Rationale for zoledronic acid therapy in men with hormone-sensitive prostate cancer with or without bone metastasis

Bone-targeting agents in major solid tumour metastases: a multinational cohort study

OBJECTIVE

To describe the epidemiology, clinical characteristics and utilisation patterns of bone-targeting agents (BTAs) in patients with bone metastases from breast, prostate and lung cancer.

METHODS

This is a multinational retrospective cohort study including patients with three major solid tumours (breast, prostate and lung cancer) and newly initiated on BTAs (ie, denosumab, zoledronic acid and pamidronate). Records were retrieved from nationwide health databases from Hong Kong and Taiwan (HK and TW: 2013-2017) and Korea (KR: 2012-2016). Descriptive analyses included the annual incidence rates of bone metastases and the cumulative incidence curves of BTA initiation. We used Sankey diagrams to visualise the dynamic BTA utilisation patterns.

RESULTS

The annual incidence rate of bone metastases ranged from 3.5% to 4.5% in TW, from 9.6% to 10.3% in HK and from 2.9% to 3.8% in KR. We identified 14.1% (5127), 9.3% (883) and 9.4% (4800) of patients with bone metastases newly initiated on BTAs in TW, HK and KR, respectively. The most frequently used BTA in TW (67.1%) and HK (51.9%) was denosumab, while in KR (84.8%) it was zoledronic acid. Sankey diagrams indicated the proportion of patients remaining on denosumab was highest in TW and HK, while it was zoledronic acid in KR. Specifically, in TW, patients who were on bisphosphonates or had discontinued treatment frequently switched to or reinitiated denosumab.

CONCLUSIONS

We found the rate of BTA utilisation remained low across all sites and tumour types in recent years. The dynamic utilisation patterns of BTAs provide better understanding of the treatment landscape for future evaluation of associated outcomes of patients.

Molecular predictors of metastasis in patients with prostate cancer

INTRODUCTION

Prostate cancer is a serious threat to the health of older adults worldwide. The quality of life and survival time of patients sharply decline once metastasis occurs. Thus, early screening for prostate cancer is very advanced in developed countries. The detection methods used include Prostate-specific antigen (PSA) detection and digital rectal examination. However, the lack of universal access to early screening in some developing countries has resulted in an increased number of patients presenting with metastatic prostate cancer. In addition, the treatment methods for metastatic and localized prostate cancer are considerably different. In many patients, early-stage prostate cancer cells often metastasize due to delayed observation, negative PSA results, and delay in treatment time. Therefore, the identification of patients who are prone to metastasis is important for future clinical studies.

AREAS COVERED

this review introduced a large number of predictive molecules related to prostate cancer metastasis. These molecules involve the mutation and regulation of tumor cell genes, changes in the tumor microenvironment, and the liquid biopsy.

EXPERT OPINION

In next decade, PSMA PET/CT and liquid biopsy will be the excellent predicting tools, while ¹⁷⁷ Lu- PSMA-RLT will be showed excellent anti-tumor efficacy in mPCa patients.

Genome-Based Classification and Therapy of Prostate Cancer

In the past decade, multi-national and multi-center efforts were launched to sequence prostate cancer genomes, transcriptomes, and epigenomes with the aim of discovering the molecular underpinnings of tumorigenesis, cancer progression, and therapy resistance. Multiple biological markers and pathways have been discovered to be tumor drivers, and a molecular classification of prostate cancer is emerging. Here, we highlight crucial findings of these genome-sequencing projects in localized and advanced disease. We recapitulate the utility and limitations of current clinical practices to diagnosis, prognosis, and therapy, and we provide examples of insights generated by the molecular profiling of tumors. Novel treatment concepts based on these molecular alterations are currently being addressed in clinical trials and will lead to an enhanced implementation of precision medicine strategies.

Healthcare-resource utilization associated with radiation to bone across eight European countries: Results from a retrospective study

Background

Bone metastases and lytic lesions due to multiple myeloma are common in advanced cancer and can lead to debilitating complications (skeletal-related events [SREs]), including requirement for radiation to bone. Despite the high frequency of radiation to bone in patients with metastatic bone disease, our knowledge of associated healthcare resource utilization (HRU) is limited.

