Are bisphosphonates the suitable anticancer drugs for the elderly?

Effects of zoledronic acid and geranylgeraniol on the cellular behaviour and gene expression of primary human alveolar osteoblasts

INTRODUCTION

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a serious complication of bisphosphonate therapy. The mechanism underlying BRONJ pathogenesis is poorly understood.

OBJECTIVES

To determine the effects of zoledronic acid (ZA) and geranylgeraniol (GGOH) on the mevalonate pathway (MVP) in osteoblasts generated from the human mandibular alveolar bone in terms of cell viability/proliferation, migration, apoptosis and gene expression.

MATERIALS AND METHODS

Primary human osteoblasts (HOBs) isolated from the mandibular alveolar bone were phenotyped. HOBs were cultured with or without ZA and GGOH for up to 72 h. Cellular behaviour was examined using a CellTiter-Blue® viability assay, an Ibidi culture-insert migration assay, an Apo-ONE® Homogeneous Caspase-3/7 apoptosis assay and transmission electron microscopy (TEM). Quantitative real-time reverse transcriptase polymerase chain reaction (qRT²-PCR) was used to determine the simultaneous expression of 168 osteogenic and angiogenic genes modulated in the presence of ZA and GGOH.

RESULTS

ZA decreased cell viability and migration and induced apoptosis in HOBs. TEM revealed signs of apoptosis in ZA-treated HOBs. However, the co-addition of GGOH ameliorated the effect of ZA and partially restored the cells to the control state. Twenty-eight genes in the osteogenic array and 27 genes in the angiogenic array were significantly regulated in the presence of ZA compared with those in the controls at one or more time points.

CONCLUSION

The cytotoxic effect of ZA on HOBs and its reversal by the addition of GGOH suggests that the effect of ZA on HOBs is mediated via the MVP.

CLINICAL RELEVANCE

The results suggest that GGOH could be used as a possible therapeutic/preventive strategy for BRONJ.

The effects of bisphosphonate on the remodeling of different irregular bones in mice

BACKGROUND

We aimed to compare the effects of bisphosphonate on the remodeling of irregular bones (the jaw and ilium) in mice after trauma.

METHODS

To verify the feasibility of modeling osteonecrosis, 20 mice were injected intraperitoneally with zoledronate and dexamethasone (ZOL&DEX group), dexamethasone (DEX group), or phosphate-buffered saline (PBS) [control (CTR) group]. Mice then underwent extraction of the right maxillary first molar and creation of an artificial bony cavity in the ilium. Bone sections were stained with H&E for morphological studies. To further compare differences between the maxilla and the ilium caused by similar traumas, 80 mice were injected intraperitoneally with ZOL&DEX or PBS. Pathological progression at the injury sites was assessed at 1 day and at 1, 3, and 8 weeks after trauma using micro-computed tomography (CT), H&E and immunohistochemistry analyses, high-performance liquid chromatography-mass spectrometry, and enzyme-linked immunosorbent assay.

RESULTS

Only the ZOL&DEX model group effectively developed osteonecrosis. Bony sequestra, osseous sclerosis, unhealed mucosa, and radiopaque alveolar bone were found in the maxilla. In the ilium, there was a lower frequency of osteonecrotic disease and osseous sclerosis, and less suppression of bone remodeling than in the maxilla following long-term bisphosphonate administration. Zoledronate levels were higher in the maxilla. ZOL&DEX treatment suppressed the levels of RANKL and IL-17, but induced an upregulation of osteoprotegerin and FAM20C in both bones.

CONCLUSION

Accumulation of bisphosphonate may increase the incidence of osteonecrosis. The RANKL/OPG pathway and IL-17 and FAM20C cytokines play key roles in the progression of pathologically abnormal bone remodeling.

Bone-targeted therapies for elderly patients with renal cell carcinoma: current and future directions

Bone metastases are very common in advanced renal cell carcinoma (RCC) and can have a huge impact on quality of life by leading to skeletal-related events (SREs), including pain, pathologic fractures and spinal cord compression with need for surgery or radiotherapy. Because of their osteolytic aspect and biologic behaviour, these SREs are more common in patients with bone metastases from RCC than from other malignancies. As overall survival is increased by new anti-angiogenic drugs like tyrosine kinase inhibitors and mammalian target of rapamycin inhibitors, the incidence of SREs is rising, making the clinical management of bone metastases in RCC ever more important, especially in the more vulnerable elderly patient. In this review we discuss the current advances and future directions in bone-targeted therapies in patients with RCC with a special focus on the elderly population. Recently, two bone-targeted agents have been approved in the prevention of SREs in advanced RCC: zoledronic acid and denosumab. To date, there is no specific data on the use of bisphosphonates or denosumab in the elderly and specific studies in this setting are warranted. We compare the available evidence for the use and implications of both agents in the elderly patient and give general information on safety concerns that could be more important in these patients.

