Abaloparatide

Overview

Abaloparatide is an FDA-approved anabolic bone-building agent and synthetic analog of parathyroid hormone-related protein (PTHrP). It selectively activates the PTH1 receptor to stimulate new bone formation while minimizing bone resorption. In the phase III ACTIVE trial, abaloparatide showed superior BMD increases at the hip compared to teriparatide, with substantial fracture risk reduction. It was approved in the US in 2017 and EU in 2022 for postmenopausal women and men with osteoporosis at high fracture risk.

Mechanism of action

Abaloparatide works through selective activation of the parathyroid hormone 1 receptor (PTH1R), a G protein-coupled receptor expressed on osteoblasts and osteocytes. It preferentially binds to the RG (relaxed, G-protein-coupled) conformational state of PTH1R, which elicits a transient downstream cyclic AMP signaling response favoring anabolic bone formation over resorption. This selective binding pattern produces more bone-building activity with less hypercalcemic effect compared to native PTH. The result is increased cortical and trabecular bone volume, density, and improved microarchitecture.

Key research findings

• FDA-approved for osteoporosis treatment
• Actively builds new bone (anabolic mechanism)
• Superior hip BMD gains vs teriparatide in trials
• Reduces vertebral fracture risk significantly
• Reduces nonvertebral fracture risk
• Lower hypercalcemia risk than teriparatide
• Works through selective PTH1R activation
• Benefits seen within 6 months

Research applications

Osteoporosis (FDA-Approved)

• Postmenopausal Osteoporosis — FDA-approved for postmenopausal women with osteoporosis at high risk for fracture or who have failed other therapies.
• Male Osteoporosis — FDA-approved for men with osteoporosis at high risk for fracture or intolerant to other treatments.

Bone Health Research

• Fracture Prevention — Phase III trials demonstrated substantial reduction in vertebral and nonvertebral fractures.
• Sequential Therapy — ACTIVExtend trial showed benefits of abaloparatide followed by alendronate for maintained bone protection.