Optimal use of bisphosphonates in patients with multiple myeloma

Fracture rate after conventional external beam radiation therapy to the spine in multiple myeloma patients

BACKGROUND CONTEXT

Conventional external beam radiation therapy (cEBRT) is used in multiple myeloma (MM) to treat severe pain, spinal cord compression, and disease-related bone disease. However, radiation may be associated with an increased risk of vertebral compression fractures (VCFs), which could substantially impair survival and quality of life. Additionally, the use of the Spinal Instability Neoplastic Score (SINS) in MM is debated in MM.

PURPOSE

To determine the incidence of VCFs after cEBRT in patients with MM and to assess the applicability of the SINS score in the prediction of VCFs in MM.

STUDY DESIGN

Retrospective multicenter cohort study.

PATIENT SAMPLE

MM patients with spinal myeloma lesions who underwent cEBRT between January 2010 and December 2021.

OUTCOME MEASURES

Frequency of new or progressed VCFs and subdistribution hazard ratios for potentially associated factors.

METHODS

Patient and treatment characteristics were manually collected from the patients' electronic medical records. Computed tomography (CT) scans from before and up to 3 years after the start of radiation were used to score radiographic variables at baseline and at follow-up. Multivariable Fine and Gray competing risk analyses were performed to evaluate the diagnostic value of the SINS score to predict the postradiation VCF rate.

RESULTS

A total of 127 patients with 427 eligible radiated vertebrae were included in this study. The mean age at radiation was 64 years, and 66.1% of them were male. At the start of radiation, 57 patients (44.9%) had at least one VCF. There were 89 preexisting VCFs (18.4% of 483 vertebrae). Overall, 39 of 127 patients (30.7%) reported new fractures (number of vertebrae (n)=12) or showed progression of existing fractures (n=36). This number represented 11.2% of all radiated vertebrae. Five of the 39 (12.8%) patients with new or worsened VCFs received an unplanned secondary treatment (augmentation [n=2] or open surgery [n=3]) within 3 years. Both the total SINS score (SHR 1.77; 95% confidence interval (CI) 1.54-2.03; p<.001) and categorical SINS score (SHR 10.83; 95% CI 4.20-27.94; p<.001) showed an independent association with higher rates of new or progressed VCFs in adjusted analyses. The use of bisphosphonates was independently associated with a lower rate of new or progressed VCFs (SHR 0.47 [95% CI 0.24-0.92; p=.027]).

CONCLUSIONS

This study demonstrated that new or progressed VCFs occurred in 30.7% of patients within 3 years, in a total of 11.2% of vertebrae. The SINS score was found to be independently associated with the development or progression of VCFs and could thus be applied in MM for fracture prediction and possibly prevention.

Smoldering multiple myeloma - Past, present, and future

Smoldering multiple myeloma (SMM) routinely precedes the development of multiple myeloma. While some patients experience aggressive disease, others have more indolent courses akin to those with monoclonal gammopathy of undetermined significance. Much effort has been made to understand the pathobiological basis of this heterogeneity. Scientific advancements have led to the emergence of various clinical and genomic markers of relevance, translating into evolution of disease definitions over time. More recently, the interest in manipulation of biological pathways has intensified in a bid to stall or halt disease progression. Studies with lenalidomide have exemplified the promise of early intervention, whereas numerous therapeutic approaches remain the subject of ongoing clinical investigation. This review summarizes the historic progress made in defining SMM as a distinct clinicopathologic entity, provides a critical appraisal of the evidence guiding risk assessment, and suggests a pragmatic approach to its modern-day management. Finally, an overview of developments on the horizon is also provided.

Racial Disparities in Intravenous Bisphosphonate Use Among Older Patients With Multiple Myeloma Enrolled in Medicare

PURPOSE

Intravenous (IV) bisphosphonates reduce the risk of skeletal-related events in patients with multiple myeloma (MM). However, data describing racial differences in IV bisphosphonate utilization outside of clinical trial settings are limited. We evaluated population-level IV bisphosphonate initiation and discontinuation among patients of age ≥ 65 years with MM.

