Brain Metastases in Patients with Breast Cancer: New Horizons

SKOR1 mediates FER kinase-dependent invasive growth of breast cancer cells

High expression of the non-receptor tyrosine kinase FER is an independent prognostic factor that correlates with poor survival in breast cancer patients. To investigate whether the kinase activity of FER is essential for its oncogenic properties, we developed an ATP analogue-sensitive knock-in allele (FERASKI). Specific FER kinase inhibition in MDA-MB-231 cells reduces migration and invasion, as well as metastasis when xenografted into a mouse model of breast cancer. Using the FERASKI system, we identified Ski family transcriptional corepressor 1 (SKOR1) as a direct FER kinase substrate. SKOR1 loss phenocopies FER inhibition, leading to impaired proliferation, migration and invasion, and inhibition of breast cancer growth and metastasis formation in mice. We show that SKOR1 Y234, a candidate FER phosphorylation site, is essential for FER-dependent tumor progression. Finally, our work suggests that the SKOR1 Y234 residue promotes Smad2/3 signaling through SKOR1 binding to Smad3. Our study thus identifies SKOR1 as a mediator of FER-dependent progression of high-risk breast cancers.

Evaluation of Prognostic Factors that Affect Survival Outcomes of Breast Cancer Patients with Brain Metastases: A Single Institutional Experience

Objective

This study aimed to evaluate various prognostic factors that play a vital role in stratifying and guiding tailored treatment strategies and survival outcome in breast cancer patients with brain metastases (BM).

Materials and Methods

Data regarding demography, clinical presentation, molecular subtypes, risk-stratification, treatment details, and outcomes were retrieved from medical records. All time-to-event (survival) outcomes were analyzed by Kaplan-Meir method and compared using log-rank test. Univariate and multivariate analysis of relevant prognostic factors were performed and p-values ≤0.05 were considered statistically significant.

Results

A total of 88 patients (median age: 50 years) were included for this study. The median follow-up time of all surviving patients was ~20 months. During the follow-up, 82 (93.1%) patients died. The median survival of all patients was 12 months, with 1-year and 2-year overall survival (OS) rate of 51% and 22%, respectively. Based on univariate analysis, statistically significant prognostic factors for OS were molecular subtypes, number of BM, and Karnofsky Performance Status (KPS); however, number of BM and KPS emerged as independent predictors of survival based on multivariate analysis.

Conclusion

We conclude that, there are other important prognostic factor, such as number of BM, which may affect the OS of these patients, in addition to variables included in the diagnosis-specific graded prognostic assessment score. Prospective studies evaluating these factors are necessary to further refine the stratification of patients, which will aid the initiation of appropriate treatment to improve the OS of patients.

Actein Inhibits Tumor Growth and Metastasis in HER2-Positive Breast Tumor Bearing Mice via Suppressing AKT/mTOR and Ras/Raf/MAPK Signaling Pathways

HER2-positive breast cancer accounts for 15–20% in breast cancer and 50% of the metastatic HER2-positive breast cancer patients died of central nervous system progression. The present study investigated the effects of actein (a natural cycloartane triterpene) on cells adhesion, migration, proliferation and matrix degradation, and its underlying mechanism in HER2-positive breast cancer cells. The in vivo effect of actein on tumor growth and metastasis in MDA-MB-361 tumor-bearing mice as well as the anti-brain metastasis in tail vein injection mice model were also investigated. Our results showed that actein inhibited HER2-positive breast cancer cells viability, proliferation and migration. Actein also induced MDA-MB-361 cells G1 phase arrest and inhibited the expressions of cyclins and cyclin-dependent kinases. For intracellular mechanisms, actein inhibited the expressions of molecules in AKT/mTOR and Ras/Raf/MAPK signaling pathways. Furthermore, actein (15 mg/kg) was shown to exhibit anti-tumor and anti-metastatic activities in MDA-MB-361 breast tumor-bearing mice, and reduced brain metastasis in tail vein injection mice model. All these findings strongly suggested that actein is a potential anti-metastatic agent for HER2-positive breast cancer.

