The Role of Antiangiogenic Therapy in the Development of Osteonecrosis of the Jaw

There is an increasing use of established and newer medications that have antiangiogenic properties. Inhibition of angiogenesis likely has either a primary or secondary role in the development of osteonecrosis of the jaw (ONJ). These medications are being used in the treatment of various cancers and in the treatment of several non-oncologic conditions. Antiangiogenic medications when used in combination with antiresorptive medications, such as nitrogen-containing bisphosphonates or denosumab, seem to increase the likelihood of osteonecrosis of the jaw. This review highlights the role of inhibitors of angiogenesis and their role in the development of osteonecrosis of the jaws.

Bisphosphonates in inflammatory rheumatic diseases

The main well recognized action of bisphosphonates (BPs) is their antiresorptive capacity, making them first-line drugs in the treatment of osteoporosis and other metabolic bone diseases. In this review we have compiled other possible actions of BPs, particularly in the areas of immunomodulation, anti-inflammatory capacity and in the prevention of structural joint damage in inflammatory rheumatic diseases. The immunomodulatory capacity of BPs has been focused on the mechanisms involved in the acute-phase response associated with the administration of nitrogen containing BPs (N-BPs), with the stimulus of pro-inflammatory cytokines, through the mevalonate pathway, activation of T-cells and the decrease in the cytotoxic T-lymphocyte antigen-4 (CTLA-4). In relation to their anti-inflammatory capacity, special attention has been given to their effect on preventing structural damage in inflammatory joint diseases and on the differential immune response in bone lesions of the most common and representative inflammatory rheumatic diseases, i.e. rheumatoid arthritis and spondyloarthropathies. The present data indicate that more studies are needed to improve the knowledge on the effect of BPs on inflammatory-mediated diseases and particularly on the prevention and/or treatment of the structural damage in these disorders, since these agents could be a potential useful concomitant therapy.

Zoledronic Acid in a Mouse Model of Human Fibrous Dysplasia: Ineffectiveness on Tissue Pathology, Formation of "Giant Osteoclasts" and Pathogenetic Implications

We compared the effects of a nitrogen-containing bisphosphonate (N-BP), zoledronic acid (ZA), and an anti-mouse RANKL antibody (anti-mRANKL Ab) on the bone tissue pathology of a transgenic mouse model of human fibrous dysplasia (FD). For comparison, we also reviewed the histological samples of a child with McCune-Albright syndrome (MAS) treated with Pamidronate for 3 years. EF1α-Gsα^R201C mice with FD-like lesions in the tail vertebrae were treated with either 0.2 mg/kg of ZA at day 0, 7, and 14 or with 300 μg/mouse of anti-mRANKL Ab at day 0 and 21. All mice were monitored by Faxitron and histological analysis was performed at day 42. ZA did not affect the progression of the radiographic phenotype in EF1α-Gsα^R201C mice. FD-like lesions in the ZA group showed the persistence of osteoclasts, easily detectable osteoclast apoptotic activity and numerous "giant osteoclasts". In contrast, in the anti-mRANKL Ab-treated mice, osteoclasts were markedly reduced/absent, the radiographic phenotype reverted and the FD-like lesions were extensively replaced by newly formed bone. Numerous "giant osteoclasts" were also detected in the samples of the child with MAS. This study supports the hypothesis that osteoclasts per se, independently of their resorptive activity, are essential for development and expansion of FD lesions.

Effect of Bone Resorption Inhibitors on Serum Cholesterol Level and Fracture Risk in Osteoporosis: Randomized Comparative Study Between Minodronic Acid and Raloxifene

The positive link between osteoporosis and hypercholesterolemia has been documented, and bone resorption inhibitors, such as nitrogen-containing bisphosphonates (N-BP) and selective estrogen receptor modulators (SERMs), are known to reduce serum cholesterol levels. However, the relationship between the baseline cholesterol level and incident fracture rate under the treatment using the bone resorption inhibitors has not been documented. We investigated the relation between vertebral fracture incident and the baseline cholesterol levels and cholesterol-lowering effect of N-BP and SERM in osteoporosis through a prospective randomized open-label study design. Patients with osteoporosis (n = 3986) were allocated into two groups based on the drug used for treatment: minodronic acid (MIN) (n = 1624) as an N-BP and raloxifene (RLX) as an SERM (n = 1623). Serum levels of cholesterol and incidence of vertebral fracture were monitored for 2 years. The vertebral fracture rates between the two groups were compared using the pre-specified stratification factors. The patients receiving MIN with baseline low-density lipoprotein (LDL)-cholesterol level of ≥ 140 mg/dL, high-density lipoprotein cholesterol level < 40 mg/dL, age group of ≥ 75 years, and T score of BMD ≥ -3 SD had significantly lower vertebral fracture rates than those receiving RLX (incidence rate ratios (IRR) 0.45 [95% confidence interval (CI) 0.30 0.75, p = 0.001], 0.25 [95% CI 0.09 0.65, p = 0.005], 0.71 [95% CI 0.56 0.91, p = 0.006], 0.47 [95% CI 0.30 0.75, p = 0.0012], respectively). The cholesterol-lowering effect was stronger in the RLX group than in the MIN group, regardless of prior statin use. These results indicated that MIN treatment was more effective in reducing fracture risk in patients with higher LDL cholesterol levels, although its cholesterol-lowering ability was lesser than the RLX treatment.Trial registration University Hospital Medical Information Network-Clinical Trials Registry (UMIN-CTR), No. UMIN000005433; date: April 13, 2011.

Synthesis and preliminary anticancer evaluation of photo-responsive prodrugs of hydroxymethylene bisphosphonate alendronate

The antitumoral activity of hydroxymethylene bisphosphonates (HMBP) such as alendronate or zoledronate is hampered by their exceptional bone-binding properties and their short plasmatic half-life which preclude their accumulation in non-skeletal tumors. In this context, the use of lipophilic prodrugs represents a simple and straightforward strategy to enhance the biodistribution of bisphosphonates in these tissues. We describe in this article the synthesis of light-responsive prodrugs of HMBP alendronate. These prodrugs include lipophilic photo-removable nitroveratryl groups which partially mask the highly polar alendronate HMBP scaffold. Photo-responsive prodrugs of alendronate are stable in physiological conditions and display reduced toxicity compared to alendronate against MDA-MB-231 cancer cells. However, the antiproliferative effect of these prodrugs is efficiently restored after cleavage of their nitroveratryl groups upon exposure to UV light. In addition, substitution of alendronate with such photo-responsive substituents drastically reduces its bone-binding properties, thereby potentially improving its biodistribution in soft tissues after i.v. administration. The development of such lipophilic photo-responsive prodrugs is a promising approach to fully exploit the anticancer effect of HMBPs on non-skeletal tumors.