Loading and skeletal development and maintenance

Mechanical loading is a major regulator of bone mass and geometry. The osteocytes network is considered the main sensor of loads, through the shear stress generated by strain induced fluid flow in the lacuno-canalicular system. Intracellular transduction implies several kinases and phosphorylation of the estrogen receptor. Several extra-cellular mediators, among which NO and prostaglandins are transducing the signal to the effector cells. Disuse results in osteocytes apoptosis and rapid imbalanced bone resorption, leading to severe osteoporosis. Exercising during growth increases peak bone mass, and could be beneficial with regards to osteoporosis later in life, but the gain could be lost if training is abandoned. Exercise programs in adults and seniors have barely significant effects on bone mass and geometry at least at short term. There are few data on a possible additive effect of exercise and drugs in osteoporosis treatment, but disuse could decrease drugs action. Exercise programs proposed for bone health are tedious and compliance is usually low. The most practical advice for patients is to walk a minimum of 30 to 60 minutes per day. Other exercises like swimming or cycling have less effect on bone, but could reduce fracture risk indirectly by maintaining muscle mass and force.

Renal tolerability of intermittent intravenous ibandronate treatment for patients with postmenopausal osteoporosis: a review

While intravenous (IV) bisphosphonates are well established in managing metastatic bone disease and hypercalcemia of malignancy, oral bisphosphonates are the primary treatment for postmenopausal osteoporosis. The availability of a well-tolerated, effective, IV bisphosphonate regimen for postmenopausal osteoporosis would increase physicians' options, allowing treatment of patients who cannot tolerate oral therapy, for whom oral bisphosphonates should be avoided or patients who are unable to comply with the oral dosing recommendations. Ibandronate is a potent, nitrogen-containing bisphosphonate, with proven efficacy and good tolerability when administered intermittently either orally or intravenously. Preclinical experience in animal models with IV ibandronate indicated that it had good renal tolerability. These data are supported by clinical pharmacology studies. Prolonged follow-up of patients receiving intermittent IV 15-30 second injections of 0.5-3 mg IV ibandronate has demonstrated no clinical evidence of renal toxicity in patients with postmenopausal osteoporosis. What is seen in controlled studies is not always the case in uncontrolled studies, however, no reports of renal failure have been received in post-marketing surveillance of >500,000 patients receiving IV ibandronate infusions in various indications including metastatic breast and prostate cancer. The good renal tolerability of IV ibandronate in patients with osteoporosis with glomerular filtration rates >30 mL/minute and without renal co-morbid conditions is reassuring.

[Absolute risk fracture prediction by risk factors validation and survey of osteoporosis in a Brussels cohort followed during 10 years (FRISBEE study)]

Osteoporosis is a major public health problem. For the time being, the diagnosis of osteoporosis relies on densitometry (T-score < -2.5 by DXA), although the risk of fracture depends also on other factors than the bone mass. Osteoporosis diagnosis (DXA) must be distinguished from the individual risk assessment of fracture. Different risk factors complementary to bone mass have been already validated in different populations. These include an old age, a history of fracture after the age of 50, a familial history of hip fracture (father or mother), a low BMI (< 20), corticoid treatment (> 3 months), tabagism and excessive alcohol consumption. A WHO taskforce has combined these different factors in order to integrate them in a 10-years predictive risk model of fracture (FRAX**). This model should still be validated in different populations, especially in populations not included in its development, which is the case for Belgium. We are evaluating these different risk factors for fracture in a Brussels population of 5000 women (60-80 years) who will be followed each year during 10 years. We also assess the predictive value of other risk factors for fracture not included in the WHO model (tendency to fall, use of sleeping pills, early non substituted menopause, sedentarity, ...). In an interim analysis of the first 452 women included and with data yet available at the time of this writing, we could find a significant (P < 0.05) relationship between diagnosis of osteoporosis at DXA and the number of risk factors, age > 70 years, a personal history of fracture after 50 years and a BMI < 20.

[Update on treatment of postmenopausal osteoporosis]

The most frequent sites of osteoporotic fractures are the vertebrae, the hip, the forearm and the proximal humerus. Drugs that inhibit bone resorption constitute the mainstay for the treatment of postmenopausal osteoporosis. A recent meta-analysis indicates that vitamin D can reduce the risk of hip fractures only if calcium supplements are also administered. The effect of hormone replacement therapy on the risk of non vertebral fractures is less clear than on vertebral fractures. Raloxifene (a SERM) reduces the rate of vertebral fractures and of breast cancer, but it does not protect against hip fracture. Bisphosphonates are the most commonly used compounds to treat postmenopausal osteoporosis. The level of evidence for currently used bisphosphonates (alendronate, ibandronate, risedronate, zoledronate) to reduce vertebral fracture rate is maximal. Results of controlled clinical trials indicate a reduction in the risk of vertebral fractures of 40-50% and of 20-40% for non vertebral fractures, including hip fractures. However, their relative efficacy on hip fractures has been less well studied and remains more controversial. Long-term compliance of bisphosphonate therapy is improved by intermittent schemes. The most recent developpements concern the intravenous administration of ibandronate and even more of zoledronate (yearly infusions). The reduction in the rate of vertebral and hip fractures has been demonstrated in the main zoledronate trial and a prolongation of survival has been shown in the study including patients with a recent hip fracture. Whereas hyperparathyroidism is a cause of bone loss, the intermittent administration of parathyroid hormone or of its 1-34 fragment (teriparatide) exerts anabolic effects on the skeleton. The treatment is demanding and costly (daily sc injections during 18 months), requires some monitoring (serum and urinary calcium) but the results, at least for vertebral fractures, are quite favorable. Strontium ranelate is a less powerful stimulator of bone formation but it also reduces bone resorption. Its daily administration for 3 years reduces the risk of vertebral fractures and, to a lesser extent, of non vertebral fractures. Lastly, denosumab is a high affinity antibody against RANK Ligand that specifically blocks the formation and the activity of osteoclasts. The efficacy of this promising compound will soon be known.

