Risk of venous thromboembolism and major bleeding in the clinical course of osteosarcoma and Ewing sarcoma.

BACKGROUND: Patients with osteosarcoma (OS) and Ewing sarcoma (ES) are considered to have a high venous thromboembolism (VTE) risk, although the exact incidence and prognostic impact are under-researched in general as well as in relevant age groups. AIMS: To study the impact of VTE and major bleeding (MB) in OS and ES patients, subdivided in children, Adolescents Young Adults (AYAs; aged 18-39) and older adults. METHODS: Retrospective single-center chart review in 519 OS and 165 ES patients treated between 1980 and 2018. Patients were followed from sarcoma diagnosis until an outcome of interest (VTE, MB) or death occurred. Cumulative incidences were estimated with death as competing risk. Cox models were used to determine prognostic impact. RESULTS: Five-year cumulative incidences of VTE were 12 % (95%CI 9.1-15) for OS and 6.7 % (95%CI 3.5-11) for ES patients, mostly happening in patients ≥18 years; the most frequent VTE presentation was catheter-related upper-extremity thrombosis (OS: 18/65, ES: 7/11). Five-year cumulative incidences for MB were 5.8 % (95%CI 4.0-8.1) in OS and 5.4 % (95%CI 2.5-9.8) in ES patients. 192 OS and 77 ES AYAs were included, who faced similar VTE and MB incidences as older adults. In OS, VTE and MB were both associated with mortality (adjusted HRs 2.0 [95%CI 1.4-2.9] and 2.4 [95%CI 1.4-4.0], respectively), whereas in ES this association was only present for MB (aHR 3.4 [95%CI 1.2-9.6]). CONCLUSIONS: VTE is a frequent complication in adult OS and to a lesser extent in ES patients, while the rate of MB was comparably high in both sarcoma types.

Bisphenol A interacts with DLGAP5 and regulates IL-6/JAK2/STAT3 signaling pathway to promote tumorigenesis and progression of osteosarcoma.

OBJECTIVE: It has been suggested that Bisphenol A (BPA), a high-production-volume industrial chemical, can accelerate the development of various type of cancers. However, the effect of BPA on osteosarcoma and the underlying mechanisms are yet to be established. Therefore, in this study we tried to explore the carcinogenic effects of BPA on osteosarcoma and the underlying mechanism. METHODS: SaOs-2 cancer cell line was used to treat with BPA at the doses of 0.1, 1, 10 µM DGLAP5 knockdown and overexpression methods were constructed by using adenovirus mediated transfection, and the functional analysis of DGLAP5 was investigated to evaluate the carcinogenic effect of BPA on osteosarcoma through DLGAP5. Xenograft and metastatic mouse model were used to evaluate in vivo experiments. RESULTS: In this study, BPA at 10 µM promoted the proliferation, migration and invasion in vitro, and accelerate the progression and metastasis in vivo. Also, exposure to BPA was associated with poor survival of osteosarcoma in mice. In addition, we observed that BPA at 10 µM significantly increased the expression of DGLAP5 in osteosarcoma. Silencing DGLAP5 could reverse the effect of BPA on proliferation, migration and invasion. Mechanically, BPA promoted IL-6, JAK2, and STAT3 expression and promoted tumor progression in an IL-6-dependent manner through up-regulation of DLGAP5. CONCLUSION: Our findings demonstrated that BPA could promote the proliferation, migration, invasion of osteosarcoma cells and related to poor survival in a mouse model. DLGAP5 is one of the most critical targets of BPA to act as a carcinogen through IL-6/JAK2/STAT3 signaling pathway.

Postoperative Analgesia and Palliative Care of Peng Block for Terminal Osteosarcoma.

Palliative care involves patients with a high incidence of chronic pain and inadequate treatment related to opioid abuse. In terminal patients, the side effects of opioids may result in lower quality of life due to their deleterious immunosuppression and gastrointestinal effects. In our routine clinical practice, we consider the ultrasound-guided PENG block as a palliative analgesic technique to improve end-of-life care to terminal patients.

