Primary epiphyseal arteriopathy in a mouse model of steroid-induced osteonecrosis

[Osteonecrosis-severe side effect of treatment for acute lymphoblastic leukemia]

Osteonecrosis occurs as an acute and long-term serious side effect in children, adolescents, and adults with acute lymphoblastic leukemia. It is associated with severe pain and reduced mobility, ultimately leading to joint destruction and significant long-term morbidity. The cumulative incidence ranges from 11 to 20% in adolescents and young adults. In symptomatic patients, multiple joints are frequently affected, which in turns poses a risk factor for the development of severe osteonecrosis. The genesis of leukemia-associated osteonecrosis is multifactorial. Risk factors include the use of corticosteroids and asparaginase. These exert their effects on the blood supply to the bone through hypercholesterolemia, hypertriglyceridemia, and hypertension. Bacteriemia, genetic susceptibility, and stem cell transplantation pose additional risk factors. The treatment of osteonecrosis is challenging and not evidence based. Preventive measurements have as yet mainly been tested in preclinical models.

Canine Idiopathic Arteriopathy, Appendicular Bone Infarcts, and Neoplastic Transformation of Bone Infarcts in 108 Dogs (Canis lupus familiaris)

Osteosarcoma (OSA) is the most common primary bone tumor in both dogs and humans. The dog is an important research model for OSA, yet dogs have much higher prevalence of bone tumors than do humans, a disparity that has yet to be explained. Neoplastic transformation of cells within or adjacent to bone infarcts into primary bone tumors has been described in humans but only sparsely characterized in the veterinary literature. In this study, 653 cases of canine bone infarcts were received through a referral veterinary osteopathology service over a 14-y period. We identified an idiopathic disorder affecting the nutrient artery, termed canine idiopathic arteriopathy (CIA), which to our knowledge has no direct counterpart in human medicine. This disorder was documented alongside ischemic necrosis of the medullary cavity in 114 bone infarcts in 108 dogs. We hypothesize that CIA precipitated an ischemic environment, resulting in development of a bone infarct down- stream of the abnormal artery. In 52% (59 of 114) of cases, bone infarcts demonstrated evidence of repair (termed reparative bone infarcts [RBI]), while in 48% (55 of 114) of infarcts, a bone tumor was also present, including pleomorphic sarcoma, OSA, fibrosarcoma, and chondrosarcoma. In some cases, a spectrum of tumors was present. We hypothesize that the ischemic infarct environment provoked bone marrow mesenchymal stem cells (MSCs) to attempt repair of the stroma, and in approximately half of cases, MSCs underwent neoplastic transformation (BINT) to produce tumors. The most common sites of bone infarcts were the distal femur, distal radius, proximal humerus, and distal tibia, coinciding with common sites of canine OSA. The authors propose that CIA leading to bone infarcts and infarct-derived tumors, in combination with possible underdiagnosis of canine bone infarcts and misdiagnosis of some RBI as neoplasia, may contribute to the higher reported proportion of bone tumors in dogs compared with humans.

Dasatinib does not exacerbate dexamethasone-induced osteonecrosis in murine models of acute lymphoblastic leukemia therapy

INTRODUCTION

There are clinical reports that the incorporation of dasatinib may increase the frequency of osteonecrosis in acute lymphoblastic leukemia (ALL) treatment regimens. No rigorous testing of this hypothesis is available to guide clinicians.

METHODS

We tested whether oral dasatinib increased the frequency of dexamethasone-induced osteonecrosis in a murine model and tested its effects on dexamethasone's antileukemic efficacy in a murine BCR-ABL⁺ model of ALL.

RESULTS

Dasatinib did not change the frequency of osteonecrosis (p = .99) nor of arteriopathy (p = .36) in dexamethasone-treated mice when given at dosages that achieved clinically relevant steady-state dasatinib plasma concentrations of 53.1 ng/ml (95% CI: 43.5-57.3 ng/ml). These dasatinib exposures were not associated with increased dexamethasone plasma exposure in nonleukemia-bearing mice. These same dosages were not associated with any decrement in antileukemic efficacy of dexamethasone in a responsive BCR-ABL⁺ model of ALL.

CONCLUSIONS

Based on the results of our preclinical murine studies, we conclude that dasatinib is unlikely to increase the osteonecrotic effects of dexamethasone in ALL regimens.

Effects of zoledronic acid on osteonecrosis and acute lymphoblastic leukemia treatment efficacy in preclinical models

BACKGROUND

Osteonecrosis is a devastating side effect of acute lymphoblastic leukemia (ALL) therapy. Associations between bone density loss and osteonecrosis have sparked interest in using bisphosphonates to reduce this complication.

PROCEDURE

We assessed the impact of zoledronic acid (ZA) on the development of osteonecrosis in murine models when used either throughout therapy (continuous administration) or late in therapy after vascular lesions have developed but before osteonecrosis has occurred. Effects on bone density were measured using microcomputed tomography (μCT)-assessed tibial cortical thickness, while osteonecrosis was assessed histologically in the distal femur. Effects on antileukemic efficacy of chemotherapy were evaluated in both immunocompetent/syngeneic and patient-derived xenograft (PDX) models.

RESULTS

Continuous administration of ZA with chemotherapy prevented chemotherapy-associated bone loss (p < .001) and reduced osteonecrosis (p = .048). Late initiation of ZA diminished bone loss (p < .001) but had no impact on the development of osteonecrosis (p = .93). In the immunocompetent murine ALL model, mice treated with ZA and chemotherapy succumbed to leukemia sooner than mice treated with chemotherapy alone (p = .046). Analysis using PDX showed a nonsignificant decrease in survival with ZA (p = .17).

CONCLUSION

Our data indicate ZA may prevent osteonecrosis if begun with chemotherapy but showed no benefit when administered later in therapy. However, ZA may also reduce the antileukemic efficacy of chemotherapy.

Fenofibrate reduces osteonecrosis without affecting antileukemic efficacy in dexamethasone-treated mice

Recent clinical trials in children with acute lymphoblastic leukemia (ALL) indicate that severe hypertriglyceridemia (>1000 mg/dL) during therapy is associated with an increased frequency of symptomatic osteonecrosis. Interventions to lower triglycerides have been considered, but there have been no preclinical studies investigating the impact of lowering triglycerides on osteonecrosis risk, nor whether such interventions interfere with the antileukemic efficacy of ALL treatment. We utilized our clinically relevant mouse model of dexamethasoneinduced osteonecrosis to determine whether fenofibrate decreased osteonecrosis. To test whether fenofibrate affected the antileukemic efficacy of dexamethasone, we utilized a BCR-ABL+ model of ALL. Serum triglycerides were reduced by fenofibrate throughout the period of treatment, with the most pronounced, 4.5-fold, decrease at week 3 (P<1x10-6). Both frequency (33% vs. 74%, P=0.006) and severity (median necrosis score of 0 vs. 75; P=6x10-5) of osteonecrosis were reduced with fenofibrate. Fenofibrate had no impact on BCR-ABL+ ALL survival (P=0.65) nor on the antileukemic properties of dexamethasone (P=0.49). These data suggest that lowering triglycerides with fenofibrate reduces dexamethasone- induced osteonecrosis while maintaining antileukemic efficacy, and thus may be considered for clinical trials.

Idiopathic arteriopathy-induced focal osteonecrosis of the femoral head in a young dog

CASE DESCRIPTION

A 15-month-old 6.5-kg (14.3-lb) castrated male mixed-breed dog was evaluated because of a 4-month history of progressive intermittent non-weight-bearing lameness of the left pelvic limb.

CLINICAL FINDINGS

Orthogonal radiography of the hip joints revealed a 4-mm atypical radiolucent lesion on the distal caudomedial aspect of the left femoral head and a disproportionately large-diameter femoral medullary canal with a low canal flare index. Prolonged unresponsiveness to medical management and progressive enlargement of the lesion prompted the recommendation for total hip replacement (THR).

TREATMENT AND OUTCOME

THR was performed to restore pain-free function of the left pelvic limb and normal activity. A circular osteochondral flap was grossly evident on the femoral head. Histopathologic findings for this portion of the bone indicated an arteriopathy-induced focal subchondral osteonecrosis that had resulted in articular surface collapse. The noted idiopathic arteriopathy had disrupted the normal blood supply to the affected area. On reexamination and radiographic evaluation 13 months after THR, the dog appeared to have pain-free function of the affected limb and had returned to normal activity with no reported complications or problems.

CLINICAL RELEVANCE

To the authors' knowledge, this report represented the first description of arteriopathy-induced focal osteonecrosis of the caudomedial aspect of the femoral head and its successful treatment in a young dog. This type of lesion may more commonly be the cause of hip joint osteoarthritis in young dogs than previously recognized because establishing a definitive diagnosis requires early recognition and histologic evaluation before advanced degenerative changes develop that obscure the underlying etiology.

A tree shrew model for steroid-associated osteonecrosis

Osteonecrosis is a common human disease in orthopedics. It is difficult to treat, and half of patients may need artificial joint replacement, resulting in a considerable economic burden and a reduction in quality of life. Hormones are one of the major causes of osteonecrosis and high doses of corticosteroids are considered the most dangerous factor. Because of the complexity of treatment, we still need a better animal model that can be widely used in drug development and testing. Tree shrews are more closely related to primates than rodents. As such, we constructed a successful tree shrew model to establish and evaluate steroid-associated osteonecrosis (SAON). We found that low-dose lipopolysaccharide (LPS) combined with high-dose methylprednisolone (MPS) over 12 weeks could be used to establish a tree shrew model with femoral head necrosis. Serum biochemical and histological analyses showed that an ideal model was obtained. Thus, this work provides a useful animal model for the study of SAON and for the optimization of treatment methods.

Effects of hypoxia environment on osteonecrosis of the femoral head in Sprague-Dawley rats

INTRODUCTION

Osteonecrosis of the femoral head (ONFH) is a disease in which the blood supply of the femoral head is interrupted or damaged, resulting in joint dysfunction. Hypoxic environments increase the expression of EPO, VEGF, and HIF causes vascular proliferation and increases the blood supply. It also causes the organism to be in a state of hypercoagulability and increases thrombosis. Therefore, the purpose of this study was to explore the occurrence of ONFH after the use of glucocorticoids (GCs) under conditions of hypoxia tolerance for a long time.

MATERIALS AND METHODS

Sprague-Dawley rats were fed in a hypobaric hypoxic chamber at an altitude of 4000 m, the whole blood viscosity, and plasma viscosity were determined to analyze the blood flow and hemagglutination. Western blotting, polymerase chain reaction, and immunohistochemistry were used to detect EPO, VEGF, CD31, and osteogenesis related proteins. Femoral head angiography was used to examine the local blood supply and micro-CT scanning was used to detect the structure of the bone trabecula.

RESULTS

Under hypoxic environments, the expression of EPO and VEGF increased, which increased the local blood supply of the femoral head, but due to more severe thrombosis, the local blood supply of the femoral head decreased.

CONCLUSIONS

Hypoxic environments can aggravate ONFH in SD rats; this aggravation may be related to the hypercoagulable state of the blood. We suggest that long-term hypoxia should be regarded as one of the risk factors of ONFH and we need to conduct a more extensive epidemiological investigation on the occurrence of ONFH in hypoxic populations.

