New Target Therapies for Brain Metastases from Breast Cancer

Defining the endpoints: how to measure the efficacy of drugs that are active against central nervous system metastases

Brain metastases (BMs) are the most common cause of malignant central nervous system (CNS) tumors in adults. In the recent past, patients with BMs were excluded from clinical trials, but now, with the advent of new biological and immunological drugs, their inclusion is more common. In the last era response and progression criteria used across clinical trials have defined the importance to consider not only measurement changes of brain lesions but also the modification of parameters related to the metastases such as metabolism of tissue and its pathological features. Magnetic resonance imaging (MRI) represents the first choice in the evaluation of BMs; the computed tomography (CT) scan will be made only in case of MRI's contraindication. CT, MRI and positron emission tomography (PET-CT), may be used to monitor response to treatment as part of clinical and radiological follow up. In the evaluation of response to treatment, MRI shows superior accuracy in comparison to CT; PET-CT is useful in particularly in cases of BMs underwent to locoregional therapies in the differential diagnosis between recurrence or radionecrosis. Now is possible to use functional imaging as CT-perfusion, dynamic susceptibility contrast (DSC) MR imaging, dynamic contrast-enhanced (DCE) MR imaging, diffusion-weighted MR imaging and MR-Spectroscopy in the evaluation of treatment response; these imaging techniques can provide qualitative and quantitative imaging parameters that allow pathophysiologic correlation. In the evaluation of the response to immunotherapy treatments, the immune-related response criteria (irRC) are considered as the gold standard. The irRC utilizes bidimensional measurements, quantifying the tumor dimension using a product of the longest diameter and the longest perpendicular diameter. We analyze clinical and radiological criteria to better define outcome of drugs for BMs from solid tumors in the new era of biological and immunological therapies.

First-line therapy in HER2 positive metastatic breast cancer: is the mosaic fully completed or are we missing additional pieces?

The discovery of human epidermal growth factor receptor 2 (HER2) and its role in the biology of breast cancer and the subsequent development of HER2-targeted therapies, have dramatically improved clinical outcomes for women with early-stage and advanced HER2-positive breast cancer (BC).

HER-2 targeted therapies represent a major step forward in achieving the goal of delivering individualized targeted therapy for BC, and trastuzumab was the first anti-HER-2 strategy to be approved for treatment of HER-2 positive BC.

This review discusses the treatment of metastatic HER2-positive BC and describes efficacy and safety of novel anti-HER2 target therapies in first-line metastatic settings and the future challenges include refining such treatments, reducing toxicity and simultaneously developing innovative therapies. Furthermore, combinations of trastuzumab and drugs targeting the downstream pathway are described.

In the next future will be possible to use an ample armamentarium of combination therapies directed against HER2 and key signaling components integrated in the HER network. This approach will allow clinicians to tailor the management of the individual patient on the basis of tumor- specific biomarker profiles.

There is an urgent need for prospective biomarker-driven trials to identify patients for whom targeting is cost-effective.

A New Herbal Formula, KSG-002, Suppresses Breast Cancer Growth and Metastasis by Targeting NF- κ B-Dependent TNF α Production in Macrophages

Tumor-associated macrophages (TAMs) in tumor microenvironment regulate cancer progression and metastases. In breast cancer, macrophage infiltration is correlated with a poor prognosis. While metastatic breast cancer is poor prognostic with a severe mortality, therapeutic options are still limited. In this study, we demonstrate that KSG-002, a new herbal composition of radices Astragalus membranaceus and Angelica gigas, suppresses breast cancer via inhibiting TAM recruitment. KSG-002, an extract of radices Astragalus membranaceus and Angelica gigas at 3 : 1 ratio, respectively, inhibited MDA-MB-231 xenograft tumor growth and pulmonary metastasis in nude mice, while KSG-001, another composition (1 : 1 ratio, w/w), enhanced tumor growth, angiogenesis, and pulmonary metastasis, in vivo. KSG-002 further decreased the infiltrated macrophage numbers in xenograft tumor cohorts. In Raw264.7 cells, KSG-002 but not KSG-001 inhibited cell proliferation and migration and reduced TNF-alpha (TNF α ) production by inhibiting NF- κ B pathway. Furthermore, a combinatorial treatment of KSG-002 with TNF α inhibited a proliferation and migration of both MDA-MB-231 and Raw264.7 cells. Taken together, we conclude that KSG-002 suppresses breast cancer growth and metastasis through targeting NF- κ B-mediated TNF α production in macrophages.

Frequent genetic alterations in EGFR- and HER2-driven pathways in breast cancer brain metastases

Current standard systemic therapies for treating breast cancer patients with brain metastases are inefficient. Targeted therapies against human epidermal growth factor receptors are of clinical interest because of their alteration in a subset of breast cancers (BCs). We analyzed copy number, mutation status, and protein expression of epidermal growth factor receptor (EGFR), human epidermal growth factor 2 (HER2), phosphatase and tensin homologue (PTEN), and PI3K catalytic subunit (PIK3CA) in 110 ductal carcinoma in situ, primary tumor, and metastatic BC samples. Alterations in EGFR, HER2, and PTEN, alone or in combination, were found in a significantly larger fraction of breast cancer brain metastases tumor tissue compared with samples from primary tumors with good prognosis, bone relapse, or other distant metastases (all P < 0.05). Primary tumor patients with a subsequent brain relapse showed almost equally high frequencies of especially EGFR and PTEN alteration as the breast cancer brain metastases patients. PIK3CA was not associated with an increased risk of brain metastases. Genetic alterations in both EGFR and PTEN were especially common in triple-negative breast cancer patients and rarely were seen among HER2-positive patients. In conclusion, we identified two independent high-risk primary BC subgroups for developing brain metastases, represented by genetic alterations in either HER2 or EGFR/PTEN-driven pathways. In contrast, none of these pathways was associated with an increased risk of bone metastasis. These findings highlight the importance of both pathways as possible targets in the treatment of brain metastases in breast cancer.

Targeted therapy for brain metastases

The prevention and treatment of brain metastases is an increasingly important challenge in oncology. Improved understanding of the molecular pathogenesis of a number of cancers has led to the development of highly active targeted therapies for patients with specific oncogenic events. Such therapies include EGFR inhibitors for lung cancer, HER2/neu inhibitors for breast cancer, and BRAF inhibitors for melanoma. This review will discuss the development of these targeted therapy approaches, existing data about their role in the management of brain metastasis, and opportunities and challenges for future research in this critical area.