Advanced pancreatic ductal adenocarcinoma is a fatal disease with about 6 months of median overall survival (OS). Gemcitabine is the only approved single agent. Gemcitabine-based chemotherapy did not show benefit in OS during the past decade. The recent phase III trial MPACT (Metastatic Pancreatic Adenocarcinoma Clinical Trial) demonstrated an improvement in overall response rate (ORR), progression free survival (PFS) and OS, with nab-paclitaxel (125 mg/m2 on day 1, 8 and 15 every 28 days) plus gemcitabine (1000 mg/m2 on day 1, 8 and 15 every 28 days) compared to gemcitabine alone. Accordingly the combination of nab-paclitaxel with gemcitabine became one of standard treatments in metastatic pancreatic cancer. A Chinese phase II trial showed the modified dosage of nab-paclitaxel (120 mg/m2 on day 1 and 8 every 21 days) plus gemcitabine (1000 mg/m2 on day 1 and 8 every 21 days) is more suitable for Chinese patients. This study aims to explore the efficacy and safety of the tentative dosage of nab-paclitaxel (125 mg/m2 on day 1 and 8, every 21 days) and gemcitabine (1000 mg/m2 on day 1 and 8, every 21 days) for Chinese patients.