The role of bisphosphonates in the management of patients that have cancer

An evaluation of the combination effect of zoledronate and chemotherapeutic agents in canine osteosarcoma cells

Introduction

Osteosarcoma (OSA) is an aggressive form of bone cancer in both dogs and humans. The treatment options for metastatic (stage III) OSA are currently limited and the prognosis is poor. Zoledronate, a second generation amino-bisphosphonate, is commonly used for palliation of cancer induced bone pain. Zoledronate has also demonstrated anti-cancer properties and possibly enhances the cytotoxicity of doxorubicin in a canine histiocytosis cell line and human prostatic cancer cell line. The goal of this study was to evaluate the combination effect of zoledronate and various chemotherapeutic drugs in canine OSA cells.

Methods

Canine OSA cell line (D17), cells from two canine primary OSAs, and MDCK, a canine kidney cell line, were used to evaluate the therapeutic potential of these drugs. Carboplatin, doxorubicin, vinorelbine, toceranib, and isophosphoramide mustard (active metabolite of ifosfamide) were used as chemotherapeutic agents. First, cells were treated with either zoledronate or chemotherapy drug alone for 72 hours. Cell viability was assessed using CellTiter Glo and IC5, IC10, IC20, and IC50 were calculated. Second, cells were treated with a combination of zoledronate and each chemotherapeutic agent at their IC5, IC10, IC20, and IC50 concentrations. After 72 hours, cell viability was assessed by CellTiter Glo.

Results and discussion

Zoledronate, carboplatin, doxorubicin, vinorelbine, and isophosphoramide mustard showed concentration dependent decrease in cell viability. Toceranib showed decreased cell viability only at higher concentrations. When zoledronate was used in combination with chemotherapy drugs, while it showed potential synergistic effects with toceranib, potential antagonistic effects with vinorelbine and isophosphoramide mustard were observed. However, the results differed by cell line and thus, further evaluation is warranted to understand the exact mechanism of action.

Effects of neoadjuvant zoledronate and radiation therapy on cell survival, cell cycle distribution, and clinical status in canine osteosarcoma

Introduction

Zoledronic acid (ZOL) is a third-generation bisphosphonate with a higher affinity for bone resorption areas than earlier bisphosphonates (i.e., pamidronate, PAM). In human medicine, ZOL provides improved bone pain relief and prolonged time to skeletal-related events compared to its older generational counterparts. Preclinical studies have investigated its role as an anti-neoplastic agent, both independently and synergistically, with radiation therapy (RT). ZOL and RT act synergistically in several neoplastic human cell lines: prostate, breast, osteosarcoma, and fibrosarcoma. However, the exact mechanism of ZOL's radiosensitization has not been fully elucidated.

Methods

We investigated ZOL's ability to induce apoptosis in canine osteosarcoma cell lines treated with various doses of megavoltage external beam radiotherapy. Second, we evaluated cell cycle arrest in ZOL-treated cells to assess several neo-adjuvant time points. Finally, we treated 20 dogs with naturally occurring appendicular OS with 0.1 mg/kg ZOL IV 24 h before receiving 8 Gy of RT (once weekly fraction x 4 weeks).

Results

We found that apoptosis was increased in all ZOL-treated cell lines compared to controls, and the combination of ZOL and RT resulted in dissimilar apoptosis between Abrams and D-17 and HMPOS cell lines. Cell cycle arrest (G2/M phase) was minimal and variable between cell lines but perhaps greatest at 48 h post-ZOL treatment. Only 10% of dogs treated with ZOL and RT developed pathologic fractures, compared to 44% of dogs historically treated with PAM and RT (p = 0.027).

Discussion

ZOL and RT appear to be a well-tolerated combination treatment scheme for non-surgical candidates; future studies must elucidate the ideal timing of ZOL.

Fracture rate and time to fracture in dogs with appendicular osteosarcoma receiving finely fractionated compared to coarsely fractionated radiation therapy: A single institution study

BACKGROUND

Radiation therapy (RT) is used for local pain alleviation in dogs with appendicular osteosarcoma (OS), especially among dogs that are poor surgical candidates for amputation. However, many historical reports of fractionated protocols lack time to fracture and fracture rates.