Methods

This retrospective study estimated HRU following radiation to bone in Austria, the Czech Republic, Finland, Greece, Poland, Portugal, Sweden and Switzerland. Eligible patients were ≥ 20 years old, had bone metastases secondary to breast, lung or prostate cancer, or bone lesions associated with multiple myeloma, and had received radiation to bone between 1 July 2004 and 1 July 2009. HRU data were extracted from hospital patient charts from 3.5 months before the index SRE (radiation to bone preceded by a SRE-free period of ≥ 6.5 months) until 3 months after the last SRE that the patient experienced during the study period.

Results

In total, 482 patients were included. The number of inpatient stays increased from baseline by a mean of 0.52 (standard deviation [SD] 1.17) stays per radiation to bone event and the duration of stays increased by a mean of 7.8 (SD 14.8) days. Outpatient visits increased by a mean of 4.24 (SD 6.57) visits and procedures by a mean of 8.51 (SD 7.46) procedures.

Conclusion

HRU increased following radiation to bone across all countries studied. Agents that prevent severe pain and delay the need for radiation have the potential to reduce the burden imposed on healthcare resources and patients.

Exploiting machine learning for predicting skeletal-related events in cancer patients with bone metastases

The aim of the bone metastases (BM) treatment is to prevent the occurrence of skeletal-related events (SREs). In clinical, physicians could only predict the occurrence of SREs by subjective experience. Machine learning (ML) could be used as predictive models in the medical field. But there is no published research using ML to predict SREs in cancer patients with BM. The purpose of this study was to assess the associations of clinical variables with the occurrence of SREs and to subsequently develop prediction models to help identify SREs risk groups.

We analyzed 1143 cancer patients with BM. We used the statistical package of SPSS and SPSS Modeler for data analysis and the development of the prediction model. We compared the performance of logistic regression (LR), decision tree (DT) and support vector machine(SVM). The results suggested that Visual Analog Scale (VAS) scale was a key factor to SREs in LR, DT and SVM model. Modifiable factors such as Frankel classification, Mirels score, Ca, aminoterminal propeptide of type I collagen (PINP) and bone-specific alkaline phosphatase (BALP) were identified. We found that the result of applying LR, DT and SVM classification accuracy was 79.2%, 85.8% and 88.2%, with 9, 4 and 8 variables, respectively.

In conclusion, DT and SVM achieved higher accuracies with smaller number of variables than the number of variables used in LR. ML techniques can be used to build model to predict SREs in cancer patients with BM.

Longitudinal patterns of bone-targeted agent use among patients with solid tumors and bone metastases in the United States

Purpose

This study examined real-world long-term use of guideline-recommended bone targeted agents (BTA) among patients with metastatic solid tumors.

Methods

Adults with a solid tumor diagnosis followed by a bone metastasis diagnosis in 2012–2014 were identified from electronic medical records in the Oncology Services Comprehensive Electronic Records (OSCER) database. Patients initiated zoledronic acid (ZA) or denosumab on or after the bone metastasis diagnosis and were followed through last clinic visit by 30 June 2015. We describe time to BTA initiation, compliance (≥12 administrations in a year), switching, and non-persistence (switch or ≥90 day gap in therapy), by agent and follow-up period.

Results

The majority of the 14,881 study patients (50% female, 65% age ≥65 years) had breast (33%), prostate (26%), or lung (26%) tumors. Half of all patients initiated on each agent, with denosumab initiations exceeding ZA initiations in 2014. Most (91% denosumab, 93% ZA) initiations occurred within 3 months of bone metastasis diagnosis. At 1, 2, and 3 years post-initiation, denosumab patients were less likely to switch agents (4, 3, and 1% versus 14, 12, and 11%) and more likely to be compliant (50, 37, and 31% versus 41, 26, and 6%). Median time to non-persistence was 25.9 months for denosumab and 17.2 months for ZA, p < 0.0001.

Conclusions

This is the first study reporting long-term treatment patterns for the two primary BTAs used in the USA. The greater compliance and longer persistence observed among denosumab patients may improve treatment effectiveness achieved in the real-world setting.

Electronic supplementary material

The online version of this article (doi:10.1007/s00520-017-3583-1) contains supplementary material, which is available to authorized users.