Novel Breast Cancer Brain Metastasis Patient-Derived Orthotopic Xenograft Model for Preclinical Studies

The vast majority of mortality in breast cancer results from distant metastasis. Brain metastases occur in as many as 30% of patients with advanced breast cancer, and the 1-year survival rate of these patients is around 20%. Pre-clinical animal models that reliably reflect the biology of breast cancer brain metastasis are needed to develop and test new treatments for this deadly condition. The patient-derived xenograft (PDX) model maintains many features of a donor tumor, such as intra-tumor heterogeneity, and permits the testing of individualized treatments. However, the establishment of orthotopic PDXs of brain metastasis is procedurally difficult. We have developed a method for generating such PDXs with high tumor engraftment and growth rates. Here, we describe this method and identify variables that affect its outcomes. We also compare the brain-orthotopic PDXs with ectopic PDXs grown in mammary pads of mice, and show that the responsiveness of PDXs to chemotherapeutic reagents can be dramatically affected by the site that they are in.

Analysis of survival outcomes based on molecular subtypes in breast cancer brain metastases: A single institutional cohort

PURPOSE

To evaluate the survival outcomes based on molecular subtypes of breast cancer in patients with brain metastasis.

MATERIALS AND METHODS

We retrospectively reviewed 106 breast cancer patients treated for brain metastases, from January 2005 to May 2016. Patients were divided into four groups based on the tumor molecular subtype: luminal A (Estrogen Receptor [ER]/Progesterone Receptor [PR] positive, human epithelial growth factor receptor-2 [HER2] negative), luminal B (ER/PR positive, HER2 Positive), HER2 (HER2 positive and ER/PR negative), and Triple negative (TNBC).

RESULTS

The median follow-up time for surviving patients was 22 months (range: 11.2-51.1 months). The median survival of all patients was 14 months, with a 1-year overall survival (OS) rate of 57.5% and a 2-year OS rate of 32.1%. Thirty patients (28.3%) had a solitary brain metastasis while 62 (58.5%) patients had multiple metastases. A significant difference was observed in the survival rates of the two groups. Based on the Karnofsky performance score, the performance status of the patients at the time of brain metastasis was also found to affect survival. Patients with different molecular subtypes had different survival rates; the luminal A group showed the highest median survival (luminal A: 23.1, luminal B: 15.0, HER2: 12.5 and TNBC: 6.4 months, respectively), which was statistically significant.

CONCLUSION

In breast cancer patients with brain metastasis, survival rates were different based on the molecular subtype of the tumor, despite various local and systemic treatments. Appropriate and tailored treatment approaches should, therefore, be considered for the different molecular subtypes.

Single institution validation of a modified graded prognostic assessment of patients with breast cancer brain metastases

Aim:

The number of breast cancer brain metastases is a prognostic clinical variable in the modified graded prognostic assessment (GPA) Index for breast cancer.

Patients & methods:

We retrospectively gathered data from 127 breast cancer patients who underwent radiation therapy for brain metastasis. Patients were stratified by both breast GPA and modified breast GPA scores, and survival was determined using the Kaplan–Meier curves and Cox proportional hazards model.

Results & Conclusion:

The Kaplan–Meier curve for patients under the breast GPA classification were not significant, but were significant under the modified breast GPA classification. The inclusion of number of brain metastases into the modified breast GPA index improved prognosis, thus validating the use of the modified breast GPA in prognosticating patient outcome.

When Should Trastuzumab be Stopped after Achieving Complete Response in Her2-Positive Metastatic Breast Cancer Patients?

We report the case of a woman with HER2-positive metastatic breast cancer who achieved prolonged complete remission of multiple liver metastases after treatment with weekly trastuzumab plus paclitaxel but relapsed in the brain soon after stopping trastuzumab maintenance therapy which had been prosecuted for almost three years. In the absence of randomized trials, the optimal duration of trastuzumab administration after achieving complete remission of metastatic breast cancer remains questionable.

