Prior reports have reported a good correlation between changes in the total PSMA-positive tumor volume (TTV) under therapy and clinical outcome; however, they differ in their used imaging modality (PET/CT or SPECT/CT) as well as compared time points (6 weeks or 12 weeks after start of therapy) and used compound ([177Lu]Lu-PSMA-617 or [177Lu]Lu-PSMA I&T) [4–6]. The gene discussed is FOLH1; the disease is neoplasm.