Clodronate for treatment of bone metastases in hormone refractory prostate cancer

Assessment of anticancer-treatment outcome in patients with metastatic castration-resistant prostate cancer-going beyond PSA and imaging, a systematic literature review

BACKGROUND

In the past years, there has been significant progress in anticancer drug development for patients with metastatic castration-resistant prostate cancer (CRPC). However, the current instruments to assess clinical treatment response have limitations and may not sufficiently reflect patient benefit. Our objective was to systematically identify tools to evaluate both patient benefit and clinical anticancer-treatment response as basis for an international consensus process and development of a specific pragmatic instrument for men with CRPC.

METHODS

PubMed, Embase and CINAHL were searched to identify currently available tools to assess anticancer-treatment benefit, other than standard imaging procedures and prostate-specific antigen measurements, namely quality of life (QoL), detailed pain assessment, physical function and objective measures of other complex cancer-related syndromes in patients with CRPC. Additionally, all CRPC phase III trials published in the last 5 years were reviewed as well as studies using physical function tools in a general cancer population. The PRIMSA statement was followed for the systematic review process.

RESULTS

The search generated 1096 hits, 185 full-text papers were screened and finally 73 publications were included. Additional 89 publications were included by hand-search. We identified a total of 98 tools used in CRPC trials and grouped these into three categories: 22 tools assessing QoL domains and subgroups, 47 tools for pain assessment and 29 tools for objective measures, mainly physical function and assessment of skeletal disease burden.

CONCLUSION

A wide variety of assessment tools and also efforts to standardize and harmonize patient-reported outcomes and pain assessment were identified. However, the specific needs of the increasing CRPC population living longer with their incurable cancer are insufficiently captured and objective physical outcome measures are under-represented. In the age of new anticancer drug targets and principles, new methods to monitor patient relevant outcomes of antineoplastic therapy are of utmost importance.

Bone-modifying agents in the treatment of bone metastases in patients with advanced genitourinary malignancies: a focus on zoledronic acid

Many patients with advanced genitourinary malignancies develop bone metastases, which can lead to potentially debilitating skeletal complications. Moreover, age-related bone loss and cancer treatments such as hormonal therapy for prostate cancer can weaken bone, placing patients at risk for osteoporotic fractures in addition to skeletal-related events (SREs) from bone metastases. Zoledronic acid, a bisphosphonate, is approved worldwide to reduce the risk of SREs in patients with bone metastases from solid tumors or bone lesions from multiple myeloma. Zoledronic acid, although underutilized in genitourinary malignancies, has long been the mainstay of treatment in patients with bone metastases, and can also help preserve bone during anticancer therapy. Recently, denosumab, a monoclonal antibody directed against the receptor activator of nuclear factor kappa-B ligand, was approved in the United States and the European Union for reducing the risk of SREs in patients with bone metastases from solid tumors. Denosumab (at a lower dose) is also approved in the European Union and the United States to treat androgen deprivation-induced bone loss in men with prostate cancer. In addition, preclinical rationale and emerging clinical data suggest that bone-modifying agents may be able to delay disease progression in genitourinary cancers, just as newly developed anticancer treatments have produced reductions in SREs, possibly by indirect effects on the disease course. This review article summarizes current data and ongoing studies to preserve bone health in patients with advanced genitourinary cancers.

Bisphosphonates: prevention of bone metastases in prostate cancer

Bone metastases and their associated morbidities are common in patients with advanced prostate cancer and other genitourinary (GU) malignancies. Zoledronic acid> (a bisphosphonate) has long been the mainstay of treatment for reducing the risk of skeletal-related events in patients with bone metastases from GU cancers, and denosumab (a monoclonal antibody directed against the receptor activator of nuclear factor kappa B ligand [RANKL]) has recently received approval for this indication in the United States. Preclinical data indicate that modifying the bone microenvironment may render it less conducive to metastasis, and emerging clinical findings suggest that the potential benefits from bone-directed therapies are not limited to reducing skeletal morbidity-these agents might help to improve survival and delay bone disease progression or even development of bone metastases (if used earlier in the disease course). This chapter reviews the rationale and recent clinical data supporting an antimetastatic role for bone-directed therapies in patients with GU malignancies.

