EAU 2021: Time on Treatment with Abiraterone and Enzalutamide in the Patient-Overview Prostate Cancer in the National Prostate Cancer Register of Sweden

(UroToday.com) At the metastatic prostate cancer session at the European Association of Urology 2021 annual meeting, Dr. Giuseppe Fallara discussed the impact of time on treatment with abiraterone or enzalutamide among men with metastatic castration resistant prostate cancer (mCRPC). To date, there are little real-world data on the time of treatment with abiraterone and enzalutamide in men with mCRPC. The objective of this study was to assess time on treatment with abiraterone and enzalutamide from population-based data and to compare it with that reported in randomized control trials. 


In this cohort study of men with mCRPC treated with androgen receptor targeted agents in 2015-2019 from the Patient-overview Prostate Cancer (PPC), a part of The National Prostate Cancer Register (NPCR) of Sweden, time on treatment was assessed by use of data in PPC and assessed by Kaplan-Meier plots and Cox regression. To assess representativity of PPC, a comparison was made with all men in NPCR, which captures all prostate cancer cases in Sweden, who filled a prescription for androgen receptor targeted agents in the Prescribed Drug Registry.

There were 2,038 men registered in PPC that had received an androgen receptor targeted agent: 493 received abiraterone in chemo-naïve and 110 in post-docetaxel setting, whereas 1,108 received enzalutamide in chemo-naïve and 327 in post-docetaxel setting. Median time on treatment in chemo-naïve men was 10.8 (95% CI 9.1-13.1) months for abiraterone and 14.1 (95% CI 13.5-15.5) for enzalutamide, versus 13.8 months reported in COU-AA-3021 and 16.6 months in PREVAIL.2 After use of docetaxel, it was 8.2 (95% CI 6.5-12.4) months for abiraterone and 11.1 (95% CI 9.8-12.6) for enzalutamide, versus 8 months reported in COU-AA-3013 and 8.3 months in AFFIRM:4

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Men in PPC were older and had more comorbidities and a poorer performance status than in randomized controlled trials:

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PPC captured 2522/6337 (40%) of all men in NPCR who filled a prescription for androgen receptor targeted agents. Based on fillings in the Prescribed Drug Registry, men in PPC had a median time on treatment with the two androgen receptor targeted agents combined of 9.6 (95% CI 9.1-10.3) months versus 8.6 (95% CI 6.3-9.1) for all men in NPCR. There were little differences in baseline characteristics between men on androgen receptor targeted agents in/ not in PPC.

Dr. Fallara concluded this presentation with the following take-home messages:

  • Time on treatment with abiraterone or enzalutamide in clinical practice was similar or shorter than that in randomized controlled trials
  • These results may be explained by differences in patient characteristics
  • These results suggest that data on the use of abiraterone or enzalutamide for men in PPC are representative for all men on abiraterone or enzalutamide in Sweden.

Presented by: Giuseppe Fallara, MD, IRCCS Ospedale San Raffaele, Vita-Salute San Raffaele University, Division of Experimental Oncology, Unit of Urology, Milan, Italy

Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2021 European Association of Urology, EAU 2021- Virtual Meeting, July 8-12, 2021.

References:

  1. Ryan CJ, Smith MR, de Bono JS, et al. Abiraterone in metastatic prostate cancer without previous chemotherapy. N Engl J Med. 2013;368(2):138-148.
  2. Beer TM, Armstrong AJ, Rathkopf DE, et al. Enzalutamide in metastatic prostate cancer before chemotherapy. N Engl J Med 2014;371(5):424-433.
  3. de Bono JS, Logothetis CJ, Molina A, et al. Abiraterone and increased survival in metastatic prostate cancer. N Engl J Med. 2011;364(21):1995-2005.
  4. Scher HI, Fizazi K, Saad F, et al. Increased survival with enzalutamide in prostate cancer after chemotherapy. N Engl J Med 2012;367:1187-1197.
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