Systemic therapy of brain metastases

Using Radiomics to Differentiate Brain Metastases From Lung Cancer Versus Breast Cancer, Including Predicting Epidermal Growth Factor Receptor and human Epidermal Growth Factor Receptor 2 Status

OBJECTIVE

We evaluated the feasibility of using multiregional radiomics to identify brain metastasis (BM) originating from lung adenocarcinoma (LA) and breast cancer (BC) and assess the epidermal growth factor receptor (EGFR) mutation and human epidermal growth factor receptor 2 (HER2) status.

METHODS

Our experiment included 160 patients with BM originating from LA (n = 70), BC (n = 67), and other tumor types (n = 23), between November 2017 and December 2021. All patients underwent contrast-enhanced T1- and T2-weighted magnetic resonance imaging (MRI) scans. A total of 1967 quantitative MRI features were calculated from the tumoral active area and peritumoral edema area and selected using least absolute shrinkage and selection operator regression with 5-fold cross-validation. We constructed radiomic signatures (RSs) based on the most predictive features for preoperative assessment of the metastatic origins, EGFR mutation, and HER2 status. Prediction performance of the constructed RSs was evaluated based on the receiver operating characteristic curve analysis.

RESULTS

The developed multiregion RSs generated good area under the receiver operating characteristic curve (AUC) for identifying the LA and BC origin in the training (AUCs, RS-LA vs RS-BC, 0.767 vs 0.898) and validation (AUCs, RS-LA vs RS-BC, 0.778 and 0.843) cohort and for predicting the EGFR and HER2 status in the training (AUCs, RS-EGFR vs RS-HER2, 0.837 vs 0.894) and validation (AUCs, RS-EGFR vs RS-HER2, 0.729 vs 0.784) cohorts.

CONCLUSIONS

Our results revealed associations between brain MRI-based radiomics and their metastatic origins, EGFR mutations, and HER2 status. The developed multiregion combined RSs may be considered noninvasive predictive markers for planning early treatment for BM patients.

Trastuzumab deruxtecan in HER2-positive breast cancer with brain metastases: a single-arm, phase 2 trial

Trastuzumab deruxtecan is an antibody–drug conjugate with high extracranial activity in human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. We conducted the prospective, open-label, single-arm, phase 2 TUXEDO-1 trial. We enrolled patients aged ≥18 years with HER2-positive breast cancer and newly diagnosed untreated brain metastases or brain metastases progressing after previous local therapy, previous exposure to trastuzumab and pertuzumab and no indication for immediate local therapy. Patients received trastuzumab deruxtecan intravenously at the standard dose of 5.4 mg per kg bodyweight once every 3 weeks. The primary endpoint was intracranial response rate measured according to the response assessment in neuro-oncology brain metastases criteria. A Simon two-stage design was used to compare a null hypothesis of <26% response rate against an alternative of 61%. Fifteen patients were enrolled in the intention-to-treat population of patients who received at least one dose of study drug. Two patients (13.3%) had a complete intracranial response, nine (60%) had a partial intracranial response and three (20%) had stable disease as the best intracranial response, with a best overall intracranial response rate of 73.3% (95% confidential interval 48.1–89.1%), thus meeting the predefined primary outcome. No new safety signals were observed and global quality-of-life and cognitive functioning were maintained over the treatment duration. In the TUXEDO-1 trial (NCT04752059, EudraCT 2020-000981-41), trastuzumab deruxtecan showed a high intracranial response rate in patients with active brain metastases from HER2-positive breast cancer and should be considered as a treatment option in this setting.

Findings from the TUXEDO-1 trial demonstrate efficacy of the antibody–drug conjugate trastuzumab deruxtecan for treatment of brain metastases in patients with HER2-positive breast cancer.

A deep learning approach with subregion partition in MRI image analysis for metastatic brain tumor

Purpose

To propose a deep learning network with subregion partition for predicting metastatic origins and EGFR/HER2 status in patients with brain metastasis.

