ORLANDO—Adding docetaxel to androgen deprivation therapy (ADT) does not improve overall survival (OS) in men with hormone-naïve metastatic prostate cancer (mPCa), according to an updated analysis from the phase 3 GETUG-15 clinical trial (Abstract 140) presented during the 2015 Genitourinary Cancers Symposium.1
The findings are inconsistent with recent E3805 trial results that suggested a survival benefit for ADT plus docetaxel.
“With longer follow-up, the addition of docetaxel to ADT did not significantly improve OS in patients with hormone-naïve metastatic prostate cancer,” reported lead study author Gwenaelle Gravis, MD, PhD, of the Department of Medical Oncology at the Institut Paoli Calmettes, in Marseille, France.
“Combining docetaxel and ADT significantly improved clinical and biological progression-free survival (PFS) over ADT alone.”
“In the retrospective analysis using aligned definition of volume of metastasis as E3805, the HVD outcomes were similar to the E3805 trial for ADT alone and there was a non-significant 4 months increase in OS with ADT+D, in this underpowered subset. … Recently, the E3805 trial reported a survival benefit for (ADT+D) in high volume disease (HVD) patients, whereas the GETUG-15 trial did not demonstrate a survival improvement among a less-selected group of patients with hormone-naïve metastatic PCa.”
The authors analyzed OS and retrospectively assessed tumor volume using a definition of high volume disease (HVD) of 4 or more bone lesions and 1 or more lesion in any bony structure beyond the spine or pelvis, or the presence of visceral metastases, Dr. Gravis reported.
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At a median follow-up of 82.9 months, in the updated analysis, median OS for patients receiving ADT alone was 46.5 months vs 60.9 months for patients receiving ADT+D, but this difference was not statistically significant (hazard ratio [HR]=0.9; 95% CI:0.7,1.2; not significant). Gravis reported.
Salvage docetaxel was very frequent (80%) in the GETUG-15 trial, she noted.
The extent of metastases was an independent prognostic factor for OS, she noted as a potential factor in explaining the discrepant OS outcomes for GETUG-15 and E3805. Other trials will be reported soon, she noted, which might clarify the relationship between ADT+D and OS.
PFS was significantly longer with the addition of docetaxel, she added: 12.9 months vs 22.9 months (clinical PFS HR=0.7; 95% CI:0.6,0.9; P=0.0021).
- Gravis G, Boher JM, Joly F, et al. Androgen deprivation therapy (ADT) plus docetaxel (D) versus ADT alone for hormone-naïve metastatic prostate cancer (PCa): Long-term analysis of the GETUG-AFU 15 phase III trial. 2015 Genitourinary Cancers Symposium. Abstract 140.