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Targeting Resistance to Endocrine Therapy in Advanced Breast Cancer
Untitled Document
Name of the Trial
Phase III Randomized Study of Tamoxifen Citrate or Letrozole With Versus Without
Bevacizumab in Women With Hormone Receptor-Positive Stage IIIB-IV Breast Cancer
(CALGB-40503). See the protocol
abstract.
Principal Investigator
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Dr. Maura Dickler
Principal Investigator |
Dr. Maura Dickler, Cancer and Leukemia Group B
Why This Trial Is Important
The female hormone estrogen, which is an endocrine
hormone, can stimulate the growth many breast cancers. In addition, estrogen
can promote the growth of new blood vessels (angiogenesis) to tumors, which
helps the tumors get the oxygen and nutrients they need for continued growth.
Hormonal therapies, such as letrozole
and tamoxifen,
can help delay the progression of breast cancers that grow in response to estrogen.
Letrozole, an aromatase inhibitor, interferes with the body's ability to produce
estrogen, and tamoxifen, an antiestrogen, competes with estrogen for binding
to estrogen receptors. However, most patients with advanced breast cancer eventually
develop resistance to hormonal therapy and experience relapse.
Some preclinical research has suggested that a possible cause for this resistance
is the hormone-independent growth of blood vessels to tumors. Doctors want to
know if inhibiting this angiogenesis with an antibody
known as bevacizumab
can help delay the development of resistance to hormonal therapy. Bevacizumab
blocks the activity of vascular endothelial growth factor (VEGF), a protein
that is important for angiogenesis.
In this trial, women with advanced, hormone receptor-positive breast cancer
will be randomly assigned to receive hormonal therapy (with letrozole or tamoxifen)
and either bevacizumab or a
placebo. The decision of whether to take letrozole
or tamoxifen will be made by patients and their doctors. Researchers want to
determine whether the addition of bevacizumab will slow disease progression
in women receiving hormonal therapy.
"This trial is intended to provide definitive proof of whether anti-VEGF
therapy adds to the benefit of endocrine therapy in advanced breast cancer,"
said Dr. Dickler.
"One important aspect of this trial is that women do not have to have
a measurable tumor to be included," she added. "Many women experience
recurrence in the form of non-measurable disease, such as bone metastases, pleural effusions, or lymph node metastases, and these women may be eligible for this
study."
The investigators plan to answer additional questions with the trial as well.
For example, women will be monitored to see if the addition of bevacizumab causes
more, or different, side effects than does letrozole or tamoxifen alone.
For More Information
See the lists of entry
criteria and trial
contact information or call the NCI's Cancer Information Service at 1-800-4-CANCER
(1-800-422-6237). The toll-free call is confidential.
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