Combo Therapy in Prostate Cancer Yields 13.6-Month Survival Boost

Adding chemotherapy to hormone therapy in men with metastatic hormone-sensitive prostate cancer improved median overall survival by 13.6 months compared with men treated with the standard regimen of hormone therapy alone. These results, after a 28.9-month follow-up, were published last week in the New England Journal of Medicine.

Men with metastatic prostate cancer have traditionally been treated with hormone therapy initially, while chemotherapy was saved for patients who progressed to castration-resistant disease.

The CHAARTED (Eastern Cooperative Oncology Group [ECOG] E3805) study is now the first to demonstrate that adding docetaxel chemotherapy upfront in prostate cancer offers a survival benefit. Men who received the combination therapy had a median overall survival of 57.6 months compared with 44 months in the androgen-deprivation therapy (ADT) arm (hazard ratio [HR], 0.61;  P < .001).

The initial results from this phase III clinical trial were presented at the 2014 American Society of Clinical Oncology (ASCO) Annual Meeting by study author Christopher Sweeney, MBBS, associate professor of medicine at Harvard Medical School in Boston.

The ECOG E3805 CHAARTED trial randomized 790 men (median age = 63), to either a dose of 75 mg/m² docetaxel every 3 weeks for 6 cycles plus ADT or to ADT alone. The median time to any kind of disease progression was 20.2 months in the combination therapy arm compared with 11.7 months in the control arm (HR, 0.61; P < .001). The rate of patients with a prostate-specific antigen (PSA) level of less than 0.2 ng/mL at 12 months was 27.7% in the combination arm compared with 16.8% in the ADT monotherapy arm (P < .001).

Side effects were more frequent and severe in the combination therapy arm. The rate of grade 3/4 febrile neutropenia was 6.2%, grade 3/4 infection with neutropenia was 2.3%, and the rate of grade 3 sensory neuropathy and motor neuropathy were both 0.5%.

“The clinical benefit at this early analysis was more pronounced among patients with a higher burden of disease,” stated Sweeney and co-study authors in their discussion.

Another even larger study, the STAMPEDE (Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy) trial, presented at the 2015 ASCO Annual Meeting, also showed a survival benefit for chemotherapy combined with ADT for newly diagnosed prostate cancer patients after a median follow-up of 42 months.

The National Comprehensive Cancer Network already includes upfront chemotherapy as a therapy option for newly diagnosed prostate cancer based on both the publication of the STAMPEDE trial and the initial presentation of the CHAARTED study in 2014.