title: Tumour responses following a steroid switch from prednisone to dexamethasone in castration-resistant prostate cancer patients progressing on abiraterone.
abstract: BACKGROUND
  Abiraterone is a CYP17A1 inhibitor that improves survival in castration-resistant prostate cancer (CRPC). Abiraterone is licensed in combination with prednisone 5 mg twice daily to prevent a syndrome of secondary mineralocorticoid excess. We hypothesised that a 'steroid switch' from prednisone to dexamethasone would induce secondary responses in patients progressing on abiraterone and prednisone 5 mg b.i.d.
  
  
  METHODS
  We performed a 'steroid switch' in patients with CRPC at PSA progression on abiraterone and prednisolone. Patients were monitored for secondary declines in PSA, radiological tumour regression and toxicity.
  
  
  RESULTS
  A retrospective analysis of 30 CRPC patients who underwent a steroid switch from prednisolone to dexamethasone while on abiraterone was performed. A total of six patients (20%) had a ⩾50% PSA decline that was confirmed by a second PSA level at least 3 weeks later. In all, 11 patients (39.2%) had a confirmed ⩾30% PSA decline. Median time to PSA progression on abiraterone and dexamethasone was 11.7 weeks (95% CI: 8.6-14.8 weeks) in the whole cohort and 27.6 weeks (95% CI: 14.5-40.7 weeks) in patients who achieved a confirmed 50% PSA decline. Nine patients had RECIST evaluable disease: two of these patients had RECIST partial response, six patients had stable disease and one patient had progressive disease at the first imaging assessment. Treatment was well tolerated, with no grade 3 and grade 4 adverse events. One patient had to be reverted to prednisolone because of grade 2 hypotension.
  
  
  CONCLUSIONS
  Durable PSA responses occur in up to 40% of patients following a 'steroid switch' for PSA progression on abiraterone and prednisone. Studies are ongoing to elucidate the mechanisms underlying this response.
authors.affiliation: Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: D
authors.initials: D
authors.lastname: Lorente
authors.affiliation: 1] Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton SM2 5PT, Surrey, UK [2] Kantonsspital St. Gallen, Department of Oncology and Haematology, Rorschacherstrasse 95, CH-9007 St. Gallen, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Omlin
authors.affiliation: Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: R
authors.initials: R
authors.lastname: Ferraldeschi
authors.affiliation: Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: C
authors.initials: C
authors.lastname: Pezaro
authors.affiliation: Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: R
authors.initials: R
authors.lastname: Perez
authors.affiliation: Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: J
authors.initials: J
authors.lastname: Mateo
authors.affiliation: Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: A
authors.initials: A
authors.lastname: Altavilla
authors.affiliation: Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: Z
authors.initials: Z
authors.lastname: Zafeirou
authors.affiliation: Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: N
authors.initials: N
authors.lastname: Tunariu
authors.affiliation: Academic Urology Unit, The Royal Marsden NHS Foundation Trust, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: C
authors.initials: C
authors.lastname: Parker
authors.affiliation: Academic Urology Unit, The Royal Marsden NHS Foundation Trust, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: D
authors.initials: D
authors.lastname: Dearnaley
authors.affiliation: Kantonsspital St. Gallen, Department of Oncology and Haematology, Rorschacherstrasse 95, CH-9007 St. Gallen, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Gillessen
authors.affiliation: Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: J
authors.initials: J
authors.lastname: de Bono
authors.affiliation: Prostate Cancer Targeted Therapy Group and Drug Development Unit, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton SM2 5PT, Surrey, UK.
authors.forename: G
authors.initials: G
authors.lastname: Attard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000736:Androstenes / Q000627:therapeutic use*; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D003907:Dexamethasone / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011241:Prednisone / Q000627:therapeutic use*; D064129:Prostatic Neoplasms, Castration-Resistant / Q000188:drug therapy* / Q000473:pathology; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D000736:Androstenes; D000893:Anti-Inflammatory Agents; D003907:Dexamethasone; C089740:abiraterone; D011241:Prednisone