METHODS

We conducted a retrospective cohort study of patients of age ≥ 65 years diagnosed with first primary MM between 2001 and 2011. Patients were identified using the SEER-Medicare linked database and followed through December 2013. Cumulative incidences of IV bisphosphonate initiation and time to discontinuation among users were compared between racial and ethnic groups. In Fine and Gray competing risk models, we estimated subdistribution hazard ratios (SHRs) and 95% CIs for initiation and discontinuation.

RESULTS

We included 14,231 eligible patients with MM (median age, 76 years; 52% male). Over a median follow-up of 23.1 months, 54% of patients received at least one IV bisphosphonate dose. Our final analytical sample included 10,456 non-Hispanic (NH) Whites, 2,267 NH Blacks, 548 Asian and Pacific islanders, and 815 Hispanic and Latino patients. A higher proportion of White patients (56.1%) newly received IV bisphosphonates after MM diagnosis compared with NH Blacks (45.4%). Compared with White patients, NH Black patients were less likely to initiate IV bisphosphonates (SHR, 0.74; 95% CI, 0.70 to 0.79) and slightly more likely to discontinue treatment (SHR, 1.10; 95% CI, 1.01 to 1.19).

CONCLUSION

Approximately half of the patients with MM of age ≥ 65 years did not receive IV bisphosphonates, with significant delay among racial minority groups. These findings highlight the need for improvement of IV bisphosphonate uptake in patients with MM of age ≥ 65 years.

Multiple Myeloma Bone Disease: Implication of MicroRNAs in Its Molecular Background

Multiple myeloma (MM) is a common hematological malignancy arising from terminally differentiated plasma cells. In the majority of cases, symptomatic disease is characterized by the presence of bone disease. Multiple myeloma bone disease (MMBD) is a result of an imbalance in the bone-remodeling process that leads to increased osteoclast activity and decreased osteoblast activity. The molecular background of MMBD appears intriguingly complex, as several signaling pathways and cell-to-cell interactions are implicated in the pathophysiology of MMBD. MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate the expression of their target mRNAs. Numerous miRNAs have been witnessed to be involved in cancer and hematological malignancies and their role has been characterized either as oncogenic or oncosuppressive. Recently, scientific research turned towards miRNAs as regulators of MMBD. Scientific data support that miRNAs finely regulate the majority of the signaling pathways implicated in MMBD. In this review, we provide concise information regarding the molecular pathways with a significant role in MMBD and the miRNAs implicated in their regulation. Moreover, we discuss their utility as molecular biomarkers and highlight the putative usage of miRNAs as novel molecular targets for targeted therapy in MMBD.

Keeping an Eye on Bisphosphonate Therapy in Myeloma: A Case Report of Ocular Inflammation Postzoledronic Acid Infusion

Bisphosphonates have evolved over the past decades from oral to more potent intravenous preparations. Along with significant paradigm shift in the management of myeloma over the past years, stronger nitrogen-containing bisphosphonates, due to their antiresorptive action on the bones, have found their way as a key and integral part in the management of bone disease in myeloma. Multiple randomized controlled trials have established efficacy of bisphosphonates in reducing skeletal-related events in myeloma. Some well-documented adverse events include acute-phase reactions, esophageal irritation, and osteonecrosis of the jaw. Across all clinical indications, the incidence of inflammatory eye reactions after bisphosphonate infusion ranges from 0.046% to 1%. However, data from myeloma patients are extrapolated from few reported cases in literature with varying management strategies including discontinuation, switching to different forms, and rechallenging with steroid cover. Inflammatory eye reactions can vary from self-limiting conjunctivitis and episcleritis to serious uveitis and vision-threatening orbital inflammation. We present a similar case of a patient with IgG kappa myeloma who developed flu-like symptoms followed by severe orbital inflammation within 48–72 hours after receiving zoledronic acid infusion. The patient was successfully managed with intravenous methyl prednisolone followed by oral tapering dose of steroids and discontinuation of further bisphosphonate therapy. A complete recovery was noted in a week's time.

