ZIOPHARM Oncology, Inc. (Nasdaq: ZIOP) announced today positive top line interim data from the multicenter randomized Phase II trial of palifosfamide (ZymafosTM, ZIO-201) treating patients with unresectable or metastatic soft tissue sarcoma. The analysis evaluated 62 patients treated as of the end of September, with 58 being analyzed. As a result of reaching a key efficacy milestone and following safety and efficacy data review by the Data Committee, sarcoma experts, and the Company’s Medical Advisory Board, the decision was reached formally to stop enrollment yesterday in the trial. The Company will report the interim data in full at the upcoming Connective Tissue Oncology Society (CTOS) Annual Meeting on November 5th and plans to initiate a registration trial following regulatory review of the palifosfamide program to date.
The Randomized Phase II trial treats patients with unresectable or metastatic soft tissue sarcoma in the front- and second-line setting. Patients are randomized either to doxorubicin (the current only FDA approved agent in sarcoma) or to palifosfamide in combination with doxorubicin. A total of 58 patients have been evaluated for PFS (progression-free survival) with 19 documented PFS events (doxorubicin alone = 13 events; palifosfamide + doxorubicin = 6 events) based on a three month median follow-up time. With this analysis based on all randomized and eligible patients, the hazard ratio is 0.67 favoring palifosfamide + doxorubicin (two-sided Wilcoxon-Gehan p-value = 0.042); the pre-defined milestone was to reach one-sided>
The interim safety data indicate that the addition of palifosfamide does not add to the toxicity of single agent doxorubicin. The most frequently reported side effects in both arms of the study include neutropenia and fatigue, hypokalemia, nausea, anemia, leucopenia, and alopecia. Palifosfamide is usually easily administered as an out-patient treatment, and generally well-tolerated.
“The hypothesis of the randomized Phase II trial design for this very difficult to treat cancer population has been validated and the interim results are promising and supportive of a pivotal trial,” said Robert Maki, MD, PhD, co-leader of the adult sarcoma program at Memorial Sloan-Kettering Cancer Center, and current President of CTOS (Connective Tissue Oncology Society), a multidisciplinary sarcoma specialty group.
“This will hopefully continue to progress forward step by step and result in a new treatment option for patients with a high unmet need” said Murray Brennan, MD, Chairman Emeritus of Surgery at Memorial Sloan-Kettering Cancer Center, renowned sarcoma expert and Lead Director at ZIOPHARM.
More detailed data will be reported at CTOS. Subsequently, the Company will be formalizing a final registration trial plan for review by the appropriate regulatory authorities.