JAK2-binding long noncoding RNA promotes breast cancer brain metastasis

Conventional therapies for breast cancer brain metastases (BCBMs) have been largely ineffective because of chemoresistance and impermeability of the blood-brain barrier. A comprehensive understanding of the underlying mechanism that allows breast cancer cells to infiltrate the brain is necessary to circumvent treatment resistance of BCBMs. Here, we determined that expression of a long noncoding RNA (lncRNA) that we have named lncRNA associated with BCBM (Lnc-BM) is prognostic of the progression of brain metastasis in breast cancer patients. In preclinical murine models, elevated Lnc-BM expression drove BCBM, while depletion of Lnc-BM with nanoparticle-encapsulated siRNAs effectively treated BCBM. Lnc-BM increased JAK2 kinase activity to mediate oncostatin M- and IL-6-triggered STAT3 phosphorylation. In breast cancer cells, Lnc-BM promoted STAT3-dependent expression of ICAM1 and CCL2, which mediated vascular co-option and recruitment of macrophages in the brain, respectively. Recruited macrophages in turn produced oncostatin M and IL-6, thereby further activating the Lnc-BM/JAK2/STAT3 pathway and enhancing BCBM. Collectively, our results show that Lnc-BM and JAK2 promote BCBMs by mediating communication between breast cancer cells and the brain microenvironment. Moreover, these results suggest targeting Lnc-BM as a potential strategy for fighting this difficult disease.

A Multidisciplinary Breast Cancer Brain Metastases Clinic: The University of North Carolina Experience

The University of North Carolina at Chapel Hill has created a clinic to provide medical and radiation oncology, neurosurgical, and supportive services to patients with breast cancer brain metastases. Of the 65 patients seen between January 2012 and January 2015, 78% returned for a follow-up visit and 32% were enrolled in a clinical trial. The clinic is a model that can be adapted at other centers.

Background.

Breast cancer brain metastasis (BCBM) confers a poor prognosis and is unusual in requiring multidisciplinary care in the metastatic setting. The University of North Carolina at Chapel Hill (UNC-CH) has created a BCBM clinic to provide medical and radiation oncology, neurosurgical, and supportive services to this complex patient population. We describe organization and design of the clinic as well as characteristics, treatments, and outcomes of the patients seen in its first 3 years.

Methods.

Clinical and demographic data were collected from patients in a prospectively maintained database. Descriptive statistics are reported as percentages and means. The Kaplan-Meier method was used to estimate time-to-event outcomes.

Results.

Sixty-five patients were seen between January 2012 and January 2015. At the time of presentation to the BCBM clinic, most patients (74%) had multiple (≥2) brain metastases and had received prior systemic (77%) and whole-brain radiation therapy and/or central nervous system stereotactic radiosurgery (65%) in the metastatic setting. Seventy-eight percent returned for a follow-up visit; 32% were enrolled in a clinical trial. Median time from diagnosis of brain metastasis to death was 2.11 years (95% confidence interval [CI] 1.31–2.47) for all patients, 1.15 years (95% CI 0.4–2.43) for triple-negative breast cancer, 1.31 years (95% CI 0.51–2.52) for hormone receptor-positive/HER2− breast cancer, and 3.03 years (95% CI lower limit 1.94, upper limit not estimable) for HER2+ breast cancer (p = .0037).

Conclusion.

Patients with BCBM have unique and complex needs that require input from several oncologic disciplines. The development of the UNC-CH multidisciplinary BCBM clinic is a model that can be adapted at other centers to provide coordinated care for patients with a challenging and complex disease.

Implications for Practice:

Patients with breast cancer brain metastases often require unique multidisciplinary care to meet the numerous and uncommon challenges associated with their conditions. Here, the development and characteristics of a clinic designed specifically to provide for the multidisciplinary needs of patients with breast cancer brain metastases are described. This clinic may serve as a model for other institutions interested in creating specialty clinics with similar objectives.

Brain metastases from breast cancer: lessons from experimental magnetic resonance imaging studies and clinical implications

Breast cancer that has metastasized to the brain presents difficult clinical challenges. This diagnosis comes with high mortality rates, largely due to complexities in early detection and ineffective therapies associated with both dormancy and impermeability of the blood-brain barrier (BBB). Magnetic resonance imaging (MRI) is the current gold standard for diagnosis and assessment of brain tumors. It has been used clinically to investigate metastatic development as well as monitor response to therapy. Here, we describe preclinical imaging strategies that we have used to study the development of brain metastases due to breast cancer. Using this approach, we have identified three subsets of metastatic disease: permeable metastases, nonpermeable metastases, and solitary, dormant cancer cells, which likely have very different biology and responses to therapy. The ability to simultaneously monitor the spatial and temporal distribution of dormant cancer cells, metastatic growth, and associated tumor permeability can provide great insight into factors that contribute to malignant proliferation. Our preclinical findings suggest that standard clinical detection strategies may underestimate the true metastatic burden of breast cancer that has metastasized to the brain. A better understanding of true metastatic burden in brains will be important to assist in the development of more effective chemotherapeutics-particularly those targeted to cross the BBB-as well as detection of small nonpermeable metastases.

