Bisphosphonates in the treatment of skeletal metastases

Recent Advances in Nanomedicine for the Diagnosis and Treatment of Prostate Cancer Bone Metastasis

Patients with advanced prostate cancer can develop painful and debilitating bone metastases. Currently available interventions for prostate cancer bone metastases, including chemotherapy, bisphosphonates, and radiopharmaceuticals, are only palliative. They can relieve pain, reduce complications (e.g., bone fractures), and improve quality of life, but they do not significantly improve survival times. Therefore, additional strategies to enhance the diagnosis and treatment of prostate cancer bone metastases are needed. Nanotechnology is a versatile platform that has been used to increase the specificity and therapeutic efficacy of various treatments for prostate cancer bone metastases. In this review, we summarize preclinical research that utilizes nanotechnology to develop novel diagnostic imaging tools, translational models, and therapies to combat prostate cancer bone metastases.

Zoledronic Acid Inhibits the RhoA-mediated Amoeboid Motility of Prostate Cancer Cells

BACKGROUND

The bisphosphonate Zoledronic acid (ZA) is a potent osteoclast inhibitor currently used in the clinic to reduce osteoporosis and cancer-induced osteolysis. Moreover, ZA exerts an anti-tumor effect in several tumors. Despite this evidence, the relevance of ZA in prostate cancer (PCa) is not completely understood.

OBJECTIVE

To investigate the effect of ZA administration on the invasive properties of PC3 cells, which are characterised by RhoA-dependent amoeboid motility.

METHODS

The effect of ZA administration on the in vitro invasive properties of PC3 cells was evaluated by cell migration in 3D collagen matrices, immunofluorescence and Boyden assays or transendothelial migration. Lung retention and colonization assays were performed to assess the efficacy of ZA administration in vivo.

RESULTS

PC3 cells are characterised by RhoA-dependent amoeboid motility. We now report a clear inhibition of in vitro PC3 cell invasion and RhoA activity upon ZA treatment. Moreover, to confirm a specific role of ZA in the inhibition of amoeboid motility of PC3 cells, we demonstrate that ZA interferes only partially with PC3 cells showing a mesenchymal phenotype due to both treatment with conditioned medium of cancer associated fibroblasts or to the acquisition of chemoresistance. Furthermore, we demonstrate that ZA impairs adhesion to endothelial cells and the trans-endothelial cell migration, two essential properties characterising amoeboid motility and PC3 metastatic dissemination. In vivo experiments prove the ability of ZA to inhibit the metastatic process of PC3 cells as shown by the decrease in lung colonization.

CONCLUSION

This study demonstrates that ZA inhibits Rho-dependent amoeboid motility of PC3 cells, thus suggesting ZA as a potential therapy to impede the metastatic dissemination of PC3 cells.

A pilot study of zoledronic acid in the treatment of patients with advanced malignant pleural mesothelioma

Purpose

Malignant pleural mesothelioma (MPM) is a rare malignancy with a dismal median survival of <12 months with current therapy. Single and combination chemotherapy regimens have shown only modest clinical benefit. In preclinical studies, nitrogen-containing bisphosphonates (zoledronic acid) inhibit growth of mesothelioma cells by different mechanisms: inhibition of mevalonate pathway, inhibition of angiogenesis, activation of apoptosis through caspase activation, and alteration in activity of matrix metalloproteinases, thereby affecting invasiveness of cancer cells.

Patients and methods

We investigated the role of zoledronic acid in a pilot, single-arm trial of MPM patients with Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0–2 who had progressed on prior treatments or had not received systemic therapy due to poor PS. Primary end point was composite response rate by modified response evaluation criteria in solid tumors and/or metabolic response by 2-deoxy-2-[fluorine-18]fluoro-d-glucose (¹⁸F-FDG) positron emission tomography criteria. Secondary end points were progression-free survival (PFS) and overall survival (OS). Exploratory end points include the effect of zoledronic acid therapy on vascular endothelial growth factor (VEGF), basic fibroblast growth factor, interleukin 8, transforming growth factor beta, mesothelin, and osteopontin levels.

