GTx, Inc. (Nasdaq: GTXI) today announced the achievement of the Stage 1 milestone for the 18 mg cohort of its Phase 2 clinical trial of enobosarm (GTx-024) to treat women with advanced, estrogen receptor positive (ER+), androgen receptor positive (AR+) breast cancer. A pre-defined number of patients demonstrated clinical benefit per protocol to allow the clinical trial to advance to the second and final stage of the trial (Stage 2) for the 18 mg cohort. In September, GTx announced that it had achieved the Stage 1 milestone for the 9 mg cohort of the clinical trial, and that it was enrolling patients in the second and final stage for that dose group. The Company anticipates reporting Stage 1 data from the 9 mg dose group in December 2016. "The demonstration of clinical benefit among a pre-defined number of evaluable patients in Stage 1 of both the 9 mg and 18 mg cohorts of our ER+/AR+ breast cancer study continues to validate our belief that enobosarm may provide a new hormonal approach to the treatment of this advanced breast cancer," said Robert J. Wills, Ph.D., Executive Chairman of GTx. "We look forward to reporting top-line data from Stage 1 of the 9 mg cohort in the study later this year." About the Phase 2 Clinical Trial in ER+/AR+ Breast Cancer The open-label, multi-center, multinational Phase 2 clinical trial (NCT02463032) will assess the efficacy and safety of orally administered enobosarm in up to 88 evaluable patients with metastatic or locally advanced, ER+/AR+ breast cancer. Patients will receive orally-administered enobosarm (9 mg or 18 mg) daily for up to 24 months. The two dose cohorts in the trial will be treated independently for the purpose of assessing efficacy. The first stage of evaluation will be assessed among the first 18 evaluable patients for each cohort. If at least 3 of 18 patients achieve clinical benefit at week 24, then the trial will proceed to the second stage of enrollment for that cohort to assess clinical benefit in a total of 44 evaluable patients per arm. Clinical benefit is defined as a complete response, partial response, or stable disease, as measured by Response Evaluation Criteria in Solid Tumors (RECIST) at 24 weeks. The lead investigator for the trial is Dr. Beth Overmoyer from the Dana Farber Cancer Institute and the Harvard Medical School.