Hormone receptor expression is associated with a unique pattern of metastatic spread and increased survival among HER2-overexpressing breast cancer patients

OBJECTIVES

HER2/neu (HER2) overexpression occurs in approximately 20% of breast cancers and is associated with aggressive disease. Although a significant number of HER2-positive tumors also express hormone receptors (HR), the effects HR expression has on clinical characteristics, including response to trastuzumab among HER2-positive breast cancer, has not been elucidated yet.

METHODS

A retrospective analysis of consecutive metastatic HER2-positive breast cancer patients was conducted in 2 medical centers. Associations between hormone receptors expression and clinical variables, and metastatic spread pattern and survival were studied.

RESULTS

The study population included 137 metastatic HER2-positive breast cancer patients, 56 of them were HR-positive and 81 were HR-negative. No significant differences between the 2 groups were found for demographic and clinical characteristics, including age, stage at diagnosis, tumor histology, and grade. Similar response rate to trastuzumab was observed in both study groups. Significantly, longer, median, disease-free, and overall survival was noted among the HR-positive patients. Patients in the HR-negative group had significantly more liver metastases, a trend for more brain metastases, and less bone metastases. There was a strong trend for more visceral metastases in the HR-negative group.

CONCLUSIONS

Our results suggest an important role for HR expression in modulating metastases predilection and disease progression in HER2-positive breast cancer.

A systematic review of trastuzumab and lapatinib in the treatment of women with brain metastases from HER2-positive breast cancer

Patients with HER2-positive breast cancer are living still longer and increasingly experiencing brain metastases. Current HER2-targeted therapies have limited potential to cross the blood-brain-barrier. We performed a systematic review to investigate data on HER2-targeting therapies in the treatment of brain metastases in breast cancer. We searched PUBMED for all human studies published 1998-2012 using the following search terms: breast neoplasm/cancer, human epidermal growth factor receptor 2/HER2, ErbB2, trastuzumab, lapatinib, brain/cerebral neoplasm/metastases and blood-brain barrier. We identified few and mostly small clinical studies. Study designs were very heterogeneous making comparisons on endpoints difficult. Overall survival for patients treated with trastuzumab varied from 8 to 25 months and 5.5 to 11 months for patients receiving lapatinib. The majority of studies were retrospective thus possibly biasing data. Only three studies were identified comparing trastuzumab to lapatinib. Conclusively, no solid data exist on how to treat patients with HER2-positive disease and brain metastases. Although continuous HER2-blockade is recommended by international consensus guidelines, it is still not evident which HER2-targeting agent should be preferred when brain metastases occur. The choice of chemotherapy to accompany the blockade is not obvious and we do not know if dual is better than single blockade. Further clinical trials are urgently needed.

Neurotrophin-3 modulates breast cancer cells and the microenvironment to promote the growth of breast cancer brain metastasis

Metastasis, which remains incompletely characterized at the molecular and biochemical levels, is a highly specific process. Despite the ability of disseminated cancer cells to intravasate into distant tissues, it has been long recognized that only a limited subset of target organs develop clinically overt metastases. Therefore, subsequent adaptation of disseminated cancer cells to foreign tissue microenvironment determines the metastatic latency and tissue tropism of these cells. As a result, studying interactions between the disseminated cancer cells and the adjacent stromal cells will provide a better understanding of what constitutes a favorable or unfavorable microenvironment for disseminated cancer cells in a tissue-specific manner. Previously, we reported a protein signature of brain metastasis showing increased ability of brain metastatic breast cancer cells to counteract oxidative stress. In this study, we showed that another protein from the brain metastatic protein signature, neurotrophin-3 (NT-3), has a dual function of regulating the metastatic growth of metastatic breast cancer cells and reducing the activation of immune response in the brain. More importantly, increased NT-3 secretion in metastatic breast cancer cells results in a reversion of mesenchymal-like (EMT) state to epithelial-like (MET) state and vice versa. Ectopic expression of NT-3 in EMT-like breast cancer cells reduces their migratory ability and increases the expression of HER2 (human epidermal growth factor receptor 2) and E-cadherin at the cell-cell junction. In addition, both endogenous and ectopic expression of NT-3 reduced the number of fully activated cytotoxic microglia. In summary, NT-3 appears to promote growth of metastatic breast cancer cells in the brain by facilitating the re-epithelialization of metastatic breast cancer cells and downmodulating the cytotoxic response of microglia. Most importantly, our results provide new insights into the latency and development of central nervous system macrometastases in patients with HER2-positive breast tumors and provide mechanistic rationale to target HER2 signaling for HER2-positive breast cancer brain metastasis.

