A Study to Assess the Safety and Efficacy of 3 Doses of ALX1-11 (50, 75, and 100µg) in the Treatment of Postmenopausal Osteoporosis

Human clinical experience with a synthetic human parathyroid hormone fragment (rhPTH 1-34) and animal studies with ALX1-11 demonstrate consistent increases in bone mineral density. Furthermore, the newly formed bone is normal in structure and composition. Therefore, ALX1-11 (recombinant human parathyroid hormone \[rhPTH 1-84\]) has the potential to stimulate new bone formation in osteoporotic patients thereby increasing trabecular bone density and preventing fractures. The clinical profile for ALX1-11 can be expected to be unique, since none of the approved therapies for osteoporosis are able to form the quantities of new bone that ALX1-11 is potentially capable of. Patients with bone density below the "fracture threshold" (osteopenia), as well as those with established vertebral fractures (osteoporosis), would be expected to benefit from treatment. Animal toxicology studies have been completed and there were no results to indicate any restrictions in the clinical usage of the drug. Preliminary human clinical experience with ALX1-11 in healthy, postmenopausal females has demonstrated no apparent risk of frank hypercalcemia\* at single administrations up to 5.0 µg/kg or daily administrations for 7 days up to 2.0 µg/kg/day. Based on these studies, the anticipated therapeutic range of ALX1-11 is 50-100 µg per day (approx. 1.0 - 1.5 µg/kg/day). Therefore, the dose range to be tested in this study will include an anticipated minimally effective dose, interim dose and maximally tolerable dose (50, 75 and 100 µg). The efficacy of 3 doses of ALX1-11 will be assessed in terms of bone mineral density and biochemical markers of bone turnover in postmenopausal women. The primary objective of this study is to determine the dose-response relationship of ALX1-11 in terms of bone mineral density. The efficacy of the 3 doses of ALX1-11 relative to placebo will be determined by measurement of bone mineral density (by DXA) at baseline and at 3, 6 and 12 months. Patients will administer a daily subcutaneous injection of 0.5 mL of either 50, 75 or 100 µg of ALX1-11 or placebo every morning for 12 months. Women will be advised to use the provided calcium supplements (500mg elemental calcium) to maintain a total daily intake of 1000-1500 mg/day and vitamin D supplements will also be provided (400 IU/day). A dietary questionnaire will be done at visit screen, 6 and 15. If a patient's total serum calcium measurement, during the treatment phase, demonstrates frank hypercalcemia OR if her pre-dose calcium levels are more than 0.5 mg/dL or 0.125 mmol/L above the upper limit of normal (2.78 mmol/L or 11.1 mg/dL), then the patient's serum calcium level must be repeated. If upon re-test a patient continues to demonstrate frank hypercalcemia OR if her basal pre-dose calcium levels continues to be elevated above the upper limit of normal, then the patient will be withdrawn from the study. \*Frank Hypercalcemia: defined as total serum calcium levels above 11.1 mg/dL or 2.78 mmol/L