A Phase 2 interventional study of Enzalutamide and Laboratory Biomarker Analysis in Castration-Resistant Prostate Carcinoma, Prostate Carcinoma Metastatic in the Bone and Stage IV Prostate Cancer, sponsored by University of Southern California. Active, not recruiting at 3 sites in United States. Open to male participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-06-03.
Sponsored by University of Southern California · Phase 2, Interventional, and Treatment
This randomized phase II trial studies how well enzalutamide with or without radium Ra 223 dichloride in treating patients with castration-resistant prostate cancer that has spread to other places in the body. Enzalutamide is an androgen receptor inhibitor that may slow down the growth of prostate cancer by blocking the action of the male hormone testosterone and other male hormones called androgens. Radiation therapy uses high energy alpha particles to kill tumor cells and shrink tumors. Enzalutamide with or without radium Ra 223 dichloride may work better in treating patients with castration-resistant prostate cancer.
PRIMARY OBJECTIVES:
I. To evaluate changes in prostate cancer bone involvement induced by enzalutamide alone or in combination with radium Ra 223 dichloride (radium 223), specifically extent of prostate cancer infiltration, androgen receptor (AR) signaling and hormone levels, hematopoietic composition, apoptosis and proliferation.
II. To evaluate the immune activation of enzalutamide alone, or with radium 223.
SECONDARY OBJECTIVES:
I. To describe the adverse event profile for the combination in this patient population.
II. Rate of undetectable prostate specific antigen (PSA) nadir, PSA and alkaline phosphatase changes, rate of symptomatic skeletal events at 12 months, and rate of PSA and radiographic progression at 12 months.
OUTLINE: Patients are randomized to 1 of 2 arms.
ARM I: Patients receive enzalutamide orally (PO) daily on days 1-28. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. Patients also receive radium Ra 223 dichloride intravenously (IV) on day 1. Treatment repeats every 28 days for up to 6 courses in the absence of disease progression or unacceptable toxicity.
ARM II: Patients receive enzalutamide as in Arm I. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity.
After completion of study treatment, patients are followed up every 3 months for 1.5 years.
7,046 studies on the registry are indexed under Prostatic Neoplasms; 1,580 are open to participants now.
This study's enrollment of 30 is below the median of 60 across 5,348 interventional studies indexed under Prostatic Neoplasms.
Browse Prostatic Neoplasms studies →University of Southern California is the lead sponsor of 791 studies on the registry; 136 are open to participants now.
Of its 70 completed or terminated interventional studies of FDA-regulated products, 32 (46%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Castration resistance will be defined as the development of disease progression, defined as one of the following:
Men must have osseous metastases, but the presence of visceral metastases will not exclude patients from participation
Exclusion Criteria:
Prior treatment with ARN-509 or enzalutamide (there is a grace period for men who wish to enroll and who have recently started enzalutamide for the first time but have taken less than 15 days of therapy)
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Absolute neutrophil count (ANC)
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Creatinine clearance (CrCl)
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Washout period
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
TIA (transient ischaemic attack)
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Leptomeningeal disease
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Patients receive enzalutamide PO daily on days 1-28. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. Patients also receive radium Ra 223 dichloride IV on day 1. Treatment repeats every 28 days for up to 6 courses in the absence of disease progression or unacceptable toxicity.
Drug: Enzalutamide · Other: Laboratory Biomarker Analysis · Radiation: Radium Ra 223 Dichloride
Patients receive enzalutamide as in Arm I. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity.
Drug: Enzalutamide · Other: Laboratory Biomarker Analysis
Given PO
Also known as: ASP9785, MDV3100, Xtandi
Correlative studies
Given IV
Also known as: Alpharadin, BAY 88-8223, BAY88-8223, Radium 223 Dichloride, RADIUM CHLORIDE RA-223, Radium-223 Dichloride, Xofigo
Changes in prostate cancer bone involvement
Will be determined by standard pathologic analysis of the biopsies.
Time frame: Up to 1.5 years
Started Nov 2018 (actual). Primary completion is estimated for Dec 2026, 97 months after the start.
Of 610 non-industry phase 2 interventional studies under Prostatic Neoplasms, half reached primary completion within 57 months of starting (the median), counting those still running; a quarter within 39 and three quarters within 86. This study's planned 97 months is above that.
Counting every sponsor, half of 724 studies reached it within 53 months; a quarter within 34 and three quarters within 80.
How these figures are worked out, and which studies are left out of them.
This study is active, not recruiting, as verified in May 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Enzalutamide
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