Usefulness of Bone Formation Markers in Breast Cancer

A Phase II Trial of Cabozantinib in Hormone Receptor-Positive Breast Cancer with Bone Metastases

BACKGROUND

We assessed the antitumor activity of cabozantinib, a potent multireceptor oral tyrosine kinase inhibitor, in patients with hormone receptor-positive breast cancer with bone metastases.

PATIENTS AND METHODS

In this single-arm multicenter phase II study, patients received an initial starting dose of 100 mg, later reduced to 60 mg, per day. The primary endpoint was the bone scan response rate. Secondary endpoints included objective response rate by RECIST, progression-free survival (PFS), and overall survival (OS).

RESULTS

Of 52 women enrolled, 20 (38%) experienced a partial response on bone scan and 6 (12%) had stable disease. Prior to the first repeat bone scan at 12 weeks, 19 (35%) patients discontinued study treatment because of early clinical progression or unacceptable toxicity. RECIST evaluation based on best overall response by computed tomography revealed stable disease in extraosseous tissues in 26 patients (50%) but no complete or partial responses. In 25 patients with disease control on bone scan at 12 weeks, only 3 (12%) patients developed extraosseous progression. The median PFS was 4.3 months, and median OS was 19.6 months. The most common grade 3 or 4 toxicities were hypertension (10%), anorexia (6%), diarrhea (6%), fatigue (4%), and hypophosphatemia (4%).

CONCLUSION

Bone scans improved in 38% of patients with metastatic hormone receptor-positive breast cancer and remained stable in an additional 12% for a minimum duration of 12 weeks on cabozantinib. Further investigations should assess the activity of cabozantinib in combination with other hormonal and other breast cancer therapies and determine whether bone scan responses correlate with meaningful antitumor effects. ClinicalTrials.gov identifier. NCT01441947 IMPLICATIONS FOR PRACTICE: Most patients with metastatic hormone receptor-positive (HR+) breast cancer have bone involvement, and many have bone-only disease, which is difficult to evaluate for response. This phase II single-arm study evaluated the clinical activity of the small molecule MET/RET/VEGFR2 inhibitor cabozantinib in patients with metastatic HR+ breast cancer with bone metastases. This study met its primary endpoint, and cabozantinib treatment resulted in a significant bone scan response rate correlating with improved survival. This is the first study to use bone scan response as a primary endpoint in breast cancer. The results support further study of cabozantinib in HR+ breast cancer.

Bone turnover markers in serum and urine as diagnostic, prognostic and monitoring biomarkers of bone metastasis

Bone metastases are characterized by increased osteoblastic and/or osteolytic processes depending on the tumor type. The altogether destructive effect of metastasis formation promoted by increased metabolic activity raises the release of components from the osseous metabolism into the blood stream. These components are either enzymes directly involved in the alteration processes, metabolites/proteins that develop during this or bone matrix proteins released during this. These biomarkers are categorized in relation to their involvement in the bone formation or resorption as bone formation and resorption markers. Based on a PubMed literature search, a critical appraisal of the various biomarkers for diagnostic, prognostic, and monitoring purposes is given for patients with skeletal metastases caused by breast, prostate, lung, or renal cell carcinomas.

Carcinoma-associated fibroblasts provide operational flexibility in metastasis

Malignant cancer cells do not act as lone wolves to achieve metastasis, as they exist within a complex ecosystem consisting of an extracellular matrix scaffold populated by carcinoma-associated fibroblasts (CAFs), endothelial cells and immune cells. We recognize local (primary tumor) and distant ecosystems (metastasis). CAFs, also termed myofibroblasts, may have other functions in the primary tumor versus the metastasis. Cellular origin and tumor heterogeneity lead to the expression of specific markers. The molecular characteristics of a CAF remain in evolution since CAFs show operational flexibility. CAFs respond dynamically to a cancer cell's fluctuating demands by shifting profitable signals necessary in metastasis. Local, tissue-resident fibroblasts and mesenchymal stem cells (MSCs) coming from reservoir sites such as bone marrow and adipose tissue are the main progenitor cells of CAFs. CAFs may induce awakening from metastatic dormancy, a major cause of cancer-specific death. Cancer management protocols influence CAF precursor recruitment and CAF activation. Since CAF signatures represent early changes in metastasis, including formation of pre-metastatic niches, we discuss whether liquid biopsies, including exosomes, may detect and monitor CAF reactions allowing optimized prognosis of cancer patients.

Denosumab for the treatment of bone metastases in advanced breast cancer

In women with advanced breast cancer, approximately three-quarters develop metastases to the bone, with a median survival after diagnosis of 2-3 years. Receptor activator of nuclear factor-κB (RANK) and RANK ligand (RANKL) belong to a signal pathway highly implicated in the development of bone metastases. Denosumab, a human monoclonal antibody with high affinity and specificity for RANKL, prevents the RANKL/RANK interaction and inhibits osteoclast formation and function, thereby decreasing bone resorption and increasing bone mass. Denosumab compared with zoledronic acid showed superior efficacy in delaying time to first-on study SRE and time to first- and subsequent-on study SREs as well as reduction in bone turnover markers. These results led to the approval of denosumab by the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA), for the prevention of SREs in adults with bone metastases from solid tumors, including breast cancer.