Guidance on the use of bisphosphonates in solid tumours: recommendations of an international expert panel

Bisphosphonates (BP) prevent, reduce, and delay cancer-related skeletal complications in patients, and have substantially decreased the prevalence of such events since their introduction. Today, a broad range of BP with differences in potency, efficacy, dosing, and administration as well as approved indications is available. In addition, results of clinical trials investigating the efficacy of BP in cancer treatment-induced bone loss (CTIBL) have been recently published. The purpose of this paper is to review the current evidence on the use of BP in solid tumours and provide clinical recommendations. An interdisciplinary expert panel of clinical oncologists and of specialists in metabolic bone diseases assessed the widespread evidence and information on the efficacy of BP in the metastatic and nonmetastatic setting, as well as ongoing research on the adjuvant use of BP. Based on available evidence, the panel recommends amino-bisphosphonates for patients with metastatic bone disease from breast cancer and zoledronic acid for patients with other solid tumours as primary disease. Dosing of BP should follow approved indications with adjustments if necessary. While i.v. administration is most often preferable, oral administration (clodronate, IBA) may be considered for breast cancer patients who cannot or do not need to attend regular hospital care. Early-stage cancer patients at risk of developing CTIBL should be considered for preventative BP treatment. The strongest evidence in this setting is now available for ZOL. Overall, BP are well-tolerated, and most common adverse events are influenza-like syndrome, arthralgia, and when used orally, gastrointestinal symptoms. The dose of BP may need to be adapted to renal function and initial creatinine clearance calculation is mandatory according to the panel for use of any BP. Subsequent monitoring is recommended for ZOL and PAM, as described by the regulatory authority guidelines. Patients scheduled to receive BP (mainly every 3-4 weeks i.v.) should have a dental examination and be advised on appropriate measures for reducing the risk of jaw osteonecrosis. BP are well established as supportive therapy to reduce the frequency and severity of skeletal complications in patients with bone metastases from different cancers.

The use of bone markers in a 6-week study to assess the efficacy of oral clodronate in patients with metastatic bone disease

Biochemical markers of bone metabolism are strongly associated with skeletal complications in metastatic bone disease. The bisphosphonate clodronate reduces skeletal morbidity by inhibiting bone resorption. This study investigated the use of bone markers to assess the efficacy of oral clodronate across a range of clinically relevant doses. There were 125 patients with metastatic bone disease randomized to daily oral clodronate (800, 1,600, 2,400 and 3,200 mg) or placebo in a double-blind, multicenter study. Urinary N-terminal telopeptide of type I collagen (U-NTX), serum C-terminal telopeptide of type I collagen (S-CTX), urinary calcium (U-Ca), and bone alkaline phosphatase were measured weekly for a 6-week treatment period. Doses of >or=1,600 mg clodronate produced mean reductions of >40% in U-NTX, S-CTX and U-Ca, all significantly different from placebo (P=0.0015, 0.001, 0.0036, respectively), after 6 weeks. Evaluation of least significant changes in markers suggested that the commonly used 1,600 mg dose was most appropriate for breast cancer patients. However, this dose was suboptimal for other (mainly prostate cancer) patients, who showed better response to 2,400 mg. The number of adverse events in the treatment arms was not significantly different from that in placebo, but a higher number of patients had diarrhea in the 3,200 mg arm and withdrew from the study. This trial is the first to explore the dose-response relationship of clodronate in oncology using specific markers of bone turnover. It has confirmed that the 1,600 mg dose is safe and effective for breast cancer patients but may be suboptimal for the other tumors studied.

Management of cancer treatment-induced bone loss in early breast and prostate cancer -- a consensus paper of the Belgian Bone Club

Cancer treatment-induced bone loss (CTIBL) is one of the most important side effects of adjuvant antineoplastic treatment in hormone-dependent neoplasms. Chemotherapy, GnRH analogs and tamoxifen can induce marked bone loss in premenopausal women with early breast cancer. Aromatase inhibitors (AIs) are replacing tamoxifen as the preferred treatment for postmenopausal women. As a class effect, steroidal (exemestane) and non-steroidal (anastrozole and letrozole) AIs increase bone turnover and cause bone loss (4%-5% over 2 years). When compared to tamoxifen, the risk of getting a clinical fracture under AI treatment is increased by 35%-50%. In patients with prostate cancer, androgen deprivation therapy (ADT) increases bone turnover, reduces bone mass (4%-5% per year) and increases the fracture rate depending on the duration of therapy. Zoledronic acid can prevent accelerated bone loss induced by goserelin in premenopausal women, by letrozole in postmenopausal women and by ADT in men. More limited data indicate that weekly alendronate or risedronate could also be effective for preventing CTIBL. Initiation of therapy early, prior to the occurrence of severe osteoporosis, rather than after, may be more effective. Bisphosphonate treatment should be considered in osteoporotic but also in osteopenic patients if other risk factor(s) for fractures are present.

