The docetaxel-abiraterone acetate sequence compared to the abiraterone acetate-docetaxel sequence in metastatic castration-resistant prostate cancer patients with a response to previous castration superior to 12 months.

Abstract

353 Background: With the approval of the multiple new life-prolonging treatments for men with metastatic castration-resistant prostate cancer (mCRPC), the optimal sequencing of chemotherapy and androgen-receptor (AR) targeting agents remains unclear. Although response duration to castration could influence decision choice for second hormonal therapies, we do not know whether chemotherapy efficacy could be similar to AR targeting agents such as abiraterone acetate (AA). Methods: A retrospective analysis of mCRPC patients treated at Jolimont Hospital is reported. Patients included were castration-resistant PC with a response to castration superior to 12 months. They were treated with sequential docetaxel and AA, in either order. The combined progression-free survival (combined PFS: PFS1 + PFS2) of AA followed by docetaxel is compared to the reverse sequence (docetaxel followed by AA). Baseline characteristics are reported prior to the start of the first agent in the sequence. Results: Forty-two patients who started treatment for mCRPC between January 2013 and February 2017 were identified: 22 were in the docetaxel-AA sequence (Group A) and 20 were in the AA-docetaxel sequence (Group B). The median duration of response to castration was 16 months in Group A and 18 months in Group B. Proportion of Gleason > 8 was higher in group A (60% vs 50%). Visceral or lymph node disease was more important in group A (35% vs 16%). Median pre-treatment PSA was similar in the two groups (27 and 30). In the group A, PFS1 was 9 months and PFS2 was 8 months, resulting in a combined PFS of 17 months (range 5 to 47months). In the group B, PFS1 was 8 months and PFS2 was 7 months, resulting in a combined PFS of 15 months (range 4 to 45 months). Conclusions: We do not observe differences in clinical outcomes based on alternative sequencing of AA and docetaxel in men with mCRPC with a previous response duration to castration longer than 12 months.