Clinical Application of Artificial Intelligence: Auto-Discerning the Effectiveness of Lidocaine Concentration Levels in Osteosarcoma Femoral Tumor Segment Resection.

Adolescents and children worldwide are threatened by osteosarcoma, a tumor that predominantly affects the long bone epiphysis. Osteosarcoma is the most common and highly malignant bone tumor in youngsters. Early tumor detection is the key to effective treatment of this disease. The discovery of biomarkers and the growing understanding of molecules and their complex interactions have improved the outcome of clinical trials in osteosarcoma. This article describes biomarkers of osteosarcoma with the aim of positively influencing the progress of clinical treatment of osteosarcoma. Femoral bone tumor is a typical condition of osteosarcoma. Due to the wide range of femoral stem types, complexities in the distal femur, and tumors in the rotor part of femur, physicians following the traditional clinical approach face difficulties in removing the lesion and fixing the femur with resection of the tumor segment. In this paper, the effect of small doses of different concentrations of lidocaine anesthesia in patients undergoing lumpectomy for osteosarcoma femoral tumor segments is investigated. A computer-based artificial intelligence method for automated determination of different concentration levels of lidocaine anesthesia and amputation of osteosarcoma femoral tumor segment is proposed. Statistical analysis is carried on the empirical data including intraoperative bleeding, intraoperative and postoperative pain scores, surgical operation time, postoperative complications, patient satisfaction, and local anesthetic dose. The results showed that the patients in the study group had low intraoperative bleeding, short operation time, low postoperative hematoma formation rate, high patient satisfaction, higher dosage of anesthetic solution, and low dosage of lidocaine. Results revealed that mean arterial pressure and heart rate in extubating and intubating were significantly lower in the observation group than in the control group, and a significant difference (P < 0.05) was observed between the two groups. This proves that the proposed algorithm can adequately reduce bleeding, alleviate postoperative pain, shorten operation time, reduce complications, accelerate recovery, and ensure better treatment results.

Does a single dose of palonosetron have any role in preventing acute chemotherapy-induced nausea and vomiting in pediatric osteosarcoma patients without dexamethasone? A randomized clinical trial.

BACKGROUND: Chemotherapy-induced nausea and vomiting (CINV) is a troublesome side-effect of chemotherapy in pediatric patients undergoing osteosarcoma treatment. In this context, the role of 5-hydroxytryptamine-3 (5-HT3) receptor antagonists needs to be explored. OBJECTIVES: To evaluate the superiority of single-dose palonosetron over granisetron in pediatric patients undergoing highly emetogenic chemotherapy (HEC) for osteosarcoma. MATERIAL AND METHODS: In this double-blind, randomized study, pediatric patients were assessed in terms of acute nausea and vomiting following HEC for osteosarcoma. These children were assigned to group 1 (palonosetron) and group 2 (granisetron) without any other antiemetic prophylaxis. The primary outcome variable was the children's segment with a complete response (CR) during the acute phase of the 1st on-study chemotherapy cycle. The risk factors associated with the emesis were analyzed. The patients were followed up for the first 24 h after chemotherapy. RESULTS: A total number of 200 children were evaluated in terms of the response, and other factors that might alter the response were assessed in the 2 groups. These 200 children underwent 604 blocks of chemotherapy. Complete responses were documented in 83% and 72% of children receiving palonosetron and granisetron, respectively, during the acute phase. Only dexamethasone, used as a rescue medication, was found to be a significant risk factor that predisposed to the response (p < 0.05). CONCLUSIONS: Single-dose palonosetron is an effective alternative to granisetron for preventing CINV in children receiving HEC for osteosarcoma.

A case-control study of topical and supplemental fluoride use and osteosarcoma risk.

