Breast Cancer in the Central Nervous System: Multidisciplinary Considerations and Management

Systematic review of the management of brain metastases from hormone receptor positive breast cancer

INTRODUCTION

Brain metastases are a common cause of morbidity and mortality in patients with breast cancer. Local central nervous system (CNS) directed therapies are usually the first line treatment for breast cancer brain metastases (BCBM), but those must be followed by systemic therapies to achieve long-term benefit. Systemic therapy for hormone receptor (HR⁺) breast cancer has evolved in the last 10 years, but their role when brain metastases occur is uncertain.

METHODS

We performed a systematic review of the literature focused on management of HR⁺ BCBM by searching Medline/PubMed, EBSCO, and Cochrane databases. The PRISMA guidelines were used for systematic review.

RESULTS

Out of 807 articles identified, 98 fulfilled the inclusion criteria in their relevance to the management of HR⁺ BCBM.

CONCLUSIONS

Similar to brain metastases from other neoplasms, local CNS directed therapies are the first line treatment for HR⁺ BCBM. Although the quality of evidence is low, after local therapies, our review supports the combination of targeted and endocrine therapies for both CNS and systemic management. Upon exhaustion of targeted/endocrine therapies, case series and retrospective reports suggest that certain chemotherapy agents are active against HR⁺ BCBM. Early phase clinical trials for HR⁺ BCBM are ongoing, but there is a need for prospective randomized trials to guide management and improve patients' outcome.

Systemic Therapy Type and Timing Effects on Radiation Necrosis Risk in HER2+ Breast Cancer Brain Metastases Patients Treated With Stereotactic Radiosurgery

Background

There is a concern that HER2-directed systemic therapies, when administered concurrently with stereotactic radiosurgery (SRS), may increase the risk of radiation necrosis (RN). This study explores the impact of timing and type of systemic therapies on the development of RN in patients treated with SRS for HER2+ breast cancer brain metastasis (BCBrM).

Methods

This was a single-institution, retrospective study including patients >18 years of age with HER2+ BCBrM who received SRS between 2013 and 2018 and with at least 12-month post-SRS follow-up. Presence of RN was determined via imaging at one-year post-SRS, with confirmation by biopsy in some patients. Demographics, radiotherapy parameters, and timing (“during” defined as four weeks pre- to four weeks post-SRS) and type of systemic therapy (e.g., chemotherapy, HER2-directed) were evaluated.

Results

Among 46 patients with HER2+ BCBrM who received SRS, 28 (60.9%) developed RN and 18 (39.1%) did not based on imaging criteria. Of the 11 patients who underwent biopsy, 10/10 (100%) who were diagnosed with RN on imaging were confirmed to be RN positive on biopsy and 1/1 (100%) who was not diagnosed with RN was confirmed to be RN negative on biopsy. Age (mean 53.3 vs 50.4 years, respectively), radiotherapy parameters (including total dose, fractionation, CTV and size target volume, all p>0.05), and receipt of any type of systemic therapy during SRS (60.7% vs 55.6%, p=0.97) did not differ between patients who did or did not develop RN. However, there was a trend for patients who developed RN to have received more than one agent of HER2-directed therapy independent of SRS timing compared to those who did not develop RN (75.0% vs 44.4%, p=0.08). Moreover, a significantly higher proportion of those who developed RN received more than one agent of HER2-directed therapy during SRS treatment compared to those who did not develop RN (35.7% vs 5.6%, p=0.047).

Conclusions

Patients with HER2 BCBrM who receive multiple HER2-directed therapies during SRS for BCBrM may be at higher risk of RN. Collectively, these data suggest that, in the eight-week window around SRS administration, if HER2-directed therapy is medically necessary, it is preferable that patients receive a single agent.

Prognostic Factors and Survival Outcomes among Patients with Breast Cancer and Brain Metastases at Diagnosis: A National Cancer Database Analysis

INTRODUCTION

The aim of this study was to assess for clinicopathologic and socioeconomic features that predict improved survival for patients with advanced breast cancer with synchronous brain metastases at diagnosis.

METHODS

We utilized the National Cancer Database (NCDB) to identify all patients with brain metastases present at diagnosis, with adequate information on receptor status (ER, PR, Her2), clinical T stage of cT1-4, clinical M1, with 3,943 patients available for analysis. The association between brain metastases patterns and patient/disease variables was examined by robust Poisson regression model. Cox proportional hazards model was used to quantify the associations between overall survival (OS) and these variables.

