The Oncologist, Vol. 10, No. 1, 52-62, January 2005; doi:10.1634/theoncologist.10-1-52 © 2005 AlphaMed Press
Recommendations for Zoledronic Acid Treatment of Patients with Bone MetastasesOn behalf of the Monterey Zoledronic Acid Advisory Board; Institute for Myeloma & Bone Cancer Research, West Hollywood, California, USA Correspondence: James R. Berenson, M.D., Institute for Myeloma & Bone Cancer Research, 9201 W. Sunset Boulevard, Suite 300, West Hollywood, California 90069, USA. Telephone: 310-623-1214; Fax: 310-623-1120; e-mail: jberenson{at}myelomasource.org
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The introduction of zoledronic acid, a new-generation bisphosphonate, has greatly extended the use of bisphosphonates in the treatment of patients with bone metastases. On the basis of results from three large, randomized, phase III clinical trials enrolling more than 3,000 patients, zoledronic acid (4 mg via 15-minute infusion) was approved in the United States for the treatment of patients with documented bone metastases from solid tumors in conjunction with standard antineoplastic therapy and patients with multiple myeloma. Zoledronic acid is also approved in Europe for the prevention of skeletal-related events in patients with advanced malignancies involving bone. Current treatment guidelines published by the American Society of Clinical Oncology recommend the use of intravenous bisphosphonates at first radiographic evidence of osteopenia in patients with multiple myeloma or osteolytic bone lesions in patients with breast cancer to significantly reduce the occurrence and delay the onset of skeletal complications. Zoledronic acid has also demonstrated efficacy in the treatment of bone metastases in patients with prostate cancer, lung cancer, and other solid tumors. Bisphosphonate therapy is generally well tolerated but can be associated with increases in serum creatinine. Therefore, monitoring renal function is required for all patients receiving bisphosphonate therapy. Serum creatinine should be monitored before each dose and treatment withheld until any serum creatinine elevations have resolved to baseline levels. Caution should be exercised when treating patients who are receiving other potentially nephrotoxic therapies. With these simple precautions, intravenous bisphosphonate therapy is safe for long-term use and provides durable treatment benefits. Key Words. Bisphosphonate • Guidelines • Pamidronate • Renal safety • Zoledronic acid
Skeletal complications contribute substantially to the burden of disease in patients with bone metastases from solid tumors and in patients with multiple myeloma. Bone metastases are the most common cause of cancer-related pain [1] and often require palliative radiotherapy. Patients with advanced cancer involving bone frequently develop painful and debilitating pathologic fractures and spinal cord compression that can seriously limit mobility and may require surgical intervention. These and other skeletal complications contribute to the deterioration in quality of life and independence of many cancer patients [2]. Median survival after the development of bone metastases ranges from 648 months, depending on tumor type [2]. Malignant bone disease can result in chronic morbidity that often requires repeated interventions over several years. Approximately half of all patients with solid tumors that metastasize to bone experience one or more skeletal events (including pathologic fractures, spinal cord compression, radiotherapy or surgery to bone, and hypercalcemia) during the course of their disease [3, 4]. The incidence of these skeletal events varies depending on the type of primary cancer. For example, patients with predominantly osteolytic bone metastases secondary to advanced breast cancer are at high risk. Without bisphosphonate therapy, these patients will experience an average of four skeletal events, including two pathologic fractures, each year [4]. Patients with multiple myeloma, or bone metastases from prostate cancer, lung cancer, or renal cell carcinoma (RCC) are also at high risk of skeletal complications. Patients with multiple myeloma experience an average of two skeletal events per year [5, 6], and patients with prostate cancer have a mean annual incidence of 1.5 events per year [7]. Notably, approximately 80% of patients with bone metastases from RCC will develop a skeletal complication without bisphosphonate therapy [8]. Currently available palliative therapies for patients with malignant bone disease include radiation, chemotherapy, hormone therapy, orthopedic surgery, and i.v. bisphosphonates. Bisphosphonate therapy has emerged as an important component of the overall management strategy for malignant bone disease. Randomized, placebo-controlled trials have shown that when i.v. bisphosphonates are administered in conjunction with standard anticancer therapy, the incidence of skeletal complications is significantly reduced. Pamidronate has been widely used as palliative therapy in patients with osteolytic lesions from multiple myeloma or metastatic breast cancer, based on evidence that 90 mg pamidronate every 34 weeks significantly reduced the incidence and delayed the onset of skeletal complications in these patients compared with placebo [3, 4, 6, 9]. Moreover, bisphosphonates have been shown in a variety of studies to have analgesic effects on bone pain in patients with bone metastases [10]. Until recently, other than in breast cancer or multiple myeloma, no bisphosphonate has demonstrated significant clinical benefits for cancer patients whose cancer has metastasized to bone (e.g., prostate, lung, and renal cancers). Recently, the clinical benefits of a new-generation bisphosphonate, i.e., zoledronic acid, have been extended to