BACKGROUND: A relationship between fluoride and osteosarcoma has been hypothesized but not validated. To the authors' knowledge, there are no published studies examining topical fluoride or dietary fluoride supplements and osteosarcoma risk. The purpose of this study was to examine the association between ever or never use of topical and dietary fluoride supplements and osteosarcoma. METHODS: The authors performed a secondary data analysis on data from 2 separate but linked studies. Patients for Phase 1 and Phase 2 were selected from US hospitals using a hospital-based matched case-control study design. Case patients were those who had received diagnoses of osteosarcoma, and control patients were those who had received diagnoses of other bone tumors or nonneoplastic conditions. In Phase 1, case patients (N = 209) and control patients (N = 440) were those seeking treatment at orthopedic departments from 1989 through 1993. In Phase 2, incident case patients (N = 108) and control patients (N = 296) were identified and treated by physicians from 1994 through 2000. This analysis included all patients who met eligibility criteria and on whom the authors had complete data on exposure, outcome, and covariates. The authors used conditional logistic regression to estimate odds ratios and 95% confidence intervals (CIs) for the association of topical fluoride use and supplemental fluoride use with osteosarcoma. RESULTS: The adjusted odds ratios were 0.94 (95% CI, 0.60 to 1.46) and 0.78 (95% CI, 0.46 to 1.33) for topical fluoride and supplemental fluoride, respectively. CONCLUSIONS: Neither topical nor dietary fluoride supplements are associated with an increased risk of developing osteosarcoma. PRACTICAL IMPLICATIONS: Supplemental and topical fluorides used in the dental office and in over-the-counter products are not related to an increased risk of developing osteosarcoma.

Teriparatide Did Not Increase Adult Osteosarcoma Incidence in a 15-Year US Postmarketing Surveillance Study.

The Osteosarcoma Surveillance Study was initiated in the United States in 2003 to monitor for a potential association between the osteoporosis treatment teriparatide and osteosarcoma. Osteosarcoma occurs at a background incidence rate of approximately 2.5 cases per million per year in US adults aged 40 years or older. For this study, incident cases of osteosarcoma diagnosed between January 1, 2003, and December 31, 2016, were identified through participating cancer registries in the United States. Information on prior exposure to medications and possible risk factors was obtained by self-report (or proxy report) in telephone interviews. Exposure information was verified through medical record abstraction for a sample of patients. A standardized incidence ratio was estimated to compare the observed and expected numbers of osteosarcoma patients with a prior history of teriparatide treatment. Interviews were completed for 24% (1173) of patients diagnosed with osteosarcoma between 2003 and 2016; three reports of teriparatide use before diagnosis were identified. Based on the background incidence rate, the expected number of osteosarcoma cases among patients treated with teriparatide was 4.17. Given the three observed cases, the standardized incidence ratio was 0.72 (90% confidence interval [CI], 0.20 to 1.86). Demographic characteristics were similar for interviewed and noninterviewed patients. Agreement was >90% between self-reported and chart-recorded exposure to osteoporosis medications. Mean age of interviewed patients was 61 years; 53% of patients were male, 84% were white, and 5% were Hispanic. The prevalence of suspected risk factors for development of osteosarcoma among the osteosarcoma cohort was 19% for history of radiation and 4% for history of Paget's disease of bone. These findings showed that the incidence of osteosarcoma associated with teriparatide use during the 15-year surveillance period was no different than would be expected based on the background incidence rate of osteosarcoma. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Assessing the incidence of osteosarcoma among teriparatide users based on Medicare Part D and US State Cancer Registry Data.