RESULTS

In univariable analysis, OS was significantly associated with the number of sites of metastases (p < 0.0001). Patients with 2 or more additional extracranial sites of metastases had significantly worse OS (median 8.8 months, 95% confidence interval [CI] 7.8, 9.9) than patients with brain metastases only (median OS 10.6 months, 95% CI 9.4, 12.9) or brain metastases plus one other extracranial site of metastases (median OS 13.1 months, 95% CI 11.8, 14.4). Risk factors which predicted poor prognosis included triple-negative disease, high comorbidity score, poorly differentiated tumors, invasive lobular histology, multi-organ involvement of metastases, and government or lack of insurance. Factors which improve survival include younger age and Hispanic race.

DISCUSSION/CONCLUSION

Using a large NCDB, we identified various factors associated with prognosis for patients with brain metastases at the time of breast cancer diagnosis. Insurance status and related socioeconomic challenges provide potential areas for improvement in care for these patients. This information may help stratify patients into prognostic categories at the time of diagnosis to improve treatment plans.

Evolving standards of care and new challenges in the management of HER2-positive breast cancer

The management of human epidermal growth factor receptor (HER2)-positive breast cancer (BC) has rapidly evolved over the last 20 years. Major advances have led to US Food and Drug Administration approval of 7 HER2-targeted therapies for the treatment of early-stage and/or advanced-stage disease. Although oncologic outcomes continue to improve, most patients with advanced HER2-positive BC ultimately die of their disease because of primary or acquired resistance to therapy, and patients with HER2-positive early BC who have residual invasive disease after preoperative systemic therapy are at a higher risk of distant recurrence and death. The concept of treatment de-escalation and escalation is increasingly important to optimally tailor therapy for patients with HER2-positive BC and is a major focus of the current review. Research efforts in this regard are discussed as well as updates regarding the evolving standard of care in the (neo)adjuvant and metastatic settings, including the use of novel combination therapies. The authors also briefly discuss ongoing challenges in the management of HER2-positive BC (eg, intrinsic vs acquired drug resistance, the identification of predictive biomarkers, the integration of imaging techniques to guide clinical practice), and the treatment of HER2-positive brain metastases. Research aimed at superseding these challenges will be imperative to ensure continued progress in the management of HER2-positive BC going forward.

Emerging treatment strategies for breast cancer brain metastasis: from translational therapeutics to real-world experience

Systemic therapies for primary breast cancer have made great progress over the past two decades. However, oncologists confront an insidious and particularly difficult problem: in those patients with metastatic breast cancer, up to 50% of human epidermal growth factor 2 (HER2)-positive and 25-40% of triple-negative subtypes, brain metastases (BM) kill most of them. Fortunately, standard- of-care treatments for BM have improved rapidly, with a decline in whole brain radiation therapy and use of fractionated stereotactic radiosurgery as well as targeted therapies and immunotherapies. Meanwhile, advances in fundamental understanding of the basic biological processes of breast cancer BM (BCBM) have led to many novel experimental therapeutic strategies. In this review, we describe the most recent clinical treatment options and emerging experimental therapeutic strategies that have the potential to combat BCBM.

Identification of risk factors for central nervous system metastasis in patients with breast cancer with neurologic symptoms

BACKGROUND

The current study was performed to identify factors that are present at the time of breast cancer (BC) diagnosis that are associated with a higher rate of central nervous system metastasis (CNSm).

METHODS

The authors analyzed a database of patients with a confirmed diagnosis of BC who were referred for a neuro-oncology consultation at the National Cancer Institute in Mexico City, Mexico, from June 2009 to June 2017. Information was collected prospectively and included demographic, pathologic, and clinical data at the time of diagnosis of BC. Bivariate and multivariate logistic regression models were built to estimate the associations between the development of CNSm and the time after BC diagnosis.

