Targeted Therapies for Brain Metastases from Breast Cancer. Int J Mol Sci. 2016;17:1543. [PMID: 27649142 PMCID: PMC5037817 DOI: 10.3390/ijms17091543]

Recent advances in managing brain metastasis

Brain metastases are the most common malignancy encountered in the central nervous system (CNS), with up to 30-40% of cancer patients developing brain metastases at some point during the course of their disease. The management of brain metastasis is rapidly evolving and the roles of local therapies such as whole-brain radiation therapy, stereotactic radiosurgery, and resection along with systemic therapies are in flux. An emphasis on the neurocognitive side effects associated with treatment has gained prominence. Novel molecular studies have demonstrated important evolutionary patterns underpinning the development of brain metastasis and leptomeningeal disease, which may be key to unlocking new therapeutic strategies. This article provides a framework for incorporating the results of recent randomized radiotherapy clinical trials into practice, expounds upon the emphasis on cognition being an important driver in therapeutic selection, describes the importance of CNS-penetrating systemic therapies, and provides an overview of the novel molecular insights that will likely set the stage for future developments in this field.

Emerging Gene Fusion Drivers in Primary and Metastatic Central Nervous System Malignancies: A Review of Available Evidence for Systemic Targeted Therapies

Primary and metastatic tumors of the central nervous system present a difficult clinical challenge, and they are a common cause of disease progression and death. For most patients, treatment consists primarily of surgery and/or radiotherapy. In recent years, systemic therapies have become available or are under investigation for patients whose tumors are driven by specific genetic alterations, and some of these targeted treatments have been associated with dramatic improvements in extracranial and intracranial disease control and survival. However, the success of other systemic therapies has been hindered by inadequate penetration of the drug into the brain parenchyma. Advances in molecular characterization of oncogenic drivers have led to the identification of new gene fusions driving oncogenesis in some of the most common sources of intracranial tumors. Systemic therapies targeting many of these alterations have been approved recently or are in clinical development, and the ability to penetrate the blood-brain barrier is now widely recognized as an important property of such drugs. We review this rapidly advancing field with a focus on recently uncovered gene fusions and brain-penetrant systemic therapies targeting them.

IMPLICATIONS FOR PRACTICE

Driver gene fusions involving receptor tyrosine kinases have been identified across a wide range of tumor types, including primary central nervous system (CNS) tumors and extracranial solid tumors that are associated with high rates of metastasis to the CNS (e.g., lung, breast, melanoma). This review discusses the systemic therapies that target emerging gene fusions, with a focus on brain-penetrant agents that will target the intracranial disease and, where present, also extracranial disease.

Contributions of Thyroid Hormone to Cancer Metastasis

Acting at a cell surface receptor on the extracellular domain of integrin αvβ3, thyroid hormone analogues regulate downstream the expression of a large panel of genes relevant to cancer cell proliferation, to cancer cell survival pathways, and to tumor-linked angiogenesis. Because αvβ3 is involved in the cancer cell metastatic process, we examine here the possibility that thyroid hormone as l-thyroxine (T4) and the thyroid hormone antagonist, tetraiodothyroacetic acid (tetrac), may respectively promote and inhibit metastasis. Actions of T4 and tetrac that are relevant to cancer metastasis include the multitude of synergistic effects on molecular levels such as expression of matrix metalloproteinase genes, angiogenesis support genes, receptor tyrosine kinase (EGFR/ERBB2) genes, specific microRNAs, the epithelial–mesenchymal transition (EMT) process; and on the cellular level are exemplified by effects on macrophages. We conclude that the thyroid hormone-αvβ3 interaction is mechanistically linked to cancer metastasis and that modified tetrac molecules have antimetastatic activity with feasible therapeutic potential.

