Randomized, placebo-controlled trial of clodronate in patients with primary operable breast cancer

Prevention of bone loss by zoledronic acid in premenopausal women undergoing adjuvant chemotherapy persist up to one year following discontinuing treatment

CONTEXT

Adjuvant chemotherapy is associated with significant reductions in bone mineral density (BMD) in premenopausal women with breast cancer (BC) that is prevented with zoledronic acid (ZA) every 3 months for 1 yr.

OBJECTIVE

The aim of the study was to examine the effect on BMD of discontinuing ZA during the subsequent year.

DESIGN

We conducted a randomized, double-blind trial.

PATIENTS

Premenopausal women (mean age, 42 yr) undergoing adjuvant chemotherapy for BC participated in the study.

INTERVENTION

ZA (4 mg iv every 3 months) vs. placebo was administered for 12 months.

OUTCOME MEASURES

We measured percentage change in BMD and bone turnover markers at 12 and 24 months (1 yr after last infusion).

RESULTS

Of 101 women randomized, 85 completed 12-month and 62 completed 24-month evaluations. In the placebo group, serum C-telopeptide (CTX) increased progressively over the first 12 months, returned toward baseline but remained significantly above baseline by 24 months. Lumbar spine BMD decreased from baseline by 5.5% at 12 and 6.3% at 24 months. Similarly, by 24 months, total hip and femoral neck BMD declined by 2.6 and 2.4%, respectively. In ZA patients, BMD remained stable (P < 0.0001 compared to placebo). Serum CTX declined significantly by 6 months, but returned to baseline by 12 months, remaining there at 24 months.

CONCLUSIONS

Premenopausal women receiving chemotherapy for BC sustained significant bone loss during the first year, without recovery during the second year. ZA effectively prevented bone loss during the first year of chemotherapy. BMD remained stable 1 yr after completion of ZA. Serum CTX increased significantly by 12 and 24 months. More frequent administration may be required to suppress bone resorption in this patient population.

Bisphosphonates in breast cancer: teaching an old dog new tricks

PURPOSE OF REVIEW

Bisphosphonates are potent inhibitors of bone resorption that reduce the risk of skeletal complications and prevent treatment-induced bone loss. However, recent data suggest that bisphosphonate use in breast cancer may provide more than just supportive care and modify the course of the disease by disrupting the metastatic process.

RECENT FINDINGS

Research in the metastatic setting is focused on refining treatment, using bone markers to identify high-risk patients and define optimal schedules, potentially leading to personalized therapy. In the prevention of cancer treatment-induced bone loss (CTIBL), a large number of studies have demonstrated the efficacy of oral and intravenous bisphosphonates and recent guidelines have defined management strategies for CTIBL. Preclinical studies have reported direct antitumour effects of bisphosphonates, particularly in combination with chemotherapy. In the clinical setting the antitumour effect is less clear, but recent data suggest that zoledronic acid may modify the course of the disease and reduce disease recurrence.

SUMMARY

Bisphosphonates are comprehensively established in the treatment of metastatic bone disease and significantly reduce skeletal morbidity. Their role in the prevention of cancer treatment-induced bone disease is also defined. The potential antitumour and disease-modifying role of adjuvant bisphosphonates holds promise but results from ongoing studies must be awaited before this becomes standard practice.

CXCR4 expression in early breast cancer and risk of distant recurrence

BACKGROUND

Chemokine receptor 4 (CXCR4) has been demonstrated to have a critical role in the early metastatic process. The aim of this study was to evaluate the prognostic value of CXCR4 expression in primary breast tumors and describe correlations with the occurrence of metastasis in organs expressing the CXCR4 ligand stromal cell-derived factor 1 (i.e., liver, lung, brain, and bone).

PATIENTS AND METHODS

CXCR4 expression in primary breast tumors was evaluated by immunohistochemistry in 823 patients included in two prospective clinical trials. CXCR4 expression was considered positive when >1% of tumor cells were stained. The prognostic value of CXCR4 expression was assessed by a Cox regression model adjusted for clinical characteristics. We assessed the association of CXCR4 expression with the rate of distant metastasis to specific organ sites.

RESULTS

CXCR4 was expressed in 92 of 794 primary tumors (12%). CXCR4 expression was not associated with clinical characteristics. CXCR4 was not prognostic for overall survival and showed a nonsignificant trend toward a higher risk for distant metastasis. CXCR4(+) tumors showed a significantly higher risk for bone metastasis. The 10-year incidences of bone metastases were 23% (13.6%-32.6%) and 12% (9.7%-15%) in CXCR4(+) and CXCR4(-) tumors, respectively.

CONCLUSION

This study suggests that expression of CXCR4 in primary breast tumors is associated with a higher likelihood of developing bone metastases. This finding could open new avenues for the development of novel adjuvant strategies, including bone-targeting agents.

