Masitinib is a selective tyrosine kinase inhibitor that is thought to promote survival via modulation of immunostimulation-mediated anticancer effects and modulation of the tumor microenvironment. The objective of this study is to evaluate the efficacy and safety of masitinib in combination with gemcitabine as compared with single agent gemcitabine in advanced or metastatic epithelial ovarian cancer patients who are refractory to platinum treatment. This is an open-label, randomized, active-controlled, phase 2/3 study. The study's primary efficacy measure will be overall survival. Masitinib will be prescribed until disease progression (or treatment switch to next line of treatment), death, limiting toxicity or patient consent withdrawal. The study design is a two-stage adaptive design, meaning that it includes a prospectively planned opportunity for modification of one or more specified aspects of the study (for example patient enrollment).