 To estimate the treatment effect on overall survival, feasibility, efficacy and safety of alternating treatment cycles of gemcitabine monotherapy followed by nab-paclitaxelgemcitabine relative to standard continuing nab-paclitaxelgemcitabine cycles in first-line treatment for metastatic pancreatic cancer in patients having received 3 cycles of induction therapy with standard nab-paclitaxelgemcitabine. 