Pain in castration-resistant prostate cancer with bone metastases: a qualitative study

BACKGROUND

Bone metastases are a common painful and debilitating consequence of castration-resistant prostate cancer (CPRC). Bone pain may predict patients' prognosis and there is a need to further explore CRPC patients' experiences of bone pain in the overall context of disease pathology. Due to the subjective nature of pain, assessments of pain severity, onset and progression are reliant on patient assessment. Patient reported outcome (PRO) measures, therefore, are commonly used as key endpoints for evaluating the efficacy of CRPC treatments. Evidence of the content validity of leading PRO measures of pain severity used in CRPC clinical trials is, however, limited.

METHODS

To document patients' experience of CRPC symptoms including pain, and their impact on health-related quality of life (HRQL), semi-structured in-depth qualitative interviews were conducted with 17 patients with CRPC and bone metastases. The content validity of the Present Pain Intensity (PPI) scale from the McGill Pain Questionnaire (MPQ), and the 'Average Pain' and 'Worst Pain' items of the Brief Pain Inventory Short-Form (BPI-SF) was also assessed.

RESULTS

Patients with CRPC and bone metastases present with a constellation of symptoms that can have a profound effect on HRQL. For patients in this study, bone pain was the most prominent and debilitating symptom associated with their condition. Bone pain was chronic and, despite being generally well-managed by analgesic medication, instances of breakthrough cancer pain (BTcP) were common. Cognitive debriefing of the selected PRO measures of pain severity highlighted difficulties among patients in understanding the verbal response scale (VRS) of the MPQ PPI scale. There were also some inconsistencies in the way in which the BPI-SF 'Average Pain' item was interpreted by patients. In contrast, the BPI-SF 'Worst Pain' item was well understood and interpreted consistently among patients.

CONCLUSIONS

Study findings support the importance of PRO measures of pain severity as key endpoints for evaluating the efficacy of treatments for CRPC, particularly for patients with bone metastases where episodes of BTcP are common. Qualitative evidence from CRPC patients supports the content validity of the BPI-SF ''Worst Pain' item and promotes use of this item for measuring pain severity in this population.

Burden of metastatic bone disease from genitourinary malignancies

Bone metastases are common among patients with stage IV genitourinary cancers. Most patients with bone metastases develop at least one debilitating and potentially life-limiting skeletal-related event. These events are associated with increased medical expenses and decreased quality of life. Current guidelines recommend screening for bone metastases in men with high-risk prostate cancer, but guidance for screening and treatment of bone metastases from genitourinary cancers varies by country and setting. Several bisphosphonates have been evaluated in the advanced genitourinary cancer setting. Zoledronic acid has demonstrated efficacy in significantly reducing the risk of skeletal-related events in patients with bone metastases from a broad range of solid tumors including prostate, renal and bladder cancers, and is recommended for preserving bone health.

Targeting angiogenesis-dependent calcified neoplasms using combined polymer therapeutics

BACKGROUND

There is an immense clinical need for novel therapeutics for the treatment of angiogenesis-dependent calcified neoplasms such as osteosarcomas and bone metastases. We developed a new therapeutic strategy to target bone metastases and calcified neoplasms using combined polymer-bound angiogenesis inhibitors. Using an advanced "living polymerization" technique, the reversible addition-fragmentation chain transfer (RAFT), we conjugated the aminobisphosphonate alendronate (ALN), and the potent anti-angiogenic agent TNP-470 with N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer through a Glycine-Glycine-Proline-Norleucine linker, cleaved by cathepsin K, a cysteine protease overexpressed at resorption sites in bone tissues. In this approach, dual targeting is achieved. Passive accumulation is possible due to the increase in molecular weight following polymer conjugation of the drugs, thus extravasating from the tumor leaky vessels and not from normal healthy vessels. Active targeting to the calcified tissues is achieved by ALN's affinity to bone mineral.