Ten-year follow-up of a randomized controlled trial of adjuvant clodronate treatment in node-positive breast cancer patients

Ten-year follow-up results are presented of an adjuvant clodronate trial in patients with primary breast cancer. Between 1990 and 1993, 299 women with primary node positive breast cancer were randomized to oral clodronate 1600 mg daily (149) or controls (150) for 3 years. All patients received adjuvant chemo- or endocrine therapy. Within 10 years bone metastases were detected at the same frequency in the clodronate and control groups: 44 (32%) vs. 42 (29%), respectively, (p=0.35). The frequency of non-skeletal recurrences (visceral and local) was significantly higher in the clodronate group 69 (50%) as compared with the controls 51 (36%) (p=0.005). Ten-year disease-free survival (DFS) remained significantly lower in the clodronate group (45% vs. 58%, p=0.01, respectively). This was especially seen in oestrogen receptor negative patients (25% vs. 58%, p=0.004, respectively). No significant overall survival difference was found between the groups. As previously reported 3-year adjuvant clodronate treatment did not prevent the development of bone metastases in node-positive breast cancer patients. A negative effect of clodronate on DFS by increasing the development of visceral metastases was still seen at 10 years, but this did not significantly compromise overall survival.

Bisphosphonate treatment in primary breast cancer: results from a randomised comparison of oral pamidronate versus no pamidronate in patients with primary breast cancer

PURPOSE AND PATIENTS

During the period from January 1990 to January 1996 a total of 953 patients with lymph node negative primary breast cancer were randomised to oral pamidronate (n=460) 150 mg twice daily for 4 years or no adjuvant pamidronate (n=493) in order to investigate whether oral pamidronate can prevent the occurrence of bone metastases and fractures. The patients received adjuvant chemotherapy, loco-regional radiation therapy, but no endocrine treatment.

RESULTS

During the follow-up period the number of patients with pure bone metastases was 35 in the control group and 31 in the pamidronate group. The number of patients with a combination of bone and other distant metastases were 22 in the control group and 20 in the pamidronate group. The hazard rate ratio for recurrence in bone in the pamidronate group compared to the control group was 1.03 (95% confidence interval 0.75-1.40) and p=0.86. No effect was observed on overall survival. In a small subgroup of 27 patients from the study, 12 of whom were treated with pamidronate a significant bone preserving effect was observed on bone mineral density in the lumbar spine, but not in the proximal femur.

CONCLUSION

The results from the trial do not support a beneficial effect of oral pamidronate on the occurrence of bone metastases or fractures in patients with primary breast cancer receiving adjuvant chemotherapy.

Recommendations for research priorities in breast cancer by the Coalition of Cancer Cooperative Groups Scientific Leadership Council: systemic therapy and therapeutic individualization

Over 9,000 women with breast cancer are enrolled annually on clinical trials sponsored by the National Cancer Institute (NCI), accounting for about one-third of all patients enrolled on NCI-sponsored trials. Thousands are also enrolled on pharmaceutical-sponsored studies. Although breast cancer mortality rates have recently declined for the first time in part due to systemic therapeutic advances, coordinated efforts will be necessary to maintain this trend. The Coalition of Cancer Cooperative Groups convened the Scientific Leadership Council in breast cancer (BC), an expert panel, to identify priorities for future research and current trials with greatest practice-changing potential. Panelists formed a consensus on research priorities for chemoprevention, development and application of molecular markers for predicting therapeutic benefit and toxicity, intermediate markers predictive of therapeutic effect, pathogenesis-based therapeutic approaches, utilization of adaptive designs requiring fewer patients to achieve objectives, special and minority populations, and effects of BC and treatment on patients and families. Panelists identified 13 ongoing studies as High Priority and identified gaps in the current trial portfolio. We propose priorities for current and future clinical breast cancer research evaluating systemic therapies that may serve to improve the efficiency of clinical trials, identify individuals most likely to derive therapeutic benefit, and prioritize therapeutic strategies.

Chemokine receptor CXCR4 expression in hepatocellular carcinoma patients increases the risk of bone metastases and poor survival

Background

The chemokine and bone marrow-homing receptor CXCR4 is implicated in metastases of various cancers. This study was conducted to analyze the association of CXCR4 expression with hepatocellular carcinoma (HCC) bone metastasis and patient survival.

Methods

Tumor tissue from HCC patients with (n = 43) and without (n = 138) bone metastasis was subjected to immunohistochemical staining for CXCR4 using tissue microarrays. Immunoreactivity was evaluated semi-quantitatively. A receiver-operating characteristic-based approach and logistical regression analysis were used to determine the predictive value of clinicopathologic factors, including CXCR4 expression, in bone metastasis. Patient survival was analyzed by Kaplan-Meier curves and log-rank tests.

Results

CXCR4 overexpression was detected in 34 of 43 (79.1%) patients with bone metastases and in 57 of 138 (41.3%) without bone metastases. CXCR4 expression correlated with (correlation coefficient: 0.551, P < 0.001) and was predictive of HCC bone metastases (AUC: 0.689; 95%CI: 0.601 – 0.776; P < 0.001). CXCR4 staining intensity correlated with the bone metastasis-free survival (correlation coefficient: -0.359; P = 0.018). CXCR4 overexpression in primary tumors (n = 91) decreased overall median survival (18.0 months vs. 36.0 months, P <0.001). Multivariable analysis identified CXCR4 as a strong, independent risk factor for reduced disease-free survival (relative risk [RR]: 5.440; P = 0.023) and overall survival (RR: 7.082; P = 0.001).

Conclusion

CXCR4 expression in primary HCCs may be an independent risk factor for bone metastasis and may be associated with poor clinical outcome.

Potential antitumor effects of nitrogen-containing bisphosphonate in hormone receptor negative breast cancer patients with bone metastases

BACKGROUND

This retrospective study evaluated, according to hormone receptor status, the antitumor effects of bisphosphonate especially on survival and disease progression in breast cancer patients with metastatic bone disease.

METHODS

Of 317 patients with initial bone metastasis and known breast cancer subtypes, 230 patients (72.6%) had hormone receptor (HR) positive tumors, and 87 patients (27.4%) had HR negative tumors. We assessed the primary outcome of overall survival (OS), after adjusting for other factors, comparing a group that received bisphosphonates (BPs) with a group that did not receive it.

RESULTS

87.8% of HR positive and 69.0% of HR negative patients received BPs with a median number of 17.7 cycles. Although BPs treatment made no survival benefit in HR positive group, HR negative patients showed a significant prolonged survival when they received BPs treatment (hazard ratio = 0.56 [95% CI 0.34 to 0.91], P = 0.019). In multivariate analysis, disease free interval > 2 years (P = 0.036), a sum of metastatic sites < 3 (P = 0.034), and BP treatments (P = 0.007) were significant factors for survival in HR negative patients.

CONCLUSION

Bisphosphonate treatment can result in a survival benefit in metastatic breast cancer patients with HR negative tumors.

Adjuvant bisphosphonate therapy for breast cancer patients: Standard of care or future direction?

Bone is the most common site of metastatic spread in breast cancer patients. The use of bisphosphonates (BPs) in women with bone metastases from breast cancer has been shown to reduce the incidence, and delay the onset of, skeletal-related events. Indeed, BPs are now an established standard of care in treating patients with bone metastases. As with many new therapies, once efficacy in the metastatic setting is demonstrated, therapies are tested in the adjuvant setting. There are a number of trials that have tested the hypothesis that BP therapy in women with early breast cancer may not only reduce the development of skeletal metastases but also improve both disease-free and overall survival; recent randomized trials have demonstrated intriguing results regarding the possible anticancer effects of adjuvant BP therapy. Furthermore, interesting signals are filtering through from trials evaluating the role of BPs to prevent cancer-treatment induced bone loss. Many of these trials will be reported in the near future. In this article we review possible subgroups that may benefit from adjuvant treatment with BPs, and ongoing trials that may offer more definitive answers.

Treatment Options for Breast Cancer and Bone Metastases

The most common destination for breast cancer metastases is bone. If bone metastases are detected, treatment algorithms should include the continuation of cytoreductive therapy with the addition of treatment to counter skeletal-related events, including bone pain. The range of current treatment options includes bisphosphonates, surgical intervention to improve structural integrity and palliative focal radiotherapy. This article focuses on the role of bisphosphonate therapy in metastatic breast cancer. Bisphosphonate therapy significantly reduces the impact of skeletal-related events, reduces bone pain and increases patient quality of life. Our current understanding is that bisphosphonates may also disrupt the metastatic process and reduce the development of bone lesions. Ultimately, this may lead to further expansion of bisphosphonate-based therapy in the future.

Exploring the anti-tumour activity of bisphosphonates in early breast cancer

Bisphosphonates are potent inhibitors of osteoclast-mediated bone resorption and are firmly established in the management of breast cancer patients with metastatic skeletal disease. There are extensive data that bisphosphonates, particularly nitrogen-containing bisphosphonates such as zoledronic acid, exhibit anti-tumour activity potentially via both indirect and direct mechanisms in vitro. In vivo studies using animal models of breast cancer induced bone disease have shown that bisphosphonates exert anti-tumour effects via inhibiting osteolysis and reducing skeletal tumour burden. Furthermore, pre-clinical studies have demonstrated synergistic anti-tumour effects between chemotherapy agents commonly used in breast cancer treatment and nitrogen-containing bisphosphonates. This, coupled with emerging evidence from pre-clinical in vivo studies suggesting that bisphosphonates may have additional anti-tumour activity outside of the bone microenvironment, could be of significant importance in the clinical management of breast cancer. The evidence in favour of an anti-tumour effect of bisphosphonates in the clinical setting is inconclusive however, with conflicting evidence from several trials. This review focuses on the anti-tumour activity of bisphosphonates in breast cancer, with particular focus on zoledronic acid. The pre-clinical evidence for anti-tumour activity will be reviewed, followed by the synergistic effects with anti-cancer agents. Finally, the clinical relevance and strategies for the evaluation of anti-tumour activity in breast cancer will be discussed. We are currently exploring the potential synergistic anti-tumour effects of the sequential treatment of neoadjuvant chemotherapy followed by zoledronic acid in a randomised phase II study evaluating biological endpoints including apoptosis, proliferation and angiogenesis in patients with breast cancer.