Increased Dickkopf-1 expression in breast cancer bone metastases

The aim of this study was to determine whether Dickkopf-1 (Dkk-1) expression in breast cancer was associated with bone metastases. We first analysed Dkk-1 expression by human breast cancer cell lines that induce osteolytic or osteoblastic lesions in animals. Dickkopf-1 levels were then measured in the bone marrow aspirates of hind limbs from eight NMRI mice inoculated with breast cancer cells that induced bone metastases and 11 age-matched non-inoculated control animals. Finally, Dkk-1 was measured in the serum of 17 women with breast cancer in complete remission, 19 women with breast cancer and bone metastases, 16 women with breast cancer and metastases at non-bone sites and 16 healthy women. Only breast cancer cells that induce osteolytic lesions in animals produced Dkk-1. There was a six-fold increase in Dkk-1 levels in the bone marrow from animals inoculated with MDA-B02 cells when compared with that of control non-inoculated animals (P=0.003). Median Dkk-1 levels in the serum of patients with breast cancer and bone metastases were significantly higher than levels of patients in complete remission (P=0.016), patients with breast cancer having metastases at non-bone sites (P<0.0001) and healthy women (P=0.047), although there was a large overlap in individual levels between the different groups. In conclusion, Dkk-1 is secreted by osteolytic human breast cancer cells lines and increased circulating levels are associated with the presence of bone metastases in patients with breast cancer. Measurements of circulating Dkk-1 levels may be useful for the clinical investigation of patients with breast cancer and bone metastases.

Zoledronic acid efficacy and safety over five years in postmenopausal osteoporosis

In a 5-year study involving 119 postmenopausal women, zoledronic acid 4 mg given once-yearly for 2, 3 or 5 years was well tolerated with no evidence of excessive bone turnover reduction or any safety signals. BMD increased significantly. Bone turnover markers decreased from baseline and were maintained within premenopausal reference ranges.

INTRODUCTION

After completion of the core study, two consecutive, 2-year, open-label extensions investigated the efficacy and safety of zoledronic acid 4 mg over 5 years in postmenopausal osteoporosis.

METHODS

In the core study, patients received 1 to 4 mg zoledronic acid or placebo. In the first extension, most patients received 4 mg per year and then patients entered the second extension and received 4 mg per year or calcium only. Patients were divided into three subgroups according to years of active treatment received (2, 3 or 5 years). Changes in BMD and bone turnover markers (bone ALP and CTX-I) were assessed.

RESULTS

All subgroups showed substantial increases in BMD and decreases in bone markers. By the end of the core study, 37.5% of patients revealed a suboptimal reduction (< 30%) of bone ALP levels. After subsequent study drug administration during the extensions, there was no evidence of progressive reduction of bone turnover markers. Furthermore, increased marker levels after treatment discontinuation demonstrates preservation of bone remodelling capacity.

CONCLUSIONS

This study showed that zoledronic acid 4 mg once-yearly was well tolerated and effective in reducing biomarkers over 5 years. Detailed analysis of bone marker changes, however, suggests that this drug regimen causes insufficient reduction of remodelling activity in one third of patients.

Intravenous ibandronate does not affect time to renal function deterioration in patients with skeletal metastases from breast cancer: phase III trial results

As patients with metastatic bone disease typically receive long-term treatment with bisphosphonates, and often antineoplastic compounds, drug-related safety is of considerable importance. Clinical trial data for intravenous (i.v.) ibandronate suggest that its nephrotoxic potential is comparable with placebo. We conducted a post hoc Kaplan-Meier analysis of time to serum creatinine increase with i.v. ibandronate throughout 2 years of treatment. After 96 weeks, 12% of patients in the placebo group and 6% in the ibandronate 6 mg group (ns, P = 0.22) had defined serum creatinine increases. After 12 treatment months (48 weeks), 4% of patients receiving placebo and 2% of patients receiving ibandronate 6 mg showed increased serum creatinine. These results suggest that there is no clinically relevant change in serum creatinine levels with i.v. ibandronate 6 mg infused every 3-4 weeks for 2 years. Comparative trials to examine the renal safety of ibandronate and other i.v. bisphosphonates are warranted.

[Treatment of Paget's disease of bone with zoledronic acid]

Bone pain and bone deformities are the most common manifestations of Paget's disease of bone, even if the diagnosis is nowadays most often made by chance following a routine measurement of serum alkaline phosphatase. Woven bone is formed following a marked increase in bone resorption due to a stimulation of osteoclast activity. Biphosphonates constitute the modern treatment of Paget's disease of bone. Tiludronate (Skelid), or better risedronate (Actonel), are administered orally every day during at least 2 months. Zoledronic acid (Aclasta), as a single 15-min 5 mg infusion, has been recently compared to risedronate, 30 mg/d orally for 2 months, in two randomized studies including 357 patients. Zoledronic acid had a superior therapeutic efficacy, as judged by its rapidity of action, the duration of the biochemical response and the percentage of responders. Thus, at 6 months, alkaline phosphatase levels were normalized in 89% of the patients in the zoledronic acid group as compared to 58% in the risedronate group. The most frequent side effect was a flu-like syndrome, observed in 10% of the patients. An adequate intake of calcium and vitamin D is recommended to avoid posttreatment hypocalcemia. The introduction of Aclasta should simplify and improve the therapeutic management of Paget's disease of bone.