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.

Use of bisphosphonates in multiple myeloma patients in Denmark, 2005-2015

PURPOSE

To describe use of bisphosphonates in newly diagnosed multiple myeloma patients in Denmark.

METHODS

Using data from the Danish National Multiple Myeloma Registry, we conducted a population-based cohort study. Among patients newly diagnosed with multiple myeloma from 2005 to 2015, we examined use of bisphosphonates at first- and at progression/second-line anti-myeloma treatment overall, by patient characteristics, and myeloma complications.

RESULTS

Of 2947 patients starting first-line anti-myeloma treatment, 2207 patients (74.9%) received bisphosphonates. During a median follow-up of 27.6 (quartiles, 10.6-52.5) months, disease progression post-first-line treatment was recorded in 1546 patients, of whom 1065 (68.9%) were treated with bisphosphonates. Altogether, 80.9% of patients with and 37.6% of patients without myeloma bone disease were treated with bisphosphonates at first line and 73.0% and 42.7%, respectively, at progression/second line. Moreover, the proportion of patients treated with bisphosphonates decreased with increasing severity of renal impairment at first and at progression/second-line treatment.

CONCLUSION

The proportion of patients treated with bisphosphonates as part of first- and second-line anti-myeloma treatment increased with presence of myeloma bone disease and decreased by presence and severity of renal impairment. Overall, 25% of newly diagnosed multiple myeloma patients had no record of bisphosphonate treatment, potentially indicating an unmet need.

Monoclonal antibodies against RANKL and sclerostin for myeloma-related bone disease: can they change the standard of care?

Introduction: Over 80% of the patients with multiple myeloma (MM) develop myeloma bone disease (MBD) during the disease course. The clinical consequences include serious skeletal-related events (SRE) that impact survival and quality of life. Bisphosphonates are the mainstay in the treatment of MBD. Currently, new therapeutic strategies are being introduced and broaden the therapeutic options in MBD. Areas covered: The purpose of this review is to summarize the current clinical management of MBD and present novel data regarding monoclonal antibodies against the receptor activator of NF-kappa B ligand (RANKL) and sclerostin that may change the clinical practice. Expert opinion: Our better understanding of the pathophysiology of MBD has identified several factors as potential therapeutic targets. Recent data have shown that the RANKL inhibitor denosumab constitutes a new promising option. The non-inferiority compared with bisphosphonates in terms of SRE prevention, the potential survival benefit, the convenience of subcutaneous administration, and the favorable toxicity profile makes denosumab a valuable alternative for physicians in the current treatment of MBD. Anti-sclerostin antibodies are currently under clinical development. Further investigations are needed to address open questions in the field including the value of anabolic agents combined with anti-resorptive and anti-MM drugs in MBD.

Dental implant in a multiple myeloma patient undergoing bisphosphonate therapy: A case report

Dental implant placement in patients with multiple myeloma undergoing bisphosphonates therapy could be accomplished; however, it can turn into a successful treatment for edentulous area and functionally stabilized for many years. But a meticulous case selection, proper medical consultation with physician, minimally invasive surgery, and other cautions must be considered.

Myeloma bone disease: from biology findings to treatment approaches

Bone disease is a cardinal complication of multiple myeloma that affects quality of life and survival. Osteocytes have emerged as key players in the development of myeloma-related bone disease. Along with other factors, they participate in increased osteoclast activity, decreased osteoblast function, and immunosuppressed marrow microenvironment, which deregulate bone turnover and result in bone loss and skeletal-related events. Denosumab is a novel alternative to bisphosphonates against myeloma bone disease. Special considerations in this constantly evolving field are thoroughly discussed.

