ASCO GU 2018: Treatment Duration And Utilization Patterns In Metastatic Castration-resistant Prostate Cancer Patients Receiving Enzalutamide or Abiraterone Acetate

San Francisco, CA (UroToday.com) Enzalutamide (ENZA) and abiraterone acetate (ABI) are approved hormonal therapies for men with metastatic castration-resistant prostate cancer (mCRPC). The authors presented a study assessing the real-world treatment duration and utilization patterns in patients receiving ENZA or ABI.

Methods:
Adult mCRPC patients initiating ENZA or ABI before or after cytotoxic chemotherapy were identified from the Truven MarketScan® claims database (2012–2015). The index date was the first initiation of ENZA or ABI. Treatment discontinuation was defined as a prescription gap of ≥45 days. Treatment switching was defined as starting a new mCRPC-related therapy within 30 days before to 45 days after the discontinuation date. Analyses were separately conducted for chemo-naïve and chemo-experienced patients.

Results:
The study included 3230 chemo-naive (ENZA 920; ABI 2310) and 692 chemo-experienced patients (ENZA 262; ABI 430).
Among chemo-naive patients:
ENZA cohort had older patients (mean age 74.5 vs 73.5; p = 0.013), with a higher proportion of comorbidities, when compared to the ABI cohort. Treatment duration was longer for the ENZA cohort than for the ABI cohort (log-rank p = 0.008; median = ENZA 10.7 vs ABI 8.8 months). Within 1 year of initiation, 55.7% of ENZA and 60.8% of ABI cohort discontinued treatment and 22.5% and 34.7%, respectively, switched to other mCRPC therapies. Results were consistent among subgroups with specific comorbidities.
Among chemo experienced patients:
The treatment duration was shorter than for chemo-naive patients; the difference between ENZA vs ABI was not statistically significant (log-rank p = 0.255; median = ENZA 7.5 vs ABI 7.1 months).

Conclusions:
Despite a more complex profile at baseline, chemo-naive mCRPC patients in the ENZA cohort had a longer treatment duration and lower proportion of switching to other prostate-cancer-directed therapies, when compared to the ABI cohort. In contrast, the difference of treatment duration between the two cohorts was not statistically significant for chemo-experienced patients.

Presented by: Vahan Kassabian

Written by: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre, Twitter:@GoldbergHanan at the 2018 American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium, February 8-10, 2018 - San Francisco, CA
E-Newsletters

Newsletter subscription

Free Daily and Weekly newsletters offered by content of interest

The fields of GU Oncology and Urology are rapidly advancing. Sign up today for articles, videos, conference highlights and abstracts from peer-review publications by disease and condition delivered to your inbox and read on the go.

Subscribe