Current Therapies for Human Epidermal Growth Factor Receptor 2-Positive Metastatic Breast Cancer Patients

The median survival of patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) has more than doubled, since the discovery of HER2-targeted treatments: it rose from less than 2 years in 2001 (prior introduction of trastuzumab) to more than 4 years in 2017. The initial generation of HER2-targeted therapies included trastuzumab with taxanes in the first line, followed by the addition of lapatinib and by a switch to another cytotoxic agent after progression. Results of CLEOPATRA, EMILIA, and TH3RESA trials have changed this clinical practice. The current consensus includes horizontal dual blockade (trastuzumab + pertuzumab) with taxanes or vinorelbine in the first line, followed by trastuzumab-emtansine (T-DM1) in the second line, with addition of lapatinib in the later lines of treatment. However, the fast and simultaneous development of new drugs led to a relative shortage of clinical evidence to support this sequence. Triple-positive breast cancers (TPBC), which express both hormonal receptors and HER2, constitute nearly half of HER2-positive cases. For these tumors, the current consensus is to add endocrine therapy after completion of cytotoxic treatment. Again, this consensus is not fully evidence-based. In view of the recent progress in treatment of estrogen-receptor positive breast cancers, a series of trials is evaluating addition of CDK4/6 inhibitors, aromatase inhibitors or fulvestrant to HER2-targeted and cytotoxic chemotherapy in TPBC patients. Despite the remarkable progress in treatment of HER2-positive breast cancer, metastatic disease is still incurable in the majority of patients. A wide range of novel therapies are under development to prevent and overcome resistance to current HER2-targeted agents. This review discusses pivotal clinical trials that have shaped current clinical practices, the current consensus recommendations, and the new experimental treatments in metastatic HER2-positive breast cancer.

Systemic therapy for brain metastases

Central nervous system metastases cause grave morbidity in patients with advanced malignancies. Lung cancer, breast cancer, and melanoma are the three most common causes of brain metastases. Although the exact incidence of brain metastases is unclear, there appears to be an increasing incidence which has been attributed to longer survival, better control of systemic disease, and better imaging modalities. Until recently surgical resection of solitary or symptomatic brain metastases, and radiation therapy (either whole-brain radiation therapy or stereotactic radiation) were the mainstay of treatment for patients with brain metastases. The majority of traditional chemotherapies have shown limited activity in the central nervous system, which has been attributed to the blood-brain barrier and the molecular structure of the used agents. The discovery of driver mutations and drugs targeting these mutations has changed the treatment landscape. Several of these targeted small-molecule tyrosine kinase inhibitors do cross the blood-brain barrier and/or have shown activity in the central nervous system. Another major advance in the care of brain metastases has been the advent of new immunotherapeutic agents, for which initial studies have shown intracranial activity. In this chapter, we will review the unique challenges in the treatment of brain metastases. The pertinent clinical studies of chemotherapy in brain metastases will be discussed. The currently reported clinical trials and evidence for use of targeted therapies and immunotherapeutic agents will be emphasized.

Comprehensive molecular biomarker identification in breast cancer brain metastases

Background

Breast cancer brain metastases (BCBM) develop in about 20–30% of breast cancer (BC) patients. BCBM are associated with dismal prognosis not at least due to lack of valuable molecular therapeutic targets. The aim of the study was to identify new molecular biomarkers and targets in BCBM by using complementary state-of-the-art techniques.

Methods

We compared array expression profiles of three BCBM with 16 non-brain metastatic BC and 16 primary brain tumors (prBT) using a false discovery rate (FDR) p < 0.05 and fold change (FC) > 2. Biofunctional analysis was conducted on the differentially expressed probe sets. High-density arrays were employed to detect copy number variations (CNVs) and whole exome sequencing (WES) with paired-end reads of 150 bp was utilized to detect gene mutations in the three BCBM.

Results

The top 370 probe sets that were differentially expressed between BCBM and both BC and prBT were in the majority comparably overexpressed in BCBM and included, e.g. the coding genes BCL3, BNIP3, BNIP3P1, BRIP1, CASP14, CDC25A, DMBT1, IDH2, E2F1, MYCN, RAD51, RAD54L, and VDR. A number of small nucleolar RNAs (snoRNAs) were comparably overexpressed in BCBM and included SNORA1, SNORA2A, SNORA9, SNORA10, SNORA22, SNORA24, SNORA30, SNORA37, SNORA38, SNORA52, SNORA71A, SNORA71B, SNORA71C, SNORD13P2, SNORD15A, SNORD34, SNORD35A, SNORD41, SNORD53, and SCARNA22. The top canonical pathway was entitled, role of BRCA1 in DNA damage response. Network analysis revealed key nodes as Akt, ERK1/2, NFkB, and Ras in a predicted activation stage. Downregulated genes in a data set that was shared between BCBM and prBT comprised, e.g. BC cell line invasion markers JUN, MMP3, TFF1, and HAS2. Important cancer genes affected by CNVs included TP53, BRCA1, BRCA2, ERBB2, IDH1, and IDH2. WES detected numerous mutations, some of which affecting BC associated genes as CDH1, HEPACAM, and LOXHD1.

Conclusions

Using complementary molecular genetic techniques, this study identified shared and unshared molecular events in three highly aberrant BCBM emphasizing the challenge to detect new molecular biomarkers and targets with translational implications. Among new findings with the capacity to gain clinical relevance is the detection of overexpressed snoRNAs known to regulate some critical cellular functions as ribosome biogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12967-017-1370-x) contains supplementary material, which is available to authorized users.

CYP1A1 genetic polymorphism is a promising predictor to improve chemotherapy effects in patients with metastatic breast cancer treated with docetaxel plus thiotepa vs. docetaxel plus capecitabine

PURPOSE

A prospective study was performed to compare the outcome for metastatic breast cancer (MBC) patients treated with docetaxel plus thiotepa (DT) or docetaxel plus capecitabine (DC), and to explore the value of CYP1A1*2C polymorphisms in predicting clinical efficacy of these chemotherapies.

METHODS

MBC patients (n = 130) were randomized to treatment with DT (n = 65) or DC (n = 65). Response rate, disease control rate, progression-free and overall survival were monitored. Genotyping of CYP1A1*2C was performed in all patients.

RESULTS

DT and DC produced similar overall disease control rates (76.9 vs 69.2%), median PFS (6.7 vs. 7.5 months) and OS (20.1 vs. 21.0 months) (P > 0.05 for all comparisons); however, DT exhibited a higher rate of control of localized liver metastases (78.6 vs 41.2%, P = 0.023). Among patients homozygous for wild-type CYP1A1*1 genotype (AA), DT treatment was associated with a significantly longer PFS (8.4 vs. 6.4 months, P = 0.019) and OS (33.4 vs. 15.8 months, P = 0.018). Conversely, among patients carrying the variant CYP1A1*2C genotype (AG/GG), DC treatment was associated with a significantly longer PFS (8.4 vs. 5.5 month, P = 0.005), and OS (28.5 vs. 19.6 months, P = 0.010). After adjusting for competing risk factors, CYP1A1*2C genotype was confirmed to be an independent predictor of PFS and OS for each chemotherapy combination.

CONCLUSIONS

Overall, DT and DC result in similar clinical efficacy for MBC patients; however, efficacy for each therapy differs depending on CYP1A1*2C genotype.

Genetic Characterization of Brain Metastases in the Era of Targeted Therapy

In the current era of molecularly targeted therapies and precision medicine, choice of cancer treatment has been increasingly tailored according to the molecular or genomic characterization of the cancer the individual has. Previously, the clinical observation of inadequate control of brain metastases was widely attributed to a lack of central nervous system (CNS) penetration of the anticancer drugs. However, more recent data have suggested that there are genetic explanations for such observations. Genomic analyses of brain metastases and matching primary tumor and other extracranial metastases have revealed that brain metastases can harbor potentially actionable driver mutations that are unique to them. Identification of genomic alterations specific to brain metastases and targeted therapies against these mutations represent an important research area to potentially improve survival outcomes for patients who develop brain metastases. Novel approaches in genomic testing such as that using cell-free circulating tumor DNA (ctDNA) in the cerebrospinal fluid (CSF) facilitate advancing our understanding of the genomics of brain metastases, which is critical for precision medicine. CSF-derived ctDNA sequencing may be particularly useful in patients who are unfit for surgical resection or have multiple brain metastases, which can harbor mutations that are distinct from their primary tumors. Compared to the traditional chemotherapeutics, novel targeted agents appear to be more effective in controlling the CNS disease with better safety profiles. Several brain metastases-dedicated trials of various targeted therapies are currently underway to address the role of these agents in the treatment of CNS disease. This review focuses on recent advances in genomic profiling of brain metastases and current knowledge of targeted therapies in the management of brain metastases from cancers of the breast, lung, colorectum, kidneys, and ovaries as well as melanoma.

Novel therapeutic agents in the management of brain metastases

PURPOSE OF REVIEW

This review aims to highlight the novel therapeutic agents in the management of brain metastases which are in various stages of clinical development. We review the results from recent clinical trials, publications and presentations at recent national and international conferences.

