Tokai Pharmaceuticals' galeterone well-tolerated in patients with advanced prostate cancer

(Press-News.org) CAMBRIDGE, Mass. and CHICAGO, Ill. -- Tokai Pharmaceuticals, Inc., a biopharmaceutical company focused on developing new treatments for prostate cancer, today announced that its lead candidate galeterone (TOK-001) was well-tolerated with minimal side effects and demonstrated efficacy in patients with castration-resistant prostate cancer (CRPC) in a Phase 1 study. The data will be presented in an oral presentation titled, "ARMOR1: Safety of galeterone (TOK-001) in a Phase 1 clinical trial in chemotherapy naïve patients with castration-resistant prostate cancer (CRPC)," abstract number CT-07, on Tuesday, April 3, 2012 at 3:05 p.m. (CDT) at the American Association for Cancer Research (AACR) Annual Meeting 2012 in Chicago.

CRPC is an advanced, difficult-to-treat form of prostate cancer that occurs when the disease progresses despite the use of anti-hormonal therapies. Galeterone is a small molecule, oral drug for the treatment of CRPC that disrupts the growth and survival of prostate cancer cells via a novel and proprietary triple mechanism of action.

"Because currently available therapeutic options to treat castration-resistant prostate cancer are limited, often poorly-tolerated and may fail because of resistance, patients are in urgent need of new safe and effective treatments," said Mary-Ellen Taplin, M.D., associate professor of medicine, director of genitourinary clinical research, Dana-Farber Cancer Institute, Harvard Medical School and co-lead researcher in the study. "These Phase 1 galeterone data, demonstrating minimal toxicities, improved PSA response and a reduction in tumor size, are exciting for those of us in the medical community treating this life-threatening cancer. I look forward to following the further development of galeterone as a promising approach in the treatment of prostate cancer."

The ARMOR1 study was led by co-principal investigators Dr. Taplin and Bruce Montgomery, M.D., associate professor of medical oncology at the University of Washington School of Medicine, and their colleagues at leading prostate cancer research centers in the United States. The Phase 1 proof-of-concept clinical trial, part of the ARMOR (Androgen Receptor Modulation Optimized for Response) clinical development program for the evaluation of galeterone, enrolled 49 patients and was a dose-finding study to evaluate escalating dose levels of galeterone. The study also evaluated safety and reduction in prostate-specific antigen (PSA) levels from baseline levels measured at first visit. Patients who responded to therapy had the option to continue treatment with galeterone in an extension arm of the trial.

Most side effects were minor and included fatigue, nausea and diarrhea. Early efficacy tests demonstrated that 49 percent of patients had prostate-specific antigen (PSA) reductions of 30 percent or more; 11 of these patients had reductions of 50 percent or more. In addition, CT scans revealed a significant reduction in tumor size for some patients.

"We are pleased with the results of our Phase 1 proof-of-concept study, which demonstrated galeterone tolerability and efficacy in a difficult-to-treat, resistant prostate cancer patient population," said Martin D. Williams, president and chief executive officer, Tokai Pharmaceuticals. "Galeterone is the only prostate cancer therapy in development that combines three distinct mechanisms of action in one compound for a unique multi-target approach. The reductions in PSA levels seen in nearly half of all patients evaluated in our Phase 1 study are meaningful in a dose-escalation study and supportive of our Phase 2 clinical trial set to initiate later this year."

In the Phase 1 study, researchers observed transient, non-serious elevated liver function tests in 15 patients, most of whom were asymptomatic. Eleven of these patients stopped galeterone treatment, and of those, six of seven patients were rechallenged and successfully returned to treatment with no significant recurrence in liver function test elevations.

A Phase 2 study evaluating long-term safety and efficacy of galeterone in CRPC patients is planned for the second half of 2012.

### About Galeterone (TOK-001) Galeterone is a small molecule, oral drug for the treatment of prostate cancer that disrupts the growth and survival of cancer cells via a novel and proprietary triple mechanism of action. In preclinical studies, galeterone acts as an androgen receptor antagonist, as a CYP17 lyase inhibitor and decreases androgen receptor levels in prostate tumors – the only drug in development that has been shown to exhibit this property. In galeterone, these three distinct mechanisms of action are combined in one therapy.

About Tokai Pharmaceuticals Tokai Pharmaceuticals is a U.S. biopharmaceutical company focused on developing new treatments for prostate cancer. The company's lead drug candidate, galeterone (TOK-001), is the first investigational new drug that can decrease overall androgen receptor levels in prostate tumors and in which three distinct mechanisms of action are combined in one oncotherapeutic. Privately held Tokai is based in Cambridge, Massachusetts and is backed by Apple Tree Partners and Novartis Venture Fund. For more information on the company and galeterone, please visit www.tokaipharma.com.