Merck Provides New Data From Phase IIB Clinical Study Of Odanacatib

Merck has provided new data from a phase IIB clinical study of odanacatib, oral, once-weekly investigational treatment for osteoporosis. The data showed that when stopping treatment after two years, the increases in lower back (lumbar spine) bone mineral density (BMD) were reversed over the next year, while BMD at the hip (femoral neck) remained above levels observed at the start of the study.

Reportedly, three years of treatment with odanacatib 50mg demonstrated increases in BMD at key fracture sites and minimal impact on the formation of new bone as measured by biochemical markers of bone turnover. Odanacatib is currently in phase III clinical trials and is being evaluated in a large-scale, global outcomes study to determine its effects on vertebral, hip and non-vertebral fractures.

Odanacatib is a cathepsin inhibitor that selectively inhibits the cathepsin enzyme. Inhibition of cathepsin is a novel approach to the treatment of osteoporosis.

A one-year extension study was conducted following the completion of a two-year phase IIB study in which odanacatib 50mg was shown to increase BMD and decrease bone resorption in postmenopausal women with low BMD.

Of the 399 women in the two-year study 189 women continued into the extension study and were re-randomised to odanacatib 50mg once weekly or placebo for an additional year. In addition, all women received open-label supplementation with Vitamin D3, 5600 IU weekly, and those with total calcium intake (dietary plus supplemental) below 1000mg per day received open-label 500mg daily calcium supplements.

Of the 189 extension study participants, 169 patients completed three years of treatment, and 20 dropped out of the study. Reasons for early discontinuation were similar among odanacatib and placebo groups. All patients who completed the third year of treatment were included in the BMD efficacy analyses, all 189 women were included in the safety analyses.

Art Santora II, executive director of clinical research at Merck Research Labs, said: “The ‘rapid off’ effect results showed that the drug’s effect did not persist long after the drug cleared the body. Additionally, the continued increases in BMD seen at three years while sparing bone formation adds to the existing scientific evidence for the potential of odanacatib as a novel treatment option for osteoporosis.”