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Abiraterone and Enzalutamide Thwart Prostate Cancer Pain


AT THE EUROPEAN SOCIETY FOR MEDICAL ONCOLOGY CONGRESS


Vitals

Major Findings: Abiraterone acetate reduced opiate use by 19%, and enzalutamide the risk of pain progression by 44%.

Data Source: Two randomized phase III trials reported on pain outcomes: COU-AA-302 involved 1,088 chemotherapy-naive and men with metastatic, castration-resistant prostate cancer (mCRPC) treated with abiraterone acetate plus prednisone or prednisone plus placebo; AFFIRM involved 1,199 chemotherapy-experienced mCRPC patients comparing enzalutamide vs. placebo.

Disclosures: Ortho Biotech Oncology Research & Development sponsored the COU-AA-302 study. AFFIRM was supported by Medivation and Astellas Pharma. Dr. Fizazi has participated in advisory boards for Medivation and Astellas Pharma. Dr. Basch reported no conflicts of interest in relation to the COU-AA-302 study. Dr. Efstathiou had no disclosures.

VIENNA – Two recently approved drugs – abiraterone acetate and enzalutamide – led to better pain control in reports from separate clinical trials conducted among men with metastatic castration-resistant prostate cancer.

Abiraterone (Zytiga) reduced opiate use by 19%, the average pain intensity score by 19%, and the impact of pain on daily lives by 21% for chemotherapy-naive patients, according to new data from the phase III COU-AA-302 study.

Hazard ratios favoring abiraterone were 0.817 for the median time to opiate use, 0.817 for the average pain intensity, 0.792 for pain interference, and 0.845 for worst pain intensity. Abiraterone was given in combination with prednisone during the trial and compared with placebo plus prednisone.

New data from the AFFIRM trial show that enzalutamide (MDV3100, Xtandi) had a beneficial impact on cancer-related pain in men with previously treated metastatic castrate-resistant prostate cancer (mCRPC). Notably, investigators reported a 44% reduction in pain progression vs. placebo (HR, 0.564; P less than .0001).

These findings from both trials were presented at the European Society for Medical Oncology (ESMO) congress. In the United States, the Food and Drug Administration has approved both androgen-signaling inhibitors for second-line treatment of mCRPC after docetaxel (Taxotere) therapy has failed – abiraterone in April 2011 and enzalutamide in August 2012.

Abiraterone: New Data From the COU-AA-302 Trial

"Pain is an important, often feared, and debilitating complication of metastatic, castration-resistant prostate cancer, which can affect up to half of men with metastatic disease," said Dr. Ethan Basch, who presented the COU-AA-302 patient-reported outcome data.

"Understanding the impact of abiraterone and other agents on pain provides valuable information for decision makers," Dr. Basch, of Memorial Sloan-Kettering Cancer Center in New York, added.

Abiraterone’s pain-reducing effects add to benefits reported at American Society of Clinical Oncology (ASCO) annual meeting earlier in the year, where the results of the second planned interim analysis showed it significantly delayed progression and the initiation of chemotherapy in the targeted population.

Trial participants were chemotherapy-naive men with asymptomatic or mildly symptomatic, mCRPC; 546 were randomized to treatment with abiraterone plus prednisone and 542 to placebo plus prednisone. The median treatment duration in each arm was 13.8 months and 8.3 months, respectively.

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