RESULTS

Among 970 patients with BC, 263 (27%) were diagnosed with CNSm. The median time from BC diagnosis to the development of CNSm was 33 months (interquartile range, 15-76 months). After multivariate analysis, age <50 years at the time of BC diagnosis (odds ratio [OR], 2.5; 95% confidence interval [95% CI], 1.8-3.5 [P < .0001]), human epidermal growth factor receptor 2 (HER2)-positive status (HER2+) (OR, 3.6; 95% CI, 2.1-6.1 [P < .0001]), luminal B/HER2+ subtype (OR, 3.1; 95% CI, 1.9-5.3 [P < .001]), triple-negative subtype(OR, 2.4; 95% CI, 1.5-4 [P = .001]), and Karnofsky performance status ≤70 (OR, 6.6; 95% CI, 4.5-9.6 [P < .0001]) were associated with a higher frequency of CNSm. Brain parenchyma was the most common site of CNSm. The median overall survival after a diagnosis of CNSm was 12.2 months (95% CI, 9.3-15.1 months).

CONCLUSIONS

CNSm is not uncommon among patients with BC, particularly in those with neurologic symptoms who require neuro-oncology evaluation and are aged <50 years at the time of diagnosis, have HER2+ or triple-negative subtypes, have a poor Karnofsky performance status, and/or have ≥2 non-CNS metastases.

Systemic treatment of breast cancer with leptomeningeal metastases using bevacizumab, etoposide and cisplatin (BEEP regimen) significantly improves overall survival

Introduction

Metastatic breast cancer (MBC) with leptomeningeal metastases (LM) has dismal survival. We aim to determine if modern systemic therapy, especially the bevacizumab, cisplatin, and etoposide (BEEP) regimen, is beneficial to MBC LM patients.

Methods

We excerpted data from a prospectively collected cytopathology database for MBC patients who were diagnosed with LM by positive cerebrospinal fluid cytology. The primary outcome was OS from cytologically confirmed LM until death. Univariate and multivariate analyses were performed to elucidate prognostic factors.

Results

We identified 34 patients with cytologically confirmed LM. Treatments after LM diagnosis included: intrathecal methotrexate (82.4%), systemic chemotherapy (68%; BEEP n = 19, others n = 4), and whole brain radiotherapy (n = 5, 14.7%). Three of seven HER2-positive patients (43%) also received intrathecal trastuzumab. OS was improved in 2014–2016 compared with 2011–2013 (13.57 vs 3.20 months, p = 0.004), when 12/17 (71%) versus 7/17 (41%) patients received BEEP, respectively. In the multivariate model including all treatments, BEEP (HR 0.24, p = 0.003) and intrathecal trastuzumab (HR 0.22, p = 0.035), but not intrathecal methotrexate (HR 0.86, p = 0.78), remained significant prognostic factors.

Conclusions

MBC with LM is treatable—systemic BEEP are efficacious and may improve survival.

Electronic supplementary material

The online version of this article (10.1007/s11060-020-03510-y) contains supplementary material, which is available to authorized users.

Systemic therapy following craniotomy in patients with a solitary breast cancer brain metastasis

Purpose

To describe practice patterns and patient outcomes with respect to the use of postoperative systemic therapy (ST) after resection of a solitary breast cancer brain metastasis (BCBM).

Methods

A multi-institutional retrospective review of consecutive patients undergoing resection of a single BCBM without extracranial metastases was performed to describe subtype-specific postoperative outcomes and assess the impact of types of ST on site of recurrence, progression-free survival (PFS), and overall survival (OS).

Results

Forty-four patients were identified. Stratified estimated survival was 15, 24, and 23 months for patients with triple negative, estrogen receptor positive (ER+), and HER2+ BCBMs, respectively. Patients receiving postoperative ST had a longer median PFS (8 versus 4 months, adjusted p-value 0.01) and OS (32 versus 15 months, adjusted p-value 0.21). Nine patients (20%) had extracranial progression, 23 (52%) had intracranial progression, three (8%) had both, and nine (20%) did not experience progression at last follow-up. Multivariate analysis showed that postoperative hormonal therapy was associated with longer OS (HR 0.26; 95% CI 0.08–0.89; p = 0.03) but not PFS (HR 0.35, 95% CI 0.08–1.47, p = 0.15) in ER+ patients. Postoperative HER2-targeted therapy was not associated with longer OS or PFS in HER2+ patients.

Conclusions

Disease progression occurred intracranially more often than extracranially following resection of a solitary BCBM. In ER+ patients, postoperative hormonal therapy was associated with longer OS. Postoperative HER2-targeted therapy did not show survival benefit in HER2+ patients. These results should be validated in larger cohorts.

