Zoledronic acid: an advance in tumour bone disease therapy and a new hope for osteoporosis

Management of bone health in solid tumours: From bisphosphonates to a monoclonal antibody

Patients with solid tumours are at risk of impaired bone health from metastases and cancer therapy-induced bone loss (CTIBL). We review medical management of bone health in patients with solid tumours over the past 30 years, from first-generation bisphosphonates to the receptor activator of nuclear factor κB ligand (RANKL)-targeted monoclonal antibody, denosumab. In the 1980s, first-generation bisphosphonates were shown to reduce the incidence of skeletal-related events (SREs) in patients with breast cancer. Subsequently, more potent second- and third-generation bisphosphonates were developed, particularly zoledronic acid (ZA). Head-to-head studies showed that ZA was significantly more effective than pamidronate for reducing SREs in patients with breast and castrate-resistant prostate cancer (CRPC), becoming the standard of care for more than a decade. The RANKL inhibitor denosumab was licensed in 2010, and head-to-head studies and integrated analyses confirmed its superiority to ZA for preventing SREs, particularly in breast cancer and CRPC. Bisphosphonates and denosumab have also been investigated for prevention of CTIBL in patients receiving hormonal therapy for breast and prostate cancer, and denosumab is licensed in this indication. Despite advances in management of bone health, several issues remain, notably the optimal time to initiate therapy, duration of therapy, and dosing frequency, and how to avoid toxicity, particularly with long-term treatment. In summary, introduction of ZA and denosumab has protected patients with bone metastasis from serious bone complications and improved their quality of life. Ongoing research will hopefully guide the optimal use of these agents to help maintain bone health in patients with solid tumours.

Usefulness of Bone Formation Markers in Breast Cancer

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

The risk of cumulative renal effects of intravenous bisphosphonates

Some level of renal dysfunction is common in patients with cancer. This could be a result of an age-related kidney function decrease, the underlying disease (eg, multiple myeloma), or the effects of nephrotoxic medications. Some intravenous (I.V.) bisphosphonates have been associated with occasional renal toxicity in the clinical setting. Therefore, the choice of an I.V. bisphosphonate should take into account the risk of renal deterioration. Preclinical studies also suggest that there might be considerable differences between the renal safety profiles of commonly used I.V. bisphosphonates. Variations in the risk of histopathologic damage and the ability to cause cumulative toxicity have been observed in comparative preclinical studies of I.V. bisphosphonates. The reasons for these apparent differences are not fully understood. Research shows that renal safety profiles might be influenced by pharmacokinetic properties, such as renal tissue half-life, protein binding, and intracellular potency. Preclinical analyses are warranted in order to confirm and evaluate these differences between bisphosphonates.

A prospective analysis of CT density measurements of bone metastases after treatment with zoledronic acid

OBJECTIVE

The objective was to prospectively determine CT density changes in bone metastases, before and after intravenous zoledronic acid for a maximum period of 12 months.

PATIENTS AND METHODS

Twenty-three consecutive patients presented with bone metastases and underwent therapy with zoledronic acid from December 2004. All patients underwent CT of the chest, abdomen, and pelvis. Bone density, measured in Hounsfield units (HU), was determined by segmenting lesions in the same anatomical area of the metastasis sites on the axial images of the sequential series of CT examinations. The effects of zoledronic acid were evaluated by calculating absolute and relative increases in bone density.

RESULTS

The patients presented with multiple metastases in 65% of the cases. When compared with the baseline, all groups demonstrated a significant increase in bone density, which significantly (p < 0.01) correlated with the number of zoledronic acid administrations. There was increased bone density of at least 100% in 57%, and an increase of at least 50% in 87% of the patients. This increase was significant in both lytic and sclerotic metastases after 3 months of therapy. No significant bone density difference was found in normal-appearing bone.

CONCLUSION

Bone density measured by CT increases at metastatic sites after zoledronic acid treatment, regardless of the type of metastasis, in contrast to apparently normal bone.

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

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

The Changing Treatment Paradigm in Patients With Newly Diagnosed Multiple Myeloma: Implications for Nursing

PURPOSE/OBJECTIVES

To review the changing treatment paradigm for newly diagnosed multiple myeloma and its implications for nursing.

DATA SOURCES

Journal articles, textbooks, published research data.

DATA SYNTHESIS

The treatment approaches to newly diagnosed multiple myeloma are varied, and no consensus exists about the best choice of induction therapy prior to high-dose chemotherapy with autologous stem cell transplantation. Novel therapies that have shown strong clinical activity in patients with relapsed or refractory myeloma currently are being explored as first-line therapy with associated higher incidence of serious complications.

CONCLUSIONS

Novel approaches in the treatment of newly diagnosed multiple myeloma may lead to better overall patient survival. Research is ongoing to find ways to improve progression-free and overall survival in patients with multiple myeloma.

IMPLICATIONS FOR NURSING

Oncology nurses play vital roles in the assessment and monitoring of serious complications associated with various therapies for patients with newly diagnosed multiple myeloma. Key responsibilities include safe and effective administration of complex chemotherapeutic regimens, management of side effects, patient and family education, and coordination of a multidisciplinary approach.

