REOLYSIN shown to benefit some sarcoma patients

New data shows that some sarcoma patients are benefiting from treatment with REOLYSIN, developed from a harmless virus called the reovirus that most people are exposed to at some point in their lives.

Dr. Monica Mita of the Institute of Drug Development (IDD), the Cancer Therapy and Research Center at the University of Texas Health Science Center, (UTHSC), San Antonio, Texas, delivered her findings at both the Connective Tissue Oncology Society (CTOS) annual meeting in London, U.K. and the Chemotherapy Foundation Symposium XXVI in New York in November 2008. Her oral presentation discussed the interim results of a U.S. Phase II trial investigating intravenous REOLYSIN in patients with bone and soft tissue sarcomas metastatic to the lung.

"The standard treatment for this type of sarcoma is chemotherapy, but prognosis is poor since there is no cure," said Dr. Mita. "Patients with only a few months to live face poor quality of life because chemotherapy treatments are so harsh. The goal is to introduce less invasive approaches that help extend life and provide patients with a better quality of life."

REOLYSIN, being developed by Oncolytics Biotech Inc, a Calgary-based company, preferentially replicates in cancer cells with an activated RAS pathway. Approximately two thirds of all cancers have an activated RAS pathway, including most metastatic disease. The reovirus is a segmented double-stranded RNA virus that causes only mild illness in humans. Although the virus replicates robustly in cancer cells expressing Ras, a cancer signaling pathway, it spares normal cells. Viral replication within cancer cells causes them to burst open, releasing more virus to infect other cells.

To date, thirty-five patients have been enrolled in the study, and twenty-nine are evaluable. A fifth (six of twenty-nine) of the evaluable patients experienced stable disease (SD) for more than sixteen weeks, an important benchmark for marking drug activity in these hard-to-treat cancers. Dr. Mita and her team of investigators concluded that the study has met its established objectives, and that enrollment will continue to the full fifty-two patients.

One trial patient with synovial sarcoma (a rare form of cancer that usually occurs near to the joints of the arm or leg) has stable disease after seventeen cycles of treatment, and continues on trial. One patient with Ewing's sarcoma (a type of bone tumor) experienced stable disease after nine cycles of REOLYSIN and continues on trial. One patient with malignant fibrous histiocytoma experienced stable disease after seven cycles (with a tumor resection after achieving stable disease at cycle four). This patient also continues to be treated in the trial. Other patients with rare types of tumors such as leiomyosarcoma, chordoma and unspecified spindle cell sarcoma have experienced stable disease for more than sixteen weeks.

"A 21% response in a patient population where nothing works at all is a major advance," says Oncolytics Biotech's CEO Dr. Brad Thompson, "particularly as the only side effects to date have been relatively mild."

The virus is delivered through cycles of daily forty-minute infusions for a week at a time, with gaps of three weeks in between.