Baseline Hormone Levels Appear to Predict Survival in Metastatic, Castration-resistant Prostate Cancer
April 3, 2012
- High hormone levels linked to longer survival regardless of treatment.
- Biomarker provided meaningful method for patient stratification.
- Data should inform future clinical trial design.
CHICAGO — Patients with castration-resistant prostate cancer treated with the androgen inhibitor abiraterone and who had high baseline hormone levels had longer overall survival compared with patients with low hormone levels, according to data presented at the AACR Annual Meeting 2012, held here March 31 - April 4.
If confirmed, these data mean that levels of hormones, specifically adrenal androgens, may provide physicians with another way to predict the efficacy of therapy in patients with metastatic, castration-resistant prostate cancer, according to Charles J. Ryan, M.D., associate professor of clinical medicine and urology at University of California-San Francisco Helen Diller Family Comprehensive Cancer Center in San Francisco, Calif.
“We have identified that patients who have higher levels of androgen compared with those with lower levels have a better prognosis overall and a better prognosis when receiving abiraterone than patients with lower levels of androgens,” said Ryan. “Patients with low hormone levels seem to have a worse prognosis overall; however, they still benefitted significantly from receiving abiraterone as opposed to receiving placebo.”
In the past, this form of prostate cancer was referred to as hormone-refractory prostate cancer. However, this term is no longer used because, in recent years, researchers have discovered that certain drugs, like abiraterone, which are essentially hormone therapies, improve outcomes and survival rates.
In this prospective substudy, Ryan and colleagues evaluated data from a randomized phase III trial that compared abiraterone to placebo and led to the approval of abiraterone. They categorized patients according to high levels or low levels of hormones.
The results indicated that higher baseline hormone levels were associated with significantly higher overall survival in patients regardless of initial treatment compared with low baseline levels. Patients assigned to placebo and who had high hormone levels had nearly 50 percent improvement in survival compared with those assigned to placebo and who had low hormone levels. In addition, abiraterone was associated with longer overall survival compared with treatment with placebo in patients with high and low levels of baseline hormones.
Patients assigned to abiraterone who had high baseline levels of hormones had almost twice the overall survival compared with those with low levels of hormones assigned to placebo.
“We used to think that it was not necessary to measure hormone levels once they were below normal — that was in part due to the fact that we were using insensitive assays,” Ryan said. “However, now we know that they have prognostic and predictive significance and that physicians treating these patients should think about conducting hormone tests.”
According to Ryan, more work is required to determine how these data will inform the standard-of-care management of patients with prostate cancer; however, it is likely that these data will affect the design of future clinical trials.
The study was sponsored by Cougar Biotechnology, which is owned by Johnson & Johnson.
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Founded in 1907, the American Association for Cancer Research (AACR) is the world’s first and largest professional organization dedicated to advancing cancer research and its mission to prevent and cure cancer. AACR’s membership includes 34,000 laboratory, translational and clinical researchers; population scientists; other health care professionals; and cancer advocates residing in more than 90 countries. The AACR marshals the full spectrum of expertise of the cancer community to accelerate progress in the prevention, biology, diagnosis and treatment of cancer by annually convening more than 20 conferences and educational workshops, the largest of which is the AACR Annual Meeting with more than 18,000 attendees. In addition, the AACR publishes seven peer-reviewed scientific journals and a magazine for cancer survivors, patients and their caregivers. The AACR funds meritorious research directly as well as in cooperation with numerous cancer organizations. As the Scientific Partner of Stand Up To Cancer, the AACR provides expert peer review, grants administration and scientific oversight of individual and team science grants in cancer research that have the potential for patient benefit. The AACR actively communicates with legislators and policymakers about the value of cancer research and related biomedical science in saving lives from cancer.
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In Chicago, March 31 - April 4: