Multiple Vertebral Fractures Following Denosumab Discontinuation: Are We Exaggerating?

The Role of Bisphosphonates Prior to Denosumab Treatment on Rebound Fractures: A Mini Review

Denosumab is a potent anti-resorptive medication used to treat patients at high risk for osteoporosis; however, its beneficial effects on the skeletal system are quickly reversed after discontinuation. In contrast, bisphosphonates (BPs) are anti-resorptive agents with residual effects on the bone matrix; thus, these are capable of preserving bone mass for a long time. Therefore, subsequent anti-resorptive treatment with BPs is mandatory to prevent rebound fractures. Furthermore, BP administration before denosumab treatment appears to be a reasonable strategy for reducing hyperactivation of bone remodeling. In this review, we summarize the effects of BP administration before denosumab treatment in preventing rebound fractures after denosumab discontinuation.

Does the VDR gene polymorphism influence the efficacy of denosumab therapy in postmenopausal osteoporosis?

INTRODUCTION

One of the challenges of personalized medicine is a departure from traditional pharmacology toward individualized, genotype-based therapies. Postmenopausal osteoporosis is a prevalent condition requiring intensive treatment, whose effects are measurable only after a long time, and the goal is bone fracture prevention. This study aimed to determine the influence of VDR gene variation on anti-osteoporotic one-year treatment with denosumab in 63 Polish women with postmenopausal osteoporosis.

MATERIALS AND METHODS

The correlation between bone mineral density (BMD) of the lumbar vertebral column (L1-L4) and femoral neck, and genotype distributions for the ApaI, BsmI, FokI, and TaqI variants of the VDR gene was analyzed. Bone fractures during denosumab therapy were also investigated.

RESULTS

In the case of the Bsml polymorphism, female patients with BB and Bb genotypes had statistically significantly higher values of BMD and T-score/Z-score indicators, which persisted after a year of denosumab treatment. Our results indicated that the Bsml polymorphism contributes to better bone status, and, consequently, to more efficient biological therapy. The study did not reveal significant differences between changes (delta) in BMD and genotypes for the analyzed VDR gene loci. In the entire study group, one bone fracture was observed in one patient throughout the yearlong period of denosumab therapy.

CONCLUSIONS

BB and Bb genotypes of the Bsml polymorphism of the VDR gene determine higher DXA parameter values both before and after one-year denosumab therapy in postmenopausal women with osteoporosis.

Persistence with osteoporosis treatment in patients from the Lille University Hospital Fracture Liaison Service

PURPOSE/INTRODUCTION

A Fracture Liaison Service (FLS) was set up at Lille University Hospital in 2016. The purpose of this study was to assess persistence with osteoporosis treatment in patients from the FLS over a period of 1 year, and to determine predictors of discontinuation.

METHODS

The study population comprised adults of both genders, aged 50 or over, admitted to Lille University Hospital between January 2016 and January 2019 for a low-trauma fracture and managed in our FLS. Outcomes included (1) persistence rate at 1 year after treatment initiation, (2) persistence rate at 2 years after treatment initiation, (3) persistence rate at 1 and 2 years after treatment initiation according to type of treatment, (4) predictors of non-persistence, and (5) reasons for discontinuing treatment over 1 year after initiation. Persistence was determined using the Kaplan-Meier method.

RESULTS

In all, 1224 patients (≥50 years old) with a recent history of low-trauma fracture (≤12 months) were identified. Of these, 380 patients - 79.2% female; mean (SD) age 76 (11) years - were seen at the FLS. In those 380 patients, 410 fractures were found and 360 of them (87.8%) were major fractures, breaking down as follows: vertebra (44%), hip (19%), proximal humerus (10%), and pelvis (8%). Osteoporosis treatment was prescribed for 367 (96.6%) patients and 275 of them began the prescribed treatment. The following anti-osteoporosis drugs were prescribed: zoledronic acid (n=150, 54.5%), teriparatide (n=63, 22.9%), and denosumab (n=39, 14.2%). Oral bisphosphonates were prescribed for a few patients (n=23, 8.4%). Persistence with osteoporosis medication (any class) was estimated at 84.1% (95% CI: 79.1% to 88.1%) at 12-month follow-up, and dropped to 70.3% (95% CI: 63.7% to 75.9%) at 24 months. When drug-specific analyses were performed using the Kaplan-Meier method, persistence rates at 12 and 24 months were found to be higher with denosumab than with any other treatment. Independent predictors of non-persistence at 12 months were 'follow-up performed by a general practitioner (GP)' - Odds Ratio (OR) for GP vs. FLS = 3.68; 95% CI, 1.52 to 8.90, p=0.004 - and 'treatment with zoledronic acid' - OR for zoledronic acid vs. denosumab = 3.39; 95% CI, 1.21 to 9.50, p=0.019; OR for zoledronic acid vs. teriparatide = 8.86; 95% CI, 1.15 to 68.10, p=0.035.

