ESK981 in Treating Patients With Metastatic Castrate-Resistant Prostate Cancer

PRIMARY OBJECTIVES: I. To determine the PSA \>= 50% response rate (PSA50) from baseline using the Prostate Cancer Working Group 3 (PCWG3) criteria to pan-VEGFR/TIE2 tyrosine kinase inhibitor CEP-11981 (ESK981) as a single agent in men with castration-resistant prostate cancer (CRPC) who have progressed on enzalutamide (an oral androgen-receptor inhibitor) and/or abiraterone acetate (an androgen synthesis inhibitor). II. To assess the safety and tolerability of ESK981 as a single agent. SECONDARY OBJECTIVES: I. To determine the time to PSA response to ESK981 in metastatic CRPC patients. II. To determine the duration of PSA response to ESK981 in metastatic CRPC patients. III. To determine PSA progression rates and PSA progression free survival (PFS), as defined by the PCWG3 criteria. TERTIARY OBJECTIVES: I. To assess exploratory biomarkers from blood and tumor biopsies. OUTLINE: Patients receive pan-VEGFR/TIE2 tyrosine kinase inhibitor CEP-11981 orally (PO) once daily (QD) for 5 days (Monday-Friday). Treatment repeats for up to 8 weeks in the absence of disease progression or unacceptable toxicity. If treatment is successful after 8 weeks, patients may receive up to 6 months of pan-VEGFR/TIE2 tyrosine kinase inhibitor CEP-11981. After completion of study treatment, patients are followed up periodically.