Methods

We retrospectively enrolled 140 patients with clinico-pathologically confirmed brain metastasis originated from primary NSCLC (n = 60), breast cancer (BC, n = 60) and other tumor types (n = 20). All patients underwent contrast-enhanced brain MRI scans. The brain metastasis was subdivided into phenotypically consistent subregions using patient-level and population-level clustering. A residual network with a global average pooling layer (RN-GAP) was proposed to calculate deep learning-based features. Features from each subregion were selected with least absolute shrinkage and selection operator (LASSO) to build logistic regression models (LRs) for predicting primary tumor types (LR-NSCLC for the NSCLC origin and LR-BC for the BC origin), EGFR mutation status (LR-EGFR) and HER2 status (LR-HER2).

Results

The brain metastasis can be partitioned into a marginal subregion (S1) and an inner subregion (S2) in the MRI image. The developed models showed good predictive performance in the training (AUCs, LR-NSCLC vs. LR-BC vs. LR-EGFR vs. LR-HER2, 0.860 vs. 0.909 vs. 0.850 vs. 0.900) and validation (AUCs, LR-NSCLC vs. LR-BC vs. LR-EGFR vs. LR-HER2, 0.819 vs. 0.872 vs. 0.750 vs. 0.830) set.

Conclusion

Our proposed deep learning network with subregion partitions can accurately predict metastatic origins and EGFR/HER2 status of brain metastasis, and hence may have the potential to be non-invasive and preoperative new markers for guiding personalized treatment plans in patients with brain metastasis.

Stereotactic radiotherapy or metastasectomy for oligometastatic esophagogastric cancer: a nationwide population-based cohort study

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This nationwide study included patients with esophagogastric cancer and OMD.

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Local treatment of OMD was associated with improved OS.

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Local treatment of OMD plus systemic therapy was associated with better OS.

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Randomized trials are warranted to conform results.

Background and purpose

This nationwide population-based study analyzed the outcomes of local treatment (i.e. stereotactic body radiotherapy [SBRT] or metastasectomy) or systemic therapy for oligometastatic disease (OMD) in patients with esophagogastric cancer in The Netherlands.

Materials and methods

Between 2015 and 2016, all patients in The Netherlands with esophagogastric cancer and synchronous or metachronous OMD were eligible for inclusion. Patients who underwent local treatment of OMD (SBRT or metastasectomy) and/or systemic therapy were included. OMD was defined as distant metastases in 1 organ or 1 extra-regional lymph node region. The primary outcomes were overall survival (OS) and independent prognostic factors for OS. OS was calculated from diagnosis of OMD. Prognostic factors for OS were analyzed using a multivariable Cox proportional hazard model.

Results

A total of 594 patients were included, of whom 83 underwent local treatment for OMD alone, 22 local treatment plus systemic therapy, and 489 systemic therapy alone. Median OS after local treatment for OMD alone was 16.0 months, local treatment plus systemic therapy 22.7 months, and after systemic therapy alone 8.5 months. Improved OS was independently associated with local treatment for OMD alone or combined with systemic therapy as compared with systemic therapy alone (hazard ratio [HR] 0.52, 95% CI: 0.31–0.90 and HR 0.42, 95% CI: 0.22-0.82, respectively) and a controlled primary tumor(HR 0.48, 95% CI: 0.27–0.86). Worse OS was independently associated with worse performance scores (HR 1.41, 95%: 1.32-1.75), poorly or undiffertumor as compared with good or moderadifferentiated tumor (HR 1.37, 95% CI: 1.06-1.76), and peritoneal as compared with lymph mode metastases (HR 1.39, 95% CI: 1.00-1.93).

Conclusion

Local treatment of OMD alone or combined with systemic therapy was independently associated with improved OS as compared with systemic therapy alone in this population-based cohort study in The Netherlands. Randomized controlled trials are warranted to confirm these results.

Cross-sectional survey of patients, caregivers, and physicians on diagnosis and treatment of brain metastases

BACKGROUND

The development of brain metastases (BM) is one of the most feared complications of cancer due to the substantial neurocognitive morbidity and a grim prognosis. In the past decade, targeted therapies and checkpoint inhibitors have demonstrated promising intracranial response rates for tumors of multiple histologies. As overall survival for these patients improves, there is a growing need to identify issues surrounding patient survivorship and to standardize physician practice patterns for these patients. To date, there has not been an adequate study to specifically explore these questions of survivorship and practice standardization for patients with advanced cancer and BM.

METHODS

Here, we present results from a cross-sectional survey in which we analyze responses from 237 patients, 209 caregivers, and 239 physicians to identify areas of improvement in the clinical care of BM.

