Recent clinical trials have provided evidence that treating metastatic prostate cancer with a combination of abiraterone and androgen-depravation therapy (ADT) significantly improves the survival rate of patients with metastatic or locally advanced prostate cancer.
Approximately one in seven men worldwide are diagnosed with prostate cancer at least once in their life, and so ensuring the right treatment plans are administered is of significant importance for their best chance of survival.
Affecting the prostate gland, a small walnut-shaped gland in the male reproductive system, prostate cancer is the third leading cause of death among men in Canada. On average, there are 58 men diagnosed, and 11 men who die per day in Canada from prostate cancer alone. Several studies have provided significant evidence that androgens, a type of steroid hormone such as testosterone, are required for prostate cancer cells to grow. Therefore, several therapies used in the treatment of prostate cancer target the suppression of androgens; their mode of action is to block the production or effects of testosterone and other male hormones.
The results of a recent multistage, multi-group clinical trial by Parmar, Snydes, and colleagues investigated the effects of a new combination therapy and the results were published in The New England Journal of Medicine. The trial is called, the Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy (STAMPEDE) trial.This therapy consists of abiraterone, a hormone-based chemotherapy which blocks the production of testosterone, and androgen-deprivation therapy(ADT). The study included 1,917 patients who were either recently diagnosed with metastatic or high-risk locally advanced prostate cancer or individuals who had previously been treated with radical surgery or radiotherapy and now relapsing with high-risk features. Participants were randomly assigned in a 1:1 ratio with either the combination therapy (abiraterone and ADT) or ADT alone. The average age of the patients was 67 years old and follow-up was an average of 40 months. The primary outcome of the study was overall survival, which was defined by the researchers as the time from randomization (beginning of treatment) to death from any cause.
In the combination therapy group, a total of 184 deaths were recorded and 248 patients experienced treatment failure, compared to 262 deaths and 535 with treatment failure in the ADT-only group. Overall the use of abiraterone in combination with ADT resulted in a 71% relative improvement in the time to treatment failure. This translated to a difference in overall survival rate of 37%. Majority of deaths recorded were in patients with metastatic disease, however, the results were consistent between patients with both metastatic and nonmetastatic prostate cancer.
These results are promising particularly for men diagnosed with metastatic or locally advanced prostate cancer as this combination therapy including abiraterone offers them an increased overall and failure-free survival rate compared to patients receiving only ADT.
Written by Lacey Hizartzidis, PhD
James ND, de Bono JS, Spears MR, Clarke NW, Mason MD, Dearnaley DP, RitchieAWS, Amos CL, Gilson C, Jones RJ, Matheson D, Millman R, Attard G, Chowdhury S,Cross WR, Gillessen S, Parker CC, Russell JM, Berthold DR, Brawley C, Adab F,Aung S, Birtle AJ, Bowen J, Brock S, Chakraborti P, Ferguson C, Gale J, Gray E,Hingorani M, Hoskin PJ, Lester JF, Malik ZI, McKinna F, McPhail N, Money-Kyrle J,O’Sullivan J, Parikh O, Protheroe A, Robinson A, Srihari NN, Thomas C, WagstaffJ, Wylie J, Zarkar A, Parmar MKB, Sydes MR; STAMPEDE Investigators. Abiraterone for Prostate Cancer Not Previously Treated with Hormone Therapy. N Engl J Med.2017 Jul 27;377(4):338-351. doi: 10.1056/NEJMoa1702900.
Prostate Cancer Statistics. Canadian Cancer Society Website http://www.cancer.ca/en/cancer-information/cancer-type/prostate/statistics/?region=sk. Accessed August 7th, 2017.