Results

Eight male patients (median age of 62 years) with the following clinical characteristics were treated; ECOG PS was 0–2, 75% with epithelioid type, and 62% had prior chemotherapy Overall composite response rate was 12.5% and the clinical benefit rate (response + stable disease) was 37.5%. Median PFS was 2 months (0.5–21 months) and median OS was 7 months (0.8–28 months). No treatment-related toxicities were observed. Lower VEGF levels were predictive of favorable response and mesothelin levels correlated with disease course.

Conclusion

Zoledronic acid shows modest clinical activity without significant toxicity in patients with advanced MPM.

Osteonecrosis of the Jaws and Bisphosphonate Therapy

Bisphosphonates are a class of agents used to treat osteoporosis and malignant bone metastases. The efficacy of these agents in treating and preventing the significant skeletal complications associated with these conditions has had a major positive impact for patients and is responsible for their widespread use in medicine. Despite these benefits, osteonecrosis of the jaws has recently emerged as a significant complication in a subset of patients receiving these drugs. Based on a growing number of case reports and institutional reviews, bisphosphonate therapy may cause exposed and necrotic bone that is isolated to the jaw. This complication usually presents following simple dento-alveolar surgery, and can cause a significant adverse effect on the quality of life for most patients. The pathogenesis for this complication appears to be related to the profound inhibition of osteoclast function and bone remodeling.

Role of intravenous dosage regimens of bisphosphonates in relation to other aetiological factors in the development of osteonecrosis of the jaws in patients with myeloma

The aim of this case-control study was to identify possible explanatory risk factors for the development of bisphosphonate-related osteonecrosis of the jaws (BRONJ) by estimating the effects of intravenous dosage regimens of bisphosphonates, coexisting diseases, and other drugs on 201 patients with multiple myeloma, with or without BRONJ. We compared sex, treatment with bisphosphonates, incidence of diabetes, and the taking of drugs such as corticosteroids and chemotherapy in patients who had BRONJ (n=44) and patients who did not (n=157). Among the bisphosphonates given intravenously zoledronic acid showed a stronger correlation with BRONJ than pamidronic acid. The risk of developing BRONJ increased dramatically at cumulative intravenous doses of more than 78 mg of zoledronic acid or 600 mg of pamidronic acid, which corresponds to treatment for 18 months or longer. Diabetes mellitus correlated significantly with the development of BRONJ (p=0.01) while there was no correlation with sex, simultaneous treatment with corticosteroids, or chemotherapy. In conclusion, treatment with zoledronic acid, high doses of pamidronic acid, and the coexistence of diabetes mellitus seem to be associated with the development of BRONJ.

Efficacy and Safety of Zoledronic Acid and Pamidronate Disodium in the Treatment of Malignant Skeletal Metastasis: A Meta-Analysis

Solid tumors frequently metastasize to bone. Two bisphosphonates have been investigated for bone metastases including pamidronate disodium and zoledronic acid.By searching the PubMed, Embase, Wanfang, and China National Knowledge Infrastructure (CNKI) databases, we conducted a meta-analysis to determine the efficacy and safety of zoledronic acid compared with pamidronate disodium in reducing pain in patients with bone metastases.Studies were pooled, and the relative risk (RR) and its corresponding 95 % confidence interval (CI) were calculated. Version 12.0 STATA software was used for statistical analysis. Twenty relevant articles were included for this meta-analysis study.The complete response rate in cancer patients treatment with zoledronic acid was significantly higher than that with pamidronate disodium (relative risk [RR] = 1.32 [95% confidence interval (CI), 1.00-1.75]; P = 0.987, I = 0%). However, there was no significant difference in the rate of partial response rate (RR = 1.04, 95% CI: 0.90-1.20; P = 0.942, I = 0%) and in the total effective rate (RR = 1.06, 95% CI: 1.00-1.12; P = 0.998, I = 0%). For adverse events (AE), the incidence of headache in cancer patients with zoledronic acid was significantly lower than that with pamidronate disodium (RR = 0.82, 95% CI: 0.70-0.96; P = 0.793, I = 0%). There was no significant difference in nausea or vomiting (RR = 1.00, 95% CI: 0.92-1.09; P = 0.494, I = 0%), fever (RR = 0.98, 95% CI: 0.85-1.14; P =0.633, I = 0%), fatigue (RR = 1.01, 95% CI: 0.91-1.11; P = 0.914, I = 0%) and anorexia (RR = 1.31, 95% CI: 0.91-1.87; P = 0.024, I = 64.4%).In conclusion, this meta-analysis indicates that treatment with zoledronic acid was more effective than pamidronate disodium in the complete response assessments and the incidence of headache, an AE, was significantly lower in cancer patients with zoledronic acid.