RESULTS

In comparing physician and patient/caregiver responses, we found a disparity in the perceived discussion of topics pertaining to important aspects of BM clinical care. We identified variability in practice patterns for this patient population between private practice and academic physicians. Many physicians continue to have patients with BM excluded from clinical trials. Finally, we obtained patient/physician recommendations on high-yield areas for federal funding to improve patient quality of life.

CONCLUSION

By identifying potential areas of unmet need, we anticipate this wealth of actionable information will translate into tangible benefits for both patients and caregivers. Future studies are needed to validate our findings.

Safety and Efficacy of the Combination of Nivolumab Plus Ipilimumab in Patients With Melanoma and Asymptomatic or Symptomatic Brain Metastases (CheckMate 204)

Background

In patients with melanoma and asymptomatic brain metastases (MBM), nivolumab plus ipilimumab provided an intracranial response rate of 55%. Here, we present the first report for patients who were symptomatic and/or required corticosteroids and updated data for asymptomatic patients.

Methods

Patients with measurable MBM, 0.5-3.0 cm, were enrolled into Cohort A (asymptomatic) or Cohort B (stable neurologic symptoms and/or receiving corticosteroids). Nivolumab, 1 mg/kg, and ipilimumab, 3 mg/kg, were given intravenously every 3 weeks ×4, followed by nivolumab, 3 mg/kg, every 2 weeks until progression, unacceptable toxicity, or 24 months. The primary endpoint was intracranial clinical benefit rate (CBR; complete response [CR], partial response [PR], or stable disease ≥6 months).

Results

Symptomatic patients (N = 18) received a median of one nivolumab and ipilimumab combination dose and had an intracranial CBR of 22.2%. Two of 12 patients on corticosteroids had CR; 2 responded among the 6 not on corticosteroids. Median intracranial progression-free survival (PFS) and overall survival (OS) were 1.2 and 8.7 months, respectively. In contrast, with 20.6 months of follow-up, we confirmed an intracranial CBR of 58.4% in asymptomatic patients (N = 101); median duration of response, PFS, and OS were not reached. No new safety signals were observed.

Conclusions

Nivolumab plus ipilimumab provides durable clinical benefit for asymptomatic patients with MBM and should be considered for first-line therapy. This regimen has limited activity in MBM patients with neurologic symptoms and/or requiring corticosteroids, supporting the need for alternative approaches and methods to reduce the dependency on corticosteroids.

Clinical trial registration. ClinicalTrials.gov, NCT02320058.

Trastuzumab-deruxtecan: an investigational agent for the treatment of HER2-positive breast cancer

INTRODUCTION

The prognosis of patients with HER2-positive breast cancer was dramatically changed by the introduction of targeted therapies. With trastuzumab, pertuzumab, and T-DM1 widely used as (neo)adjuvant therapy today, novel treatment options are required to optimize treatment of HER2-positive metastatic disease. Trastuzumab-deruxtecan is an antibody-drug conjugate (ADC) consisting of a monoclonal humanized immunoglobulin G1 antibody, a linker molecule, and the exatecan derivative DXd. T-DXd has a higher drug to antibody ratio compared with T-DM1; in addition, membrane permeability of DXd is high, resulting in an increased bystander effect. Results from early clinical development suggest a clinically relevant activity of T-DXd in heavily pretreated patients with HER2-positive metastatic breast cancer progressing on T-DM1. Interstitial lung disease was a side-effect requiring special attention and was observed in approximately 13% of patients.

AREAS COVERED

This article reviews preclinical and clinical data on T-DXd. A systematic literature search was performed to identify relevant publications. The search included original research articles, abstracts from major conferences, and reviews and was limited to English-language publications.

EXPERT OPINION

T-DXd is an efficacious and tolerable drug and harbors promise as a key addition to the therapeutic field in HER2-positive breast cancer.