Cost-effectiveness of oral ibandronate versus IV zoledronic acid or IV pamidronate for bone metastases in patients receiving oral hormonal therapy for breast cancer in the United Kingdom

BACKGROUND

Oral ibandronate is a single-nitrogen bisphosphonate whose efficacy is similar to that of IV ibandronate for the treatment of bone metastases.

OBJECTIVE

The aim of this study was to compare the cost-effectiveness of oral ibandronate with zoledronic acid and generic pamidronate (both administered by IV) for the treatment of bone metastases in patients with breast cancer receiving oral hormonal therapy in the United Kingdom.

METHODS

A global economic model was adapted to the UK National Health Service. Patients were assumed to receive oral hormonal therapy for 50% of their projected 14.3-month survival. The primary outcome was incremental cost per quality-adjusted life-year (QALY). Bisphosphonate efficacy data for relative risk reduction of skeletal-related events (SREs) were obtained from clinical trials. Resource use data and costs associated with IV bisphosphonate infusions were derived from published studies and a unit cost database; monthly drug acquisition costs were obtained from the British National Formulary. Utility scores were applied to time with or without an SRE to adjust survival for quality of life. Therefore, differences in QALYs were driven by utility weights rather than survival time. Model design and inputs were validated through expert UK clinician review. The absence of comparative efficacy and safety data from clinical trials for the different bisphosphonates was a model limitation that we addressed by supporting our assumptions with UK expert clinician opinion and with expert clinician opinion outside of the United Kingdom, and by conducting sensitivity analyses.

RESULTS

The projected total cost per patient was pound307 less with oral ibandronate compared with zoledronic acid, and pound158 less compared with the use of generic pamidronate (due to a reduction in staff time for infusions, avoidance of renal safety monitoring visits, and, in the case of IV generic pamidronate, a reduction in the number of SREs). Oral ibandronate was estimated to lead to a gain of 0.02 QALY, making it the economically dominant treatment option.

CONCLUSIONS

In this study, we found that oral ibandronate was cost-effective for the management of bone metastases from breast cancer among patients receiving oral hormonal therapy in the United Kingdom. Oral ibandronate provided effective SRE and bone-pain management while avoiding resource use and costs associated with regular IV bisphosphonate infusions. Due to uncertainty surrounding the model assumptions, it would be valuable to repeat the analyses using data from comparative bisphosphonate trials, once they become available.

Cost-effectiveness of oral ibandronate compared with intravenous (i.v.) zoledronic acid or i.v. generic pamidronate in breast cancer patients with metastatic bone disease undergoing i.v. chemotherapy

BACKGROUND

Ibandronate is the first third-generation bisphosphonate to have both oral and intravenous (i.v.) efficacy. An incremental cost-effectiveness model compared oral ibandronate with i.v. zoledronic acid and i.v. generic pamidronate in female breast cancer patients with metastatic bone disease, undergoing i.v. chemotherapy.

METHODS

A global economic model was adapted to the UK National Health Service (NHS), with primary outcomes of direct healthcare costs and quality-adjusted life years (QALYs). Efficacy, measured as relative risk reduction of skeletal-related events (SREs), was obtained from clinical trials. Resource use data for i.v. bisphosphonates and the cost of managing SREs were obtained from published studies. Hospital management and SRE treatment costs were taken from unit cost databases. Monthly drug acquisition costs were obtained from the British National Formulary. Utility scores were applied to time with/without an SRE to adjust survival for quality of life. Model design and inputs were validated through expert UK clinician review.

RESULTS

Total cost, including drug acquisition, was pound 386 less per patient with oral ibandronate vs. i.v. zoledronic acid and pound 224 less vs. i.v. generic pamidronate. Oral ibandronate gained 0.019 and 0.02 QALYs vs. i.v. zoledronic acid and i.v. pamidronate, respectively, making it the economically dominant option. At a threshold of pound 30,000 per QALY, oral ibandronate was cost-effective vs. zoledronic acid in 85% of simulations and vs. pamidronate in 79%.

CONCLUSIONS

Oral ibandronate is a cost-effective treatment for metastatic bone disease from breast cancer due to reduced SREs, bone pain, and cost savings from avoidance of resource use commonly associated with bisphosphonate infusions.