Use of Bisphosphonates in Elderly Patients With Newly Diagnosed Multiple Myeloma

Background: Bisphosphonates reduce skeletal-related events (SREs) in patients with multiple myeloma (MM) and, in some studies, improved survival. Since 2011, bisphosphonate use has been recommended by NCCN for all patients with newly diagnosed MM receiving antineoplastic therapy independent of the presence of bone disease. This study investigated their use after these guidelines were established. Methods: We identified patients aged ≥65 years in the SEER-Medicare database with newly diagnosed MM between January 1, 2012, and December 31, 2013, who received antineoplastic therapy, had ≥6 months of follow-up, and did not receive prior bisphosphonates. Presence of SREs at diagnosis was identified, including pathologic fracture, spinal cord compression, radiation to bone, or surgery to bone. Use of bisphosphonates was defined as having ≥1 claim for an intravenous or oral bisphosphonate within 6 months after the start of antineoplastic therapy. We used multivariable modeling to compare users with nonusers, controlling for demographic and clinical covariates. We compared overall survival between users and nonusers using proportional hazards analysis. Results: Of 1,309 patients identified, 720 (55%) used a bisphosphonate. Factors associated with use included SRE at diagnosis (adjusted odds ratio [AOR], 2.60; 95% CI, 1.98-3.40), hypercalcemia (AOR, 1.74; 95% CI, 1.26-2.41), and use of proteasome inhibitor + immunomodulatory imide therapy (AOR, 1.70; 95% CI, 1.21-2.39). Chronic kidney disease (AOR, 0.48; 95% CI, 0.35-0.66) was associated with decreased use. Bisphosphonate use was associated with reduced mortality (hazard ratio, 0.70; 95% CI, 0.56-0.88). Conclusions: Although bisphosphonate use is recommended for all patients with newly diagnosed MM receiving antineoplastic therapy, 45% of patients in the United States did not receive this guideline-recommended care.

Bisphosphonate guidelines for treatment and prevention of myeloma bone disease

Multiple myeloma (MM) is a haematological malignancy characterised by the clonal proliferation of plasma cells in the bone marrow. More than 80% of patients with MM display evidence of myeloma bone disease (MBD), characterised by the formation of osteolytic lesions throughout the axial and appendicular skeleton. MBD significantly increases the risk of skeletal-related events such as pathologic fracture, spinal cord compression and hypercalcaemia. MBD is the result of MM plasma cells-mediated activation of osteoclast activity and suppression of osteoblast activity. Bisphosphonates (BP), pyrophosphate analogues with high bone affinity, are the only pharmacological agents currently recommended for the treatment and prevention of MBD and remain the standard of care. Pamidronate and zoledronic acid are the most commonly used BP to treat MBD. Although generally safe, frequent high doses of BP are associated with adverse events such as renal toxicity and osteonecrosis of the jaw. As such, optimal duration and dosing of BP therapy is required in order to minimise BP-associated adverse events. The following guidelines provide currently available evidence for the adoption of a tailored approach when using BP for the management of MBD.

Bone-targeted agents in multiple myeloma

Osteolytic bone disease, characterized by bone pain, increased risk of pathologic fractures, tumor-induced hypercalcemia known as skeletal-related events (SREs), is a frequent complication of patients with multiple myeloma (MM) and persists even in the absence of active disease, resulting in a major cause of morbidity and mortality. The interaction between myeloma cells and their surrounding cells in the bone marrow (BM) microenvironment promotes both myeloma cell growth and bone destruction and forms the vicious cycle of MM bone disease. Therefore, therapeutic strategies targeting the interaction between myeloma cells and cellular components including osteoclasts (OCs), stromal cells and osteoblasts (OBs) in the BM is crucial not only to attain tumor regression but also to prevent or delay the incidence of SREs, which leads to improve survival and quality of life in affected patients. Recently, several novel targets which act on components of the cycle for treating MM-associated bone disease have been identified in addition to current treatments including nitrogen-containing bisphosphonates. This review focuses on the overview of pathophysiology in MM-associated bone disease and summarizes its current clinical management. Several novel bone-targeted agents in preclinical setting will be also discussed.