Hypercalcaemia and hypocalcaemia: finding the balance

Calcium metabolism in cancer and hypercalcaemia of malignancy

The balance between bone formation and resorption may be disrupted in patients with cancer, leading either to increased bone resorption, calcium release, and possibly hypercalcaemia, or to increased bone formation, sequestration of calcium, and possibly hypocalcaemia. In adults, hypercalcaemia of malignancy is most common in patients with tumours that produce factors that induce osteoclast activation and enhance bone resorption. Impaired renal function and increased renal tubular calcium resorption may further affect calcium levels.

Treatment of hypercalcaemia of malignancy

Inhibitors of bone resorption, first the bisphosphonates and, later, denosumab, have been shown to be effective in hypercalcaemia treatment. Bisphosphonates (which are administered intravenously) are approved for hypercalcaemia of malignancy and are the current mainstay of treatment, whereas denosumab (which is administered subcutaneously) may offer an option for patients who do not respond to bisphosphonates or suffer from renal insufficiency.

Hypocalcaemia: treatment and prevention

Hypocalcaemia is most common in patients with prostate cancer and osteoblastic bone metastases, but can occur in patients with a variety of tumour types who are receiving inhibitors of bone resorption. While patients often respond to calcium and vitamin D supplementation, prevention should be the aim; at-risk patients should be identified before starting treatment with inhibitors of bone resorption, be closely monitored during at least the first few months of treatment, and receive concomitant calcium and vitamin D supplementation unless hypercalcaemia is present.

Conclusion

Both hypercalcaemia and hypocalcaemia can be serious if left untreated. It is therefore important that patients with cancer are closely monitored and receive adequate prevention and treatment measures to maintain normal blood calcium levels.

Diagnostic imaging to detect and evaluate response to therapy in bone metastases from prostate cancer: current modalities and new horizons

Different therapeutic options for the management of prostate cancer (PC) have been developed, and some are successful in providing crucial improvement in both survival and quality of life, especially in patients with metastatic castration-resistant PC. In this scenario, diverse combinations of radiopharmaceuticals (for targeting bone, cancer cells and receptors) and nuclear medicine modalities (e.g. bone scan, SPECT, SPECT/CT, PET and PET/CT) are now available for imaging bone metastases. Some radiopharmaceuticals are approved, currently available and used in the routine clinical setting, while others are not registered and are still under evaluation, and should therefore be considered experimental. On the other hand, radiologists have other tools, in addition to CT, that can better visualize bone localization and medullary involvement, such as multimodal MRI. In this review, the authors provide an overview of current management of advanced PC and discuss the choice of diagnostic modality for the detection of metastatic skeletal lesions in different phases of the disease. In addition to detection of bone metastases, the evaluation of response to therapy is another critical issue, since it remains one of the most important open questions that a multidisciplinary team faces when optimizing the management of PC. The authors emphasize the role of nuclear modalities that can presently be used in clinical practice, and also look at future perspectives based on relevant clinical data with novel radiopharmaceuticals.

The biology and clinical implications of prostate cancer dormancy and metastasis

Disseminated tumor cells (DTCs) are detected early in the disease process in prostate cancer (PCa) patients and can persist after radical prostatectomy. DTCs can remain dormant in patients with no evidence of disease for a prolonged period of time only to recur 10 or more years later. Recent advances in single-cell genomics and transcriptomics have provided much needed insight into DTC biology and cancer dormancy in patients. With the development of new in vitro and preclinical models, researchers recapitulate the clinical events in patients and therefore allow further elucidation of the molecular mechanisms underlying cancer dormancy and escape. In this review, we explore novel ideas on the detection, heterogeneous transcriptomic profiles, molecular and cellular mechanisms of dormancy, and potential mechanisms underlying dormancy escape by DTCs. As such, there is hope that identifying and targeting novel dormancy-associated pathways in patients with residual disease will have significant clinical implications for the treatment of PCa patients in the future.

Systematic literature review and network meta-analysis comparing bone-targeted agents for the prevention of skeletal-related events in cancer patients with bone metastasis

BACKGROUND

Complications from skeletal-related events (SREs) constitute a challenge in the care of cancer patients with bone metastasis (BM).