PURPOSE: During preclinical testing, teriparatide caused a dose-dependent increase in the incidence of osteosarcoma in rats. This study compared the incidence rate of osteosarcoma among patients aged ≥65 years treated with teriparatide vs a matched-comparator cohort. METHODS: This population-based comparative-cohort study matched exposure details for each teriparatide user, identified via Medicare Part D prescription claims, and up to four comparators based on age, sex, zip code, date of claim for filled prescription, and number of unique therapeutic classes dispensed. Outcomes were identified via linkage with participating cancer registries. All US state cancer registries were invited to participate. RESULTS: Overall, 153 316 patients in the teriparatide cohort and 613 247 in the comparator cohort were linked to 811 osteosarcoma cases from 26 participating state cancer registries (68% of US patients aged ≥65 years diagnosed 2007-2014). Analysis on a subset of cohorts revealed they were balanced for known osteosarcoma risk factors and Charlson comorbidity index. Mean duration of teriparatide treatment was 10 months. No osteosarcoma cases were observed in the teriparatide cohort; the incidence rate in the comparator cohort was consistent with the background incidence rate among adults aged ≥65 years. The incidence rate ratio was 0.0 (95% confidence interval, 0.0-3.2). CONCLUSIONS: For US patients aged ≥65 years, incidence of osteosarcoma among those treated with teriparatide ranges from 0 to 3.2 times the incidence of osteosarcoma in those treated with other medications. Given low incidence of osteosarcoma, this range of effect is inconsistent with a large absolute increase in osteosarcoma risk.

Skeletal impact of 17ß-estradiol in T cell-deficient mice: age-dependent bone effects and osteosarcoma formation.

Estrogen (E2)-dependent ER+ breast cancer, the most common breast cancer subtype, is also the most likely to metastasize to bone and form osteolytic lesions. However, ER+ breast cancer bone metastasis human xenograft models in nude mice are rarely studied due to complexities associated with distinguishing possible tumoral vs. bone microenvironmental effects of E2. To address this knowledge gap, we systematically examined bone effects of E2 in developing young (4-week-old) vs. skeletally mature (15-week-old) female Foxn1nu nude mice supplemented with commercial 60-day slow-release E2 pellets and doses commonly used for ER+ xenograft models. E2 pellets (0.05-0.72 mg) were implanted subcutaneously and longitudinal changes in hind limb bones (vs. age-matched controls) were determined over 6 weeks by dual-energy X-ray absorptiometry (DXA), microCT, radiographic imaging, and histology, concurrent with assessment of serum levels of E2 and bone turnover markers. All E2 doses tested induced significant and identical increases in bone density (BMD) and volume (BV/TV) in 4-week-old mice with high bone turnover, increasing bone mineral content (BMC) while suppressing increases in bone area (BA). E2 supplementation, which caused dose-dependent changes in circulating E2 that were not sustained, also led to more modest increases in BMD and BV/TV in skeletally mature 15-week-old mice. Notably, E2-supplementation induced osteolytic osteosarcomas in a subset of mice independent of age. These results demonstrate that bone effects of E2 supplementation should be accounted for when assessing ER+ human xenograft bone metastases models.

Integrative analyses of key genes and regulatory elements in fluoride-affected osteosarcoma.

Osteosarcoma is one of the most malignant tumors in adolescents with severe outcomes while fluoride is one of the most abundant elements in the environment. Epidemiological evidence has elucidated the relationship between fluoride and osteosarcoma, but the molecular mechanisms are extremely complicated. Microarray profiles were downloaded from the Gene Expression Omnibus database to identify differentially expressed genes (DEGs) in the progression of fluoride-affected osteosarcoma. The functional enrichment analysis was performed, a protein-protein interaction network, a microRNA-messenger RNA (mRNA) and a transcription factors-mRNA regulatory network were constructed and performed using Search Tool for the Retrieval of Interacting Genes (STRING) and Cytoscape. A total of 171 DEGs were identified. The functions and pathways of the DEGs were enriched in nucleolus, protein ubiquitination, protein binding, RNA transport, and the spliceosome. Eighteen hub genes were identified and functional analysis revealed that these genes are mainly enriched in protein binding, nucleoplasm, and ribosomal RNA processing. Survival analysis showed that the hub genes may be involved in the invasion or recurrence of osteosarcoma. In conclusion, the DEGs and hub genes with their regulatory elements identified in this study will help us understand the molecular mechanisms underlying fluoride-affected osteosarcoma and provide candidate targets for future research.

Attenuation of STAT3 Phosphorylation Promotes Apoptosis and Chemosensitivity in Human Osteosarcoma Induced by Raddeanin A.

