A newly developed bisphosphonate, YM529, is a potent apoptosis inducer of human myeloma cells

Inhibition of Arenaviridae nucleoprotein exonuclease by bisphosphonate

Arenaviruses are emerging enveloped negative-sense RNA viruses that cause neurological and hemorrhagic diseases in humans. Currently, no FDA-approved vaccine or therapeutic agent is available except for ribavirin, which must be administered early during infection for optimum efficacy. A hallmark of arenavirus infection is rapid and efficient immune suppression mediated by the exonuclease domain encoded by the nucleoprotein. This exonuclease is therefore an attractive target for the design of novel antiviral drugs since exonuclease inhibitors might not only have a direct effect on the enzyme but could also boost viral clearance through stimulation of the innate immune system of the host cell. Here, in silico screening and an enzymatic assay were used to identify a novel, specific but weak inhibitor of the arenavirus exonuclease, with IC50 values of 65.9 and 68.6 µM for Mopeia virus and Lymphocytic choriomeningitis virus, respectively. This finding was further characterized using crystallographic and docking approaches. This study serves as a proof of concept and may have assigned a new therapeutic purpose for the bisphosphonate family, therefore paving the way for the development of inhibitors against Arenaviridae.

Effects of ranibizumab and zoledronic acid on endometriosis in a rat model

PURPOSE

To investigate the histological efficacy of ranibizumab and zoledronic acid in an experimentally induced endometriosis model as compared with danazol, buserelin acetate and dienogest.

METHODS

Endometrial implants were introduced in 52 female Wistar albino rats, which were then randomly divided into six groups. The animals were, respectively, given dienogest, danazol, buserelin acetate, zoledronic acid, ranibizumab and 0.9% NaCl. After 4 weeks, the volumes and histopathological properties of the implants were evaluated and the implants were excised completely at the third laparotomy. A histopathological scoring system was used to evaluate the preservation of epithelia. Endometrial explants were evaluated immunohistochemically.

RESULTS

Among the groups, the histological score was significantly lower in the zoledronic acid and ranibizumab groups compared with the controls (p < 0.001). There were no significant differences regarding ellipsoidal volume levels between groups (p > 0.05). However, there was a statistically significant difference regarding cell numbers according to the degree of Bcl-2, NF-κB, and CD31 staining (p < 0.001). There was no statistically significant difference in Bcl-2, CD31, or NF-κB staining in the binary comparisons between the other groups (p > 0.05). For Bcl-2 staining, the staining rate of the group treated with zoledronic acid was significantly lower compared with the dienogest and danazol groups (p < 0.05). The staining rates of CD31 and NF-κB were significantly lower in the zoledronic acid and ranibizumab groups compared with the controls (p < 0.05).

CONCLUSION

According to these results, zoledronic acid and ranibizumab may be putative candidates for the treatment of endometriosis.

Synthesis and biological evaluation of indolylglyoxylamide bisphosphonates, antimitotic microtubule-targeting derivatives of indibulin with improved aqueous solubility

Indibulin (D-24851) derivatives with bisphosphonate fragment connected to the N1 atom of imidazole ring were synthesized by alkylation of (indolyl-3)methylglyoxylates with ethylenebisphosphonate. Biological evaluation of targeted compounds 4a-d using the phenotypic sea urchin embryo assay provided evidence that replacing of p-chlorobenzene ring in indibulin by bisphosphonate group did not eliminate antimitotic microtubule destabilizing activity. The most active molecule, tetraacid 5a, at physiological pH formed tetrasodium salt 6a with aqueous solubility value of at least 10 mg/mL. Molecule 5a was more potent in the sea urchin embryo assay than the parent indibulin. This compound also exhibited pronounced cytotoxicity against A549 lung carcinoma and A375 melanoma cell lines.

Effects of canagliflozin on growth and metabolic reprograming in hepatocellular carcinoma cells: Multi-omics analysis of metabolomics and absolute quantification proteomics (iMPAQT)

Aim

Metabolic reprograming is crucial in the proliferation of hepatocellular carcinoma (HCC). Canagliflozin (CANA), a sodium-glucose cotransporter 2 (SGLT2) inhibitor, affects various metabolisms. We investigated the effects of CANA on proliferation and metabolic reprograming of HCC cell lines using multi-omics analysis of metabolomics and absolute quantification proteomics (iMPAQT).

Methods

The cells were counted 72 hours after treatment with CANA (10 μM; n = 5) or dimethyl sulfoxide (control [CON]; n = 5) in Hep3B and Huh7 cells. In Hep3B cells, metabolomics and iMPAQT were used to evaluate the levels of metabolites and metabolic enzymes in the CANA and CON groups (each n = 5) 48 hours after treatment.

Results

Seventy-two hours after treatment, the number of cells in the CANA group was significantly decreased compared to that in the CON group in Hep3B and Huh7 cells. On multi-omics analysis, there was a significant difference in the levels of 85 metabolites and 68 metabolic enzymes between the CANA and CON groups. For instance, CANA significantly downregulated ATP synthase F1 subunit alpha, a mitochondrial electron transport system protein (CON 297.28±20.63 vs. CANA 251.83±22.83 fmol/10 μg protein; P = 0.0183). CANA also significantly upregulated 3-hydroxybutyrate, a beta-oxidation metabolite (CON 530±14 vs. CANA 854±68 arbitrary units; P<0.001). Moreover, CANA significantly downregulated nucleoside diphosphate kinase 1 (CON 110.30±11.37 vs. CANA 89.14±8.39 fmol/10 μg protein; P = 0.0172).

Conclusions

We found that CANA suppressed the proliferation of HCC cells through alterations in mitochondrial oxidative phosphorylation metabolism, fatty acid metabolism, and purine and pyrimidine metabolism. Thus, CANA may suppress the proliferation of HCC by regulating metabolic reprograming.

Pre-clinical efficacy assessment of Malva sylvestris on chronic skin inflammation

In the search for improved quality of life, the treatment of skin diseases like psoriasis (hyperproliferative disease) is valid, since it causes huge social discomfort to the patient. In this context, earlier studies showed that Malva sylvestris L. has anti-inflammatory activity demonstrated by acute animal models of skin inflammation, becoming a promising target for further studies. The present investigation aimed to verify the effect of hydroalcoholic extract of M. sylvestris (HEMS) on the chronic inflammatory and hyperproliferative response caused by multiple applications of 12-O-tetradecanoylphorbol-13-acetate (TPA) on mouse ears. Topical application of HEMS reduced oedema, leukocyte migration (mono- and polymorphonuclear cells) and keratinocyte hyperproliferation, confirmed by histology and proliferating cell nuclear antigen (PCNA) immunostaining. It was found that the anti-inflammatory effects of the extract did not involve the glucocorticoid system, and its incubation with HaCaT keratinocytes caused low toxicity and reduced cell proliferation by apoptosis. Thus, HEMS proved to be effective as an anti-psoriatic therapy, with the ability to prevent keratinocyte hyperproliferation and with low toxicity by topical application.

The effect of alendronate on proteome of hepatocellular carcinoma cell lines

Cancer is a life threatening disorder effecting 11 million people worldwide annually. Among various types of cancers, Hepatocellular carcinoma (HCC) has a higher rate of mortality and is the fifth leading cause of cancer related deaths around the world. Many chemotherapeutic drugs have been used for the treatment of HCC with many side effects. These drugs are inhibitors of different cell regulatory pathways. Mevalonate (MVA) pathway is an important cellular cascade vital for cell growth. A variety of inhibitors of MVA pathway have been reported for their anticancerous activity. Bisphosphonates (BPs) are members of a family involved in the treatment of skeletal complications. In recent years, their anticancer potential has been highlighted. Current study focuses on exploring the effects of alendronate (ALN), a nitrogen containing BP, on hepatocellular carcinoma cell line using genomic and proteomics approach. Our results identified ten differentially expressed proteins, of which five were up regulated and five were down regulated in ALN treated cells. Furthermore, we also performed gene expression analysis in treated and control cell lines. The study may help in understanding the molecular mechanism involved in antitumor activity of ALN, identification of possible novel drug targets, and designing new therapeutic strategies for HCC.

Quality of life and supportive care in multiple myeloma

Multiple myeloma is the second most common haematological malignancy. Novel therapies have led to improvement in survival. Current myeloma management is matching the progress made in improved survival through disease control while optimising quality of life with effective supportive care. Supportive treatment is an essential part of the therapeutic management of myeloma patients because it is directed towards improving the patient’s quality of life and also can improve survival. The aim of this review is to highlight the relationship among life of quality, supportive care, and improvement in survival.

Conflict of interest:None declared.

Zoledronic acid exerts its antitumor effect in multiple myeloma interfering with the bone marrow microenvironment

Multiple myeloma (MM) is a B-cell malignancy characterized by an excess of monotypic plasma cells which localize almost exclusively in the bone marrow provoking bone destruction via the activation of the osteoclasts. The bone marrow microenvironment, mainly through stromal cells, is strictly involved in the evolution of the disease supporting MM cell growth and survival [1]. MM plasma cells reside in the bone marrow by binding to adhesion molecule of extracellular matrix (ECM) and stromal cells. The activation of some signaling pathways within the stromal cells increases the production of several cytokines which in turn favors the myeloma cell proliferation and survival [2-6], and enhance the drug resistance by anti-apoptotic mechanisms [1,7-9]. Novel therapeutic agents target not only the myeloma cells but also the interaction between MM cells and the bone marrow microenvironment [8]. Bisphosphonates (Bps) interfere as well with bone microenvironment inhibiting the survival of stromal cells and hampering the contact between plasma and stromal cells. In this review we will revise preclinical evidences, and the potential mechanisms of the antitumor activity of zoledronic acid.

The backbone of progress--preclinical studies and innovations with zoledronic acid

Bisphosphonates (BPs) are antiresorptive agents that block pathologic bone resorption by inhibiting osteoclast function and later inducing osteoclast apoptosis. These agents localize to bone and break the vicious cycle of bone resorption that results from cross-stimulation between cancer cells and the bone remodeling cells, thereby reducing cancer-induced osteolysis and the tumor burden in bone. Thus nitrogen-containing BPs (N-BPs) have well established clinical benefits in the treatment of bone metastases from solid tumors and bone lesions from multiple myeloma. Preclinical data indicate that N-BPs, especially zoledronic acid (ZOL), can exert antimyeloma activity both in vitro and in vivo. Studies show that N-BPs can inhibit multiple intracellular processes essential for cancer cell proliferation and invasion and induce apoptosis. Furthermore, clinically relevant doses of N-BPs inhibit tumor-associated angiogenesis and can modulate macrophage phenotype in vivo, which is likely to contribute to anticancer effects.

Supportive therapy in multiple myeloma

In this chapter we want to give an overview on various supportive measures, which help to prevent or to fight complications of multiple myeloma, improve patient wellbeing and increase safety of administration of specific anti-myeloma therapy.

Selective fluorescence sensing of deoxycytidine 5'-monophosphate (dCMP) employing a bis(diphenylphosphate)diimine ligand

A new bis(diphenylphosphate)diimine ligand (BP1) was prepared and evaluated for its ability for selective detection of deoxycytidine 5'-monophosphate (dCMP). BP1 exhibited off-type fluorescence in the presence of dCMP. The fluorescence of BP1 was significantly quenched upon the addition of 2.5 × 10(-4) M dCMP and the detection limit was 1.25 × 10(-5) M in MeCN-H(2)O (1:1, v/v). The binding ratio between BP1 and dCMP was determined to be 1:1 with the binding constant of 3.98 ± 0.60 × 10(-3) M(-1).

A promising approach for treatment of tumor-induced bone diseases: utilizing bisphosphonate derivatives of nucleoside antimetabolites

Despite palliative treatments, tumor-induced bone disease (TIBD) remains highly debilitating for many cancer patients and progression typically results in death within two years. Therefore, more effective therapies with enhanced anti-resorptive and cytotoxic characteristics are needed. We developed bisphosphonate-chemotherapeutic conjugates designed to bind bone and hydrolyze, releasing both compounds, thereby targeting both osteoclasts and tumor cells. This study examined the effects of our lead compound, MBC-11 (the anhydride formed between arabinocytidine (AraC)-5'-phosphate and etidronate), on bone tumor burden, bone volume, femur bone mineral density (BMD), and overall survival using two distinct mouse models of TIBD, the 4T1/luc breast cancer and the KAS-6/1-MIP1alpha multiple myeloma models. In mice orthotopically inoculated with 4T1/luc mouse mammary cells, MBC-11 (0.04 microg/day; s.c.) reduced the incidence of bone metastases to 40% (4/10), compared to 90% (9/10; p=0.057) and 100% (5/5; p=0.04) of PBS- or similarly-dosed, zoledronate-treated mice, respectively. MBC-11 also significantly decreased bone tumor burden compared to PBS- or zoledronate-treated mice (p=0.021, p=0.017, respectively). MBC-11 and zoledronate (0.04 microg/day) significantly increased bone volume by two- and four-fold, respectively, compared to PBS-treated mice (p=0.005, p<0.001, respectively). In mice systemically injected with human multiple myeloma KAS-6/1-MIP1alpha cells, 0.04 and 4.0 microg/day MBC-11 improved femur BMD by 13% and 16%, respectively, compared to PBS (p=0.025, p=0.017, respectively) at 10 weeks post-tumor cell injection and increased mean survival to 95 days compared to 77 days in mice treated with PBS (p=0.047). Similar doses of zoledronate also improved femur BMD (p< or =0.01 vs PBS) and increased mean survival to 86 days, but this was not significantly different than in PBS-treated mice (p=0.53). These results demonstrate that MBC-11 decreases bone tumor burden, maintains bone structure, and may increase overall survival, warranting further investigation as a treatment for TIBD.