OBJECTIVES

This study evaluated the comparative effectiveness of pamidronate, ibandronate, zoledronate, and denosumab in reducing the morbidity of SREs in cancer patients with BM.

METHODS

Medline (1948 to January 2014), Embase (1980 to January 2014), the Cochrane Library (2014 issue 1), and Web of Science with Conference Proceedings (1970 to January 2014) were searched. Only randomized controlled trials assessing denosumab, bisphosphonates, or placebo in cancer patients with BM were included. The primary outcomes were SREs and SREs by type. The network meta-analysis (NMA) was performed with a random-effects Bayesian model.

RESULTS

The NMA included 14 trials with 10,192 patients. Denosumab was superior to placebo in reducing the risk of SREs (odds ratio [OR]: 0.49; 95% confidence interval [CI]: 0.31-0.75), followed by zoledronate (OR: 0.57; 95% CI: 0.41-0.77) and pamidronate (OR: 0.55; 95% CI: 0.41-0.72). Ibandronate compared with placebo could not reduce the risk of SREs. Denosumab was superior to placebo in reducing the risk of pathologic fractures (OR: 0.50; 95% CI: 0.32-0.79), followed by zoledronate (OR: 0.61; 95% CI: 0.43-0.86). Denosumab was superior to placebo in reducing the risk of radiation (OR: 0.51; 95% CI: 0.35-0.75), followed by pamidronate (OR: 0.67; 95% CI: 0.52-0.86) and zoledronate (OR: 0.70; 95% CI: 0.52-0.96).

CONCLUSION

This NMA showed that denosumab, zoledronate, and pamidronate were generally effective in preventing SREs in cancer patients with BM. Denosumab and zoledronate were also associated with reductions in the risk of pathologic fractures and radiation compared with placebo. Denosumab was shown to be the most effective of the bone-targeted agents.

The role of the microenvironment-dormant prostate disseminated tumor cells in the bone marrow

Disseminated tumor cells (DTC) leave the primary tumor and reside in distant sites (e.g. bone) early in prostate cancer. Patients may harbor dormant DTC which develop into clinically overt metastasis years after radical prostatectomy. We will describe recent evidence suggesting high p38/ERK ratio, bone morphogenetic proteins, and tumor growth factor-beta 2 promote dormancy in solid tumors. Furthermore, we will discuss the possible regulation of dormancy by hematopoietic stem cell and vascular niches, and describe novel models recapitulating bone marrow metastatic latency and out- growth, 3D microvascular networks, and 3D biomatrix supportive niches in the studies of tumor cell dormancy.

Health Resource Utilization Associated with Skeletal-Related Events in Patients with Advanced Prostate Cancer: A European Subgroup Analysis from an Observational, Multinational Study

This study aimed to increase the understanding of health resource utilization (HRU) associated with skeletal-related events (SREs) occurring in patients with bone metastases secondary to advanced prostate cancer. A total of 120 patients from Germany, Italy, Spain and the United Kingdom were enrolled in this observational study. They had bone metastases secondary to prostate cancer and had experienced at least one SRE in the 97 days before giving informed consent. HRU data were collected retrospectively for 97 days before enrolment and prospectively for up to 18–21 months. HRU, including the number and duration of inpatient hospitalizations, number of outpatient and emergency department visits and procedures, was independently attributed by investigators to an SRE. Of the 222 SREs included in this analysis, 26% were associated with inpatient stays and the mean duration per SRE was 21.4 days (standard deviation (SD) 17.8 days). Overall, 174 SREs (78%) required an outpatient visit and the mean number of visits per SRE was 4.6 (SD 4.6). All SREs are associated with substantial HRU. Preventing SREs in patients with advanced prostate cancer and bone metastases may help to reduce the burden to both patients and European healthcare systems.

Patients with bone metastases from solid tumors initiating treatment with a bone-targeted agent in 2011: a descriptive analysis using oncology clinic data in the US

PURPOSE

Three bone-targeted agents (BTAs) are approved in the USA for prevention of bone complications among solid tumor patients with bone metastases: two intravenous bisphosphonates (IV BP) (pamidronate and zoledronic acid), and one subcutaneous receptor activator of nuclear factor-kappaB (RANK) ligand inhibitor (denosumab). Using electronic medical record data from outpatient community and hospital-affiliated oncology clinics, we examined the characteristics of patients who initiated treatment with a BTA in 2011 and followed them for a maximum of 12 months.

