Odanacatib in the treatment of postmenopausal women with low bone mineral density: three-year continued therapy and resolution of effect.

The selective cathepsin K inhibitor odanacatib (ODN) progressively increased bone mineral density (BMD) and decreased bone-resorption markers during 2 years of treatment in postmenopausal women with low BMD. A 1-year extension study further assessed ODN efficacy and safety and the effects of discontinuing therapy. In the base study, postmenopausal women with BMD T-scores between -2.0 and -3.5 at the lumbar spine or femur received placebo or ODN 3, 10, 25, or 50 mg weekly. After 2 years, patients (n = 189) were rerandomized to ODN 50 mg weekly or placebo for an additional year. Endpoints included BMD at the lumbar spine (primary), total hip, and hip subregions; levels of bone turnover markers; and safety assessments. Continued treatment with 50 mg of ODN for 3 years produced significant increases from baseline and from year 2 in BMD at the spine (7.9% and 2.3%) and total hip (5.8% and 2.4%). Urine cross-linked N-telopeptide of type I collagen (NTx) remained suppressed at year 3 (-50.5%), but bone-specific alkaline phosphatase (BSAP) was relatively unchanged from baseline. Treatment discontinuation resulted in bone loss at all sites, but BMD remained at or above baseline. After ODN discontinuation at month 24, bone turnover markers increased transiently above baseline, but this increase largely resolved by month 36. There were similar overall adverse-event rates in both treatment groups. It is concluded that 3 years of ODN treatment resulted in progressive increases in BMD and was generally well tolerated. Bone-resorption markers remained suppressed, whereas bone-formation markers returned to near baseline. ODN effects were reversible: bone resorption increased transiently and BMD decreased following treatment discontinuation.

Odanacatib, a cathepsin-K inhibitor for osteoporosis: a two-year study in postmenopausal women with low bone density.

Cathepsin K, a cysteine protease expressed in osteoclasts, degrades type 1 collagen. Odanacatib selectively and reversibly inhibited cathepsin K and rapidly decreased bone resorption in preclinical and phase I studies. A 1-year dose-finding trial with a 1-year extension on the same treatment assignment was performed in postmenopausal women with low bone mineral density (BMD) to evaluate the safety and efficacy of weekly doses of placebo or 3, 10, 25, or 50 mg of odanacatib on BMD and biomarkers of skeletal remodeling. Women with BMD T-scores of -2.0 or less but not less than -3.5 at the lumbar spine or femoral sites were randomly assigned to receive placebo or one of four doses of odanacatib; all received vitamin D with calcium supplementation as needed. The primary endpoint was percentage change from baseline lumbar spine BMD. Other endpoints included percentage change in BMD at hip and forearm sites, as well as changes in biomarkers of skeletal remodeling. Twenty-four months of treatment produced progressive dose-related increases in BMD. With the 50-mg dose of odanacatib, lumbar spine and total-hip BMD increased 5.5% and 3.2%, respectively, whereas BMD at these sites was essentially unchanged with placebo (-0.2% and -0.9%). Biochemical markers of bone turnover exhibited dose-related changes. The safety and tolerability of odanacatib generally were similar to those of placebo, with no dose-related trends in any adverse experiences. In summary, 2 years of weekly odanacatib treatment was generally well-tolerated and increased lumbar spine and total-hip BMD in a dose-related manner in postmenopausal women with low BMD.

Effects of continuing or stopping alendronate after 5 years of treatment: the Fracture Intervention Trial Long-term Extension (FLEX): a randomized trial.

