Study of PEGPH20 With Cisplatin (CIS) and Gemcitabine (GEM); PEGPH20 With Atezolizumab (ATEZO), CIS, and GEM; and CIS and GEM Alone in Participants With Previously Untreated, Unresectable, Locally Advanced, or Metastatic Intrahepatic and Extrahepatic Cholangiocarcinoma and Gallbladder Adenocarcinoma

The study will have a Run-in portion and an Expansion portion. The Run-in portion will be used to evaluate the safety profile of the PEGCISGEM and PEGCISGEMATEZO treatments prior to evaluating the efficacy and safety of PEGCISGEM and PEGCISGEMATEZO treatments compared with CISGEM treatment in the Expansion portion of the study. Treatment in both portions of the study will continue until death, withdrawal of consent from the study, disease progression, or unacceptable toxicity.