Pharmacogenomics and ALL treatment: How to optimize therapy

Inherited genetic variations may alter drug sensitivity in patients with acute lymphoblastic leukemia, predisposing to adverse treatment side effects. In this review, we discuss evidence from children and young adults with acute lymphoblastic leukemia to review the available pharmacogenomic data with an emphasis on clinically actionable and emerging discoveries, for example, genetic variants in thiopurine methyltransferase and NUDT15 that alter 6-mercaptopurine dosing. We also highlight the need for ongoing pharmacogenomic research to validate the significance of recent findings. Further research in young adults, as well as with novel therapeutics, is needed to provide optimal therapy in future trials.

Implementation of Pharmacogenetics to Individualize Treatment Regimens for Children with Acute Lymphoblastic Leukemia

Despite major advances in the management and high cure rates of childhood acute lymphoblastic leukemia (ALL), patients still suffer from many drug-induced toxicities, sometimes necessitating dose reduction, or halting of cytotoxic drugs with a secondary risk of disease relapse. In addition, investigators have noted significant inter-individual variability in drug toxicities and disease outcomes, hence the role of pharmacogenetics (PGx) in elucidating genetic polymorphisms in candidate genes for the optimization of disease management. In this review, we present the PGx data in association with main toxicities seen in children treated for ALL in addition to efficacy, with a focus on the most plausible germline PGx variants. We then follow with a summary of the highest evidence drug-gene annotations with suggestions to move forward in implementing preemptive PGx for the individualization of treatment regimens for children with ALL.

Whole-joint magnetic resonance imaging to assess osteonecrosis in pediatric patients with acute lymphoblastic lymphoma

BACKGROUND

Osteonecrosis is a debilitating complication in children and adolescents with acute lymphoblastic leukemia or acute lymphoblastic lymphoma (LLy). An objective screening test to identify patients at risk for symptomatic, extensive joint involvement will help manage osteonecrosis.

METHODS

We performed a prospective, longitudinal pilot study with whole-joint magnetic resonance imaging (MRI) of shoulders, elbows, hips, knees, ankles, and hindfeet to evaluate the incidence and timing of osteonecrosis involving multiple joints in 15 patients with LLy aged 9-21 years at diagnosis.

RESULTS

Osteonecrosis affecting ≥30% of the epiphysis occurred in eight of 15 patients, with a high prevalence in hips (12 of 26 examined [46%]) and knees (10 of 26 [38%]) post reinduction I and in shoulders (seven of 20 [35%]) post reinduction II. Most osteonecrotic hips and knees with ≥30% epiphyseal involvement became symptomatic and/or underwent surgery (100% and 82%, respectively). All eight patients with ≥30% epiphyseal involvement had multijoint involvement. Seven of these patients had hip or knee osteonecrosis by the end of remission induction, and only these patients developed osteonecrosis that became symptomatic and/or underwent surgery in their hips, knees, shoulders, ankles, and/or feet; all of these joints were associated with epiphyseal abnormalities on post reinduction I imaging.

CONCLUSIONS

MRI screening in adolescent patients with LLy revealed osteonecrosis in multiple joints. Initial screening with hip and knee MRI at the end of induction may identify susceptible patients who could benefit from referrals to subspecialties, more extensive follow-up imaging of other joints, and early medical and surgical interventions.

Long-Term Functional Outcomes Among Childhood Survivors of Cancer Who Have a History of Osteonecrosis

BACKGROUND

Glucocorticoids used to treat childhood leukemia and lymphoma can result in osteonecrosis, leading to physical dysfunction and pain. Improving survival rates warrants research into long-term outcomes among this population.

OBJECTIVE

The objective of this study was to compare the physical function and quality of life (QOL) of survivors of childhood cancer who had an osteonecrosis history with that of survivors who had no osteonecrosis history and with that of people who were healthy (controls).

DESIGN

This was a cross-sectional study.

METHODS

This study included St Jude Lifetime Cohort Study participants who were ≥ 10 years from the diagnosis of childhood leukemia or lymphoma and ≥ 18 years old; 135 had osteonecrosis (52.5% men; mean age = 27.7 [SD = 6.08] years) and 1560 had no osteonecrosis history (52.4% men; mean age = 33.3 [SD = 8.54] years). This study also included 272 people who were from the community and who were healthy (community controls) (47.7% men; mean age = 35.1 [SD = 10.46] years). The participants completed functional assessments and questionnaires about QOL.

RESULTS

Survivors with osteonecrosis scored lower than other survivors and controls for dorsiflexion strength (mean score = 16.50 [SD = 7.91] vs 24.17 [SD = 8.61] N·m/kg) and scored lower than controls for flexibility with the sit-and-reach test (20.61 [SD = 9.70] vs 23.96 [SD = 10.73] cm), function on the Physical Performance Test (mean score = 22.73 [SD = 2.05] vs 23.58 [SD = 0.88]), and mobility on the Timed "Up & Go" Test (5.66 [SD = 2.25] vs 5.12 [SD = 1.28] seconds). Survivors with hip osteonecrosis requiring surgery scored lower than survivors without osteonecrosis for dorsiflexion strength (13.75 [SD = 8.82] vs 18.48 [SD = 9.04] N·m/kg), flexibility (15.79 [SD = 8.93] vs 20.37 [SD = 10.14] cm), and endurance on the 6-minute walk test (523.50 [SD = 103.00] vs 572.10 [SD = 102.40] m).

LIMITATIONS

Because some eligible survivors declined to participate, possible selection bias was a limitation of this study.

