964TiP - ARN-509 in men with metastatic castration-resistant prostate cancer (CRPC)

Date 29 September 2012
Event ESMO Congress 2012
Session Poster presentation I
Topics Drug Development
Prostate Cancer
Presenter Dana E. Rathkopf
Authors D.E. Rathkopf1, E.S. Antonarakis2, N.D. Shore3, R. Tutrone4, J. Alumkal5, C.J. Ryan6, M. Saleh7, R. Hauke8, E. Chow-Maneval9, H.I. Scher1
  • 1Medicine, Memorial Sloan-Kettering Cancer Center, New York/US
  • 2Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore/US
  • 3Urology, Carolina Urologic Research Center, Myrtle Beach/US
  • 4Urology, Chesapeake Urology Research Associates, Baltimore/US
  • 5Medicine, Oregon Health & Science University Knight Cancer Institute, Portland/US
  • 6University of California, San Francisco, 94115 - San Francisco/US
  • 7Medicine, Georgia Cancer Specialists, Atlanta/US
  • 8Medicine, Nebraska Cancer Specialists, Omaha/US
  • 9Clinical Development, Aragon Pharmaceuticals, San Diego/US

Abstract

Background

ARN-509 is a novel second-generation anti-androgen that binds directly to the ligand-binding domain of the androgen receptor, impairing nuclear translocation and DNA binding. The Phase II portion of a multicenter Phase I/II study is evaluating the activity of ARN-509 in 3 distinct patient populations of men with CRPC: 1) non-metastatic treatment-naïve CRPC; 2) mCRPC treatment-naïve (tx-naïve); and 3) mCRPC abiraterone acetate pre-treated (AA). Preliminary results for the 2 cohorts of patients with metastatic CRPC are presented here.

Methods

All patients had metastatic CRPC with progressive disease based on rising PSA and/or imaging. No prior chemotherapy for metastatic prostate cancer was allowed. Patients on the AA pre-treated cohort had to have been treated with AA for at least 6 months. All patients received ARN-509 at the recommended Phase II dose of 240 mg/day (Rathkopf et al, GU ASCO 2012). The primary endpoint was PSA response rate at 12 weeks according to the Prostate Cancer Working Group 2 Criteria in each of the treatment groups. Secondary endpoints included safety, time to PSA progression and objective response rates. PSA assessments were collected every 4 weeks and tumor imaging was performed every 16 weeks.

Results

To date, 32 patients have been enrolled: 25 on the tx-naïve and 7 on the post-AA cohorts, respectively. The combined median age was 67 (range 51-91) and at baseline, patients presented with ECOG performance status 0 (55%), Gleason Score 8-10 (54%), and median PSA of 14.7 (tx-naïve) and 69.6 (post-AA) ng/mL. All patients received prior treatment with a LHRH analog with or without a first-generation anti-androgen. At a median treatment duration of 16 weeks, 4 patients discontinued the study due to disease progression, 2 in each cohort. The most common treatment-related adverse events (AE) were abdominal pain (36%), diarrhea (19%), nausea (16%) and fatigue (10%). There was only 1 treatment-related Grade 3 AE of abdominal pain. At 12 weeks, the PSA response was 91% (tx-naïve) and 60% (post-AA), respectively.

Conclusion

In men with CRPC, ARN-509 is safe and well tolerated with promising preliminary activity in metastatic, chemo-naïve patients both before and after treatment with abiraterone.

Disclosure

E. Chow-Maneval: Dr. Chow Maneval is an employee of Aragon and holds stock in the company.

All other authors have declared no conflicts of interest.