Bisphosphonates: mechanism of action and role in clinical practice

Bisphosphonates are primary agents in the current pharmacological arsenal against osteoclast-mediated bone loss due to osteoporosis, Paget disease of bone, malignancies metastatic to bone, multiple myeloma, and hypercalcemia of malignancy. In addition to currently approved uses, bisphosphonates are commonly prescribed for prevention and treatment of a variety of other skeletal conditions, such as low bone density and osteogenesis imperfecta. However, the recent recognition that bisphosphonate use is associated with pathologic conditions including osteonecrosis of the jaw has sharpened the level of scrutiny of the current widespread use of bisphosphonate therapy. Using the key words bisphosphonate and clinical practice in a PubMed literature search from January 1, 1998, to May 1, 2008, we review current understanding of the mechanisms by which bisphosphonates exert their effects on osteoclasts, discuss the role of bisphosphonates in clinical practice, and highlight some areas of concern associated with bisphosphonate use.

Adjuvant oral clodronate improves the overall survival of primary breast cancer patients with micrometastases to the bone marrow: a long-term follow-up

BACKGROUND

Adding oral clodronate to postoperative adjuvant breast cancer therapy significantly improves disease-free survival (DFS) and overall survival (OS). Long-term follow-up data from the prospective, randomized, controlled study are reported.

PATIENTS AND METHODS

Patients with primary breast cancer received clodronate 1600 mg/day for 2 years or no treatment along with standard adjuvant breast cancer treatment.

RESULTS

Analysis of 290 of 302 patients demonstrated that a significant improvement in OS was maintained in the clodronate group at a median follow-up of 103 +/- 12 months; 20.4% of patients in the clodronate group versus 40.7% of control group patients (P = 0.04) died during the 8.5 years following primary surgical therapy. Significant reductions in the incidence of bony and visceral metastases and improvement in duration of DFS at 36- and 55-month follow-up periods were no longer seen with clodronate.

CONCLUSION

These long-term survival data extend the survival advantage reported in previous studies with oral clodronate in breast cancer.

The bone microenvironment in metastasis; what is special about bone?

The skeleton is a common destination for many cancer metastases including breast and prostate cancer. There are many characteristics of bone that make it an ideal environment for cancer cell migration and colonization. Metaphyseal bone, found at the ends of long bone, in ribs, and in vertebrae, is comprised of trabecular bone interspersed with marrow and rich vasculature. The specialized microvasculature is adapted for the easy passage of cells in and out of the bone marrow. Moreover, the metasphyseal regions of bone are constantly undergoing remodeling, a process that releases growth factors from the matrix. Bone turnover also involves the production of numerous cytokines and chemokines that provide a means of communication between osteoblasts and osteoclasts, but co-incidentally can also attract and support metastatic cells. Once in the marrow, cancer cells can interact directly and indirectly with osteoblasts and osteclasts, as well as hematopoietic and stromal cells. Cancer cells secrete factors that affect the network of cells in the bone microenvironment as well as interact with other cytokines. Additionally, transient cells of the immune system may join the local mileau to ultimately support cancer cell growth. However, most metastasized cells that enter the bone marrow are transient; a few may remain in a dormant state for many years. Advances in understanding the bone cell-tumor cell interactions are key to controlling, if not preventing metastasis to bone.

Bone health issues in women with early-stage breast cancer receiving aromatase inhibitors

Bone health is an important issue for women with all stages of breast cancer, but especially those with early-stage breast cancer receiving aromatase inhibitors (AIs). AIs have been shown to reduce bone mineral density and are associated with an increased incidence of fractures. Although AIs significantly improve survival times in early-stage breast cancer patients, many of these patients eventually develop metastatic bone disease. Therefore, identifying effective strategies for preventing bone metastases is needed. Results of preclinical studies with bisphosphonates show increased tumor cell kill in several breast cancer cell lines, but study results evaluating this class of drugs for prevention of bone metastases in women with early-stage breast cancer receiving adjuvant therapies have been inconsistent. However, several large studies to clarify the role of bisphosphonates in maintaining or improving bone health in these women are under way.

Metastasis: a therapeutic target for cancer

Metastasis remains the major driver of mortality in patients with cancer. Our growing body of knowledge regarding this process provides the basis for the development of molecularly targeted therapeutics aimed at the tumor cell or its interaction with the host microenvironment. Here we discuss the similarity and differences between primary tumors and metastases, pathways controlling the colonization of a distant organ, and incorporation of antimetastatic therapies into clinical testing.

Alendronate decreases orthotopic PC-3 prostate tumor growth and metastasis to prostate-draining lymph nodes in nude mice

Background

Metastatic prostate cancer is associated with a high morbidity and mortality but the spreading mechanisms are still poorly understood. The aminobisphosphonate alendronate, used to reduce bone loss, has also been shown to inhibit the invasion and migration of prostate cancer cells in vitro. We used a modified orthotopic PC-3 nude mouse tumor model of human prostate cancer to study whether alendronate affects prostate tumor growth and metastasis.

Methods

PC-3 cells (5 × 10⁵) were implanted in the prostates of nude mice and the mice were treated with alendronate (0.5 mg/kg/day in PBS, s.c.) or vehicle for 4 weeks. After sacrifice, the sizes of tumor-bearing prostates were measured and the tumors and prostate-draining regional iliac and sacral lymph nodes were excised for studies on markers of proliferation, apoptosis, angiogenesis and lymphangiogenesis, using histomorphometry and immunohistochemistry.

Results

Tumor occurrence in the prostate was 73% in the alendronate-treated group and 81% in the control group. Mean tumor size (218 mm³, range: 96–485 mm³, n = 11) in the alendronate-treated mice was 41% of that in the control mice (513 mm³, range: 209–1350 mm³, n = 13) (p < 0.05). In the iliac and sacral lymph nodes of alendronate-treated mice, the proportion of metastatic area was only about 10% of that in control mice (p < 0.001). Immunohistochemical staining of tumor sections showed that alendronate treatment caused a marked decrease in the number of CD34-positive endothelial cells in tumors (p < 0.001) and an increase in that of ISEL positive apoptotic cells in tumors as well as in lymph node metastases (p < 0.05) compared with those in the vehicle-treated mice. The density of m-LYVE-1-stained lymphatic capillaries was not changed.

Conclusion

Our results demonstrate that alendronate treatment opposes growth of orthotopic PC-3 tumors and decreases tumor metastasis to prostate-draining lymph nodes. This effect could be at least partly explained by decreased angiogenesis and increased apoptosis. The results suggest that bisphosphonates have anti-tumoral and anti-invasive effects on primary prostate cancer.

Molecular mechanisms and treatment of bone metastasis

The metastasis of cancer cells to bone alters bone architecture and mineral homeostasis. As described by the 'seed and soil' hypothesis, bone represents a fertile ground for cancer cells to flourish. A 'vicious cycle' of reciprocal bone-cancer cellular signals occurs with osteolytic (bone-resorbing) metastases, and a similar mechanism likely modulates osteoblastic (bone-forming) metastatic lesions as well. The development of targeted therapies either to block initial cancer cell chemotaxis, invasion and adhesion or to break the 'vicious cycle' is dependent on a more complete understanding of bone metastases. Although bisphosphonates delay progression of skeletal metastases, it is clear that more-effective therapies are needed. Cancer-associated bone morbidity remains a major public health problem, and to improve therapy and prevention it is important to understand the pathophysiology of the effects of cancer on bone. This review details scientific advances in this area.

TGF-beta and BMP7 interactions in tumour progression and bone metastasis

The skeleton is the second most frequent site of metastasis. However, only a restricted number of solid cancers, especially those of the breast and prostate, are responsible for the majority of the bone metastases. Metastatic bone disease is a major cause of morbidity, characterised by severe pain and high incidence of skeletal and haematopoietic complications (fractures, spinal cord compression and bone marrow aplasia) requiring hospitalisation. Despite the frequency of skeletal metastases, the molecular mechanisms for their propensity to colonise bone are poorly understood and treatment options are often unsatisfactory. TGF-beta and the signalling pathway it controls appears to play major roles in the pathogenesis of many carcinomas, both in their early stages, when TGF-beta acts to arrest growth of many cell types, and later in cancer progression when it contributes, paradoxically, to the phenotype of tumour invasiveness. Here we discuss some novel insights of the TGF-beta superfamily-including BMPs and their antagonists-in the formation of bone metastasis. Increasing evidence suggests that the TGF-beta superfamily is involved in bone homing, tumour dormancy, and development of micrometastases into overt bone metastases. The established role of TGF-beta/BMPs and their antagonists in epithelial plasticity during embryonic development closely resembles neoplastic processes at the primary site as well as in (bone) metastasis. For instance, the tumour-stroma interactions occurring in the tissue of cancer origin, including epithelium-to-mesenchyme transition (EMT), bear similarities with the role of bone matrix-derived TGF-beta in skeletal metastasis formation.

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.

Disruption of CXCR4 enhances osteoclastogenesis and tumor growth in bone

CXCR4 regulates hematopoietic and tumor cell homing to bone, but its role during osteoclast (OC) development is unknown. We investigated the role of CXCR4 in osteoclastogenesis and in a model of bone metastasis. Compared with controls, mice reconstituted with CXCR4 null hematopoietic cells exhibited elevated markers of bone resorption, increased OC perimeter along bone, and increased bone loss. CXCR4-/- OCs demonstrated accelerated differentiation and enhanced bone resorption in vitro. Furthermore, tumor growth specifically in bone was significantly increased in mice reconstituted with CXCR4-/- hematopoietic cells. Finally, enhancement of bone tumor growth in the absence of CXCR4 was abrogated with the OC inhibitor, zoledronic acid. These data demonstrate that disruption of CXCR4 enhances osteoclastogenesis and suggest that inhibition of CXCR4 may enhance established skeletal tumor burden by increasing OC activity.

