Effect of neoadjuvant abiraterone acetate (AA) plus leuprolide acetate (LHRHa) on PSA, pathological complete response (pCR), and near pCR in localized high-risk prostate cancer (LHRPC) Results of a randomized phase II study

SUMMARY: Abiraterone acetate (ZYTIGA®) is a novel, targeted, oral androgen biosynthesis inhibitor that decreases androgen production in the adrenal glands, testes and prostate cancer cells by inhibiting a steroidal enzyme CYP17. This agent, was approved by the FDA in April, 2011 for use in combination with prednisone, for the treatment of patients with metastatic CRPC (Castrate Resistant Prostate Cancer), who have received prior chemotherapy containing docetaxel (TAXOTERE®). Patients with high risk localized prostate cancer do poorly in spite of aggressive local therapies. To improve outcomes in this patient population, the authors conducted a neoadjuvant trial in which patients with localized prostate cancer with high risk features were divided into two groups. The first group (n = 28) was treated with the LHRH analog, LUPRON® (Leuprolide acetate) for 12 weeks, followed by 12 weeks of combination treatment with LUPRON® and ZYTIGA® . The second group (n = 30) received neoadjuvant LUPRON® plus ZYTIGA® for the entire 24 week period. Patients had radical prostatectomies following their neoadjuvant therapy. Fifty eight patients were enrolled and the eligibility criteria included either T3 disease, a Gleason score of ≥7, a prostate-specific antigen (PSA) level ≥20, or a PSA velocity >2 ng/mL/year. Post prostatectomy specimen analysis revealed that patients treated with the combination of LUPRON® plus ZYTIGA® for the entire 24 week period has a complete pathologic response (pCR) or near complete pCR (≤ 5mm residual tumor) rate amounting to 34%. This benefit was seen without significant systemic toxicities. The authors concluded that neoadjuvant androgen deprivation therapy may significantly improve outcomes in high risk patients with localized disease and will need to be studied further. Taplin ME, Montgomery RB, Logothetis C, et al. J Clin Oncol 30, 2012 (suppl; abstr 4521)