Abaloparatide

Abaloparatide (brand name Tymlos; formerly BA058) is a parathyroid hormone-related protein (PTHrP) analog drug used to treat osteoporosis. Like the related drug teriparatide, and unlike bisphosphonates, it is an anabolic (i.e., bone growing) agent. On 28 April 2017, it was approved by the Food and Drug Administration (FDA) to treat postmenopausal osteoporosis. Abaloparatide (brand name Tymlos; formerly BA058) is a parathyroid hormone-related protein (PTHrP) analog drug used to treat osteoporosis. Like the related drug teriparatide, and unlike bisphosphonates, it is an anabolic (i.e., bone growing) agent. On 28 April 2017, it was approved by the Food and Drug Administration (FDA) to treat postmenopausal osteoporosis. Abaloparatide is indicated to treat postmenopausal women with osteoporosis who are at high risk of bone fractures. The dose recommended is 80mcg subcutaneous injection once a day, administered in the periumbilical area using a prefilled pen device containing 30 doses. Preclinical studies revealed that abaloparatide systemic daily administration leads to a dose- and time-dependent increase in the incidence of osteosarcoma in rodents. However, whether abaloparatide-SC will cause osteosarcoma in humans is unknown. Thus, the use of abaloparatide is not recommended for individuals at increased risk of osteosarcoma. Additionally, its use is not advised for more than 2 years during a patient's lifetime. The most common side effects reported by more than 2% of clinical trials subjects are hypercalciuria, dizziness, nausea, headache, palpitations, fatigue, upper abdominal pain and vertigo. Abaloparatide is 34 amino acid synthetic analog of PTHrP. It has 41% homology to parathyroid hormone (PTH) (1-34) and 76% homology to parathyroid hormone-related protein (PTHrP) (1-34). It works as an anabolic agent for the bone, through selective activation of the parathyroid hormone 1 receptor (PTH1R), a G protein-coupled receptor (GPCR) expressed in the osteoblasts and osteocytes. Abaloparatide preferentially binds the RG conformational state of the PTH1R, which in turn elicits a transient downstream cyclic AMP signaling response towards to a more anabolic signaling pathway. Abaloropatide was known as BIM-44058 when it was first discovered at Ipsen and as BA058 while under development. The anabolic effects of abaloparatide on bone were demonstrated in two preclinical studies conducted in ovarectomized rats. Both studies showed increased cortical and trabecular bone volume and density, and trabecular microarchitecture improvement in vertebral and nonvertebral bones after short-term and long-term daily subcutaneous injection of abaloparatide compared to controls. Recent studies indicated a dose-dependent increased in bone mass and strength in long-term abalorapatide treatment. However, it was also found that prolonged abalorapatide-SC treatment leads to increased incidence of osteosarcoma. To date, there is no evidence for increased risk of bone tumors due to prolonged systemic administration in humans. Based on preclinical data, the FDA does not advised the use of abaloparatide-SC for more than 2 years, or in patients with history of Paget disease and/or other conditions that exacerbates the risk of developing osteosarcoma. Phase II trials were initiated in 2008. A 24-week randomized trial was conducted in postmenopausal women with osteoporosis (n=222) assessing bone mass density (BMD) changes as the primary endpoint. Significant BMD increase at doses of 40 and 80 mcg were found in the lumbar spine, femur and hips of abaloparatide-treated participants compared to placebo. Additionally, abaloparatide showed superior anabolic effects on the hips compared to teriparatide. In the phase III (2011-2014) Abaloparatide Comparator Trial in Vertebral Endpoints (ACTIVE) trial, an 18-months randomized, multicenter, double-blinded, placebo-controlled study evaluated the long-term efficacy of abaloparatide compared to placebo and teriparatide in 2,463 postmenopausal women (± 69 years old). Women who received daily injections of abaloparatide experienced substantial reduction in the incidence of fractures compared to placebo. Additionally, greater BMD increase at 6, 12 and 18 months in spinal, hips and femoral bones was observed in abaloparatide compared to placebo and teriparatide-treated subjects.