Disease modifying and anti-nociceptive effects of the bisphosphonate, zoledronic acid in a model of bone cancer pain

Targeting Ras and Rho GTPases as opportunities for cancer therapeutics

The Ras and Rho GTPases contribute to the initiation and progression of cancer by subverting the normal regulation of specific intracellular signalling pathways. As a result, Ras and Rho play significant roles in the development of numerous aspects of the malignant phenotype by promoting cell cycle progression, resistance to apoptotic stimuli, neo-vascularisation and tumour cell motility, invasiveness and metastasis. With these GTPases contributing at so many levels, they are appealing targets for the development of cancer chemotherapeutic agents.

Synergistic cytotoxic effects of zoledronic acid and radiation in human prostate cancer and myeloma cell lines

PURPOSE

The clinical use of the potent bisphosphonate zoledronic acid has increased recently, especially for the treatment of bone metastases. Synergistic effects with chemotherapeutic agents (e.g., doxorubicin, paclitaxel) have been shown. It is not known whether similar synergistic effects exist with radiation.

METHODS AND MATERIALS

IM-9 myeloma cells and C4-2 prostate cancer cells were treated with up to 200 microM concentrations of zoledronic acid, irradiated with single doses of up to 1,000 cGy, or exposed to combinations of both treatments. Cell viability was then determined via yellow dye 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assay and the affected fractions analyzed using the median effect principal, a method developed and validated by Chou and Talalay.

RESULTS

A statistically significant synergistic cytotoxic effect of the combination of zoledronic acid and radiation was documented. The extent of the effect was cell type-dependent, with the C4-2 cells showing a greater synergistic effect than the IM-9 cells.

CONCLUSIONS

The combined use of zoledronic acid and radiotherapy shows enhanced in vitro cytotoxicity for two human prostate and myeloma cancer cell lines over that expected for a simple additive effect from each treatment alone. A clinical trial is under way to test this combination therapy.

Bone cancer pain: the effects of the bisphosphonate alendronate on pain, skeletal remodeling, tumor growth and tumor necrosis

Patients with metastatic breast, lung or prostate cancer frequently have significant bone cancer pain. In the present report we address, in a single in vivo mouse model, the effects the bisphosphonate alendronate has on bone cancer pain, bone remodeling and tumor growth and necrosis. Following injection and confinement of green fluorescent protein-transfected murine osteolytic tumor cells into the marrow space of the femur of male C3H/HeJ mice, alendronate was administered chronically from the time the tumor was established until the bone cancer pain became severe. Alendronate therapy reduced ongoing and movement-evoked bone cancer pain, bone destruction and the destruction of sensory nerve fibers that innervate the bone. Whereas, alendronate treatment did not change viable tumor burden, both tumor growth and tumor necrosis increased. These data emphasize that it is essential to utilize a model where pain, skeletal remodeling and tumor growth can be simultaneously assessed, as each of these can significantly impact patient quality of life and survival.

Bone cancer pain model in mice: evaluation of pain behavior, bone destruction and morphine sensitivity

The primary aim of the study was to correlate pain development during bone cancer growth with objectively obtained tumor-induced changes in bone morphology. Additionally morphine sensitivity of this bone pain was evaluated. Mice were injected into the femur with osteolytic NCTC2472 cells, and behaviorally followed during a 3-week period. During the observation period increasing pain behavior was observed in tumor-bearing animals. Tumor mice exhibited spontaneous and movement-evoked lifting, the latter evoked through non-noxious palpation of the tumor. Limb use during forced ambulation on a rotarod decreased to substantial non-use of the affected limb by day 23. On day 23, micro-computer tomography scans of the tumor-bearing bones were evaluated for bone destruction. Different bone parameters indicative of osteolysis or fragmentation were significantly correlated with pain behavior. In a separate group of mice the effects of different morphine doses on pain behavior were evaluated on days 17 and 21 of tumor growth. Spontaneous lifting and movement-evoked lifting were sensitive to morphine treatment, although stress-induced analgesia due to repeated restraint might minimize movement-evoked lifting in mice. Limb use during forced ambulation was only slightly ameliorated by high morphine doses.