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.

Bisphosphonate-related osteonecrosis of the jaw: an overview

Bisphosphonates are widely used in the management of metastatic disease to bone and in diseases of altered bone turnover. Recently, multiple-case series and retrospective studies have established a relationship between necrotic bone lesions localized to the jaw and the use of chronic bisphosphonate therapy. This condition has been named bisphosphonate-related osteonecrosis of the jaw (BRONJ). To evaluate the potential risks associated with this new and emerging complication, stage-specific management strategies and guidelines have been developed. In view of the widespread use of chronic bisphosphonate therapy, the observation of an associated risk of osteonecrosis of the jaw should alert practitioners to monitor for this previously unrecognized complication and to reevaluate the indications for and the duration of bisphosphonate therapy in patients with osteopenia/osteoporosis and cancer. Morbidity associated with BRONJ might be prevented or reduced by implementing prevention strategies and establishing early diagnostic procedures. The current widespread use of bisphosphonates as an inhibitor of bone resorption is directly attributable to their efficacy in improving the quality of life for patients with metastatic bone cancer, osteoporosis, and Paget's disease.

Multiple myeloma

Advances in the imaging and treatment of multiple myeloma have occurred over the past decade. This article summarises the current status and highlights how an understanding of both is necessary for optimum management.

Modifications to the dNTP triphosphate moiety: from mechanistic probes for DNA polymerases to antiviral and anti-cancer drug design

Abnormal replication of DNA is associated with many important human diseases, most notably viral infections and neoplasms. Existing approaches to chemotherapeutics for diseases associated with dysfunctional DNA replication classically involve nucleoside analogues that inhibit polymerase activity due to modification in the nucleobase and/or ribose moieties. These compounds must undergo multiple phosphorylation steps in vivo, converting them into triphosphosphates, in order to inhibit their targeted DNA polymerase. Nucleotide monophosphonates enable bypassing the initial phosphorylation step at the cost of decreased bioavailability. Relatively little attention has been paid to higher nucleotides (corresponding to the natural di- and triphosphate DNA polymerase substrates) as drug platforms due to their expected poor deliverability. However, a better understanding of DNA polymerase mechanism and fidelity dependence on the triphosphate moiety is beginning to emerge, aided by systematic incorporation into this group of substituted methylenebisphosphonate probes. Meanwhile, other bridging, as well as non-bridging, modifications have revealed intriguing possibilities for new drug design. We briefly survey some of this recent work, and argue that the potential of nucleotide-based drugs, and intriguing preliminary progress in this area, warrant acceptance of the challenges that they present with respect to bioavailability and metabolic stability.

Treatment of breast cancer with bone metastasis: bisphosphonate treatment - current and future

There are a variety of treatments for patients with bone metastases from breast cancer. These include bisphosphonates, antitumor endocrine and cytotoxic systemic therapies, radiotherapy to the metastatic site, radionucleotides, and conservative treatment (analgesics). The optimal combination treatment for bone metastases is not clear. Bisphosphonates are effective for reducing skeletal complications such as bone pain, pathological fracture, bone surgery, and hypercalcemia. Bisphosphonates are recommended as the gold standard therapy for breast cancer with bone metastases. Treatment guidelines tend to recommend starting a bisphosphonate at the time of diagnosis of bone metastases. Animal models have supported the prevention of bone metastasis by bisphosphonate therapy, but three major adjuvant clinical trials of the oral bisphosphonate clodronate have yielded conflicting results. However, our preliminary trial of an intravenous bisphosphonate, pamidronate, showed effective inhibition of bone metastases. The use of bisphosphonates, especially zoledronic acid, as adjuvant therapy is promising, but it is still investigational.

