Aragon Pharmaceuticals Announces Clinical Results from Ongoing Phase II Trial Confirming Robust Anti-Tumor Activity and Tolerability of ARN-509 in Three Different Patient Populations of Castration Resistant Prostate Cancer

SAN DIEGO, Oct. 1, 2012 /PRNewswire/ -- Aragon Pharmaceuticals Inc., a leader in developing drugs for hormone driven cancers, announced new data from an ongoing, open-label, multicenter Phase II study of ARN-509, the company's 2nd generation androgen receptor antagonist, demonstrating promising results of ARN-509 in three separate patient populations with castration resistant prostate cancer (CRPC).  Data were presented at the European Society for Medical Oncology 2012 Annual Meeting in Vienna, Austria.

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An interim analysis of 93 patients enrolled across three distinct patient populations, including high risk non-metastatic CRPC, treatment-naive metastatic CRPC and metastatic CRPC that progressed after prior treatment with abiraterone acetate (Zytiga®) showed that treatment with ARN-509 was very well tolerated and resulted in robust and durable PSA responses, as well as evidence of objective responses.

These data add to the growing body of clinical experience with ARN-509, where a total of 127 patients have been treated to date, with the longest patient still on study after 2 years of treatment.

"Based on the observed activity and favorable safety profile, ARN-509 is a promising therapy to address important unmet medical needs for men with prostate cancer," said Matthew R. Smith, M.D., Ph.D., Professor of Medicine Harvard Medical School, Program Director, Genitourinary Oncology at Massachusetts General Hospital Cancer Center.

Metastatic CRPC Patients

A total of 25 patients with chemotherapy and abiraterone-naive metastatic CRPC who had progressed on standard androgen deprivation therapy (Treatment-Naive [TN]) and 21 patients who progressed after treatment with abiraterone-acetate (Post-Abi [PA]) were treated with the recommended Phase II dose of ARN-509 at 240 mg per day.  The primary objective was to assess antitumor activity and PSA kinetics as defined by the Prostate Cancer Clinical Trials Working Group (PCWG2) criteria.  Preliminary results demonstrated 12-week PSA declines of > 50% or more from baseline in 88% and 29% of the TN and PA cohorts, respectively.  The median time to PSA progression has not been reached for the TN cohort, and was 16 weeks in the PA cohort.  In addition, the objective response rate (by RECIST) was 63% in the TN patients presenting with measurable disease at baseline, further confirming the antitumor activity of ARN-509.  The drug was well tolerated in this patient population.

"These results showed that ARN-509 is safe and active in chemotherapy-naive metastatic CRPC, particularly for treatment-naive patients," said Dana Rathkopf, M.D., Assistant Attending Physician, Genitourinary Oncology Service at Memorial Sloan-Kettering Cancer Center and Principal Investigator on the study.

Non-Metastatic CRPC Patients

A total of 47 patients with non-metastatic CRPC were treated with ARN-509.  At 12 weeks of treatment, 91% of the patients had a > 50% decline in PSA as compared to baseline.  At 24 weeks, the percentage of patients who had > 50% decline in PSA remained at 91% and the percentage of patients who had > 90% decline in PSA was 55%, confirming the durability of response to ARN-509.  The median time to PSA progression has not been reached. The safety profile throughout all of the three distinct cohorts, confirmed the excellent tolerability seen during Phase I, where the most common adverse events reported were primarily Grades 1 and 2 fatigue and GI toxicities.

"We are pleased with the robust PSA response rates and continued excellent tolerability of the drug across all three patient cohorts," said Richard A. Heyman, Ph.D., President and CEO of Aragon Pharmaceuticals.  "We believe the totality of these data, as well as our earlier Phase I data, provide multiple options for development of ARN-509 both as monotherapy and as combination therapy for advanced prostate cancer."

About Aragon Pharmaceuticals

Aragon Pharmaceuticals is focused on the development of 2nd generation anti-hormonal agents for hormone-driven cancers.  The company's portfolio of small molecule therapeutics is based upon pioneering research identifying key molecular events that lead to drug resistance to traditional anti-hormonal therapies.  This work has broad implications for the development of breakthrough medicines for prostate cancer and other hormone-dependent cancers such as breast, ovarian and endometrial cancer.  Aragon Pharmaceutical's most advanced compound, ARN-509, is an androgen receptor antagonist that is currently being evaluated in a Phase 2 trial in patients with castration-resistant prostate cancer.  In addition, Aragon Pharmaceuticals has a selective estrogen receptor degrader (SERD) for hormone-sensitive and hormone-resistant estrogen receptor positive breast cancer targeted to begin clinical trials in 2013.  Aragon is a private company founded in 2009 and headquartered in San Diego, California.  For more information, visit www.aragonpharm.com.

SOURCE Aragon Pharmaceuticals