Skeletal complications of prostate cancer: pathophysiology and therapeutic potential of bisphosphonates

Patients with prostate cancer are at risk for skeletal complications resulting from treatment-induced bone loss and for bone metastases. The therapeutic potential of zoledronic acid for the treatment of prostate cancer has been demonstrated in both preclinical and clinical studies. In patients receiving androgen-deprivation therapy, zoledronic acid increases bone mineral density, and, in patients with bone metastases, it reduces the incidence of skeletal complications. Preclinical studies have also demonstrated the antitumor potential of bisphosphonates. Specifically, zoledronic acid inhibits proliferation and induces apoptosis of human prostate cancer cell lines in vitro and has enhanced antitumor activity when combined with taxanes. Animal models have further shown that bisphosphonates decrease tumor-induced osteolysis and reduce skeletal tumor burden. In a model of prostate cancer, zoledronic acid significantly inhibited growth of both osteolytic and osteoblastic tumors and reduced circulating levels of prostate-specific antigen. These studies suggest that zoledronic acid has the potential to inhibit bone metastasis and bone lesion progression in patients with prostate cancer.

Nitrogen-containing bisphosphonate incadronate augments the inhibitory effect of farnesyl transferase inhibitor tipifarnib on the growth of fresh and cloned myeloma cellsin vitro

RAS gene mutations occur in 30 - 40% of multiple myeloma (MM) patients. Farnesylation is the first step in the post-translational modification of RAS proteins. Tipifarnib is a potent farnesyl transferase inhibitor, and incadronate prevents post-translational prenylation of GTP-binding proteins such as RAS proteins. We examined the effect of tipifarnib in combination with incadronate on the growth of fresh and cloned myeloma cells in vitro. Tipifarnib inhibited the growth of myeloma cells, and this inhibition was intensified when tipifarnib was combined with incadronate. Tipifarnib, in combination with incadronate, may have some benefits in MM patients.

A novel third generation bisphosphonate, minodronate (YM529), prevented proliferation and migration of hepatocellular carcinoma cells through inhibition of mevalonate pathway

AIM

Skeletal metastases and bone metasitasis are a common occurrence in patients with advanced hepatocellular carcinoma (HCC). Bisphosphonates (BPs), which are used for the treatment of osteoporosis and tumor-associated hypercalcemia, have recently been reported to decrease skeletal morbidity in patients with metastatic bone disease. Several studies revealed that nitrogen-containing BPs (N-BPs) could inhibit tumor growth and migration, indicating the possibility that N-BPs have direct inhibitory effects. We aimed to determine the effects of novel a N-BP (YM529) on human HCC cells in vitro.

METHODS

HCC cells were treated with various concentrations of YM529 and the growth inhibition rate was determined. Apoptosis was evaluated by caspase-3/7 assay and caspase-9 cleavage detection. The effects of YM529 on the migration of HCC cells induced by hepatocyte growth factor (HGF) were determined by cell migration assay. To evaluate the involvement of the mevalonate pathway, farnesol (FOH) and geranylgeraniol (GGOH) were added.

RESULTS

YM529 inhibited the proliferation of HCC cells in a dose-dependent manner. The activation of caspase-3/7 and cleavage of caspase-9 demonstrated the involvement of apoptosis in cytotoxicity. GGOH reduced the growth inhibitory effect of YM529 and suppressed the induction of caspase-3/7 activities by YM529 on HCC cells. YM529 inhibited tumor cell migration induced by HGF and this effect was reduced by co-treatment with GGOH.

CONCLUSION

YM529 inhibited the cell proliferation and migration of HCC cells, implicating the involvement of the mevalonate pathway. These results suggest that N-BPs are potential agents for the treatment of HCC skeletal metastases.

New trends in the treatment of bone metastasis

Bone metastasis is often the penultimate harbinger of death for many cancer patients. Bone metastases are often associated with fractures and severe pain resulting in decreased quality of life. Accordingly, effective therapies to inhibit the development or progression of bone metastases will have important clinical benefits. To achieve this goal understanding the mechanisms through which bone metastases develop and progress may provide targets to inhibit the metastases. In the past few years, there have been advances in both understanding the mechanisms through which bone metastases develop and how they impact bone remodeling. Additionally, gains in promising clinical strategies to target bone metastases have been developed. In this prospectus, we will discuss some of these advances.

New developments of aminobisphosphonates: the double face of Janus

BACKGROUND

Bisphosphonate (BP) therapy has become a standard of therapy for patients with malignant bone disease. In vivo preclinical and preliminary clinical data indicate that BPs may prevent cancer treatment-induced bone loss and the onset of malignant bone disease in patients with early-stage cancer.

DESIGN

This review will describe the preclinical evidences of action of BPs on osteoclasts and tumor cells. In addition, the effects of principal BPs on skeletal disease progression in patients with breast cancer, prostate cancer, non-small-cell lung cancer and other cancers will be reported. The preliminary clinical data from retrospective trials on the effect of zoledronic acid (ZA) on survival will be described and the ongoing adjuvant phase III trial will be analyzed.

CONCLUSIONS

This review will describe the preliminary clinical evidences from prospective studies on the effect of ZA treatment on the prevention of bone metastasis.

Hyperbaric oxygen in addition to antibiotic therapy is effective for bisphosphonate-induced osteonecrosis of the jaw in a patient with multiple myeloma

A 60-year-old man with multiple myeloma (MM) (IgG-kappa, stage IIIA) had been treated with minodronate at 6 mg orally as a phase 1 clinical trial for myeloma bone disease for 13 months (total dose, 4032 mg). Then he received incadronate at 10mg intravenously every 1 to 4 weeks (total dose, 350 mg). In July 2005, he complained of mild right mandibular pain, and bone scintigram showed a hot spot at the right side of the mandible. Panoramic radiograph showed osteonecrosis of the jaw (ONJ) and axial and 3-dimensional computed tomography confirmed ONJ. Oral examination showed massive gingival swelling of the right side of the mandible without exposed necrotic bone. He was given clarithromycin in addition to levofloxacin, followed by hyperbaric oxygen (HBO) therapy, which resulted in the complete disappearance of the pain. This is a first reported case of ONJ induced by incadronate. The present case suggests that early detection of ONJ by regular dental check-ups is important in the management of patients with MM who have received bisphosphonate therapy, and HBO in combination with antibiotic therapy is effective in the early stage of ONJ.