Osteosarcoma (OS) is the most common primary bone malignancy in adolescents. One major obstacle for current OS treatment is drug-resistance. Raddeanin A (RA), an oleanane-type triterpenoid saponin, exerts anti-tumor effects in several tumor models, but the effect of RA in human drug-resistant OS remained to be elucidated. In the present study, we investigated the anti-tumor effects of RA in both drug-sensitive and drug-resistant OS cells and its underlying mechanism. RA inhibited cell proliferation and colony formation and induced apoptotic cell death in a dose-dependent manner in both drug-sensitive and drug-resistant cells. Moreover, RA exposure resulted in the inhibition of interleukin-6 (IL-6)-induced JAK2/STAT3 signaling pathway activation and target gene expression in both drug-sensitive and drug-resistant cells. Meanwhile, we observed significantly increased MDR1 and STAT3 expression in drug-resistant OS cells compared with parental cells. STAT3 overexpression promoted chemo-resistance and MDR1 protein expression in both drug-sensitive OS cells and drug-resistant OS cells, while inhibiting STAT3 with siRNA sensitized OS cells to doxorubicin treatment. In addition, RA synergistically increased doxorubicin toxicity by increasing its cellular uptake, ablating efflux and downregulating MDR1 in drug-resistant cells with attenuation of STAT3 Phosphorylation. Finally, RA suppressed in vivo tumor growth and induced apoptosis in nude mouse using drug-resistant OS tibia orthotopic model. Taken together, RA is a promising potential therapeutic for the treatment of doxorubicin resistance in OS.

The Forteo Patient Registry linkage to multiple state cancer registries: study design and results from the first 8 years.

The Forteo Patient Registry (FPR) aims to estimate the incidence of osteosarcoma in US patients treated with teriparatide. Enrollment began in 2009 and will continue through 2019, with linkage planned through 2024. To date, no incident cases of osteosarcoma have been identified among patients registered in the FPR. INTRODUCTION: The Forteo Patient Registry (FPR) was established in 2009 to estimate the incidence of osteosarcoma in US patients treated with teriparatide. The objective of this paper is to describe study methods, challenges encountered, and progress to date. METHODS: The FPR is a prospective US registry designed to link data from participants annually with state cancer registries. Patient enrollment is planned for 10 years (2009-2019) and annual linkage with US state cancer registries for 15 years (2010-2024). All US state cancer registries and DC were invited to participate. Patients are recruited using pre-enrollment materials included in teriparatide device packaging, kits, and brochures distributed by health-care providers; a toll-free number; and a study website. A linkage algorithm is used to match data from enrolled participants with cancer registry data. RESULTS: For the eighth annual linkage in 2017, information necessary for linkage with 63,270 patients in the FPR was submitted to each of the 42 participating registries. These patients contributed approximately 242,782 person-years of follow-up. A total of 5268 adult osteosarcoma cases diagnosed since January 1, 2009, were available for linkage from participating state cancer registries. To date, no incident cases of osteosarcoma have been identified among patients registered in the FPR. CONCLUSIONS: Based on the estimated 242,782 person-years of observation as of the eighth annual linkage and projecting current enrollment rate to study end in 2024, it is anticipated that the completed study will be able to detect a fourfold increase in the risk of osteosarcoma if one exists.

Connective tissue growth factor stimulates osteosarcoma cell migration and induces osteosarcoma metastasis by upregulating VCAM-1 expression.

Osteosarcoma is the most common bone malignancy that occurs in the young population. After osteosarcoma cells metastasize to the lung, prognosis is very poor owing to difficulties in early diagnosis and effective treatment. Recently, connective tissue growth factor (CTGF) was reported to be a critical contributor to osteosarcoma metastasis. However, the detailed mechanism associated with CTGF-directed migration in bone neoplasms is still mostly unknown. Through the in vivo and in vitro examination of osteosarcoma cells, this study suggests that VCAM-1 up-regulation and increased osteosarcoma cell migration are involved in this process. Antagonizing αvß3 integrin inhibited cell migration. Moreover, FAK, PI3K, Akt and NF-κB activation were also shown to be involved in CTGF-mediated osteosarcoma metastasis. Taken together, CTGF promotes VCAM-1 production and further induces osteosarcoma metastasis via the αvß3 integrin/FAK/PI3K/Akt/NF-κB signaling pathway, which could represent a promising clinical target to improve patient outcome.

