Docetaxel/Prednisone Versus Docetaxel/Prednisone and Enzalutamide in Castration-Resistant Prostate Cancer

Inclusion Criteria:

Willing and able to provide written informed consent and HIPAA authorization for the release of personal health information.

NOTE: HIPAA authorization may be either included in the informed consent or obtained separately.

Males 18 years of age and above
Histologically or cytologically confirmed adenocarcinoma of the prostate without neuroendocrine differentiation or small cell features
Having documented disease progression on enzalutamide defined by 1 or more of the following criteria:
PSA progression according to PCWG2 criteria with 3 consecutive rising PSA measurements, all collected at least 1 week apart
Radiographic progression in soft tissue or bone by modified RECIST 1.1 for subjects with measurable disease; or
Bone disease progression defined by 2 or more new lesions on 2 consecutive bone scans in the absence of falling PSA
Patients who have not had a bilateral orchiectomy must have a plan to maintain effective GnRG-analogue therapy for the duration of the trial
Serum testosterone level < 50 ng/dL at Screening visit
ECOG PS: 0-1
Throughout the study, male patients and their female partners of childbearing potential must use 2 acceptable methods of birth control (1 of which must include a condom as a barrier method of contraception) starting at screening and continuing throughout the study period and for 3 months after final study drug administration. Two acceptable methods of birth control thus include the following:
Condom (barrier method of contraception even if having sex with a pregnant woman)

One of the following is required:

Established use of oral, injected, or implanted hormonal method of contraception by the female partner
Placement of an intrauterine device (IUD) or intrauterine system (IUS) by the female partner
Additional barrier method: Occlusive cap (diaphragm or cervical/vault caps) with spermicidal foam/gel/film/cream/suppository by the female partner
Tubal litigation in the female partner
Vasectomy or other procedure resulting in infertility (eg, bilateral orchiectomy) for >6 months
Patients must have adequate organ and marrow function as defined below
Leukocytes >3,000/mm3
absolute neutrophil count >1,500/mm3
platelets >100,000/mm3
total bilirubin within normal institutional limits (or <2X the upper limit of normal in those with Gilbert's disease)
AST(SGOT)/ALT(SGPT) <1.5 X institutional upper limit of normal
creatinine within normal institutional limits OR
creatinine clearance* >45 mL/min/1.73 m2 for patients with creatinine levels above institutional normal
Estimated life expectancy of > 6 months
Able to swallow the study drug as prescribed and comply with study requirements

Exclusion Criteria:

Prior treatment with docetaxel-based chemotherapy
Prior treatment with abiraterone acetate
Prior treatment with cabazitaxel
Severe concurrent disease, infection, or co-morbidity that, in the judgment of the Investigator, would make the patient inappropriate for enrollment
Ongoing investigational treatment
Medical conditions such as uncontrolled hypertension, uncontrolled diabetes mellitus, cardiac disease that would, in the opinion of the investigator, make this protocol unreasonably hazardous
Major surgery within 4 weeks of enrollment
Use of an investigational therapeutic agent with 4 weeks of enrollment
History of seizure or any condition that may predispose to seizure.
History of loss of consciousness or transient ischemic attack within 12 months of enrollment
Gastrointestinal disorder affecting absorption (e.g., gastrectomy, active peptic ulcer disease) within last 3 months
Grade > 2 treatment-related toxicity from prior therapy
History of hypersensitivity to polysorbate 80
Any known allergy to the compounds under investigation
Any other condition which, in the opinion of the Investigator, would preclude participation in this trial