REDWOOD CITY, Calif., Feb. 16, 2011 (GLOBE NEWSWIRE) -- Threshold Pharmaceuticals, Inc. (Nasdaq:THLD) today announced that the Company reached agreement with the U.S. Food and Drug Administration (FDA) on a Special Protocol Assessment (SPA) for a Phase 3 randomized trial of TH-302 in patients with soft tissue sarcoma. This pivotal trial is expected to begin in the middle of 2011, and will enroll patients with metastatic or locally advanced unresectable soft tissue sarcoma who have not previously received chemotherapy outside the adjuvant or neoadjuvant setting. The trial is designed to evaluate the efficacy and safety of TH-302 in combination with doxorubicin, compared to doxorubicin alone. "With this SPA, we have reached agreement with the FDA on the key features of our Phase 3 trial design that will be necessary to support the registration of TH-302," said Stewart Kroll, Threshold's Vice President, Biostatistics and Clinical Operations. "The proposed trial is designed to confirm the encouraging results that we have previously reported in our ongoing Phase 1/2 trial of soft tissue sarcoma patients treated with TH-302 in combination with doxorubicin." TH-302 Clinical Development Rationale and Strategy TH-302 has been investigated in over 400 patients with cancer as part of five clinical trials. The TH-302 clinical development program includes an ongoing Phase 1/2 trial in patients with soft tissue sarcoma. As presented at the Connective Tissue Oncology Society meeting in November 2010, fifty-four patients had at least one evaluable post-treatment tumor assessment and 18 of 54 (33%) had a partial response. The median progression free survival was 6.4 months (95% confidence interval: 5.6 to 6.9 months). These data formed the basis for the proposed Phase 3 study of TH-302 and doxorubicin compared to doxorubicin, as covered by the SPA. In addition, Threshold is pursuing additional clinical trials in patients with solid tumors as well as hematologic malignancies. TH-302 is currently being evaluated in a Phase 2 randomized, controlled combination trial in patients with metastatic or locally advanced pancreatic cancer as well as a Phase 1 open label, monotherapy trial in patients with advanced leukemias.