Abiraterone Prednisone and Hormonal Therapy Before and During Radiation Therapy in Localized Prostate Cancer

This phase II trial studies the side effects and how well abiraterone acetate, prednisone, and leuprolide acetate or goserelin before and during radiation therapy works in treating patients with localized or locally advanced prostate cancer. Androgens can cause the growth of prostate cancer cells. Antihormone therapy, such as abiraterone acetate, leuprolide acetate, and goserelin, may lessen the amount of androgens made by the body. Radiation therapy uses high-energy x-rays to kill tumor cells. Giving abiraterone acetate and leuprolide acetate or goserelin before or together with radiation therapy may be an effective treatment for prostate cancer.

PRIMARY OBJECTIVES: I. To evaluate the safety of abiraterone (abiraterone acetate) and prednisone with luteinizing hormone-releasing hormone agonist given as neoadjuvant and concurrent therapy with external beam radiation in patients with localized prostate cancer. II. To determine whether pharmacologic suppression of the prostatic androgen axis by inhibition of androgen production with abiraterone can decrease tissue androgen levels to below those observed with gonadotropin-releasing hormone (GnRH) agonist suppression of testicular androgens. SECONDARY OBJECTIVES: I. To determine whether treatment with abiraterone acetate with luteinizing releasing hormone agonist will be more effective than agonist with bicalutamide in inducing inhibition of androgen-regulated gene expression and increased apoptotic cell death as assessed by immunohistochemistry, complementary deoxyribonucleic acid (cDNA) microarray analysis and reverse transcription-polymerase chain reaction (RT-PCR). II. To evaluate time to prostate-specific antigen progression in patients treated with GnRH agonist with abiraterone acetate. OUTLINE: Patients receive abiraterone acetate orally and prednisone once daily for 24 weeks. Patients also receive leuprolide acetate or goserelin in weeks 1 and 13. Patients undergo external beam radiotherapy starting in week 15 for 8.5 weeks. Treatment continues in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up every 3 months for 5 years.