patients with bone metastases secondary to a broad range of solid tumors including prostate cancer, lung cancer, and RCC. Zoledronic acid recently received broad regulatory approval for the treatment of bone metastases secondary to all solid tumor types and bone lesions from multiple myeloma based on the results of three large, randomized, phase III clinical trials enrolling more than 3,000 patients. These trials demonstrated that zoledronic acid (4 mg via 15-minute i.v. infusion every 34 weeks) effectively reduced the incidence of skeletal complications associated with malignant bone disease for patients with breast cancer, multiple myeloma, prostate cancer, or solid tumors other than breast or prostate cancer [7, 11, 12]. The primary efficacy end point in all three trials was the proportion of patients who experienced at least one skeletal-related event (SRE), defined as a pathologic fracture, spinal cord compression, radiotherapy to bone, or surgery to bone. Change in antineoplastic therapy to palliate bone pain was also included as an SRE only in the trial evaluating patients with prostate cancer. Hypercalcemia of malignancy (HCM) was included as an SRE in the analysis of secondary end points, including time to first SRE, the mean annual incidence of SREs (i.e., skeletal morbidity rate), and a multiple event analysis using the Andersen-Gill method. Multiple event analysis takes into account all clinically relevant SREs and the time to each event over a period of time, thereby providing a rigorous and sensitive assessment of skeletal morbidity. These three international trials were the largest bisphosphonate trials ever conducted, and unlike the previous pamidronate trials, they included patients with all types of bone lesions (i.e., osteolytic, mixed, and osteoblastic based on their radiographic appearance). In the first of these trials to be published, zoledronic acid was compared with pamidronate in 1,648 patients with stage IV breast cancer with at least one bone lesion or Durie-Salmon stage III multiple myeloma. The results from this trial at 13 months demonstrated that zoledronic acid (4 mg via 15-minute infusion) was at least as effective as pamidronate (90 mg via 2-hour infusion) in the overall efficacy analysis, with a similar safety profile [11]. In addition, zoledronic acid significantly reduced the incidence of radiotherapy to bone compared with pamidronate (15% versus 20%; p = 0.031). Most notably, multiple event analysis showed that zoledronic acid significantly reduced the risk of developing SREs by an additional 16% (p = 0.030) compared with pamidronate during the 24 months of treatment [13, 14]. Zoledronic acid was compared with placebo in 643 patients with bone metastases from prostate cancer that had progressed during hormone therapy [7]. These patients develop primarily osteoblastic lesions. Zoledronic acid (4 mg) significantly reduced the proportion of patients who experienced at least one SRE at 15 months compared with placebo (33% versus 44%; p = 0.021), and zoledronic acid displayed consistent efficacy across all secondary end points. The majority of SREs in this patient population were pathologic fractures and radiation to bone. Of note, 22% of patients in the placebo group had a fracture in the first 15 months compared with 13% of patients treated with 4 mg zoledronic acid (p = 0.015). Patients treated with zoledronic acid also had lower mean pain scores (Brief Pain Inventory composite score) compared with placebo at every time point, and these differences were statistically significant (p < 0.05) at the 3- and 9-month time points. This is the first randomized, placebo-controlled trial to demonstrate that a bisphosphonate can provide objective and durable clinical benefits to patients with prostate cancer with bone metastases. In the most recently published of these phase III trials, zoledronic acid was compared with placebo in 773 patients with bone metastases secondary to solid tumors other than breast or prostate cancer (including lung, renal, and bladder cancers) [12]. Half of the patients enrolled in this study had non-small cell lung cancer (NSCLC), and median survival was only approximately 6 months for the entire patient population. Although the primary end point did not reach statistical significance when HCM was excluded from the analysis, 4 mg zoledronic acid significantly decreased the proportion of patients who experienced an SRE compared with placebo when HCM was included in the analysis (38% versus 47%; p = 0.039). Zoledronic acid also significantly prolonged time to first SRE; the median time was prolonged by more than 2 months (p = 0.007) [15], which may be a more meaningful assessment of treatment effect in this poor-prognosis patient population [12]. Furthermore, in the overall patient population and the NSCLC stratum, multiple event analysis demonstrated that treatment with 4 mg zoledronic acid significantly reduced the risk of developing SREs by 29% compared with placebo (p = 0 .036) [16]. On the basis of results from these trials, zoledronic acid is emerging as the new standard of care for managing skeletal morbidity in patients with advanced cancers involving bone. Zoledronic acid has also been shown to reduce skeletal morbidity in patients with both osteolytic and osteoblastic bone lesions [17]. Zoledronic acid can be safely administered via a 15-minute infusion, compared with the minimum recommended infusion time of 2 hours for pamidronate. Since receiving U.S. and European regulatory approval, zoledronic acid has been used to treat >800,000 patients with bone metastases. In the context of its widespread application, we have developed treatment recommendations for zoledronic acid therapy to ensure safety and efficacy, based on the available data.
The infusion protocol for zoledronic acid has been standardized and is now available online at http://www.us.zometa.com/hcp/productinfo/infusioninstructions.jsp. Preinfusion assessments include a physical examination, vital signs, and laboratory testing of serum creatinine levels and hydration status. Because all i.v. bisphosphonates have the potential to cause an increase in serum creatinine and patients with serum creatinine 3.0 mg/dl were excluded from the phase III zoledronic acid trials, patients must be adequately hydrated and have serum creatinine levels <3.0 mg/dl (<4.5 mg/dl in patients with HCM [18] if the benefits of treatment are considered to outweigh the risk) before receiving i.v. bisphosphonates. Patients should be encouraged to drink two glasses of water before receiving their bisphosphonate infusion, but i.v. hydration is not typically necessary. The maximum recommended dose of zoledronic acid for the treatment of bone metastases or hypercalcemia of malignancy is 4 mg infused over no less than 15 minutes. Zoledronic acid powder (4 mg) can easily be reconstituted in 5 ml sterile water for injection USP and diluted in no less than 100 ml of 0.9% sodium chloride USP or 5% dextrose injection USP [11]. A concentrated solution of zoledronic acid (4 mg in 5 ml sterile water) is also available, eliminating the need for reconstitution. A 5-ml aliquot of the concentrate (4 mg zoledronic acid) should be mixed with 100 ml of calcium-free diluent before infusion. If not used immediately, the diluted solution can be stored in the refrigerator and should be re-equilibrated to room temperature and infused within 24 hours [19]. A peripheral i.v. line should be inserted and the diluted zoledronic acid solution infused over 15 minutes. The patients vital signs and the i.v. site should be monitored periodically during the infusion and again after the infusion has been completed.
Zoledronic acid has the shortest infusion time of any i.v. bisphosphonate (Table 1
The role of bisphosphonate therapy in the treatment of malignant bone disease has evolved over the past several years. With the introduction of zoledronic acid, all patients with bone metastases secondary to solid tumors or bone lesions from multiple myeloma can potentially benefit from bisphosphonate therapy. Because of the substantial burden of skeletal complications in patients with malignant bone disease and improvements in bisphosphonate therapy, treatment guidelines were recently established by the American Society of Clinical Oncology (ASCO) [25, 26]. According to these ASCO guidelines, all patients with multiple myeloma who have radiographic evidence of osteolytic bone disease or osteopenia in the absence of radiographically detectable bone disease should receive i.v. bisphosphonate therapy [25]. For patients with breast cancer, bisphosphonate therapy should be initiated at the first radiographic evidence of bone destruction or an abnormal bone scan with localized pain [26]. Patients who are receiving bisphosphonate therapy should continue to do so throughout the course of their disease as long as it is tolerated [25, 26]. Although no guidelines have been developed for patients with solid tumors other than breast cancer, treatment with zoledronic acid at the first diagnosis of metastatic bone disease is a reasonable approach supported by the results of the large phase III trials of zoledronic acid in prostate cancer and in lung cancer or other solid tumors [7, 15]. Therefore, all patients with advanced cancer should have periodic radiographic evaluations to detect bone lesions. In a recent study of prostate cancer patients without evidence of bone metastases who were receiving androgen deprivation therapy, administration of zoledronic acid (4 mg every 3 months) significantly increased bone mineral density [27], suggesting that bisphosphonates may be beneficial even earlier in the course of therapy, before bone metastases develop.
