Zoledronic acid in the treatment of early-stage breast cancer: is there a final verdict?

MAF Amplification and Adjuvant Clodronate Outcomes in Early-Stage Breast Cancer in NSABP B-34 and Potential Impact on Clinical Practice

Background

The Adjuvant Zoledronic Acid (ZA) study in early breast cancer (AZURE) showed correlation between a nonamplified MAF gene in the primary tumor and benefit from adjuvant ZA. Adverse ZA outcomes occurred in MAF-amplified patients. NSABP B-34 is a validation study.

Methods

A retrospective analysis of MAF gene status in NSABP B-34 was performed. Eligible patients were randomly assigned to standard adjuvant systemic treatment plus 3 years oral clodronate (1600 mg/daily) or placebo. Tumors were tested for MAF gene amplification and analyzed for their relationship to clodronate for disease-free survival (DFS) and overall survival (OS) in MAF nonamplified patients. All statistical tests were 2-sided .

Results

MAF status was assessed in 2533 available primary tumor samples from 3311 patients. Of these, 37 withdrew consent; in 77 samples, no tumor was found; 536 assays did not meet quality standards, leaving 1883 (77.8%) evaluable for MAF assay by fluorescence in situ hybridization (947 from placebo and 936 from clodronate arms). At 5 years, in MAF nonamplified patients receiving clodronate, DFS improved by 30% (hazard ratio = 0.70, 95% confidence interval = 0.51 to 0.94; P = .02). OS improved at 5 years (hazard ratio = 0.59, 95% confidence interval = 0.37 to 0.93; P = .02) remaining statistically significant for clodronate throughout study follow-up. Conversely, adjuvant clodronate in women with MAF-amplified tumors was not associated with benefit but rather possible harm in some subgroups. Association between MAF status and menopausal status was not seen.

Conclusions

Nonamplified MAF showed statistically significant benefits (DFS and OS) with oral clodronate, supporting validation of the AZURE study.

Breast Cancer and Microcalcifications: An Osteoimmunological Disorder?

The presence of microcalcifications in the breast microenvironment, combined with the growing evidences of the possible presence of osteoblast-like or osteoclast-like cells in the breast, suggest the existence of active processes of calcification in the breast tissue during a woman’s life. Furthermore, much evidence that osteoimmunological disorders, such as osteoarthritis, rheumatoid arthritis, or periodontitis influence the risk of developing breast cancer in women exists and vice versa. Antiresorptive drugs benefits on breast cancer incidence and progression have been reported in the past decades. More recently, biological agents targeting pro-inflammatory cytokines used against rheumatoid arthritis also demonstrated benefits against breast cancer cell lines proliferation, viability, and migratory abilities, both in vitro and in vivo in xenografted mice. Hence, it is tempting to hypothesize that breast carcinogenesis should be considered as a potential osteoimmunological disorder. In this review, we compare microenvironments and molecular characteristics in the most frequent osteoimmunological disorders with major events occurring in a woman’s breast during her lifetime. We also highlight what the use of bone anabolic drugs, antiresorptive, and biological agents targeting pro-inflammatory cytokines against breast cancer can teach us.

A phase III multicenter, randomized, controlled study of combined androgen blockade with versus without zoledronic acid in prostate cancer patients with metastatic bone disease: results of the ZAPCA trial

OBJECTIVE

To examine the antitumor activity of zoledronic acid (ZA) combined with androgen deprivation therapy (ADT) for men with treatment-naive prostate cancer and bone metastasis.

METHODS

We enrolled 227 men with treatment-naive prostate cancer and bone metastasis. Participants were randomly assigned (1:1 ratio) to receive combined androgen blockade alone (CAB group) or ZA with combined androgen blockade (CZ group). Time to treatment failure (TTTF), time to the first skeletal-related event (TTfSRE), and overall survival (OS) rates were estimated using the Kaplan-Meier method. Hazard ratios (HRs) were calculated using the Cox proportional hazards model. Median follow-up duration was 41.5 months.

RESULTS

Median TTTFs were 12.4 and 9.7 months for the CZ and CAB groups, respectively (HR 0.75; 95 % CI 0.57-1.00; p = 0.051). For men with baseline prostate-specific antigen levels <200 ng/mL, median TTTFs were 23.7 and 9.8 months for the CZ and CAB groups, respectively (HR 0.58; 95 % CI 0.35-0.93; p = 0.023). Median TTfSREs were 64.7 and 45.9 months for the CZ and CAB groups, respectively (HR 0.58; 95 % CI 0.38-0.88; p = 0.009). OS was similar between the groups.

CONCLUSIONS

This study failed to demonstrate that combined use of ZA and ADT significantly prolonged TTTF in men with treatment-naive prostate cancer and bone metastasis. However, it generates a new hypothesis that the combined therapy could delay the development of castration resistance in a subgroup of patients with low baseline prostate-specific antigen values <200 ng/mL. The treatment also significantly prolonged TTfSRE but did not affect OS.

Adjuvant endocrine therapy for early breast cancer: a systematic review of the evidence for the 2014 Cancer Care Ontario systemic therapy guideline

BACKGROUND

Cancer Care Ontario's Program in Evidence-Based Care (pebc) recently created an evidence-based consensus guideline on the systemic treatment of early breast cancer. The evidence for the guideline was compiled using a systematic review to answer the question "What is the optimal systemic therapy for patients with early-stage, operable breast cancer, when patient and disease factors are considered?" The question was addressed in three parts: cytotoxic chemotherapy, endocrine treatment, and her2 (human epidermal growth factor receptor 2)-targeted therapy.

METHODS

For the systematic review, the literature in the medline and embase databases was searched for the period January 2008 to May 2014. The Standards and Guidelines Evidence directory of cancer guidelines and the Web sites of major oncology guideline organizations were also searched. The basic search terms were "breast cancer" and "systemic therapy" (chemotherapy, endocrine therapy, targeted agents, ovarian suppression), and results were limited to randomized controlled trials (rcts), guidelines, systematic reviews, and meta-analyses.

RESULTS

Several hundred documents that met the inclusion criteria were retrieved. Meta-analyses from the Early Breast Cancer Trialists' Collaborative Group encompassed many of the rcts found. Several additional studies that met the inclusion criteria were retained, as were other guidelines and systematic reviews.

SUMMARY

The results of the systematic review constitute a comprehensive compilation of high-level evidence, which was the basis for the 2014 pebc guideline on systemic therapy for early breast cancer. The review of the evidence for systemic endocrine therapy (adjuvant tamoxifen, aromatase inhibitors, and ovarian ablation and suppression) is presented here; the evidence for chemotherapy and her2-targeted treatment-and the final clinical practice recommendations-are presented separately in this supplement.

Clinical potential of novel therapeutic targets in breast cancer: CDK4/6, Src, JAK/STAT, PARP, HDAC, and PI3K/AKT/mTOR pathways

Breast cancers expressing estrogen receptor α, progesterone receptor, or the human epidermal growth factor receptor 2 (HER2) proto-oncogene account for approximately 90% of cases, and treatment with antiestrogens and HER2-targeted agents has resulted in drastically improved survival in many of these patients. However, de novo or acquired resistance to antiestrogen and HER2-targeted therapies is common, and many tumors will recur or progress despite these treatments. Additionally, the remaining 10% of breast tumors are negative for estrogen receptor α, progesterone receptor, and HER2 (“triple-negative”), and a clinically proven tumor-specific drug target for this group has not yet been identified. Therefore, the identification of new therapeutic targets in breast cancer is of vital clinical importance. Preclinical studies elucidating the mechanisms driving resistance to standard therapies have identified promising targets including cyclin-dependent kinase 4/6, phosphoinositide 3-kinase, poly adenosine diphosphate–ribose polymerase, Src, and histone deacetylase. Herein, we discuss the clinical potential and status of new therapeutic targets in breast cancer.

Treatment and Prevention of Bone Metastases from Breast Cancer: A Comprehensive Review of Evidence for Clinical Practice

Bone is the most common site of metastasis from breast cancer. Bone metastases from breast cancer are associated with skeletal-related events (SREs) including pathological fractures, spinal cord compression, surgery and radiotherapy to bone, as well as bone pain and hypercalcemia, leading to impaired mobility and reduced quality of life. Greater understanding of the pathophysiology of bone metastases has led to the discovery and clinical utility of bone-targeted agents such as bisphosphonates and the receptor activator of nuclear factor kappa-B ligand (RANK-L) antibody, denosumab. Both are now a routine part of the treatment of breast cancer bone metastases to reduce SREs. With regards to prevention, there is no evidence that oral bisphosphonates can prevent bone metastases in advanced breast cancer without skeletal involvement. Several phase III clinical trials have evaluated bisphosphonates as adjuvant therapy in early breast cancer to prevent bone metastases. The current published data do not support the routine use of bisphosphonates in unselected patients with early breast cancer for metastasis prevention. However, significant benefit of adjuvant bisphosphonates has been consistently observed in the postmenopausal or ovarian suppression subgroup across multiple clinical trials, which raises the hypothesis that its greatest anti-tumor effect is in a low estrogen microenvironment. An individual patient data meta-analysis will be required to confirm survival benefit in this setting. This review summarizes the key evidence for current clinical practice and future directions.

Tetra- and hexahydrates of bis(adeninium) zoledronate

The present paper reports the structures of bis(adeninium) zoledronate tetrahydrate {systematic name: bis(6-amino-7H-purin-1-ium) hydrogen [1-hydroxy-2-(1H-imidazol-3-ium-1-yl)-1-phosphonatoethyl]phosphonate tetrahydrate}, 2C5H6N5+·C5H8N2O7P22−·4H2O, (I), and bis(adeninium) zoledronate hexahydrate {systematic name: a 1:1 cocrystal of bis(6-amino-7H-purin-1-ium) hydrogen [1-hydroxy-2-(1H-imidazol-3-ium-1-yl)-1-phosphonatoethyl]phosphonate hexahydrate and 6-amino-7H-purin-1-ium 6-amino-7H-purine dihydrogen [1-hydroxy-2-(1H-imidazol-3-ium-1-yl)ethane-1,1-diyl]diphosphonate hexahydrate}, 2C5H6N5+·C5H8N2O7P22−·6H2O, (II). One of the adenine molecules and one of the phosphonate groups of the zoledronate anion of (II) are protonated on a 50% basis. The zoledronate group displays its usual zwitterionic character, with a protonated imidazole ring; however, the ionization state of the phosphonate groups of the anion for (I) and (II) are different. In (I), the anion has both singly and doubly deprotonated phosphonate groups, while in (II), it has one singly deprotonated phosphonate group and a partially deprotonated phosphonate group. In (I), the cations form anR22(10) base pair, while in (II), they formR22(8) andR22(10) base pairs. Two water molecules in (I) and five water molecules in (II) are involved in water–water interactions. The presence of an additional two water molecules in the structure of (II) might influence the different ionization state of the anion as well as the different packing mode compared to (I).

Role of bisphosphonates in postmenopausal women with breast cancer

Data suggest that bisphosphonates protect bone health and may have anticancer activity in postmenopausal women during adjuvant breast cancer therapy. However, key questions remain surrounding the role of adjuvant bisphosphonates in breast cancer, including patient populations deriving benefit, timing/scheduling of therapy, and specific clinical benefits. PubMed, Embase, and San Antonio Breast Cancer Symposium databases provide study results that address these issues in postmenopausal women. Review of these data would aid physicians in providing optimal management of breast cancer in postmenopausal women. For example, recent data reinforce use of intravenous bisphosphonates concurrently with adjuvant endocrine therapy to ameliorate bone loss in recently postmenopausal or osteopenic postmenopausal women with early breast cancer. In contrast, clinical data for oral bisphosphonates have not provided support for using anti-osteoporosis doses in this setting, and the optimal dose is unclear. Additionally, current clinical data show improvements in disease outcomes with bisphosphonates in many studies, although not in all patient subsets. Strong support for the potential adjuvant anticancer benefits from bisphosphonates has been demonstrated in women with established menopause (i.e., very low circulating estrogen levels). Initiating bisphosphonates early and concomitantly with adjuvant therapy generally provided the greatest benefits. However, questions remain such as schedule of treatment and relative potency among the intravenous bisphosphonates and elucidation of the role of oral bisphosphonates, as well as ongoing studies that might provide clarification. This review addresses these controversies in the context of translational research, which may provide the rationale for ongoing studies and evolving treatment paradigms in this area.

Zoledronic acid: monoclinic and triclinic polymorphs from powder diffraction data

The crystal structures of the monoclinic and triclinic polymorphs of zoledronic acid, C5H10N2O7P2, have been established from laboratory powder X-ray diffraction data. The molecules in both polymorphs are described as zwitterions, namely 1-(2-hydroxy-2-phosphonato-2-phosphonoethyl)-1H-imidazol-3-ium. Strong intermolecular hydrogen bonds (with donor–acceptor distances of 2.60 Å or less) link the molecules into layers, parallel to the (100) plane in the monoclinic polymorph and to the (1\overline{1}0) plane in the triclinic polymorph. The phosphonic acid groups form the inner side of each layer, while the imidazolium groups lie to the outside of the layer, protruding in opposite directions. In both polymorphs, layers related by translation along [100] interact through weak hydrogen bonds (with donor–acceptor distances greater than 2.70 Å), forming three-dimensional layered structures. In the monoclinic polymorph, there are hydrogen-bonded centrosymmetric dimers linked by four strong O—H...O hydrogen bonds, which are not present in the triclinic polymorph.

Protection of bone in premenopausal women with breast cancer: focus on zoledronic acid

Maintaining bone health is important for patients with breast cancer (BC), the most commonly diagnosed cancer in American women. Indeed, bone loss is common throughout the BC disease continuum. In the metastatic BC setting, patients are likely to develop bone metastases, a painful complication that can lead to potentially debilitating skeletal-related events. Bone health is equally important for patients with early BC. During adjuvant therapy for early BC, the largest challenge to bone health is from accelerated bone mineral density (BMD) loss. Although decreased BMD is well recognized in older, postmenopausal women, it may be underestimated in younger, premenopausal women undergoing endocrine therapy for BC. The rate and extent of cancer therapy-induced bone loss (from chemotherapy or endocrine therapy) are substantially greater than normal decreases in BMD during menopause. Bisphosphonates such as zoledronic acid (ZOL) are antiresorptive agents indicated for the treatment of bone metastases from BC. Clinical trials over the past few years suggest that, although not yet approved for this indication, ZOL can prevent cancer therapy-induced bone loss and improve BMD in premenopausal women receiving adjuvant (endocrine or chemo-) therapy for BC. Furthermore, the benefits of ZOL therapy may go beyond maintaining bone health and include potential anticancer benefits together with favorable tolerability and cost/benefit profiles. This review will focus specifically on the role of ZOL in preserving the bone health of premenopausal women with BC.