Pancreatic cancer is a common malignancy of digestive system with gradually increasing incidence, is the fourth and seventh leading cause of cancer-related mortality in the world (1) and China (2) according to the statistics in 2014. The vast majority of patients were confirmed as locally advanced or distantly metastatic disease at diagnosis with an estimated five-year survival rate of 4% (3) due to occlusive development and rapid progress. Advanced pancreatic cancer is characterized by poor prognosis.

Gemcitabine has been approved as the standard chemotherapy for advanced pancreatic cancer since 1996, but the efficacy is extremely limited by a response rate of 6-8%, and median survival of 5.5-7 months. However, Gemcitabine-based combination treatments fail to transcend GEM monotherapy on overall survival, including GEM + 5-Fu [10], GEM + Oxaliplatin[11], and GEM + Irinotecan [12] and GEM + Cisplatin [13] (7-8) . Until 2011, Conroy et al.[15] reported that FOLFIRINOX solutions significantly improved ORR (31.6% vs 9%, P=0.0008), PFS (6.4 vs. 3.3 months, P<0.0001) and OS (11.1 vs. 6.8 months, P<0.001) than GEM single-agent, but the significant increase of grade 3/4 adverse reactions, to some extent, limited its wide application. Therefore, it is necessary to continue to explore effective and safe chemotherapy of advanced pancreatic cancer.

Nab-Paclitaxel was approved by FDA for advanced pancreatic cancer in September 2013. S-1 has demonstrated potential value in the treatment of advanced pancreatic cancer as a new compound oral 5-FU(4-5) and has been approved for pancreatic cancer treatment in Japan.

We conducted a single arm, prospective, phase II study in our center on the first-line treatment of advanced pancreatic cancer with nab-Paclitaxel and S-1 to investigate the efficacy and safety of the combination regimen.

Inclusion Criteria:

• Age, years: 18-75
• Histologically and cytologically confirmed advanced pancreatic cancer , inresectable, measurable lesions according to RECIST criteria; ECOG score of 0-1; life expectancy ≥12 weeks;
• Untreated; more than 6 months after the last adjuvant chemotherapy (does not include taxanes and S1);
• Laboratory examination within 14 days before entering the study should meet following requirements: ANC ≥ 1.5 x 10^9/L; PLT ≥ 100 x 10^9/L; Hb ≥ 90g/L (9g/dL); AST, ALT ≤ 2.5 x ULN (with no liver metastasis), ≤ 5 x ULN（with liver metastasis); creatinine ≤ 1.5 x ULN; TBIL ≤ 1.5 x ULN
• Both male and female subjects of potential fertility have to agree effective birth control during the entire study
• Informed consent

Exclusion Criteria:

• Concurrent other effective treatment (including radiotherapy)
• Resectable patients
• Allergy history to other drugs in the same class patients with pregnancy or lactation
• Known severe internal medical diseases
• Abnormal heart function or relevant history of myocardial infarction and severe arrhythmia
• Immunocompromised patients, such as HIV positive
• Uncontrollable mental illness
• Other conditions the researchers considered ineligible for the study