XIAP and prostate cancer: On the contrary, in patients that remained with active disease after treatment with melanoma vaccine, low to intermediate levels rather than absence of protein is associated with favorable prognosis due to paradoxical pro-apoptotic ML-IAP activity.20, 58 Furthermore, higher levels of IAPs (BIRC1-5) were reported in prostate cancer cell lines as well as prostate cancer samples without any clinical correlation.59, 60 However, some recent studies have identified XIAP expression as an independent favorable prognostic marker for longer relapse-free survival in prostate cancer patients (Table 2).