The role of bisphosphonates in multiple myeloma: mechanisms, side effects, and the future

The assessment of halitosis with a new screening tool in medication-related osteonecrosis of the jaw

OBJECTIVES

This study aimed to identify the levels of halitosis in patients with Medication-related osteonecrosis of the jaw (MRONJ) and osteoporosis and to suggest a new MRONJ screening method using halitosis measurement.

MATERIALS AND METHODS

From October 2019 to April 2023, participants aged 19 years or older without periodontal disease were selected. Seventy-five participants, 25 in each group, were divided into an MRONJ group, an osteoporosis group without MRONJ, and a control group without osteoporosis and not taking osteoporosis drugs or antibiotics. Each participant underwent halitosis assessment twice using an exhaled breath analyzer to measure halitosis twice by blowing a straw for 1 min. Measured concentrations of hydrogen, hydrogen sulfide, and methyl mercaptan were compared between groups.

RESULTS

Data from 22 patients in the MRONJ group, 25 in the osteoporosis group, and 25 in the control group were analyzed. The concentrations of hydrogen sulfide and methyl mercaptan were significantly higher in the MRONJ group than in the other groups, but the concentrations of hydrogen did not differ between the groups. When comparing the concentrations of hydrogen sulfide and methyl mercaptan in osteoporosis patients and solid cancer patients in the MRONJ group, there was a significant difference in hydrogen sulfide concentration, but there was no significant difference in methyl mercaptan.

CONCLUSIONS

Quantifying the level of halitosis can be used to screen for MRONJ in patients taking bisphosphonates, such as patients with osteoporosis, prostate cancer, and breast cancer.

CLINICAL RELEVANCE

MRONJ is accompanied by bad breath, and the concentrations of hydrogen sulfide and methyl mercaptan are associated with MRONJ.

Medication-related osteonecrosis of the jaw using periodontitis-induced rat before tooth extraction

OBJECTIVE

This study aimed to investigate the occurrence of medication-related osteonecrosis of the jaw (MRONJ) after tooth extraction due to periodontitis in ovariectomized rats.

METHODS

Twenty-four osteoporosis-induced rats were administered with zoledronic acid (ZA; ZA group) or saline (CONT group). In both groups, tooth extraction was performed after inducing periodontitis, and all animals were sacrificed 8-week after tooth extraction.

RESULTS

Micro-CT of the tibia showed that the bone volume fraction, bone surface density, trabecular number, and bone mineral density were significantly higher in the ZA group than in the CONT group. Histologically, the proliferative zone on the growth plate was thicker in the ZA group than in the CONT group. Micro-CT of the extraction sites revealed that the bone volume fraction was significantly higher in the ZA group than in the CONT group. Radiologically, the ZA group showed partial healing and delayed healing. Histological analysis revealed normal bone healing status with completely healed epithelium in the extraction sites of the CONT group, whereas abnormal empty osteocytes in the necrotic bone and inflammatory infiltration were observed in the ZA group.

CONCLUSION

The incidence of MRONJ increased in the rats administered with ZA.

Increased Bone Volume by Ixazomib in Multiple Myeloma: 3-Month Results from an Open Label Phase 2 Study

Multiple myeloma (MM) is an incurable bone marrow cancer characterized by the development of osteolytic lesions due to the myeloma-induced increase in osteoclastogenesis and decrease in osteoblastic activity. The standard treatment of MM often involves proteasome inhibitors (PIs), which can also have a beneficial off-target bone anabolic effect. However, long-term treatment with PIs is unadvised due to their high side-effect burden and inconvenient route of administration. Ixazomib is a new-generation, oral PI that is generally well tolerated; however, its bone effect remains unknown. Here, we describe the 3-month results of a single-center phase II clinical trial investigating the effect of ixazomib treatment on bone formation and bone microstructure. Thirty patients with MM in stable disease not receiving antimyeloma treatment for ≥3 months and presenting ≥2 osteolytic lesions received monthly ixazomib treatment cycles. Serum and plasma samples were collected at baseline and monthly thereafter. Sodium ¹⁸ F-Fluoride positron emission tomography (NaF-PET) whole-body scans and trephine iliac crest bone biopsies were collected before and after three treatment cycles. The serum levels of bone remodeling biomarkers suggested an early ixazomib-induced decrease in bone resorption. NaF-PET scans indicated unchanged bone formation ratios; however, histological analyses of bone biopsies revealed a significant increase in bone volume per total volume after treatment. Further analyses of bone biopsies showed unchanged osteoclast number and COLL1A1^High -expressing osteoblasts on bone surfaces. Next, we analyzed the superficial bone structural units (BSUs), which represent each recent microscopic bone remodeling event. Osteopontin staining revealed that following treatment, significantly more BSUs were enlarged (>200,000 μm² ), and the distribution frequency of their shape was significantly different from baseline. Overall, our data suggest that ixazomib induces overflow remodeling-based bone formation by decreasing the level of bone resorption and promoting longer bone formation events, making it a potentially valuable candidate for future maintenance treatment. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Chitosan modified with lanthanum ions as implantable hydrogel for local delivery of bisphosphonates

Osteoporosis is a disease that affects many people around the world. One group of drugs used to treat it are bisphosphonates. However, they have poor bioavailability and many side effects. Therefore, research around the world is focused on developing bisphosphonate delivery systems. In this paper, we would like to present the design of a hydrogel material with chitosan matrix modified with lanthanum, that could serve as an implantable hydrogel capable of sustained and slow release of Zoledronate. Various research techniques were used to characterize the materials, and the swelling ratio and water solubility were also tested. The conducted research proved that the prepared hydrogel is capable of the long-term release of the Zoledronate. Thanks to this, the prepared material can be successfully used as an implantable hydrogel or a coating on titanium implants for the local delivery of drugs.

Monoclonal Gammopathies and the Bone Marrow Microenvironment: From Bench to Bedside and Then Back Again

Multiple myeloma (MM) is an incurable hematologic malignancy characterized by a multistep evolutionary pathway, with an initial phase called monoclonal gammopathy of undetermined significance (MGUS), potentially evolving into the symptomatic disease, often preceded by an intermediate phase called "smoldering" MM (sMM). From a biological point of view, genomic alterations (translocations/deletions/mutations) are already present at the MGUS phase, thus rendering their role in disease evolution questionable. On the other hand, we currently know that changes in the bone marrow microenvironment (TME) could play a key role in MM evolution through a progressive shift towards a pro-inflammatory and immunosuppressive shape, which may drive cancer progression as well as clonal plasma cells migration, proliferation, survival, and drug resistance. Along this line, the major advancement in MM patients' survival has been achieved by the introduction of microenvironment-oriented drugs (including immunomodulatory drugs and monoclonal antibodies). In this review, we summarized the role of the different components of the TME in MM evolution from MGUS as well as potential novel therapeutic targets/opportunities.

