Patients with metastatic castration-resistant prostate cancer (mCRPC) who are long-term responders (LTR) to the new agent (NA)-based second line: Clinical outcomes and prognostic factors of subsequent treatment with another NA.

Abstract

254 Background: Three NA [abiraterone acetate (AA), cabazitaxel (CABA), or enzalutamide (ENZ)] are able to significantly prolong their overall survival (OS) after docetaxel failure. A quote of pts can obtain a prolonged disease control over 12 months with a second line NA and it is unclear if a clinical benefit may result from a subsequent treatment with another NA. The present study is aimed to assess the clinical outcomes and prognostic factors of subsequent NA treatment in those pts LTR to a second line NA. Methods: We collected data of pts who received sequentially two NAs after DOC. For each pt we recorded the clinical outcome of treatments received after DOC. We consider as LTR pts without progression over 12 months from the start of the NA second line. We assessed the independent prognostic value of a series of third-line baseline covariates, in terms of progression free survival (PFS) and OS by Cox regression analysis. Results: A consecutive series of 476 mCRPC pts received a NA-based second line: AA (261 pts), CABA (151), and ENZ (64): we identified 116 LTR pts (AA 71 – CABA 28 – ENZ 17). All pts received a subsequent NA-based third line: 27 received AA, 59 CABA, and 30 ENZ. Comparing the third-line outcomes of LTR and no-LTR pts , no statistically significant differences were observed in terms of both biochemical and objective response rate, and PFS, while LTR showed a statistically significant longer OS (median 18 vs 11.4 mos; p< 0.0001). The third line OS was statistically significant different (p = 0.01) according to the sequence adopted (Table). At the multivariate analysis , performance status (PS) and the presence of visceral metastases were independent prognostic factors for PFS in third line, while PSA, PS and lactate dehydrogenase were independent prognostic factors for OS. Conclusions: In our experience, NA-based third line is active also in mCRPC LTR population with highest benefit in sequences with CABA and some factors may help in selecting patients with higher probability of achieving a disease control. [Table: see text]