Synergistic antimyeloma effects of zoledronate and simvastatin

Despite advances in the treatment of multiple myeloma, it remains an incurable disease because of primary and secondary drug resistance. Mevalonate pathway inhibitors like bisphosphonates and statins have antimyeloma activity in vitro at very high concentrations, which may probably not be reached in vivo. NCI-H929, OPM-2, U266 and RPMI-8226 myeloma cell lines were treated in the presence or absence of bone marrow stromal cells with simvastatin or zoledronate in combination with classical antimyeloma drugs like melphalan or bortezomib. Zoledronate did not show substantial antimyeloma activity at low and intermediate concentrations, whereas simvastatin potently induced apoptosis in myeloma cells without signs of primary, cell-adhesion-mediated drug resistance. Furthermore, sequential blockage of the mevalonate pathway by zoledronate and simvastatin demonstrated synergistic induction of apoptosis and reversal of cell-adhesion-mediated drug resistance. Our data provide a rationale for combining zoledronate and simvastatin with classical antimyeloma drugs.

Anti-tumor effect of bisphosphonate (YM529) on non-small cell lung cancer cell lines

Background

YM529 is a newly developed nitrogen-containing bisphosphonate (BP) classified as a third-generation BP that shows a 100-fold greater potency against bone resorption than pamidronate, a second-generation BP. This agent is, therefore expected to be extremely useful clinically for the treatment of osteoporosis and hypercalcemia. Recently, YM529 as well as other third-generation BPs have also been shown to exert anti-tumor effects against various types of cancer cells both in vitro or/and in vivo. In this study, we investigate the anti-tumor effect of YM529 on non-small cell lung cancer (NSCLC).

Methods

Direct anti-tumor effect of YM529 against 8 NSCLC cell lines (adenocarcinoma: H23, H1299, NCI-H1819, NCI-H2009, H44, A549, adenosquamous cell carcinoma: NCI-H125, squamous cell carcinoma: NCI-H157) were measured by MTS assay and calculated inhibition concentration 50 % (IC₅₀) values. YM529 induced apoptosis of NCI-H1819 was examined by DNA fragmentation of 2 % agarose gel electrophoresis and flowcytometric analysis (sub-G₁ method). We examined where YM529 given effect to apoptosis of NSCLC cells in signaling pathway of the mevalonate pathway by western blotting analysis.

Results

We found that there was direct anti-tumor effect of YM529 on 8 NSCLC cell lines in a dose-dependent manner and their IC₅₀ values were 2.1 to 7.9 μM and YM529 induced apoptosis and G₁ arrest cell cycle with dose-dependent manner and YM529 caused down regulation of phospholyration of ERK1/2 in signaling pathways of NSCLC cell line (NCI-H1819).

Conclusion

Our study demonstrate that YM529 showed direct anti-tumor effect on NSCLC cell lines in vitro, which supports the possibility that third-generation BPs including YM529 can be one of therapeutic options for NSCLC.

Expression and role of MHC class I-related chain in myeloma cells

BACKGROUND

The molecular mechanism of natural killer (NK) cell cytotoxicity to myeloma cells remains unclear. We investigated whether MHC class I-related chain (MIC), a ligand of NKG2D that is an activating NK cell receptor, is involved in the cytotoxicity of NK cells toward myeloma cells, and examined the effects of various drugs on the cytotoxicity.

METHODS

Two human myeloma cell lines and fresh myeloma cells from 10 patients were used. MIC expression was examined by flow cytometry and reverse transcription (RT)-PCR. NK cell cytotoxicity was examined using a 51Cr-release assay. The effects of various drugs, including thalidomide, all-trans retinoic acid, dexamethasone, IFN-alpha and incadronate, on the MIC expression and NK cell cytotoxicity were examined.

RESULTS

MIC was highly expressed on the human myeloma cell lines U266 and RPMI-8226 and in myeloma cells of one of 10 patients examined. MIC expression on these cells was not changed by various drugs except IFN-alpha, by which MIC expression was down-regulated. Although MIC and HLA class I molecules were similarly expressed at high levels on both cell lines, U266 was sensitive to NK cells whereas RPMI-8226 was not. Furthermore, cytolysis by NK cells was not inhibited by the addition of anti-MIC Ab or decreased expression of MIC caused by IFN-alpha.

DISCUSSION

MIC plays a role in the cytolysis by NK cells in multiple myeloma.

Treatment for Myeloma Bone Disease: Table 1

Multiple myeloma (MM) is a B cell malignancy characterized by enhanced bone loss commonly associated with diffuse osteopenia, focal lytic lesions, pathologic fractures, hypercalcemia, and bony pain. Bone destruction in MM results from asynchronous bone turnover wherein increased osteoclastic bone resorption is not accompanied by a comparable increase in bone formation. Consequently, patients with MM frequently require radiation therapy, surgery, and analgesic medications. The recent development of minimally invasive surgical procedures such as kyphoplasty allows patients with myeloma with vertebral compression fractures to have immediate improvement in their quality of life with shorter hospital stays. Bisphosphonates are specific inhibitors of osteoclastic activity, and these agents have been evaluated in patients with MM with bone disease during the past 15 years. Monthly i.v. infusions of either pamidronate or zoledronic acid have reduced the skeletal complications among patients with MM and are now a mainstay of myeloma therapy. Orally administered bisphosphonates, in contrast, have shown little ability to slow the development of skeletal complications in these patients. Although preclinical studies suggest that nitrogen-containing bisphosphonates have potent antitumor effects, clinical trials will be necessary, probably at higher doses given more slowly, to establish their possible antitumor effects clinically. Moreover, recent advances in the use of bone-seeking radiopharmaceuticals make these attractive therapeutic candidates to combine with bisphosphonates or radiosensitizing drugs (e.g., bortezomib) to achieve a synergistic effect. As our understanding of the pathophysiology of myeloma bone disease continues to grow, new target therapies will continue to emerge, offering new and more advanced options for the management of myeloma bone disease.

Myeloma bone disease and treatment options

Multiple myeloma (MM) is a B-cell malignancy characterized by enhanced bone loss commonly associated with a diffuse osteopenia, focal lytic lesions, pathologic fractures, hypercalcemia, and bony pain. Bone destruction in MM results from asynchronous bone turnover wherein increased osteoclastic bone resorption is not accompanied by a comparable increase in bone formation. Recent characterization of osteoclast-activating factors (OAFs), receptor activator of nuclear factor-kappaB (RANK) ligand (RANKL)-osteoprotegerin-RANK system, and inhibitors of Wnt signaling have provided a better understanding of myeloma bone disease in molecular level. The development of minimally invasive surgical procedures such as kyphoplasty and vertebroplasty allows myeloma patients with vertebral compression fractures to have immediate improvement in quality of life and shorter hospital stays. Monthly intravenous infusion of either pamidronate or zoledronic acid have reduced the skeletal complications among MM patients and are now a mainstay of myeloma therapy. Orally administered bisphosphonates, in contrast, have shown little ability to slow the development of skeletal complications in these patients. Although pre-clinical studies suggest nitrogen-containing bisphosphonates have potent anti-tumor effects, clinical trials will be necessary, probably at higher doses given more slowly, to establish their possible anti-tumor effects clinically. As our understanding of the pathophysiology of myeloma bone disease continues to increase, new target therapies will continue to emerge offering new and more advanced options for the management of myeloma bone disease.

