Multiple vertebral fractures after suspension of denosumab. A series of 56 cases

On-time denosumab dosing recovered rapidly during the COVID-19 pandemic, yet remains suboptimal

Timely administration of denosumab every 6 mo is critical in osteoporosis treatment to avoid multiple vertebral fracture risk upon denosumab discontinuation or delay. This study aimed to estimate the immediate and prolonged impact of the COVID-19 pandemic on the timing of denosumab doses. We identified older adults (≥66 yr) residing in the community who were due to receive denosumab between January 2016 and December 2020 using Ontario Drug Benefit data. We completed an interrupted time-series analysis to estimate the impact of the COVID-19 pandemic (March 2020) on the monthly proportion of on-time denosumab doses (183 +/-30 d). Analyses were stratified by user type: patients due for their second dose (novice users), third or fourth dose (intermediate users), or ≥5th dose (established users). In additional analyses, we considered patients living in nursing homes, switching to other osteoporosis drugs, and reported trends until February 2022. We studied 148 554 patients (90.9% female, mean [SD] age 79.6 [8.0] yr) receiving 648 221 denosumab doses. The average pre-pandemic proportion of on-time therapy was steady in the community, yet differed by user type: 64.9% novice users, 72.3% intermediate users, and 78.0% established users. We identified an immediate overall decline in the proportion of on-time doses across all user types at the start of the pandemic: -17.8% (95% CI, -19.6, -16.0). In nursing homes, the pre-pandemic proportion of on-time therapy was similar across user types (average 83.5%), with a small decline at the start of the pandemic: -3.2% (95% CI, -5.0, -1.2). On-time therapy returned to pre-pandemic levels by October 2020 and was not impacted by therapy switching. Although on-time dosing remains stable as of February 2022, approximately one-fourth of patients in the community do not receive denosumab on-time. In conclusion, although pandemic disruptions to denosumab dosing were temporary, levels of on-time therapy remain suboptimal.

Methodological guidance for the use of real-world data to measure exposure and utilization patterns of osteoporosis medications

Observational studies of osteoporosis medications can provide critical real-world evidence (RWE) that fills knowledge gaps left by clinical trials. However, careful consideration of study design is needed to yield reliable estimates of association. In particular, obtaining valid measurements of exposure to osteoporosis medications from real-world data (RWD) sources is complicated due to different medication classes, formulations, and routes of administration, each with different pharmacology. Extended half-lives of bisphosphonates and extended dosing of denosumab and zoledronic acid require particular attention. In addition, prescribing patterns and medication taking behavior often result in gaps in therapy, switching, and concomitant use of osteoporosis therapies. In this review, we present important considerations and provide specialized guidance for measuring osteoporosis drug exposures in RWD. First, we compare different sources of RWD used for osteoporosis drug studies and provide guidance on identifying osteoporosis medication use in these data sources. Next, we provide an overview of osteoporosis pharmacology and how it can influence decisions on exposure measurement within RWD. Finally, we present considerations for the measurement of osteoporosis medication exposure, adherence, switching, long-term exposures, and drug holidays using RWD. Ultimately, a thorough understanding of the differences in RWD sources and the pharmacology of osteoporosis medications is essential to obtain valid estimates of the relationship between osteoporosis medications and outcomes, such as fractures, but also to improve the critical appraisal of published studies.

Maintenance of bone resorption markers in the low premenopausal range during the year following denosumab discontinuation is associated to bone density preservation. The ReoLaus study

PURPOSE

Denosumab discontinuation (DD) is associated with serum C-terminal X-linked telopeptides (sCTX) increase, bone mineral density (BMD) loss and vertebral fractures (VFs) risk increase. We compared clinical characteristics of women losing or not lumbar spine (LS) BMD one-year after DD, and their sCTX values at different time-points.