The prognostic value and therapeutic targeting of myeloid-derived suppressor cells in hematological cancers

The success of immunotherapeutic approaches in hematological cancers is partially hampered by the presence of an immunosuppressive microenvironment. Myeloid-derived suppressor cells (MDSC) are key components of this suppressive environment and are frequently associated with tumor cell survival and drug resistance. Based on their morphology and phenotype, MDSC are commonly subdivided into polymorphonuclear MDSC (PMN-MDSC or G-MDSC) and monocytic MDSC (M-MDSC), both characterized by their immunosuppressive function. The phenotype, function and prognostic value of MDSC in hematological cancers has been intensively studied; however, the therapeutic targeting of this cell population remains challenging and needs further investigation. In this review, we will summarize the prognostic value of MDSC and the different attempts to target MDSC (or subtypes of MDSC) in hematological cancers. We will discuss the benefits, challenges and opportunities of using MDSC-targeting approaches, aiming to enhance anti-tumor immune responses of currently used cellular and non-cellular immunotherapies.

Case Report - Short-term Bisphosphonate Use Associated Stress Fractures

Introduction

Long-term bisphosphonate use has been linked to an increased risk of pathological neck of femur fractures.

Case Report

We write concerning a patient who presented with the left hip pain following a low impact fall, which was diagnosed as a pathological left neck of femur fracture. This was a subtrochanteric stress fracture most frequently seen in patients who take bisphosphonate medications. A key point of difference in our patient is the length of time of bisphosphonate use. A further interesting point was the method of imaging used to diagnose this fracture whereby plain radiographs and computerized tomography imaging both did not show any acute fracture whereas only a magnetic resonance imaging (MRI) hip demonstrated this fracture. Surgical insertion of a prophylactic intramedullary nail was done to stabilize the fracture and reduce the risk of progression to a complete fracture.

Conclusion

This case brings up multiple key points not reviewed previously such as the fact a fracture developed only 1 month after bisphosphonate use rather than months or years. These points suggest that there should be a low threshold for investigation (including MRI scanning) into potential pathological fractures and that bisphosphonate use should be a red flag to initiate these investigations regardless of length of use.

Modulating Macrophage Clearance of Nanoparticles: Comparison of Small-Molecule and Biologic Drugs as Pharmacokinetic Modifiers of Soft Nanomaterials

Nanomedicines show benefits in overcoming the limitations of conventional drug delivery systems by reducing side effects, toxicity, and exhibiting enhanced pharmacokinetic (PK) profiles to improve the therapeutic window of small-molecule drugs. However, upon administration, many nanoparticles (NPs) prompt induction of host innate immune responses, which in combination with other clearance pathways such as renal and hepatic, eliminate up to 99% of the administered dose. Here, we explore a drug predosing strategy to transiently suppress the mononuclear phagocyte system (MPS), subsequently improving the PK profile and biological behaviors exhibited by a model NP system [hyperbranched polymers (HBPs)] in an immunocompetent mouse model. In vitro assays allowed the identification of five drug candidates that attenuated cellular association. Predosing of lead compounds chloroquine (CQ) and zoledronic acid (ZA) further showed increased HBP retention within the circulatory system of mice, as shown by both fluorescence imaging and positron emission tomography-computed tomography. Flow cytometric evaluation of spleen and liver tissue cells following intravenous administration further demonstrated that CQ and ZA significantly reduced HBP association with myeloid cells by 23 and 16%, respectively. The results of this study support the use of CQ to pharmacologically suppress the MPS to improve NP PKs.

Vγ9Vδ2 T cells expressing a BCMA—Specific chimeric antigen receptor inhibit multiple myeloma xenograft growth

Vγ9Vδ2 T cells are immune effector cells capable of killing multiple myeloma (MM) cells and have been tested in clinical trials to treat MM patients. To enhance the MM cell killing function of Vγ9Vδ2 T cells, we introduced a BCMA-specific CAR into ex vivo expanded Vγ9Vδ2 T cells through electroporation of the CAR-encoding mRNA. The modified Vγ9Vδ2 T cells displayed a high cytolytic activity against BCMA-expressing MM cell lines in vitro, while sparing BCMA-negative cells, including normal B cells and monocytes. Subsequently, we intravenously injected KMS-11 human MM cells to generate a xenograft mouse model. The treatment of the tumor-bearing mice with Zometa and anti-BCMA CAR- Vγ9Vδ2 T cells resulted in a significant reduction of tumor burden in the femur region, as well as the overall tumor burden. In association with the decrease in tumor burden, the survival of the MM cell-inoculated mice was markedly prolonged. Considering the potential of Vγ9Vδ2 T cells to be used as off-the-shelf products, the modification of these cells with a BCMA-specific CAR could be an attractive option for cancer immunotherapy against bone marrow cancer MM.

Zoledronic acid-induced oxidative damage and endoplasmic reticulum stress-mediated apoptosis in human embryonic kidney (HEK-293) cells

Zoledronic acid, a nitrogen-containing bisphosphonate drug, is used for the treatment of osteoporosis, Paget's disease of bone, and tumor-induced osteolysis. Zoledronic acid has also gained a place in cancer treatment due to its cytotoxic and antiproliferative effects in many cancer cells. Although zoledronic acid is considered safe, kidney damage is still one of the concerns in therapeutic doses. In the study, the aim was to assess the nephrotoxic profiles of zoledronic acid in the human embryonic kidney (HEK-293) cells. Cytotoxicity evaluation was performed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) and neutral red uptake tests, while oxidative stress was performed by reactive oxygen species (ROS) production via flow cytometry, and the incomprehensible evaluation of ROS-related genes by RT-PCR and apoptosis was performed with Annexin-PI analysis in flow cytometry. The obtained result showed that zoledronic acid inhibited cell viability (IC₅₀ values were determined as 273.16  by MTT) and cell proliferation in a concentration-dependent manner, induced ROS production, caused glutathione depletion, and increased oxidative stress index and endoplasmic reticulum (ER) stress, indicating severe cellular stress. The expression levels of oxidative damage (L-fabp, α-GST, Nrf2, and HMOX1), ER stress (CASP4, IRE1-α, GADD153, and GRP78), and apoptosis (Bcl-2, Bax, Cyt-c, p53, CASP9, CASP3, NF-κB, TNF-α, and JNK) related genes were altered as well as IRE1-α protein levels. Herein, we were the first to show that increased oxidative stress and ER stress resulting in apoptosis are the key molecular pathways in zoledronic acid-induced nephrotoxicity equivalent to clinically administered concentrations.