Evaluating Magnetic Resonance Spectroscopy as a Tool for Monitoring Therapeutic Response of Whole Brain Radiotherapy in a Mouse Model for Breast-to-Brain Metastasis

Brain metastases are the most common intracranial tumor in adults and are associated with poor patient prognosis and median survival of only a few months. Treatment options for brain metastasis patients remain limited and largely depend on surgical resection, radio- and/or chemotherapy. The development and pre-clinical testing of novel therapeutic strategies require reliable experimental models and diagnostic tools that closely mimic technologies that are used in the clinic and reflect histopathological and biochemical changes that distinguish tumor progression from therapeutic response. In this study, we sought to test the applicability of magnetic resonance (MR) spectroscopy in combination with MR imaging to closely monitor therapeutic efficacy in a breast-to-brain metastasis model. Given the importance of radiotherapy as the standard of care for the majority of brain metastases patients, we chose to monitor the post-irradiation response by magnetic resonance spectroscopy (MRS) in combination with MR imaging (MRI) using a 7 Tesla small animal scanner. Radiation was applied as whole brain radiotherapy (WBRT) using the image-guided Small Animal Radiation Research Platform (SARRP). Here we describe alterations in different metabolites, including creatine and N-acetylaspartate, that are characteristic for brain metastases progression and lactate, which indicates hypoxia, while choline levels remained stable. Radiotherapy resulted in normalization of metabolite levels indicating tumor stasis or regression in response to treatment. Our data indicate that the use of MR spectroscopy in addition to MRI represents a valuable tool to closely monitor not only volumetrical but also metabolic changes during tumor progression and to evaluate therapeutic efficacy of intervention strategies. Adapting the analytical technology in brain metastasis models to those used in clinical settings will increase the translational significance of experimental evaluation and thus contribute to the advancement of pre-clinical assessment of novel therapeutic strategies to improve treatment options for brain metastases patients.

Precision Medical Approaches to the Diagnoses and Management of Brain Metastases

OPINION STATEMENT

Brain metastases represent a common and devastating complication of cancer with survival on the order of a few months in most patients. Melanoma, breast cancer, and lung cancer remain the primary disease histologies with the highest rates of metastatic spread to the brain. The incidence of brain metastases has continued to rise, likely explained by multiple factors. Improvement in progression-free survival in systemic cancer is likely attributable to advances in medical therapy, earlier supportive and symptomatic care, and improved precision around diagnosis and detection. In this context, longer survival and improved extracranial control disease has likely contributed to the increased development of metastatic spread intracranially. The foundation of management remains systemic therapy, as well as a combination of surgery and radiation therapy. In the era of targeted therapies, specific agents have demonstrated improved CNS penetration, however with varying degrees of durable responses. Most patients develop resistance to targeted agents, limiting their duration of use for patients. In this era of personalized medicine, the role of genomic characterization in cancer has been critical in the field of brain metastases, as alterations unique to both the brain metastases and its systemic predecessor have been identified, potentially offering new avenues for therapy.

Upfront Surgical Resection of Melanoma Brain Metastases Provides a Bridge Toward Immunotherapy-Mediated Systemic Control

BACKGROUND

Immune checkpoint blockade has systemic efficacy in patients with metastatic melanoma, including those with brain metastases (MBMs). However, immunotherapy-induced intracranial tumoral inflammation can lead to neurologic compromise, requiring steroids, which abrogate the systemic efficacy of this approach. We investigated whether upfront neurosurgical resection of MBM is associated with a therapeutic advantage when performed prior to initiation of immunotherapy.

MATERIAL AND METHODS

An institutional review board-approved, retrospective study identified 142 patients with MBM treated with immune checkpoint blockade between 2010 and 2016 at Massachusetts General Hospital, of whom 79 received surgery. Patients were classified based on the temporal relationship between immunotherapy, surgery, and development of central nervous system metastases. Overall survival (OS) was calculated from the date of diagnosis of MBM until death from any cause. Multivariate model building included a prognostic Cox model of OS, the effect of immunotherapy and surgical sequencing on OS, and the effect of immunotherapy and radiation sequencing on OS.

RESULTS

The 2-year overall survival for patients treated with cytotoxic T-lymphocyte antigen 4, programmed death 1, or combinatorial blockade was 19%, 54%, and 57%, respectively. Among immunotherapy-naïve melanoma brain metastases, surgery followed by immunotherapy had a median survival of 22.7 months (95% confidence interval [CI], 12.6-39.2) compared with 10.8 months for patients treated with immunotherapy alone (95% CI, 7.8-16.3) and 9.4 months for patients treated with immunotherapy followed by surgery (95% CI, 4.1 to ∞; p = .12). On multivariate analysis, immunotherapy-naïve brain metastases treated with immunotherapy alone were associated with increased risk of death (hazard ratio, 1.72; 95% CI, 1.00-2.99) compared with immunotherapy-naïve brain metastases treated with surgery followed by immunotherapy.

