The purpose of this study is to compare overall survival of quemliclustat, nab-paclitaxel and gemcitabine versus placebo, nab-paclitaxel and gemcitabine in all randomized patients.

Inclusion Criteria:

• Have histologically or cytologically confirmed PDAC that is metastatic.

• Have not been previously treated for PDAC in the metastatic setting.

  1. Prior neoadjuvant and/or adjuvant therapy for PDAC is permitted if completed at least 12 months before randomization.
  2. Prior palliative radiotherapy is allowed if completed at least 2 weeks prior to randomization and AEs have resolved to Grade 1 or less before randomization.
  3. Prior and/or placement of a biliary stent/tube is permitted if any treatment-related AEs have improved to Grade ≤ 1 and the patient is not exhibiting any signs/symptoms of biliary obstruction.

• Eastern Cooperative Oncology Group PS of 0 to 1.

• At least 1 target lesion measurable by computed tomography (CT)/magnetic resonance imaging (MRI) per RECIST v1.1. not within a field of prior radiation therapy.

Exclusion Criteria:

• Previously treated for locally advanced, unresectable PDAC.
• History of brain metastases or leptomeningeal metastases.
• Prior treatment with a CD73 antagonist or inhibitor.
• Underlying medical conditions that, in the investigator or sponsor's opinion, will make the administration of study-specified therapy hazardous

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.

Arcus will provide access to individual de-identified participant data and related study documents (e.g., protocol, Statistical Analysis Plan [SAP], Clinical Study Report [CSR]) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions.