Assessment of bone response to systemic therapy in an EORTC trial: preliminary experience with the use of collagen cross-link excretion. European Organization for Research and Treatment of Cancer

Intratumoral bacteria are an important "accomplice" in tumor development and metastasis

As emerging tumor components, intratumoral bacteria have been found in many solid tumors. Several studies have demonstrated that different cancer subtypes have distinct microbial compositions, and mechanistic studies have shown that intratumoral bacteria may promote cancer initiation and progression through DNA damage, epigenetic modification, inflammatory responses, modulation of host immunity and activation of oncogenes or oncogenic pathways. Moreover, intratumoral bacteria have been shown to modulate tumor metastasis and chemotherapy response. A better understanding of the tumor microenvironment and its associated microbiota will facilitate the design of new metabolically engineered species, opening up a new era of intratumoral bacteria-based cancer therapy. However, many questions remain to be resolved, such as where intratumoral bacteria originate and whether there is a direct causal relationship between intratumoral bacteria and tumor susceptibility. In addition, suitable preclinical models and more advanced detection techniques are crucial for studying the biological functions of intratumoral bacteria. In this review, we summarize the complicated role of intratumoral bacteria in the regulation of cancer development and metastasis and discuss their carcinogenic mechanisms and potential therapeutic aspects.

Strontium-89 plus zoledronic acid versus zoledronic acid for patients with painful bone metastatic breast cancer

INTRODUCTION

β-ray strontium-89 (Sr-89) intra-irradiation therapy has been approved and clinically used to reduce bone metastasis pain not alleviated by bone-modifying agents, external radiation, and analgesic agents. We examined the efficacy of zoledronic acid (ZOL) and Sr-89 combination therapy compared with ZOL alone in breast cancer patients with bone metastases.

MATERIALS AND METHODS

A randomized controlled trial was conducted on breast cancer patients with bone metastasis to compare the efficacy between ZOL monotherapy and ZOL plus Sr-89 combination therapy. The primary endpoints were changes in urinary NTX levels at 13 weeks and brief pain inventory scores. The secondary endpoints were analgesic drug usages, response rates, changes in bone metabolism markers, quality of life, and adverse event rates.

RESULTS

Thirty of the planned 60 cases were randomly assigned to ZOL alone or ZOL + Sr-89. There were no significant differences in the changes in urinary NTX levels between the 2 groups (P = 0.365). There was no consistent difference in the pain score changes between the 2 groups. Sr-89 addition to ZOL slightly reduced the white blood cell and platelet counts. However, all adverse events were Grade 1. Safety and analgesic drug dose reduction were more evident in ZOL + Sr-89.

CONCLUSION

This trial showed the lack of benefits from Sr-89 addition to ZOL for breast cancer patients with painful bone metastases. However, safety and analgesic drug dose reduction were more evident in ZOL + Sr-89, indicating its potential for pain control. Sr-89 therapy is safe, thus more effective radiopharmaceuticals are anticipated.

The intratumoral microbiome: Characterization methods and functional impact

Live-pathogenic bacteria, which were identified inside tumors hundreds year ago, are key elements in modern cancer research. As they have a relatively accessible genome, they offer a multitude of metabolic engineering opportunities, useful in several clinical fields. Better understanding of the tumor microenvironment and its associated microbiome would help conceptualize new metabolically engineered species, triggering efficient therapeutic responses against cancer. Unfortunately, given the low microbial biomass nature of tumors, characterizing the tumor microbiome remains a challenge. Tumors have a high host versus bacterial DNA ratio, making it extremely complex to identify tumor-associated bacteria. Nevertheless, with the improvements in next-generation analytic tools, recent studies demonstrated the existence of intratumor bacteria inside defined tumors. It is now proven that each cancer subtype has a unique microbiome, characterized by bacterial communities with specific metabolic functions. This review provides a brief overview of the main approaches used to characterize the tumor microbiome, and of the recently proposed functions of intracellular bacteria identified in oncological entities. The therapeutic aspects of live-pathogenic microbes are also discussed, regarding the tumor microenvironment of each cancer type.

Bisphosphonates in Oncology: Physiopathologic Bases and Clinical Activity

Osteoclastic activation is the ultimate way of bone resorption in neoplasia, induced by the combined effects of tumor-secreted humoral factors (especially parathyroid hormone-related peptides) and osteoclastic-osteoblastic interaction. Bisphosphonates inhibit the osteoclast activity and reduce bone resorption and are a valuable supportive measure for bone disease of neoplasms. Experimental models also suggest an activity of bisphosphonates against cancer cells. Controlled studies, especially in advanced breast cancer and multiple myeloma, indicate different effectiveness against the distinct skeletal-related events. Intravenous clodronate and, especially, pamidronate and zoledronate are the first-choice drugs for hypercalcemia, and they play a significant role in reducing metastatic bone pain. Their prolonged use delays, without hampering, the progression of bone disease, including the appearance of osteolysis and the occurrence of pathologic fractures. This effect is probably more valuable when bisphosphonates are administered early in the course of the disease. The evidence that adjuvant bisphosphonates improve survival needs to be confirmed in ongoing studies. Although poorly absorbed by the gastrointestinal tract, oral bisphosphonates are effective in preventing and treating cancer-induced osteoporosis in long-living patients with operable breast cancer. At present, there is little hope that newer bisphosphonates are more effective than those currently used.

Usefulness of Bone Formation Markers in Breast Cancer

The skeleton is the main site affected by metastases and breast cancer is the most frequent tumor to invade bone. The assessment of bone metastases is difficult and biochemical markers of bone formation (BFMs) could be a promising alternative. Although the essential role of osteoblasts in the metastatic process of bone destruction is now well established, little attention has been paid to BFMs. We conducted a Medline search for studies about BFMs in breast cancer. Our review allows us to conclude that BFMs have high specificity but low sensitivity for the diagnosis of bone metastases. The available biochemical markers cannot replace imaging techniques for the diagnosis of bone metastases. Several studies indicate that BFM serum levels reflect total tumor burden in the skeleton. BFM levels are higher in patients with blastic lesions compared to those with lytic lesions. Serial measurements of BFMs could be useful for the clinical assessment of response to antineoplastic treatment or to bisphosphonate therapy. Besides markers of bone resorption, biochemical markers of bone formation are a promising alternative for the assessment of metastatic bone disease, but large prospective studies are needed to address this important issue.

Phase II studies of two different schedules of dasatinib in bone metastasis predominant metastatic breast cancer: SWOG S0622

Bone metastases from breast cancer are common, causing significant morbidity. Preclinical data of dasatinib, an oral small molecule inhibitor of multiple oncogenic tyrosine kinases, suggested efficacy in tumor control and palliation of bone metastases in metastatic breast cancer (MBC). This clinical trial aimed to determine whether treatment with either of 2 dose schedules of dasatinib results in a progression-free survival (PFS) >50 % at 24 weeks in bone metastasis predominant MBC, to evaluate the toxicity of the 2 dosing regimens, and explore whether treatment results in decreased serum bone turnover markers and patient-reported "worst pain." Subjects with bone metastasis predominant MBC were randomly assigned to either 100 mg of dasatinib once daily, or 70 mg twice daily, with treatment continued until time of disease progression or intolerable toxicity. Planned accrual was 40 patients in each arm. The primary trial endpoint was PFS, defined as time from registration to progression or death due to any cause. Median PFS for all eligible patients (79) was 12.6 weeks (95 % CI 9.1-16.7). Neither cohort met the threshold for further clinical interest. There were no significant differences in PFS by randomized treatment arm (p = 0.85). Toxicity was similar in both cohorts, with no clear trend in serum biomarkers of bone turnover or patient-reported pain. Dasatinib was ineffective in controlling bone-predominant MBC in a patient population, unselected by molecular markers. Further study of dasatinib in breast cancer should not be pursued unless performed in molecularly determined patient subsets, or rational combinations.

A phase 2 trial exploring the clinical and correlative effects of combining doxycycline with bone-targeted therapy in patients with metastatic breast cancer

Background

Bone-targeting agents (BTAs), such as bisphosphonates and denosumab, have demonstrated no discernable effects on tumour response or disease free/overall survival in patients with bone metastases from breast cancer. Doxycycline is both osteotropic and has anti-cancer effects. When combined with zoledronate in animal models, doxycycline showed significantly increased inhibition of tumour burden and increased bone formation. We evaluated the effects of adding doxycycline to ongoing anti-cancer therapy in patients with metastatic breast cancer.

Methods

Breast cancer patients with bone metastases and ≥3 months of BTA use, entered this single-arm study. Patients received doxycycline 100 mg orally, twice a day for 12 weeks. The co-primary endpoints were; effect on validated pain scores (FACT-Bone pain and Brief Pain Inventory) and bone resorption markers (serum C-telopeptide, [sCTx]). All endpoints (pain scores, sCTx, bone-specific alkaline phosphatase, skeletal-related events, toxicity) were evaluated at baseline, 4, 8 and 12 weeks. Bone marrow was sampled at baseline and week 12 for exploratory biomarker analysis.

Results

Out of 37 enroled patients, 27 (73%) completed 12 weeks of therapy. No significant changes were seen in pain scores or bone turnover markers. Failure to complete treatment: drug toxicity (70%) and disease progression (30%). Sixteen (43%) patients had GI adverse events.

Conclusions

Doxycycline 100 mg twice daily for 12 weeks had no significant effects on either bone pain or bone turnover markers. Its toxicity profile in this patient population would make further evaluation challenging.

Randomised, phase II, placebo-controlled, trial of fulvestrant plus vandetanib in postmenopausal women with bone only or bone predominant, hormone-receptor-positive metastatic breast cancer (MBC): the OCOG ZAMBONEY study

Biomarkers of bone turnover, including urine N-telopeptide (uNTx), have been used as surrogate measures of response to bone-targeted therapies. Vascular endothelial growth factor (VEGF) levels correlate with extent of bone metastases. We assessed whether vandetanib, an inhibitor of VEGF, epidermal growth factor receptor and RET signalling, improved uNTx response when added to fulvestrant (F) in breast cancer patients with bone metastases. Postmenopausal patients with bone predominant, hormone-receptor-positive metastatic breast cancer were randomised to F (500 mg IM days 1, 15, 29, then monthly) with either vandetanib (100 mg PO OD) (FV) or placebo (FP). The primary objective was uNTx response. Secondary objectives included PFS, OS, RECIST response, pain scores and toxicity. Sixty-one patients were allocated to FV and 68 to FP. Out of 127 analyzable patients, an uNTx response occurred in 66 % for FV and 54 % for FP (p = 0.21). No difference was detected between groups for PFS; HR = 0.95 (95 % CI 0.65-1.38) or OS HR = 0.69 (95 % CI 0.37-1.31). For the 62 patients with measurable disease, clinical benefit rates were 41 and 43 %, respectively (p = 0.47). Serious adverse events were similar, 3.3 % for FV versus 5.9 % for FP. Elevated baseline uNTx (>65 nM BCE/mmol Cr) was prognostic for PFS, HR = 1.55 (95 % CI 1.04-2.30) and for OS, HR = 2.32 (95 % CI 1.25-4.33). The addition of vandetanib to fulvestrant did not improve biomarker response, PFS or OS in patients with bone metastases. Baseline bone turnover was prognostic for PFS and OS.

Assessment of Response to Therapy for Bone Metastases: Is it Still a Challenge in Oncology?

Bone is one of the most common sites of metastases from cancer. Most anticancer treatments are highly toxic but only a fraction of all patients respond to them. Guidelines are needed to evaluate the response in the routine practice of oncology as well as in clinical trials in which new treatment options are evaluated. All current imaging procedures have major limitations. This article reviews old and new criteria for response evaluation. The major problem of accurate response evaluation in bone disease is discussed in detail. Some examples from our daily practice illustrate the difficulties. The indications for bone biopsy are also reviewed.

Lipopolysaccharide-induced expression of matrix metalloproteinases in human monocytes is suppressed by IFN-gamma via superinduction of ATF-3 and suppression of AP-1

Matrix metalloproteinases (MMPs) are induced during inflammatory responses and are important for immune regulation, angiogenesis, wound healing, and tissue remodeling. Expression of MMPs needs to be tightly controlled to avoid excessive tissue damage. In this study, we investigated the regulation of MMP expression by inflammatory factors in primary human monocytes and macrophages. IFN-gamma, which augments inflammatory cytokine production in response to macrophage-activating factors such as TLR ligands, instead broadly suppressed TLR-induced MMP expression. Inhibition of MMP expression was dependent on STAT1 and required de novo protein synthesis. IFN-gamma strongly enhanced TLR-induced expression of the transcriptional repressor activating transcription factor (ATF-3) in a STAT1-dependent manner, which correlated with recruitment of ATF-3 to the endogenous MMP-1 promoter as detected by chromatin immunoprecipitation assays. RNA interference experiments further supported a role for ATF-3 in suppression of MMP-1 expression. In addition, IFN-gamma suppressed DNA binding by AP-1 transcription factors that are known to promote MMP expression and a combination of supershift, RNA interference and overexpression experiments implicated AP-1 family member Fra-1 in the regulation of MMP-1 expression. These results define an IFN-gamma-mediated homeostatic loop that limits the potential for tissue damage associated with inflammation, and identify transcriptional factors that regulate MMP expression in myeloid cells in inflammatory settings.

The use of molecular markers of bone turnover in the management of patients with metastatic bone disease

Biochemical markers of bone turnover are widely used in clinical practice. These indices have been shown to be associated with the occurrence, prognosis and therapeutic response of malignant bone lesions. For example, markers of bone resorption are often elevated in patients with established bone metastases and while this may point to a role of these markers in the diagnostic workup of cancer patients, the available evidence does not permit any final conclusions as to the accuracy and validity of the presently used markers in the early diagnosis of bone metastases. Many bone turnover markers appear to respond to antiresorptive and antineoplastic therapies, and recent evidence from prospective trials suggests that the aim of bisphosphonate therapy should be to normalize rates of bone remodelling to optimize therapeutic and prognostic outcomes. However, it remains unknown whether the use of bone markers in the routine clinical setting has any defined beneficial effects on overall outcome in cancer patients. Clearly, bone turnover markers have insufficient diagnostic or prognostic value to be used in isolation; however, the combination of these markers with other diagnostic techniques may improve clinical assessment of patients with bone-seeking cancers. This article reviews the available evidence (as of August 2007) on the clinical use of bone turnover markers in the management of patients with metastatic bone disease.

Serial Markers of Bone Turnover in Men with Metastatic Prostate Cancer Treated with Zoledronic Acid for Detection of Bone Metastases Progression

OBJECTIVES

This study assessed the usefulness of serial measurements of bone turnover markers in men with metastatic prostate cancer treated with zoledronic acid to detect disease progression.

METHODS

Serum measurements of total alkaline phosphatase (tALP), bone-specific alkaline phosphatase (bALP), cross-linked N-terminal (NTx) and cross-linked C-terminal (CTx) telopeptides of type I collagen, amino-terminal procollagen propeptides of type I collagen (PINP), C-terminal telopeptides of type I collagen (ICTP), and prostate-specific antigen (PSA) were performed in 77 prostate cancer patients suffering from bone metastases and treated with zoledronic acid up to 15 mo. Fifty patients were with and 27 patients without objective evidence of metastatic bone progression during the administration of zoledronic acid.

RESULTS

The baseline bone marker concentrations were not significantly different between the groups. After administration of zoledronic acid all bone markers except of ICTP decreased compared with baseline. CTx showed the greatest decrease. In patients with metastatic bone progression PINP, tALP, bALP, and ICTP were significantly higher at weeks 24, 36, 48, and 60 after starting treatment with zoledronic acid compared with patients without progression. In addition to the information of prostate-specific antigen as a monitoring parameter, the bone formation marker showed a better distinction between patients with and without disease progression.

CONCLUSIONS

Selected bone turnover markers provide valuable information regarding progression of bone metastasis in men with metastatic prostate cancer under bisphosphonate therapy. The clinical impact should be confirmed in prospective randomised studies.

Clinical Utility of Biochemical Markers of Bone Metabolism for Improving the Management of Patients with Advanced Multiple Myeloma

Osteolytic bone lesions from advanced multiple myeloma (MM) result in significant skeletal morbidity. Therefore, biochemical markers of bone metabolism, such as the N-terminal and C-terminal telopeptides of type I collagen, bone-specific alkaline phosphatase, and osteocalcin, have been investigated as tools for evaluating the extent of bone disease, risk of skeletal morbidity, and response to antiresorptive treatment. Several studies have shown that the majority of biochemical markers of bone metabolism are increased in patients with MM with osteolytic bone lesions, thus reflecting changes in bone metabolism associated with tumor growth. There is also a growing body of evidence that markers of bone metabolism correlate with the risk of skeletal complications, disease progression, and death. In addition, bone markers could potentially be used as a tool for early diagnosis of bone lesions. The aim of this review is to improve our understanding of bone markers as a clinical tool for the management of malignant bone disease in patients with MM.

Pilot trial of bone-targeted therapy with zoledronate, thalidomide, and interferon-gamma for metastatic renal cell carcinoma

BACKGROUND

The purpose of the study was to evaluate the efficacy and safety of a bone-targeted regimen consisting of zoledronate, thalidomide, and interferon-gamma in patients with renal cell carcinoma and bone metastases.

METHODS

Eligible patients had radiographic evidence of bone metastasis. Impending pathologic fractures or spinal cord compressions must have been controlled by surgery or radiation therapy before enrollment. Zoledronate (4 mg) was given intravenously every 4 weeks, thalidomide (300 mg) was given orally once a day, and interferon-gamma (100 microg) was given subcutaneously once a week. Patients were evaluated for time to skeletal-related events, the appearance of calcification in osteolytic metastases, and levels of the bone formation/resorption markers. RESULTS.: Fifteen patients were treated between November 2002 and November 2003; 12 had previously undergone surgery, radiation, or embolization for their bone metastases; 11 had more than 3 sites of bone involvement; and 9 also had nonosseous metastases in the lung, liver, lymph node, pancreas, or adrenal gland. The median time to progression was 8.3 weeks (range, 2.1-48 weeks). The median time to a skeletal-related event was 12.0 weeks (range, 3.9-46.4 weeks). Two patients discontinued treatment because of adverse drug reactions (1 deep venous thrombosis and 1 myocardial infarction). Two patients experienced pain improvement and developed calcification in osseous metastases; these patients also showed favorable changes in bone marker levels.

CONCLUSIONS

In this pilot study a bone-targeted regimen combining zoledronate, thalidomide, and interferon-gamma was well tolerated and might provide clinical benefit for a small subset of patients with renal cell carcinoma and bone metastases.

Can bone markers guide more effective treatment of bone metastases from breast cancer?

Bone metastases are a common problem for breast cancer patients, causing significant disease-related morbidity and mortality. Bisphosphonates and other cancer therapies can assist in managing these patients. However, assessing treatment efficacy in bone metastases is hampered by the inability to accurately measure disease response within a clinically desirable time frame. Bone-specific biochemical markers, notably type I collagen telopeptide cross-link by-products such as N-telopeptide (NTx) and C-telopeptide (CTx), have been shown to be effective tools for assessing the severity and extent of bone metastases, and the response to bisphosphonates. Elevated NTx levels correlate with adverse clinical outcomes. Normalization of NTx and CTx excretion rates are associated with relief of symptoms and a reduced incidence of skeletal-related events (SRE). This review discusses the expanding role of these bone markers in guiding treatment of bone metastases from breast cancer.

Clinical use of markers of bone turnover in metastatic bone disease

Bone metastases profoundly perturb normal bone remodeling. Biochemical markers of bone turnover have been shown to reflect these tumor-induced changes in bone remodeling and might therefore be useful in the diagnosis and follow-up of patients with malignant bone disease. Most markers of bone turnover, particularly those of bone resorption, are elevated in patients with established bone metastases. While this might indicate a role for bone markers as diagnostic tools in cancer patients, the available evidence does not provide any final conclusions as to the accuracy and validity of the markers presently used in the early diagnosis of bone metastases. Markers of bone resorption respond promptly and profoundly to bisphosphonate and antineoplastic therapy, and this response is associated with a favorable clinical outcome. Most markers, however, have been more useful in groups of patients monitored in clinical studies than in studies of individuals. While this makes them a good tool for drug development, it remains unknown whether the use of bone markers in a routine clinical setting has any defined beneficial effects on overall outcome in cancer patients. In particular, no study has addressed the question of whether patients with bone metastases should be treated according to their rate of bone turnover and what the treatment goals are in this respect. While it is unlikely that bone-turnover markers have sufficient diagnostic or prognostic value when used in isolation, the combination of these markers with other diagnostic techniques might be the way forward to improve the clinical assessment of patients with cancers of the bone.

Predictive Value of Bone Resorption and Formation Markers in Cancer Patients With Bone Metastases Receiving the Bisphosphonate Zoledronic Acid

Purpose

Three large, randomized trials of patients with bone metastases recently demonstrated that zoledronic acid reduces the risk of skeletal-related events. These trials provide an opportunity for investigating the correlation between bone metabolism and clinical outcome during bisphosphonate therapy.

Patients and Methods

Urinary measurements of N-telopeptide (Ntx) and serum bone alkaline phosphatase (BAP) were obtained in 1,824 bisphosphonate-treated patients—1,462 with zoledronic acid (breast, 490; prostate, 411; myeloma, 210; non–small-cell lung, 183; other, 168) and 362 with pamidronate (breast, 254; myeloma, 108). This exploratory cohort analysis grouped patients by baseline and most recent levels of Ntx as low (< 50 nmol/mmol creatinine), moderate (50 to 99 nmol/mmol creatinine), or high (≥ 100 nmol/mmol creatinine), and BAP as low (< 146 U/L) or high (≥ 146 U/L). The relative risks for negative clinical outcomes were estimated for each group using multiple-event and Cox regression models with time-varying covariates.

Results

Patients with high and moderate Ntx levels had 2-fold increases in their risk of skeletal complications and disease progression compared with patients with low Ntx levels (P < .001 for all). High Ntx levels in each solid tumor category were associated with a 4- to 6-fold increased risk of death on study, and moderate Ntx levels a 2- to 4-fold increased risk compared with low Ntx levels (P < .001 for all). Bone alkaline phosphatase also showed some correlation with risk of negative clinical outcomes.

Conclusion

The bone resorption marker Ntx provides valuable prognostic information in patients with bone metastases receiving bisphosphonates.

Assessment of therapeutic response in patients with metastatic bone disease

Metastatic bone disease is common in cancer patients and causes substantial disease-related morbidity and mortality. However, several effective treatments are available for the management of these patients. Bisphosphonates, which inhibit osteoclast-mediated resorption of bone matrix, are especially important because they decrease the incidence of skeletal-related events in many tumour types and can complement antineoplastic therapies. At present, assessment of treatment for bone metastases is hindered by a lack of effective, rapid methods to measure disease response. We discuss the difficulties of current measures of response assessment and describe the development of new radiological and biochemical markers of bone metastases. Assays that detect type I collagen telopeptides as markers of bone resorption seem to be most promising at present.

Clinical review 165: Markers of bone remodeling in metastatic bone disease

Many cancers have a strong propensity to spread to bone. The processes involved in cancer dissemination to bone are complex and variable, and the changes in bone metabolism, once bony metastases have occurred, are usually profound. This review surveys the usefulness of bone markers in the diagnosis and follow-up of patients with malignant bone disease. In patients with established bone metastases, most markers of bone remodeling are abnormal compared with healthy controls or cancer patients without bone lesions. Although bone markers may have a potential as diagnostic tools in cancer patients, the available data do not allow final conclusions regarding the accuracy and validity of any of the presently used markers in the diagnosis of bone metastases. As regards monitoring of anticancer therapy, most markers of bone remodeling respond to active treatments. These indices therefore may have the potential to be used in the monitoring of antitumor therapies. However, most if not all of the available evidence on the use of bone markers in monitoring anticancer therapy is observational, and it remains unclear whether they have any beneficial effects on overall outcome. The same is true for their prognostic value, although evidence suggests that suppressed levels of bone formation or high rates of bone resorption are independent predictors of poor survival.

Efficacy of zoledronic acid and pamidronate in breast cancer patients: a comparative analysis of randomized phase III trials

Results of a large, randomized, comparative phase III trial involving 1,130 breast cancer patients demonstrated that 4 mg zoledronic acid and 90 mg pamidronate were equally effective at reducing the occurrence and delaying the onset of skeletal-related events in patients with bone metastases secondary to breast cancer. However, zoledronic acid has demonstrated a treatment advantage over pamidronate with respect to the proportion of patients receiving radiation therapy to bone. Moreover, among patients with at least one osteolytic lesion (N = 352), zoledronic acid achieved a 17% reduction in the proportion of patients with a skeletal-related event compared with pamidronate and significantly prolonged the time to first event. In general, zoledronic acid and pamidronate had comparable effects on time to progression of bone metastases, overall disease progression, pain and analgesia scores, and overall survival. Both zoledronic acid and pamidronate effectively suppressed markers of bone resorption. However, zoledronic acid demonstrated a greater and more sustained suppressive effect. Zoledronic acid (4 mg via 15-minute infusion) also demonstrated a safety profile similar to that of pamidronate (90 mg via 2-hour infusion). In summary, the increased efficacy of zoledronic acid in specific patient subsets and the convenience of a 15-minute infusion suggest that 4 mg zoledronic acid has advantages over 90 mg pamidronate for treatment of bone metastases in patients with breast cancer.