Treatment of Metastatic Breast Cancer in Women Aged 65 Years and Older

Breast cancer is a disease of aging and the incidence of breast cancer increases dramatically with increasing age. In spite of major advances in prevention, screening and treatment approximately 40,000 Americans still die of metastatic breast cancer every year – the majority being women aged 65 years and older. Metastatic breast cancer remains incurable regardless of age and the goals of treatment are to reduce symptoms when present and to provide the patient with the best quality of life for as long as possible. Cornerstones of treatment to control metastases include endocrine therapy, chemotherapy and radiation therapy. Supportive care that includes psychosocial support and treatment of pain is also a key component of management. This review focuses on the issues related to the care of older women with metastatic breast cancer.

Radiation therapy in the prevention of brain metastases

Over 150,000 cancer patients will be diagnosed with brain metastases this year alone. Survival for those diagnosed with brain metastases remains poor despite multimodality management with surgery, chemotherapy, and radiation. Preventative strategies to mitigate brain metastases have met with mixed results. In leukemia and small cell lung cancer there are defined roles for preventative radiation to be delivered, which can result in improved local control and survival. There is a less defined role for preventative radiation in locally advanced non-small cell lung cancer and budding interest for radiation prevention in breast cancer. The potential impact preventative cranial irradiation may have on neurocognitive function and quality of life needs to be considered prior to its administration.

Phosphatidylinositol 3-kinase pathway activation in breast cancer brain metastases

INTRODUCTION

Activation status of the phosphatidylinositol 3-kinase (PI3K) pathway in breast cancer brain metastases (BCBMs) is largely unknown. We examined expression of phospho(p)-AKT, p-S6, and phosphatase and tensin homologue (PTEN) in BCBMs and their implications for overall survival (OS) and survival after BCBMs. Secondary analyses included PI3K pathway activation status and associations with time to distant recurrence (TTDR) and time to BCBMs. Similar analyses were also conducted among the subset of patients with triple-negative BCBMs.

METHODS

p-AKT, p-S6, and PTEN expression was assessed with immunohistochemistry in 52 BCBMs and 12 matched primary BCs. Subtypes were defined as hormone receptor (HR)+/HER2-, HER2+, and triple-negative (TNBC). Survival analyses were performed by using a Cox model, and survival curves were estimated with the Kaplan-Meier method.

RESULTS

Expression of p-AKT and p-S6 and lack of PTEN (PTEN-) was observed in 75%, 69%, and 25% of BCBMs. Concordance between primary BCs and matched BCBMs was 67% for p-AKT, 58% for p-S6, and 83% for PTEN. PTEN- was more common in TNBC compared with HR+/HER2- and HER2+. Expression of p-AKT, p-S6, and PTEN- was not associated with OS or survival after BCBMs (all, P > 0.06). Interestingly, among all patients, PTEN- correlated with shorter time to distant and brain recurrence. Among patients with TNBC, PTEN- in BCBMs was associated with poorer overall survival.

CONCLUSIONS

The PI3K pathway is active in most BCBMs regardless of subtype. Inhibition of this pathway represents a promising therapeutic strategy for patients with BCBMs, a group of patients with poor prognosis and limited systemic therapeutic options. Although expression of the PI3K pathway did not correlate with OS and survival after BCBM, PTEN- association with time to recurrence and OS (among patients with TNBC) is worthy of further study.

Isolation and characterization of a metastatic hybrid cell line generated by ER negative and ER positive breast cancer cells in mouse bone marrow

Background

The origin and the contribution of breast tumor heterogeneity to its progression are not clear. We investigated the effect of a growing orthotopic tumor formed by an aggressive estrogen receptor (ER)-negative breast cancer cell line on the metastatic potential of a less aggressive ER-positive breast cancer cell line for the elucidation of how the presence of heterogeneous cancer cells might affect each other's metastatic behavior.