Recommendations for zoledronic acid administration that are consistent with the above guidelines and the available clinical data are summarized in Table 2
Although zoledronic acid therapy is widely recommended for patients with malignant bone disease and is generally safe and well tolerated with long-term use, it is contraindicated in patients with clinically significant hypersensitivity to zoledronic acid or other bisphosphonates and is not recommended for patients with severe renal impairment. Patients with serum creatinine >3.0 mg/dl were excluded from the phase III clinical trials [7, 11, 12]. Therefore, there are no prospective data on the safety of zoledronic acid in these patients. However, for patients with serum creatinine >3.0 mg/dl who are considered at high risk of developing skeletal complications, the potential benefits of zoledronic acid may outweigh the risk of any potential adverse effects on renal function. For example, patients with life-threatening HCM and patients with extensive osteolytic lesions at weight-bearing bone sites may be considered at high risk, and zoledronic acid therapy may be initiated at the physicians discretion despite pre-existing renal impairment. Because of the inherent prevalence of renal impairment and the widespread use of potentially nephrotoxic therapies in patients with multiple myeloma, clinical experience suggests that zoledronic acid should be administered cautiously in that patient population, especially in those receiving thalidomide therapy. Renal function monitoring guidelines will be discussed further in the section on managing adverse events.
Caution should be exercised when starting bisphosphonate therapy or when switching from one bisphosphonate to another in patients who have other renal-related risk factors (refer to guidelines in Table 2
Bisphosphonate therapy is associated with mainly mild to moderate adverse events. The safety profile of zoledronic acid has been well established, based on randomized controlled trials and the collective experiences of more than 800,000 patients treated with zoledronic acid. Recommendations have been developed (Table 2
Acute-Phase Reactions
Effects on Renal Function A less common but potentially serious adverse event is decreased renal function, which may occur after the administration of any i.v. bisphosphonate. Adherence to the renal monitoring guidelines will minimize the risk of renal sequelae. Approximately 10% of patients treated with zoledronic acid (4 mg via 15-minute infusion) develop renal function deterioration (defined as an increase of 0.5 mg/dl in patients with normal baseline serum creatinine [<1.4 mg/dl] or an increase of 1.0 mg/dl in patients with abnormal baseline serum creatinine [ 1.4 mg/dl]) during the course of their treatment, similar to the frequency reported for patients treated with 90 mg pamidronate via 2-hour infusion [11]. Furthermore, the time to first increase in serum creatinine was similar during 4-mg zoledronic acid or 90-mg pamidronate treatment (Fig. 1 grade 3 serum creatinine elevations (i.e., > three times the upper limit of normal according to the National Cancer Institute common toxicity criteria) [19]. Furthermore, in the two placebo-controlled trials of patients with bone metastases from prostate cancer or other solid tumors (not including breast cancer), increases in serum creatinine occurred in considerable proportions of patients in the placebo groups (12.8% and 7.4%, respectively), suggesting that underlying disease-related factors may contribute to the incidence of renal impairment in patients with advanced cancer [7, 15]. Moreover, in the more than 800,000 patients treated with zoledronic acid, spontaneous renal function impairment has been uncommon, and nearly half of these cases were in patients with multiple myeloma, a disease associated with increased risk of renal failure [30, 31]. Although the information on these events is limited, many occurred in patients who had abnormal serum creatinine ( 1.4 mg/dl) at baseline or who had previously received long-term treatment with pamidronate. Therefore, there may be an increased risk of renal impairment in patients with abnormal serum creatinine at baseline, and prior long-term bisphosphonate therapy may predispose patients to decreased renal function.
Renal Monitoring Guidelines Renal monitoring guidelines have been established to minimize the risk of renal deterioration during bisphosphonate therapy (Table 2 0.5 mg/dl, and from patients with abnormal baseline serum creatinine whose levels have increased by 1.0 mg/dl. The zoledronic acid infusion can be resumed after serum creatinine has returned to within 10% of baseline, which may take from several weeks to months to occur. A slower infusion time may reduce the risk of further episodes of rises in serum creatinine. In patients who are receiving potentially nephrotoxic therapies or who have abnormal renal function at baseline, additional considerations must be made. At this time, there are insufficient clinical data to generate specific renal monitoring recommendations for zoledronic acid in patients receiving nephrotoxic drugs such as radiographic contrast media. If possible, zoledronic acid and nephrotoxic drugs should not be administered on the same day. Anecdotal evidence from clinical experience and a small open-label trial suggest that concomitant therapy with thalidomide may potentiate adverse renal effects [32]. However, in the phase III clinical trial setting, concomitant therapy with thalidomide was not identified as a risk factor in patients with multiple myeloma [11]. Drugs with the potential for renal toxicity, such as NSAIDs, should also be administered with caution to patients who are receiving zoledronic acid, and use of these chronically administered medications may need to be avoided around the time of i.v. bisphosphonate therapy. Waiting 24 hours after the administration of zoledronic acid before administering any drugs that are potentially nephrotoxic may minimize the risk of renal impairment. Further, clinical experiences suggest that increasing the infusion time for zoledronic acid from 15 to 30 minutes may possibly further reduce the risk of serum creatinine increases in these patients. However, this has not been confirmed in controlled studies.