Qualitative focus group interview study of communication between patients, dentists and physicians for efficient osteonecrosis of the jaw practices

OBJECTIVES

To investigate problems and the current status of existing methods of communication between patients, dentists and physicians for the prevention and treatment of medication-related osteonecrosis of the jaw (MRONJ).

DESIGN

A focus group interview study with a descriptive design using qualitative content analysis of transcripts.

SETTING

Secondary care in Korea.

PARTICIPANTS

3 patient groups and 4 health professional groups in a total of 32 participants including patients with osteoporosis or bone metastasis, dentists and physicians.

RESULTS

This study revealed that patients lacked medical knowledge of osteoporosis drugs, whereas dentists and physicians lacked each other's expertise. All patients reported undergoing dental treatments during the osteoporosis drug treatment, but dentists and physicians had different MRONJ experiences depending on their work setting in primary or secondary care. Patients expressed dissatisfaction with the current system of communication with health professionals via letter as they found this to be a slow process. Dentists and physicians reported the need for effective communication because they felt defensive when sending and receiving medical consults.

CONCLUSIONS

Despite the low incidence of MRONJ among patients with osteoporosis, it is difficult to treat; thus, it is necessary to inform dentists, physicians and patients about the importance of MRONJ prevention. To this end, close communication among all involved stakeholders about osteoporosis drugs is required.

Pathogenesis and Treatment of Myeloma-Related Bone Disease

Multiple myeloma is a hematologic malignancy of plasma cells that causes bone-destructive lesions and associated skeletal-related events (SREs). The pathogenesis of myeloma-related bone disease (MBD) is the imbalance of the bone-remodeling process, which results from osteoclast activation, osteoblast suppression, and the immunosuppressed bone marrow microenvironment. Many important signaling cascades, including the RANKL/RANK/OPG axis, Notch signaling, the Wnt/β-Catenin signaling pathways, and signaling molecules, such as DKK-1, sclerostin, osteopontin, activin A, chemokines, and interleukins are involved and play critical roles in MBD. Currently, bisphosphonate and denosumab are the gold standard for MBD prevention and treatment. As the molecular mechanisms of MBD become increasingly well understood, novel agents are being thoroughly explored in both preclinical and clinical settings. Herein, we will provide an updated overview of the pathogenesis of MBD, summarize the clinical management and guidelines, and discuss novel bone-modifying therapies for further management of MBD.

Medication-related osteonecrosis of the jaw: An update

Antiresorptive medications, such as bisphosphonates and denosumab, are an important class of medication used to treat a wide range of diseases from osteoporosis to multiple myeloma. Unfortunately, they are also associated with a rare but devastating side effect – medication-related osteonecrosis of the jaw (MRONJ). First reported in 2003, much research has been done into the area; however, the exact pathophysiology continues to elude clinicians and researchers. What has been ascertained is that intravenous treatment, duration of treatment, and tooth extraction are major risk factors. Staging and treatment guidelines have been proposed; however, there has been no universal acceptance, and clinicians rely on various position papers. Over the next 30 years, the aging population is set to double, and with it, the prescription of antiresorptive medication and incidence of MRONJ will undoubtedly increase. In 2013, Gupta et al. published a paper on bisphosphonate-related osteonecrosis of the jaw; however, there have many changes since then. This paper aims to provide a succinct update on those changes.

Initial Therapeutic Approaches to Patients with Multiple Myeloma

Multiple Myeloma (MM) is part of a spectrum of plasma cell disorders that may result in end organ damage. MM is subclassified into high and standard risk based on cytogenetic and laboratory markers. The treatment of newly diagnosed multiple myeloma is constantly changing with the advent of novel therapies. Recent advances in therapies have resulted in longer time to remission and overall survival. the introduction of targeted therapy with monoclonal antibodies such as Daratumumab has improved stringent complete response to 39%. In this review, we outline the current approach to diagnosis, prognosis, and management of newly diagnosed multiple myeloma in both transplant eligible and ineligible patients.

Bisphosphonates, Old Friends of Bones and New Trends in Clinics

Bisphosphonates, used for a long time in osteoporosis management, are currently the target of intensive research, from pre-formulation studies to more advanced stages of clinical practice. This review presents an overview of the contributions of this family of compounds to human health, starting with the chemistry and clinical uses of bisphosphonates. Following this, their pharmacology is described, highlighting administration-borne handicaps and undesirable effects. The last three sections of the review describe the research efforts that seek to curb delivery-related issues and expand bisphosphonate use. Innovative routes and strategies of administration, such as nano-encapsulation for oral intake or injectable cements for local or in-bone delivery are presented, as well as the latest results of case studies or preclinical studies proposing new therapeutic indications for the clinically approved bisphosphonates. Finally, a selection of anti-infectious bisphosphonate new drug candidates is shown, with focus on the molecules reported in the last two decades.

The Importance of Alliance between Hematologists and Dentists: A Retrospective Study on the Development of Bisphosphonates Osteonecrosis of the Jaws (Bronj) in Multiple Myeloma Patients

(1) Background: Multiple myeloma is a rare cancer that primarily affects the bone marrow. Osteoclasts are responsible for increased bone resorption and, therefore, bone destruction. Bisphosphonates are a class of drugs that can slow down bone resorption by reducing the number and action of osteoclasts. Intravenous injections of bisphosphonates (generally Zoledronic Acid) are administered to patients affected by Multiple Myeloma, but BRONJ is described as a serious side effect. This 5-year retrospective study aims to evaluate the efficacy of appropriate dental treatment protocols prior to initiating bisphosphonate therapy to prevent the development of BRONJ. (2) Methods: A total of 99 patients with symptomatic multiple myeloma were involved in this study (41-90 years, mean age 65 years, standard deviation 5 years). The data relating to the visits were tracked using a specific server and consulting the clinical reports. The AAOMS (American Association of Oral and Maxillofacial Surgeons) position was applied for both diagnosis and treatment. A total of 79 patients were examined before the administration of bisphosphonates (group A) and 20 after (group B). (3) Results: The entire sample required dental treatment: 23.2% underwent restorative therapy, 8% endodontic treatments, 44.4% tooth extractions. Periodontal disease was present in 41.4% of the patients. No osteonecrosis was observed in the first group, whereas BRONJ was found in five patients of the second one (25%) and two patients (10%) showed osteosclerotic areas under investigation [OR 0.026 (CI 0.0027 to 0.2454)]. (4) Conclusions: In the literature, there are no precise data about the prevalence of BRONJ. Despite the limitation of the present study, we point out that dental treatment before the treatment with intravenous bisphosphonates can help in reducing the incidence of BRONJ and good dental status is necessary for BRONJ prevention.

