Interim [68Ga]Ga-prostate-specific membrane-antigen positron emission tomography/computed tomography has prognostic potential for overall survival in metastatic castrate-resistant prostate cancer, although evidence is limited. This ENZA-p sub-study evaluated 3-mo PSMA-total-tumor-volume as a prognostic biomarker for OS with enzalutamide ± [177Lu]Lu-PSMA-617.