Abaloparatide is an Effective Treatment Option for Postmenopausal Osteoporosis: Review of the Number Needed to Treat Compared with Teriparatide

Abstract

Abaloparatide (ABL) is a 34-amino acid peptide designed to be a selective activator of the parathyroid hormone receptor type 1 signaling pathway. In the Abaloparatide Comparator Trial In Vertebral Endpoints (ACTIVE), subcutaneous ABL reduced the risk of new vertebral, nonvertebral, clinical, and major osteoporotic fracture compared with placebo and of major osteoporotic fracture compared with teriparatide. To further evaluate the effectiveness of ABL, we calculated the number needed to treat (NNT) to prevent one fracture using ACTIVE data. To estimate the potential effectiveness of ABL in populations at higher fracture risk than in ACTIVE, we calculated NNT for vertebral fracture using reference populations from historical placebo-controlled trials, assuming an 86% relative risk reduction in vertebral fracture with ABL treatment as observed in ACTIVE. NNT was calculated as the reciprocal of the absolute risk reduction in ACTIVE. The projected NNT for ABL in other populations was calculated based on incidence rate (IR) for vertebral fractures in the placebo arms of the FREEDOM (placebo IR 7.2%), FIT-1 (placebo IR 15.0%), and FIT-2 (placebo IR 3.8%) trials. NNT for ABL in ACTIVE was 28 for vertebral, 55 for nonvertebral, 37 for clinical, and 34 for major osteoporotic fracture. NNT for these fracture types for teriparatide in ACTIVE were 30, 92, 59, and 75, respectively. Using placebo IRs from FREEDOM, FIT-1, and FIT-2, projected NNTs for vertebral fracture with ABL were 17, 8, and 31. These data are useful for further evaluating ABL for the treatment of osteoporosis in postmenopausal women.

Keywords: ACTIVE trial; Abaloparatide; Fracture risk reduction; Number needed to treat; Postmenopausal osteoporosis.

Fig. 1

Number needed to treat, by fracture type, after 18 months of treatment with abaloparatide or teriparatide in ACTIVE

Fig. 2

Projected number needed to treat with ABL based on incidence rates reported in populations with varying placebo-group incidence rates of new vertebral fracture. NNTs included for denosumab and for alendronate are as reported in FREEDOM [10], FIT-1 [11], and FIT-2 [12]. ABL abaloparatide, IR incidence rate, NNT number needed to treat, PBO placebo.