Experimental Drug Used To Treat Recurrent Ovarian Cancer Shows Promising Results

The data were presented by David O'Malley, M.D., instructor, Department of Obstetrics, Gynecology & Reproductive Sciences, at the 35th Annual Meeting of the Society of Gynecologic Oncologists in San Diego, California on February 8. The researchers found no toxicity, 25 percent response and synergy with chemotherapy. The main purpose of the study was to determine the dose of phenoxodiol to be used in combination with other anti-cancer drugs.

While phenoxodiol has the ability to stop ovarian cancer growth in animals in its own right, Yale researchers and the drug's developer, Marshall Edwards, Inc., are developing the drug in late-stage ovarian cancer as a chemo-sensitizer, restoring the sensitivity of the cancer cells to standard chemotherapeutic drugs.

"Patients received phenoxodiol twice a week, which is how we believe it will be used in combinational therapy," said principal investigator Thomas Rutherford, M.D., associate professor of gynecology, Department of Obstetrics, Gynecology & Reproductive Sciences. "We did expect to see a major anti-tumor effect when used at this dose, with an apparent 25 percent stability rate in unresponsive cancers. These results gave us confidence in the potential use of phenoxodiol for the treatment of ovarian cancer. We are highly encouraged by the outcome."

The data reflected outcomes from the first 20 of 40 patients enrolled in the study with late-stage ovarian cancer that had become unresponsive to standard chemotherapy. Of the 20 patients who started the course of treatment, 13 were able to finish a three-month program without disease progression. Five of these patients were evaluated to have disease stabilization; all these patients later progressed.

In a follow up of the study, eight of nine patients who were treated with paclitaxel-standard chemotherapy-following completion of the phenoxodiol trial showed a positive serologic response to paclitaxel therapy. Four of these patients had previously been defined as paclitaxel resistant.

"This is a preliminary observation only, but one that we find highly encouraging because it confirms in humans what we saw in the laboratory -- that phenoxodiol is a powerful chemo-sensitizer," said Gil Mor, M.D., PhD, associate professor and a co-investigator in the study.