Fluoride Exposure in Early Life as the Possible Root Cause of Disease In Later Life.

Fluoride, one of the most celebrated ingredients for the prevention of dental caries in the 20th century, has also been controversial for its use in dentifrices and other applications. In the current review, we have concentrated primarily on early-life exposure to fluoride and how it may affect the various organs. The most recent controversial aspects of fluoride are related to toxicity of the developing brain and how it may possibly result in the decrease of intelligence quotient (IQ), autism, and calcification of the pineal gland. In addition, it has been reported to have possible effects on bone and thyroid glands. If nutritional stress is applied during a critical period of growth and development, the organ(s) and/or body will never recover once they pass through the critical period. For example, if animals are force-fed during experiments, they will simply get fat but never reach the normal size. Although early-life fluoride exposure causing fluorosis is well reported in the literature, the dental profession considers it primarily as an esthetic rather than a serious systemic problem. In the current review, we wanted to raise the possibility of future disease as a result of early-life exposure to fluoride. It is not currently known how fluoride will become a cause of future disease. Studies of other nutritional factors have shown that the effects of early nutritional stress are a cause of disease in later life.

Ezrin/NF-κB Pathway Regulates EGF-induced Epithelial-Mesenchymal Transition (EMT), Metastasis, and Progression of Osteosarcoma.

BACKGROUND Epithelial-mesenchymal transition (EMT) is responsible for metastasis of cancers, and NF-κB can promote tumor progression. Ezrin is an important molecule participating in EMT. However, whether Ezrin mediates NF-κB in EGF-induced osteosarcoma is unknown. MATERIAL AND METHODS Ezrin phosphorylation, NF-κB activation, and EGF-induced EMT were studied in MG63 and U20S cells with NF-κB inhibition, silencing, or over-expressing Ezrin. Cell morphology, proliferation, migration, and motility were analyzed. An osteosarcoma model was established in mice by injecting MG63 and U20S and reducing Ezrin. RESULTS With EGF induction in vitro, Ezrin Tyr353 and Thr567 were phosphorylated, and EMT, proliferation, migration, and motility of osteosarcoma cells were promoted. Silencing Ezrin suppressed and over-expressing Ezrin promoted the nuclear translocation of p65 and phosphorylated IκBα (p-IκBα) in EGF-induced osteosarcoma cells. NF-κB inhibitor blocked EGF-induced EMT in both cell types, as well as reserving cell morphology and suppressing proliferation, migration, and motility. In vivo, reducing Ezrin significantly suppressed metastasis of osteosarcoma xenografts, increased liver and lung weights, and activated NF-κB, which were both induced by EGF. CONCLUSIONS Ezrin/NF-κB regulated EGF-induced EMT, as well as progression and metastasis of osteosarcoma in vivo and in vitro. Ezrin/NF-κB may be a new therapeutic target to prevent osteosarcoma from deterioration.

Oleanolic acid induces osteosarcoma cell apoptosis by inhibition of Notch signaling.

Oleanolic acid (OA), a naturally occurring triterpenoid, exhibits potential antitumor activity in several tumor cell lines. Although the inhibition effects of OA on proliferation and survival in human cancers have been confirmed, the potential mechanism underlying OA-induced osteosarcoma cell death has not yet been fully elucidated. Our results in this study showed that OA inhibits proliferation and viability of osteosarcoma cells in a dose-dependent manner. Flow cytometry assays revealed that apoptosis in osteosarcoma cells was significantly induced by OA treatment, while this induction was blocked by Jagged1-mediated activation of Notch signaling. Western blot analysis and a mitochondrial membrane potential assay demonstrated that OA functions through the mitochondrial apoptosis pathway. More importantly, our data revealed that OA treatment interrupted the balance between pro-apoptotic factors and anti-apoptotic factors in osteosarcoma cells by inhibition of the Notch signaling pathway. These data suggest that OA induces osteosarcoma cell apoptosis by targeting mitochondria in a Notch signaling-dependent manner. Thus, OA may be a promising drug for adjuvant chemotherapy in osteosarcoma.