OBJECTIVES

The primary objectives of this retrospective study were to determine fracture rate and time to fracture of dogs receiving RT (coarse or fine fractionated) for appendicular OS. Secondary objectives were to evaluate tolerability and disease outcome measures.

METHODS

Fifty-one dogs that received RT as part of treatment for appendicular OS were available for evaluation. Forty-five received coarse fractionation (C-RT, 8 or 6 Gy per fraction protocols [C-RT8 or C-RT6]) while the remaining six received fine fractionation (F-RT).

RESULTS

The overall pathologic fracture rate was 37%. Pathologic fracture rate was significantly higher for dogs that received F-RT (5/6, 83%) compared to dogs that received C-RT (12/40, 30%, p = 0.021). In the 17 dogs that fractured, the overall median time to fracture was 57 days. For all dogs, the median progression free interval (PFI) and median overall survival time (OST) were 90 and 140 days, respectively. In a very small cohort of dogs (n = 7) treated with zoledronate and RT, fracture rate was 0% and extended survival times were noted.

CONCLUSIONS

In conclusion, C-RT is recommended over F-RT due to lower risk of pathologic fracture and similar PFI. Prospective evaluation of combined C-RT and zoledronate, especially for dogs with poor surgical candidacy, is warranted for the treatment of canine appendicular osteosarcoma.

Retrospective Evaluation of Acute Kidney Injury After Zoledronic Acid Administration to Dogs With Malignant Osteolysis

Zoledronic acid (ZOL) is an intravenous bisphosphonate indicated for the use of hypercalcemia of malignancy and management of bony metastases. Its therapeutic effect lies in the targeting of malignant osteoclasts; however, administration can be associated with renal toxicity. The objective of this retrospective study was to evaluate the frequency and severity of acute kidney injury (AKI) following ZOL administration in a cohort of cancer-bearing dogs. A pharmacy search was conducted to identify dogs that received a dose of ZOL between June 2016 and July 2019. Inclusion criteria included baseline and post-treatment chemistry panels. Medical records were reviewed to obtain clinical data including signalment, dose, dosage, number of treatments administered, and changes in renal function. Forty-four dogs met the inclusion criteria. Median number of doses administered was three [interquartile range (IQR), 2–5]. The median highest creatinine value occurred after a median of one dose (IQR, 1–2 doses) compared with the median highest value of blood urea nitrogen, phosphorus, and potassium, which occurred after a median of two doses (IQR, 1–3). Six (13.6%) dogs developed an AKI, and one dog (2.3%) had progression of an existing azotemia after treatment with ZOL was initiated. Two dogs (4.5%) had ZOL treatment discontinued secondary to development of azotemia. Use of concurrent administration of non-steroidal anti-inflammatory drugs or anesthesia did not significantly increase the risk of AKI in this cohort of dogs. Acute kidney injury is observed infrequently in cancer-bearing dogs treated with ZOL and is generally mild to moderate in severity; discontinuation of ZOL due to AKI is uncommon.

Medication-related osteonecrosis of the jaw after long-term bisphosphonate treatment in a cat

A 12‐year‐old, neutered female, domestic medium hair cat was evaluated for a nonhealing, oral mucosal ulceration. The cat had a history of idiopathic hypercalcemia that had been treated with a bisphosphonate for 41 months. Oral examination identified exposed maxillary bone adjacent to a previous extraction site. Histopathology of the exposed bone and associated mucosa was most consistent with medication‐related osteonecrosis of the jaw. Treatment involved both medical and surgical interventions. Oral mucosal healing occurred after 6 months of treatment.

SAFETY AND TOXICITY OF AN ACCELERATED COARSELY FRACTIONATED RADIATION PROTOCOL FOR TREATMENT OF APPENDICULAR OSTEOSARCOMA IN 14 DOGS: 10 GY × 2 FRACTIONS

