Early Use of Abiraterone in Hormone-Sensitive Advanced Prostate Cancer Recommended

Highlights:

• Abiraterone is a drug that blocks the production of androgens
• It is used along with prednisone for the treatment of prostate cancer after the cancer becomes resistant to standard androgen-deprivation therapy (ADT)
• New studies suggest that it may improve survival when used earlier along with ADT, even when the cancer is sensitive to ADT, or when it is being treated for the first time

Recent studies published in the New England Journal of Medicine and presented at the 2017 ASCO Annual Meeting in Chicago could pave the way for new guidelines regarding the use of abiraterone in the treatment of advanced prostate cancer.

Prostate cancer is common in older men. It can spread locally to lymph nodes, as well as to distant sites of the body like the bone, lung, liver and brain, with serious consequences.

Prostate cancer is treated with surgery, radiation, chemotherapy and hormonal therapy. Since hormones like testosterone and dihydrotestosterone, which are chemically androgens, promote the growth of prostate cancer, prostate cancer benefits from androgen-deprivation therapy. Androgen deprivation can be brought about either by surgical removal of the testes or medications like leuprolide and goserelin. In due course of the cancer, patients stop responding to androgen-deprivation treatment and require other therapeutic options.

Abiraterone acetate Abiraterone acetate is a drug that is emerging as a possible vital addition to the androgen-deprivation therapy for advanced prostate cancer. Abiraterone prevents the production of androgens in the body, and is currently approved along with the corticosteroid prednisone for patients with advanced prostate cancer, who do not respond to androgen-deprivation therapy. Thus, abiraterone is currently being used only when the standard hormonal treatment fails.

The Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy (STAMPEDE) is a large trial which evaluated the addition of treatments for prostate cancer that has locally advanced or spread to distant sites in patients who did not receive prior hormonal treatment. It has come up with several important findings which, if introduced into clinical practice, could possibly improve the survival of patients with advanced prostate cancer.

The STAMPEDE study compared the use of ADT plus abiraterone and prednisolone, to the use of ADT alone for a period of two years or until disease progression. The study included patients who had localized disease as well as those in whom the cancer had spread, and who may have undergone surgery or radiotherapy. Fifty-two percent patients had metastatic cancer, that is, cancer that had spread to other sites of the body. Radiotherapy was administered along with hormonal treatment as and if necessary. The researchers found that, with respect to the group that received the standard treatment, the group taking abiraterone experienced:

• An improvement in overall survival by 37%
• An improvement in the failure-free survival by 71%
• A reduction in the symptomatic skeletal events by 55%
• More cardiovascular and liver related-side effects, with 47% patients in the abiraterone group and 33% patients in the standard treatment group suffering serious adverse effects with grades 3 to 5

The LATITUDE Trial, conducted in 34 countries, evaluated the effects of abiraterone and prednisone along with ADT as opposed to ADT with placebos in the treatment of newly diagnosed metastatic, hormone-sensitive prostate cancer, that is, in cases where the patient did not receive any earlier treatment. The researchers found that as compared to the group administered only ADT, the group taking abiraterone and prednisone along with ADT:

• Had an overall survival of 66% at the end of 3 years while the comparison group registered an overall survival of 49%
• Had a median radiographic progression free-survival in patients of 33 months, as compared to 14.8 months in the control group
• Showed slower progression of other parameters assessed, like pain and next symptomatic skeletal event, and the need for chemotherapy and subsequent prostate cancer therapy
• More commonly caused side effects of high blood pressure, low blood potassium levels and increase in liver enzymes

Thus, the earlier use of abiraterone, along with androgen-deprivation therapy, instead of after it, if approved, could benefit hundreds of men with advanced prostate cancer.

References:

1. James ND et al. Abiraterone for Prostate Cancer Not Previously Treated with Hormone Therapy. NEJM; DOI: 10.1056/NEJMoa1702900
2. Fizazi K et al. Abiraterone plus Prednisone in Metastatic, Castration-Sensitive Prostate Cancer. NEJM; DOI: 10.1056/NEJMoa1704174

Source: Medindia