Pathogenesis of bone disease in multiple myeloma: from bench to bedside

Osteolytic bone disease is the hallmark of multiple myeloma, which deteriorates the quality of life of myeloma patients, and it affects dramatically their morbidity and mortality. The basis of the pathogenesis of myeloma-related bone disease is the uncoupling of the bone-remodeling process. The interaction between myeloma cells and the bone microenvironment ultimately leads to the activation of osteoclasts and suppression of osteoblasts, resulting in bone loss. Several intracellular and intercellular signaling cascades, including RANK/RANKL/OPG, Notch, Wnt, and numerous chemokines and interleukins are implicated in this complex process. During the last years, osteocytes have emerged as key regulators of bone loss in myeloma through direct interactions with the myeloma cells. The myeloma-induced crosstalk among the molecular pathways establishes a positive feedback that sustains myeloma cell survival and continuous bone destruction, even when a plateau phase of the disease has been achieved. Targeted therapies, based on the better knowledge of the biology, constitute a promising approach in the management of myeloma-related bone disease and several novel agents are currently under investigation. Herein, we provide an insight into the underlying pathogenesis of bone disease and discuss possible directions for future studies.

Genetic factors related with early onset of osteonecrosis of the jaw in patients with multiple myeloma under zoledronic acid therapy

Specific genetic polymorphisms (SNPs) have been correlated with the development of bisphosphonate-related osteonecrosis of the jaw (BRONJ) in small series. We screened 140 myeloma patients (36 patients with and 104 without BRONJ) for the presence of previously identified SNPs in PPARG and CYP2C8 genes. All the patients received exclusively zolendronic acid (ZA) therapy and were followed prospectively for BRONJ. SNPs in both genes were associated with a higher risk of development of early BRONJ, occurring within less than 2 years of ZA therapy (59% vs. 16%, p = .022 for PPARG and 29% vs. 7%, p = .07 for CYP2C8) and a shorter time to develop BRONJ (59% versus 12%, p = .011 for PPARG and 29% versus 0% at 2 years, p = .037 for CYP2C8), independently of indices of poor oral hygiene. Thus, although preliminary, our data indicate that the presence of SNPs in PPARG and CYP2C8 genes may be associated with increased risk of early BRONJ.

Molecular mechanisms, current management and next generation therapy in myeloma bone disease

Multiple myeloma (MM) bone disease is a major cause of morbidity and mortality in MM patients and persists even in patients in remission. This bone disease is caused by an uncoupling of bone remodeling, with increased osteoclast and decreased osteoblast activity and formation, culminating in lytic bone destruction. Bisphosphonates are the current standard of care but new therapies are needed. As the molecular mechanisms controlling MM bone disease are increasingly well understood, new therapeutic targets are extensively explored in the preclinical setting and initial clinical trials with novel compounds now show promising results. In this review, we will provide a comprehensive overview of the biology of MM bone disease, summarize its current clinical management and discuss preclinical and clinical data on next generation therapies.

Economic burden of relapsed or refractory multiple myeloma: Results from an international trial

OBJECTIVE

The direct cost of relapsed or refractory multiple myeloma (RRMM) is documented; indirect costs are being explored. Healthcare payers seek cost-offsets from therapies that improve clinical outcomes but challenge budgets; employers seek lower absenteeism and better productivity. Study goals were to: (i) identify direct and indirect economic factors of RRMM, and (ii) explore longitudinal relationships between clinical, economic, and health-related quality of life (HRQoL) assessments.

METHODS

Economic questionnaire, clinical, and HRQoL data from a multisite, international, randomized, controlled study in RRMM were analyzed.

RESULTS

Patients (n=263) were 53.6% male, 91.6% Caucasian; mean age of 62.9 years, median Eastern Cooperative Oncology Group status of 1 (56.3%). Moderate to severe pain or fatigue was reported by 30.4% and 70.6%, respectively. At baseline, ≥1 hospitalization was reported by 107 (41.8%); 182 (71.1%) and 86 (33.6%) reported specialist and family physician visits, respectively. A total of 28 (10.8%) were working: 10 (37.0%) of which reported RRMM-driven absenteeism ≥1 day. Of those who were not working, 110 (48.2%) indicated that it was due to RRMM. Multivariate modeling showed lower hospitalization with a major tumor response (β=-1.44, CI: -2.89 to 0.01, P=.05).