Recent Advances in Nanotherapeutics for Multiple Myeloma

Simple Summary

Nanotherapeutics are useful tools to improve the deliverability of drugs, especially anti-cancer drugs that need to target specific cells. Several approaches have been studied for multiple myeloma, considering that immune cells are not easy to target with the available drugs. These pharmacological agents are administered in various combinations using Thalidomide (or Lenalidomide, Pomalidomide), corticosteroids (Dexamethasone), proteasome inhibitors (Bortezomib, Carfilzomib, Ixazomib), deacetylase inhibitors (Panobinostat), and monoclonal antibodies (Elotuzumab, Daratumumab). As all drugs these agents might have serious side effects and in addition, the reliance on stochastic events to deliver drugs to tumors reduces their effectiveness either through rapid clearance from blood or inadequate concentration in cancer cells. To address these issues liposomes, micelles, polymeric nanoparticles, inorganic nanoparticles, and carbon-based nanomaterials have been successfully tested in vivo and can be considered as useful tools to improve delivery of active pharmaceuticals that show poor bioavailability or poor internalization into myeloma cells.

Abstract

Anticancer therapies cannot be included in a one-size-fits-all scenario; it is imperative to adapt therapies to the tumor molecular profile and most importantly to develop target-specific therapeutics. Nanotherapeutics can combine molecular imaging with molecular therapy in order to provide the maximum benefit to patients in terms of disease prevention, identification, and treatment. Nanotechnology applied to therapy provides numerous advantages in diagnostics and in drug delivery, especially for those malignant cells that are difficult to target or for drugs with poor bioavailability, such as those used for multiple myeloma (MM). This review summarizes the recent advances in the development of nanoparticle-based systems for the treatment of MM, taking into account the methods used for their functionalization, biocompatibility, and anticancer activity.

Paradoxical Stress Fracture in a Patient With Multiple Myeloma and Bisphosphonate Use

Multiple myeloma (MM) is a plasma cell disorder with related organ dysfunction, including hypercalcemia, renal insufficiency, anemia, and bone disease. Osteolytic bone lesions that result in pain and pathologic fractures are a major source of morbidity and the use of bisphosphonates is generally safe and effective treatment in reducing myeloma-related skeletal fractures and associated morbidity. We present a 73-year-old African American woman with MM in remission and on intravenous (IV) bisphosphonate therapy in the past five years who reported gradually worsening bilateral thigh pain of six months duration. A bone survey showed no neoplastic focus, and bilateral hip X-rays showed incomplete insufficiency stress fractures with characteristic features suspicious for bisphosphonate-related atypical femoral fracture (AFF). Increasingly reported in the literature, bilateral AFF is a unique and serious adverse effect for patients on bisphosphonates. Our case illustrates the distinct challenges in managing a patient with MM on long-term bisphosphonate therapy who suffered bilateral atypical femoral fractures, an uncommon presentation of a relatively rare phenomenon. It is important to balance the established benefits of bisphosphonate therapy with potential fracture risk and be particularly vigilant about adverse effect monitoring and timely intervention.

Acute Kidney Injury in Patients Receiving Systemic Treatment for Cancer: A Population-Based Cohort Study

BACKGROUND

Patients undergoing treatment for cancer are at increased risk of acute kidney injury (AKI). There are few data on AKI incidence and risk factors in the current era of cancer treatment.

METHODS

We conducted a population-based study of all patients initiating systemic therapy (chemotherapy or targeted agents) for a new cancer diagnosis in Ontario, Canada (2007-2014). The primary outcome was hospitalization with AKI or acute dialysis. We estimated the cumulative incidence of AKI and fitted Fine and Gray models, adjusting for demographics, cancer characteristics, comorbidities, and coprescriptions. We modeled exposure to systemic therapy (the 90-day period following treatments) as a time-varying covariate. We also assessed temporal trends in annual AKI incidence.

RESULTS

We identified 163 071 patients initiating systemic therapy of whom 10 880 experienced AKI. The rate of AKI was 27 per 1000 person-years, with overall cumulative incidence of 9.3% (95% CI = 9.1% to 9.6%). Malignancies with the highest 5-year AKI incidence were myeloma (26.0%, 95% CI = 24.4% to 27.7%), bladder (19.0%, 95% CI = 17.6% to 20.5%), and leukemia (15.4%, 95% CI = 14.3% to 16.5%). Advanced cancer stage, chronic kidney disease, and diabetes were associated with increased risk of AKI (adjusted hazard ratios [aHR] = 1.41, 95% CI = 1.28 to 1.54; 1.80, 95% CI = 1.67 to 1.93; and 1.43, 95% CI = 1.37 to 1.50, respectively). In patients aged 66 years or older with universal drug benefits, diuretic, and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker coprescription was associated with higher AKI risk (aHR = 1.20, 95% CI = 1.14 to 1.28; 1.30, 95% CI = 1.23 to 1.38). AKI risk was further accentuated during the 90-day period following systemic therapy (aHR = 2.34, 95% CI = 2.24 to 2.45). The annual incidence of AKI increased from 18 to 52 per 1000 person-years between 2007 and 2014.

CONCLUSION

Cancer-related AKI is common and associated with advanced stage, chronic kidney disease, diabetes, and concomitant receipt of diuretics or angiotensin-converting enzyme inhibitors/angiotensin receptor blockers. Risk is heightened in the 90 days after systemic therapy. Preventive strategies are needed to address the increasing burden of AKI in this population.

Therapeutic targets in myeloma bone disease

Multiple myeloma (MM) is the second most common haematological malignancy and is characterized by a clonal proliferation of neoplastic plasma cells within the bone marrow. MM is the most frequent cancer involving the skeleton, causing osteolytic lesions, bone pain and pathological fractures that dramatically decrease MM patients' quality of life and survival. MM bone disease (MBD) results from uncoupling of bone remodelling in which excessive bone resorption is not compensated by new bone formation, due to a persistent suppression of osteoblast activity. Current management of MBD includes antiresorptive agents, bisphosphonates and denosumab, that are only partially effective due to their inability to repair the existing lesions. Thus, research into agents that prevent bone destruction and more importantly repair existing lesions by inducing new bone formation is essential. This review discusses the mechanisms regulating the uncoupled bone remodelling in MM and summarizes current advances in the treatment of MBD. LINKED ARTICLES: This article is part of a themed issue on The molecular pharmacology of bone and cancer-related bone diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.9/issuetoc.

