Letrozole (Femara) early and late responses to treatment
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Miller WR
PROVIDER: S-ECPF-GEOD-20181 | biostudies-other | 2012 Feb
REPOSITORIES: biostudies-other
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Project description:In the present investigation, we have exploited the opportunity provided by neoadjuvant treatment of a group of postmenopausal women with large operable or locally advanced breast cancer (in which therapy is given with the primary tumour remaining within the breast) to take sequential biopsies of the same cancers before and after 10-14 days or 90 days treatment with letrozole. RNA extracted from the biopsies has been subjected to Affymetrix microarray analysis and the data from paired biopsies interrogated to discover genes whose expression is most influenced by oestrogen deprivation. Keywords: Timecourse between subjects Biopsies were taken from the same subjects at three timepoints: pretreatment, after 10-14 days Letrozol (2.5 mg/day, oral), and after 90 days Letrozol (2.5 mg/day, oral).
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Project description:Data suggest that estrogen-containing hormone therapy is associated with beneficial effects with regard to cardiovascular disease when the therapy is initiated temporally close to menopause but not when it is initiated later. However, the hypothesis that the cardiovascular effects of postmenopausal hormone therapy vary with the timing of therapy initiation (the hormone-timing hypothesis) has not been tested.A total of 643 healthy postmenopausal women were stratified according to time since menopause (<6 years [early postmenopause] or ?10 years [late postmenopause]) and were randomly assigned to receive either oral 17?-estradiol (1 mg per day, plus progesterone [45 mg] vaginal gel administered sequentially [i.e., once daily for 10 days of each 30-day cycle] for women with a uterus) or placebo (plus sequential placebo vaginal gel for women with a uterus). The primary outcome was the rate of change in carotid-artery intima-media thickness (CIMT), which was measured every 6 months. Secondary outcomes included an assessment of coronary atherosclerosis by cardiac computed tomography (CT), which was performed when participants completed the randomly assigned regimen.After a median of 5 years, the effect of estradiol, with or without progesterone, on CIMT progression differed between the early and late postmenopause strata (P=0.007 for the interaction). Among women who were less than 6 years past menopause at the time of randomization, the mean CIMT increased by 0.0078 mm per year in the placebo group versus 0.0044 mm per year in the estradiol group (P=0.008). Among women who were 10 or more years past menopause at the time of randomization, the rates of CIMT progression in the placebo and estradiol groups were similar (0.0088 and 0.0100 mm per year, respectively; P=0.29). CT measures of coronary-artery calcium, total stenosis, and plaque did not differ significantly between the placebo group and the estradiol group in either postmenopause stratum.Oral estradiol therapy was associated with less progression of subclinical atherosclerosis (measured as CIMT) than was placebo when therapy was initiated within 6 years after menopause but not when it was initiated 10 or more years after menopause. Estradiol had no significant effect on cardiac CT measures of atherosclerosis in either postmenopause stratum. (Funded by the National Institute on Aging, National Institutes of Health; ELITE ClinicalTrials.gov number, NCT00114517.).
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Project description:Tumorigenic breast cancer cells characterized by high CD44 and low or undetectable CD24 levels (CD44+/CD24-/low) may be resistant to conventional therapies and responsible for cancer relapse. We defined a âsignatureâ expression pattern of hundreds of genes associated with CD44+/CD24-/low, mammosphere-forming cells. In a panel of patient breast tumors, this tumorigenic gene signature was found exclusively manifested in tumors of the recently identified âclaudin-lowâ molecular profile subtype characterized by overexpression of many mesenchymal-associated genes, suggesting that these tumors have pre-existing higher levels of tumorigenic cells. Furthermore, when comparing the expression profiles of paired breast cancer core biopsies before versus after hormone therapy or chemotherapy, both the tumorigenic and âclaudin-lowâ signatures were more active in about half of tumors after treatment, indicative of a greater enrichment of tumorigenic cells as a result of treatments targeting the bulk tumor cells. Experiment Overall Design: Biopsies were taken from the same subjects both pretreatment and after 10-14 days Letrozol, 2.5 mg/day, oral.
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