Prostate cancer tissues often contain immune cells, suggesting that this cancer is a target of host antitumor immunity.39 In 2010, sipuleucel-T, a cancer vaccine that targets prostatic acid phosphatase, was approved by Food and Drug Administration for the first immunotherapy of mCRPC.40 However, other immunotherapeutic approaches, including immune checkpoint inhibitors such as ipilimumab and pembrolizumab, have not been successful against mCRPC to date.13–15 This failure may be explained by highly immunosuppressive microenvironment in prostate cancer. Here, ACP3 is linked to cancer.