METHODS

Adult patients with bone metastasis secondary to solid tumors newly treated with a BTA during 2011 were identified from the Oncology Services Comprehensive Electronic Records (OSCER) database. We examined patient characteristics at BTA initiation, treatment patterns, and compliance during a 12-month period. Sensitivity analyses were performed in a subgroup of patients who had confirmed 12 months of follow-up data.

RESULTS

Denosumab patients (N = 1,594) were older (65 % ≥65 years vs. 60 % ≥65 years), further along in their disease progression (time since bone metastasis diagnosis: 16 % ≥2 years vs. 10 % ≥2 years), less likely to switch BTA (overall: 6 vs. 14 %; subgroup: 8 vs. 19 %), and more compliant with treatment (overall: median doses of 7 vs. 4; subgroup: 11 vs. 8) compared to IV BP patients (N = 1,975). Findings were consistent across gender, age, tumor type, naïve, and transition strata.

CONCLUSIONS

Patients receiving denosumab and IV BPs may differ. Despite higher age and more advanced disease, patients treated with denosumab are more likely to stay on treatment and have better compliance.

Thermotherapy using magnetic cationic liposomes powerfully suppresses prostate cancer bone metastasis in a novel rat model

BACKGROUND

Bone metastasis is a serious problem for individuals with prostate cancer, and the effects of the anticancer drug docetaxel (DTX) are insufficient. We therefore examined the therapeutic potential of magnetic cationic liposomes (MCL) in a novel rat model that allows the evaluation of tumor immunity. The effects of MCL thermotherapy were compared with those of DTX as a conventional therapy for the treatment of bone metastatic prostate cancer.

METHODS

Prostate tumor tissues were transplanted into the femurs of model rats divided into four groups: control, MCL, DTX, and MCL + DTX. Tumors were injected with MCL, and alternating magnetic field (AMF) irradiation was performed three times a week. Tumor proliferation and bone destruction were evaluated by proliferating cell nuclear antigen positivity, computed tomography, and CD68-positive cell number, while tumor immunity was evaluated by heat shock protein (HSP) 70 expression and CD8-positive lymphocyte number.

RESULTS

We successfully established a novel femur metastasis model of prostate cancer, and demonstrated that tumor proliferation and bone destruction in the MCL and MCL + DTX groups were significantly suppressed compared with control and DTX groups. MCL thermotherapy concurrently induced necrosis and apoptosis. The expression of HSP70 in the MCL and MCL + DTX groups was also significantly increased, and tumor immunity was enhanced through the induction of CD8-positive lymphocytes.

CONCLUSION

MCL thermotherapy was clearly more effective than DTX in treating bone metastatic prostate cancer. A combination of MCL thermotherapy and DTX therefore deserves consideration as a novel treatment for this disease.

Cost of skeletal-related events in European patients with solid tumours and bone metastases: data from a prospective multinational observational study

OBJECTIVES

Patients with bone metastases often experience skeletal-related events (SREs: radiation or surgery to bone, pathologic fracture, and spinal cord compression). This study examined health resource utilization and costs associated with SREs.

METHODS

Data presented are from the European cohort (Germany, Italy, Spain, and the UK) of patients with solid tumours enrolled in a multi-national, prospective, observational study in patients with solid tumours or multiple myeloma. Patients with Eastern Cooperative Oncology Group score 0-2 and life expectancy ≥6 months, who experienced an SRE up to 97 days before enrolment, were eligible. Health resource utilization associated with SREs (including number/length of inpatient stays, numbers of procedures and outpatient visits) were collected through chart review for up to 97 days before enrolment and prospectively during follow-up. Country-specific cost calculations were performed.

RESULTS

In total, 478 eligible patients contributed 893 SREs to this analysis. Radiation to bone occurred most frequently (66% of total). Spinal cord compression (7%) and surgery to bone (10%) were the least common events, but most likely to require inpatient stays. The most costly SREs were also spinal cord compression (mean per SRE across countries, €4884-€12,082) and surgery to bone (€3348-€9407). Inpatient stays were the main cost drivers.