Apomine enhances the antitumor effects of lovastatin on myeloma cells by down-regulating 3-hydroxy-3-methylglutaryl-coenzyme A reductase

Apomine, a 1,1-bisphosphonate-ester with antitumor activity, has previously been reported to strongly down-regulate 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase), the rate-limiting enzyme in the mevalonate pathway responsible for the prenylation of proteins. Here, we show that although apomine down-regulated HMG-CoA reductase protein levels in myeloma cells, it did not inhibit protein prenylation, and apomine-induced apoptosis could not be prevented by mevalonate, indicating that apomine cytotoxicity is independent from its effects on HMG-CoA reductase. Instead, apomine cytotoxicity was prevented by the addition of phosphatidylcholine, which is similar to the previously reported ability of phosphatidylcholine to overcome the cytotoxicity of farnesol, whereas phosphatidylcholine had no effect on down-regulation of HMG-CoA reductase by apomine. These findings raised the possibility that apomine, independent from its own cytotoxic effects, could enhance the antitumor effects of the competitive HMG-CoA reductase inhibitor lovastatin via down-regulating HMG-CoA reductase. Indeed, treatment with apomine in combination with lovastatin resulted in synergistic decreases in viable cell number and induction of apoptosis. At the concentrations used, apomine down-regulated HMG-CoA reductase protein levels without being cytotoxic. Accumulation of unprenylated Rap1A by lovastatin was enhanced in the presence of apomine. Furthermore, synergy was completely prevented by mevalonate, and apomine did not synergize with desoxolovastatin, which does not inhibit HMG-CoA reductase. We conclude that the synergistic drug interaction results from an enhancement by apomine of the effects of lovastatin, mediated by down-regulation of HMG-CoA reductase by apomine. Thus, these findings demonstrate a novel strategy for enhancing the antitumor effects of lovastatin.

Inhibition of the mevalonate pathway and activation of p38 MAP kinase are independently regulated by nitrogen-containing bisphosphonates in breast cancer cells

Bisphosphonates are widely used inhibitors of bone resorption. They also inhibit the growth of various cancer cells in vitro, but the clinical significance of this effect is unclear. The cancer growth inhibitory effects of nitrogen-containing bisphosphonates, (i.e. zoledronate) have been attributed to their ability to inhibit the mevalonate pathway. We have shown that bisphosphonates also induce p38 activation, which signals resistance against the drug-induced growth inhibition through an unknown mechanism. We show here that zoledronate induces a G1/S cell cycle arrest in human MDA-MB-231 breast cancer cells. Furthermore, p38 inhibitor augments bisphosphonate-induced growth inhibition by inducing an additional G2-phase cell cycle arrest. We also show that the nitrogen-containing bisphosphonate-induced effects on p38 phosphorylation occur before accumulation of unprenylated Rap1A or Rac1 activation. Geranylgeranyl pyrophosphate, an end-product of the mevalonate pathway, reversed the accumulation of unprenylated Rap1A but not phosphorylation of p38. Geranylgeranyl pyrophosphate also reversed n-BP induced growth inhibition, but the completeness of this reversal was nitrogen-containing bisphosphonate concentration dependent. Also mevastatin induced the accumulation of unprenylated Rap1A, but it did not induce p38 phosphorylation. In conclusion, our results suggest that in addition to the previously reported effects on apoptosis, nitrogen-containing bisphosphonates also inhibit the growth of MDA-MB-231 breast cancer cells by inducing G1/S cell cycle arrest. The bisphosphonate-induced p38 activation signals for resistance against these drugs, by promoting progression through the G2/M-checkpoint. Of these pathways only growth inhibition is mediated via inhibition of the mevalonate pathway in MDA-MB-231 cells. Combining p38 inhibitors with bisphosphonates may result in increased anti-cancer efficacy.

The bisphosphonate olpadronate inhibits skeletal prostate cancer progression in a green fluorescent protein nude mouse model

PURPOSE

Metastatic bone disease is one of the major causes of morbidity and mortality in prostate cancer patients. Bisphosphonates are currently used to inhibit bone resorption and reduce tumor-induced skeletal complications. More effective bisphosphonates would enhance their clinical value.

EXPERIMENTAL DESIGN

We tested several bisphosphonates in a green fluorescent protein (GFP)-expressing human prostate cancer nude mouse model. The in vivo effects of four bisphosphonates, including pamidronate, etidronic acid, and olpadronate, on bone tumor burden in mice intratibially inoculated with PC-3-GFP human prostate cancer cells were visualized by whole-body fluorescence imaging and X-ray.

