This is a randomized, open-label, active-controlled, multicenter Phase III trial evaluating QLC5508 versus docetaxel in participants with metastatic castration-resistant prostate cancer (mCRPC) who have progressed after prior treatment with novel hormonal agents (NHAs). Participants are randomized to receive either QLC5508 monotherapy (experimental arm) or docetaxel (control arm). The primary objective is to compare the efficacy of QLC5508 versus docetaxel, as measured by radiographic progression-free survival (rPFS) assessed by an Independent Radiological Review Committee (IRC).