Assessment of the effects of breast cancer on bone and the response to therapy

The skeleton is the most frequent site of metastatic disease in breast cancer and also the site of greatest morbidity. In addition, there is now recognition that accelerated bone loss associated with chemotherapy or hormonal therapy leads to an increased risk of osteoporosis in long-term breast cancer survivors. An improved range of treatment options is available and assessment of skeletal response both to the disease and to therapy is therefore of growing importance. Plain radiographs remain widely used to assess response, but are of limited sensitivity. The isotope bone scan is more sensitive, but lacks specificity. Computerised tomography, magnetic resonance imaging and positron emission tomography all have an increasing role. In treatment-induced osteoporosis, bone mineral density is now readily measured by DEXA scanning. Tumour markers such as CEA, CA 15-3, CA 549 and TPA may have a role in assessing response, but probably in combination rather than individually, using an appropriate quantitative model. Several trials have shown that bone markers, especially markers of bone resorption such as Ntx, Ctx, PYD and DPD, appear to have strong potential as rapid, convenient and inexpensive measures of response. There is also evidence that they may be used as predictive or prognostic indicators. Evidence is accumulating that the reduction of bone resorption markers into the normal range results in substantially reduced morbidity in metastatic breast cancer and that this should be a major target of therapy.

The clinical use of bone resorption markers in patients with malignant bone disease

BACKGROUND

Advanced tumors often metastasize to bone, resulting in a variety of skeletal complications. Bisphosphonates are potent inhibitors of osteoclast-mediated bone resorption that reduce the incidence and delay the onset of skeletal complications and reduce the need for radiation and surgery. Biochemical markers of bone resorption have been identified that can augment the imaging techniques used to diagnose bone metastases and assess response to bisphosphonate therapy.

METHODS

In the current study, the available literature regarding bone resorption markers is reviewed and the clinical relevance of these data with respect to the treatment of bone metastases discussed.

RESULTS

Urinary calcium and hydroxyproline have been widely used to assess bone metabolism, but do not appear to be well correlated with clinical outcome in patients with bone metastases. Several unique breakdown products of Type I collagen (including pyridinium crosslinks, pyridinoline, and deoxypyridinoline) and peptide-bound crosslinks (N-telopeptide and C-telopeptide) are more specific and sensitive markers of bone resorption. N-telopeptide and C-telopeptide have been identified as the most sensitive biochemical markers currently available for detecting bone metastases and for assessing response to therapy or disease progression.

CONCLUSIONS

To the author's knowledge markers of bone resorption have not yet been recommended for routine clinical use. However, further research is needed to define their potential role in the diagnosis of bone metastases, the assessment of disease progression and response to bisphosphonate therapy, and predict the rate of bone loss and the potential for fracture. Suppression of bone resorption markers in response to bisphosphonate therapy appears to correlate with clinical outcome in patients with both osteolytic and blastic bone lesions; therefore, the goal of bisphosphonate therapy should be to suppress markers of bone resorption.

Prospective evaluation of the peptide-bound collagen type I cross-links N-telopeptide and C-telopeptide in predicting bone metastases status

PURPOSE

The objective assessment of bone metastases is currently based on serial changes in skeletal survey. We performed a prospective study to determine whether a correlation exists between the biochemical markers of bone turnover and x-ray evaluation of bone metastases in patients with or without bisphosphonate therapy, and whether bone markers are influenced by extraskeletal disease.

PATIENTS AND METHODS

Patients with either bone or extraskeletal metastases were consecutively enrolled and World Health Organization response criteria were applied for both bone and extraosseous disease every 3 to 4 months. Serum levels of bone-specific alkaline phosphatase (B-AP) and C-telopeptide (ICTP) and urine levels of N-telopeptide (NTX) were measured monthly. The data were analyzed by generalized estimation equation regression.

RESULTS

We studied 97 patients with bone metastases (52 also with extraskeletal metastases) and 26 with extraosseous disease only. Median time on study was 153 days, and 281 objective evaluations (171 in bone) were performed. With bisphosphonates (49 patients receiving pamidronate and three receiving clodronate), percent change from levels without therapy was 47% for NTX (P <.001) and 69% for B-AP (P =.008). With disease progression in bone, percent change from mean levels during stable disease was 152% for NTX (P <.001) and 144% for ICTP (P <.001) regardless of bisphosphonate therapy. NTX had the highest positive predictive value (71%) for the diagnosis of bone metastases progression. Extraskeletal disease had no significant effect on bone markers.

CONCLUSION

Urinary NTX may be a valuable bone marker to assess the antiresorptive effect of bisphosphonate therapy and to evaluate the progression of bone metastases.

