Palifosfamide Trial Reaches Target for PFS Events

Jonathan Lewis, MD, PhD

The target number of progression-free survival (PFS) events was reached in a phase III trial comparing the investigational compound palifosfamide plus doxorubicin with doxorubicin plus a placebo for patients with first-line metastatic soft tissue sarcoma, meaning that data from the trial can now be analyzed by independent review. The findings were announced by Ziopharm Oncology, Inc., the drug’s manufacturer.

Palifosfamide is an alkylating agent that binds to the DNA of cancer cells, interfering with the function of those cells and halting tumor growth in the process. Previous research has shown that the drug may be a promising treatment for cancers with increased levels of aldehyde dehydrogenase (ALDH), an enzyme associated with resistance to treatment and poor clinical outcomes.

Soft tissue sarcoma is a relatively rare type of tumor that forms in the fat, muscles, nerves, joints, blood vessels, and deep skin tissues. According to the National Cancer Institute, approximately 11,280 patients were diagnosed with soft tissue sarcoma in the United States in 2012, and approximately 3900 patients died from the disease.

The phase III PICASSO 3 trial is an international, randomized, double-blind, placebo-controlled study taking place across 162 research locations across the world. Ziopharm did not disclose any data from the trial in its announcement, but the company said it will announce topline results from the trial during the last week of March 2013.

“Reaching the target number of progression events for PICASSO 3 positions us one step closer to understanding palifosfamide's full potential for this significant unmet medical need,” said Jonathan Lewis, MD, PhD, Chief Executive Officer of Ziopharm, in a statement. “With a positive study outcome, palifosfamide has the potential to become the first new treatment option in nearly 30 years for patients with first-line metastatic soft tissue sarcoma.”

The PICASSO 3 trial was launched after positive results were seen in a phase II trial, the results of which were presented at the American Society of Clinical Oncology (ASCO) meeting in 2010. That study found that the combination of palifosfamide and doxorubicin yielded a median PFS of 7.8 months in patients with metastatic and unresectable first- and second-line soft tissue sarcoma, compared with 4.4 months in the patients who received doxorubicin alone. The study did not find any significant difference in toxicities between the two arms

Verschraegen CF, Chawla SP, Mita MM, et al. A phase II, randomized, controlled trial of palifosofamide plus doxorubicin versus doxorubicin in patients with soft tissue sarcoma (PICASSO). J Clin Oncol. 2010;28:15s(suppl; abstr 10004).