Meta-analysis of clodronate and breast cancer survival

Clinical trials have reported conflicting results on whether oral clodronate therapy improves survival in breast cancer patients. This study was undertaken to evaluate further the effect of oral clodronate therapy on overall survival, bone metastasis-free survival and nonskeletal metastasis-free survival among breast cancer patients. An extensive literature search was undertaken for the period 1966 to July 2006 to identify clinical trials examining survival in breast cancer patients who received 2 or 3 years of oral clodronate therapy at 1600 mg day(-1) compared with those without therapy. Meta-analyses were carried out separately for patients diagnosed with advanced breast cancer and early breast cancer. Our meta-analysis found no evidence of any statistically significant difference in overall survival, bone metastasis-free survival or nonskeletal metastasis-free survival in advanced breast cancer patients receiving clodronate therapy or early breast cancer patients receiving adjuvant clodronate treatment compared with those who did not receive any active treatment.

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

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

Oral sodium clodronate for nonmetastatic prostate cancer--results of a randomized double-blind placebo-controlled trial: Medical Research Council PR04 (ISRCTN61384873)

BACKGROUND

The most frequent site of metastases from prostate cancer is bone. Adjuvant bisphosphonate treatment improves outcomes of patients with bone metastasis-negative breast cancer, but the effects of bisphosphonates on bone metastases in prostate cancer are not known.

METHODS

We performed a randomized double-blind placebo-controlled trial to determine whether a first-generation bisphosphonate could improve symptomatic bone metastasis-free survival (time to symptomatic bone metastases or death from prostate cancer) in men with nonmetastatic prostate cancer who were at high risk of developing bone metastases. Between June 1, 1994, and December 31, 1997, 508 men from 26 UK sites and one New Zealand site who were within 3 years of initial prostate cancer diagnosis with no evidence of metastases from current bone scanning were randomly assigned to daily oral sodium clodronate (2080 mg/day, n = 254) or placebo (n = 254) for a maximum of 5 years. Estimates of outcome risks were compared using Kaplan-Meier analyses.

RESULTS

The groups allocated to each treatment were well balanced. After a median follow-up of nearly 10 years, no evidence of benefit to the clodronate group was observed in terms of bone metastases-free survival (clodronate versus placebo, 80 events versus 68 events; hazard ratio [HR] = 1.22; 95% confidence interval [CI] = 0.88 to 1.68) or overall survival (clodronate versus placebo, 130 deaths versus 127 deaths; HR = 1.02; 95% CI = 0.80 to 1.30). Adverse events, notably gastrointestinal problems and increased lactate dehydrogenase levels, were more frequent in the clodronate group than in the placebo group; otherwise, clodronate was well tolerated. Modification of trial drug dose was more frequent in the clodronate group than the placebo group (HR = 1.63, 95% CI = 1.21 to 2.19).

CONCLUSION

Adjuvant sodium clodronate does not modify the natural history of nonmetastatic prostate cancer.

Adjuvant systemic therapy for operable breast cancer

Breast cancer is the leading cause of cancer death in women in England and Wales. Systemic adjuvant therapy for breast cancer reduces recurrence and mortality both in early and advanced breast cancer. This review primarily looks at the role of adjuvant systemic therapy following surgery. Chemotherapy and hormonal therapy has changed dramatically in the last few decades with the advent of newer aromatase inhibitors and newer chemotherapy drugs like taxol. Monoclonal antibodies targeted against breast cancer cells like trastuzumab are gaining ground recently in the adjuvant settings. In this article we have reviewed the recent evidences for the appropriate adjuvant therapy in operable breast cancer.

Effect of zoledronic acid on the doxycycline-induced decrease in tumour burden in a bone metastasis model of human breast cancer

Bone is one of the most frequent sites for metastasis in breast cancer patients often resulting in significant clinical morbidity and mortality. Bisphosphonates are currently the standard of care for breast cancer patients with bone metastasis. We have shown previously that doxycycline, a member of the tetracycline family of antibiotics, reduces total tumour burden in an experimental bone metastasis mouse model of human breast cancer. In this study, we combined doxycycline treatment together with zoledronic acid, the most potent bisphosphonate. Drug administration started 3 days before the injection of the MDA-MB-231 cells. When mice were administered zoledronic acid alone, the total tumour burden decreased by 43% compared to placebo treatment. Administration of a combination of zoledronic acid and doxycycline resulted in a 74% decrease in total tumour burden compared to untreated mice. In doxycycline- and zoledronate-treated mice bone formation was significantly enhanced as determined by increased numbers of osteoblasts, osteoid surface and volume, whereas a decrease in bone resorption was also observed. Doxycycline greatly reduced tumour burden and could also compensate for the increased bone resorption. The addition of zoledronate to the regimen further decreased tumour burden, caused an extensive decrease in bone-associated soft tissue tumour burden (93%), and sustained the bone volume, which could result in a smaller fracture risk. Treatment with zoledronic acid in combination with doxycycline may be very beneficial for breast cancer patients at risk for osteolytic bone metastasis.

Reduced incidence of distant metastases and lower mortality in 1072 patients with breast cancer with a history of hormone replacement therapy

OBJECTIVE

Substitution of estrogens (hormone replacement therapy [HRT]) is the most common therapy and prophylaxis of postmenopausal complaints. However, in most studies, long-term HRT has been associated with an increased risk for breast cancer, but the influence on a prognosis of breast cancer has been examined rarely.

