Background: Limited real-world data are available on tx sequence for patients (pts) with metastatic hormone-sensitive PC (mHSPC) treated with androgen deprivation therapy (ADT) plus docetaxel (D) or abiraterone (A) who progress to metastatic castrate-resistant prostate cancer (mCRPC). Methods: VA electronic medical records were used to retrospectively analyze 240 men treated for mHSPC with ADT and D (n=208; selected to be overrepresented) from 07/2014-08/2018 or ADT and A (n=32) from 12/2016-09/2018 and receiving at least one tx after progressing to mCRPC. Results: For D and A cohorts respectively, median age at mHSPC diagnosis was 65.2 and 70.8 yrs; 62% and 77% were white; 98% and 100% had bone metastases (mets), 40% and 34% had lymph node mets, 21% and 16% had lung mets, and 20% and 6% had liver mets; median follow-up after ADT start was 2.2 and 1.4 yrs. Pts in D and A cohorts had 56% and 36% low, 33% and 45% intermediate, and 11% and 19% high Halabi risk scores at mCRPC, respectively. Among all pts, max mCRPC tx lines was 6; 106 (44%) had only one line, 71 (30%) had two lines, and 63 (26%) pts had ≥ three lines. Across all mCRPC tx lines, 71 (30%) received a taxane at some point (47 D, 40 cabazitaxel [C]). Txs for first and second line mCRPC are shown in the Table. For D pts who received androgen-receptor targeted agents (ARTA) as first mCRPC tx and received any second mCRPC tx, 70 (62%) were treated with back-to-back ARTA. For A pts, 25 (78%) received back-to-back ARTA as first mCRPC tx. Conclusions: Most pts received ARTA as first mCRPC tx, and a large proportion of pts were treated with back-to-back ARTA. Longer follow-up is needed to assess which sequences are associated with optimal outcomes.

A: abiraterone; C: cabazitaxel; D: docetaxel; E: enzalutamide; R: radium-223; S: sipuleucel-T