CONCLUSION

In treatment-naïve patients, early surgical resection for local control should be considered prior to commencing immunotherapy. A prospective, randomized trial comparing the sequence of surgery and immunotherapy for treatment-naïve melanoma brain metastases is warranted.

IMPLICATIONS FOR PRACTICE

In this retrospective study of 142 patients with melanoma brain metastases treated with immune checkpoint blockade, the development of melanoma brain metastases following immunotherapy was associated with decreased survival compared with diagnosis of immunotherapy-naïve brain metastases. The benefit of surgical intervention was seen in immunotherapy-naïve brain metastases in contrast to brain metastases that developed on immunotherapy. These results suggest that upfront local control with surgery for immunotherapy-naïve melanoma brain metastasis may provide a bridge toward immunotherapy-mediated systemic control.

Prophylactic TLR9 stimulation reduces brain metastasis through microglia activation

Brain metastases are prevalent in various types of cancer and are often terminal, given the low efficacy of available therapies. Therefore, preventing them is of utmost clinical relevance, and prophylactic treatments are perhaps the most efficient strategy. Here, we show that systemic prophylactic administration of a toll-like receptor (TLR) 9 agonist, CpG-C, is effective against brain metastases. Acute and chronic systemic administration of CpG-C reduced tumor cell seeding and growth in the brain in three tumor models in mice, including metastasis of human and mouse lung cancer, and spontaneous melanoma-derived brain metastasis. Studying mechanisms underlying the therapeutic effects of CpG-C, we found that in the brain, unlike in the periphery, natural killer (NK) cells and monocytes are not involved in controlling metastasis. Next, we demonstrated that the systemically administered CpG-C is taken up by endothelial cells, astrocytes, and microglia, without affecting blood-brain barrier (BBB) integrity and tumor brain extravasation. In vitro assays pointed to microglia, but not astrocytes, as mediators of CpG- C effects through increased tumor killing and phagocytosis, mediated by direct microglia-tumor contact. In vivo, CpG-C-activated microglia displayed elevated mRNA expression levels of apoptosis-inducing and phagocytosis-related genes. Intravital imaging showed that CpG-C-activated microglia cells contact, kill, and phagocytize tumor cells in the early stages of tumor brain invasion more than nonactivated microglia. Blocking in vivo activation of microglia with minocycline, and depletion of microglia with a colony-stimulating factor 1 inhibitor, indicated that microglia mediate the antitumor effects of CpG-C. Overall, the results suggest prophylactic CpG-C treatment as a new intervention against brain metastasis, through an essential activation of microglia.

Stereotactic Radiosurgery for Multiple Brain Metastases

PURPOSE OF REVIEW

To give an overview on the current evidence for stereotactic radiosurgery of brain metastases with a special focus on multiple brain metastases.

RECENT FINDINGS

While the use of stereotactic radiosurgery in patients with limited brain metastases has been clearly defined, its role in patients with multiple lesions (> 4) is still a matter of controversy. Whole-brain radiation therapy (WBRT) has been the standard treatment approach for patients with multiple brain lesions and is still the most commonly used treatment approach worldwide. Although distant brain failure is improved by WBRT, the overall survival is not readily impacted. As WBRT is associated with significant neurocognitive decline compared to stereotactic radiosurgery (SRS), SRS has been explored and increasingly utilized for selected patients with multiple brain metastases. Recent clinical data indicated the feasibility of stereotactic radiosurgery to multiple brain metastases with a similar survival in patients with more than 4 brain metastases versus patients with a maximum of 4 brain metastases. Also, neurocognitive function and quality of life was maintained after stereotactic radiosurgery which is essential in a palliative setting. The application of stereotactic radiosurgery with Gamma Knife, Cyberknife, or LINAC-based equipment has emerged as an effective and widely available treatment option for patients with limited brain metastases. Although not formally proven in prospective studies, SRS may also be considered as a safe and effective treatment option in selected patients with multiple brain metastases. Especially in patients with a favorable prognosis, survival over several years is observed also in the setting of multiple BM. For these patients, avoidance of the neurocognitive damage of WBRT is desirable, and SRS is often a more appropriate treatment in the current multimodality treatment of BM in which systemic treatment is often the cornerstone of the treatment. For patients with an intermediate (3-12 months) and poor prognosis (< 3 months), the application of WBRT becomes more and more controversial, because of its acute side effects, such as hair loss and fatigue and, thereby, detrimental effect on quality of life. For these patients, best supportive care, primary systemic treatment, and even SRS may be preferred over WBRT on an individualized patient basis.