CONTEXT: The optimal duration of treatment of women with postmenopausal osteoporosis is uncertain. OBJECTIVE: To compare the effects of discontinuing alendronate treatment after 5 years vs continuing for 10 years. DESIGN AND SETTING: Randomized, double-blind trial conducted at 10 US clinical centers that participated in the Fracture Intervention Trial (FIT). PARTICIPANTS: One thousand ninety-nine postmenopausal women who had been randomized to alendronate in FIT, with a mean of 5 years of prior alendronate treatment. INTERVENTION: Randomization to alendronate, 5 mg/d (n = 329) or 10 mg/d (n = 333), or placebo (n = 437) for 5 years (1998-2003). MAIN OUTCOME MEASURES: The primary outcome measure was total hip bone mineral density (BMD); secondary measures were BMD at other sites and biochemical markers of bone remodeling. An exploratory outcome measure was fracture incidence. RESULTS: Compared with continuing alendronate, switching to placebo for 5 years resulted in declines in BMD at the total hip (-2.4%; 95% confidence interval [CI], -2.9% to -1.8%; P<.001) and spine (-3.7%; 95% CI, -4.5% to -3.0%; P<.001), but mean levels remained at or above pretreatment levels 10 years earlier. Similarly, those discontinuing alendronate had increased serum markers of bone turnover compared with continuing alendronate: 55.6% (P<.001) for C-telopeptide of type 1 collagen, 59.5% (P < .001) for serum n = propeptide of type 1 collagen, and 28.1% (P<.001) for bone-specific alkaline phosphatase, but after 5 years without therapy, bone marker levels remained somewhat below pretreatment levels 10 years earlier. After 5 years, the cumulative risk of nonvertebral fractures (RR, 1.00; 95% CI, 0.76-1.32) was not significantly different between those continuing (19%) and discontinuing (18.9%) alendronate. Among those who continued, there was a significantly lower risk of clinically recognized vertebral fractures (5.3% for placebo and 2.4% for alendronate; RR, 0.45; 95% CI, 0.24-0.85) but no significant reduction in morphometric vertebral fractures (11.3% for placebo and 9.8% for alendronate; RR, 0.86; 95% CI, 0.60-1.22). A small sample of 18 transilial bone biopsies did not show any qualitative abnormalities, with bone turnover (double labeling) seen in all specimens. CONCLUSIONS: Women who discontinued alendronate after 5 years showed a moderate decline in BMD and a gradual rise in biochemical markers but no higher fracture risk other than for clinical vertebral fractures compared with those who continued alendronate. These results suggest that for many women, discontinuation of alendronate for up to 5 years does not appear to significantly increase fracture risk. However, women at very high risk of clinical vertebral fractures may benefit by continuing beyond 5 years. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT 00398931.

Changes in bone density and turnover after alendronate or estrogen withdrawal.

OBJECTIVE: To compare bone mineral density (BMD) and bone turnover changes after therapy withdrawal in postmenopausal women treated with alendronate or estrogen-progestin. DESIGN: In this randomized, blinded, multinational, placebo-controlled trial, 1,609 healthy postmenopausal women ages 45 to 59 years were assigned to receive alendronate, placebo, or open-label estrogen-progestin (conjugated equine estrogens plus medroxyprogesterone acetate or a cyclic regimen of 17 beta-estradiol, norethisterone acetate and estradiol). Of the original women, one third after year 2 and one third after year 4 were switched from alendronate to placebo, while remaining blinded to treatment assignment. The women taking estrogen-progestin in years 1 to 4 were followed off therapy in years 5 and 6. BMD at the lumbar spine and hip and biochemical markers of bone turnover were measured. RESULTS: The treatment groups described in the current report represent 860 women at baseline; 481 women entered year 5, and 430 completed 6 years. BMD steadily decreased in the placebo group during all 6 years. In contrast, spine and hip BMD increased during the first 4 years in the groups receiving daily continuous alendronate 5 mg and estrogen-progestin. During years 5 and 6, BMD decreased at the lumbar spine -2.42% (95% CI = -4.10, -0.74) and total hip -1.09% (-2.60, 0.41) in the group previously treated with alendronate 5 mg for 4 years. In comparison, large BMD decreases were observed at the spine [-7.69% (-8.96, -6.41)] and total hip [-5.16% (-6.30, -4.01)] among women who had received estrogen-progestin for 4 years. CONCLUSION: Alendronate produces greater residual skeletal effects than estrogen-progestin after therapy discontinuation.