Study Overview
Objective. To evaluate the efficacy of cabazitaxel compared to androgen-signaling–targeted inhibitors (ASTIs) in patients with metastatic castration-resistant prostate cancer who have received docetaxel and have progressed within 12 months of treatment with either abiraterone or enzalutamide.
Design. The CARD trial was an international, randomized, open-label phase 3 trial conducted across 13 European countries.
Setting and participants. Eligible patients were 18 years of age or older; had metastatic castration-resistant prostate cancer previously treated with docetaxel; and had disease progression during 12 months of treatment with abiraterone or enzalutamide. All patients had histologically proven prostate cancer, castrate levels of serum testosterone, and disease progression, defined by at least 2 new bone lesions or rising prostate-specific antigen (PSA) level. A total of 255 patients underwent randomization between November 2015 and November 2018, with 129 assigned to receive cabazitaxel and 126 patients assigned to receive an ASTI, 58 of whom received abiraterone and 66 of whom received enzalutamide. Patients who had received an ASTI in the setting of castrate-sensitive metastatic prostate cancer were included.
Intervention. Patients were randomized in a 1:1 fashion to receive either cabazitaxel or abiraterone or enzalutamide. Patients receiving cabazitaxel 25 mg/m2 intravenously every 3 weeks also received oral prednisone daily and primary prophylactic granulocyte-colony stimulating factor. Patients assigned to receive an ASTI received abiraterone 1000 mg orally daily with prednisone 5 mg twice daily or enzalutamide 160 mg daily. Patients in the ASTI group who had progressed on abiraterone were assigned to enzalutamide, and alternatively, those on enzalutamide were assigned to abiraterone. Patients were treated until 1 of the following occurred: imaging-based disease progression, unacceptable toxicity, or advancing to an alternative therapy.
Main outcome measures. The primary endpoint was imaging-based progression-free survival, which was defined as the time from randomization until objective tumor progression, progression of bone lesions, or death. The secondary endpoints were overall survival, progression-free survival, PSA response, tumor and pain responses, a new symptomatic skeletal event, and safety.
Results. The median follow-up was 9.2 months. Imaging-based disease progression or death from any cause occurred in 95 (73.6%) participants in the cabazitaxel group, as compared to 101 (80.2%) who were assigned to receive an ASTI. The median imaging-based progression-free survival was 8.0 months in the cabazitaxel group and 3.7 months in the abiraterone/enzalutamide group. The median duration of treatment was longer in those receiving cabazitaxel (22 vs 12.5 weeks). The primary reason for treatment discontinuation was disease progression (in 43.7% of patients receiving cabazitaxel and 71% receiving an ASTI) or an adverse event (19.8% and 8.9%, respectively).
The trial’s secondary endpoints demonstrated improved outcomes in the cabazitaxel group compared to the abiraterone/enzalutamide group. There were 70 deaths (54.2%) in the cabazitaxel group and 83 (65.9%) in the ASTI group. Both the median overall survival (13.6 months in the cabazitaxel group and 11 months in the ASTI group) and the median progression-free survival (4.4 months and 2.7 months, respectively) were improved in those who received cabazitaxel. There was a 50% or greater reduction in the PSA level from baseline in 35.7% of the cabazitaxel group and 13.5% of the ASTI group.