Methods

ER positive ZR-75-1/GFP/puro cells, resistant to puromycin and non-tumorigenic/non-metastatic without exogenous estrogen supplementation, were injected intracardiacally into mice bearing growing orthotopic tumors, formed by ER negative MDA-MB-231/GFP/Neo cells resistant to G418. A variant cell line B6, containing both estrogen-dependent and -independent cells, were isolated from GFP expressing cells in the bone marrow and re-inoculated in nude mice to generate an estrogen-independent cell line B6TC.

Results

The presence of ER negative orthotopic tumors resulted in bone metastasis of ZR-75-1 without estrogen supplementation. The newly established B6TC cell line was tumorigenic without estrogen supplementation and resistant to both puromycin and G418 suggesting its origin from the fusion of MDA-MB-231/GFP/Neo and ZR-75-1/GFP/puro in the mouse bone marrow. Compared to parental cells, B6TC cells were more metastatic to lung and bone after intracardiac inoculation. More significantly, B6TC mice also developed brain metastasis, which was not observed in the MDA-MB-231/GFP/Neo cell-inoculated mice. Low expression of ERα and CD24, and high expression of EMT-related markers such as Vimentin, CXCR4, and Integrin-β1 along with high CD44 and ALDH expression indicated stem cell-like characteristics of B6TC. Gene microarray analysis demonstrated a significantly different gene expression profile of B6TC in comparison to those of parental cell lines.

Conclusions

Spontaneous generation of the novel hybrid cell line B6TC, in a metastatic site with stem cell-like properties and propensity to metastasize to brain, suggest that cell fusion can contribute to tumor heterogeneity.

Radiotherapeutic Options for Symptom Control in Breast Cancer

SUMMARY: The majority of breast cancer patients will require radiation therapy at some time during the course of their disease. An estimated 30-50% of all radiation treatments are of palliative nature, either to alleviate symptoms or prophylactic to prevent deterioration of quality of life due to locally progressive disease. Radiotherapy is a locally effective tool, and typically causes no systemic and mostly mild acute side effects. The following article provides an overview of options and decision-making in palliative radiotherapy for symptom control.

Carmustine and methotrexate in combination after whole brain radiation therapy in breast cancer patients presenting with brain metastases: a retrospective study

Background

Since 1999, patients presenting with brain metastases (BM) from breast cancer (BC) are treated in our institution with a carmustine (BCNU) - methotrexate (MTX) combination. We report here our clinical experience regarding this combination.

Patients and Methods

Patients were treated by a combination of BCNU 100 mg/m² on day 1 and MTX 600 mg/m² on day 1 and 15 of a 28 day cycle. Treatment was continued until progression or unacceptable toxicity.

Results

50 patients were treated between 1999 and 2007. 94% of the patients presented with concomitant extra-cerebral disease. Median number of previous metastatic setting chemotherapy regimens was 2 (0-5). Median number of cycles was 3 (1-20). There were 11 objective responses (23% [95%CI 12-37]) among 48 evaluable patients. Median progression-free survival and overall survival (OS) were 4.2 (95%CI: 2.8-5.3) and 6.9 (4.2-10.7) months respectively, with a one-year OS rate of 32% (20-46). Median Relative Dose Intensity for BCNU and MTX were 0.98 (0.31-1.1) and 0.96 (0.57-1.66) respectively. There were 2 presumed treatment-related deaths. One patient developed febrile neutropenia. Performance status, BS-BM score and presence of liver metastases were associated with OS in univariate analysis.

Conclusions

This combination appears to be effective and well tolerated in good performance status BC patients presenting with BM.

Trastuzumab treatment in patients with breast cancer and metastatic CNS disease

BACKGROUND

Patients with metastatic central nervous system (mCNS) disease progression from breast cancer have a poor prognosis and often develop associated neurological complications. Human epidermal growth factor receptor 2 (HER2)-positivity status increases the risk of developing mCNS disease. Trastuzumab is an mAb that targets HER2 and is known to extend survival across all stages of HER2-positive breast cancer.

DESIGN

This review considers evidence from preclinical and clinical studies examining the value of continuing trastuzumab treatment in patients who develop mCNS disease. A wealth of data from clinical studies showed that trastuzumab prolonged survival in patients with mCNS disease, compared with no trastuzumab treatment, by effectively controlling their non-CNS disease. Trastuzumab has also been shown to penetrate an impaired blood-brain barrier to a limited degree, such as during radiotherapy, and intrathecal delivery of trastuzumab to the central nervous system (CNS) has shown promise. Research efforts are focussing on improving the delivery of trastuzumab to the CNS.

CONCLUSION

Evidence indicates that patients with mCNS disease from HER2-positive breast cancer should continue to receive trastuzumab to control HER2-positive metastases outside the CNS and receive established therapies to control the mCNS disease.

The HER-2 receptor and breast cancer: ten years of targeted anti-HER-2 therapy and personalized medicine

The human epidermal growth factor receptor (HER-2) oncogene encodes a transmembrane tyrosine kinase receptor that has evolved as a major classifier of invasive breast cancer and target of therapy for the disease. The validation of the general prognostic significance of HER-2 gene amplification and protein overexpression in the absence of anti-HER-2 targeted therapy is discussed in a study of 107 published studies involving 39,730 patients, which produced an overall HER-2-positive rate of 22.2% and a mean relative risk for overall survival (OS) of 2.74. The issue of HER-2 status in primary versus metastatic breast cancer is considered along with a section on the features of metastatic HER-2-positive disease. The major marketed slide-based HER-2 testing approaches, immunohistochemistry, fluorescence in situ hybridization, and chromogenic in situ hybridization, are presented and contrasted in detail against the background of the published American Society of Clinical Oncology-College of American Pathologists guidelines for HER-2 testing. Testing issues, such as the impact of chromosome 17 polysomy and local versus central HER-2 testing, are also discussed. Emerging novel HER-2 testing techniques, including mRNA-based testing by real-time polymerase chain reaction and DNA microarray methods, HER-2 receptor dimerization, phosphorylated HER-2 receptors, and HER-2 status in circulating tumor cells, are also considered. A series of biomarkers potentially associated with resistance to trastuzumab is discussed with emphasis on the phosphatase and tensin homologue deleted on chromosome ten/Akt and insulin-like growth factor receptor pathways. The efficacy results for the more recently approved small molecule HER-1/HER-2 kinase inhibitor lapatinib are also presented along with a more limited review of markers of resistance for this agent. Additional topics in this section include combinations of both anti-HER-2 targeted therapies together as well as with novel agents including bevacizumab, everolimus, and tenespimycin. A series of novel HER-2-targeting agents is also presented, including pertuzumab, ertumaxomab, HER-2 vaccines, and recently discovered tyrosine kinase inhibitors. Biomarkers predictive of HER-2 targeted therapy toxicity are included, and the review concludes with a consideration of HER-2 status in the prediction of response to non-HER-2 targeted treatments including hormonal therapy, anthracyclines, and taxanes.

Prophylactic cranial irradiation in advanced breast cancer: a case for caution

PURPOSE

Prophylactic cranial irradiation (PCI) has a well-recognized role in the treatment of leukemia and small-cell lung cancer. Clinical utility has yet to be determined for breast cancer, where an emerging group at high risk of brain metastasis has fuelled consideration of PCI.

METHODS AND MATERIALS

In reviewing our experience with PCI as part of a complex protocol for advanced breast cancer, we present descriptive data on late central nervous system outcomes in those receiving PCI. After high-dose anthracycline-based induction chemotherapy, Stage IIIB/IV breast cancer responders underwent tandem autologous marrow transplantation. Those in continued remission were referred for PCI. Whole-brain radiotherapy was delivered by usual means, at 36 Gy in 20 fractions.

RESULTS

Twenty-four women, with median age 45 (28-61), were enrolled between 1995 and 1998. Disease was largely metastatic (79%), and 75% were previously exposed to chemotherapy or hormonotherapy. Ten patients received PCI, at a median of 13.4 (11.8-16.5) months from study entry. Six patients developed brain metastases, 2 despite PCI. Striking functional decline was documented in 3 patients (at 9 months, 4 years, and 5 years post-PCI), including one previously high-functioning woman requiring full care for posttreatment dementia.

CONCLUSIONS

We present a series of advanced breast cancer patients treated prophylactically with whole-brain radiotherapy following an aggressive chemotherapy regimen. Although the therapeutic benefit of PCI is not ascertainable here, we describe brain metastases occurring despite PCI and serious long-term neurobehavioral sequelae in PCI-treated patients. Any further investigation of PCI in high-risk breast cancer will need to be approached with caution.

Central nervous system metastases in HER-2 positive metastatic breast cancer patients treated with trastuzumab: incidence, survival, and risk factors

BACKGROUND

A higher incidence of central nervous system (CNS) metastases in HER-2-positive metastatic breast cancer (MBC) has recently been reported.