RESULTS

The PC-3-GFP cells produced extensive bone lesions when injected into the tibia of immunocompromised mice. The skeletal progression of the PC-3-GFP cell growth was monitored by GFP fluorescence and the bone destruction was evaluated by X-ray. We showed that 3,3-dimethylaminopropane-1-hydroxy-1,1-diphosphonic acid (olpadronate) was the most effective bisphosphonate treatment in reducing tumor burden as assessed by GFP imaging and radiography. The GFP tumor area and X-ray score significantly correlated. Reduced tumor growth in the bone was accompanied by reduced serum calcium, parathyroid hormone-related protein, and osteoprotegerin.

CONCLUSIONS

The serum calcium, parathyroid hormone-related protein, and osteoprotegerin levels were significantly correlated with GFP area and X-ray scores. Treatment with olpadronate reduced tumor growth in the bone measured by GFP and X-ray imaging procedures. Imaging of GFP expression enables monitoring of tumor growth in the bone and the GFP results complement the X-ray assessment of bone disease. The data in this report suggest that olpadronate has potential as an effective inhibitor of the skeletal progression of clinical prostate cancer.

Ibandronate, an experimental intravenous bisphosphonate for osteoporosis, bone metastases, and hypercalcemia of malignancy

Ibandronate is an experimental intravenous bisphosphonate under study for the prevention or treatment of osteoporosis and skeletal complications of bone metastases, as well as hypercalcemia of malignancy. To review the data on this drug, PubMed/MEDLINE was searched for pertinent studies in English; data from January 1986-October 2005 were reviewed. In preclinical studies, ibandronate was an extremely potent bisphosphonate compared with its predecessors and was active in all animal models of human postmenopausal and corticosteroid-associated osteoporosis. Similar to other bisphosphonates, ibandronate exhibits antitumor activity and prevents or reduces bone metastases. Forty to fifty percent of the dose is bound to bone; renal clearance of unchanged drug accounts for 70% of total body clearance. Early clinical trials demonstrated efficacy and tolerability of intravenous ibandronate in the prevention or treatment of postmenopausal and corticosteroid-associated osteoporosis when administered once every 3 months. Intravenous ibandronate also reduces skeletal complications of bone metastases, including pain, although the cumulative dose used is much higher than that used in osteoporosis, as the drug is administered every 3-4 weeks. Single doses of intravenous ibandronate are probably also effective in the treatment of hypercalcemia of malignancy. The major tolerability issue with intravenous bisphosphonates is renal safety, thus the drugs generally require infusion (e.g., 0.25 hr for zoledronic acid, 2-24 hrs for pamidronate). However, intravenous ibandronate can be administered by bolus injection over a few minutes without an elevated risk of nephrotoxicity. The experimental intravenous dosage is 2 mg every 3 months for treatment or prevention of osteoporosis, and 2-6 mg every 3-4 weeks or in a single dose for treatment of bone metastases or hypercalcemia of malignancy, respectively. Ibandronate can be used in the presence of severe renal impairment with proper dosage adjustment. The drug will be an interesting addition to the available drugs for osteoporosis, bone metastases, and hypercalcemia of malignancy. Studies of intravenous ibandronate as an adjunctive treatment for cancers that tend to metastasize to bone are under way. Whether intravenous ibandronate will be a therapeutic advance is best answered by randomized, controlled trials. These are ongoing and should provide data with which to make better-informed choices concerning intravenous bisphosphonates.

Ibandronate: a new oral bisphosphonate for postmenopausal osteoporosis

OBJECTIVE

To review a new oral bisphosphonate, ibandronate, recently approved by the U.S. Food and Drug Administration for the treatment and prevention of postmenopausal osteoporosis.

DATA SOURCE

A MEDLINE/PUBMED search was conducted to identify pertinent studies in the English language. Additional references were obtained from the bibliographies of these studies. Data over the time period of 1986 through July 2005 were reviewed.

STUDY SELECTION AND DATA EXTRACTION

All studies evaluating any aspect of ibandronate in animals and humans. Studies in humans focused on the oral drug formulation.