Use of bone-modifying agents and clinical outcomes in older adults with multiple myeloma

Background

Guidelines recommend bone‐modifying agents (BMAs) for all patients initiating treatment for myeloma. We examined adherence to this recommendation, and BMA effectiveness in the era of bortezomib/lenalidomide‐based therapy among Medicare beneficiaries.

Methods

From the linked Surveillance, Epidemiology, and End Results‐Medicare registry, we selected beneficiaries receiving anti‐myeloma chemotherapy in 2007‐2013. We matched BMA recipients (within 90 days of first chemotherapy) to nonrecipients using a propensity score, balancing patient‐, disease‐, and therapy‐related confounders. Cumulative incidence of skeletal‐related events (SREs) and overall survival (OS) was compared in proportional hazard models accounting for competing risks and immortal‐time bias.

Results

Among 4611 patients with median age of 76 years, 51% received BMA. Bone‐modifying agents use remained steady over time (P = .87) and was significantly less frequent for patients who were older, with comorbidities, without prior SRE, and those treated without bortezomib or lenalidomide. In a propensity score‐matched cohort, BMA recipients experienced a lower incidence of SRE (11.0% vs 14.6% at 3 years; subhazard ratio, 0.73; 95% CI, 0.60‐0.89) and better OS (53.3% vs 47.8% at 3 years; hazard ratio, 0.86; 95% CI, 0.77‐0.95). The results were consistent in the subgroup (76%) treated with bortezomib and/or immunomodulatory drugs (IMiDs). The incidence of osteonecrosis of the jaw (ONJ) was 3.2% at 3 years.

Conclusions

In this observational study, the observed benefits of early BMA administration among patients treated with contemporary anti‐myeloma regimens were similar to historical clinical trials. Frequent omission of BMA highlights a remediable deficiency in the quality of supportive care, and suggests that timely administration may be a useful indicator of quality care in myeloma.

Novel insights into the complex architecture of osteoporosis molecular genetics

Osteoporosis is a prevalent osteodegenerative disease and silent killer linked to a decrease in bone mass and decline of bone microarchitecture, due to impaired bone matrix mineralization, raising the risk of fracture. Nevertheless, the process of bone matrix mineralization is still an unsolved mystery. Osteoporosis is a polygenic disorder associated with genetic and environmental risk factors; however, the majority of genes associated with osteoporosis remain largely unknown. Several signaling pathways regulate bone mass; therefore, dysregulation of a single signaling pathway leads to metabolic bone disease owing to high or low bone mass. Parathyroid hormone, core-binding factor α-1 (Cbfa1), Wnt/β-catenin, the receptor activator of the nuclear factor kappa-B (NF-κB) ligand (RANKL), myostatin, and osteogenic exercise signaling pathways play pivotal roles in the regulation of bone mass. The myostatin signaling pathway increases bone resorption by activating the RANKL signaling pathway, whereas osteogenic exercise inhibits myostatin and sclerostin while inducing irisin that consequentially activates the Cbfa1 and Wnt/β-catenin bone formation pathways. The aims of this review are to summarize what is known about osteoporosis-related signaling pathways; define the role of these pathways in osteoporosis drug discovery; focus light on the link between bone, muscle, pancreas, and adipose integrative physiology and osteoporosis; and underline the emerging role of osteogenic exercise in the prevention of, and care for, osteoporosis, obesity, and diabetes.

Multiple Myeloma and Bone: The Fatal Interaction

Multiple myeloma (MM) is the second-most-common hematologic malignancy and the most frequent cancer to involve bone. MM bone disease (MMBD) has devastating consequences for patients, including dramatic bone loss, severe bone pain, and pathological fractures that markedly decrease the quality of life and impact survival of MM patients. MMBD results from excessive osteoclastic bone resorption and persistent suppressed osteoblastic bone formation, causing lytic lesions that do not heal, even when patients are in complete and prolonged remission. This review discusses the cellular and molecular mechanisms that regulate the uncoupling of bone remodeling in MM, the effects of MMBD on tumor growth, and potential therapeutic approaches that may prevent severe bone loss and repair damaged bone in MM patients.

Would Be Prophylactic Administrations of Low Concentration of Alendronate an Alternative for Improving the Craniofacial Bone Repair? A Preliminary Study Focused in the Period of Cellular Differentiation and Tissue Organization

BACKGROUND

Alendronate (ALN) is a nitrogen-bisphosphonate that may induce an anabolic effect on craniofacial bone repair when administrated in low doses. Based on this premise, this study analyzed the influence of prophylactic low doses of ALN on bone healing in defects created in rabbit mandible.

METHODS

A 5 × 2-mm diameter deep defect was created in the calvaria of 28 rabbits. Fourteen of these rabbits received previously 50 μg/kg of 1% sodium ALN for 4 weeks, while the other rabbits received only 0.9% physiological saline solution (control). Animals were euthanized at 15 and 60 days postsurgery (n = 7), and the data were analyzed using histomorphometry and immunohistochemistry using the anti-CD34, bone morphogenetic protein -2 (BMP-2), and transforming growth factor (TGF)-β1 antibodies.

RESULTS

On the 15th day postsurgery, the specimens that received previous treatment with ALN demonstrated large vascular lumen and intense positivity to CD34 either concentrated in endothelium or cells spread among the reparative tissue. These results coincided with intense positivity for BMP-2+ cells and TGF-β1 that was concentrated in both cells and perivascular area. In contrast, the control group revealed scarce cells that exhibited CD34, BMP-2+, and the TGF-β1 was restricted for perivascular area on well-formed granulation tissue. These patterns of immunohistochemical result, especially found on the 15th day of analysis, seem to be responsible for the development of larger quantities of bone matrix in the specimens that receive ALN on the 60th day postsurgery.

CONCLUSION

These preliminary results showed that the prophylactic administration of low doses of ALN might be an alternative to craniofacial bone craniofacial bone repair because it increases the immunopositivity for TGF-β1 and consequently improves the CD34+ and BMP-2+ cells on reparative sites.