Consensus on the utility of bone markers in the malignant bone disease setting

Biochemical markers of bone turnover provide insight into ongoing rates of skeletal metabolism and tumor-bone interactions in patients with malignant bone disease. This article reviews the available recent evidence assessing the potential of bone markers for detecting and monitoring malignant bone lesions in patients with advanced cancers, and for assessing overall skeletal health and response to antiresorptive therapies in patients at all stages of cancer progression. Most data thus far are for urinary N-terminal cross-linked telopeptide of type I collagen (NTX) in predicting risks of skeletal morbidity and death and monitoring response to zoledronic acid in patients with bone metastases. Ongoing studies are evaluating such correlations for other markers and therapies. Emerging evidence suggests that bone markers may help identify patients at high risk for bone metastasis or bone lesion progression, thereby allowing improved follow-up. Results from ongoing clinical trials evaluating such potential applications of bone markers are awaited.

Lectin affinity electrophoresis of serum alkaline phosphatase in metastasized breast cancer

The use of serum alkaline phosphatase (ALP) isoenzymes as markers of breast cancer metastases and treatment efficacy has received little attention. Twenty-six breast cancer women (56+/-13 years, all post-menopausal) were prospectively evaluated during their first and third course of chemotherapy (4-week interval). Serum samples were analyzed for ALP isoenzymes (bone, liver, and intestine) using a lectin affinity electrophoresis kit (Hydragel 15 ISO-PAL, Sebia) adapted on a semi-automated Hydrasys system (Sebia). Results were compared with imaging techniques for the presence of metastases; bone ALP isoenzyme (B-ALP) results were compared with C-Terminal degradation products of type I collagen (S-CTX) (CrossLaps, IDS Nordic). Serum B-ALP, but not S-CTX, confirmed the presence of bone metastases (BM) (n=15) with 67/100% sensitivity/specificity (using a 69 UI/L ROC cut-off); ROC AUC was 0.806 (P=0.0004) (NS for S-CTX). Chemotherapy reduced serum B-ALP by 24% over 4 weeks (P=0.0012); there was no change for S-CTX. There was no specific clinical pattern for other ALP isoenzymes (liver and intestine). In conclusion, serum B-ALP, but not S-CTX, could help confirm the presence of BM in breast cancer patients.

Metastatic bone pain: treatment options with an emphasis on bisphosphonates

INTRODUCTION

One of the key targets for metastatic cancer cells is the skeleton. Once metastatic cells are established within the bone matrix, skeletal integrity becomes increasingly compromised. Bone lesions lead to various complications, including bone pain, fractures and spinal cord compression.

MECHANISMS OF BONE PAIN

Bone pain is debilitating and affects quality of life of the patient. In addition, it increases the use of health care resources. Many patients with metastatic bone disease experience substantial bone pain despite state-of-the-art systemic analgesic treatment. Incident pain is the predominant pain syndrome.

TREATMENT OPTIONS FOR BONE PAIN

Typically, this syndrome requires moderate baseline analgesia with increased on-demand doses. Other techniques for treating bone pain, including radiation therapy, neuraxial application of analgesics, nerve blocks and local stabilisation procedures, should be considered. In addition, therapy with bisphosphonates targeting bone-specific pain is an important strategy. This review discusses the various management options for bone pain arising from metastatic bone disease.

Phase 1 trial of denosumab safety, pharmacokinetics, and pharmacodynamics in Japanese women with breast cancer-related bone metastases

Denosumab, a fully human monoclonal antibody to receptor activator of nuclear factor-kappa B ligand (RANKL), suppresses bone resorption. This open-label, multicenter, phase 1 study evaluated the safety, pharmacodynamics, and pharmacokinetics of denosumab in Japanese women with breast cancer-related bone metastases. Patients (n = 18; median age, 57 years) received a single subcutaneous injection of denosumab 60 mg or 180 mg or three doses of denosumab 180 mg on days 1, 29, and 57 (every 4 weeks) and were followed for > or = 141 days. No major safety concerns related to denosumab were noted in any cohort. All patients experienced at least 1 adverse event (AE); most were mild (grade < or = 2). One patient reported grade 4 myositis and grade 3 anemia, malaise, and dysphagia that the investigator deemed treatment-related; other treatment-related AE were grade < or = 2. No antidenosumab antibodies or clinically significant changes in laboratory findings, vital signs, or electrocardiograms were observed. Pharmacokinetics were approximately dose-linear. Denosumab caused rapid, substantial, and sustained suppression of urinary N-telopeptide corrected for creatinine (uNTx/Cr) across all doses; at day 85, the median change from baseline uNTx/Cr ranged from -61.9% to -90.8%. No dose-limiting toxicity was observed at any dosage. Coupled with pharmacokinetic and pharmacodynamic data, these results were consistent with those observed in non-Japanese populations.

