Risk of Jaw Osteonecrosis After Intravenous Bisphosphonates in Cancer Patients and Patients Without Cancer

Genome-wide association study of osteonecrosis of the jaw in Danish patients receiving antiresorptive therapy for osteoporosis: A case-control study

Background

Prior studies of the pharmacogenomics of osteonecrosis of the jaw (ONJ) have had various methodological limitations, including using candidate gene selection as their sole strategy, a small number of ONJ cases, or a study population based on an oncology setting.

Objectives

The aim of our case-control study was to evaluate previously reported associations between genetic factors and ONJ, which were based on either genome-wide association studies (GWAS) or candidate gene approaches. Furthermore, we aimed to identify genetic risk factors for ONJ by using GWAS to determine single-nucleotide polymorphisms (SNPs) with statistically significant differences in frequency between ONJ patients and osteoporosis controls.

Methods

Patients with medically confirmed ONJ and who were registered in the Scandinavian Cohort of ONJ patients were included. Controls from the general population were matched on age (±5 years), sex, and cumulative antiresorptive drug exposure. The ONJ diagnosis date for cases corresponded to the index date for matched controls. DNA isolation, genotyping, and data analyses were performed by Q2/EA Genomics using standard protocols and best practices. Blood or tissue samples for 55 ONJ cases and 125 controls were collected. Due to the low quality of the tissue samples, final analyses were based on blood samples of 40 ONJ cases and 124 controls.

Results

We detected no significant genome-wide associations. Of the 43 SNPs with ONJ association in prior studies, none were replicated in our study.

Conclusions

Even though our study sample is the largest to date, we had limited statistical power for GWAS but adequate power for replication analyses. Our study provides no evidence for any genetic predisposition to ONJ. Future studies could increase their statistical power by combining ONJ GWAS datasets and by performing a meta-analysis or pursuing a sequencing strategy in order to identify rare variants.

Incidence and Risk Factors of Osteonecrosis of Femoral Head in Multiple Myeloma Patients Undergoing Dexamethasone-Based Regimens

Objectives

To investigate the incidence and risk factors for osteonecrosis of femoral head (ONFH) in multiple myeloma (MM) patients undergoing dexamethasone-based regimens (DBRs).

Methods

A retrospective study was conducted in MM patients administered DBRs between December 2012 and April 2015. Demographic, clinical, and laboratory data were extracted to compare between two groups. Incidence of ONFH were calculated and risk factors identified by both univariate and multivariate analysis.

Results

The study group comprised 105 patients undergoing DBRs. Seven patients with ONFH after DBRs were classified as the ONFH group, and the other 98 patients without ONFH were included in the non-ONFH group. Incidence of ONFH was 6.7%. Median age of developing ONFH was 51 years (45-64), and the male to female ratio was 6 : 1. A total of 12 femoral heads were involved, including unilateral in 2 patients and bilateral in 5 patients. After the multivariate analysis, four risk factors were confirmed including male, younger age, cumulative dose of dexamethasone, and hyperlipidemia.

Conclusion

The overall incidence of ONFH in MM patients treated with DBRs is 6.7%, and 4 risk factors are confirmed including male, younger age, cumulative dose of dexamethasone, and hyperlipidemia in our study.

Dietary countermeasure mitigates simulated spaceflight-induced osteopenia in mice

Spaceflight is a unique environment that includes at least two factors which can negatively impact skeletal health: microgravity and ionizing radiation. We have previously shown that a diet supplemented with dried plum powder (DP) prevented radiation-induced bone loss in mice. In this study, we investigated the capacity of the DP diet to prevent bone loss in mice following exposure to simulated spaceflight, combining microgravity (by hindlimb unloading) and radiation exposure. The DP diet was effective at preventing most decrements in bone micro-architectural and mechanical properties due to hindlimb unloading alone and simulated spaceflight. Furthermore, we show that the DP diet can protect osteoprogenitors from impairments resulting from simulated microgravity. Based on our findings, a dietary supplementation with DP could be an effective countermeasure against the skeletal deficits observed in astronauts during spaceflight.

Prevalence, initiating factor, and treatment outcome of medication-related osteonecrosis of the jaw-a 4-year prospective study

OBJECTIVES

Medication-related osteonecrosis of the jaw (MRONJ) has a wide range of prevalence, and a standard therapy has not yet been established. The aim of this study was to analyze the prevalence and initiating factors of MRONJ and the outcomes of surgical therapy.

STUDY DESIGN

In a prospective cohort study, all patients diagnosed with MRONJ in the Region of Skåne, in Sweden, were included. Predictor variables (comorbidity, site, stage, gender) and initiating factors (tooth extraction, periodontitis) were recorded. Surgical treatment was sequestrectomy or block resection, and the outcome variable was healing after 2 months. To estimate the prevalence, data on the use of bisphosphonate and denosumab were used.

RESULTS

Fifty-five patients with MRONJ were identified. The prevalence of MRONJ was 0.043% among patients treated with oral bisphosphonates, 1.03% among those on intravenous bisphosphonates and 3.64% in those on high-dose denosumab. Periodontal disease preceded development of MRONJ in 41 patients. Fifty patients were treated surgically and followed up for at least 2 months. Remission or healing occurred in 80% of patients treated with sequestrectomy and in 92.5% of patients treated with block resection.

CONCLUSIONS

The prevalence of MRONJ in Sweden is low. Periodontitis is the most common initiating factor. The outcome of treatment of MRONJ is healing in most patients treated surgically.