Efficacy, Safety, Tolerability, And Pharmacokinetics Of Epi-506 (Ralaniten Acetate), A Novel Androgen Receptor (Ar) N-Terminal Domain (Ntd) Inhibitor, In Men With Metastatic Castration-Resistant Prostate Cancer (Mcrpc) Progressing After Enzalutamide And/Or Abiraterone.

5032Background: EPI-506 (ralaniten acetate) is a first-in-class small molecule transcription inhibitor of the AR NTD. Nonclinical studies demonstrated activity against both full length and resistance-related AR species, including AR-v7. Methods: Open-label, single-arm, Phase 1/2 study evaluating EPI-506 administered orally once-daily. The Phase 1 is a 3+3 design to establish the safety, pharmacokinetic (PK) profile, and recommended phase 2 dose of EPI-506. Anti-tumor activity is also evaluated. Inclusion criteria included: mCRPC with progression after ≥1 line of hormonal therapy or chemotherapy, and progression on enzalutamide and/or abiraterone. Results: Eighteen patients (pts) have been enrolled in the dose escalation phase over 5 dose levels (80, 160, 320, 640, 1280 mg). Median age was 71 (range 58-87). Prior treatments included enzalutamide only (N = 7), abiraterone only (N = 2) or both (N = 9). Six pts have had prior chemotherapy. Seven pts have discontinued due to disease progression and 2 pts due t...