BGLAP is expressed in pancreatic cancer cells and increases their growth and invasion

Background

Bone gamma-carboxyglutamate protein (BGLAP; osteocalcin) is a small, highly conserved molecule first identified in the mineralized matrix of bone. It has been implicated in the pathophysiology of various malignancies. In this study, we analyzed the expression and role of BGLAP in the normal human pancreas, chronic pancreatitis (CP), and pancreatic ductal adenocarcinoma (PDAC) using quantitative RT-PCR, immunohistochemistry, immunocytochemistry and enzyme immunoassays, as well as cell proliferation and invasion assays. Gene silencing was carried out using specific siRNA molecules.

Results

Compared to the normal pancreas, BGLAP mRNA and protein levels were not significantly different in CP and PDAC tissues. BGLAP was faintly present in the cytoplasm of normal acinar cells but was strongly expressed in the cytoplasm and nuclei of tubular complexes and PanIN lesions of CP and PDAC tissues. Furthermore, BGLAP expression was found in the cancer cells in PDAC tissues as well as in 4 cultured pancreatic cancer cell lines. TNFalpha reduced BGLAP mRNA and protein expression levels in pancreatic cancer cell lines. In addition, BGLAP silencing led to reduction of both cell growth and invasion in those cells.

Conclusion

BGLAP is expressed in pancreatic cancer cells, where it potentially increases pancreatic cancer cell growth and invasion through autocrine and/or paracrine mechanisms.

Predictive value of osteocalcin and β-CrossLaps in metastatic breast cancer

OBJECTIVES

Assessment of the diagnostic value of serum CEA, CA 15.3, osteocalcin (OC) and beta-CrossLaps (beta-CTX) in the detection of metastatic breast cancer.

DESIGN AND METHODS

This study included 47 patients with breast cancer (20 non-metastatic breast cancer, 11 bone metastasis, 11 soft tissue metastasis, 5 bone plus soft tissue metastasis), 10 patients with benign breast lesions and 13 healthy volunteers. CEA and CA 15.3 were determined using microparticle enzyme immunoassay; while OC and beta-CTX were measured by electrochemiluminescence immunoassay.

RESULTS

CEA, CA 15.3, OC and beta-CTX median levels were higher in breast cancer patients compared to controls (p=0.006, 0.001, 0.004 and 0.038, respectively). Increased levels of OC and beta-CTX were demonstrated in bone metastatic patients compared to non-metastatic or soft tissue metastatic patients (p=0.000).

CONCLUSIONS

Combined use of OC and beta-CTX could be useful in early detection of bone metastatic breast cancer which might improve the outcome of the disease.

Randomized active-controlled phase II study of denosumab efficacy and safety in patients with breast cancer-related bone metastases

PURPOSE

Denosumab, a fully human monoclonal antibody to receptor activator of nuclear factor-kappaB ligand, suppresses bone resorption. In this study, we evaluated the efficacy and safety of five dosing regimens of denosumab in patients with breast cancer-related bone metastases not previously treated with intravenous bisphosphonates (IV BPs).

PATIENTS AND METHODS

Eligible women (n = 255) with breast cancer-related bone metastases were stratified by type of antineoplastic therapy received and randomly assigned to one of six cohorts (five denosumab cohorts [blinded to dose and frequency]; one open-label IV BP cohort). Denosumab was administered subcutaneously every 4 weeks (30, 120, or 180 mg) or every 12 weeks (60 or 180 mg). The primary end point was percentage of change in the bone turnover marker urine N-telopeptide corrected for urine creatinine (uNTx/Cr) from baseline to study week 13. The percentage of patients achieving more than 65% uNTx/Cr reduction, time to more than 65% uNTx/Cr reduction, patients experiencing one or more on-study skeletal-related events (SRE), and safety were also evaluated.

RESULTS

At study week 13, the median percent reduction in uNTx/Cr was 71% for the pooled denosumab groups and 79% for the IV BP group. Overall, 74% of denosumab-treated patients (157 of 211) achieved a more than 65% reduction in uNTx/Cr compared with 63% of bisphosphonate-treated patients (27 of 43). On-study SREs were experienced by 9% of denosumab-treated patients (20 of 211) versus 16% of bisphosphonate-treated patients (seven of 43). No serious or fatal adverse events related to denosumab occurred.

CONCLUSION

Subcutaneous denosumab may be similar to IV BPs in suppressing bone turnover and reducing SRE risk. The safety profile was consistent with an advanced breast cancer population receiving systemic therapy.