Impact of breast cancer molecular subtypes on the incidence, kinetics and prognosis of central nervous system metastases in a large multicentre real-life cohort

BACKGROUND

Metastatic breast cancer (MBC) behaviour differs depending on hormone receptors (HR) and human epidermal growth factor receptor (HER2) statuses.

METHODS

The kinetics of central nervous system (CNS) metastases (CNS metastasis-free survival, CNSM-FS) and subsequent patient's prognosis (overall survival, OS) according to the molecular subtype were retrospectively assessed in 16703 MBC patients of the ESME nationwide multicentre MBC database (Kaplan-Meier method).

RESULTS

CNS metastases occurred in 4118 patients (24.6%) (7.2% at MBC diagnosis and 17.5% later during follow-up). Tumours were HER2-/HR+ (45.3%), HER2+/HR+ (14.5%), HER2+/HR- (14.9%) and triple negative (25.4%). Median age at CNS metastasis diagnosis was 58.1 years (range: 22.8-92.0). The median CNSM-FS was 10.8 months (95% CI: 16.5-17.9) among patients who developed CNS metastases. Molecular subtype was independently associated with CNSM-FS (HR = 3.45, 95% CI: 3.18-3.75, triple-negative and HER2-/HR+ tumours). After a 30-month follow-up, median OS after CNS metastasis diagnosis was 7.9 months (95% CI: 7.2-8.4). OS was independently associated with subtypes: median OS was 18.9 months (HR = 0.57, 95% CI: 0.50-0.64) for HER2+/HR+ , 13.1 months (HR = 0.72, 95% CI: 0.65-0.81) for HER2+/HR-, 4.4 months (HR = 1.55, 95% CI: 1.42-1.69) for triple-negative and 7.1 months for HER2-/HR+ patients (p <0.0001).

CONCLUSIONS

Tumour molecular subtypes strongly impact incidence, kinetics and prognosis of CNS metastases in MBC patients.

CLINICAL TRIAL REGISTRATION

NCT03275311.

A Comparison of DNA Mutation and Copy Number Profiles of Primary Breast Cancers and Paired Brain Metastases for Identifying Clinically Relevant Genetic Alterations in Brain Metastases

Improving the systemic treatment of brain metastases (BM) in primary breast cancer (PBC) is impaired by the lack of genomic characterization of BM. To estimate the concordance of DNA copy-number-alterations (CNAs), mutations, and actionable genetic alterations (AGAs) between paired samples, we performed whole-genome array-comparative-genomic-hybridization, and targeted-next-generation-sequencing on 14 clinical PBC–BM pairs. We found more CNAs, more mutations, and higher tumor mutational burden, and more AGAs in BM than in PBC; 92% of the pairs harbored at least one AGA in the BM not observed in the paired PBC. This concerned various therapeutic classes, including tyrosine-kinase-receptor-inhibitors, phosphatidylinositol 3-kinase/AKT/ mammalian Target of Rapamycin (PI3K/AKT/MTOR)-inhibitors, poly ADP ribose polymerase (PARP)-inhibitors, or cyclin-dependent kinase (CDK)-inhibitors. With regards to the PARP-inhibitors, the homologous recombination defect score was positive in 79% of BM, compared to 43% of PBC, discordant in 7 out of 14 pairs, and positive in the BM in 5 out of 14 cases. CDK-inhibitors were associated with the largest percentage of discordant AGA appearing in the BM. When considering the AGA with the highest clinical-evidence level, for each sample, 50% of the pairs harbored an AGA in the BM not detected or not retained from the analysis of the paired PBC. Thus, the profiling of BM provided a more reliable opportunity, than that of PBC, for diagnostic decision-making based on genomic analysis. Patients with BM deserve an investigation of several targeted therapies.