Mesenchymal stem cells expressing osteoprotegerin variants inhibit osteolysis in a murine model of multiple myeloma

The current treatment options for multiple myeloma (MM) osteolytic lesions are mainly combinations of chemotherapy and other small-molecule inhibitors, but toxic side effects still remain a major concern. Studies have shown that osteoclast activity is enhanced in MM patients through increased expression of receptor activator of nuclear factor κB ligand (RANKL), triggering RANK signaling on osteoclast precursors, which results in aggressive bone resorption. Furthermore, osteoprotegerin (OPG), a decoy receptor for RANKL, and the osteogenic potential of mesenchymal stem cells (MSCs) are significantly decreased in myeloma patients with multiple bone lesions. Thus, the use of OPG as a therapeutic molecule would greatly decrease osteolytic damage and reduce morbidity. However, in addition to inhibiting osteoclast activation, OPG binds to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), thereby rendering the tumor cells resistant to TRAIL-induced apoptosis and limiting the use of OPG for therapy. The present study developed a bone-disseminated myeloma disease model in mouse and successfully tested a cell therapy approach using MSCs, genetically engineered to express OPG variants that retain the capacity to bind RANKL, but do not bind TRAIL. Our results of skeletal remodeling following this regenerative stem cell therapy with OPG variants indicated a significant protection against myeloma-induced osteolytic bone damage in areas of major myeloma skeletal dissemination, suggesting the potential of this therapy for treating osteolytic damage in myeloma patients.

Intravenous bisphosphonate therapy does not thicken cementum or change periodontal ligaments of cancer patients

OBJECTIVE

To test the hypothesis that intravenous (IV) bisphosphonate (BP) therapy thickens or alters the micromorphology of cementum and periodontal ligament (PDL) in cancer patients.

STUDY DESIGN

Thirty-two teeth extracted from 24 cancer patients and separated into test (patients who have undergone IV BP therapy, n = 16) and control (patients naive to BP therapy, n = 16) groups were studied. Cementum thickness was measured in 3 different areas of the dental root with polarized light microscopy. PDL was assessed by optical light microscopy and the immunohistochemical expression of periostin.

RESULTS

No significant difference was detected in cementum thickness (apical, P = .06; medium, P = .16; cervical, P = .18) between groups. The numbers of fibroblasts in PDL (P = .56), incremental lines of cementum (P = .51) and the immunohistochemical patterns of periostin expression in PDL (P = .68) did not differ between groups.

CONCLUSION

IV BP therapy does not thicken cementum or change the micromorphology of PDL.

Multiple myeloma in the marrow: pathogenesis and treatments

Multiple myeloma (MM) is a B cell malignancy resulting in osteolytic lesions and fractures. In the disease state, bone healing is limited owing to increased osteoclastic and decreased osteoblastic activity, as well as an MM-induced forward-feedback cycle where bone-embedded growth factors further enhance tumor progression as bone is resorbed. Recent work on somatic mutation in MM tumors has provided insight into cytogenetic changes associated with this disease; the initiating driver mutations causing MM are diverse because of the complexity and multitude of mutations inherent in MM tumor cells. This manuscript provides an overview of MM pathogenesis by summarizing cytogenic changes related to oncogenes and tumor suppressors associated with MM, reviewing risk factors, and describing the disease progression from monoclonal gammopathy of undetermined significance to overt MM. It also highlights the importance of the bone marrow microenvironment (BMM) in the establishment and progression of MM, as well as associated MM-induced bone disease, and the relationship of the bone marrow to current and future therapeutics. This review highlights why understanding the basic biology of the healthy and diseased BMM is crucial in the quest for better treatments and work toward a cure for genetically diverse diseases such as MM.

Genetic association between VEGF polymorphisms and BRONJ in the Korean population

OBJECTIVES

The purpose of this study was to evaluate the association between vascular endothelial growth factor (VEGF) polymorphisms and bisphosphonate-related osteonecrosis of the jaw (BRONJ) in the Korean population.

SUBJECTS AND METHODS

Forty-five individuals (2 men, 43 women; mean age: 68.7 ± 12.3 years) were recruited for this study. All visited the Yonsei University Dental Hospital for surgical intervention from January 2012 to January 2013 and had a history of bisphosphonate (BP) administration (oral and/or intravenous). Patients were allocated to case (n = 26) or control (n = 19) groups according to the patients' selection criteria. Association between three VEGF single nucleotide polymorphisms (rs699947 (-2578 C>A), rs2010963 (-634 G>C) and rs3025039 (+936 C>T)) and BRONJ were investigated using multiple logistic regression analysis and Fisher's exact test where appropriate (α = 0.05).

RESULTS

The CC homozygotes of rs2010963 and rs3025039 of VEGF gene were associated with an increased risk of BRONJ (P = 0.04, 0.03, respectively). In haplotype analysis, no differences in haplotype C-C (-2578/-634) and haplotype C-C-C (-2578/-634/+936) were observed.

CONCLUSION

The CC homozygotes of rs2010963 and rs3025039 polymorphisms in the VEGF gene were associated with an increased risk of BRONJ in the Korean population. Further epidemiological cohort studies with a larger sample size would be required to confirm the suggestive correlations.

Dynamic interplay between bone and multiple myeloma: emerging roles of the osteoblast

Multiple myeloma is a B-cell malignancy characterized by the unrelenting proliferation of plasma cells. Multiple myeloma causes osteolytic lesions and fractures that do not heal due to decreased osteoblastic and increased osteoclastic activity. However, the exact relationship between osteoblasts and myeloma cells remains elusive. Understanding the interactions between these dynamic bone-forming cells and myeloma cells is crucial to understanding how osteolytic lesions form and persist and how tumors grow within the bone marrow. This review provides a comprehensive overview of basic and translational research focused on the role of osteoblasts in multiple myeloma progression and their relationship to osteolytic lesions. Importantly, current challenges for in vitro studies exploring direct osteoblastic effects on myeloma cells, and gaps in understanding the role of the osteoblast in myeloma progression are delineated. Finally, successes and challenges in myeloma treatment with osteoanabolic therapy (i.e., any treatment that induces increased osteoblastic number or activity) are enumerated. Our goal is to illuminate novel mechanisms by which osteoblasts may contribute to multiple myeloma disease progression and osteolysis to better direct research efforts. Ultimately, we hope this may provide a roadmap for new approaches to the pathogenesis and treatment of multiple myeloma with a particular focus on the osteoblast.

Bisphosphonate-related osteonecrosis of the jaw: an Italian post-marketing surveillance analysis

OBJECTIVE

Although bisphosphonate (BP)-related osteonecrosis of the jaw (BRONJ) is well recognized, little is known about it in terms of pathophysiology, epidemiology or management. We analyzed all suspected BRONJ reports sent to the Italian Pharmacovigilance Adverse Event Spontaneous Reporting System (Rete Nazionale Farmacovigilanza [RNF]) to determine their pattern and add new information about this relevant issue.

RESEARCH DESIGN AND METHODS

All suspected BRONJ sent to the RNF between 2003 and 2011 were retrieved. After a case-by-case assessment procedure, we analyzed BP type, BP exposure time and time since last use.