Effect of combination therapy with a novel bisphosphonate, minodronate (YM529), and docetaxel on a model of bone metastasis by human transitional cell carcinoma

PURPOSE

Transitional cell carcinoma (TCC) of the urinary tract is a chemosensitive tumor. Most deaths from TCC of the urinary tract are caused by metastasis, which is resistant to conventional chemotherapy. Frequent sites of metastases from TCC of the urinary tract are regional lymph nodes, liver, lung, and bone. Of these distant metastases, bone metastasis is consistently resistant to cisplatin-based conventional chemotherapy. Therefore, in this study, we investigated whether or not a newly developed minodronate, YM529, could prevent osteolytic bone metastasis of human TCC and also enhance the effect of docetaxel in a bone tumor model of athymic nude mice.

EXPERIMENTAL DESIGN

In the present study, we evaluated the effect of in vitro treatment with minodronate and/or docetaxel on the proliferation by cell count, the induction of apoptosis by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay, and the biological activity of osteoclast by pit formation assay in human bladder cancer cell line, UMUC-14, and mouse osteoclast cells. In vivo, we examined the effect of minodronate in a bone tumor model of athymic nude mice, in which the percutaneous intraosseal injection in the tibia of UMUC-14, leads to osteolytic bone tumor, as a bone metastasis model. To examine whether or not minodronate could inhibit tumorigenicity and enhance the effect of the chemotherapeutic agent, docetaxel, we gave minodronate i.p. and/or docetaxel i.p. to nude mice 3 days after an intraosseal tumor implantation. Moreover, proliferation and the induction of apoptosis of cancer cells and osteoclasts in bone tumors were determined by immunohistochemistry and the TUNEL assay.

RESULTS

In vitro: In vitro treatment with docetaxel inhibited proliferation and resorption pit-forming activity and induced apoptosis of mouse osteoclast cells and UMUC-14 cells. In vitro treatment with minodronate inhibited proliferation and activity and induced apoptosis of mouse osteoclast cells but not UMUC-14 cells. The treatment with minodronate enhanced the inhibition of proliferation and activity by docetaxel in osteoclasts. In vivo: In vivo combination therapy with docetaxel and minodronate significantly reduced the tumor incidence compared with the control (P < 0.05) and also growth of intraossal TCC in athymic nude mice compared with the control (P < 0.001), single therapy with docetaxel (P < 0.01), and minodronate (P < 0.05). Drug-induced body weight loss was not significantly different in any treatment group. Therapy with minodronate significantly enhanced inhibition of proliferation by docetaxel in osteoclasts of bone tumors compared with the control (P < 0.01), single therapy with docetaxel (P < 0.01), and minodronate (P < 0.05).

CONCLUSIONS

These studies indicate that combination therapy with minodronate and docetaxel may be beneficial in patients with bone metastasis of human TCC in the urinary tract.

Combination Therapy with Thalidomide, Incadronate, and Dexamethasone for Relapsed or Refractory Multiple Myeloma

The feasibility and efficacy of a combination of thalidomide, incadronate, and dexamethasone (TID) were studied in 12 patients with relapsed or refractory multiple myeloma. The protocol, consisting of 300 mg/day of thalidomide administered orally, intravenous incadronate (10 mg/day) administered weekly, and 12 mg/day dexamethasone for 4 days, was repeated every 3 weeks. Evaluations of efficacy and toxicity were carried out every 3 weeks and were continued for 3 cycles. Three patients were excluded during the study because of apnea, severe somnolence, and pancytopenia. Of 9 evaluated patients, the partial responses achieved in 3 patients and the minor responses achieved in 4 patients corresponded to a response rate of 78% according to the criteria of the European Group for Blood and Marrow Transplantation. In addition, painful osteolytic symptoms improved rapidly after 1 cycle of TID therapy in the 10 patients evaluated. These data suggest that TID is a feasible and promising therapeutic approach for refractory and relapsed multiple myeloma.

The anti-leukemic efficacy of the third generation bisphosphonate ONO5920/YM529

Ras proteins are frequently over-expressed in leukemia and contribute to leukemogenesis. We evaluated the anti-leukemic efficacy of a new third-generation bisphosphonate, ONO5920/YM529 (YM529). YM529 prevents the prenylation of Ras proteins and inhibited the growth of leukemic cells including a P-glycoprotein (P-gp) over-expressing cell line in a concentration- and time-dependent manner by inducing apoptosis in vitro. Moreover, YM529 synergistically augmented the anti-leukemic activities of paclitaxel and daunorubicin in vitro. Importantly, YM529 prolonged the survival of NOD/SCID mice engrafted with human primary leukemic cells. These findings indicate that the YM529 may become a novel molecular therapeutic class for treatment of leukemias.

Bisphosphonates: preclinical review

Bisphosphonates effectively inhibit osteoclast-mediated bone resorption and are integral in the treatment of benign and malignant bone diseases. The evolution of bisphosphonates over the past 30 years has led to the development of nitrogen-containing bisphosphonates (N-BPs), which have a mechanism of action different from that of the nonnitrogen-containing bisphosphonates. Studies conducted over the past decade have elucidated the mechanism of action and pharmacologic properties of the N-BPs. N-BPs exert their effects on osteoclasts and tumor cells by inhibiting a key enzyme in the mevalonate pathway, farnesyl diphosphate synthase, thus preventing protein prenylation and activation of intracellular signaling proteins such as Ras. Recent evidence suggests that N-BPs also induce production of a unique adenosine triphosphate analogue (Apppi) that can directly induce apoptosis. Our increased understanding of the pharmacologic effects of bisphosphonates is shedding light on the mechanisms by which they exert antitumor effects. As a result of their biochemical effects on protein prenylation, N-BPs induce caspase-dependent apoptosis, inhibit matrix metalloproteinase activity, and downregulate alpha(v)beta(3) and alpha(v)beta(5) integrins. In addition, zoledronic acid (Zometa; Novartis Pharmaceuticals Corp.; East Hanover, NJ and Basel, Switzerland) exerts synergistic antitumor activity when combined with other anticancer agents. Zoledronic acid also inhibits tumor cell adhesion to the extracellular matrix and invasion through Matrigel trade mark and has antiangiogenic activity. A growing body of evidence from animal models demonstrates that zoledronic acid and other bisphosphonates can reduce skeletal tumor burden and prevent metastasis to bone. Further studies are needed to fully elucidate these biochemical mechanisms and to determine if the antitumor potential of bisphosphonates translates to the clinical setting.

