Is anyone on "this" study or has further information on the below intermittent treatment?
THanks,
Nguyen
"Overcoming resistance in receptor-positive disease
Hormone receptor-positive breast cancer accounts for approximately 60 percent of all breast tumors. The hallmark of these tumors is a high number of estrogen receptors (ER) and/or progesterone receptors (PgR), which stimulate cell growth when bound by these hormones. Their hormone dependency renders these tumors vulnerable to targeted endocrine therapies including tamoxifen and aromatase inhibitors that deprive tumors of estrogen. But although aromatase inhibition (AI) has demonstrated “a modest disease-free survival benefit” compared with tamoxifen, explains breast cancer specialist Paula Ryan, MD, PhD (MGH), resistance remains a critical problem. Thus she and co-investigator Paul Goss, PhD (MGH) — an international expert on endocrine therapy and leader of the Breast Cancer Program — have embarked on several novel studies to thwart the tumor’s development of resistance and improve patients’ progression-free survival.
In one study, investigators are attempting to suspend or delay resistance by administering the aromatase inhibitor letrozole intermittently. This on-off strategy is premised on the observation that as tumor cells become chronically estrogen-deprived, they develop hypersensitivity to the hormone. Just how this happens is unclear, notes Ryan. “When all estrogen-sensitive cells in the tumor are eliminated, that may leave only drug-resistant clones,” she hypothesizes. “If we interrupt AI, we hope to retain some intratumoral heterogeneity,” which may control the growth of drug-resistant cells.
A unique aspect of this study is the use of CA 15-3 as a tumor marker to help determine, in combination with scans and monthly clinical evaluation, when to make changes in therapy. “Once we’ve seen that patients have responded to AI, we stop their therapy and watch the marker,” explains Ryan. “If it goes up 25 percent, we put them back on the drug.” This process is repeated in a cyclical fashion, using the tumor marker to dictate when to halt or reintroduce letrozole.
http://www.dfhcc.harvard.edu/news/ne...icle/1973/334/
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Linear Mode