CONCLUSIONS

This study provides evidence of the success of our FLS in terms of long-term persistence with osteoporosis treatments. However, osteoporosis treatment initiation still needs to be improved.

Fracture risk and management of discontinuation of denosumab therapy: a systematic review and position statement by ECTS

CONTEXT

Denosumab discontinuation is characterized by an increase in bone turnover overriding pre-treatment status, a rapid bone loss in the majority and multiple vertebral fractures (VFx) in some patients.

METHODS

A working group of the European Calcified Tissue Society (ECTS) performed an updated systematic review of existing literature on changes of bone turnover, bone mineral density (BMD), and fracture risk after denosumab discontinuation and provided advice on management based on expert opinion.

RESULTS

Important risk factors for multiple VFx following denosumab cessation are prevalent VFx, longer duration off therapy, greater gain in hip BMD during therapy, and greater loss of hip BMD after therapy according to a retrospective analysis of the FREEDOM Extension Study. Case series indicate that prior bisphosphonate therapy mitigates the biochemical rebound phenomenon after denosumab discontinuation, but it is uncertain whether this attenuation prevents BMD loss and fractures. Current evidence indicates partial efficacy of subsequent antiresorptive treatment with results seemingly dependent on duration of denosumab treatment.

CONCLUSIONS

A careful assessment of indications to start denosumab treatment is advised, especially for younger patients. A case for long-term treatment with denosumab can be made for patients at high fracture risk already on denosumab treatment given the favorable efficacy and safety profile. In case of denosumab discontinuation, alternative antiresorptive treatment should be initiated 6 months after the final denosumab injection. Assessment of bone turnover markers may help define the optimal regimen, pending results of ongoing RCTs. Patients having sustained VFx should be offered prompt treatment to reduce high bone turnover.

Alendronate after denosumab discontinuation in women previously exposed to bisphosphonates was not effective in preventing the risk of spontaneous multiple vertebral fractures: two case reports

At denosumab discontinuation, an antiresorptive agent is indicated to reduce the high bone turnover, the rapid bone loss, and the risk of spontaneous vertebral fractures. We report two cases of postmenopausal women, previously exposed to bisphosphonates, treated with alendronate at denosumab discontinuation. Alendronate was ineffective to avoid spontaneous clinical vertebral fractures. They presented three and nine spontaneous vertebral fractures 8 and 12 months after denosumab discontinuation, respectively. Ineffectiveness of alendronate was attributed to insufficient control of the rebound as assessed by B-crosslaps measures in the first case, and partially to the high risk of fractures in the later. In both situations, the increased fracture risk may have favoured these new fractures. It is urgent to define effective therapeutic strategies to avoid spontaneous vertebral fractures after denosumab discontinuation.

Vertebral fractures cascade: potential causes and risk factors

We performed a study to identify potential causes and risk factors of vertebral fracture cascade. Vertebral fracture cascade is a severe clinical event in patients with bone fragility. Only half of patients have an identified cause of secondary osteoporosis.

INTRODUCTION

Vertebral fracture (VF) is the most common osteoporotic fracture, and a strong risk factor of subsequent VFs leading to VF cascade (VFC). We prompted a study to identify potential causes and risk factors of VFC.

METHODS

VFC observations were collected retrospectively between January 2016 and April 2017. VFC was defined as an occurrence of at least three VFs within 1 year.

RESULTS

We included in 10 centers a total of 113 patients with VFC (79.6% of women, median age 73, median number of VFs in the cascade, 5). We observed 40.5% and 30.9% of patients with previous major fractures and a previous VF, respectively, and 68.6% with densitometric osteoporosis; 18.9% of patients were currently receiving oral glucocorticoids and 37.1% in the past. VFC was attributed by the physician to postmenopausal osteoporosis in 54% of patients. A secondary osteoporosis associated with the VFC was diagnosed in 52 patients: glucocorticoid-induced osteoporosis (25.7%), non-malignant hemopathies (6.2%), alcoholism (4.4%), use of aromatase inhibitors (3.6%), primary hyperparathyroidism (2.7%), hypercorticism (2.7%), anorexia nervosa (2.7%), and pregnancy and lactation-associated osteoporosis (1.8%). A total of 11.8% of cases were reported following a vertebroplasty procedure. A total of 31.5% patients previously received an anti-osteoporotic treatment. In six patients, VFC occurred early after discontinuation of an anti-osteoporotic treatment, in the year after the last dose effect was depleted: five after denosumab and one after odanacatib.

CONCLUSION

The results of this retrospective study showed that only half of VFC occurred in patients with a secondary cause of osteoporosis. Prospective studies are needed to further explore the determinants of this severe complication of osteoporosis.