CONCLUSIONS

Survivors of childhood leukemia and lymphoma with and without osteonecrosis demonstrated impaired physical performance and reported reduced QOL compared with controls, with those requiring surgery for osteonecrosis most at risk for impairments. It may be beneficial to provide strengthening, flexibility, and endurance interventions for patients who have pediatric cancer and osteonecrosis for long-term function.

Nonproliferative and Proliferative Lesions of the Rat and Mouse Hematolymphoid System

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative changes in rats and mice. The purpose of this publication is to provide a standardized nomenclature for classifying changes observed in the hematolymphoid organs, including the bone marrow, thymus, spleen, lymph nodes, mucosa-associated lymphoid tissues, and other lymphoid tissues (serosa-associated lymphoid clusters and tertiary lymphoid structures) with color photomicrographs illustrating examples of the lesions. Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions as well as lesions induced by exposure to test materials. The nomenclature for these organs is divided into 3 terminologies: descriptive, conventional, and enhanced. Three terms are listed for each diagnosis. The rationale for this approach and guidance for its application to toxicologic pathology are described in detail below.

Somatic and germline genomics in paediatric acute lymphoblastic leukaemia

Advances in genomic research and risk-directed therapy have led to improvements in the long-term survival and quality of life outcomes of patients with childhood acute lymphoblastic leukaemia (ALL). The application of next-generation sequencing technologies, especially transcriptome sequencing, has resulted in the identification of novel molecular subtypes of ALL with prognostic and therapeutic implications, as well as cooperative mutations that account for much of the heterogeneity in clinical responses observed among patients with specific ALL subtypes. In addition, germline genetic variants have been shown to influence the risk of developing ALL and/or the responses of non-malignant and leukaemia cells to therapy; shared pathways for drug activation and metabolism are implicated in treatment-related toxicity and drug sensitivity or resistance, depending on whether the genetic changes are germline, somatic or both. Indeed, although once considered a non-hereditary disease, genomic investigations of familial and sporadic ALL have revealed a growing number of genetic alterations or conditions that predispose individuals to the development of ALL and treatment-related second cancers. The identification of these genetic alterations holds the potential to direct genetic counselling, testing and possibly monitoring for the early detection of ALL and other cancers. Herein, we review these advances in our understanding of the genomic landscape of childhood ALL and their clinical implications.

Bloodstream infections exacerbate incidence and severity of symptomatic glucocorticoid-induced osteonecrosis

BACKGROUND

Osteonecrosis is a common toxicity associated with glucocorticoid (e.g., dexamethasone and prednisone) treatment of children with acute lymphoblastic leukemia (ALL), but risk factors are incompletely defined. Infections are also a common complication of ALL therapy. Lipopolysaccharide (LPS) is used experimentally to mimic infection-related systemic effects. To our knowledge, the contribution of systemic infections to the risk of glucocorticoid-induced osteonecrosis has not been investigated.

PROCEDURE

Patients with ALL on St. Jude Total Therapy XV (n = 365) were assessed for documented bacteremia prior to development of osteonecrosis, which was confirmed by MRI, and graded using the National Cancer Institute's Common Terminology for Adverse Events (version 3.0). In a preclinical model, Balb/cJ mice treated with dexamethasone plus or minus LPS were assessed for frequency and severity of osteonecrosis and arteriopathy.

RESULTS

We found that patients with ALL who experienced bacteremia had a higher frequency of symptomatic osteonecrosis (≥grade 2) than those who did not (OR: 1.88; 95% CI, 1.03-3.41, P = 0.038). LPS exacerbated experimental dexamethasone-induced osteonecrosis. Mice treated with dexamethasone plus LPS had a higher incidence of osteonecrosis (P = 0.00086) and arteriopathy (P = 0.0047) than did those treated with dexamethasone alone, and the severity of osteonecrosis (P = 0.00045) and arteriopathy (P = 0.0048) was also more pronounced with the addition of LPS treatment. The increase in osteonecrosis was not explained by any alteration of dexamethasone pharmacokinetics by LPS.

CONCLUSIONS

These data identify systemic infection during ALL therapy as a novel risk factor in the development of glucocorticoid-induced osteonecrosis.

Asparaginase combined with discontinuous dexamethasone improves antileukemic efficacy without increasing osteonecrosis in preclinical models

Introduction

Combination therapy for acute lymphoblastic leukemia (ALL) is highly effective but results in significant toxicity including osteonecrosis. Asparaginase is known to potentiate both the antileukemic and osteonecrosis-inducing effects of dexamethasone. The schedule of dexamethasone alters osteonecrosis risk. However, the effects of the interaction with asparaginase are unknown when dexamethasone is given on a discontinuous schedule.

Methods

Using the murine model of osteonecrosis, we compared the frequency of osteonecrosis in mice receiving discontinuous dexamethasone (3.5 days/ week) with mice receiving asparaginase and discontinuous dexamethasone. We then tested the effect on antileukemic efficacy using six pediatric ALL xenografts.

Results

The addition of asparaginase to discontinuous dexamethasone did not alter the rate of osteonecrosis compared to dexamethasone alone (7/35 in dexamethasone with asparaginase combination vs. 10/36 in dexamethasone alone, p = 0.62) despite increasing steady-state plasma dexamethasone levels (103.9 nM vs. 33.4 nM, p = 9.2x10^-7). Combination therapy with asparaginase and dexamethasone demonstrated synergistic antileukemic effects across all six xenografts studied.

Conclusions

When discontinuous dexamethasone was given, its anti-leukemic activity synergized with asparaginase but the osteonecrosis-worsening effects of asparaginase (above dexamethasone alone) were not observed. Thus, there is a favorable drug interaction (unchanged toxicity, synergistic efficacy) between discontinuous dexamethasone and asparaginase.

