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Poster display session

3569 - Phase II study of Prednisone-Dexamethasone switch in metastatic Castration Resistant Prostate Cancer (mCRPC) patients treated with Abiraterone and Prednisone (AA+P)


10 Sep 2017


Poster display session


Cytotoxic Therapy;  Prostate Cancer


Rebeca Lozano Mejorada


Annals of Oncology (2017) 28 (suppl_5): v269-v294. 10.1093/annonc/mdx370


R. Lozano Mejorada1, N. Romero Laorden2, A. Jayaram3, F. López4, M.I. Sáez5, R. Villatoro6, A. Montesa7, I. Moreno5, M. Ruiz Vico8, M. García Ferrón9, J. Rogado10, Y. Cendón Flórez11, P. Nombela Blanco2, L. Rivera2, G. Grau7, J.J. Cruz Hernandez1, D. Lorente Estelles12, G. Attard13, E. Castro Marcos2, D. Olmos Hidalgo14

Author affiliations

  • 1 Medical Oncology, Hospital Universitario de Salamanca, 37007 - Salamanca/ES
  • 2 Prostate Cancer Clinical Research Unit, Spanish National Cancer Research Centre, 28029 - Madrid/ES
  • 3 Gu Unit, The Institute of Cancer Research (ICR), SW7 3RP - London/GB
  • 4 Radiation Oncology, Hospital Universitario Ramon y Cajal, 28031 - Madrid/ES
  • 5 Medical Oncology, H Universitario Virgen de la Victoria y Regional de Málaga, Malaga/ES
  • 6 Medical Oncology, Hospital Costa del Sol, Málaga/ES
  • 7 Cnio-ibima Genitourinary Research Unit, Hospitales Universitarios Virgen de la Victoria y Regional de Málaga., Málaga/ES
  • 8 Medical Oncology, Hospital Universitario Carlos Haya, Málaga/ES
  • 9 Medical Oncology, Hospital Universitario Fundación Alcorcón, Madrid/ES
  • 10 Medical Oncology, Hospital Universitario de La Princesa, 28006 - Madrid/ES
  • 11 Prostate Cancer Unit, CNIO- Spanish National Cancer Center, 28029 - Madrid/ES
  • 12 Medical Oncology Department, Hospital Universitari i Politècnic La Fe, Valencia/ES
  • 13 Treatment Resistance, Division Of Molecular Pathology, The Institute of Cancer Research (Sutton Site), SM2 5NG - Sutton/GB
  • 14 Prostate Cancer Clinical Cancer Research Unit, Spanish National Cancer Research Centre (CNIO), Madrid/ES


Abstract 3569


Abiraterone Acetate (AA) improves overall survival in mCRPC patients. It is administered with prednisone (P) to decrease the adverse events derived from CYP171A supression. In phase I/II of AA without steroids, dexamethasone (D) 0.5mg/day was added after biochemical progression reaching a 25% of PSA decline. In a retrospective post-docetaxel cohort, Lorente et al (BJC,2014) reported that the switch induced durable biochemical responses in 40% of cases.


This is a multicentre-prospective phase II study. Its primary aim was to evaluate the antitumour activity of the change of concomitant P 5mg/12h to D 0.5mg/24h daily in mCRPC patients with biochemical and/or limited radiological progression after ≥12 weeks of AA+P treatment. Biochemical response and progression free survival (bPFS) were evaluated by PCWG2 criteria. Radiological response and PFS (rPFS) were evaluated after 12 weeks by RECIST and PCWG2 criteria. Using a single-stage ÁHern Phase II design a minimum of 6 PSA responses >30% in 25 enrolled patients were required to accept the alternative hypothesis (α:5%, 1-β:80%). PTEN and TMPRSS2-ERG in archival tumour-biopsies, AR aberrations in ctDNA and AR-V7 in exosomal RNA were evaluated. The Kaplan-Meier curves were used to calculate survival outcomes.


26 patients were included. Their clinical characteristics are shown in Table 1. No new safety concerns were observed with AA+D. A decline in PSA≥30% and ≥50% were observed in 12 (46%) and 8 (35%) patients, respectively; two radiological responses were observed; bPFS and rPFS after P to D switch were 4.2 months (CI 95% 2.2-6.2) and 11.8 months (CI 95% 6.9-16.8), respectively.Table:


CharacteristicsAA+D pre-CT (n = 14) N %AA+D post-CT N %
Age Median (range)72.9 60-8572.9 66-78
Baseline PSA Median (range)26.6 4.5-36739.9 6.9-1880
Gleason 6-7 8-10 UK5 36 8 57 1 76 50 6 50
ECOG 0-1 213 80 1 712 100
Metastases Bone Nodes Visceral12 86 8 57 1 712 100 4 33 3 25


In selected clinically stable mCRPC patients the P to D switch as adjuvant of AA could be an acceptable and active therapeutic option. Biomarkers correlation with P to D switch benefit will be reported.

Clinical trial identification


Legal entity responsible for the study

Spanish National Cancer Research Centre (CNIO)


Spanish National Cancer Research Centre (CNIO)


D. Lorente Estelles: Speaker fees and advisory boards: Janssen. All other authors have declared no conflicts of interest.

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