gemcitabine-based chemotherapy every 3 weeks (i.e., 8 cycles of durvalumab) for WHO/ECOG PS 2 participants only

Gemcitabine + oxaliplatin as background gemcitabine-based chemotherapy every 3 weeks (i.e., 8 cycles of durvalumab)

Gemcitabine + carboplatin as background gemcitabine-based chemotherapy every 3 weeks (i.e., 8 cycles of durvalumab)

Gemcitabine + cisplatin + S-1 as background gemcitabine-based chemotherapy every 2 weeks (i.e, 4 cycles of durvalumab)

Gemcitabine + S-1 as background gemcitabine-based chemotherapy every 3 weeks (i.e., 8 cycles of durvalumab)

Gemcitabine + cisplatin + albumin-bound paclitaxel as background gemcitabine-based chemotherapy every 3 weeks (i.e., 8 cycles of durvalumab)