A Study to Evaluate the Safety and Tolerability of AB680 in Participants With Gastrointestinal Malignancies

Dose escalation of AB680 in combination with zimberelimab (AB122), nab-paclitaxel and gemcitabine will be assessed in participants with advanced pancreatic cancer. In this dose escalation combination study, participants with advanced pancreatic cancer will receive escalating doses of AB680 in combination with zimberelimab at the recommended phase 2 dose (RP2D), and nab-paclitaxel and gemcitabine at standard doses. AB680, zimberelimab, nab-paclitaxel and gemcitabine are all administered via IV infusion. In the dose expansion portion of the study in front-line (1L) pancreatic patients, participants will receive AB680 at the RP2D determined from the dose escalation study in combination with zimberelimab at the RP2D and nab-paclitaxel and gemcitabine at standard doses or AB680 at the RP2D in combination with nab-paclitaxel and gemcitabine at standard doses. In the dose-expansion portion of the study in second-line (2L) pancreatic patients, participants will receive AB680 at the RP2D determined from the dose-escalation study in combination with zimberelimab at the RP2D and nab-paclitaxel and gemcitabine at standard doses.