Coarsely fractionated radiation is commonly used as a method for pain control in dogs with appendicular osteosarcoma, however there is little published information on optimal protocols. The aim of this retrospective, descriptive study was to report safety and toxicity findings in a sample of dogs with appendicular osteosarcoma that had been treated with a radiation scheme of 10 Gy delivered over two consecutive days for a total of 20 Gy. Dogs were included in the study if they had osteosarcoma that was treated with the aforementioned protocol. Dogs were excluded if treated with the same protocol for any other bone tumor besides osteosarcoma or inadequate follow-up. Thirteen of the 14 patients received adjuvant therapy with pamidronate and a nonsteroidal anti-inflammatory. Nine dogs received adjuvant chemotherapy with carboplatin after radiation was complete. Within a median of 14 days, 92.8% of dogs subjectively had improved pain control. Median duration of response (DOR) was 80 days (range 20-365). The majority of patients developed VRTOG grade one toxicity, primarily alopecia. Five dogs (35.7%) developed pathologic fracture postradiation treatment. Timing of fracture was variable ranging from 24 to 250 days. This radiation protocol was well tolerated, with minimal toxicity, subjectively improved survival time, and had the benefit of being completed in two consecutive days.

Zoledronic acid induces apoptosis via stimulating the expressions of ERN1, TLR2, and IRF5 genes in glioma cells

Glioblastoma multiforme (GBM) is the most common and aggressive brain tumor that affects older people. Although the current therapeutic approaches for GBM include surgical resection, radiotherapy, and chemotherapeutic agent temozolomide, the median survival of patients is 14.6 months because of its aggressiveness. Zoledronic acid (ZA) is a nitrogen-containing bisphosphonate that exhibited anticancer activity in different cancers. The purpose of this study was to assess the potential effect of ZA in distinct signal transduction pathways in U87-MG cells. In this study, experiments performed on U87-MG cell line (Human glioblastoma-astrocytoma, epithelial-like cell line) which is an in vitro model of human glioblastoma cells to examine the cytotoxic and apoptotic effects of ZA. IC50 dose of ZA, 25 μM, applied on U87-MG cells during 72 h. ApoDIRECT In Situ DNA Fragmentation Assay was used to investigate apoptosis of U87MG cells. The quantitative reverse transcription polymerase chain reaction (qRT-PCR) (LightCycler480 System) was carried out for 48 gene expression like NF-κB, Toll-like receptors, cytokines, and inteferons. Our results indicated that ZA (IC50 dose) increased apoptosis 1.27-fold in U87MG cells according to control cells. According to qRT-PCR data, expression levels of the endoplasmic reticulum-nuclei-1 (ERN1), Toll-like receptor 2 (TLR2), and human IFN regulatory factor 5 (IRF5) tumor suppressor genes elevated 2.05-, 2.08-, and 2.3-fold by ZA, respectively, in U87MG cells. Our recent results indicated that ZA have a key role in GBM progression and might be considered as a potential agent in glioma treatment.

Treatment of ionized hypercalcemia in 12 cats (2006-2008) using PO-administered alendronate

Background

Long‐term treatment of cats with ionized hypercalcemia using alendronate has not been evaluated.

Hypothesis/Objectives

Alendronate is well tolerated in treatment of ionized hypercalcemia in cats.

Animals

A total of 12 cats with ionized hypercalcemia.

Methods

Prospective study of 12 cats with ionized hypercalcemia of idiopathic origin was identified by telephone and email communication with a convenience sample of consulting veterinarians. Cats were treated with alendronate at a dose of 5–20 mg per feline PO q7d. Serum ionized calcium concentration (iCa) was measured before beginning treatment with alendronate, and after 1, 3, and 6 months of treatment. Alendronate dosage was adjusted according to iCa. Evaluation included physical examination, CBC, biochemistry profile, and diagnostic imaging. The owners and referring veterinarians were questioned about any observed adverse effects. The Wilcoxon matched‐pairs signed rank test was used to compare baseline iCa to iCa at different time periods.

Results

Alendronate treatment resulted in a decrease in iCa in all 12 cats. The median percentage change in iCa was −13.2%, −15.9%, and −18.1% (range, −29.6 to +7.6; −30.5 to −1.9; −45.8 to +1.5%) at the 1, 3, and 6 month time points, respectively. Baseline iCa was significantly different from 1 month (P = .0042), 3 months (P = .0005), and 6 months (P = .0015). No adverse effects were reported for any of the cats.

Conclusions and Clinical Importance

Alendronate was well tolerated and decreased iCa in most cats for the 6‐month period of observation.