Breast cancer: bisphosphonate therapy for metastatic bone disease

The indications of bisphosphonate therapy in breast cancer patients go from the correction of hypercalcemia to the prevention of cancer treatment-induced bone loss. Bisphosphonates are part of our therapeutic armamentarium against metastatic bone pain, and at least 50% of the patients benefit from a clinically relevant analgesic effect. Placebo-controlled trials with oral or i.v. bisphosphonates have shown that prolonged administration can reduce the frequency of skeletal-related events by 30% to 40%. The superiority of zoledronic acid compared with pamidronate has been shown by a multiple-event analysis in a large randomized trial. The short infusion time of zoledronic acid also constitutes a convenient therapy. Where available, oral ibandronate offers an interesting alternative, especially for patients receiving hormone therapy. There are some toxicity concerns with the prolonged use of bisphosphonates. The occasional renal toxicity of zoledronic acid has led to the recommendation to monitor renal function before each infusion and to adjust the dose according to creatinine clearance. Osteonecrosis of the jaw could occur in up to 2.5% of breast cancer patients during long-term bisphosphonate therapy. It is often a significant complication that seems to be linked with the duration of therapy.

Clodronate : a review of its use in the prevention of bone metastases and the management of skeletal complications associated with bone metastases in patients with breast cancer

Clodronate (clodronate disodium, Bonefos) is a non-nitrogen-containing bisphosphonate that inhibits osteoclast activity, and thereby inhibits bone resorption. Clodronate has been extensively used in patients with advanced breast cancer, and is generally well tolerated. In patients with primary breast cancer, clodronate is currently the only bisphosphonate shown to improve survival rates and to reduce the incidence of bone metastases in randomised controlled trials. Further trials in patients with early breast cancer are warranted to confirm results to date and to determine the optimal duration of treatment, as well as the efficacy of the drug compared with other bisphosphonates. In the meantime, clodronate is a well established bisphosphonate which has shown beneficial effects in the prevention of bone metastases and on survival in patients with primary breast cancer.

Primary hyperparathyroidism and neuropsychiatric alterations in a nonagenarian woman

Whether elderly patients with asymptomatic or minimally symptomatic primary hyperparathyroidism (PHPT) should be treated or not is still under debate. Several literature reports have shown improvements in terms of bone density and physical and mental well-being after surgical resolution of PHPT. Here, we present the case of a 93-year-old hypertensive woman, who had suffered for one year from cognitive impairment, accompanied during the last month by behavioral alterations (and polyuria and polydipsia), which resulted in sopor leading to hospitalization. A CT brain scan evidenced cortical atrophy and cerebrovascular disease, and biochemical analyses were remarkable for hypercalcemia (11.4-12.6 mg/dL, corrected for albumin levels) associated with increased parathormone levels (95.4-100.6 pg/mL). A diagnosis of PHPT was established. Densitometry evaluation of radius showed osteopenia. Withdrawal of psycho-therapy drugs and thiazidic, together with i.v. saline hydration and loop diuretics, significantly improved the patient's mental state and resolved behavioral alterations. As the patient and her relatives refused the surgical option, and the clinical situation improved after medical normalization of calcium levels, PHPT was managed conservatively, and calcium levels were maintained within the normal range through i.v. administration of zoledronate at 8-week intervals. Our case highlights the importance of considering hypercalcemia as the cause of onset of behavioral alterations and worsening of mental condition in elderly patients with cognitive decline. Therapy with bisphosphonates in patients with PHPT who are unfit for or refuse surgery seems advisable, but needs further study.

Hypercalcemia of malignancy

Less than 25 years ago tumor-induced hypercalcemia was often a lethal complication of cancer. Nowadays, it can be treated easily and successfully in at least 90% of cases by volume repletion in addition to the use of bisphosphonates that are potent anti-osteoclastic compounds. The standard therapy consists of the administration of 90 mg pamidronate or, more recently, 4 mg zoledronic acid, a more efficient bisphosphonate. When available, another alternative bisphosphonate is ibandronate. Recurrent hypercalcemia is nevertheless difficult to control and antibodies against parathyroid hormone-related protein could be useful for that matter in selected patients who are not in the terminal stage of their disease. Prevention of tumor-induced hypercalcemia is one of the objectives of long-term therapy with bisphosphonates in patients with tumor bone disease. The use of bisphosphonates in placebo-controlled trials has shown that the incidence of hypercalcemic episodes is reduced by more than one half.

Bisphosphonates antagonise bone growth factors' effects on human breast cancer cells survival

Bone tissue constitutes a fertile 'soil' for metastatic tumours, notably breast cancer. High concentrations of growth factors in bone matrix favour cancer cell proliferation and survival, and a vicious cycle settles between bone matrix, osteoclasts and cancer cells. Classically, bisphosphonates interrupt this vicious cycle by inhibiting osteoclast-mediated bone resorption. We and others recently reported that bisphosphonates can also induce human breast cancer cell death in vitro, which could contribute to their beneficial clinical effects. We hypothesised that bisphosphonates could inhibit the favourable effects of 'bone-derived' growth factors, and indeed found that bisphosphonates reduced or abolished the stimulatory effects of growth factors (IGFs, FGF-2) on MCF-7 and T47D cell proliferation and inhibited their protective effects on apoptotic cell death in vitro under serum-free conditions. This could happen through an interaction with growth factors' intracellular phosphorylation transduction pathways, such as ERK1/2-MAPK. In conclusion, we report that bisphosphonates antagonised the stimulatory effects of growth factors on human breast cancer cell survival and reduced their protective effects against apoptotic cell death. Bisphosphonates and growth factors thus appear to be concurrent compounds for tumour cell growth and survival in bone tissue. This could represent a new mechanism of action of bisphosphonates in their protective effects against breast cancer-induced osteolysis.