CONCLUSIONS

Substantial RRMM indirect, social costs were observed. Better major tumor response may reduce hospital visits.

Emerging treatment approaches for myeloma-related bone disease

INTRODUCTION

Multiple myeloma is characterized by the presence of osteolytic lesions that leads to devastating skeletal-related events in the majority of patients. Myeloma bone disease is attributed to increased osteoclastic and suppressed osteoblastic activity. Areas covered: Bisphosphonates remain the main treatment option, however they have limitations on their own. Understanding the pathogenesis of myeloma bone disease may provide a roadmap for new therapeutic approaches. The pathway of RANKRANKLOPG pathway has revealed denosumab, a monoclonal antibody targeting RANKL as a novel emerging therapy for myeloma-related bone disease. Furthermore, the Wnt signaling inhibitors dicckopf-1 and sclerostin that are implicated in the pathogenesis of bone destruction of myeloma are now targeted by novel monoclonal antibodies. Activin-A is a TGF-beta superfamily member which increases osteoclast activity and inhibits osteoblast function in myeloma; sotatercept and other molecules targeting activin-A have entered into clinical development. Several other molecules and pathways that play an important role in the pathogenesis of bone destruction in myeloma, such as periostin, adiponectin, Notch and BTK signaling are also targeted in an attempt to develop novel therapies for myeloma-related bone disease. Expert commentary: We summarize the current advances in the biology of myeloma bone disease and the potential therapeutic targets.

Stereoselective Synthesis of Homoneryl and Homogeranyl Triazole Bisphosphonates

Isoprenoid-substituted bisphosphonates are known to serve as inhibitors of the enzyme geranylgeranyl diphosphate synthase, and their activity can be highly sensitive to olefin stereochemistry. A mixture of homogeranyl and homoneryl triazole bisphosphonates has previously demonstrated potent activity, and thus stereocontrolled syntheses of the individual isomers have been developed.

A new motif for inhibitors of geranylgeranyl diphosphate synthase

The enzyme geranylgeranyl diphosphate synthase (GGDPS) is believed to receive the substrate farnesyl diphosphate through one lipophilic channel and release the product geranylgeranyl diphosphate through another. Bisphosphonates with two isoprenoid chains positioned on the α-carbon have proven to be effective inhibitors of this enzyme. Now a new motif has been prepared with one isoprenoid chain on the α-carbon, a second included as a phosphonate ester, and the potential for a third at the α-carbon. The pivaloyloxymethyl prodrugs of several compounds based on this motif have been prepared and the resulting compounds have been tested for their ability to disrupt protein geranylgeranylation and induce cytotoxicity in myeloma cells. The initial biological studies reveal activity consistent with GGDPS inhibition, and demonstrate a structure-function relationship which is dependent on the nature of the alkyl group at the α-carbon.

Physiologic Activity of Bisphosphonates – Recent Advances

Background:

Bisphosphonates are drugs commonly used for the medication and prevention of diseases caused by decreased mineral density. Despite such important medicinal use, they display a variety of physiologic activities, which make them promising anti-cancer, anti-protozoal, antibacterial and antiviral agents.

Objective:

To review physiological activity of bisphosphonates with special emphasis on their ongoing and potential applications in medicine and agriculture.

Method:

Critical review of recent literature data.

Results:

Comprehensive review of activities revealed by bisphosphonates.

Conclusion:

although bisphosphonates are mostly recognized by their profound effects on bone physiology their medicinal potential has not been fully evaluated yet. Literature data considering enzyme inhibition suggest possibilities of far more wide application of these compounds. These applications are, however, limited by their low bioavailability and therefore intensive search for new chemical entities overcoming this shortage are carried out.