Alendronate regulates cell invasion and MMP-2 secretion in human osteosarcoma cell lines

BACKGROUND

Osteosarcoma is the most common malignant bone tumor of childhood. Significant proportions of these patients eventually develop pulmonary metastases and succumb to their disease even after conventional multi-agent chemotherapy and surgical excision. Matrix metalloproteinase (MMP)-2 induced degradation of blood vessel basement membranes is an important pre-requisite for tumor invasion and metastasis. Bisphosphonates (BPs) have been known to inhibit tumor growth and metastasis in some tumors such as breast cancer, renal cell carcinoma, and prostate cancer, and may do so through inhibition of MMP secretion. We, therefore, tested the effect of BPs on tumor cell invasion, MMP-2 secretion, and apoptosis of osteosarcoma cell lines.

PROCEDURE

Two osteosarcoma cell lines (SaOS-2, U(2)OS) were treated with alendronate (50, 100, and 150 microM) for 24 and 48 hr. Matrigel invasion assay was used to investigate the invasive potential of osteosarcoma cell lines before and after alendronate treatment. Real-time quantitative RT-PCR was used to determine the mRNA level of MMP-2 with and without alendronate treatment. Enzyme-linked immunosorbent assay (ELISA) was used to quantify the cytokine level of MMP-2 secreted in the condition medium. BP-induced cell apoptosis was evaluated by fluorescent flow cytometric analysis.

RESULTS AND CONCLUSIONS

The results showed that alendronate inhibited cell invasion of both osteosarcoma cell lines in a dose-dependent manner. Alendronate reduced the mRNA level and cellular level of MMP-2 in both cell lines in a time and dose-dependent manner. Alendronate also induced significant apoptosis in both cell lines. Our finding suggests that alendronate downregulates MMP-2 secretion and induces apoptosis in osteosarcoma cells, which may both contribute to the reduction of invasive potential of the tumor cells.

The anti-tumor potential of zoledronic acid

Bone is a favorable microenvironment for tumor cell colonization because of abundant growth factors released during active bone resorption. Bisphosphonates can dramatically affect the ability of tumor cells to grow in bone by inhibiting osteoclast-mediated bone resorption and by depriving tumors of growth-promoting signals. Moreover, bisphosphonates have direct anti-tumor effects in vitro via induction of apoptosis. Zoledronic acid is a nitrogen-containing bisphosphonate that has demonstrated potent anti-tumor activity in vitro and in vivo. In vitro studies have provided important clues as to the molecular mechanisms by which zoledronic acid induces apoptosis of human breast cancer cell lines. Studies in multiple myeloma and breast cancer models have shed further light on the possible mechanisms underlying the in vivo anti-tumor effects of zoledronic acid. These studies have led to the development of novel strategies to target specific molecular pathways involved in osteoclast maturation and activity, tumor cell metastasis, and tumor growth and survival. The clinical application of these strategies may ultimately prevent bone metastasis.

A new bisphosphonate, YM529 induces apoptosis in HL60 cells by decreasing phosphorylation of single survival signal ERK

It is believed that bisphosphonates (BPs) induce apoptosis in cells such as myeloma cells, as they inhibit prenylation of G-proteins. However, the details of the apoptosis-inducing mechanism remain obscure. In the present study, we attempted to clarify the mechanism by which YM529, a new bisphosphonate, induces apoptosis. YM529 induced cell deaths in HL60 cells in a concentration-dependent manner. At that time, we observed an increase in Caspase-3 activity and morphological fragmentation of the nuclei. We could confirm that these cell deaths were evidence of apoptosis. The apoptosis induced by YM529 was not inhibited by the addition of farnesyl pyrophosphate (FPP), but was by the addition of geranylgeranyl pyrophosphate (GGPP). When we examined the survival signals at the time of apoptotic induction, we also observed that the administration of YM529 caused a remarkable decrease in the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). However, other survival signals such as nuclear factor kappa B (NF-kappaB), protein kinase B (Akt), and p38 mitogen-activated protein kinase (p38) exhibited no change. In addition, no quantitative change was observed in Bcl-2, which is an anti-apoptosis protein. It was also observed that apoptosis was induced when U0126, an MEK inhibitor, was added to the cells to inhibit ERK. These results suggest that YM529, the new bisphosphonate, induced apoptosis when inhibit GGPP synthase and consequently decreased the levels of phosphorylated ERK, which is a survival signal; moreover, during this process, there is no influence on NF-kappaB, Akt, p38, and Bcl-2. The results of this study also suggest that YM529 can be used as an anticancer agent, in addition to its use as a therapeutic agent to treat osteoporosis.

Nitrogen-containing bisphosphonates induce S-phase cell cycle arrest and apoptosis of myeloma cells by activating MAPK pathway and inhibiting mevalonate pathway

Bisphosphonates have been used for the treatment of hypercalcemia associated with malignancies and osteoporosis. It was previously reported that the mevalonate pathway is involved in nitrogen-containing bisphosphonate-induced apoptosis in osteoclasts and myeloma cells. The aim of this study was to determine the effects of two bisphosphonates, incadronate, and newly developed bisphosphonate YM529 on human myeloma cells, U266, RPMI-8226, and HS-Sultan. Both incadronate and YM529 induced S-phase cell cycle arrest and apoptosis in these myeloma cells. Treatment of the myeloma cells with cell-permeable substrates for mevalonate pathways, geranylgeraniol, and farnesol prevented bisphosphonate-mediated growth suppression. Checkpoint kinases, Chk1/2, and MAPK became phosphorylated after stimulation with bisphosphonates in the myeloma cells. Bisphosphonate-induced apoptosis was partially prevented by the pretreatment with MAPK inhibitor. These results demonstrate that incadronate and YM529 suppress the proliferation of myeloma cells through mevalonate pathway and MAPK pathway.

How myeloma cells escape bisphosphonate-mediated killing: development of specific resistance with preserved sensitivity to conventional chemotherapeutics

Although amino-bisphosphonates (N-BPs) induce apoptosis of myeloma cells in vitro, most in-vivo studies fail to demonstrate a corresponding antitumour effect. This discrepancy might reflect the development of resistance to the antitumour effects of N-BP in myeloma cells when they are exposed to N-BP for a prolonged time. To test this hypothesis, two N-BP-sensitive human myeloma cell lines were continuously exposed to increasing concentrations of the N-BP alendronate for 6 weeks. During this treatment period, 10 out of 10 sublines developed reduced apoptotic and antiproliferative responses to alendronate treatment. This de novo alendronate resistance was accompanied by resistance to another N-BP (zoledronate) but not to an inhibitor of 3-hydroxy-3-methylglutaryl CoA reductase or Fas ligand. Importantly, N-BP-resistant myeloma cells also remained sensitive to conventional myeloma chemotherapeutics (melphalan, doxorubicin and vincristine). Further analysis of the N-BP-resistant cells revealed an increased activity of the N-BP-specific target enzyme farnesyl pyrophosphate synthase, without upregulation of its gene transcription. Our results suggest that continuous exposure of myeloma cells to alendronate leads to the development of N-BP resistance. This is associated with an increased activity of farnesyl pyrophosphate synthase and does not evolve from defective apoptotic pathways. Importantly, the antitumour effects of conventional myeloma chemotherapeutics are preserved in the N-BP-resistant myeloma cells.

