title: Number needed to treat and associated incremental costs of treatment with enzalutamide versus abiraterone acetate plus prednisone in chemotherapy-naïve patients with metastatic castration-resistant prostate cancer.
abstract: OBJECTIVE
  Enzalutamide (ENZA) and abiraterone acetate plus prednisone (AA) are approved second-generation hormone therapies for chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC). This study compared ENZA with AA in chemotherapy-naïve mCRPC by calculating the number needed to treat (NNT) and associated incremental costs to achieve one additional chemotherapy-naïve patient with mCRPC free of radiographic progression, chemotherapy, or death over a 1-year time horizon.
  
  
  METHODS
  Clinical outcomes were obtained from the PREVAIL and COU-AA-302 trials. Three outcomes were evaluated: radiographic progression-free survival, time to cytotoxic chemotherapy initiation, and overall survival at 1 year. NNT was calculated as the reciprocal of the outcome event rate difference for ENZA compared with AA. The incremental costs to achieve one additional outcome at 1 year were calculated as the difference in cost per treated patient multiplied by the NNT. Per-treated-patient costs were considered from a US payer perspective and included medications, monitoring, adverse events, post-progression treatments, and end-of-life care.
  
  
  RESULTS
  Within a 1-year time horizon, the total cost per treated patient for ENZA was $2,666 less than AA. Compared with AA, treating 14 patients with ENZA resulted in one additional patient free of progression or death over 1 year; treating 26 patients with ENZA resulted in one additional patient with chemotherapy delayed over 1 year; and treating 91 patients with ENZA resulted in one additional patient free of death over 1 year. Therefore, ENZA is cost-effective compared with AA for all three outcomes evaluated, and the modeled results suggest ENZA is associated with potentially improved clinical outcomes in delaying chemotherapy initiation and disease progression for chemotherapy-naïve patients. The results are robust in sensitivity analyses, where the effect of changes in key model inputs and assumptions were tested.
  
  
  CONCLUSIONS
  The results modeled in the present study suggest ENZA is cost-effective compared with AA for treating chemotherapy-naïve patients with mCRPC.
authors: a Astellas Pharma, Inc. , Northbrook , IL , USA.
authors: Marjan
authors: M
authors: Massoudi
authors: b Medivation, Inc. , San Francisco , CA , USA.
authors: Mark
authors: M
authors: Balk
authors: c Analysis Group , Boston , MA , USA.
authors: Hongbo
authors: H
authors: Yang
authors: a Astellas Pharma, Inc. , Northbrook , IL , USA.
authors: Cat N
authors: CN
authors: Bui
authors: a Astellas Pharma, Inc. , Northbrook , IL , USA.
authors: Bhavik J
authors: BJ
authors: Pandya
authors: c Analysis Group , Boston , MA , USA.
authors: Jenny
authors: J
authors: Guo
authors: c Analysis Group , Boston , MA , USA.
authors: Yan
authors: Y
authors: Song
authors: c Analysis Group , Boston , MA , USA.
authors: Eric Q
authors: EQ
authors: Wu
authors: a Astellas Pharma, Inc. , Northbrook , IL , USA.
authors: Bruce
authors: B
authors: Brown
authors: b Medivation, Inc. , San Francisco , CA , USA.
authors: Arie
authors: A
authors: Barlev
authors: a Astellas Pharma, Inc. , Northbrook , IL , USA.
authors: Scott
authors: S
authors: Flanders
mesh_terms: D000069501:Abiraterone Acetate / Q000008:administration & dosage* / Q000191:economics*; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000191:economics*; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage* / Q000191:economics*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage* / Q000191:economics*; D003362:Cost-Benefit Analysis; D018572:Disease-Free Survival; D006801:Humans; D008297:Male; D011241:Prednisone / Q000008:administration & dosage* / Q000191:economics*; D064129:Prostatic Neoplasms, Castration-Resistant / Q000188:drug therapy*
chemical_list: D000970:Antineoplastic Agents; D018931:Antineoplastic Agents, Hormonal; D000069501:Abiraterone Acetate; D011241:Prednisone
keywords: Abiraterone; Castration-resistant prostate cancer; Cost per outcome; Cost-effectiveness; Enzalutamide; Number needed to treat