Association of TIMP4 gene variants with steroid-induced osteonecrosis of the femoral head in the population of northern China

Background

In clinical treatment, the use of steroid hormones is an important etiological factor of non-traumatic osteonecrosis of the femoral head (ONFH) risk. As an endogenous inhibitor of matrix metalloproteinases (MMPs) in the extracellular matrix, the expression of tissue inhibitors of metalloprotease-4 (TIMP4) plays an essential role in cartilage and bone tissue damage and remodeling, vasculitis formation, intravascular thrombosis, and lipid metabolism.

Methods

This study aimed to detect the association between TIMP4 polymorphism and steroid-induced ONFH. We genotyped seven single-nucleotide polymorphisms (SNPs) in TIMP4 genes and analyzed the association with steroid-induced ONFH from 286 steroid-induced ONFH patients and 309 normal individuals.

Results

We performed allelic model analysis and found that the minor alleles of five SNPs (rs99365, rs308952, rs3817004, rs2279750, and rs3755724) were associated with decreased steroid-induced ONFH (p = 0.02, p = 0.03, p = 0.04, p = 0.01, p = 0.04, respectively). rs2279750 showed a significant association with decreased risk of steroid-induced ONFH in the Dominant and Log-additive models (p = 0.042, p = 0.028, respectively), and rs9935, rs30892, and rs3817004 were associated with decreased risk in the Log-additive model (p = 0.038, p = 0.044, p = 0.042, respectively). In further stratification analysis, TIMP4 gene variants showed a significant association with steroid-induced ONFH in gender under the genotypes. Haplotype analysis also revealed that “TCAGAC” and “CCGGAA” sequences have protective effect on steroid-induced ONFH.

Conclusion

Our results indicate that five TIMP4 SNPs (rs99365, rs308952, rs3817004rs2279750, and rs3755724) are significantly associated with decreased risk of steroid-induced ONFH in the population of northern China.

Prevalence of glucocorticoid induced osteonecrosis in the mouse is not affected by treatments that maintain bone vascularity

Objective

Determine if LLP2A-Ale or PTH (1–34) affects the prevalence of glucocorticoid-induced osteonecrosis (ON) in a mouse model.

Methods

Eight-week-old young adult male BALB/cJ mice were weight-randomized into Control (Con), glucocorticoid (GC)-only, or concurrent treatments with GC and LLP2A-Ale (250 μg/kg or 500 μg/kg, IV, Days 1, 14, 28) or parathyroid hormone hPTH (1–34) (40 μg/kg, 5×/week). Mice were necropsied after 45 days for qualitative evaluation of prevalent ON and quantitative evaluation of vascularity in the distal femoral epiphysis (DFE); and quantitative evaluation of bone mass, microarchitecture, and strength in the distal femoral metaphysis and lumbar vertebral body.

Results

The prevalence of ON was 14% in the Con group and 36% in the GC-only group (P = 0.07). The prevalence of ON did not differ among GC-only, GC + LLP2A-Ale, and GC + PTH groups. GC-only mice had significantly lower trabecular and cortical bone strength than Con, while GC + LLP2A-Ale (500 μg/kg) and GC + PTH (1–34) groups had significantly greater trabecular bone strength than the GC-only group. GC + LLP2A-Ale (250 μg/kg and 500 μg/kg) and GC + PTH had significantly higher trabecular bone volume than GC-only mice at the vertebrae, distal femoral epiphyses and distal femoral metaphyses. DFE vascularity was lower in GC-only mice than in all other groups.

Conclusion

Neither LLP2A-Ale nor hPTH (1–34) reduced the prevalence of GC-induced ON, compared to GC-only mice. However, GC-treated mice given LLP2A-Ale or hPTH (1–34) had better bone mass, microarchitecture, and strength in trabecular-rich regions, and higher levels of vascularity than GC-only mice.

Strain-specific differences in the development of bone loss and incidence of osteonecrosis following glucocorticoid treatment in two different mouse strains

Objective

Glucocorticoids (GCs) are commonly prescribed as treatment for chronic inflammatory diseases. Prolonged use of GCs is a common cause of atraumatic osteonecrosis (ON) and secondary osteoporosis. Currently, there is no effective treatment for this disease; therefore, a reliable animal model would be useful to study both the pathology and novel treatment strategies for patients with the disease. The aim of this study was to establish a validated, reproducible model of GC-induced ON and bone loss in two different mouse strains (BALB/c and C57BL/6).

Methods

Seven-week-old male BALB/c (n = 32) and male C57BL/6 mice (n = 32) were randomised into placebo or GC groups and treated with daily 4 mg/L oral dexamethasone in drinking water for 90 days. Study outcome measures included histologic assessment of ON of the distal femur, bone mass and mechanical strength of tibia and lumbar vertebral body, osteoclast number, biochemical measure of bone formation and bone marrow fat quantitation.

Results

GC-induced ON lesions were observed in the distal femur in 47% of the male BALB/c mice and 25% of the male C57BL/6 mice. GC treatment decreased the trabecular bone volume and serum pro-collagen type 1N-protease (P1NP) in BALB/c mice compared with the placebo (p < 0.05) and reduced tibial bone strength in both BALB/c and C57BL/6 mice. GC-treated BALB/c mice had significantly greater marrow fat levels compared to the placebo group.

Conclusion

GC-induced ON was more prevalent in the male BALB/c mice compared to the male C57BL/6 mice. GC treatment significantly reduced bone mass, bone formation measured by P1NP, bone strength and increased marrow fat levels in male BALB/c mice. Therefore, the use of male BALB/c mice strain is recommended for both diagnostic and therapeutic studies for the prevention and treatment of ON and bone loss following prolonged treatment with GCs.