Canadian recommendations for the management of breakthrough cancer pain

Breakthrough cancer pain (btcp) represents an important element in the spectrum of cancer pain management. Because most btcp episodes peak in intensity within a few minutes, speed of medication onset is crucial for proper control. In Canada, several current provincial guidelines for the management of cancer pain include a brief discussion about the treatment of btcp; however, there are no uniform national recommendations for the management of btcp. That lack, accompanied by unequal access to pain medication across the country, contributes to both regional and provincial variability in the management of btcp. Currently, immediate-release oral opioids are the treatment of choice for btcp. This approach might not always offer optimal speed for onset of action and duration to match the rapid nature of an episode of btcp. Novel transmucosal fentanyl formulations might be more appropriate for some types of btcp, but limited access to such drugs hinders their use. In addition, the recognition of btcp and its proper assessment, which are crucial steps toward appropriate treatment selection, remain challenging for many health care professionals. To facilitate appropriate management of btcp, a group of prominent Canadian specialists in palliative care, oncology, and anesthesiology convened to develop a set of recommendations and suggestions to assist Canadian health care providers in the treatment of btcp and the alleviation of the suffering and discomfort experienced by adult cancer patients.

Current Controversies in the Management of Myeloma Bone Disease

Recent significant advances in the treatment of multiple myeloma have resulted in an improvement in median overall survival from 4.6 years, for patients diagnosed between 2001 and 2005, to 6.1 years, for those diagnosed between 2006 and 2010 (Kumar et al., 2014). However, myeloma bone lesions persist in the absence of active disease and continue to be frequent and significant causes of patient morbidity and contribute to mortality. While bisphosphonate therapy in combination with anti-myeloma therapy remains the cornerstone of skeletal disease management in myeloma, open questions regarding the optimal management of patients with myeloma bone disease remain. This article will address when to initiate and stop bone-targeted therapy in patients with monoclonal gammopathies, duration of bisphosphonate treatment in the era of more effective anti-myeloma treatment, the role of bone resorption markers in determining the dosing schedule for anti-resorptive therapy, risks and benefits of long term anti-resorptive therapy, and whether anti-resorptive therapies should be stopped to enhance the potential anabolic effects of proteasome antagonists and other anabolic agents. J. Cell. Physiol. 231: 2374-2379, 2016. © 2016 Wiley Periodicals, Inc.

Autophagy in bone: Self-eating to stay in balance

Autophagy, a major catabolic pathway responsible of the elimination of damaged proteins and organelles, is now recognized as an anti-aging process. In addition to its basal role in cell homeostasis, autophagy is also a stress-responsive mechanism for survival purposes. Here, we review recent literature to highlight the autophagy role in the different bone cell types, i.e., osteoblasts, osteoclasts and osteocytes. We also discuss the effects of autophagy modulators in bone physiology and of bone anabolic compounds in autophagy. Finally, we analyzed studies regarding bone cell autophagy-deficient mouse models to obtain a more general view on how autophagy modulates bone physiology and pathophysiology, particularly during aging.

Gambogic acid inhibits multiple myeloma mediated osteoclastogenesis through suppression of chemokine receptor CXCR4 signaling pathways

