Kyriakopoulos CE, Heath EI, Ferrari A, et al. - The present study was performed to evaluate spatial-temporal variations in ¹⁸F-sodium fluoride PET/CT and circulating tumor cells in metastatic castration-resistant prostate cancer treated with enzalutamide. Researchers included men with progressive metastatic castration-resistant prostate cancer with at least two lesions on bone scintigraphy and treated with enzalutamide 160 mg daily. They obtained ¹⁸F-NaF PET/CT scans at baseline (PET1), week 13 (PET2), and at the time of prostate-specific antigen progression, standard radiographic or clinical progression, or at 2 years without progression (PET3). They applied quantitative total bone imaging (QTBI) to ascertain lesion-level response. The proportion of men with at least one responding bone lesion on PET3 using QTBI was the primary endpoint. The study included a total of 23 men. The data revealed that the proportion of progressing lesions was low, demonstrating that a substantial number of lesions seem to continue to benefit from enzalutamide beyond progression. The results recognized that selective targeting of nonresponding lesions may be a reasonable method to extend benefit.