RECENT FINDINGS

Several new systemic treatment options for brain metastases are in early or advanced clinical trials. These drugs have good intracranial and extracranial activities. As lung cancer, breast cancer, and melanoma are the three most common causes of brain metastases, most agents in clinical development are focused on these tumor types. Several of these therapies are small molecule tyrosine kinase inhibitors or monoclonal antibodies against the tyrosine kinase receptors. Another exciting development in brain metastases management is the use of immunotherapy agents. The anti-CTLA-4 and\or anti-PD-1 antibodies have shown promising intracranial activity in melanoma and nonsmall cell lung cancer patients with brain metastases.

SUMMARY

Contemporary clinical trials have shown encouraging intracranial activity of newer tyrosine kinase inhibitors, monoclonal antibodies against tyrosine kinase receptors and immunotherapy agents in select group of patients with brain metastases. Further studies are needed to develop therapeutic strategies, in order to improve survival in patients with brain metastases.

The efficacy of lapatinib and capecitabine in HER-2 positive breast cancer with brain metastases: A systematic review and pooled analysis

INTRODUCTION

Breast cancer (BC) with HER-2/neu overexpression or amplification (HER-2+) is associated with a higher prevalence of brain metastases (BMs) when compared to other subtypes. Among approved drugs for HER-2+ BC, lapatinib (L) is associated with single agent activity toward BMs. We conducted a systematic review to determine the efficacy of L, singly or in combination with capecitabine (C), as a treatment for HER-2+ BMs.

MATERIAL AND METHODS

We searched PubMed, EMBASE, The Cochrane Library, SCOPUS, Web of Science, ClinicalTrials.gov, World Health Organization International Clinical Trials Registry Platform (ICTRP), and the European Union Clinical Trials Register for studies reporting data on L, singly or in combination with C, for the treatment of HER-2+ BC with BMs. Primary end-points were overall response rate (ORR) and disease control rate (DCR); these were pooled to provide an aggregate value. Progression-free survival (PFS) and overall survival (OS) were secondary end-points. Data were pooled using number of events/number of evaluable patients, according to a fixed or random effect model.

RESULTS

Overall, 12 studies were included in the present meta-analysis, for a total of 799 patients with BMs. The pooled overall response rate (ORR) was 21.4% (95% CI 11.7-35.9). After exclusion of patients that received L alone, ORR reached 29.2% (95% CI 18.5-42.7). The pooled median PFS and OS were 4.1 (95% CI 3.1-6.7) and 11.2 (95% CI 8.9-14.1) months, respectively.

CONCLUSIONS

Due to its activity on BMs, the L + C combination may be considered for HER-2+ BC that has progressed in the brain, when local therapy has been performed or failed and re-irradiation is not feasible.

Mutations targeting the coagulation pathway are enriched in brain metastases

Brain metastases (BMs) are the most common malignancy of the central nervous system. Recently it has been demonstrated that plasminogen activator inhibitor serpins promote brain metastatic colonization, suggesting that mutations in serpins or other members of the coagulation cascade can provide critical advantages during BM formation. We performed whole-exome sequencing on matched samples of breast cancer and BMs and found mutations in the coagulation pathway genes in 5 out of 10 BM samples. We then investigated the mutational status of 33 genes belonging to the coagulation cascade in a panel of 29 BMs and we identified 56 Single Nucleotide Variants (SNVs). The frequency of gene mutations of the pathway was significantly higher in BMs than in primary tumours, and SERPINI1 was the most frequently mutated gene in BMs. These findings provide direction in the development of new strategies for the treatment of BMs.

Mystery of the brain metastatic disease in breast cancer patients: improved patient stratification, disease prediction and targeted prevention on the horizon?

The breast cancer (BC) diagnosis currently experiences the epidemic evolution with more than half of million deaths each year. Despite screening programmes applied and treatments available, breast cancer patients frequently develop distant metastases. The brain is one of the predominant sites of the metastatic spread recorded for more than 20% of BC patients, in contrast to the general population, where brain tumours are rarely diagnosed. Although highly clinically relevant, the brain tumour mystery in the cohort of breast cancer patients has not been yet adequately explained. This review summarises currently available information on the risk factors predicting brain metastases in BC patients to motivate the relevant scientific areas to explore the data/facts available and elucidate disease-specific mechanisms that are of a great clinical utility.