Bone disease, characterized by the presence of lytic lesions and osteoporosis is the hallmark of multiple myeloma (MM). Stromal cell-derived factor 1α (SDF-1α) and its receptor, CXC chemokine receptor 4 (CXCR4), has been implicated as a regulator of bone resorption, suggesting that agents that can suppress SDF1α/CXCR4 signaling might inhibit osteoclastogenesis, a process closely linked to bone resorption. We, therefore, investigated whether gambogic acid (GA), a xanthone, could inhibit CXCR4 signaling and suppress osteoclastogenesis induced by MM cells. Through docking studies we predicted that GA directly interacts with CXCR4. This xanthone down-regulates the expression of CXCR4 on MM cells in a dose- and time-dependent manner. The down-regulation of CXCR4 was not due to proteolytic degradation, but rather GA suppresses CXCR4 mRNA expression by inhibiting nuclear factor-kappa B (NF-κB) DNA binding. This was further confirmed by quantitative chromatin immunoprecipitation assay, as GA inhibits p65 binding at the CXCR4 promoter. GA suppressed SDF-1α-induced chemotaxis of MM cells and downstream signaling of CXCR4 by inhibiting phosphorylation of Akt, p38, and Erk1/2 in MM cells. GA abrogated the RANKL-induced differentiation of macrophages to osteoclasts in a dose- and time-dependent manner. In addition, we found that MM cells induced differentiation of macrophages to osteoclasts, and that GA suppressed this process. Importantly, suppression of osteoclastogenesis by GA was mediated through IL-6 inhibition. Overall, our results show that GA is a novel inhibitor of CXCR4 expression and has a strong potential to suppress osteoclastogenesis mediated by MM cells.

[Multiple myeloma]

Multiple myeloma (MM) is a cancer originating from terminally differentiated B lymphocytes, the plasma cells and is classified as a B cell non-Hodgkin lymphoma. As clonal plasma cells secrete immunoglobulin molecules (lacking antigenic specificity), an "M component" can incidentally be detected. Besides intact immunoglobulin molecules, free light chains can be produced. Although there is no specific treatment for monoclonal gammopathy of undetermined significance (MGUS), which is the defined as the presence of clonal bone marrow plasma cells and low levels (serum and/or urine) of the M component, it should be followed up in affected individuals. The symptoms of MM are numerous and often nonspecific. Diagnosis includes the quantification of monoclonal proteins in serum and urine, blood count, electrolytes and renal function, imaging of the skeleton and bone marrow puncture. The cornerstone of therapy includes melphalan- or cyclophosphamide-based regimens incorporating one of the "novel drugs" (i.e. bortezomib, thalidomide, or lenalidomide).

Severe hypocalcemia after denosumab in a patient with acquired Fanconi syndrome

We report the case of a 48-year-old man with acquired Fanconi syndrome due to IgG-kappa monoclonal gammopathy, who received a single dose of denosumab 60 mg for secondary prevention of skeletal fractures, in conjunction with oral calcium and vitamin D supplementation. The treatment was complicated with a severe, symptomatic hypocalcemia occurring 1 month after the injection and necessitating 4 weeks of intravenous calcium gluconate therapy. Similarly to bisphosphonates, inhibitors of the receptor activator of nuclear factor kappa-B ligand may not be appropriate for the treatment of acquired Fanconi syndrome and other forms of osteomalacia regardless of the degree of renal insufficiency and vitamin D levels. Clinicians should carefully interpret the radiographic and bone densitometry results in light of diverse mechanisms of bone demineralization and potential dependence of calcium homeostasis on high bone turnover.

Myeloma bone disease: Pathophysiology and management

Multiple myeloma bone disease is marked by severe dysfunction of both bone formation and resorption and serves as a model for understanding the regulation of osteoblasts (OBL) and osteoclasts (OCL) in cancer. Myeloma bone lesions are purely osteolytic and are associated with severe and debilitating bone pain, pathologic fractures, hypercalcemia, and spinal cord compression, as well as increased mortality. Interactions within the bone marrow microenvironment in myeloma are responsible for the abnormal bone remodeling in myeloma bone disease. Myeloma cells drive bone destruction that increases tumor growth, directly stimulates the OCL formation, and induces cells in the marrow microenvironment to produce factors that drive OCL formation and suppress OBL formation. Factors produced by marrow stromal cells and OCL promote tumor growth through direct action on myeloma cells and by increasing angiogenesis. Current therapies targeting MMBD focus on preventing osteoclastic bone destruction; however regulators of OBL inhibition in MMBD have also been identified, and targeted agents with a potential anabolic effect in MMBD are under investigation. This review will discuss the mechanisms responsible for MMBD and therapeutic approaches currently in use and in development for the management of MMBD.