I. To evaluate the toxicity of combination therapy with nab-paclitaxel (paclitaxel albumin-stabilized nanoparticle formulation), gemcitabine (gemcitabine hydrochloride) and AZD1775 (WEE1 inhibitor MK-1775) in patients with treatment-naive metastatic adenocarcinoma of the pancreas or locally-advanced adenocarcinoma of the pancreas which is not surgically resectable. (Phase I) II. To determine the dose of AZD1775 to be used in combination with nab-paclitaxel and gemcitabine chemotherapy in the phase II portion of the trial. (Phase I) III. To determine the pharmacokinetics of AZD1775 in combination with nab-paclitaxel and gemcitabine. (Phase I) IV. To evaluate progression-free survival (PFS) associated with nab-paclitaxel/gemcitabine/placebo or nab-paclitaxel/gemcitabine/AZD1775 in patients with metastatic adenocarcinoma of the pancreas. (Phase II)