Anti-hyperalgesic activity of the cox-2 inhibitor lumiracoxib in a model of bone cancer pain in the rat

Chronic pain resulting from metastatic bone cancer remains poorly understood and resistant to treatment. Here we have examined the effect of the novel COX-2 enzyme inhibitor lumiracoxib in a model of bone cancer pain in the rat. Lumiracoxib was administered orally twice daily from day 10 to day 20 after injection of MRMT-1 tumour cells into one tibia. Mechanical hyperalgesia, measured as the reduction in weight-bearing of the ipsilateral limb, and the development of static and dynamic allodynia were significantly inhibited by repeated lumaricoxib administration. A similar reduction in hyperalgesia and allodynia was noted after twice daily administration of another COX-2 inhibitor, valdecoxib, whilst a single acute administration of either drug on day 20, produced no anti-nociceptive activity. Bone mineral density measurements, radiological scores and histological analysis showed that chronic lumaricoxib treatment also significantly attenuated bone destruction induced by tumour cell injection. These data indicate that lumiracoxib and other COX-2 inhibitors have potential therapeutic benefit in the treatment of bone cancer pain.

Zoledronic acid: A new parenteral bisphosphonate

BACKGROUND

Inhibition of bone resorption using bisphosphonates is an important step in palliation of complications of advanced cancer, such as hypercalcemia and metastatic bone disease.

OBJECTIVE

The goal of this article was to describe the pharmacologic properties of zoledronic acid (zoledronate) and discuss findings from preclinical and clinical studies of its use in skeletal disorders.

METHODS

Relevant English-language literature was identified using the terms zoledronic acid, zoledronate, Zometa, and 118072-93-8 through searches of MEDLINE (1966-June 2003) and International Pharmaceutical Abstracts (1970-June 2003), and abstract proceedings from the American Society of Clinical Oncology (1997-2002).

RESULTS

Zoledronic acid is a nitrogen-containing bisphosphonate that inhibits bone resorption. It is indicated for the treatment of hypercalcemia of malignancy and for the treatment of patients with multiple myeloma or documented metastasis from solid tumors, in conjunction with standard antineoplastic therapy. The recommended dosage is 4 mg via IV over >or= 15 minutes every 3 or 4 weeks. Compared with pamidronate 90 mg, zoledronic acid 4 and 8 mg provided a higher complete response rate for hypercalcemia of malignancy by day 10 (88.4% and 86.7% vs 69.7%; P = 0.002 and P = 0.015) and longer duration of action (median time to relapse, 30 and 40 days vs 17 days; P = 0.001 and P = 0.007). In patients with breast cancer or multiple myeloma, zoledronic acid was as effective as pamidronate in delaying time to a first skeletal-related event (373 days vs 363 days). In patients with hormone-refractory prostate cancer and bone metastases, zoledronic acid 4 mg reduced the proportion of patients who experienced a skeletal-related event (33% vs 44% with placebo; P = 0.021) or a skeletal fracture (13% vs 22% with placebo; P = 0.015). In patients with bone metastases from solid tumors, zoledronic acid delayed the median time to a first skeletal-related event (230 days vs 163 days with placebo; P = 0.023). Common adverse events include fever, nausea, constipation, fatigue, and bone pain.

CONCLUSION

Zoledronic acid is an effective and generally well-tolerated treatment for hypercalcemia of malignancy and skeletal complications of metastatic bone disease.

Animal and cellular models of chronic pain

Chronic pain, especially neuropathic pain and cancer pain, is often not adequately treated by currently available analgesics. Animal models provide pivotal systems for preclinical study of pain. This article reviews some of the most widely used or promising new models for chronic pain. Partial spinal ligation, chronic constriction injury, and L5/L6 spinal nerve ligation represent three of the best characterized rodent models of peripheral neuropathy. Recently, several mouse and rat bone cancer pain models have been reported. Primary or permanent cultures of sensory neurons have been established to study the molecular mechanism of pain, especially for neurotransmitter release and signal transduction. The emerging gene microarray, genomics and proteomics methods may be applied to throughly characterize these cells. Each model is uniquely created with distinct mechanisms, it is therefore essential to report and interpret results in the context of a specific model.