RESULTS

Between 2003 and 2011, 555 reports of osteonecrosis of the jaw (ONJ) after BP administration were recorded in the RNF. These events occurred mostly in patients affected by cancer (77.84%) in which zoledronate was the most frequently suspected BP. Most patients experienced ONJ after long-term use of the drug (median time of BP exposure being between 1.3 and 8.8 years). Interestingly, 139 (25.05%) cases of ONJ occurred between 2 and 121 months after BP withdrawal.

CONCLUSION

This study shows that BRONJ can occur much earlier than hitherto reported, adds new data on BRONJ onset following ibandronate treatment and reveals that patients who cease BP-based therapy develop ONJ, raising the question of post-treatment monitoring strategies.

Serum YKL-40: a new independent prognostic marker for skeletal complications in patients with multiple myeloma

In a time of increasing treatment options for multiple myeloma bone disease, risk factors predicting progression need to be elucidated. This study investigated the value of serum YKL-40, previously shown to be associated with radiographic progression of bone destruction, as a predictor for time to clinical progression, i.e. skeletal-related events (SREs), in 230 newly diagnosed patients with multiple myeloma receiving intravenous bisphosphonates. Serum concentrations of YKL-40 and biochemical bone markers (CTX-MMP, CTX-I, PINP) were measured at diagnosis. Patients were evaluated every third month for SRE and at 9 and 24 months for radiographic progression. Elevated serum YKL-40 was seen in 47% of patients and associated with high-risk disease (International Staging System stage III; p < 0.001), increased bone resorption (serum CTX/MMP; p < 0.001) and early radiographic progression at 9 months (p = 0.01). Serum YKL-40 together with serum CTX-MMP/PINP ratio and World Health Organization status were independent predictors of time to first SRE.

Investigating osteogenic differentiation in multiple myeloma using a novel 3D bone marrow niche model

Clonal proliferation of plasma cells within the bone marrow (BM) affects local cells, such as mesenchymal stromal cells (MSCs), leading to osteolysis and fatality in multiple myeloma (MM). Consequently, there is an urgent need to find better mechanisms of inhibiting myeloma growth and osteolytic lesion development. To meet this need and accelerate clinical translation, better models of myeloma within the BM are required. Herein we have developed a clinically relevant, three-dimensional (3D) myeloma BM coculture model that mimics bone cell/cancer cell interactions within the bone microenvironment. The coculture model and clinical samples were used to investigate myeloma growth, osteogenesis inhibition, and myeloma-induced abnormalities in MM-MSCs. This platform demonstrated myeloma support of capillary-like assembly of endothelial cells and cell adhesion-mediated drug resistance (CAM-DR). Also, distinct normal donor (ND)- and MM-MSC miRNA (miR) signatures were identified and used to uncover osteogenic miRs of interest for osteoblast differentiation. More broadly, our 3D platform provides a simple, clinically relevant tool to model cancer growth within the bone-useful for investigating skeletal cancer biology, screening compounds, and exploring osteogenesis. Our identification and efficacy validation of novel bone anabolic miRs in MM opens more opportunities for novel approaches to cancer therapy via stromal miR modulation.

Biomarkers of bone remodeling in multiple myeloma patients to tailor bisphosphonate therapy

BACKGROUND

Patients with multiple myeloma may be susceptible to osteonecrosis of the jaw (ONJ) and stress fractures due to long-term aminobisphosphonate (aBP) therapy. However, it is unknown whether urinary N-telopeptide (NTX) or other bone biomarkers are predictive of skeletal-related events (SRE) or the impact of cessation of aBP therapy on bone remodeling.

METHODS

We studied markers of bone turnover over a 6-month period after a single dose of zoledronic acid in 29 patients with multiple myeloma in remission who previously received 8 to 12 doses of pamidronate or zoledronate (NCT00577642). Our primary objective was to determine the duration of time urinary NTX levels remain suppressed after a single dose of zoledronate. A secondary objective was to identify and correlate other markers of bone remodeling with NTX changes. Thirty cytokines, based on their possible role in bone remodeling, were tested using cytokine arrays. Candidates were confirmed by ELISA.

RESULTS

All patients had continued suppression of NTX levels, except 1 patient who had an increase in NTX levels associated with an SRE. GDF-15 and decorin were found to decrease, whereas bone-specific alkaline phosphatase (BSALP) increased. Although not significant in aggregate, osteopontin and osteoprotegerin levels increased in at least half of the patients.

CONCLUSION

Our data show that NTX levels continue to be suppressed after aBP therapy, and suggest that suppressed NTX levels may be predictive of freedom from SRE in this patient population. Furthermore, osteoblast suppression by aBP may be reversible in myeloma. These data provide the basis for less frequent dosing of aBPs.

Tooth alterations in areas of bisphosphonate-induced osteonecrosis

OBJECTIVE

Osteonecrosis of the jaw is a potential side effect when using bisphosphonates. Most studies on the effects of bisphosphonates on teeth have been conducted in vitro or in animal models of tooth development. Therefore, the aim of this study was to describe alterations found in human teeth extracted from areas of bisphosphonate-induced osteonecrosis.

MATERIALS AND METHODS

Using a retrospective study design, 16 teeth from 13 patients were extracted from areas of bisphosphonate-induced osteonecrosis during surgical debridement. The specimens were decalcified and embedded in paraffin. A series of 5-μm sections were prepared, stained with hematoxylin and eosin (H&E) and observed under a light microscope.

RESULTS

The majority of the patients were female (53.85 %), with a mean age of 60.23 ± 13.18 years. Zoledronate (IV) was the most common bisphosphonate used (92.3 %), over a mean period of 2 years. The commonest alteration observed was hypercementosis (87.5 %), followed by pulpar necrosis (81.25 %), pulp stones attached to the dentine and loose pulp stones in the pulp chamber and root canals in addition to linear calcifications (68.75 %), dentinoid/osteoid material formation (18.75 %), and dental ankylosis (6.25 %).

CONCLUSIONS

Patients undergoing bisphosphonate therapy present diverse tooth alterations, which should be closely monitored by clinicians to prevent complications.

CLINICAL RELEVANCE

It is paramount that the teeth involved in oral lesions are always examined. Attention should be drawn to the need to establish preventive measures, in terms of dental treatment, for patients prior to starting bisphosphonate therapy.