[Gabapentin (Neurontin) and cancer pain: a pilot study]

Gabapentin (GBP) is a new antiepileptic agent with an original spectrum of activity. Its mechanism of action has not yet been fully elucidated but appears not to involve binding to GABA receptors despite being a structural analogue of GABA and is distinct from tricyclic antidepressants (TCAs). It has been shown to modulate high threshold calcium currents in brain neurons. As some other anticonvulsants, GBP has been recently proposed for the treatment of noncancer neuropathic pain like diabetic neuropathy and post herpetic neuralgia (double blind studies with placebo). We prospectively followed 20 cancer patients with advanced disease suffering from neuropathic pain. All were already treated for their pain syndrome. We started with 300 mg of GBP given orally in order to reach a dose of 900 mg on D3. All coanalgesics were stopped before entering the study. The only relevant side effect due to GBP was somnolence, otherwise time limited. GBP treatment was associated with a decrease of opioids doses in 9 patients and a decrease of VAS for pain intensity in all cases. Furthermore, the need of rescue doses decreased in all cases but 2. GBP appears to be one of the most effective drugs for the treatment of neuropathic pain. It is well tolerated and its effectiveness appears shortly after its administration. A synergistic action with opioids is suggested. Despite the small number of patients, our study suggests that GBP could be a treatment of neuropathic pain in cancer. Comparative trials should be performed with other neuropathic pain drugs including TCAs and antiepileptic drugs, especially carbamazepine.

Hypovitaminosis D in a normal, apparently healthy urban European population

Serum 25 OH Vitamin D (25 OH D) concentrations generally vary with latitude, season, and the composition of the population studied. There is a growing recognition that rather than a seasonal specific decline in serum 25 OH Vitamin D, a significant proportion of the population may exhibit asymtomatic subclinical Vitamin D insufficiency. Vitamin D insufficiency has been described in populations at risk, such as nursing home residents and the homebound elderly. We assessed a population of normal, apparently healthy volunteers at a single European urban center for 25 OH Vitamin D sufficiency. Serum 25 OH D concentrations were determined using an automated LIAISON((R)) 25 OH Vitamin D assay. For the purposes of this study, Vitamin D insufficiency was defined as a serum 25 OH Vitamin D concentration of <15 ng/mL. Of the total population (n = 126) 34% exhibited 25 OH Vitamin D concentrations of <15 ng/ml. The mean +/- S.D. serum 25 OH Vitamin D concentration among the total, sufficient, and insufficient populations was 19.4 +/- 7.7, 23.6 +/- 6.4, and 12.1 +/- 2.3 ng/mL. From these data, we conclude that 25 OH Vitamin D insufficiency is more common than previously thought, and is not restricted to high-risk groups.

Oral ibandronate reduces the risk of skeletal complications in breast cancer patients with metastatic bone disease: results from two randomised, placebo-controlled phase III studies

Although intravenous (i.v.) bisphosphonates are the standard of care for metastatic bone disease, they are less than ideal for many patients due to infusion-related adverse events (AEs), an increased risk of renal toxicity and the inconvenience of regular hospital visits. The use of oral bisphosphonate therapy is limited by concerns over efficacy and gastrointestinal (GI) side effects. There remains a clinical need for an oral bisphosphonate that offers equivalent efficacy to i.v. bisphosphonates, good tolerability and dosing convenience. Oral ibandronate, a highly potent, third-generation aminobisphosphonate, has been evaluated in phase III clinical trials of patients with bone metastases from breast cancer. In two pooled phase III studies, patients with breast cancer and bone metastases were randomised to receive oral ibandronate 50 mg (n=287) or placebo (n=277) once daily for up to 96 weeks. The primary end point was the skeletal morbidity period rate (SMPR), defined as the number of 12-week periods with new skeletal complications. Multivariate Poisson's regression analysis was used to assess the relative risk of skeletal-related events in each treatment group during the study period. Oral ibandronate 50 mg significantly reduced the mean SMPR compared with placebo (0.95 vs 1.18, P=0.004). There was a significant reduction in the mean number of events requiring radiotherapy (0.73 vs 0.98, P<0.001) and events requiring surgery (0.47 vs 0.53, P=0.037). Poisson's regression analysis confirmed that oral ibandronate significantly reduced the risk of a skeletal event compared with placebo (hazard ratio 0.62, 95% CI=0.48, 0.79; P=0.0001). The incidence of mild treatment-related upper GI AEs was slightly higher in the oral ibandronate 50 mg group compared with placebo, but very few serious drug-related AEs were reported. Oral ibandronate 50 mg is an effective, well-tolerated and convenient treatment for the prevention of skeletal complications of metastatic bone disease.

Management of primary osteoporosis

Although there is a great need for better therapeutic approaches to the patient who presents with a fracture, osteoporotic fractures will remain a condition that is more amenable to prevention than treatment. Hormone replacement therapy (HRT) is still considered by many the mainstay for the prevention and the treatment of posrmenopausal osteoporosis. However, there are several controversies regarding HRT, especially the duration of treatment and the risks/benefits ratio. Recent studies have challenged the assumption that HRT conveys real long-term beneficial effects. Raloxifene or other "selective estrogen receptor modulators" (SERMs) should progressively replace HRT in elderly women. Bisphosphonates have demonstrated a clearcut efficacy in the treatment of osteoporosis. Alendronate and risedronate have been the most extensively studied bisphosphonates under randomized controlled trials conditions. Both agents can reduce the risk of vertebral and hip fractures by one-fourth to one-half. However, oral bisphosphonates are not without gastro-intestinal toxicity and strict adherence to constraining therapeutic schemes is mandatory. Intermittent treatments are already in use. Weekly alendronate is as efficient as daily therapy and improves treatment compliance. Newer more potent bisphosphonates, such as oral ibandronate or intravenous zoledronic acid, will allow much less frequent administration. The anti-fracture efficacy of yearly zoledronic acid infusions is thus currently tested. On the other hand, bone-forming agents, such as daily subcutaneous injections of teriparatide (rhPTH 1-34) offer exciting perspectives for the treatment of severe osteoporosis despite the complexity of such therapy.