A novel bisphosphonate minodronate (YM529) specifically inhibits osteolytic bone metastasis produced by human small-cell lung cancer cells in NK-cell depleted SCID mice

In the present study, we examined the effects of a newly developed bisphosphonate, minodronate (YM529), on osteolytic bone metastasis caused by lung cancer. Human small-cell lung cancer (SBC-5) cells, injected intravenously into natural killer cell-depleted SCID mice, produced radiologically detectable bone metastasis by day 18 and macroscopically visible visceral metastases (lung, liver, kidney, systemic lymph node) by day 35. Prophylactic treatment with YM529 on day 1 significantly inhibited the formation of osteolytic bone metastasis evaluated on X-ray photographs in a dose-dependent manner. In addition, treatment with YM529 after establishment of bone metastasis (on day 21) also inhibited bone metastasis, although the treatment was more effective when started earlier. Single administration was as effective as repeated treatment, suggesting a sustained inhibitory effect of YM529 on bone metastasis. YM529 reduced the number of osteoclasts in the bone metastatic lesions in vivo, but had no effect on the proliferation or cytokine production of SBC-5 cells in vitro. These results suggest that YM529 is a potent inhibitor of bone metastasis of human lung cancer, probably by suppressing osteoclastic bone resorption. In contrast, treatment with YM529 had no effect on visceral metastasis, even if started on day 1, and did not prolong the survival of the mice. Therefore, development of a combined modality is necessary for prolonging the survival of small-cell lung cancer patients with multiple-organ metastasis.

Humanized anti-interleukin-6 receptor monoclonal antibody induced apoptosis of fresh and cloned human myeloma cells in vitro

We investigated the effect of anti-IL-6 receptor monoclonal antibody (hPM1) on the in vitro proliferation of cloned and freshly isolated myeloma cells from 20 patients with advanced stage multiple myeloma (MM). Humanized PM1 significantly inhibited the growth of a myeloma cell line in a dose-dependent manner and inhibited more than 30% of the proliferation of fresh myeloma cells in 10 of the 19 cases. Flow cytometric analysis using annexin V and 7AAD showed that hPM1 induced apoptosis of myeloma cells. These observations suggest the possibility of using hPM1 for treating some patients with MM whose growth depends on IL-6.

Antitumor effects of bisphosphonates

BACKGROUND

Bisphosphonates are widely used to treat skeletal complications of malignancy. These drugs accumulate in bone where they inhibit osteoclastic bone resorption and reduce the local release of factors that stimulate tumor growth. The mechanism of action of bisphosphonates is dependent on chemical structure: Nonnitrogen-containing compounds (e.g., etidronate, clodronate) are metabolized into cytotoxic analogues of ATP, whereas the more potent nitrogen-containing compounds (N-BPs; e.g., pamidronate, ibandronate, zoledronic acid) inhibit protein prenylation, thus affecting cell function and survival. Because protein prenylation is required by all cells, not just osteoclasts, the possibility arises that N-BPs could also affect the viability of tumor cells.

METHODS

Several groups have investigated the in vitro effects of bisphosphonates, either alone or in combination with other antineoplastic agents, on the viability and metastatic properties of many tumor cell types. Similarly, the effect of bisphosphonate treatment on osteolysis and tumor burden has been studied in a variety of animal tumor models.

RESULTS

In vitro, submicromolar concentrations of N-BPs inhibited tumor cell adhesion and reduced invasion through extracellular matrix. At higher concentrations, antiproliferative and proapoptotic effects have been reported. In animal models of bone metastases, bisphosphonate treatment markedly reduced osteolytic lesions. There is also evidence of a reduction in tumor burden in bone and occasionally in other organs. Survival may be prolonged, but bisphosphonates do not appear to inhibit the growth of primary soft tissue tumors or orthotopic xenografts.

CONCLUSIONS

The cell culture data clearly demonstrated that N-BPs exert antitumor properties and interact synergistically with other antineoplastic agents. As bisphosphonates accumulate in bone, they can also exert cytostatic effects on tumor cells in bone metastases, either directly or indirectly via osteoclast inhibition and alterations in the bone microenvironment. Further in vivo research is now required to optimize the dosing regimen of N-BPs to exploit fully their antitumor potential.

Apoptosis-inducing effect of a new bisphosphonate, YM529, on various hematopoietic tumor cell lines

In recent years, it has been reported that bisphosphonates inhibited the cell cycle of myeloma cells to inhibit cell proliferation directly, and it was also reported that bisphosphonates induced apoptosis of myeloma cells in vitro. Recently, YM529 was developed as a new third-generation bisphosphonate. In our experiment, we investigated whether YM529 showed an antitumor effect on hematopoietic tumor cell lines other than myeloma, and we compared YM529 with YM175, which had a relatively more potent antitumor effect than that of existing bisphosphonates. We found that YM529 inhibited cell proliferation in various hematopoietic tumor cell lines (acute promyelocytic leukemia cell line HL-60, chronic myeloid leukemia cell line K562, histiocytic lymphoma cell line U937, lymphoblastic leukemia T cell line Jurkat, acute lymphoblastic leukemia T cell line MOLT-4, lymphoblastic leukemia B cell line CCRF-SB) including myeloma (myeloma cell line HS-Sultan) dose-dependently and time-dependently to a degree equivalent or superior to that in myeloma, and induced apoptosis at a lower concentration as compared with YM175. We confirmed many dead cells as well as apoptosis based on the detection of the nuclei with separate globular structure, the activation of caspase-3, and the decrease in mitochondrial transmembrane potential. Therefore, it is concluded that further utilization of YM529 can be expected against hematopoietic tumor cells in the future.

Future directions in the treatment and prevention of bone metastases

Preclinical studies are providing a growing body of evidence that bisphosphonates, particularly nitrogen-containing bisphosphonates, have antitumor activity. Bisphosphonates induce tumor cell apoptosis and reduce skeletal tumor burden in tumor xenograft models. Clinical studies with daily oral clodronate suggest that bisphosphonates can prevent bone metastases when used in the adjuvant setting, but the effect on overall survival is less certain. The more potent nitrogen-containing bisphosphonates, i.e., pamidronate and zoledronic acid, have demonstrated antitumor activity at approximately 10- to 100-fold lower concentrations than clodronate in vitro. A number of important unanswered questions must be addressed regarding the optimal use of bisphosphonates for prevention of bone metastases. For example, when should treatment begin, how long must treatment be continued, and what are the optimal dose and schedule to achieve clinically meaningful antitumor effects? Adjuvant studies of zoledronic acid in patients with breast and prostate cancer are under development, and the results are eagerly anticipated.

