The study reviewed here suggests that the experimental medicine Efaproxyn (chemical name: efaproxiral) doesn't improve the benefits of radiation therapy to the brain to treat breast cancer that has spread there.
The results were presented at the 2008 American Society for Therapeutic Radiology and Oncology (ASTRO) meeting.
Metastatic breast cancer is cancer that has spread to other body organs, such as the bones, liver, or brain. Metastatic breast cancer can be the first diagnosis or it can be diagnosed after the cancer comes back (recurrence). Many women live for years with metastatic cancer that's controlled. Living with metastatic breast cancer is like living with a chronic disease. It can be in remission, it can be active, or it can be inactive. Living with metastatic breast cancer can mean trying one treatment after another, ideally with breaks in between treatments when you feel good. The goal of treatment is to help you feel as good as possible and live a longer life.
Radiation therapy to the brain is one way to shrink breast cancer that has spread there. Radiation therapy to the brain often is given with other treatments such as chemotherapy, hormonal therapy, or targeted therapy.
Efaproxyn is a radiation sensitizer. When given with radiation therapy, Efaproxyn is expected to make the radiation more effective at killing cancer cells. Efaproxyn increases the amount of oxygen in cancer cells. Sometimes cancer cells don't have high amounts of oxygen. It's thought that giving cancer cells more oxygen will make them more susceptible to radiation.
In this study, 365 women were treated with radiation therapy to the brain for two or more areas of metastatic breast cancer. About half of the women got Efaproxyn and the rest didn't. The response to the radiation therapy was the same for both groups of women. The Efaproxyn didn't make a difference in how the cancer responded to the radiation therapy.
A previous study suggested that Efaproxyn improved the response to radiation therapy in people being treated for metastatic cancers, but another study did not show any benefit. So the researchers thought it needed more testing.
Improvements in treatments for advanced-stage breast cancer have not kept pace with improvements in treatments for early-stage breast cancer. Doctors continue to work very hard to find new and better ways to treat advanced-stage breast cancer, including metastatic breast cancer. It can be disappointing to find out that a promising treatment doesn't work. But these results add to our understanding of breast cancer and help focus research on other treatments.
Visit the Recurrent and Metastatic Breast Cancer section to learn more about metastatic breast cancer and its treatments.
BOSTON, Sept. 24 (MedPage Today) -- An investigational radiation sensitizer, efaproxiral (Efaproxyn), had no significant benefit for women whose breast cancers had spread to the brain, a researcher said here.
The finding contrasts with an earlier study that had seemed to show a benefit for women who got efaproxiral combined with whole-brain radiation, according to John Suh, M.D., of the Cleveland Clinic.
"Our hope was we'd improve survival by 30% to 40%," Dr. Suh said at the American Society for Therapeutic Radiology and Oncology meeting.
Instead, the phase III open-label trial showed no difference in overall survival, response rate, performance status, or neurological signs and symptoms, Dr. Suh said.
The drug is an allosteric modifier of hemoglobin that causes a shift of the hemoglobin oxygen dissociation curve to the right, so that oxygen is more easily released from hemoglobin into tissues.
The theory is that radiation therapy is sometimes ineffective because the tumor is hypoxic, so that more oxygen in the tumor tissue should improve radiation sensitivity.
But a phase III trial, reported in 2005, showed no overall survival benefit for the drug combined with whole brain radiation for patients with all types of tumors that had spread to the brain, Dr. Suh said.
However, a planned sub-group analysis of women with brain metastases from breast cancer showed a significant improvement (at P=0.0061) in mean survival time, from 4.57 months to 8.67 months.
There were also improvements in response rates and quality of life, leading the investigators to begin a confirmatory phase III trial, dubbed ENRICH (RT-016), that included only women with metastatic breast cancer.
The study included 365 women, most of whom had two or more brain lesions. They were treated with three Gray of whole brain radiation daily for 10 days, with or without efaproxiral delivered by a central venous access device. All the patients got supplemental oxygen.
Analysis found:
Dr. Suh noted that survival in the control arm was longer than had been expected.
Researchers have been hunting for ways to improve radiation therapy, and drugs such as efaproxiral seemed promising, according to Ramesh Rengan, M.D., Ph.D., of the University of Pennsylvania, in Philadelphia, who was a discussant for the presentation.
But "although this drug may increase oxygen delivery, it has not had an impact on the efficacy of radiation," Dr. Rengan said.
The primary endpoint of this study was survival, but he said a more important endpoint, from the point of view of measuring the effect of the drug, might be tumor response.
But even there, he said, there was only a "slight difference" that did not reach statistical significance.
The study was sponsored by Allos Therapeutics, Inc., which is developing the drug.
Dr. Suh reported financial links with Schering-Plough.
Dr. Rengan stated he had no disclosures.
Primary source: International Journal of Radiation Oncology - Biology - Physics Source reference: Suh JH, et al "Results of the Phase III ENRICH (RT-016) Study of Efaproxiral Administered Concurrent with Whole Brain Radiation Therapy (WBRT) in Women with Brain Metastases from Breast Cancer" Int J Radiat Oncol Biol Phys 2008; 72(1 Suppl): Abstract 110.
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