Phase I/II Study to Evaluate Nab-paclitaxel in Substitution of CPT11 or Oxaliplatin in FOLFIRINOX Schedule as First Line Treatment in Metastatic Pancreatic Cancer

The primary objective for phase I of the study is to determine the MTD of Nab-p when used in substitution of OXA or CPT11 in FOLFIRINOX schedule, as first-line treatment in pts with mPC. The dose finding strategy will be based on the classical 3+3 dose escalation design. -Analysis sets: Modified intention-to-treat population: it consists of all pts who are allocated and receive at least one dose of any component of study treatment. Pts will be grouped according to the randomized treatment assignment. Pts treated during the phase I step will be not included in this population. Safety population: it consists of all pts who are allocated and receive at least one dose of any component of study treatment. Groups are defined by the study treatment actually received. Pts treated at the MTD during the phase I step will be not included in this population. Statistical methods Best ORR will be summarized and 95% confidence limits will be calculated according to the exact method for each of the treatment arms included in the phase II step. All the analyses of primary and secondary efficacy variables will be performed on the modified intention-to-treat population. The overall incidences of AEs will be summarized. Pts who experienced the same event on more than one occasion are counted only once in the calculation of the event frequency, at the highest intensity ever observed. Serious adverse events will be summarized. All the safety analyses will be performed on the safety population. -Sample size: The experimental treatment, to be considered clinically worthwhile, should determine an overall best RR equal to or greater than 40%. According to the Fleming single stage design, for a 90% power towards an alternative hypothesis of an ORR equal to or greater than 40% and a one-sided type I error rate of 5%, respect to the null hypothesis of an ORR equal to or less than 20%, 42 pts must be included in the final evaluation, in each arm of the phase II step. According to the exact binomial test, the experimental treatment will be considered sufficiently promising and candidate to further studies in the case of a major objective response is seen in at least 14 pts.