Targeting Molecular Pathways in Intracranial Metastatic Disease

The discovery and clinical application of agents targeting pivotal molecular pathways in malignancies such as lung, breast, renal cell carcinoma, and melanoma have led to impressive improvements in clinical outcomes. Mutations in epidermal growth factor receptor (EGFR), and rearrangements of anaplastic lymphoma kinase (ALK) are targetable in lung cancer, while BRAF mutations have been successfully targeted in metastatic melanoma. Targeting estrogen receptors, cyclin dependent kinases, and HER2 (Human Epidermal Receptor) have resulted in improvement in survival in breast cancer. Major strides have been made in the management of metastatic renal cell carcinoma by targeting the vascular endothelial growth factor (VEGF) pathway. However, intracranial metastases remain a major hurdle in the setting of targeted therapies. Traditional treatment options for brain metastases include surgery, whole brain radiation therapy (WBRT), and stereotactic radiosurgery (SRS). Surgery is effective in symptomatic patients with dominant lesions or solitary intracranial metastases, however, recovery time can be prolonged, often requiring an interruption in systemic treatment. WBRT and SRS provide symptomatic relief and local control but data on improving overall survival is limited. Most targeted therapies which provide extracranial control have limited penetration through the blood brain barrier. Given the limited therapeutic options and increasing prevalence of brain metastases, finding new strategies for the management of intracranial metastatic disease is critical. Genomic analysis of brain metastases has led to a better understanding of variations in the driver mutations compared to the primary malignancy. Furthermore, newer generations of targeted agents have shown promising intracranial activity. In this review, we will discuss the major molecular alterations in brain metastases from melanoma, lung, breast, and renal cell carcinoma. We will provide an in-depth review of the completed and ongoing clinical trials of drugs targeting the molecular pathways enriched in brain metastases.

Leptomeningeal carcinomatosis in patients with breast cancer

Leptomeningeal carcinomatosis (LC) is defined as infiltration of the leptomeninges by metastatic carcinoma, a relatively uncommon but devastating complication of many malignancies. Although only 5% of patients with breast cancer develop leptomeningeal involvement, it remains the most common etiology of LC. It can occur as a late-stage complication of systemic progression or present as the first sign of metastatic disease, with or without parenchymal brain metastases. Lobular carcinomas have a higher propensity to metastasize into the meninges when compared to ductal carcinoma, especially the triple-negative subtype, which usually is associated with a shorter interval between metastatic breast cancer diagnosis and the development of LC. Prognosis remains poor, with median survival of 4 months for patients receiving state-of-the-art treatment. The main factors associated with survival are performance status at diagnosis, CSF protein level and triple-negative subtype. Headache is commonly the first clinical presentation of LC, and the diagnostic workup usually requires CSF-cytological analysis and or/MRI. The current management of LC consists of a combination of intra-CSF chemotherapy, systemic therapy, radiotherapy and/or best-supportive care. The standard intra-CSF chemotherapy regimen is methotrexate. Radiotherapy is used for relieving obstruction points on CSF-outflow channels due to ependymal nodules, tumor deposits or bulky disease. Objective responses have been reported with intrathecal administration of trastuzumab for HER2-positive disease, yet this strategy is still under investigation. Further prospective trials are needed to better address the impact of these treatment modalities on overall survival and quality of life.

Improving orthotopic mouse models of patient-derived breast cancer brain metastases by a modified intracarotid injection method

Breast cancer brain metastasis (BCBM) remains a major clinical problem. Approximately 10–16% of patients with breast cancer develop brain metastases (BCBM). However, no systemic therapy has gained regulatory approval for the specific treatment of BCBM and this remains an area of persistent, unmet medical need. Rapid, predictive and clinically-relevant animal models are critical to study the biology of brain metastases and to identify effective therapeutic approaches for patients with BCBM. Here, we describe a method for efficient establishment of orthotopic mouse models of patient-derived brain metastases via an improved intracarotid injection protocol that permits tumor cell growth in the unique brain microenvironment without compromising the blood-brain barrier (BBB). We demonstrate that our newly improved models of patient-derived brain metastases recapitulate the histologic, molecular, and genetic characteristics of their matched patient tumor specimens and thus represent a potentially powerful tool for pre-clinical and translational research.

Brain Metastases

Brain metastases from solid tumors are associated with increased morbidity and mortality. Standard treatment is local therapy with surgery and/or radiation therapy although there is increasing interest in systemic therapies that can control both intracranial and extracranial disease. We review the most recent data for local therapy and systemic therapy options. Active areas of research within radiation oncology include hippocampal sparing whole brain radiation therapy and stereotactic approaches for patients with more than 4 brain metastases. Newer targeted therapies with better central nervous system penetration and immunotherapies have demonstrated promising results in clinical trials of patients with brain metastases.