DATA SYNTHESIS

Preclinical studies established that ibandronate was an extremely potent bisphosphonate compared with its predecessors and that it was active in all animal models of human postmenopausal and corticosteroid-associated osteoporosis. Similar to other selected bisphosphonates, preclinical studies also showed that ibandronate exhibits antitumor activity and prevents and/or reduces bone metastases. As with other oral bisphosphonates, oral bioavailability is very poor (less than 1%) and substantially reduced by administration with or proximal to cations (e.g., food, antacids, mineral supplements). Clinical trials have demonstrated the efficacy and tolerability of oral ibandronate in the treatment and prevention of postmenopausal osteoporosis when administered once daily, once weekly, and even once monthly. Ibandronate also reduces the skeletal complications of bone metastases in patients with cancer, including pain, although the dosage used is much higher than that used in osteoporosis. As with other bisphosphonates, the major tolerability issue with ibandronate is upper gastrointestinal (GI) distress (dyspepsia, pain, esophagitis, esophageal and gastric ulcers). The dosage regimen for the treatment or prevention of postmenopausal osteoporosis (the only currently approved use in the United States) is 2.5 mg once a day or 150 mg once monthly (on the same date each month). Ibandronate should not be used in the presence of severe renal impairment (creatinine clearance below 30 mL/min). The usual complex administration instructions for other oral bisphosphonates apply to ibandronate as well.

CONCLUSION

Oral ibandronate is an interesting addition to the therapeutic armamentarium for osteoporosis and cancer metastatic to bone. In fact, studies of ibandronate as an adjunctive treatment for cancers with a predilection to metastasize to bone are under way. Ibandronate has taken advantage of a complex pharmacodynamic profile in which its antiresorptive activity is independent of the frequency of dosing provided that a minimum dose-per-unit time is exceeded. Studies with every three-month dosing (and even less frequently) are under way. Whether or not the less frequent dosing of oral ibandronate will translate into a therapeutic advantage over older oral agents such as alendronate and risedronate is open to speculation. This is a difficult question to answer in the absence of head-to-head randomized controlled trials (RCTs). Older agents are still preferred until RCTs demonstrate that ibandronate is as safe and effective as these older agents.

Bisphosphonates Inhibit the Growth of Mesothelioma Cells In vitro and In vivo

PURPOSE

Bisphosphonates (such as risedronate and zoledronate) are widely used inhibitors of bone resorption. Despite their in vitro antiproliferative effects in various cancer cells, bisphosphonates have not exhibited significant antitumor efficacy in animal models of visceral cancer, which may be due to their poor bioavailability. The diagnostic use of radioactive bisphosphonates has revealed the accumulation of bisphosphonates in mesothelioma, which prompted us to test the antitumor efficacy of bisphosphonates in this disease.

EXPERIMENTAL DESIGN AND RESULTS

Treatment with either risedronate or zoledronate (2 x 10(-4) to 2 x 10(-6) mol/L) inhibited the growth of AB12 and AC29 mouse mesothelioma cells and induced the accumulation of unprenylated Rap1A in these cells. Both these in vitro effects were reversed by geranygeraniol, an end product of the mevalonate pathway that these bisphosphonates inhibit. Both bisphosphonates also induced the phosphorylation of the p38 mitogen-activated protein kinase in AB12 and AC29 cells. The inhibition of p38 augmented bisphosphonate-induced growth inhibition in these cells. Bisphosphonate-induced p38 phosphorylation was not reversible by geranylgeraniol. Risedronate (15 mg/kg) and zoledronate (0.5 mg/kg) inhibited the growth of s.c. tumors and increased the median survival of mice with i.p. mesothelioma tumors in vivo.

DISCUSSION

In conclusion, risedronate and zoledronate inhibit the mevalonate pathway and induce p38 activation in mesothelioma cells in vitro. The effects on the mevalonate pathway dominate because the net result is growth inhibition. Both bisphosphonates also inhibit mesothelioma tumor growth in vivo and prolong the survival of mesothelioma-bearing mice. These results support further study of bisphosphonates in the management of mesothelioma.

