Reply to Ugo De Giorgi, Vincenza Conteduca, and Emanuela Scarpi's Letter to the Editor re: Marzia Del Re, Elisa Biasco, Stefania Crucitta, et al. The Detection of Androgen Receptor Splice Variant 7 in Plasma-derived Exosomal RNA Strongly Predicts Resistance to Hormonal Therapy in Metastatic Prostate Cancer Patients. Eur Urol 2017;71:680–7