Genitourinary Cancer

SS 28 - GU 3 - New Insights Into Treatment Intensification Strategies for Prostate Cancer

203 - Two Year Outcomes of Short-Term Potent Androgen Blockade and Definitive Radiation for Intermediate to High Risk Localized Prostate Cancer

Tuesday, October 23
3:35 PM - 3:45 PM
Location: Room 007 A/B

Two Year Outcomes of Short-Term Potent Androgen Blockade and Definitive Radiation for Intermediate to High Risk Localized Prostate Cancer
B. F. Koontz1, K. E. Hoffman2, P. Healy1, D. J. George1, M. R. Harrison1, T. Zhang1, W. R. Lee1, W. R. Berry1, T. J. Pugh3, L. Bratt1, B. Hobbs4, S. Halabi1, P. G. Corn4, A. Armstrong1, K. Shobe1, B. Tojong1, B. Thornburg1, K. Brummer1, and D. Allen1; 1Duke Cancer Institute, Durham, NC, 2Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, 3University of Colorado, Aurora, CO, 4The University of Texas MD Anderson Cancer Center, Houston, TX

Purpose/Objective(s): Studies of combination ADT and RT have shown benefit to long-term ADT in high risk prostate cancer; however years of ADT carry significant morbidity. Recent randomized trials show improved survival in advanced prostate cancer by adding abiraterone acetate/prednisone (AAP) to ADT to provide a potent complete androgen blockade. We hypothesized that such a combination of androgen inhibition in men with aggressive but localized PC would synergize with definitive RT to provide biochemical control with a 6 month ADT course.

Materials/Methods: This prospective phase 2 single arm clinical trial was performed at two sites within the Department of Defense PCCTC (NCT01717053). Eligibility included 2+ intermediate or 1 high NCCN risk factors and no metastatic disease. Men received 6 months of ADT concurrently with 1000mg abiraterone acetate and 5mg prednisone daily. RT to prostate/SV (78 Gy) was initiated at week 9. Primary endpoint was PSA <0.1 ng/ml at 1 year. Secondary objectives included biochemical PFS, PSA nadir, testosterone recovery, toxicity, and patient-reported QOL.

Results: 37 men were enrolled, with 33 completing the full course of treatment (4 patients halted within first 4 weeks of therapy for personal preference (N=3) or renal artery stenosis). Median age was 65 years. 66% were cT1, 46% Gleason 8-10, 42% Gleason 4+3=7, and baseline PSA was 7.3ng/ml (range 1.4-18.5). Median follow-up is 24 months. Acute grade 3 toxicities (32%) were all related to abiraterone acetate (hypertension, lab abnormalities) and managed with medication hiatus (32%) and medical therapy; no G4+ or unexpected toxicities were observed. 78% of patients nadired to 90).

Conclusion: In men with aggressive prostate cancer (2+ intermediate or 1 high risk factors), utilizing short-term ADT/abiraterone acetate/prednisone with definitive RT promotes a high rate of testosterone recovery with excellent PSA control at 1 and 2 years.

Author Disclosure: B.F. Koontz: Employee; Duke University Medical Center. Research Grant; Janssen Services LLC. Advisory Board; Blue Earth Diagnostics, Bayer Pharmaceuticals. Travel Expenses; ASTRO. Committee Co-chair; IHE-RO. Committee member; ASTRO. K.E. Hoffman: Independent Contractor; Vanderbilt University. P. Healy: None. D.J. George: Honoraria; Bayer, BIOPHARM, Medivation, Novartis, Sanofi. Consultant; Acceleron Pharma, Astellas Pharma, Bristol-Meyers, Celgene, Dendreon, Exelixis, Genentech, GlaxoSmithKline, Innocrin, Janssen, Merck, Myovant Sciences, Novartis, Pfizer. M.R. Harrison: Research Grant; Argos Therapeutics, Bristol-Myers Squib, Medivation, Pfizer. Consultant; Bayer, Exelixis, Genentech, Sanofi. T. Zhang: Research Grant; Acerta, Janssen, Merrimack, Pfizer, Stem CentRx. Consultant; Bayer, G1 Therapeutics. W. Lee: Independent Contractor; ASTRO. W.R. Berry: None. T.J. Pugh: Travel Expenses; Augmenix. S. Halabi: Consultant; Dendreon, Eisai, Genentech, Sanofi, Tokai Pharmaceuticals. P.G. Corn: Research Grant; Exelixis, Sanofi. A. Armstrong: Research Grant; Dendreon, Janssen Oncology, sanofi, Bayer, Medivation, Novartis, Pfizer, Active Biotech, Astellas, Gilead Sciences. B. Tojong: None. B. Thornburg: None.

Bridget Koontz, MD

Disclosure:
Employment
Duke Cancer Institute: Associate Professor: Employee; Duke University Medical Center: Assistant Professor: Employee

Compensation
ASTRO: Travel Expenses; Bayer Pharmaceuticals: Advisory Board; Blue Earth Diagnostics: Advisory Board; Janssen Services LLC: Research Grants

Leadership
AAPM: Committee Co-Chair; ASTRO: Committee member; IHE-RO: Committee Co-chair

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