Exposure to bisphosphonates and risk of cancer: a protocol for nested case-control studies using the QResearch primary care database

Introduction Bisphosphonates are becoming a common treatment for osteoporosis particularly after discovery of the association between hormone replacement therapy and increased risk of breast cancer. As osteoporosis develops with age, treatment is a long-term intervention. Randomised control trials typically have limited follow-up times, which restricts investigation of the effects of the drugs on risk of primary cancers. A few observational studies have demonstrated a reduced risk of breast cancer and possibly of endometrial cancer in bisphosphonate users. Two epidemiological studies have studied the effect of the drugs on oesophageal cancer but did not reach any definite conclusions. So far, no effects on colorectal and stomach cancer have been shown. This study will investigate the association of bisphosphonates with risks of the 10 most common primary cancers. Methods and analysis A series of nested case-control studies will be based on the general population using records from 660 UK general practices within the QResearch Database. Cases will be patients with primary cancers diagnosed between 1996 and 2011. Each case will be matched by age, sex, practice and calendar year to five controls, who are alive and registered with the practice at the time of diagnosis of the case. Exposure to bisphosphonates will be defined as at least one prescription during the study period. For the most common cancers with substantial numbers of observations, the effect of the duration of the treatment and different types of bisphosphonates will be studied. Conditional logistic regression will be applied to produce ORs adjusted for smoking status, socioeconomic status, ethnicity, cancer-specific co-morbidities and use of other medications.

Could targeting bone delay cancer progression? Potential mechanisms of action of bisphosphonates

Although dissemination may occur early in the course of many cancers, the development of overt metastases depends upon a variety of factors inherent to the cancer cells and the tissue(s) they colonize. The time lag between initial dissemination and established metastases could be several years, during which period the bone marrow may provide an unwitting sanctuary for disseminated tumor cells (DTCs). Survival in a dormant state within the bone marrow may help DTCs weather the effects of anticancer therapies and seed posttreatment relapses. The importance of the bone marrow for facilitating DTC survival may vary depending on the type of cancer and mechanisms of tumor cell dissemination. By altering the bone microenvironment, bisphosphonates may reduce DTC viability. Moreover, some bisphosphonates have demonstrated multiple anticancer activities. These multiple mechanisms may help explain the improvement in disease outcomes with the use of zoledronic acid in malignancies like breast cancer and multiple myeloma.

Challenges in clinical patient management

The use of endocrine therapy in breast cancer represents one of the earliest molecular targeting strategies used in cancer treatment. Tamoxifen, a selective estrogen-receptor (ER) modulator, has been the standard of care for women with receptor-positive breast cancer for the last 30 years. Tamoxifen suppresses the estrogen-dependent growth of breast cancer cells by specifically targeting the ER. Because of estrogenic effects, tamoxifen does not increase the risk of osteoporosis, but it can lead to endometrial cancer and thromboembolism. The third-generation aromatase inhibitors (AIs) exert their tumor antiproliferative action by targeting an enzyme critical for estrogen biosynthesis. The AIs thus have a different mechanism of action than tamoxifen, and a different safety profile. The majority of adverse events (AEs) related to the AIs are mild to moderate. Most of these AEs are common to menopause and are predictable and manageable. This review looks at AI-associated side effects and current clinical management strategies, with a particular emphasis on managing bone health. Compliance with long-term therapy, strategies to improve adherence, and considerations in elderly patients with hormone-responsive breast cancer are also discussed.

Bisphosphonate-induced osteonecrosis of the jaw: a medical enigma?

Bisphosphonates are used for the standard of care of patients with skeletal metastases and hypocalcemia of malignancy. Bisphosphonate-induced osteonecrosis (BION) is a serious complication. Clinically, BION presents as an area of exposed alveolar bone that occurs spontaneously or becomes evident following an invasive surgical procedure such as extraction of a tooth, periodontal surgery, apicoectomy, or oral implant placement. The mechanism by which bisphosphonates cause osteonecrosis is uncertain. There are no controlled trials to show a direct cause-effect relationship between bisphosphonates and osteonecrosis of the jaw. Oral bisphosphonate-induced necrosis is a rare clinical entity, less frequent, less aggressive, more predictable, and more responsive to treatment than IV forms of bisphosphonate-related osteonecrosis of the jaw. However, there have been reports of this complication with the less potent oral forms of bisphosphonates (0.007% to 0.01%). The morbidity of osteonecrosis of the jaw induced by IV bisphosphonates is significant, so prevention should receive prime importance. Patients should receive prophylactic dental examinations, and any necessary dental treatment before starting bisphosphonate therapy. Good communication among dentists, oral surgeons, physicians, and oncologists is of vital importance in providing care of these patients.