The Translational Potential of this Article

GCs are commonly used to treat patients with various chronic inflammatory diseases, and this is associated with both the development of ON and bone loss. Our study confirmed that the BALB/c mouse strain treated for 90 days with GC may be useful for developing novel treatments for ON.

Genetics of pleiotropic effects of dexamethasone

OBJECTIVES

Glucocorticoids such as dexamethasone have pleiotropic effects, including desired antileukemic, anti-inflammatory, or immunosuppressive effects, and undesired metabolic or toxic effects. The most serious adverse effects of dexamethasone among patients with acute lymphoblastic leukemia are osteonecrosis and thrombosis. To identify inherited genomic variation involved in these severe adverse effects, we carried out genome-wide association studies (GWAS) by analyzing 14 pleiotropic glucocorticoid phenotypes in 391 patients with acute lymphoblastic leukemia.

PATIENTS AND METHODS

We used the Projection Onto the Most Interesting Statistical Evidence integrative analysis technique to identify genetic variants associated with pleiotropic dexamethasone phenotypes, stratifying for age, sex, race, and treatment, and compared the results with conventional single-phenotype GWAS. The phenotypes were osteonecrosis, central nervous system toxicity, hyperglycemia, hypokalemia, thrombosis, dexamethasone exposure, BMI, growth trajectory, and levels of cortisol, albumin, and asparaginase antibodies, and changes in cholesterol, triglycerides, and low-density lipoproteins after dexamethasone.

RESULTS

The integrative analysis identified more pleiotropic single nucleotide polymorphism variants (P=1.46×10(-215), and these variants were more likely to be in gene-regulatory regions (P=1.22×10(-6)) than traditional single-phenotype GWAS. The integrative analysis yielded genomic variants (rs2243057 and rs6453253) in F2RL1, a receptor that functions in hemostasis, thrombosis, and inflammation, which were associated with pleiotropic effects, including osteonecrosis and thrombosis, and were in regulatory gene regions.

CONCLUSION

The integrative pleiotropic analysis identified risk variants for osteonecrosis and thrombosis not identified by single-phenotype analysis that may have importance for patients with underlying sensitivity to multiple dexamethasone adverse effects.

Musculoskeletal complications following total body irradiation in hematopoietic stem cell transplant patients

Total body irradiation (TBI) is commonly used in conditioning regimens for allogeneic hematopoietic stem cell transplantation (HSCT) to treat benign and malignant disease. Though life-saving, these therapies place patients at risk for important side effects, including musculoskeletal complications such as short stature, osteonecrosis, slipped capital femoral epiphysis, and the development of benign and malignant bone tumors. With an increasing number of HSCT survivors, there is a growing need for awareness of the musculoskeletal complications of HSCT and TBI.

Osteonecrosis in children and adolescents with acute lymphoblastic leukemia: a therapeutic challenge

Osteonecrosis (ON) represents one of the most common and debilitating sequelae of antileukemic treatment in children and adolescents with acute lymphoblastic leukemia (ALL). Systematic screening strategies can focus on early detection and intervention to prevent ON from progressing to stages associated with pain and functional impairment. These strategies hold promise for reducing ON-associated morbidity without the risk of impairing leukemia control. Herein, we critically reviewed clinical data on pharmacological, nonpharmacological/nonsurgical, and surgical (including cellular) treatment options for ON, which are covered in the literature and/or are conceivable based on the supposed underlying ON pathophysiology. Prevention of ON progression is of paramount importance, and attempts seem to be more effective in early (precollapse) disease status than in late-stage (collapse) ON. Based on the results of ongoing prospective magnetic resonance imaging screening studies, which will hopefully identify those patients with a high risk of ON progression and debilitating sequelae, prospective interventional studies are urgently needed. Although there is still a lack of high-quality studies, based on currently available data, core decompression surgery combined with cellular therapies (eg, employing mesenchymal stem cells) appears most promising for preventing joint infraction in children at high risk of developing late-stage ON.

A Novel Hybrid Compound LLP2A-Ale Both Prevented and Rescued the Osteoporotic Phenotype in a Mouse Model of Glucocorticoid-Induced Osteoporosis

Prolonged glucocorticoid (GC) administration causes secondary osteoporosis (GIOP) and non-traumatic osteonecrosis. LLP2A-Ale is a novel bone-seeking compound that recruits mesenchymal stem cells to the bone surface, stimulates bone formation, and increases bone mass. The purpose of this study was to determine if treatment with LLP2A-Ale alone or in combination with parathyroid hormone (PTH) could prevent or treat GIOP in a mouse model. Four-month-old male Swiss-Webster mice were randomized to a prevention study with placebo, GC (day 1-28), and GC + LLP2A-Ale (IV, day 1) or a treatment study with placebo, GC (days 1-56), GC + LLP2A-Ale (IV, day 28), GC + PTH, and GC + LLP2A-Ale + PTH (days 28-56). Mice were killed on day 28 (prevention study) or on day 56 (treatment study). The study endpoints included bone mass, bone strength, serum markers of bone turnover (P1NP and CTX-I) and angiogenesis (VEGF-A), surface-based bone turnover, and blood vessel density. LLP2A-Ale prevented GC-induced bone loss and increased mechanical strength in the vertebral body (days 28 and 56) and femur (day 56). LLP2A-Ale, PTH, and LLP2A-Ale + PTH treatment significantly increased the mineralizing surface, bone formation rate, mineral apposition rate, double-labeled surface, and serum P1NP level on day 56. LLP2A-Ale and PTH treatment increased femoral blood vessel density and LLP2A-Ale increased serum VEGF-A on day 28. Therefore, LLP2A-Ale monotherapy could be a potential option to both prevent and treat GC-induced osteoporosis and bone fragility.