Development of high-grade osteosarcoma in a patient with recurrent giant cell tumor of the ischium while receiving treatment with denosumab.

Malignant transformation of giant cell tumor of bone (GCTB) without radiotherapy exposure is exceptionally rare, occurring in less than 1% of GCTBs. The safety and efficacy of denosumab in patients with GCTB was recently reported. We herein report a case of a benign recurrent GCTB with an H3F3A mutation that underwent secondary malignant transformation during treatment with denosumab. A 29-year-old woman underwent curettage of a GCTB of the left ischium in 2005. Ten years after the first surgery, the GCTB recurred locally. We started treatment with denosumab. During the first 5 months of treatment, we observed a demarcated area of osteosclerosis in the recurrent lesion, and the patient's clinical condition improved. At 6 months, however, the patient developed pain, and a rapidly growing mass was detected by computed tomography. An incisional biopsy was performed. Histologic analysis showed a high-grade osteosarcoma. The patient developed lung metastases and died soon after beginning chemotherapy. The mechanism of sarcomatous transformation of GCTB during denosumab therapy is unclear. These findings suggest that the scientific community should be aware of the possible malignant transformation of GCTB during denosumab treatment.

Comparing the incidence of bone tumors in rats chronically exposed to the selective PTH type 1 receptor agonist abaloparatide or PTH(1-34).

Prolonged treatment with human parathyroid hormone (hPTH) in rats results in development of bone tumors, though this finding has not been supported by clinical experience. The PTH type 1 receptor agonist abaloparatide, selected for its bone anabolic activity, is under clinical development to treat postmenopausal women with osteoporosis. To determine the carcinogenic potential of abaloparatide, Fischer (F344) rats were administered SC daily abaloparatide at doses of 0, 10, 25, and 50 µg/kg or 30 µg/kg hPTH(1-34) as a positive control for up to 2 years. Robust increases in bone density were achieved at all abaloparatide doses and with hPTH(1-34). Comprehensive histopathological analysis reflected a comparable continuum of proliferative changes in bone, mostly osteosarcoma, in both abaloparatide and hPTH(1-34) treated rats. Comparing the effects of abaloparatide and hPTH(1-34) at the 25 and 30 µg/kg respective doses, representing similar exposure multiples to the human therapeutic doses, revealed similar osteosarcoma-associated mortality, tumor incidence, age at first occurrence, and metastatic potential. There were no increases in the incidence of non-bone tumors with abaloparatide compared to vehicle. Thus, near life-long treatment with abaloparatide in rats resulted in dose and time dependent formation of osteosarcomas, with a comparable response to hPTH(1-34) at similar exposure.

Evaluation of optimal water fluoridation on the incidence and skeletal distribution of naturally arising osteosarcoma in pet dogs.

Experimental toxicological studies in laboratory animals and epidemiological human studies have reported a possible association between water fluoridation and osteosarcoma (OSA). To further explore this possibility, a case-control study of individual dogs evaluated by the UC Davis Veterinary Medical Teaching Hospital was conducted using ecologic data on water fluoridation based on the owner's residence. The case group included 161 dogs with OSA diagnosed between 2008-2012. Two cancer control groups included dogs diagnosed with lymphoma (LSA) or hemangiosarcoma (HSA) during the same period (n = 134 and n = 145, respectively). Dogs with OSA were not significantly more likely to live in an area with optimized fluoride in the water than dogs with LSA or HSA. Additional analyses within OSA patients also revealed no significant differences in age, or skeletal distribution of OSA cases relative to fluoride status. Taken together, these analyses do not support the hypothesis that optimal fluoridation of drinking water contributes to naturally occurring OSA in dogs.