Immunomodulatory drugs thalidomide and lenalidomide affect osteoblast differentiation of human bone marrow stromal cells in vitro

Osteoblastic activity is severely impaired in active myeloma, contributing to the development of myeloma bone disease. Although several drugs reducing osteoclast-mediated bone degradation are in clinical use, approaches to specifically augment bone formation are at an early stage of development. Novel antimyeloma drugs not only directly act on myeloma cells, but impact on the microenvironment as well. Proteasome inhibitors were previously shown to have bone anabolic properties. Here we investigated the impact of immunomodulatory drugs (IMiDs) on bone formation. Treatment with thalidomide and lenalidomide significantly inhibited osteoblast development in vitro, as reflected by a reduction of alkaline phosphatase activity and matrix mineralization. The effects were upheld in combination with bortezomib. The IMiDs upregulated Dickkopf-1 (DKK1) and inhibin beta A, but blocking these molecules was not able to restore regular osteoblast development. We therefore performed gene expression profiling to reveal other osteoblast regulatory factors that might be involved in the IMiD-mediated effect on osteoblast development. Our data indicate that osteoblast inhibition is possibly an IMiD-class effect mediated by downregulation of major osteoblast regulators (e.g., runt-related transcription factor 2, distal-less homeobox 5, pleiotrophin) and concurrent induction of secreted inhibitors of osteoblast formation (e.g. DKK1, activin A, gremlin 1). Our results highlight the need for bone anabolic therapeutics in myeloma, counteracting the negative impact of prolonged IMiD exposure on bone metabolism.

Association between CYP2C8 (rs1934951) polymorphism and bisphosphonate-related osteonecrosis of the jaws in patients on bisphosphonate therapy: a meta-analysis

AIMS

Bisphosphonate-related osteonecrosis of the jaws (BONJ) is a severe complication in patients on bisphosphonate therapy. The study was conducted to verify the association between CYP2C8 (rs1934951) polymorphism and BONJ predisposition.

METHODS

The relative epidemiologic studies were identified in PubMed and Embase to conduct a meta-analysis using STATA.

RESULTS

In the pooled analysis with multiple cancer types, patients carrying the CYP2C8 rs1934951 AA or AG genotype showed no significantly increased BONJ susceptibility compared with those carrying the wild GG genotype [dominant: odds ratio (OR) = 2.05, 95% confidence interval (CI) = 0.67-6.29, p = 0.209; recessive: OR = 1.88, 95% CI = 0.23-15.6, p = 0.560; AG vs. GG: OR = 2.07, 95% CI = 0.80-5.32, p = 0.133, and AA vs. GG: OR = 1.34, 95% CI = 0.48-3.74, p = 0.578]. A significant association between AA and AG genotypes of CYP2C8 (rs1934951) and BONJ risk was found in the subgroup analysis of multiple myeloma (dominant: OR = 5.77, 95% CI = 1.21-27.63, p = 0.028; AG vs. GG: OR = 5.02, 95% CI = 2.06-12.23, p = 0.001, and AA vs. GG: OR = 16.23, 95% CI = 1.72-78.7, p = 0.015).

CONCLUSION

The results indicated that AA and AG genotypes of CYP2C8 (rs1934951) might be predictors for multiple myeloma patients at high risk to develop BONJ.

Physical activity participation and barriers for people with multiple myeloma

PURPOSE

This study aims to examine, for people treated for multiple myeloma, (1) differences between prediagnosis and postdiagnosis levels of physical activity, (2) perceived barriers and likelihood of attending a physical activity program, and (3) factors that influence whether or not respondents are meeting physical activity guidelines.

METHODS

This was a quantitative cross-sectional study; data were gathered from a larger Australian population-wide survey. Respondents completed the survey in hard copy, online, or over the telephone. Demographic and clinical variables included age, gender, locality, time since diagnosis, and marital status. The Godin Leisure-Time Questionnaire measured physical activity; barriers and likelihood of participating in a physical activity program were assessed using a five-point Likert scale. Data were analyzed using descriptive, bivariate, and multivariate analyses.

RESULTS

Of the 229 respondents, 53.1 % were male, 42 % aged 60-69 years, and 75.7 % were married or in a de facto relationship. Participation in physical activity declined significantly from prediagnosis levels. Fatigue, injuries, and pain were the strongest perceived barriers to participation; 41 % reported they were likely to attend an exercise program if offered. Respondents who were sufficiently active before diagnosis were 4.79 times more likely to be sufficiently active posttreatment.

CONCLUSIONS

People with multiple myeloma reported very low levels of physical activity across all levels of intensity; however, they were interested in attending a physical activity program. To increase physical activity among people with multiple myeloma, interventions should target perceived barriers with a particular focus on those who were not physically active prior to diagnosis.

Atypical femur fractures among breast cancer and multiple myeloma patients receiving intravenous bisphosphonate therapy

PURPOSE

Atypical femur fractures represent a potential complication of chronic oral bisphosphonate therapy in women with osteoporosis, but the risk of atypical femur fractures among cancer patients receiving intravenous bisphosphonates at higher cumulative doses remains unclear. We examined femur fractures occurring in cancer patients treated with intravenous bisphosphonates (IVBP) to determine whether a subset may be atypical fractures.

METHODS

Between 2005 and 2010, we identified patients with known IVBP therapy for multiple myeloma or metastatic breast cancer, who subsequently sustained a femur fracture based on hospitalization, oncology, pharmacy and chemotherapy visit records. Radiographs were examined by an orthopedic surgeon to determine anatomic fracture site and pattern. An atypical fracture was defined as a transverse or short oblique fracture occurring below the lesser trochanter with evidence of focal hypertrophy of the lateral cortex and absence of biopsy-proven malignancy or radiation therapy at the fracture site.

RESULTS

A total of 62 patients with breast cancer (N=39) or multiple myeloma (N=23) with femur fracture and prior IVBP treatment for bone malignancy were identified. There were 30 proximal hip, 18 subtrochanteric and 14 femoral shaft fractures. Intraoperative bone samples were sent in 29 of 58 fracture cases undergoing operative repair, with 76% positive for malignancy. Six cases (4 breast cancer, 2 multiple myeloma) of atypical femur fracture were identified, two with negative intraoperative pathology and four with no bone biopsy samples sent. Five of the six patients with atypical fracture had bilateral femur findings, including two with transverse fracture in the contralateral femur and three with focal hypertrophy of the contralateral cortex. Two atypical fracture cases also experienced osteonecrosis of the jaw compared to 3 in the remaining cohort (33% vs. 5%, p=0.07). Patients with atypical fracture received more IVBP (median 55 vs. 15 doses) and zoledronic acid (32 vs. 12 doses) and had longer treatment duration (median 5.9 vs. 1.6 years) compared to patients without atypical fracture (all p≤0.01).

CONCLUSIONS

Among 62 patients who received IVBP for skeletal malignancy and experienced a femur fracture, we identified six cases of atypical fracture. While fractures in this population are often assumed to be pathologic, prospective studies investigating fracture pattern, microscopic bone pathology and pharmacologic exposures should be conducted to further examine the association of IVBP and atypical femur fractures.