GU Cancers 2019 | Updates from the CHEIRON study: docetaxel plus enzalutamide for mCRPC

The CHEIRON study is the first Phase II randomized trial, which assesses the activity of docetaxel plus one of the two available, new androgen receptor targeting agents. This is a Phase II trial, which randomize patients with castration-resistant prostate cancer, as first-line of treatment, and this patient receive the

The CHEIRON study is the first Phase II randomized trial, which assesses the activity of docetaxel plus one of the two available, new androgen receptor targeting agents. This is a Phase II trial, which randomize patients with castration-resistant prostate cancer, as first-line of treatment, and this patient receive the docetaxel alone plus usual prednisone and androgen deprivation therapy, or the same chemotherapy plus enzalutamide. Enzalutamide is given under the standard dose of 160 mg daily for 24 weeks. And docetaxel is administered the standard dose of 75 mg course every 3 weeks for eight courses.

The main primary point of the study is the rate of patients without progression disease according to Prostate Cancer Working Group 2, at the end of the chemotherapy. We have other secondary points, such as objective response rate, biochemical response rate, overall survival, progression-free survival, overall progression-free survival, or safety and pain and quality of life.

The target is to detect a difference between the standard treatment and the experimental arm of 15% in terms of rate of patients without progression. The trial meets the primary point since the rate of patients without progression of disease at 6 months after the first docetaxel administration was 89% in the experimental arm compared to 73% in the standard arm. This is statistically significant and corresponds to a relative increase of the progression-free response of 20%. And these correspond the number needed to treat of 6.19.

Also, in terms of progression-free survival, there was an advantage in favor of the experimental arm, since the median progression-free survival for the experimental arm was 10.1 months compared to 9.1 months of the standard arm. This difference was statistically significant and corresponded to a reduction of a risk of progression of 29%. This trial confirm the data, the combination of docetaxel and enzalutamide is safe and feasible. Although, the grade three toxicities in the experimental arm compared to the standard arm in terms of febrile neutropenia, fatigue, and skin-toxicity. But, in my opinion, this is a combined treatment which in prospective future may be a major opportunity for our patients.