LIMITATIONS

Health resource utilization used to calculate the costs associated with SREs may have been under-estimated as a result of exclusion of patients with low performance status or life expectancy; unavailable information and exclusion of resource consumption associated with pain. Thus, the estimate of associated costs is likely to be conservative.

CONCLUSIONS

SREs result in considerable health resource utilization, imposing a substantial financial burden driven by inpatient stays. Treatments that prevent/delay SREs may help ease this burden, thereby providing cost savings across European healthcare systems.

Preserving bone health in patients with hormone-sensitive prostate cancer: the role of bisphosphonates

Men with prostate cancer initiating androgen-deprivation therapy (ADT) may have multiple factors that threaten their skeletal health, including increased fracture risk from bone loss during ADT and the propensity to develop bone metastases, which may lead to skeletal-related events (SREs). Bisphosphonates have utility in oncology for patients with bone metastases to prevent bone loss during hormonal therapy and in the benign setting to treat osteoporosis. These agents have an emerging role in patients with hormone-sensitive prostate cancer (HSPC). Etidronate, alendronate, pamidronate, and zoledronic acid have all shown efficacy in preventing ADT-related bone loss. Alendronate and zoledronic acid have also been shown to increase bone mineral density vs baseline during ADT. Patients with bone metastases from HSPC who received 4 mg zoledronic acid every 3 or 4 weeks had a low incidence of skeletal complications, although controlled study data have not been reported. Bisphosphonate treatment in men with HSPC may be effective for the prevention of ADT-related bone loss, underscoring the importance of treating early to avoid SREs and potentially delay disease progression to metastatic bone disease.

Osteonecrosis of the jaw in prostate cancer patients with bone metastases treated with zoledronate: a retrospective analysis

Osteonecrosis of the jaw (ONJ) has recently been reported as a potentially serious complication of prolonged treatment with intravenous bisphosphonates. We studied its frequency in prostate cancer patients receiving intravenous zoledronate. The medical and dental records of 52 consecutive patients with prostate cancer and bone metastases treated at our institute between January 2002 and October 2005 were reviewed. All patients received intravenous zoledronate 4 mg every 3 or 4 weeks and concomitant conventional prostate cancer treatments. We analysed the association of ONJ with the number of administrations of zoledronate and exposure to chemotherapy. At a median follow-up of 7 months (range 1-41) after the initiation of zoledronate, ONJ occurred in six patients (12%, 95% C.I. 5.4-23.0%). All six ONJ cases occurred after the 9(th) administration of zoledronate. The median number of zoledronate administrations was 17 (range 9-24) and 8 (range 1-32) for patient developing and not developing ONJ, respectively (p =0.02). Chemotherapy with docetaxel was also associated with a strong, but not statistically significant, trend towards increased risk of ONJ (OR 3.8, 95% C.I. 0.4-35.6, p =0.24). The length of exposure to zoledronate was associated with an increased frequency of ONJ in prostate cancer patients. A possible role of chemotherapy with docetaxel as a cofactor for ONJ merits further evaluation.

Zoledronic acid increases docetaxel cytotoxicity through pMEK and Mcl-1 inhibition in a hormone-sensitive prostate carcinoma cell line

Background

In prostate cancer, the identification of drug combinations that could reduce the tumor cell population and rapidly eradicate hormone-resistant cells potentially present would be a remarkable breakthrough in the treatment of this disease.

Methods

The study was performed on a hormone-sensitive prostate cancer cell line (LNCaP) grown in normal or hormone-deprived charcoal-stripped (c.s.) medium. Cell viability and apoptosis were assessed by SRB assay and Annexin-V/TUNEL assays, respectively. Activated caspase-3, p21, pMEK and MCL-1 expression levels were detected by western blotting.

Results

The simultaneous exposure of zoledronic acid [100 μM] and docetaxel [0.01 μM] for 1 h followed by treatment with zoledronic acid for 72, 96 or 120 h produced a high synergistic interaction (R index = 5.1) with a strong decrease in cell viability. This cytotoxic effect was associated with a high induction of apoptosis in both LNCaP and in c.s. LNCaP cells. The induction of apoptosis was paralleled by a decrease in pMEK and Mcl-1 expression.