MATERIALS AND METHODS

Aims of this observational study were to evaluate the incidence of CNS metastases in HER-2-positive MBC patients, to define the outcome of patients with CNS metastases, and to identify the risk factors for CNS relapse.

RESULTS

Between April 1999 and June 2005 we treated 122 consecutive HER-2-positive MBC patients with chemotherapy and trastuzumab. At a median follow-up of 28 months from the occurrence of metastatic disease, 43 patients (35.2%) developed CNS metastases. The median time to death from the diagnosis of CNS metastases was 23.46 months. At multivariate analysis we found that only premenopausal status at diagnosis of breast cancer and visceral metastases as the dominant site at relapse were significantly associated with a higher risk for CNS metastases.

CONCLUSION

The CNS metastasis incidence is very high in HER-2-positive MBC, but the survival after CNS relapse in these patients is longer than in patients unselected for HER-2 status, because of the better control of extracranial disease obtained by trastuzumab. The identified risk factors for CNS relapse could allow us to select a subgroup of HER-2-positive MBC patients as candidates for active surveillance for CNS progression (by computed tomography or magnetic resonance imaging) and/or as candidates for accrual in trials of prevention of CNS relapse.

Adaptation of energy metabolism in breast cancer brain metastases

Brain metastases are among the most feared complications in breast cancer, as no therapy exists that prevents or eliminates breast cancer spreading to the brain. New therapeutic strategies depend on specific knowledge of tumor cell properties that allow breast cancer cell growth within the brain tissue. To provide information in this direction, we established a human breast cancer cell model for brain metastasis based on circulating tumor cells from a breast cancer patient and variants of these cells derived from bone or brain lesions in immunodeficient mice. The brain-derived cells showed an increased potential for brain metastasis in vivo and exhibited a unique protein expression profile identified by large-scale proteomic analysis. This protein profile is consistent with either a selection of predisposed cells or bioenergetic adaptation of the tumor cells to the unique energy metabolism of the brain. Increased expression of enzymes involved in glycolysis, tricarboxylic acid cycle, and oxidative phosphorylation pathways suggests that the brain metastatic cells derive energy from glucose oxidation. The cells further showed enhanced activation of the pentose phosphate pathway and the glutathione system, which can minimize production of reactive oxygen species resulting from an enhanced oxidative metabolism. These changes promoted resistance of brain metastatic cells to drugs that affect the cellular redox balance. Importantly, the metabolic alterations are associated with strongly enhanced tumor cell survival and proliferation in the brain microenvironment. Thus, our data support the hypothesis that predisposition or adaptation of the tumor cell energy metabolism is a key element in breast cancer brain metastasis, and raise the possibility of targeting the functional differentiation in breast cancer brain lesions as a novel therapeutic strategy.

Phase I study of capecitabine in combination with temozolomide in the treatment of patients with brain metastases from breast carcinoma

BACKGROUND

A single-institution Phase I clinical trial was conducted to determine the maximum tolerated dose (MTD) and define the safety profile of temozolomide and capecitabine when used in combination to treat brain metastases from breast cancer.

METHODS

Patients were eligible if they had bidimensionally measurable supratentorial or infratentorial brain metastasis from histologically confirmed breast carcinoma. Patients could have received up to 3 prior chemotherapy regimens. Temozolomide and capecitabine were administered concomitantly to 4 sequential cohorts at different dosing levels on Days 1-5 and Days 8-12, with cycles repeated every 21 days until disease progression.

RESULTS

Twenty-four patients with multiple brain lesions were treated, including 14 patients with newly diagnosed brain metastases and 10 patients with recurrent brain metastases. Only 1 patient was chemotherapy-naive. Fatigue and nausea were the most commonly observed toxicities observed at any dose levels. Significant antitumor activity was observed, with a total of 1 complete and 3 partial responses (18% objective response rate) in the brain. The median response duration was 8 weeks (range, 6-64 weeks) and the median time to progression in the brain was 12 weeks (range, 3-70 weeks). Neurocognitive function improved or remained stable in patients with a response or stable disease.

CONCLUSIONS

The combination of temozolomide and capecitabine is an active, well-tolerated regimen. The observed antitumor activity warrants further evaluation of this combination as an alternative to or in combination with whole-brain radiation therapy for the treatment of multiple brain metastases.