STUDY DESIGN

For further investigation, we analyzed 1072 patients aged 45-70 years at the time of first diagnosis of breast cancer with and without preoperative HRT with regard to the incidence of distant metastases and overall survival. Of these, 279 women were premenopausal (mean, 47.8 +/- 3.2 years); 793 women were postmenopausal (mean, 54.5 +/- 3.5 years); 320 women had received HRT over a minimum of 1 year (mean, 5.5 +/- 4.0 years; group HRT+); and 473 women had not received HRT (group HRT-). The median follow-up time was 73.2 months.

RESULTS

Although body mass index, tumor size, and grading of group HRT- were significantly higher than in group HRT+, nodal status, S-phase fraction, hormone-receptor status, and local recurrence showed no significant differences. In regard to the incidence of distant metastases, women without HRT have significantly (P < .001) more metastases to bone (68 vs 20 women), lung (47:13 women), and liver (47:13 women). Overall survival was significantly lower in the HRT- group.

CONCLUSION

We were able to show that the use of HRT before the diagnosis of breast cancer results in more favorable primary tumors, with a lower incidence of recurrences and a better overall survival rate. This might be due to normalized bone metabolism by the use of HRT, which may lower the conditions of tumor cell seeding.

The role of bisphosphonates in early breast cancer

Clinical trials are investigating the use of bisphosphonates in patients with early (nonmetastatic) breast cancer. Results from trials of clodronate are generally encouraging but somewhat contradictory. Of the three trials published to date, two reported that clodronate had beneficial effects on both bone metastases and survival. In contrast, the third trial reported that clodronate had no effect on metastases and a negative effect on survival. Small studies of adjuvant pamidronate and zoledronic acid also produced promising data, but these need to be reproduced in a large-scale, randomized trial setting before clinically meaningful conclusions can be drawn. A number of adjuvant trials are in progress to further evaluate the role of oral clodronate and i.v. zoledronic acid and to examine the effects of the newer bisphosphonate, ibandronate (oral formulation), in this setting. One of these trials is the joint Southwest Oncology Group/Intergroup/National Surgical Adjuvant Breast and Bowel Project trial, which is designed to compare the efficacy and safety of all three of these bisphosphonates in approximately 6,000 women with early breast cancer. Patient preference for oral or i.v. therapy will also be assessed.

[Bisphosphonates in oncology]

Since bone metastases occur as a result of hematogenous spreading of tumor cells, therapy with curative intent is no longer feasible and palliative options for treating and preventing skeletal events are essential. Today, bisphosphonates are established in the systemic treatment of bone metastases. This report provides an overview of molecular mechanisms of action and clinical data of bisphosphonates in patients with skeletal metastases of breast and prostate cancer as the most common solid tumors which spread to the bone.

Preventative ibandronate treatment has the most beneficial effect on the microstructure of bone in experimental tumor osteolysis

We investigated the effect of ibandronate on three-dimensional (3-D) microstructure and bone mass in experimentally induced tumor osteolysis. Walker carcinosarcoma cells were implanted into the left femur of female rats that received 26-day ibandronate pretreatment followed by continued therapy or ibandronate posttreatment only. A tumor-only group received isotonic saline. At endpoint, excised femurs were scanned using microcomputed tomography (microCT) to assess bone volume density, bone mineral content, trabecular number/thickness, and separation for cortical plus trabecular bone or trabecular bone alone. Compared with the nonimplanted right femur, bone volume and surface density and trabecular number and thickness were reduced in the distal left femur following tumor cell implantation. microCT analysis revealed greater cortical and trabecular bone mineral content in the preventative and interventional (pre-post tumor) ibandronate group, and the interventional (post-tumor) ibandronate group, versus the tumor-only group. Bone volume density was significantly higher in pre-post and post-tumor groups compared to the tumor-only group. After preventative and interventional ibandronate, bone volume density and trabecular thickness were 13% and 60% greater, respectively, than in the post-tumor treatment group. 3-D microCT images confirmed microstructural changes. We conclude that combined interventional and preventative ibandronate preserves bone strength and integrity more than intervention alone.

Effect of a V-ATPase inhibitor, FR202126, in syngeneic mouse model of experimental bone metastasis

PURPOSE

It has been demonstrated that vacuolar ATPase (V-ATPase) is involved in various aspects of bone metastasis. The aim of this study is to investigate the effect of the anti-bone resorptive activity of the V-ATPase inhibitor FR202126 on bone metastases in mice with metastatic breast cancer.

METHOD

As a spontaneous model of breast cancer metastasis to bone, mouse breast cancer cells, 4T1, were injected into the mammary fat pad in immunocompetent syngeneic mice. The mice were orally treated with FR202126 for 29 days. Tumor volume was measured once a week. Thirty days after the injection of the cells, the bone mineral density (BMD) of the proximal tibia was measured using peripheral quantitative computed tomography. Histomorphometric analysis of the distal femurs and the proximal tibiae was performed. To elucidate the mechanism behind the anti-osteolytic effect of FR202126, 4T1 cells were treated directly in vitro with FR202126. Cell viability was measured, and cell invasion was assessed using matrigel.

RESULTS

Oral administration of FR202126 significantly increased BMD by reducing the eroded bone surface ratio. While FR202126 is known to potently inhibit osteoclast mediated bone resorption, it did not prevent invasion by cancer cells or their proliferation.

