Gauging Ziopharm's Chances for Positive Sarcoma Drug Trial Results

NEW YORK (TheStreet) -- Biotech investors love the thrill and drama surrounding the release of phase III study results. Ziopharm Oncology (ZIOP) is about to provide just that with the release of top-line results for its PICASSO-3 study in the last week in March.

Ziopharm is developing palifosfamide for the treatment of advanced soft tissue sarcomas (STS), a rare form of cancer affecting approximately 10,000 people in the U.S. annually. Palifosfamide is an active form of an existing chemotherapy drug called ifosfamide frequently used in the treatment of STS. Unfortunately, ifosfamide has serious side effects when used at high doses or when combined with other forms of chemotherapy such as doxorubicin, a drug considered standard of care. Palifosfamide appears to lack such toxicities and can be given safely in combination with other chemotherapies without incremental side effects, thus making it an attractive agent in the treatment of STS.

In the majority of cases, STS is not cured and eventually spreads to other organs or parts of the body. The prognosis for patients with metastatic STS is very poor, with expected survival typically about one year. New, more potent treatments are needed that will help control the disease and improve survival outcomes for these patients.

Prior to launching the current palifosfamide PICASSO-3 study, Ziopharm conducted a phase II study of palifosfamide in STS dubbed PICASSO. This was a randomized, multi-center, open-label study of patients with unresectable or metastatic STS randomized to receive palifosfamide plus doxorubicin or doxorubicin alone. The two arms of the study were well matched for age and tumor type. The primary end point was progression-free survival (PFS) and was highly positive: Median PFS was 7.8 months in the palifosfamide-doxorubicin arm vs. 4.4 months for doxorubicin alone. The additional of palifosfamide to doxorubicin reduced the risk of tumor progression by 57% compared to doxorubicin alone. The partial response rate for the palifosfamide-doxorubicin was 23% vs. 9% for doxorubicin. There were no major differences in safety between the two arms indicating that the combination of palifosfamide and doxorubicin was safe.

Based on the positive data generated in the phase II PICASSO study, many Ziopharm investors are optimistic that equally positive results will be announced soon from the PICASSO-3 phase III study. Like PICASSO, the PICASSO-3 study compares the combination of palifosfamide plus doxorubicin against doxorubicin alone, with PFS as the primary endpoint. Ziopharm only has to replicate the results in PICASSO for the PICASSO-3 study to be successful.

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