[4061] The SABRE (Study of Anastrozole with the Bisphosphonate RisedronatE) study: the effects of risedronate on BMD and bone metabolism in postmenopausal women using anastrozole as adjuvant therapy for hormone receptor-positive early breast cancer – first results.

Van Poznak C, Hannon RA, Clack G, Campone M, Mackey JR, Apffelstaedt J, Eastell R., on behalf of the SABRE Investigators. University of Michigan Comprehensive Cancer Center, Ann Arbor, MI; University of Sheffield, Sheffield, United Kingdom; AstraZeneca, Macclesfield, Cheshire, United Kingdom; Site Hospitalier Nord de Nantes, France; University of Alberta, Edmonton, AB, Canada; University of Stellenbosch, Tygerberg, South Africa

Background: Aromatase inhibitors in postmenopausal women have been associated with increased bone turnover and reduction in bone mineral density (BMD). SABRE (NCT00082277) is an ongoing, multicenter, Phase III/IV study evaluating the effects of the bisphosphonate, risedronate sodium, on BMD and bone turnover in postmenopausal women with hormone receptor-positive early breast cancer (EBC) treated with anastrozole. Materials and methods: Patients were stratified according to baseline risk of fracture by lumbar spine and hip T-scores (calculated from baseline BMD): higher risk (HR) = T-score <-2.0 and/or history of fracture; moderate risk (MR) = T-score <-1.0 but -2.0; and lower risk (LR) = T-score -1.0. HR patients received open-label anastrozole (1 mg/day) plus risedronate (35 mg/week) orally. MR patients were randomized in a double-blind manner to receive anastrozole plus either risedronate or placebo. LR patients received open-label anastrozole only. All patients received calcium and vitamin D supplements. Assessment of bone turnover was performed at baseline, 3, and 6 months using the bone formation markers serum procollagen type I amino terminal peptide (PINP) and bone alkaline phosphatase (bone ALP) and the bone resorption marker serum C terminal crosslinking telopeptide of type I collagen (sCTX). The planned, blinded interim analysis of bone markers from baseline to 6 months is presented here. P-values are based on logtransformed mean changes. Results: 234 patients received treatment.

Fulvestrant (n=270)aExemestane (n=270)aP-value
ORR, n (%)20 (7.4)18 (6.7)0.7364
CBR, n (%)87 (32.2)85 (31.5)0.8534
aOnly includes patients with measurable disease.


LR patients experienced a significant increase in sCTX (p=0.05), but no significant changes in PINP and bone ALP. There were significant decreases in all bone markers for HR patients (p<0.0001). In the MR group, all markers were significantly reduced in patients receiving anastrozole plus risedronate compared with anastrozole plus placebo (p<0.0001). Conclusion: We have shown for the first time that risedronate reduces bone turnover in anastrozole-treated postmenopausal women with hormone-receptor positive EBC and a preexisting moderate or higher risk of fracture.

Saturday, December 16, 2006 7:00 AM

Poster Session IV: Treatment: Endocrine Therapy (7:00 AM-9:00 AM)

 

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