Osteonecrosis in children with acute lymphoblastic leukemia

The morbidity and toxicity associated with current intensive treatment protocols for acute lymphoblastic leukemia in childhood become even more important as the vast majority of children can be cured and become long-term survivors. Osteonecrosis is one of the most common therapy-related and debilitating side effects of anti-leukemic treatment and can adversely affect long-term quality of life. Incidence and risk factors vary substantially between study groups and therapeutic regimens. We therefore analyzed 22 clinical trials of childhood acute lymphoblastic leukemia in terms of osteonecrosis incidence and risk factors. Adolescent age is the most significant risk factor, with patients >10 years old at the highest risk. Uncritical modification or even significant reduction of glucocorticoid dosage cannot be recommended at this stage. A novel and innovative approach to reduce osteonecrosis-associated morbidity might be systematic early screening for osteonecrosis by serial magnetic resonance images. However, discriminating patients at risk of functional impairment and debilitating progressive joint disease from asymptomatic patients still remains challenging.

Osteonecrosis detected by whole body magnetic resonance in patients with Hodgkin Lymphoma treated by BEACOPP

OBJECTIVES

The purpose of our retrospective review of prospectively acquired Whole Body Magnetic Resonance (WB-MRI) scans was to assess the incidence of osteonecrosis in patients who received different chemotherapies.

METHODS

We evaluated the WB-MRI scans performed on 42 patients with Hodgkin Lymphoma treated by three chemotherapy regimens (6ABVD, 2ABVD + 4BEACOPP, 2ABVD + 8BEACOPP), excluding patients with the main risk factors for osteonecrosis.

RESULTS

Six out of seven patients (86 %) who received eight BEACOPP and one out of five patients (20 %) treated by four BEACOPP presented osteonecrosis, with a statistically significant difference of frequency between the two groups of patients (p < 0.05); no injury has been reported in patients treated by only ABVD. Among a total of 48 osteonecrotic lesions observed, 48 % were detected in the knee; multifocal osteonecrosis were detected in six out of seven patients (86 %).

CONCLUSIONS

The development of osteonecrosis is strictly related to the chemotherapy protocol adopted and the number of cycles received, with a strong correlation between the dose of corticosteroids included in the BEACOPP scheme and this complication. WB-MRI can be considered as a helpful tool that allows detecting earlier osteonecrotic lesions in patients treated with corticosteroids.

KEY POINTS

• Osteonecrosis is a possible complication of patients with Lymphoma treated by chemotherapy. • Osteonecrosis is related to the corticosteroids included within the BEACOPP protocol. • WB-MRI allows detecting osteonecrotic lesions in patients treated with corticosteroids.

Asparaginase Potentiates Glucocorticoid-Induced Osteonecrosis in a Mouse Model

Osteonecrosis is a common dose-limiting toxicity of glucocorticoids. Data from clinical trials suggest that other medications can increase the risk of glucocorticoid-induced osteonecrosis. Here we utilized a mouse model to study the effect of asparaginase treatment on dexamethasone-induced osteonecrosis. Mice receiving asparaginase along with dexamethasone had a higher rate of osteonecrosis than those receiving only dexamethasone after 6 weeks of treatment (44% vs. 10%, P = 0.006). Similarly, epiphyseal arteriopathy, which we have shown to be an initiating event for osteonecrosis, was observed in 58% of mice receiving asparaginase and dexamethasone compared to 17% of mice receiving dexamethasone only (P = 0.007). As in the clinic, greater exposure to asparaginase was associated with greater plasma exposure to dexamethasone (P = 0.0001). This model also recapitulated other clinical risk factors for osteonecrosis, including age at start of treatment, and association with the systemic exposure to dexamethasone (P = 0.027) and asparaginase (P = 0.036). We conclude that asparaginase can potentiate the osteonecrotic effect of glucocorticoids.

Genetic risk factors for the development of osteonecrosis in children under age 10 treated for acute lymphoblastic leukemia

Osteonecrosis is a dose-limiting toxicity in the treatment of pediatric acute lymphoblastic leukemia (ALL). Prior studies on the genetics of osteonecrosis have focused on patients ≥10 years of age, leaving the genetic risk factors for the larger group of children <10 years incompletely understood. Here, we perform the first evaluation of genetic risk factors for osteonecrosis in children <10 years. The discovery cohort comprised 82 cases of osteonecrosis and 287 controls treated on Children's Oncology Group (COG) standard-risk ALL protocol AALL0331 (NCT00103285, https://clinicaltrials.gov/ct2/show/NCT00103285), with results tested for replication in 817 children <10 years treated on COG protocol AALL0232 (NCT00075725, https://clinicaltrials.gov/ct2/show/NCT00075725). The top replicated single nucleotide polymorphisms (SNPs) were near bone morphogenic protein 7 [BMP7: rs75161997, P = 5.34 × 10(-8) (odds ratio [OR] 15.0) and P = .0498 (OR 8.44) in the discovery and replication cohorts, respectively] and PROX1-antisense RNA1 (PROX1-AS1: rs1891059, P = 2.28 × 10(-7) [OR 6.48] and P = .0077 [OR 3.78] for the discovery and replication cohorts, respectively). The top replicated nonsynonymous SNP, rs34144324, was in a glutamate receptor gene (GRID2, P = 8.65 × 10(-6) [OR 3.46] and P = .0136 [OR 10.8] in the discovery and replication cohorts, respectively). In a meta-analysis, the BMP7 and PROX1-AS1 variants (rs75161997 and rs1891059, respectively) met the significance threshold of <5 × 10(-8). Top replicated SNPs were enriched in enhancers active in mesenchymal stem cells, and analysis of annotated genes demonstrated enrichment in glutamate receptor and adipogenesis pathways. These data may provide new insights into the pathophysiology of osteonecrosis.