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.

New developments in brain metastases

Patients with brain metastases (BM) are a population of high clinical need for new therapeutic approaches due to, as yet, very impaired survival prognosis. However, only few clinical trials have specifically addressed this prognostically highly heterogeneous patient population. New developments in the treatment of BM patients aim to reduce the side effects of local therapies, for example, by redefining the indications for stereotactic radiosurgery and whole-brain radiotherapy (WBRT) or introducing new applications like hippocampal sparing WBRT. Furthermore, systemic therapies become a more important treatment approach in patients harboring targetable mutations, as recent BM-specific endpoints in several phase III trials have shown promising intracranial efficacy. In addition, immune-checkpoint inhibitors show promising intracranial efficacy, particularly in patients with melanoma and non-small lung cancer BM. Here, we provide a review on the recent new developments in the local and systemic therapy approaches in BM patients.

Targeted DNA sequencing of non-small cell lung cancer identifies mutations associated with brain metastases

Introduction

This study explores the hypothesis that dominant molecular oncogenes in non-small cell lung cancer (NSCLC) are associated with metastatic spread to the brain.

Methods

NSCLC patient groups with no evidence of metastasis, with metastatic disease to a non-CNS site, who developed brain metastasis after diagnosis, and patients with simultaneous diagnosis of NSCLC and metastatic brain lesions were studied using targeted sequencing.

Results

In patients with brain metastasis versus those without, only 2 variants (one each in BCL6 and NOTHC2) were identified that occurred in ≥ 4 NSCLC of patients with brain metastases but ≤ 1 of the NSCLC samples without brain metastases. At the gene level, 20 genes were found to have unique variants in more than 33% of the patients with brain metastases. When analyzed at the patient level, these 20 genes formed the basis of a predictive test to discriminate those with brain metastasis. Further analysis showed that PI3K/AKT signaling is altered in both the primary and metastases of NSCLC patients with brain lesions.

Conclusion

While no single variant was associated with brain metastasis, this study describes a potential gene panel for the identification of patients at risk and implicates PI3K/AKT signaling as a therapeutic target.

Overview of metastatic disease of the central nervous system

In 2016, the American Society of Clinical Oncology reported that 1.7 million Americans were diagnosed with cancer; this number will rise to 2.3 million in the United States and 22 million worldwide in 2030. This rising need is being met by an explosion of new cancer therapies, including: immune checkpoint inhibitors, T-cell therapies, tumor vaccines, antiangiogenic therapies, and various targeted therapies. This armamentarium of targeted therapies has led to better systemic control of disease and longer patient overall survival (OS). The incidence of metastatic disease to the central nervous system (CNS) is rising as patients are living longer with these more effective systemic therapies. Prolonged OS allows increased time to develop CNS metastases. The CNS is also a sanctuary for metastatic tumor cells that are protected from full exposure to therapeutic concentrations of most anticancer agents by the blood-brain barrier, the tumor microenvironment, and immune system. In addition, CNS metastases often develop late in the course of the disease, so patients are frequently heavily pretreated, resulting in drug resistance. Although genomic profiling has led to more effective therapies for systemic disease, the same therapy may not be effective in treating CNS disease, not only due to failure of blood-brain barrier penetration, but from discordance between the molecular profile in systemic and CNS tumor.