CONCLUSION

The V-ATPase inhibitor FR202126 was found to be effective at ameliorating osteolysis induced by metastatic breast cancer, even when the cancer cells themselves are not significantly affected by it. These results suggest that the anti-bone resorptive effect of the V-ATPase inhibitor might be useful for treating bone metastases associated with breast cancer.

Differential effects of Ca(2+) on bisphosphonate-induced growth inhibition in breast cancer and mesothelioma cells

Bisphosphonates are widely clinically used inhibitors of bone resorption. Pre-clinical studies indicate that bisphosphonates also inhibit the growth of various cancer cells in vitro, but their in vivo anti-cancer activity varies greatly, depending on the tumor type. We compared the various cellular effects of bisphosphonates in breast cancer and mesothelioma cells, with differences in growth inhibition responses to bisphosphonate-treatment in vivo. We show that the growth inhibitory effects of nitrogen-containing bisphosphonates are significantly affected by excess Ca(2+) in a cell- and bisphosphonate-specific fashion. Furthermore, excess pyrophosphate-resembling bisphosphonates prevent nitrogen-containing-bisphosphonate-induced accumulation of unprenylated Rap1A, p38 phosphorylation and growth inhibition in human MDA-MB-231 breast cancer and mouse AB-12 mesothelioma cells. For some, but not all tested, pyrophosphate-resembling bisphosphonate: nitrogen-containing bisphosphonate combinations these results may be partially explained by the ability of the excess pyrophosphate-resembling bisphosphonates to chelate Ca(2+). In mice, subcutaneous AB-12 and MDA-MB-231 tumors exhibit positive staining for Ca(2+) minerals, as revealed with Von Kossa stainings. We further show that the AB-12 tumors accumulate significantly more of the bone scanning bisphosphonate, Tc99m-medronate, as compared with MDA-MB-231 tumors. In conclusion, our results suggest that Ca(2+) regulates the growth inhibitory effects of bisphosphonates in a target cell and drug-specific fashion. These findings may be of physiological relevance since many tumor types are calcified. They further suggest that bisphosphonates can accumulate in tumors that are growing at the visceral sites and that differences in tumor accumulation of bisphosphonates may regulate their in vivo sensitivity to these drugs.

Combined therapy of Sr-89 and zoledronic acid in patients with painful bone metastases

PURPOSE

We evaluated the pain response and daily discomfort in patients with painful bone metastases treated by merging 89Sr-chloride and zoledronic acid. The results were compared with those of patients who received 89Sr-chloride or zoledronic acid separately.

METHODS

25 patients (12 women; mean age 65+/-13 years) chronically treated with zoledronic acid underwent bone pain palliation with 150 MBq of 89Sr-chloride at least 6 months later that bisphoshonate therapy started (group A). 13 patients (6 women; mean age 70+/-12 years) received 89Sr-chloride alone (group B) and 11 patients (5 women; mean age 69+/-12 years) were chronically treated and continued to receive only zoledronic acid therapy (group C), both constituted the control groups. Patients kept a daily pain diary assessing both their discomfort and the pain of specific sites by using a visual analog scale (VAS), rating from 0 (no d iscomfort-no pain) to 10 (worst discomfort-pain). These diaries were reviewed weekly for 2 months and three different physicians rated the pain response on a scale of -2 (considerable deterioration) to +2 (considerable improvement).

RESULTS

Baseline characteristics were similar in the three groups. The reduction of total discomfort and of bone pain in the group A was significantly greater as compared to group B (P<0.01) and group C (P<0.01). During the monitored period, a significant improvement of clinical conditions was observed in the group A, varying the rate from -1 to 1 as compared to both groups B and C in which the rate changed from -1 to 0.

CONCLUSION

Our findings indicate that combined therapy of 89Sr-chloride and zoledronic acid in patients with painful bone metastases is more effective in treating pain and improving clinical conditions than 89Sr-chloride or zoledronic acid used separately.

Mechanisms of disease: Preclinical reports of antineoplastic synergistic action of bisphosphonates

For patients with malignant bone disease, bisphosphonate therapy is the standard treatment. Preclinical and preliminary clinical data suggest that bisphosphonates have direct or indirect antitumor effects: they affect growth-factor release, cancer-cell adhesion, invasion and viability, angiogenesis, and apoptosis of cancer cells. These effects might be enhanced through co-administration with chemotherapy agents, biological agents, or both. We survey the biochemical pathways and molecular targets of bisphosphonates, and discuss the molecular mechanisms of these antitumor effects, as well as the documented antineoplastic preclinical effects of bisphosphonates used in combination with cytotoxic and biological drugs. Moreover, the positive interactions between bisphosphonates and farnesyltransferase inhibitors, KIT receptor tyrosine kinase inhibitors (e.g. imatinib mesylate) and cyclo-oxygenase-2 inhibitors are discussed in relation to their potential synergistic and additive effects. We briefly discuss identification of new molecular targets of bisphosphonates from genomic and proteomic analysis, and highlight the cellular consequences of drug-related enzyme inhibition.