Inhibition of the Cellular FLICE-like Inhibitory Protein (cFLIP), which is overexpressed in prostate cancer, alongside TRAIL treatment can trigger apoptosis and suppress cancer stem cell (CSC) activity in different cancer types but has not been fully explored in prostate cancer.<h4>Methods</h4>Established and primary prostate cancer lines were treated with the cFLIP inhibitor, OH14, in combination with recombinant TRAIL to investigate changes in viability and colony forming potential. This evidence concerns the gene CFLAR and Familial prostate cancer.