Management of Brain Metastases in Patients With Melanoma

Melanoma is the third most common systemic cancer that leads to brain metastases. The annual incidence of melanoma has increased over time, with brain metastases developing in 40% to 50% of patients with advanced melanoma. Traditional management of melanoma-related brain metastases has focused on symptom control as a result of the significant neurologic morbidity associated with the disease. Median overall survival for these patients, if untreated, is approximately 3 months. As with other brain metastases, a multidisciplinary treatment approach that includes surgery and radiation therapy is typically used, with historically little role for systemic, cytotoxic therapy. During the past decade, advancement within the field of genomics has led to the identification of melanoma-specific mutations, namely, v-Raf murine sarcoma viral oncogene homolog B and neuroblastoma RAS viral oncogene homolog, as well as to the development of agents that target these driver mutations. In addition, the advent of immunotherapies, specifically, agents that target cytotoxic T-lymphocyte antigen-4, anti-programmed death-1, and programmed death ligand-1, has increased the potential therapeutic options available to patients with both systemic and brain disease. With these advances, early trials have demonstrated improved overall survival in patients with brain metastases who receive these therapies either as single agents or as part of multimodality treatment regimens.

The effect of regadenoson on the integrity of the human blood-brain barrier, a pilot study

Regadenoson is an FDA approved adenosine receptor agonist which increases blood-brain barrier (BBB) permeability in rodents. Regadenoson is used clinically for pharmacologic cardiac stress testing using SPECT or CT imaging agents that do not cross an intact BBB. This study was conducted to determine if standard doses of regadenoson transiently disrupt the human BBB allowing higher concentrations of systemically administered imaging agents to enter the brain. Patients without known intracranial disease undergoing clinically indicated pharmacologic cardiac stress tests were eligible for this study. They received regadenoson (0.4 mg) followed by brain imaging with either ^99mTc-sestamibi for SPECT or visipaque for CT imaging. Pre- and post-regadenoson penetration of imaging agents into brain were quantified [SPECT: radioactive counts, CT: Hounsfield units (HU)] and compared using a matched-pairs t-test. Twelve patients (33% male, median 60 yo) were accrued: 7 SPECT and 5 CT. No significant differences were noted in pre- and post-regadenoson values using mean radionuclide counts (726 vs. 757) or HU (29 vs. 30). While animal studies have demonstrated that regadenoson transiently increases the permeability of the BBB to dextran and temozolomide, we were unable to document changes in the penetration of contrast agents in humans with intact BBB using the FDA approved doses of regadenoson for cardiac evaluation. Further studies are needed exploring alternate regadenoson dosing, schedules, and studies in patients with brain tumors; as transiently disrupting the BBB to improve drug entry into the brain is critical to improving the care of patients with CNS malignancies.

Sequencing brain metastases and opportunities for targeted therapies

CNS metastases have long been recognized as a common and late complication of systemic malignancies. They represent the most common tumor of the brain. As outcomes and overall survival improve with better tolerated and more durable responses from therapies for systemic cancers, the incidence and prevalence of brain metastases is likely to increase. Among the most common systemic cancers leading to brain metastases include lung, melanoma, breast (triple-negative histology) and renal cell cancers. To date, there has been infrequent involvement of gastrointestinal and gynecologic malignancies; however, this may also change, reflecting improvement in overall survival and therapeutic regimens. Traditional therapy of brain metastases has focused on surgery, radiation therapy or best supportive/palliative care. The advent of modern genomic techniques, including next-generation and whole-exome sequencing, has allowed for the identification of unique markers and potential drivers of metastatic pathways. This review aims to discuss and highlight the known drivers of disease and the opportunities for ultimate development of targeted therapies.

Quality of Life following Stereotactic Radiosurgery for Single and Multiple Brain Metastases

BACKGROUND: Given the neurological morbidity and poor prognosis associated with brain metastases, it is critical to deliver appropriate therapy while remaining mindful of patient quality of life (QOL). For many patients, stereotactic radiosurgery (SRS) effectively controls intracranial disease, but QOL outcomes have not been characterized.

OBJECTIVE: To determine the effect of number of brain metastases upon QOL preservation following SRS.

METHODS: The EuroQol 5 Dimensions questionnaire (EQ-5D) and Patient Health Questionnaire 9 instruments were prospectively collected from a cohort of patients undergoing SRS for brain metastasis between 2008 and 2015. These instruments served as measures of overall QOL and depression. QOL deterioration exceeding the minimum clinically important difference was considered failure. Freedom from 12-month EQ-5D index failure was the primary outcome.

RESULTS: One hundred and twenty-two SRS treatments (67 patients, 421 lesions) were eligible for inclusion. Intracranial failure (local or distant) occurred following 61% of treatments. Among 421 lesions, 8% progressed locally. Median follow-up was 12 months.