Bisphosphonates for cancer patients: why, how, and when?

Bisphosphonates (BPs) are potent inhibitors of osteoclast-mediated bone resorption, and it is well accepted that tumor cells in bone, especially breast cancer and myeloma cells, can stimulate osteoclast formation and activity leading to the release of growth factors or cytokines, which will further stimulate cancer cells' growth and their secretion of osteolytic factors. BPs are now the standard treatment for cancer hypercalcemia, for which a dose of 90 mg of pamidronate or 1500 mg of clodronate is recommended; the former compound is more potent and has a longer lasting effect. Repeated pamidronate infusions exert clinically relevant analgesic effects in more than half of patients with metastatic bone pain. Recent data suggest that non-responding patients should perhaps be treated with higher doses. The optimal dose actually remains to be defined, especially as it is thought that it is probably a function of the disease stage. Regular pamidronate infusions can also achieve a partial objective response according to conventional UICC criteria and they can almost double the objective response rate to chemotherapy. Lifelong administration of oral clodronate to patients with breast cancer metastatic to bone reduces the frequency of morbid skeletal events by more than one-fourth. Two double-blind randomized placebo-controlled trials comparing monthly 90 mg pamidronate infusions to placebo infusions for 1-2 years in addition to hormone or chemotherapy in patients with at least one lytic bone metastasis have shown that the mean skeletal morbidity rate could be reduced by 30-40%. The results obtained with intravenous BPs are generally viewed as better than those obtained with oral clodronate. However, preference can be given to the oral route when BPs are started early in the process of metastatic bone disease in a patient receiving hormone therapy. According to the recently published ASCO guidelines, pamidronate 90 mg i.v. delivered over 2 h every 3-4 weeks can be recommended in patients with metastatic breast cancer who have imaging evidence of lytic destruction of bone and who are concurrently receiving systemic therapy with hormonal therapy or chemotherapy. Furthermore, the ASCO Panel considered it "reasonable" to start i.v. BPs in women with localized pain whose bone scans were abnormal and plain radiographs normal, but not when an abnormal bone scan is asymptomatic. The pertinence of these criteria is discussed below. Because BPs are providing supportive care, reducing the rate of skeletal morbidity but evidently not abolishing it, the criteria for stopping their administration have to be different from those used for classic antineoplastic drugs, and they should not be stopped when metastatic bone disease is progressing. However, criteria to determine whether and for how long an individual patient benefits from their administration are lacking. New biochemical markers of bone resorption might help identify those patients continuing to benefit from therapy. Even better results have been achieved in patients with multiple myeloma, and the general consensus is that BPs should be started as soon as the diagnosis of lytic disease is made in myeloma patients. On the other hand, data are scanty in prostate cancer, but large-scale trials with potent BPs are ongoing or planned in such patients. Similar results to those achieved with pamidronate have been obtained with monthly 6-mg infusions of the newer BP ibandronate in patients with breast cancer metastatic to bone. The tolerance of ibandronate could be better, and the drug has the potential to be administered as a 15- to 30-min infusion. Zoledronate can also be administered safely as a 15-min 4-mg infusion, and large scale phase III trials have just been completed. These newer BPs will simplify the current therapeutic schemes and improve the cost-effectiveness ratio; they also have the potential to improve the therapeutic efficacy, at least in patients with an aggressive osteolytic disease or when given as adjuvant therapy. For that matter, initial data with clodronate indicate that they have the potential to prevent the development of bone metastases, but the use of BPs in the adjuvant setting must still be viewed as experimental.

Bisphosphonates influence the proliferation and the maturation of normal human osteoblasts

The key pharmacological action for the clinical use of bisphosphonates lies in the inhibition of osteoclast-mediated bone resorption. Osteoblasts could be other target cells for bisphosphonates. We studied the effects of bisphosphonates on the proliferation and the differentiation of normal human bone trabecular osteoblastic cells (hOB). We tested 4 different compounds: clodronate, pamidronate and 2 newer compounds: ibandronate, a nitrogen-containing bisphosphonate and zoledronate, which is a heterocyclic imidazole compound. Ibandronate and zoledronate stimulated hOB cell proliferation by up to 30% (p<0.05) after 72 h for concentrations ranging from 10(-8) M to 10(-5) M. Clodronate transiently enhanced hOB cell survival after only 24 h (+60%, p<0.001) whereas pamidronate had no effect. Longer time course studies, in presence of fetal calf serum, revealed that cell growth was finally reduced by all 4 bisphosphonates (40% after 7 days). Type I collagen synthesis was transiently increased by all 4 bisphosphonates after only 48 h incubation (+17% to +67%, p<0.05). Clodronate increased ALP activity by up to 1.7-fold after 4 days of culture (p<0.05) whereas ibandronate or zoledronate exhibited lesser stimulatory effects (+17 to +30%), and pamidronate had no significant effect. In conclusion, we found that different bisphosphonates, currently used or tested in various clinical conditions, transiently stimulated the growth of preosteoblastic cells and thereafter increased their differentiation according to sequential events (type I collagen synthesis first, then ALP activity to a lesser extent). Our data suggest that the beneficial effects of bisphosphonate treatment on bone mass and integrity could be partly mediated through a direct action on osteoblasts.

