Value of treatment in clinical trials versus the real world: the case of abiraterone acetate (Zytiga) for postchemotherapy metastatic castration-resistant prostate cancer patients in Sweden

Abstract

Objective: In a randomized clinical trial (COU-AA-301), abiraterone acetate (Zytiga^®) was shown to be superior to prednisone in the treatment of metastatic castration-resistant prostate cancer (mCRPC). However, the value of abiraterone treatment for patients with mCRPC in clinical practice in Sweden is not known. The aim of this study was to compare the outcomes and treatment patterns of abiraterone treatment in a Swedish observational study to those of the pivotal clinical trial, thereby discussing the external validity of the postchemotherapy clinical trial from a Swedish perspective.

Materials and methods: A retrospective chart review was conducted using data from three Swedish hospitals. Data were retrieved from 119 eligible patients diagnosed with mCRPC, treated during 2013 and 2014. Swedish real-world evidence sample characteristics, treatment patterns and duration, and overall survival were compared to the clinical trial data.

Results: Analyses of the data showed that patients were treated for a median of 5.6 months, which was significantly shorter than the treatment duration in the clinical trial (7.3 months). A comparison indicated that the Swedish patients were similar to patients included in the clinical trial in observed patient characteristics, but perhaps less likely to benefit from treatment owing to prior ketoconazole treatment and possibly higher Eastern Cooperative Oncology Group performance status. Despite this, the Swedish patients had non-significantly longer overall survival and significantly shorter treatment duration.

Conclusion: Swedish patients could expect the same overall survival as patients randomized to abiraterone in the clinical trial despite shorter treatment duration, leading to a more cost-effective use of the treatment in the real world compared to the clinical trial.

Keywords:

• Abiraterone acetate
• clinical practice
• external validity
• metastatic castration-resistant prostate cancer

Acknowledgements

We thank Anna Laurell at Akademiska sjukhuset, Uppsala, and Carola Svensson at Blekingesjukhuset, Karlskrona, for participating in the data collection process.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Funding information

This work was supported by Janssen-Cilag AB.