OCRP 2012 Investigator Vignette

Title: Urinary Biomarkers for Ovarian Cancer

Investigators: Santo Nicosia, MD, MS and Patricia Kruk, PhD; University of South Florida

Kruk: Ovarian cancer is probably the most deadly gynecologic cancer. To date, probably one in maybe only 39 women are diagnosed with cancer of the ovary every year but it is the most lethal gynecological cancer. So about 12,000 women a year die from the disease

Nicosia: If the cancer is discovered in the early stage, so stage 1, the survival is excellent, probably 85%-90% or better. But if, as usual, it is discovered in the late stages, survival is less than 30%. So one of the reasons for such a dismal fact is that we do not have a good screening diagnostic marker for ovarian cancer.

Kruk: Up to date, there has only been a limited detection method that includes a blood test for CA125 levels which have limited detection ability, as well as pelvic examination and transvaginal ultrasound.

Nicosia: In the mid to late 90s, we began to ask the question can we identify a biomarker in epithelial ovarian cancer. And in collaboration with my brother who is at the University of Washington, Seattle, we began aspirating the fluid content of benign and malignant ovarian lesions, ovarian cysts, to look for the presence of factors which regulate the formation of new blood vessels; the process called angiogenesis. The most frequent ovarian cancer is what we call serous papillary carcinoma. It forms papillae, fibervascular structures which contain very prominent blood vessels. So we knew that the process of angiogenesis was very important for ovarian and other cancer, so we measure a number of factors, two of which regulate angiogenesis in a positive way; we call it angiogenic factors, VEGF and HGF, and two of them which in a yin yang fashion negatively regulates angiogenesis, supresses angiogenesis. And these are called endostatin and angiostatin. And angiostatin was the one which was the most consistently, significantly elevated in this fluid.

Angiostatin is a bi-product of a larger molecule which we call plasminogen, which circulates in the blood. And because of its smaller size, this substance can be filtered through the kidney and detected in the urine of patients.

So what we see now in the study, we see that when we look at angiostatin expression (levels) in the urine, angiostatin was very low/negligible level in pre- and post-menopausal women; was somewhat elevated, but not very much, in women with benign ovarian cysts; but was markedly elevated in women with ovarian cancer. Was more elevated in women with advanced ovarian cancer, late stages, but also in women with early so stage 1 of ovarian cancer-an important finding to be completely validated because survival of stage 1 is 85% to 90% over 5 years versus less 30% in advanced stage.

We look at a number of cancers that our series has expanded in the last year, and again we saw there was variation in ovarian cancer in women but there was elevation in almost all of them except 3 or 4 women. We saw there was an increased expression of angiostatin with each stage, but this increase was not significantly different. Angiostatin was basically at the lower threshold in women with benign ovarian lesions, except 3 or 4 of them. And we are trying to find out why that is the case.

When we follow patients after surgery, we also note this good correlation between angiostatin and status of the disease. So if you look here in the blue, the women where the tumor was removed successfully and never recurred, at least for the period we followed, angiostatin level decreased after surgery and remained very low. But in women where the disease were either chemo resistant or returned, came back, months after surgery, the angiostatin level went up again.

We compared also angiostatin with the gold standard biomarker today for ovarian cancers, CA125, and we noticed that there was fairly good correlation. But also we noticed that in the same case where CA125 was low, angiostatin was high and vice versa. So we think that angiostatin adds complementarity to CA125 and that makes a case for the possible, possible relevance of utilizing panels of markers versus utilizing one single marker.

What will we do next? We need verify how specific or not specific is the biomarker angiostatin for ovarian cancer. So we're looking at various cohorts of not only healthy in women with benign disorder, but also women with ovarian cancer in other types of cancers. And that's what we will be doing in the next 2 years.

Dr. Kruk is a co-investigator on the grant. We work together very well and she has a DoD grant to look at the expression of Bcl-2, an antipoptopic protein in urine and blood.

Kruk: Bcl-2 is normally a cellular protein that is involved in what we call programmed cell death. It controls whether a cell should undergo cell death when it has reached its end limit. It is not generally ever been found outside the cell, and so our studies are very novel in that for some odd reason the ovarian cancer cells show they shed this protein as well.

So far, our studies today indicate that urinary levels of Bcl-2 appear only elevated in women with ovarian cancer. It does not appear to be elevated in other forms of cancer. So this may be a rather specific biomarker for ovarian cancer. So we are currently collaborating with individuals at multiple institutions including the MD Anderson Cancer Center to validate how well urinary Bcl-2 stands up as a urinary biomarker to detect the disease.

Up until our studies, there had been no indication that there may be urinary proteins that could be used to detect ovarian cancer. The use of urinary proteins obviously provides a very easy economical testing for the disease and we could test at long distances.

Nicosia: So I think that urine provides a human specimen, which should be readily available, available for noninvasive approaches and should make also this test available not only to populations in larger cities but also in populations of women at risk in underserved areas in this country and abroad. So I think this shows the innovation and applicability of our current study.

Kruk: We've been 10 years struggling and almost feeling defeated. But one happy moment, one good piece of data will keep you sustained for a long time.