METHODS AND FINDING

The anti-angiogenic and antitumor potency of HPMA copolymer-ALN-TNP-470 conjugate was evaluated both in vitro and in vivo. We show that free and conjugated ALN-TNP-470 have synergistic anti-angiogenic and antitumor activity by inhibiting proliferation, migration and capillary-like tube formation of endothelial and human osteosarcoma cells in vitro. Evaluation of anti-angiogenic, antitumor activity and body distribution of HPMA copolymer-ALN-TNP-470 conjugate was performed on severe combined immunodeficiency (SCID) male mice inoculated with mCherry-labeled MG-63-Ras human osteosarcoma and by modified Miles permeability assay. Our targeted bi-specific conjugate reduced VEGF-induced vascular hyperpermeability by 92% and remarkably inhibited osteosarcoma growth in mice by 96%.

CONCLUSIONS

This is the first report to describe a new concept of a narrowly-dispersed combined polymer therapeutic designed to target both tumor and endothelial compartments of bone metastases and calcified neoplasms at a single administration. This new approach of co-delivery of two synergistic drugs may have clinical utility as a potential therapy for angiogenesis-dependent cancers such as osteosarcoma and bone metastases.

Effect of bisphosphonates on pain and quality of life in patients with bone metastases

Bone is the most common organ for tumor metastasis, especially in patients with cancers of the breast or prostate. Bone metastases disrupt skeletal metabolism and result in considerable skeletal morbidity, including intractable, chronic bone pain, hypercalcemia of malignancy, pathologic fracture and spinal-cord compression. In addition to the chronic pain caused by bone metastases, skeletal-related events (SREs) such as pathologic fractures and spinal-cord compression can result in acute increases in pain. These effects can severely impair mobility and contribute to a general decrease in quality of life. Palliative options to treat bone metastases include radiotherapy, analgesics, surgery and bisphosphonates. These drugs bind to the surface of the bone and impair osteoclast-mediated bone resorption, and reduce the tumor-associated osteolysis that is initiated by the development of skeletal metastases. In addition to preventing SREs, bisphosphonates can palliate bone pain caused by a variety of solid tumors. This Review summarizes the clinical trial data of bisphosphonates for the prevention of SREs and the palliation of bone pain. Among these agents, nitrogen-containing bisphosphonates are recognized as the most effective, and zoledronic acid has demonstrated the broadest clinical utility.

Impact of skeletal complications on patients' quality of life, mobility, and functional independence

INTRODUCTION

Skeletal-related events (SREs) from malignant bone disease cause considerable morbidity and can dramatically reduce patients' quality of life.

DISCUSSION

Pathologic fractures often require surgical intervention and palliative radiotherapy. Thus, patients suffer impaired mobility, loss of functional independence, and diminished health-related quality of life (HRQOL). Bisphosphonates can delay the onset and reduce the incidence of SREs and have become the standard of care for the treatment of malignant bone disease; however, minimal information on the effects of bisphosphonate treatment on HRQOL is available. Targeted HRQOL assessments for patients with malignant bone disease are currently under development and are discussed herein.

New research findings on zoledronic acid: survival, pain, and anti-tumour effects

OBJECTIVES

To summarize the current evidence for clinical, anti-tumour, and survival benefits from zoledronic acid in patients with genitourinary cancers.

METHODS

Studies were identified through MEDLINE searches, review of bibliographies of relevant articles, and review of abstracts from scientific meetings.

RESULTS

Among patients with bone metastases from prostate cancer or renal cell carcinoma, zoledronic acid significantly delayed the onset and reduced the incidence of skeletal complications compared with placebo. Zoledronic acid is also the only bisphosphonate that has demonstrated a trend toward improved survival and delayed progression of bone lesions in patients with urologic malignancies. Furthermore, zoledronic acid reduced the incidence of pathologic fracture, a skeletal-related event known to be associated with reduced survival. Bisphosphonates have also demonstrated significant palliative benefits, and preclinical evidence indicates that bisphosphonates may have direct anti-tumour effects.

CONCLUSIONS

Zoledronic acid is the only bisphosphonate that has demonstrated statistically significant, long-term clinical benefits through the prevention and delay of skeletal-related events in patients with metastatic prostate cancer or renal cell carcinoma.