EC17 for Intraoperative Imaging in Occult Ovarian Cancer

The overall prevalence of Ovarian Cancer in the United States according to the US SEER Registry is 182,710 women. Ovarian cancer also has the highest mortality rate of the gynecological cancers. The overall five-year survival rate is 45% and for Stages III and IV it is only 20-25%. The majority of these are aged 50 years or older, but a few girls less than 10 years of age have been diagnosed with ovarian cancer. This risk increases with age and decreases with numbers of pregnancies.

The prognosis for many carcinomas is dependent on the extent of surgical resection. At present, the ability to perform a complete resection with negative margins is limited by the investigator's ability to palpate and visualize the tumor and its borders. In many cases, a more radical resection than necessary is performed in order to provide assurance that negative margins are achieved. This approach may also increase complication rates, as well as short- and long-term morbidity. It is desirable to improve visualization of primary tumors and occult metastases in real time, during surgery. The use of fluorescent probes that recognize cancer-specific antigens, in conjunction with a clinical imaging system, is under investigation.

Ovarian cancer is a prototypic disease for this type of clinical imaging system called intra-operative imaging. Except in Stage IV, the tumors are confined to the pelvis or abdomen and typically involve extensions or implants onto pelvic or abdominal organs or membranes. Tumor debulking surgery is common early in the disease process as many of the tumors can be identified by appearance or feel in the skilled surgeon's hands. The major problems are that tumors can be diffuse and numerous, of various sizes, and often not readily visible in the surgical field.

Over 90-95% of serous ovarian cancers express folate receptor (FR)-alpha, making this receptor an ideal target for marking most ovarian cancers. Folate is the prototypic agonist at the FR-alpha with potential uses for imaging and targeted therapeutic strategies.Chemotherapy does not affect FR-alpha expression in ovarian cancer specimens examined by immunohistochemistry, so prior treatment is unlikely to affect utility of FR-alpha agonists as imaging or therapeutic agents.