412Background: Immune checkpoint inhibitors, such as nivo, an anti−PD-1 antibody, have demonstrated antitumor activity in various cancers. Chemotherapy has demonstrated immune system activation via multiple mechanisms, providing a rationale for combination approaches. nab-P + Gem is a standard of care in PC which does not require immunosuppressive corticosteroids. Here we report interim results from 2 PC cohorts (Arms A and B) of a phase I study in patients (pts) receiving nivo + nab-P ± Gem for locally advanced or metastatic PC. Methods: This 2-part study was designed to identify dose-limiting toxicities (DLTs) of nivo + nab-P ± Gem in Part 1 and assess tolerability and efficacy in Part 2 dose expansion (+ Gem). Pts were DLT evaluable if they received ≥ 2 cycles of treatment and remained on study for 14 days after last dose or discontinued due to a DLT prior to completing 2 cycles. After Arm A, Part 1 was deemed safe, Arm B, Part 1 was initiated. In Arm A, pts with 1 prior chemotherapy regimen received n...