Sequential administration of new agents (NAs) after docetaxel (DOC) in metastatic castration-resistant prostate cancer (mCRPC) patients (pts): Impact of disease control (DC) duration in second line on the subsequent line outcomes.

Abstract

210 Background: Abiraterone acetate (AA), cabazitaxel (CABA), and enzalutamide (ENZ) are NAs which demonstrated their efficacy in mCRPC pts who have previously treated with DOC. Unfortunately all pts develop a resistance to these drugs and eventually show a progression of disease. Since the androgen receptor machinery remains the ultimate target of NAs in mCRPC post-DOC, some mechanisms of resistance could be common to all NAs. To date, NAs are sequentially administered in the hope of obtaining a cumulative survival benefit. To date it is unknown if the DC duration influence the outcomes of the subsequent treatments. The present study was aimed to retrospectively assess this issue in a large series of mCRPC pts. Methods: We recorded the clinical outcomes of all treatments received after DOC. For the study purpose, we categorized the pts according to the duration of DC (absence of progression) during NA-based second line: DC ≤ 3 mos (primary resistance – PRe); DC from 3.1 to 11.9 mos (intermediate sensitivity – IS); DC ≥ 12 mos (long term disease control – LTDC). Results: A consecutive series of 291 mCRPC pts, median age 71 yrs (46-91), with bone (88%), nodal (53%) or visceral (18%) mets, was collected. All pts received a NA-based as second line after DOC: 160 (55%) received AA, 99 (33%) CABA and 32 (11%) ENZ. PRe was observed in 56 pts (23 AA – 25 CABA – 8 ENZ), IS in 178 (101 AA – 58 CABA – 19 ENZ), LTDC in 57 (36 AA – 16 CABA – 5 ENZ). The third-line clinical outcomes are detailed in the table. Conclusions: From this data, it appears that DC duration may be a prognostic factor, as a probable result of pts/disease selection. In fact, pts progressing more than 12 mos from the start of NA-based second line appear to have more probabilities to live longer, compared to pts progressing earlier, when they receive another NA-based third line therapy. [Table: see text]