Genetics of glucocorticoid-associated osteonecrosis in children with acute lymphoblastic leukemia

Glucocorticoids are important therapy for acute lymphoblastic leukemia (ALL) and their major adverse effect is osteonecrosis. Our goal was to identify genetic and nongenetic risk factors for osteonecrosis. We performed a genome-wide association study of single nucleotide polymorphisms (SNPs) in a discovery cohort comprising 2285 children with ALL, treated on the Children's Oncology Group AALL0232 protocol (NCT00075725), adjusting for covariates. The minor allele at SNP rs10989692 (near the glutamate receptor GRIN3A locus) was associated with osteonecrosis (hazard ratio = 2.03; P = 3.59 × 10(-7)). The association was supported by 2 replication cohorts, including 361 children with ALL on St. Jude's Total XV protocol (NCT00137111) and 309 non-ALL patients from Vanderbilt University's BioVU repository treated with glucocorticoids (odds ratio [OR] = 1.87 and 2.26; P = .063 and .0074, respectively). In a meta-analysis, rs10989692 was also highest ranked (P = 2.68 × 10(-8)), and the glutamate pathway was the top ranked pathway (P = 9.8 × 10(-4)). Osteonecrosis-associated glutamate receptor variants were also associated with other vascular phenotypes including cerebral ischemia (OR = 1.64; P = 2.5 × 10(-3)), and arterial embolism and thrombosis (OR = 1.88; P = 4.2 × 10(-3)). In conclusion, osteonecrosis was associated with inherited variations near glutamate receptor genes. Further understanding this association may allow interventions to decrease osteonecrosis. These trials are registered at www.clinicaltrials.gov as #NCT00075725 and #NCT00137111.

Antileukemic Efficacy of Continuous vs Discontinuous Dexamethasone in Murine Models of Acute Lymphoblastic Leukemia

Osteonecrosis is one of the most common, serious, toxicities resulting from the treatment of acute lymphoblastic leukemia. In recent years, pediatric acute lymphoblastic leukemia clinical trials have used discontinuous rather than continuous dosing of dexamethasone in an effort to reduce the incidence of osteonecrosis. However, it is not known whether discontinuous dosing would compromise antileukemic efficacy of glucocorticoids. Therefore, we tested the efficacy of discontinuous dexamethasone against continuous dexamethasone in murine models bearing human acute lymphoblastic leukemia xenografts (n = 8 patient samples) or murine BCR-ABL+ acute lymphoblastic leukemia. Plasma dexamethasone concentrations (7.9 to 212 nM) were similar to those achieved in children with acute lymphoblastic leukemia using conventional dosages. The median leukemia-free survival ranged from 16 to 59 days; dexamethasone prolonged survival from a median of 4 to 129 days in all seven dexamethasone-sensitive acute lymphoblastic leukemias. In the majority of cases (7 of 8 xenografts and the murine BCR-ABL model) we demonstrated equal efficacy of the two dexamethasone dosing regimens; whereas for one acute lymphoblastic leukemia sample, the discontinuous regimen yielded inferior antileukemic efficacy (log-rank p = 0.002). Our results support the clinical practice of using discontinuous rather than continuous dexamethasone dosing in patients with acute lymphoblastic leukemia.

Steroid-associated osteonecrosis: Epidemiology, pathophysiology, animal model, prevention, and potential treatments (an overview)

Steroid-associated osteonecrosis (SAON) is a common orthopaedic problem caused by administration of corticosteroids prescribed for many nonorthopaedic medical conditions. We summarised different pathophysiologies of SAON which have adverse effects on multiple systems such as bone marrow stem cells (BMSCs) pool, bone matrix, cell apoptosis, lipid metabolism, and angiogenesis. Different animal models were introduced to mimic the pathophysiology of SAON and for testing the efficacy of both prevention and treatment effects of various chemical drugs, biological, and physical therapies. According to the classification of SAON, several prevention and treatment methods are applied at the different stages of SAON. For the current period, Chinese herbs may also have the potential to prevent the occurrence of SAON. In the future, genetic analysis might also be helpful to effectively predict the development of ON and provide information for personalised prevention and treatment of patients with SAON.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Immune response associated with Toll-like receptor 4 signaling pathway leads to steroid-induced femoral head osteonecrosis

Background

Femoral head osteonecrosis is frequently observed in patients treated with excessive corticosteroids. The objective of the current study was to establish a rat model to investigate the disruption of immune response in steroid-induced femoral head osteonecrosis via Toll-like receptor 4 (TLR4) signaling pathway.

Methods

Male SD rats were divided into the treatment group (group A) and the model group (group B) consisting of 24 rats each, and were injected intramuscularly with 20 mg/kg methylprednisolone (MP) for 8 weeks, once a week. The rats in group A were injected intravenously with 7.5 mg/kg TAK242 before each MP administration. A control group (group N) consisted of 12 rats were received saline injection. All animals were sacrificed 8, 10 and 12 weeks from the first MP injection, respectively. Histopathological analysis was performed and the concentration of tartrate-resistant acid phosphatase (TRAP) in serum was tested. The signaling molecules including TLR4, MyD88, NF-κB p65 and MCP-1 were detected by immunohistochemistry, quantitative real-time PCR and Western blot.

Results

Femoral head osteonecrosis was observed in the model rats, and the concentration of TRAP and positive staining of all signaling molecules increased significantly in group B compared with that in group A and group N. Compare with the control group, the mRNA expressions and protein levels of all signaling molecules were enhanced significantly in group B, but no significant in group A.

Conclusions

Corticosteroids can induce femoral head osteonecrosis by disturbing the immune response via TLR4 signaling pathway. These findings suggest that the disruption of immune response play a role in the pathogenesis of osteonecrosis.