Other Adverse Events
Adverse Events Can Be Minimized by Adherence to Administration Guidelines The proper administration, dose, and schedule of zoledronic acid are crucial to minimize the incidence and severity of adverse events. Zoledronic acid can be safely administered at a dose of 4 mg with a minimum infusion time of 15 minutes every 34 weeks. Although a shorter infusion time (i.e., 5 minutes) was investigated in phase I and II clinical trials [3335], infusion times <15 minutes resulted in an increased incidence of serum creatinine elevations during the early stages of phase III clinical testing and therefore are not recommended [7, 11]. Furthermore, in the phase III trials, administration of 8 mg zoledronic acid did not provide any treatment benefit over that achieved with 4 mg, but did increase the incidence of elevated serum creatinine and renal adverse events [7, 11]. Therefore, the 8-mg dose is not recommended for clinical use at this time using any infusion duration. Ongoing monitoring of serum creatinine, serum ion levels, and hydration status are recommended to minimize adverse events with patients receiving any i.v. bisphosphonate.
Duration of Bisphosphonate Therapy
Zoledronic acid is the first bisphosphonate to demonstrate significant and durable clinical benefit in reducing skeletal complications for patients with malignant bone involvement from multiple myeloma and a variety of solid tumors, including breast cancer, prostate cancer, and lung cancer [7, 11, 12]. Treatment with zoledronic acid can prevent or delay debilitating skeletal complications, and therefore may slow the erosion of quality of life experienced by patients with advanced cancer involving the bone. Importantly, long-term treatment with zoledronic acid has been shown to be safe and well tolerated during its widespread use in clinical practice. Adherence to renal monitoring will ensure renal safety. The development of an effective and safe i.v. bisphosphonate therapy that can be administered in only 15 minutes is an important therapeutic advance that provides a direct quality-of-life benefit to the patient. Furthermore, the 15-minute infusion protocol for zoledronic acid has renal and overall safety profiles similar to those of the 2-hour infusion of pamidronate, the former standard of care for patients with breast cancer or multiple myeloma [11]. In summary, with the proper dose, schedule, and patient monitoring, zoledronic acid represents an important advance in the management of patients with bone metastases.
James Berenson receives research grants and honoraria and is on the advisory board for Novartis. The authors wish to thank all of the participants on the Monterey Zoledronic Acid Advisory Board for their insight and input: Dr. Per-Anders Abrahamsson, Malmo University Hospital, Sweden; Dr. Joan Albanell, Medical Oncology Service, Spain; Dr. Brent Blumenstein, Duke University Medical Center, USA; Dr. Pier Franco Conte, UO Oncologia Medica Ospedale, S. Chiara, Italy; Dr. Richard Cook, University of Waterloo, Canada; Dr. Ingo J. Diel, CCG-Klinik GmbH, Germany; Dr. Manuel Domine, Spain; Dr. Brent Eilersten, Denmark; Dr. Karim Fizaz, France; Dr. Gunther Gastl, Innsbruck University Hospital, Austria; Dr. Stephen J. Hartland, Middlesex Hospital, UK; Dr. Adrian Harnett, Norfolk and Norwich Hospital, UK; Dr. Alex Heidenreich, Germany; Dr. Celestia Higano, University of Washington Cancer Center, USA; Dr. David Joseph, Sir Charles Gairdner Hospital, Australia; Dr. S. Ming Lee, Middlesex Hospital, UK; Dr. Michael Lein, University Hospital Charite, Germany; Dr. Allan Lipton, Milton S. Hershey Medical Center, USA; Dr. Hironobu Minami, National Cancer Center Hospital East, Japan; Dr. Phillip Moreau, C.H.U. Hospital Hotel-Dieu, France; Professor Jean-Francois Morere, Service Domologie Medicale, France; Dr. Robin Murray, Peter MacCallum Cancer Institute, Australia; Dr. Emilio Palazzo, Cordoba Private Hospital, Argentina; Dr. Kishan Pandya, University of Rochester Medical Center, USA; Dr. G. David Roodman, University of Pittsburgh Cancer Institute, USA; Dr. Victoria Schaffer; Dr. Matthew Smith, Massachusetts General Hospital, USA; Dr. Andrew Spencer, Alfred Hospital, Australia; Dr. Maureen Trudeau, Toronto-Sunnybrook Regional Cancer Centre, Canada; Dr. Christine VandePol, Enpharma Consulting, USA; and Dr. Jefferson Vinholes, Brazil.
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