Supportive and palliative care: experience at the Institut Jules Bordet

The Supportive and Palliative Care Unit of the Institut Jules Bordet officially started its activities in February 1999. Our Unit comprises eight beds (four rooms with one bed each and two rooms with two beds each). We admit advanced cancer patients presenting with severe symptoms whose control is going to require all the expertise of a multidisciplinary team. Whilst these eight beds are identified geographically in the hospital, the team's mobility assures continuity of care for patients who wish to stay in another department. The infrastructure of the Unit and its rooms allow close family members who wish to sleep close to the patients to do so. Otherwise, visits are allowed round the clock, though always with due consideration for patients' comfort. Patients are referred either by a physician working in our Institution (medical oncologist, surgeon, or radiotherapist) or by their family physicians. Less frequently, patients themselves specifically ask to be admitted to our Unit. The activity of the Unit itself during its first year of functioning can be summarized as follows. We admitted 155 advanced cancer patients, for a total number of 210 hospitalizations. Patients were admitted a median of 35 months after their diagnosis and a median of 20 days before death. Stays were generally short (median 11 days). We systematically used quantitative assessment tools (MMSQ, MDAS,EFAT and various VAS) to detect and monitor their symptoms and any complications. The main symptoms on admission were pain, anorexia, asthenia, dyspnea and anxiety/depression. Pain, nausea/vomiting, constipation and cough were controlled in almost all patients, whereas control of asthenia and anorexia was most often insufficient. In 51% of our cases the patients could be discharged home; 40% died in the unit; 4% were transferred to long-term palliative care units and 1% to other units within our Institution (4% were still hospitalized at the time of this analysis).

Hypercalcaemia of melanoma: incidence, pathogenesis and therapy with bisphosphonates

Tumour-induced hypercalcaemia (TIH) is a frequent complication of advanced cancer but has been rarely reported in patients with malignant melanoma, and its pathogenesis remains unexplored. We studied eight patients with TIH and melanoma. We determined the incidence and pathogenesis of this complication and the effects of bisphosphonate therapy. The incidence of TIH in 751 patients with melanoma was 1.1%. All patients had liver and bone metastases at the time of hypercalcaemia. All patients had osteolytic lesions, most often multiple. The median survival was 30 days (range 4-136 days). After rehydration, the mean (+/- SEM) corrected calcium was 3.42 +/- 0.17 mmol/l. Parathyroid hormone levels were adequately suppressed and vitamin D concentrations were normal. Serum osteocalcin, a marker of bone formation, was low, except in the two patients with renal insufficiency, whereas fasting urinary calcium and hydroxyproline were increased, indicating inhibition of bone formation and stimulation of bone resorption. Increased parathyroid hormone-related protein secretion was noted in only one patient. Three of four patients became normocalcaemic after bisphosphonate therapy for a median duration of 2 weeks. In conclusion, hypercalcaemia is a rare complication of melanoma. It occurs in the context of far advanced disease and is essentially due to aggressive lytic bone metastases with an uncoupling in bone turnover. Bisphosphonates can offer short-term palliation.

Bisphosphonates in the treatment of metastatic breast cancer

The skeleton is the most common site of metastatic disease in breast cancer and the most common site of first distant relapse. Bone metastases in breast cancer are the source of considerable morbidity, including severe pain, pathological fractures, need for radiotherapy or surgery, and hypercalcemia. Bisphosphonates are potent inhibitors of osteoclast-mediated bone resorption, and it is well known that breast cancer cells in bone can stimulate osteoclast formation and activity leading to the release of growth factors and cytokines, which will further stimulate cancer cell growth and their secretion of osteolytic factors. We are thus typically dealing with a vicious cycle, as the bone resorption-induced release of growth factors from the bone matrix will stimulate breast cancer cell growth (probably mainly by IGFs) and the production of the osteolytic factor PTHrP (probably mainly by TGF-beta but also by extracellular calcium). Clodronate, but not the aminobisphosphonates, can be metabolized to an ATP analog that is toxic for osteoclasts. Nitrogen-containing bisphosphonates, such as pamidronate, ibandronate, and zoledronate, interfere with the mevalonate pathway that is crucial to maintain cell membrane integrity. The net result, regardless of the mechanism, is osteoclast apoptosis, notably through the induction of caspase-3. Bisphosphonates are now the standard treatment for cancer hypercalcemia. Repeated bisphosphonate infusions also exert clinically relevant analgesic effects in at least one half of the patients with metastatic bone pain. Most importantly, prolonged administration of bisphosphonates (for at least 1 year) reduces the frequency of morbid skeletal events by 30-40% in breast cancer metastatic to bone and in up to 50% in patients with multiple myeloma. Newer bisphosphonates, such as ibandronate and zoledronate, will simplify the current therapeutic schemes and improve the cost-effectiveness ratio, and they have the potential to improve the therapeutic efficacy, at least in patients with aggressive osteolytic disease or in the adjuvant setting.