The clinical and cost considerations of bisphosphonates in preventing bone complications in patients with metastatic breast cancer or multiple myeloma

The bisphosphonates are potent inhibitors of osteoclast-mediated bone resorption and are now the treatment of choice for the management of hypercalcaemia of malignancy. The incidences of hypercalcaemia and other skeletal complications (bone pain, pathological fracture) remain high despite apparent responses to systemic therapy, with particularly high event rates in women with advanced skeletal metastases of breast cancer. This review focuses on studies addressing the long-term efficacy of bisphosphonates to reduce skeletal complications in breast cancer (5 studies) and multiple myeloma (4 studies), with particular reference to controlled studies of sufficient magnitude and duration to allow confidence in the estimation of efficacy. Bearing in mind the limitations of differences in trial design and the lack of direct studies comparing drugs, adequate exposure to a bisphosphonate reduces the incidence of skeletal complication by 30 to 40% in both breast cancer and multiple myeloma. Oral clondronate and intravenous pamidronate have similar efficacy in both diseases, but the duration of efficacy may differ between drugs. Both agents have shown intriguing survival benefits in subgroups of patients. The numbers needed to treat (NNT) to prevent a skeletal complication during one year are lowest in metastatic skeletal disease in breast cancer (NNT < 8) but also compare very favourably with other disease for patients with recurrent nonskeletal breast cancer or multiple myeloma (NNTs 7 to 31 depending on the complication to be prevented). Treatment costs of both breast cancer and multiple myloma are driven by inpatient and outpatient hospital visits so that bisphosphonate regimens should be developed that reduce both. Further research is required to determine if subgroups of patients can be better identified that will derive particular benefit, or perhaps no benefit at all, from bisphosphonate therapy. It is not known whether more potent bisphosphonates will deliver greater clinical efficacy in the future.

Assessment of response to systemic therapy focusing on metastatic bone disease

The 25-year-old rules for response evaluation developed by UICC and WHO still remain the cornerstone for response evaluation and documentation of treatment effects from systemic cancer treatment. Often, however, plain radiographs are insensitive to changes in tumour growth and disagree with clinical findings. Other methods of evaluation, such as biochemical markers and newer imaging technology may provide valuable additional information in these cases.

Bone markers in the management of metastatic bone disease

Newer markers of bone formation and bone resorption are now available. Alone these new markers do not appear to be useful to diagnose metastatic bone disease. Several markers appear to be of prognostic importance and correlate with the extent of tumour in the skeleton. Serial monitoring of bone markers may be useful to monitor the efficacy of bisphosphonate and/or systemic therapy of both lytic and blastic bone metastases.

A Phase I, open label, dose ranging trial of intravenous bolus zoledronic acid, a novel bisphosphonate, in cancer patients with metastatic bone disease

BACKGROUND

Bone metastases typically are associated with osteolytic bone destruction, resulting in bone pain, pathologic fractures, spinal cord compression, and hypercalcemia. Bisphosphonates are potent inhibitors of normal and pathologic bone resorption and represent a significant therapeutic improvement in the management of patients with lytic bone metastases. Zoledronic acid is a new-generation, highly potent, nitrogen-containing bisphosphonate that to the authors knowledge is the most potent inhibitor of bone resorption currently in clinical trials. The objectives of the current study were to assess the safety and tolerability of increasing doses of zoledronic acid and to determine its activity with respect to reducing biochemical markers of bone resorption in cancer patients with bone metastases.

METHODS

Forty-four cancer patients with bone metastases or primary bone lesions were enrolled sequentially into 1 of 5 fixed ascending-dose treatment groups. Each patient received a single intravenous bolus injection of 1, 2, 4, 8, or 16 mg of zoledronic acid over 30-60 seconds. Patients were monitored for 8 weeks for the evaluation of clinical findings, adverse events, vital signs, electrocardiograms, markers of bone resorption, and urinary N-acetyl-beta-D-glucosaminidase.

RESULTS

Zoledronic acid was safe and well tolerated at all dose levels tested. Commonly reported adverse events included bone pain, fever, anorexia, constipation, and nausea, which were experienced by a similar proportion of patients in each treatment group. Seven patients reported serious adverse events, none of which appeared to be related to the study drug. Zoledronic acid effectively suppressed biochemical markers of bone resorption, including the highly specific markers N-telopeptide and deoxypyridinoline, for up to 8 weeks in the 2-16-mg dose groups and for a shorter duration in the 1-mg group.

CONCLUSIONS

In the current study, zoledronic acid was safe and well tolerated and demonstrated potent inhibition of bone resorption. The authors believe it may improve the treatment of metastatic bone disease.