title: Very Early PSA Response to Abiraterone in mCRPC Patients: A Novel Prognostic Factor Predicting Overall Survival.
abstract: BACKGROUND
  Abiraterone Acetate (AA) is approved for the treatment of mCRPC after failure of androgen deprivation therapy in whom chemotherapy is not yet clinically indicated and for treatment of mCRPC progressed during or after docetaxel-based chemotherapy regimen. The aim of this study is to evaluate the role of early PSA decline for detection of therapy success or failure in mCRPC patients treated with AA in post chemotherapy setting.
  
  
  METHODS
  We retrospectively evaluated 87 patients with mCRPC treated with AA. Serum PSA levels were evaluated after 15, 90 days and then monthly. The PSA flare phenomenon was evaluated, according to a confirmation value at least 1 week apart. The primary endpoint was to demonstrate that an early PSA decline correlates with a longer progression free survival (PFS) and overall survival (OS). The secondary endpoind was to demonstrate a correlation between better outcome and demographic and clinical patient characteristics.
  
  
  RESULTS
  We have collected data of 87 patients between Sep 2011 and Sep 2014. Early PSA response (≥50% from baseline at 15 days) was found in 56% evaluated patients and confirmed in 29 patients after 90 days. The median PFS was 5.5 months (4.6-6.5) and the median OS was 17.1 months (8.8-25.2). In early responders patients (PSA RR ≥ 50% at 15 days), we found a significant statistical advantage in terms of PFS at 1 year, HR 0.28, 95%CI 0.12-0.65, p = 0.003, and OS, HR 0.21 95% CI 0.06-0.72, p = 0.01. The results in PFS at 1 years and OS reached statistical significance also in the evaluation at 90 days.
  
  
  CONCLUSIONS
  A significant proportion (78.6%) of patients achieved a rapid response in terms of PSA decline. Early PSA RR (≥50% at 15 days after start of AA) can provide clinically meaningful information and can be considered a surrogate of longer PFS and OS.
authors.affiliation: Division of Medical Oncology, Department of Uro-Gynaecological Oncology, Istituto Nazionale Tumori "Fondazione G. Pascale" - IRCCS Naples, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Facchini
authors.affiliation: Department of Medical Oncology, Santa Chiara Hospital Trento, Italy.
authors.forename: Orazio
authors.initials: O
authors.lastname: Caffo
authors.affiliation: Medical Oncology Department, Institute for Cancer Research and Treatment Candiolo, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Ortega
authors.affiliation: Department of Onco-Ematology Medical Oncology, S.G. Moscati Hospital of Taranto Taranto, Italy.
authors.forename: Carmine
authors.initials: C
authors.lastname: D'Aniello
authors.affiliation: Division of Medical Oncology, Department of Uro-Gynaecological Oncology, Istituto Nazionale Tumori "Fondazione G. Pascale" - IRCCS Naples, Italy.
authors.forename: Marilena
authors.initials: M
authors.lastname: Di Napoli
authors.affiliation: Division of Medical Oncology, Department of Uro-Gynaecological Oncology, Istituto Nazionale Tumori "Fondazione G. Pascale" - IRCCS Naples, Italy.
authors.forename: Sabrina C
authors.initials: SC
authors.lastname: Cecere
authors.affiliation: Division of Medical Oncology, Department of Uro-Gynaecological Oncology, Istituto Nazionale Tumori "Fondazione G. Pascale" - IRCCS Naples, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Della Pepa
authors.affiliation: Unit of Epidemiology, Struttura Complessa di Statistica Medica, Biometria e Bioinformatica, Fondazione IRCCS Istituto Nazionale Tumori Naples, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Crispo
authors.affiliation: Department of Medical Oncology, Santa Chiara Hospital Trento, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Maines
authors.affiliation: Medical Oncology Department, Institute for Cancer Research and Treatment Candiolo, Italy.
authors.forename: Fiorella
authors.initials: F
authors.lastname: Ruatta
authors.affiliation: Division of Medical Oncology, Department of Uro-Gynaecological Oncology, Istituto Nazionale Tumori "Fondazione G. Pascale" - IRCCS Naples, Italy.
authors.forename: Gelsomina
authors.initials: G
authors.lastname: Iovane
authors.affiliation: Department of Onco-Ematology Medical Oncology, S.G. Moscati Hospital of Taranto Taranto, Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Pisconti
authors.affiliation: Unit of Epidemiology, Struttura Complessa di Statistica Medica, Biometria e Bioinformatica, Fondazione IRCCS Istituto Nazionale Tumori Naples, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Montella
authors.affiliation: Department of Medical Oncology, National Cancer Institute Aviano, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Berretta
authors.affiliation: Division of Medical Oncology, Department of Uro-Gynaecological Oncology, Istituto Nazionale Tumori "Fondazione G. Pascale" - IRCCS Naples, Italy.
authors.forename: Sandro
authors.initials: S
authors.lastname: Pignata
authors.affiliation: Department of Onco-Ematology Medical Oncology, S.G. Moscati Hospital of Taranto Taranto, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Cavaliere
keywords: PSA detection; abiraterone acetato; metastatic castration resistant prostate cancer; overall survival; prognostic factors; prostate cancer