Observational study on time on treatment with abiraterone and enzalutamide

• Introduction The aim of this study was to assess time on treatment with abiraterone and enzalutamide, two androgen receptor targeted (ART) drugs, the impact on time on treatment of time interval without drug supply between prescription fillings, and adherence to treatment. Material and methods By use of data from The National Prostate Cancer Register, The Prescribed Drug Registry and the Patient Registry, time on treatment with the abiraterone and enzalutamide was analyzed in all men with castration resistant prostate cancer (CRPC) in Sweden 2015-2019. Three time intervals between consecutive fillings, i.e. time without drug supply, were assessed. Adherence to the treatment was evaluated by use of the Medication Possession Ratio. Kaplan Meier analysis and multivariable Cox regression model were used to assess factors affecting time on treatment. Results Between January 2015 and October 2019, 1803 men filled a prescription for abiraterone and 4 534 men filled a prescription for enzalutamide. With a time interval of 30 days or less between two fillings, median time on treatment was 4.9 months (IQR 2.6-11.7) for abiraterone and 8.0 months (IQR 3.6-16.4) for enzalutamide. In sensitivity analyses, allowing for no more than 14 days without drug supply between fillings, median time on treatment was 3.9 months (IQR 2.1-9.0) for abiraterone and 5.9 months (IQR 2.8-12.1) for enzalutamide. Allowing for any time period without drug between fillings, median time on treatment was 5.7 months (IQR 2.7-14.0) for abiraterone and 9.8 months (IQR 4.4-21.0) for enzalutamide. Adherence to treatment was above 90% for both drugs. Conclusion Time on treatment with abiraterone and enzalutamide was shorter in clinical practice than in randomized controlled trials and varied almost two-fold with time interval without drug. Adherence to treatment was high. The main limitation of our study was the lack of data on use of chemotherapy.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

Keyword

resistant prostate-cancer

medication adherence

survival analysis

double-blind

acetate

men

chemotherapy

register

prednisone

experience

Science & Technology - Other Topics

RESISTANT PROSTATE-CANCER

Publication and Content Type

ref (subject category)

art (subject category)