Impact of molecular subtypes on metastatic breast cancer patients: a SEER population-based study

To investigate the significance and impact of molecular subtyping stratification on metastatic breast cancer patients, we identified 159,344 female breast cancer patients in the Surveillance, Epidemiology and End Results (SEER) database with known hormone receptor (HoR) and human epidermal growth factor receptor 2 (HER2) status. 4.8% of patients were identified as having stage IV disease, and were more likely to be HER2+/HoR−, HER2+/HoR+, or HER2−/HoR−. Stage IV breast cancer patients with a HER2+/HoR+ status exhibited the highest median overall survival (OS) (44.0 months) and those with a HER2−/HoR− status exhibited the lowest median OS (13.0 months). Patients with a HER2−/HoR+ status had more bone metastasis, whereas patients with a HER2+/HoR− status had an increased incidence of liver metastasis. Brain and lung metastasis were more likely to occur in women with a HER2−/HoR− status. The multivariable analysis revealed a significant interaction between single metastasis and molecular subtype. No matter which molecular subtype, women who did not undergo primary tumour surgery had worse survival than those who experienced primary tumour surgery. Collectively, our findings advanced the understanding that molecular subtype might lead to more tailored and effective therapies in metastatic breast cancer patients.

Oncolytic viruses: emerging options for the treatment of breast cancer

Breast cancer (BC) is the most common type of cancer among women and is the second most common cause of cancer-related deaths, following lung cancer. Severe toxicity associated with a long-term use of BC chemo- and radiotherapy makes it essential to look for newer therapeutics. Additionally, molecular heterogeneity at both intratumoral and intertumoral levels among BC subtypes is known to result in a differential response to standard therapeutics. Oncolytic viruses (OVs) have emerged as one of the most promising treatment options for BC. Many preclinical and clinical studies have shown that OVs are effective in treating BC, both as a single therapeutic agent and as a part of combination therapies. Combination therapies involving multimodal therapeutics including OVs are becoming popular as they allow to achieve the synergistic therapeutic effects, while minimizing the associated toxicities. Here, we review the OVs for BC therapy in preclinical studies and in clinical trials, both as a monotherapy and as part of a combination therapy. We also briefly discuss the potential therapeutic targets for BC, as these are likely to be critical for the development of new OVs.

Targeted therapy for leptomeningeal metastases in non-small cell lung cancer - Changing treatment paradigms

Leptomeningeal metastasis is an uncommon but serious complication in patients with advanced cancers. Leptomeningeal metastasis is diagnosed in approximately 5% of the patients, most commonly among patients with cancers of breast and lung, melanoma, and gastrointestinal malignancies. Treatment goal is to improve survival and quality of the patients. Use of targeted therapies and immunotherapy has led to improved survival of patients with non-small cell lung cancer (NSCLC). In this article, we review emerging data on use of mutation-specific agents and immunotherapy in the treatment of leptomeningeal metastasis among patients with NSCLC.

Site of metastasis and breast cancer mortality: a Danish nationwide registry-based cohort study

Survival among patients with metastatic breast cancer may vary according to the site of metastasis and receptor status. We used Danish nationwide medical registries to establish a cohort of patients with metastatic breast cancer (870 with de novo metastatic disease and 3518 with recurrent disease with distant metastasis) diagnosed during 1997-2011. We examined 1-year and >1 to 5-year mortality associated with first site of metastasis and receptor expression status of the primary tumor. Cox proportional regression was used to compute confounder-adjusted mortality rate ratios (MRRs) associated with site of metastasis, stratified by receptor status. Overall 1-year and >1 to 5-year mortality risks were 36 and 69 %, respectively. Risk of death within 1 year was highest for brain-only (62 %) and liver-only (43 %) involvement and nearly the same for patients with lung-only (32 %), bone-only (32 %) involvement, and other/combination of sites (34 %). Using bone-only metastasis as reference, women with brain-only metastasis had more than two-fold increased risk of dying. The adjusted MRR for women with liver-only metastasis also was increased, though less pronounced. Patients with lung-only [adjusted MRR 0.9 (95 % confidence interval (CI) 0.8, 1.1)] or other metastases [adjusted MRR 1.0 (95 % CI 0.9, 1.2)] had similar mortality as patients with bone-only metastasis. Positive hormonal receptor status was a favorable prognostic factor. Metastatic breast cancer has a serious prognosis. Patients with brain-only metastasis had the highest mortality. Positive hormonal receptor status on the primary tumor was a favorable prognostic factor for all metastatic sites.