METHODS

We included women from the ReoLaus cohort having received ≥2 denosumab 60 mg injections, with three BMD measurements on the same device (before (DXA1), at the end of denosumab treatment (DXA2), and one-year after (DXA3)) and sCTX measured at different time-points. Losers (LS DXA3-DXA2 > 2.8 %) and stable groups were compared.

RESULTS

63 postmenopausal women were included (mean age 64.2 ± 9.1 years, 7.9 ± 2.7 denosumab injections). 19 months after last denosumab injection, 65 % had lost LS BMD. Losers were younger, had lower BMD and higher sCTX before denosumab, received more injections and gained more BMD under denosumab, and had higher sCTX after DD. Same proportion of patients received bisphosphonates in both groups, but 11 (all in losers group) received ≥1 zoledronate infusion. Three women developed VFs in the losers group (none in the stable). Mean sCTX at 10 and 19 months were 590 ± 372 versus 221 ± 101, and 598 ± 324 versus 293 ± 157 ng/l, respectively (premenopausal range < 573 ng/l, p < 0.01 for both). LS BMD loss and sCTX levels measured at 10 and 19 months were correlated (r² = 0.29, p = 0.10, and r² = 0.16, p < 0.005).

CONCLUSION

Maintenance of BMD gained with denosumab is associated with sCTX in the low premenopausal range after DD. Whether this could be achieved by regular sCTX monitoring and adjustment of bisphosphonates doses or frequency administration needs to be confirmed by further studies.

When and how to stop denosumab therapy in a patient with osteoporosis

Denosumab is a human monoclonal antibody that competitively inhibits the receptor activator of nuclear factor kappa B ligand which regulates osteoclast activity. It is an effective treatment for osteoporosis with a reduced cumulative rate of vertebral fractures, hip and nonvertebral fractures as well as an increase in bone mineral density. The benefits have been shown to be maintained when treatment is continued up to and likely after 10 years of therapy, but the effects are lost rapidly if treatment is discontinued abruptly. There are rare medical indications for discontinuation of treatment. Discontinuation of denosumab is often driven by concern about complications such as osteonecrosis of the jaw, atypical femoral fractures and hypocalcaemia, which remain rare events. Further studies are required to confirm safety and efficacy beyond 10 years of treatment, but it is likely that patients will have ongoing benefits from therapy beyond this. We aim to present a personal perspective of why and how denosumab should be discontinued in patients with osteoporosis.

Drug therapy for osteoporosis in older adults

The goal of osteoporosis management is to prevent fractures. Several pharmacological agents are available to lower fracture risk, either by reducing bone resorption or by stimulating bone formation. Bisphosphonates are the most widely used anti-resorptives, reducing bone turnover markers to low premenopausal concentrations and reducing fracture rates (vertebral by 50-70%, non-vertebral by 20-30%, and hip by ~40%). Bisphosphonates bind avidly to bone mineral and have an offset of effect measured in months to years. Long term, continuous use of oral bisphosphonates is usually interspersed with drug holidays of 1-2 years, to minimise the risk of atypical femoral fractures. Denosumab is a monoclonal antibody against RANKL that potently inhibits osteoclast development and activity. Denosumab is administered by subcutaneous injection every 6 months. Anti-fracture effects of denosumab are similar to those of the bisphosphonates, but there is a pronounced loss of anti-resorptive effect from 7 months after the last injection, which can result in clusters of rebound vertebral fractures. Two classes of anabolic drugs are now available to stimulate bone formation. Teriparatide and abaloparatide both target the parathyroid hormone-1 receptor, and are given by daily subcutaneous injection for up to 2 years. Romosozumab is an anti-sclerostin monoclonal antibody that stimulates bone formation and inhibits resorption. Romosozumab is given as monthly subcutaneous injections for 1 year. Head-to-head studies suggest that anabolic agents have greater anti-fracture efficacy and produce larger increases in bone density than anti-resorptive drugs. The effects of anabolic agents are transient, so transition to anti-resorptive drugs is required. The optimal strategy for cycling anabolics, anti-resorptives, and off-treatment periods remains to be determined.