title: Independent association between time to prostate-specific antigen (PSA) nadir and PSA progression-free survival in patients with docetaxel-naïve, metastatic castration-resistant prostate cancer receiving abiraterone acetate, but not enzalutamide.
abstract: The objective of this study was to compare the prognostic effect of time to prostate-specific antigen (PSA) nadir (TTPN) after treatment with abiraterone acetate (AA) and enzalutamide (Enz) in patients with docetaxel-naïve, metastatic castration-resistant prostate cancer (mCRPC).
  
  
  
  This study included a total of 297 consecutive patients with mCRPC, of whom 125 and 172 received AA and Enz, respectively, without previous treatment with docetaxel and subsequently achieved any degree of PSA reduction after the administration of either agent.
  
  
  
  The mean values of TTPN in the AA and Enz groups were 19 and 14 weeks, respectively. Despite the lack of significant differences in several parameters according to the mean TTPN in the Enz group, patients with TTPN>19 weeks were characterized by longer duration of androgen deprivation therapy, better performance status, lower incidence of bone metastasis, lower value of nadir PSA, and higher incidence of PSA response than those with TTPN ≤19 weeks in the AA group. The PSA progression-free survival (PFS) in patients with TTPN >19 weeks was significantly superior when compared with TTPN ≤19 weeks in the AA group; however, there was no significant effect of the mean TTPN on the PSA-PFS in the Enz group. Furthermore, TTPN was identified as one of the independent predictors of PSA-PFS in the AA group but not in Enz group.
  
  
  
  A longer time to reach a PSA nadir after treatment with AA, but not Enz, appeared to be associated with favorable disease control in patients with docetaxel-naïve mCRPC.
authors.affiliation: Department of Urology, Hamamatsu University School of Medicine, Hamamatsu, Japan; Division of Urology, Kobe University Graduate School of Medicine, Kobe, Japan. Electronic address: hideakimiyake@hotmail.com.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Miyake
authors.affiliation: Division of Urology, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Takuto
authors.initials: T
authors.lastname: Hara
authors.affiliation: Department of Urology, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Tamura
authors.affiliation: Department of Urology, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Sugiyama
authors.affiliation: Department of Urology, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Furuse
authors.affiliation: Department of Urology, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Ozono
authors.affiliation: Division of Urology, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Fujisawa
mesh_terms: D000069501:Abiraterone Acetate / Q000627:therapeutic use*; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001549:Benzamides; D018572:Disease-Free Survival; D000077143:Docetaxel; D006801:Humans; D007610:Kallikreins / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009570:Nitriles; D010669:Phenylthiohydantoin / Q000031:analogs & derivatives* / Q000627:therapeutic use; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood*; D064129:Prostatic Neoplasms, Castration-Resistant / Q000097:blood* / Q000188:drug therapy*; D012189:Retrospective Studies; D043823:Taxoids / Q000008:administration & dosage; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D009570:Nitriles; D043823:Taxoids; D000077143:Docetaxel; D010669:Phenylthiohydantoin; C540278:enzalutamide; C549870:KLK3 protein, human; D007610:Kallikreins; D017430:Prostate-Specific Antigen; D000069501:Abiraterone Acetate
keywords: Abiraterone acetate; Castration-resistant prostate cancer; Enzalutamide; Time to PSA nadir