Using Ovarian Tumor Type to Predict Rx Benefit

Bevacizumab may improve survival of patients with proliferative and mesenchymal ovarian cancers

(RxWiki News) Customizing treatments based on a patient’s genetics has led to more effective cancer treatments. Now, researchers have reported using ovarian cancer tumor types to predict how much one medication might benefit patients.

Bevacizumab is an antibody that inhibits the formation of blood vessels. It is used as a medication in some cancer treatments to stop the flow of blood to tumors, helping to stop their growth.

Previous studies of the antibody in women with cancer of the ovaries has shown that it can increase the time before the cancer recurs (comes back).

Ovarian cancer can involve many types of cells in the ovaries. One team of researchers felt that bevacizumab might be working best on certain types of ovarian cancers tumors.

Their newly-released research showed that bevacizumab significantly increased the time before cancer got worse in women with one type of ovarian cancer.

"Ask your oncologist about personalized cancer treatments."

Sean C. Dowdy, MD, gynecologic oncologist at the Mayo Clinic in Rochester, Minnesota, was the senior author of this research.

The research team used ovarian tissue obtained during biopsies from 380 patients with ovarian cancer. They looked at the molecular make-up of the ovarian cancer tissue in the biopsies.

The researchers examined different molecules in the tissues and used the results to classify the tumors into four sub-groups or types. The tumor subtypes were called either proliferative, mesenchymal, immunoreactive or differentiated.

The researchers compared the tumor subtypes with the women’s response to treatment. Specifically, they were looking for the length of time before the cancer got worse in women treated with or without bevacizumab.

Of the 380 patients, about one-third had the immunoreactive subtype, about a quarter had the proliferative or differentiated subtype, and a fifth of the women had the mesenchymal subtype of ovarian cancer.

Bevacizumab treatment in the women with the mesenchymal subtype of ovarian cancer increased the time before cancer progressed by 9.5 months compared to those not treated with bevacizumab.

Compared to not being treated with the medication, bevacizumab treatment of patients with the differentiated subtype of ovarian cancer led to a 5.8-month increase in the time to cancer progression.

Women with the proliferative or immunoreactive subtypes of ovarian cancer showed just over a 3 month increase in the time before the cancer progressed compared to those not treated with bevacizumab.

The abstract authors concluded that, "Patients with mesenchymal subtype ovarian cancer may be most likely to obtain sustained benefit from treatment with bevacizumab."

Dr. Dowdy said that bevacizumab is extremely expensive and can have serious side effects, so using it for everyone with an ovarian cancer diagnosis is not practical.

He continued, “But if we could identify those patients who will see a 10-month improvement in progression-free survival, it would be worth treating them with the drug. On the other hand, avoiding the use of bevacizumab in patients unlikely to respond will allow us to reduce unnecessary toxicity and prescribe other, potentially more effective drugs for that particular patient.”

A scientific abstract of this study was presented June 1 at the annual meeting of the American Society of Clinical Oncology in Chicago, Illinois. The research has yet to be published in a peer-reviewed journal.

Funding for the research was provided by the Mayo Clinic SPORE in ovarian cancer and the Mayo Clinic Cancer Center.

One of the study's author, Jian-Bing Fan, disclosed employment at Illumina, the company who provided tumor classification technology for the study.

Review Date: 
June 3, 2014