ASCO 2018: Abiraterone Acetate and Prednisone, AAP Plus Degarelix, and Degarelix Alone for Patients with Biochemically-Recurrent Prostate Cancer Following Radical Prostatectomy

Chiago, IL (UroToday.com) Men with short intervals to PSA failure or fast PSA doubling times after prostatectomy or radiation therapy have increased incidence of distant metastases and prostate specific mortality1,2.   In a cohort of 8,669 men treated with surgery or radiation, men with a PSA doubling time of less than 3 months had a 20 fold increased risk of prostate cancer specific mortality compared with me with a doubling time greater than 3 months3. PSA recurrence has been reported in up to 30% of patients following prostatectomy, most of whom recur in the first five years4. In this setting, combination anti-androgen therapy may have an opportunity to eliminate all disease in a low volume state, potentially providing an opportunity for cure.

In this three-arm study, 120 patients following radical prostatectomy ± salvage radiotherapy were randomized to either abiraterone acetate and prednisone (AAP), AAP plus degarelix (AAP+D), or degarelix (D) alone. Inclusion criteria included rising PSA ≥1.0 ng/ml, doubling time ≤9 months, no evidence of metastatic disease on CT/bone scan, and a testosterone level greater than 150 mg/dL.

Patients were treated for 8 months with their assigned therapy and then therapy was stopped. The primary endpoint was total number of patients with undetectable PSA with a testosterone above 150 at 18 months. The second endpoint was those with an undetectable PSA at 8 months.

With regards to the primary endpoint, there was no significant difference between the three arms (AAP – 5%, AAP+D – 16%, D – 13%) – the authors note that “these results set a benchmark for future trials that 10-15% of pts can achieve this outcome”. There was also no significant difference in the secondary outcome (See table 1). 



For future studies, it may be interesting to investigate whether or not quality of life was significantly different between these three cohorts, as the primary and secondary outcomes did not significantly differ. Also, it would be interesting to see if there is any difference for metastasis free survival – a potential surrogate for overall survival which is being described in several abstracts during this ASCO meeting. Additionally, it would be interesting to examine the difference in cost of treatment for each arm over the 8 months of therapy.


Presented By: Karen A. Autio, MD. Memorial Sloan Kettering Cancer Center

Written By: Jason Zhu, MD. Fellow, Division of Hematology and Oncology, Duke University @TheRealJasonZhu

Referenes:
1. Freedland SJ, Humphreys EB, Mangold LA, et al. Risk of prostate cancer–specific mortality following biochemical recurrence after radical prostatectomy. JAMA 2005;294:433-9.

2. Buyyounouski MK, Pickles T, Kestin LL, Allison R, Williams SG. Validating the Interval to Biochemical Failure for the Identification of Potentially Lethal Prostate Cancer. Journal of Clinical Oncology 2012;30:1857-63.

3. D’Amico AV, Moul JW, Carroll PR, Sun L, Lubeck D, Chen M-H. Surrogate End Point for Prostate Cancer–Specific Mortality After Radical Prostatectomy or Radiation Therapy. JNCI: Journal of the National Cancer Institute 2003;95:1376-83.

4. Caire AA, Sun L, Ode O, et al. Delayed Prostate-specific Antigen Recurrence After Radical Prostatectomy: How to Identify and What Are Their Clinical Outcomes? Urology 2009;74:643-7.

J Clin Oncol 36, 2018 (suppl; abstr 5016)