Safety and Anti-Tumor Study of Oral EPI-506 for Patients With Metastatic Castration-Resistant Prostate Cancer

The study will consist of 2 parts: Part I (Dose Escalation) and Part II (Dose Expansion). In
Part I, patients will participate in single, multiple, and long-term dosing periods using
EPI-506 to determine safety, pharmacokinetics, the maximum tolerated dose, and preliminary
indications of anti-tumor activity. Part I is an open-label, adaptive 3 + 3 design,
dose-escalation study. Approximately six dose levels of EPI-506 will be studied, beginning at
80 mg/day. Enrolled patients may be allowed to escalate to a subsequent dose cohort after
their initial twelve weeks. Additional patients may be enrolled at any safe dose level prior
to or concurrent with enrolling patients in Part II.

In Part II, 3 patient populations; post-abiraterone metastatic castration-resistant prostate
cancer (mCRPC) but enzalutamide-naïve, post-enzalutamide mCRPC but abiraterone-naïve, and
post-abiraterone and enzalutamide mCRPC will be studied at the recommended Phase 2 dose
(RP2D) determined in Part I over 12 weeks of daily dosing. Approximately 120 patients (40 in
each cohort) will be enrolled.