GETUG-AFU 15 sought to improve outcomes in metastatic hormone-naive prostate cancer, but the study failed its primary objective,” noted formal discussant Eric J. Small, MD, of the University of California, San Francisco.

In the overall analysis of this previously published trial, with no enrichment for any group, there was a 14-month difference in overall survival, which did not reach statistical significance, he reminded listeners.

However, the CHAARTED study showed a highly statistically significant 13.6-month difference in survival with the addition of docetaxel to hormone therapy. This trial had more patients, and the benefit of early docetaxel was driven by high-volume patients, with no benefit in low-volume patients.

Potential reasons for the overall survival difference between the two trials include one-third fewer high-volume patients in the GETUG-AFU 15 trial and no enrichment for high-volume patients, Dr. Small said.

“The GETUG-AFU 15 trial is underpowered, but results are directionally consistent with the ECOG CHAARTED trial, and the discrepancy between these trials can be explained,” he stated.

“In summary, high-volume disease does worse than low-volume disease and should be treated with androgen-deprivation therapy plus docetaxel. At this time, low-volume disease in hormone-sensitive prostate cancer should not be treated with docetaxel. Identification of biomarkers to predict which patients may benefit from docetaxel is a research priority,” Dr. Small said.

Dr. Small looks forward to the results of the CALGB 90203 trial, which is comparing prostatectomy vs neoadjuvant androgen-deprivation therapy plus docetaxel followed by prostatectomy and includes correlative analysis of molecular tissue with clinical outcomes. ■

Disclosure: Dr. Small reported no potential conflicts of interest.