How do patterns of progression influence treatment selection after chemohormonal therapy in patients with metastatic hormone sensitive prostate cancer?

e16504 Background: In the CHAARTED and STAMPEDE clinical trials, Docetaxel combined with androgen-deprivation therapy (ADT) increased overall survival in mHSPC patients. Despite the increasing use of this strategy in clinical practice, there is a lack of information about the best treatment choice after progression. Methods: We retrospectively analyzed 96 patients with mHSPC treated with Docetaxel plus ADT in 18 Spanish centers (July 2014 to December 2016). The objectives of the study were to describe baseline and progression characteristics, as well as second-line treatment choice and its outcomes. Results: The median age was 66.7 years. 33.3% patients had visceral metastases at diagnosis and 81% had a Gleason Score 8-10. After a median follow-up of 12.2 months, 35.4% of patients developed castration-resistant prostate cancer (CRPC). The median time to CRPC was 15.4 months. 36.3% of patients had visceral progressive disease. 27 patients received subsequent treatment after progression: 9 (33.3%) were treated with chemotherapy (2 docetaxel, 6 cabazitaxel, 1 carboplatin-etoposide), and 18 (66.6%) received androgen receptor axis-targeted agents (12 enzalutamide, 6 abiraterone). Median progression-free survival was similar with hormonal therapies (4.3 months) than chemotherapy (3.5 months) as second line. Treatment choice was influenced by pattern of progression (visceral vs non visceral) and time to develop CRPC (≤ 12 vs > 12 months). Hormonal therapies were more frequent for non-visceral disease (75% vs 25%) or patients with longer time to develop CRPC (89% vs 11%). Chemotherapy was preferred in patients with visceral progressive disease (83.3% vs 16.7%). In patients with a time to CRPC less than 12 months both treatments were used equally (44.5 vs 55.5%). Conclusions: In our cohort, androgen receptor axis-targeted agents were used more frequently than chemotherapy after progression to chemo-hormonal therapy. Despite the low number of patients that received treatment at progression, our results suggest that the characteristics at the time of progression, such as pattern of progression and time to develop CRPC, could influence treatment choice.