Recent advances in MMP inhibitor design

The search for an MMP inhibitor with anticancer efficacy is a nearly three-decade endeavor. This inhibitor is yet to be found. The reasons for this failure include shortcomings in the chemistry of these compounds (including broad MMP sub-type selectivity, metabolic lability, and toxicity) as well as the emerging, and arguably extraordinary, complexity of MMP cell (and cancer) biology. Together these suggest that the successful anticancer inhibitor must possess MMP selectivity against the MMP subtype whose involvement is critical, yet highly temporally (with respect to metastatic progression) and mechanistically (with respect to matrix degradation) regulated. This review summarizes the progression of chemical structure and mechanistic thinking toward these objectives, with emphasis on the disappointment, the perseverance, and the resilient optimism that such an inhibitor is there to be discovered.

The use of bisphosphonates in palliative treatment of bone metastases in a terminally ill, oncological elderly population

According to the guidelines of WHO [WHO, 1999. Cancer Pain and Palliative Care Program. Cancer Pain Release, vol. 13], the term terminally ill patient refers to oncological patients whose life expectancy is lower than 90 days, and the index of their physical state (defined as the Karnofsky Index) is below 50. The terminally ill oncological patients are treatable with the palliative cures, representing a treatment system aimed at improving the quality of life (QOL) of both the patient and the family members, decreasing the physical and psychical sufferance of the patient. The present study followed 35 terminally ill oncological patients with bone metastases, at their homes, for the University of Catania. These patients had previously been followed by the Local Sanitary Unit (ASL 3) of Catania, and established a life expectancy not longer than 3 months. Independently from the basic neoplastic disease resulting in the bone metastases, all the patients were treated with sodium clodronate (SC) intravenously, 300 mg every second day, in order to decrease the bone pains. The visual analogue scale (VAS) for pain relief, the autonomy (IADL) and autosufficiency (ADL, Barthel Index) were evaluated after 1, 3, and 6 months of treatment. The results indicate an overall significant improvement both in the pain symptoms and the QOL. Also the compromised autonomy and autosufficiency of this population seemed to be improved, at least as compared to the predicted and expected results at the start of this trial, and also compared to the relevant literature. One can conclude that the i.v. application of 300 mg of SC every other day produced a significant pain reduction and improved the QOL, and helped in maintaining the actual autonomy and autosufficiency. On this basis we suggest the use of this compound in the given type of terminally ill patients.

Problems monitoring response in multiple myeloma

There has been a revolution in the treatment of multiple myeloma over the past decade. This article seeks to correlate advances in imaging with advances in treatment and to highlight how proper understanding of both is necessary for optimum management.

Ibandronate: efficacy in the treatment of metastatic bone disease

Ibandronate is a bisphosphonate treatment for metastatic bone disease. In Phase III trials in breast cancer patients, intravenous and oral formulations of ibandronate lowered the incidence of skeletal-related events, reduced metastatic bone pain scores throughout 2 years of treatment, and had significant positive effects on patient quality of life, demonstrating its efficacy in this condition. Recent pilot studies in other primary cancers suggest that a loading dose of ibandronate may relieve severe or opioid-resistant metastatic bone pain. In safety analyses, ibandronate was well tolerated with a safety profile comparable to placebo. Ibandronate therefore represents a treatment choice with documented efficacy and safety in metastatic bone disease from breast cancer.

Endocrine tumours of the gastrointestinal tract: Chemotherapy

Malignant neuroendocrine tumours are less sensitive to chemotherapy than other epithelial malignancies. If chemotherapy is considered, tumours of pancreatic origin have a higher sensitivity than tumours from the gastrointestinal tract ('carcinoids'). Chemotherapy with streptozocin combinations and with dacarbazine should be considered in patients with progressive malignant neuroendocrine tumours of the pancreas. A favourable response to chemotherapy can be expected in up to 60% of patients receiving a combination of streptozocin plus doxorubicin, and in up to 40% of patients receiving dacarbazine. A survival benefit has been shown for streptozocin combinations. Treatment regimens are effective in functioning and non-functioning tumours. The response to treatment cannot be predicted. Poorly differentiated neuroendocrine tumours, independent of their origin, respond to a combination of etoposide plus cisplatin. Chemotherapy is, however, almost ineffective in patients with well-differentiated neuroendocrine tumours originating in the gastrointestinal tract ('carcinoids').