Mechanisms of bisphosphonate effects on osteoclasts, tumor cell growth, and metastasis

Bisphosphonates are potent inhibitors of osteoclast-mediated bone resorption that also exhibit antitumor activity. There is now extensive in vitro evidence that bisphosphonates inhibit proliferation and induce apoptosis of tumor cell lines. In addition, they appear to inhibit tumor cell adhesion and invasion of the extracellular matrix. These data are supported by a growing body of evidence from animal models demonstrating that bisphosphonates can reduce skeletal tumor burden. This may reflect direct antitumor effects or indirect effects via osteoclast inhibition and alteration of the bone microenvironment. Research has begun to shed light on the complex mechanisms by which bisphosphonates inhibit bone resorption and interfere with the formation and growth of bone lesions. Nitrogen-containing bisphosphonates inhibit protein prenylation and thereby short-circuit intracellular signaling via small guanine triphosphatases, such as Ras, which require membrane localization. As a result of these biochemical effects on the mevalonate pathway, bisphosphonates appear to modulate the expression of bcl-2 leading to caspase-dependent apoptosis, inhibit matrix metalloproteinases, downregulate alphavbeta3 and alphavbeta5 integrins, and increase expression of osteoprotegerin, thereby antagonizing osteoclastogenesis. Further preclinical studies are ongoing to fully elucidate these biochemical mechanisms, and well-designed clinical trials are necessary to investigate whether the antitumor potential of bisphosphonates can be realized in the clinical setting.

Bisphosphonates in cancer therapy

Bisphosphonates inhibit osteoclast-mediated bone resorption in metastatic bone disease. A wealth of preclinical data have begun to shed light on the complex mechanisms by which bisphosphonates inhibit bone resorption and interfere with the formation and growth of bone metastases. Nitrogen-containing bisphosphonates inhibit the mevalonate pathway, which results in the inhibition of osteoclast function and the induction of apoptosis in osteoclasts and tumor cells alike. There is now extensive evidence that bisphosphonates have cytostatic activity against tumor cell lines and inhibit tumor cell adhesion and invasion of the extracellular matrix. These data are supported by a growing body of evidence from animal models demonstrating that bisphosphonates can reduce skeletal tumor burden. However, it remains unclear whether this reduction reflects a direct antitumor effect or an indirect effect via osteoclast inhibition and alteration of the bone microenvironment. Further preclinical studies are needed to elucidate these biochemical mechanisms fully; ultimately, well-controlled clinical trials will be required to investigate whether the antitumor potential of bisphosphonates translates into a significant clinical benefit for patients with cancer.

Bisphosphonate therapy in multiple myeloma: past, present, future

Bone disease characterised by osteolytic lesions, pathological fractures and hypercalcaemia is an important clinical feature in multiple myeloma. Pain, decreased performance status, and the need for palliative radiotherapy and surgical interventions are common sequelae. Bisphosphonates act primarily on osteoclasts to inhibit excessive bone resorption, and have therefore been investigated in myeloma patients to ameliorate the clinical consequences of the bone disease. Bisphosphonates are currently the therapy of choice in myeloma patients with hypercalcaemia. In long-term management, both oral clodronate and intravenous pamidronate are effective in reducing skeletal-related events. Zoledronic acid seems to be as effective as pamidronate. Whether bisphosphonates have antimyeloma activity is currently unknown. Cost-benefit analyses have shown reasonable efficacy with acceptable costs. Bisphosphonate therapy is now accepted as an important part of care in myeloma patients, although much still has to be learned in order to optimise this therapy in multiple myeloma.

Pamidronate causes apoptosis of plasma cells in vivo in patients with multiple myeloma

Anti-resorptive bisphosphonates, such as pamidronate, are an effective treatment for osteolytic disease and hypercalcaemia in patients with multiple myeloma, but have also been shown to cause apoptosis of myeloma cell lines in vitro. In this study, we found that a single infusion of pamidronate, in 16 newly diagnosed patients with multiple myeloma, caused a marked increase in apoptosis of plasma cells in vivo in 10 patients and a minimal increase in four patients (P < 0.05). The nitrogen-containing bisphosphonates pamidronate and zoledronic acid also induced apoptosis of authentic, human bone marrow-derived plasma cells in vitro. Apoptosis of plasma cells in vitro was probably caused by inhibition of the mevalonate pathway and loss of prenylated small GTPases, as even low concentrations (>or= 1 micro mol/l) of zoledronic acid caused accumulation of unprenylated Rap1A in cultures of bone marrow mononuclear cells in vitro. GGTI-298, a specific inhibitor of geranylgeranyl transferase I, also induced apoptosis in human plasma cells in vitro, suggesting that geranylgeranylated proteins play a role in signalling pathways that prevent plasma cell death. Our results suggest that pamidronate may have direct and/or indirect anti-tumour effects in patients with multiple myeloma, which has important implications for the further development of the more potent nitrogen-containing bisphosphonates, such as zoledronic acid, in the treatment of myeloma.

Effect of vinorelbine on the growth of human myeloma cell lines in vitro

Vinorelbine (NVB) is a newly synthesized vinca alkaloid that has been used to treat advanced malignant diseases including lung adenocarcinoma and lymphoma. The effect of NVB on myeloma, however, is unknown. We therefore examined the effect of NVB on the growth of human myeloma cell lines (RPMI8226, U266 and KPMM2) using the trypan blue dye exclusion test and Alamar blue assay. NVB inhibited the growth of myeloma cells of all three cell lines dose-dependently and this effect was intensified when NVB was combined with dexamethasone at 1.0 x 10(-6)mol/l. Flow cytometric analysis using annexin V (AN) and 7-amino-actinomycin D (7AAD) showed that NVB-induced apoptosis of these myeloma cells in all the cell lines. NVB appears to be a potent inducer of apoptosis in myeloma cells, and might have some benefit in the treatment of myeloma patients.

Synergistic growth inhibition of YM529 with biologic response modifiers (BRMs) in myeloma cells

Bisphosphonates (BPs) are effective in the management of bone disease in patients with multiple myeloma. Recent reports have suggested that they may also have an antitumor activity. YM529 is a new synthetic BP with more than 1000 times the bone resorption inhibitory activity of pamidronate. To clarify the direct effects of YM529 on myeloma cells, the cell proliferation and cell cycle perturbation were analyzed using 12 myeloma cell lines established in our laboratory. The growth inhibition was dose dependent. The cells accumulated in [2n<<4n] of the cell cycle and subsequently formed an apoptotic sub-G1 fraction. Combined treatment with all-trans retinoic acid, thalidomide, or interferon-alpha enhanced the growth inhibitory effects of YM529 on these cells. However, there were no remarkable effects of YM529 on the messenger RNA expression for angiogenic factors, cell cycle regulators, or cytokines related to myeloma cells. These results indicate that YM529 is beneficial not only to bone lesions but also for its direct antitumor effects on myeloma cells.