The impact of pamidronate and chemotherapy on survival times in dogs with appendicular primary bone tumors treated with palliative radiation therapy

OBJECTIVE

To assess survival times in dogs that received palliative radiation therapy (RT) alone, and in combination with chemotherapy, pamidronate, or both for primary appendicular bone tumors and determine whether the addition of these adjunctive therapies affects survival.

STUDY DESIGN

Retrospective case series.

ANIMALS

Dogs (n = 50) with primary appendicular bone tumors.

METHODS

Dogs were divided into the following treatment groups: RT alone, RT + chemotherapy, RT+ pamidronate, and RT+ chemotherapy + pamidronate. Dogs were considered for analysis if they had a known euthanasia date or follow-up data were available for at least 120 days from the time of diagnosis. Survival time was defined as the time from admission to euthanasia. Cox proportional hazard models and Kaplan-Meier survival functions were used. A P value of less than .05 was considered significant.

RESULTS

Fifty dogs were considered for survival analysis. Median survival times (MSTs) were longest for dogs receiving RT and chemotherapy (307 days; 95% CI: 279, 831) and shortest in dogs receiving RT and pamidronate (69 days; 95% CI: 47, 112 days). The difference in MST between dogs who received pamidronate and those who did not in this population was statistically significant in a univariate (P = .039) and multivariate analysis (P = .0015). The addition of chemotherapy into any protocol improved survival (P < .001).

CONCLUSIONS

Chemotherapy should be recommended in addition to a palliative RT protocol to improve survival of dogs with primary appendicular bone tumors. When combined with RT ± chemotherapy, pamidronate decreased MST and should not be included in a standard protocol.

Acute management of calcium disorders

Acute management of hypercalcemia and hypocalcemia is an important part of small-animal emergency practice. In addition to hypercalcemia of malignancy and hyperparathyroidism, vitamin D toxicosis is becoming more common in companion animals as new and improved rodenticides and human pharmaceutical preparations (vitamin D analog skin creams) become more available. This article provides complete details regarding the emergency management of life-threatening hypercalcemia with focus on vitamin D intoxication. At the other end of the spectrum, hypocalcemic emergencies, such as periparturient hypocalcemia (eclampsia), may be less common but are often life threatening. This article contains guidelines for the emergency management of hypocalcemia. In summary, the urgent care of calcium disorders in small animals is reviewed.

Bisphosphonate related osteonecrosis of the jaws: a review

Bisphosphonate use has increased in veterinary medicine over the last decade. During this time, bisphosphonate related osteonecrosis of the jaws (BRONJ) in human patients has been identified. Only recently was a dog model for BRONJ developed for human oral surgery and medicine. Veterinary patients treated with bisphosphonates may be at an increased risk for BRONJ There has been little, to no, investigation of potential long term side-effects of bisphosphonate use in veterinary patients; potential sequelae are unknown. The history of bisphosphonates, their use, and BRONJ in veterinary patients are discussed.

Models for anti-tumor activity of bisphosphonates using refined topochemical descriptors

An in silico approach comprising of decision tree (DT), random forest (RF) and moving average analysis (MAA) was successfully employed for development of models for prediction of anti-tumor activity of bisphosphonates. A dataset consisting of 65 analogues of both nitrogen-containing and non-nitrogen-containing bisphosphonates was selected for the present study. Four refinements of eccentric distance sum topochemical index termed as augmented eccentric distance sum topochemical indices 1-4 [formula: see text] have been proposed so as to significantly augment discriminating power. Proposed topological indices (TIs) along with the exiting TIs (>1,400) were subsequently utilized for development of models for prediction of anti-tumor activity of bisphosphonates. A total of 43 descriptors of diverse nature, from a large pool of molecular descriptors, calculated through E-Dragon software (version 1.0) and an in-house computer program were selected for development of suitable models by employing DT, RF and MAA. DT identified two TIs as most important and classified the analogues of the dataset with an accuracy of 97% in training set and 90.7% in tenfold cross-validated set. Random forest correctly classified the analogues with an accuracy of 89.2%. Four independent models developed through MAA predicted the activity of analogues of the dataset with an accuracy of 87.6% to 89%. The statistical significance of proposed models was assessed through intercorrelation analysis, specificity, sensitivity and Matthew's correlation coefficient. The proposed models offer a vast potential for providing lead structures for development of potent anti-tumor agents for treatment of cancer that has spread to the bone.