Conclusion

The zoledronic acid-docetaxel combination produced a highly significant synergistic effect on the LNCaP cell line grown in normal or hormone-deprived medium, the principal molecular mechanisms involved being apoptosis and decreased pMEK and Mcl-1 expression. This experimentally derived schedule would seem to prevent the selection and amplification of hormone-resistant cell clones and could thus be potentially used alongside standard androgen deprivation therapy in the management of hormone-sensitive prostate carcinoma.

RANKL inhibition is an effective adjuvant for docetaxel in a prostate cancer bone metastases model

BACKGROUND

Docetaxel induces an anti-tumor response in men with advanced prostate cancer (PCa); however, the side effects associated with docetaxel treatment can be severe, resulting in discontinuation of therapy. Thus, identification of an effective adjuvant therapy to allow lower doses of docetaxel is needed. Advanced PCa is typically accompanied by skeletal metastasis. Receptor activator of NFkB ligand (RANKL) is a key pro-osteoclastic factor. Targeting RANKL decreases establishment and progression of PCa growth in bone in murine models.

METHODS

The efficacy of inhibiting RANKL, using a recombinant soluble RANK extracellular domain fused with the immunoglobulin Fc domain (RANK-Fc), was tested as an adjuvant therapy with docetaxel for PCa bone metastasis in a murine intra-tibial model.

RESULT

The combination of RANK-Fc and docetaxel reduced tumor burden in bone greater than either treatment alone.

CONCLUSION

The combination of docetaxel with a RANKL-inhibiting agent merits further investigation for treatment of advance PCa.

Effect of heat therapy using magnetic nanoparticles conjugated with cationic liposomes on prostate tumor in bone

BACKGROUND

We have developed magnetite nanoparticles conjugated with cationic liposomes (MCLs) to induce intracellular hyperthermia with exposure to an alternating magnetic field (AMF). We have previously demonstrated the hyperthermic effect of MCLs against certain types of malignant tumor cells in vivo. Here, we examine the effects of MCL + AMF heat therapy on prostate cancer tissue in a bone microenvironment and on bone destruction in a rat model.

MATERIALS AND METHODS

Rat prostate cancer nodules were transplanted onto the calvaria of 6-week-old F344 male rats. MCLs were injected into the tumor which reached 7 mm in diameter, and then the animals were exposed to repeated AMF irradiation. The distribution of MCL, tumor necrosis, cell proliferation, and bone destruction in the bone microenvironment were evaluated.

RESULTS

MCL + AMF heat therapy suppressed tumor growth on the calvaria, and histologically, the induction of a necrotic mass was observed around magnetic particles in the tumor. The bone destruction index, which indicates the degree of osteolysis associated with prostate tumor growth in the bone microenvironment, was 34.8% in the MCL group and 67.2% in the control group with significant difference. However, almost half of rats were dead in this experiment.

CONCLUSION

MCL + AMF heat therapy suppressed tumor proliferation in the bone microenvironment, in addition to bone destruction. However, this method may exhibit side effects for central nerve system. If MCL are specifically taken into the prostate cancer cells in the bone microenvironment, this method may be useful for the treatment of bone metastatic lesions of prostate cancer.

The effects on hTERT gene expression is an additional mechanism of amino-bisphosphonates in prostatic cancer cells

Many studies have demonstrated various effects of bisphosphonates on several cancer cells and it is accepted that their anti-tumor activity is related to interference with the mevalonate pathway. In addition, it is well known that gene expression of hTERT, the catalytic subunit of the telomerase, is elevated in prostatic cancer. In the prostate cancer cell lines we investigated the effects on hTERT gene expression of several bisphosphonates. We also evaluated whether the observed levels of expression were affected by the exposure to an analogue of the geranylgeranylpyrophosphate, the geranylgeraniol used to recover the mevalonate pathway. Our results showed that the amino-bisphosphonates down-regulate hTERT gene expression and that combined treatment with geranylgeraniol and zoledronate was able to revert only partially the effects on viability; on the contrary, hTERT gene down-regulation was not affected by the restoration of the mevalonate pathway. These results support the hypothesis that prostatic cancer cells are targeted by amino-bisphosphonates also through a different mechanism from the mevalonate pathway.