Breast cancer cells release factors that induced apoptosis in human bone marrow stromal cells

Breast cancer is associated frequently with skeletal metastases, which cause significant morbidity. The main mechanism is an increase in osteoclast-mediated bone resorption. We postulated that osteoblasts could be other essential target cells and previously showed that conditioned medium (CM) of breast cancer cells (BCCs) inhibits the proliferation of osteoblast-like cells. In this study, we investigated the effects of BCC-secreted products on osteoprogenitor cells using a clonal fetal human bone marrow stromal preosteoblastic cell line (FHSO-6) that expresses alkaline phosphatase (ALP) activity, type I collagen (COLI), and increased osteocalcin (OC) and osteopontin under treatment with dexamethasone (Dex), 1,25-dihydroxyvitamin D [1,25(OH)2D], or recombinant human bone morphogenetic protein 2 (rhBMP-2). Treatment with MCF-7 CM inhibited FHSO-6 cell survival in a dose-dependent and irreversible manner. Morphological investigation indicated that MCF-7 CM increased both apoptotic and necrotic cell number. MCF-7 CM increased caspases activity and a broad inhibitor of caspase activity (benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethyl ketone [z-VAD-fmk]) partly reversed the CM-induced inhibition of FHSO-6 cell survival. Western blot analyses revealed an increased bax/bcl-2 ratio in MCF-7 CM-treated FHSO-6 cells. MCF-7 cells exhibit FasLigand as membrane-bound protein and as a soluble cytokine in the CM. Deprivation of MCF-7 CM from active FasLigand by saturation with a soluble Fas molecule suppressed the induction of FHSO-6 apoptosis, whereas fibroblast CM, which did not contain FasLigand, only weakly modified FHSO-6 cell survival because of increased cell necrosis. These data indicate that FasLigand secreted by BCCs induces apoptosis and necrosis of human preosteoblastic stromal cells through caspase cascade modulated by the bax and bcl-2 protein level. The induction of apoptosis in human bone marrow stromal cells by BCCs may contribute to the inappropriately low osteoblast reaction and bone formation during tumor-induced osteolysis in bone metastases.

Interleukins-6 and -11 expression in primary breast cancer and subsequent development of bone metastases

Breast cancers frequently metastasize to bone where they often cause extensive tumor-induced osteoclast-mediated osteolysis. Interleukin-6 (IL-6) and IL-11 are two cytokines exhibiting osteolytic properties through their potent stimulation of osteoclast formation. We investigated the expression of IL-6 and IL-11 in 99 invasive primary breast tumors by immunohistochemistry and in situ hybridization, respectively. We examined their potential as predictive factors for further development of bone metastases. 52/90 (57%) of tumor samples showed IL-6 cytoplasmic immunostaining. There was no significant association between IL-6 status and any of the classical prognostic factors. 15/89 (17%) of the tumor samples expressed IL-11 mRNA. A positive IL-11 mRNA status was associated with a low tumor grade (P=0.05). Tumors expressing IL-11 mRNA had a statistically significant (P=0.002) higher rate of bone metastases occurrence (12/15, 80%) than IL-11 negative tumors (27/74, 37%). Such association was not found for IL-6. Our findings demonstrate for the first time IL-11 gene expression in some primary invasive breast tumors and suggest the potential of this cytokine as possible biological predictive factor for the development of bone metastases.

Dosing regimens and main adverse events of bisphosphonates

The bisphosphonates pamidronate and clodronate are most often used in oncology. Newer, more potent compounds under study are ibandronate and zoledronate. The main route of administration is by intravenous infusion (1-2 hours for pamidronate) but oral formulations are or soon will be available for some bisphosphonates (clodronate, ibandronate) and shorter infusion times are being studied (zoledronate, ibandronate). After oral administration of aminobisphosphonates, the main adverse event can be epigastric pain and esophagitis for which the current recommendations include swallowing 180 to 240 mL of water and remaining upright for 30 minutes after tablet ingestion. After intravenous administration, the main adverse events are injection site reaction and flu-like syndrome. Injection site reactions are seen in up to 6% of patients given pamidronate, and this figure is likely to be lower with ibandronate and zoledronate. Flu-like syndrome is seen in up to one third of patients given pamidronate, less with ibandronate, and no figure is yet available for zoledronate. Adverse effects on kidney function were only seen when using a high dose of zoledronate (8 mg over 5-15 minutes) and the current recommended dose is 4 mg given as a 15-minute infusion. Disadvantages of the oral route are poor absorption (<5%) and occasional digestive side effects. With protracted use the size and number of tablets required can reduce compliance. The advantage of oral administration is use on an outpatient basis and it may thus be the preferred route for patients on hormonal therapy and in the adjuvant setting. The main route of administration, however, is currently a 1- to 2-hour intravenous pamidronate infusion, often preferred for patients receiving chemotherapy. The disadvantage of the latter is the need for an appropriate hospital environment. Shorter infusion times are being studied with newer compounds. Intravenous administration is the preferred route for patients receiving chemotherapy. Equivalent intravenous doses to achieve similar success rates in normalizing serum calcium levels are approximately 90 mg, 4 mg, and 2 mg for pamidronate, ibandronate, and zoledronate, respectively. The expectation from the new, more potent compounds is for more convenient therapeutic schemes leading to increased patient compliance and improvements in the reduction of the skeletal morbidity rate and hopefully increase in survival rate.