All subscores of the EQ-5D instrument expectantly worsened at last follow-up; however, the magnitude of this difference (0.079) did not exceed the EQ-5D index minimum clinically important difference (mean 0.752 vs 0.673, P &lt; .01). Twelve-month EQ-5D index QOL preservation was 79%. Patients with more than 3 brain metastases had a greater rate of EQ-5D index deterioration (hazard ratio 4.14, P &lt; .01) than those with a single metastasis.

CONCLUSIONS: Among patients with brain metastasis, QOL preservation must remain paramount as multimodality therapy continues to improve. In the present investigation, 12-month QOL preservation was 79%. However, patients with more than 3 brain metastases were at significantly greater risk for QOL decline.

Cancer and the metastatic substrate

Seventy percent of cancer patients have detectable metastases when they receive a diagnosis and 90% of cancer deaths result from metastases. These two facts emphasise the urgency for research to study the mechanisms and processes that enable metastasis. We need to develop a greater understanding of the cellular and molecular mechanisms that cause metastasis and also we need to do more. We must also consider the micro- and macro-environmental factors that influence this disease. Studying this environmental context has led us to update the ‘seed and soil’ hypothesis which dates back to the 19th century. This theory describes cancerous cells as seeds and the substrate as the soil in target organs though this may seem antiquated. Nonetheless, the tissue specificity that researchers have recently observed in metastatic colonisation supports the validity of the seed and soil theory. We now know that the metastatic potential of a tumour cell depends on multiple, reciprocal interactions between the primary tumour and distant sites. These interactions determine tumour progression. Studies of metastasis have allowed us to develop treatments that focus on therapeutic effectiveness. These new treatments account for the frequent metastasis of some tumours to target organs such as bones, lungs, brain, and liver. The purpose of this review is first to describe interactions between the cellular and molecular entities and the target organ tumour environment that enables metastasis. A second aim is to describe the complex mechanisms that mediate these interactions.

Treatment of brain metastases

BACKGROUND

Brain metastases are a very common neurological sequela in cancer patients. The ability of current anti-cancer therapies to prolong overall survival is beleaguered by this development in the case of a number of different cancers. This review provides a general overview of relevant treatment modalities, highlights major decision strategies used in selecting the optimal treatment algorithm and summarizes important steps necessary before initiating therapy.

METHODS

A PubMed database search was done to identify publications describing the treatment of brain metastases including surgery, radiotherapy and symptomatic care.

RESULTS AND CONCLUSION

Patient performance status and extent of disease play the most important roles in selecting between an aggressive or more conservative approach. As several other options are available, treatment decisions should be made in cooperation with multiple medical specialties and the involvement of multidisciplinary teams. In the future, brain metastases could become less of a treatment obstacle than they are today.

The evolving clinical management of cerebral metastases

Concepts in the management of brain metastases are evolving. Until recently, brain metastases have been considered as a homogenous condition, managed with whole brain radiotherapy, surgical resection for large lesions and stereotactic radiosurgery for smaller lesions. Increasingly, specific systemic medical therapies are being used to treat brain metastases based on the primary site of disease. This disease specific management is causing a change in perspective about brain metastases and has led to improved survival for patients with primary disease subtypes amenable to tailored medical therapies. We review the recent literature to present evidence for the use of subtype specific medical therapies, advances in surgical resection techniques and stereotactic radiosurgery as the primary treatment modalities. The decline in use of whole brain radiotherapy as first line treatment is also discussed. Based on the recent literature, we propose a new management algorithm to reflect the progress in available options for tailoring disease specific treatments and support the change in paradigm to consider brain metastases as separate disease states based on the primary site of cancer rather than as a homogenous entity.

The future of targeted therapies for brain metastases

Brain metastases (BM) are an increasing challenge in the management of patients with advanced cancer. Treatment options for BM are limited and mainly focus on the application of local therapies. Systemic therapies including targeted therapies are only poorly investigated, as patients with BM were frequently excluded from clinical trials. Several targeted therapies have shown promising activity in patients with BM. In the present review we discuss existing and emerging targeted therapies for the most frequent BM primary tumor types. We focus on challenges in the conduction of clinical trials on targeted therapies in BM patients such as patient selection, combination with radiotherapy, the obstacles of the blood–brain barrier and the definition of study end points.