Strategies to Prevent Brain Metastasis in High-Risk Non–Small-Cell Lung Cancer: Lessons Learned From a Randomized Study of Maintenance Temozolomide Versus Observation

Genomic Alterations and the Incidence of Brain Metastases in Advanced and Metastatic NSCLC: A Systematic Review and Meta-Analysis

INTRODUCTION

Brain metastases (BMs) in patients with advanced and metastatic NSCLC are linked to poor prognosis. Identifying genomic alterations associated with BM development could influence screening and determine targeted treatment. We aimed to establish prevalence and incidence in these groups, stratified by genomic alterations.

METHODS

A systematic review and meta-analysis compliant with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses were conducted (PROSPERO identification CRD42022315915). Articles published in MEDLINE, EMBASE, and Cochrane Library between January 2000 and May 2022 were included. Prevalence at diagnosis and incidence of new BM per year were obtained, including patients with EGFR, ALK, KRAS, and other alterations. Pooled incidence rates were calculated using random effects models.

RESULTS

A total of 64 unique articles were included (24,784 patients with NSCLC with prevalence data from 45 studies and 9058 patients with NSCLC having incidence data from 40 studies). Pooled BM prevalence at diagnosis was 28.6% (45 studies, 95% confidence interval [CI]: 26.1-31.0), and highest in patients that are ALK-positive (34.9%) or with RET-translocations (32.2%). With a median follow-up of 24 months, the per-year incidence of new BM was 0.13 in the wild-type group (14 studies, 95% CI: 0.11-0.16). Incidence was 0.16 in the EGFR group (16 studies, 95% CI: 0.11-0.21), 0.17 in the ALK group (five studies, 95% CI: 0.10-0.27), 0.10 in the KRAS group (four studies, 95% CI: 0.06-0.17), 0.13 in the ROS1 group (three studies, 95% CI: 0.06-0.28), and 0.12 in the RET group (two studies, 95% CI: 0.08-0.17).

CONCLUSIONS

Comprehensive meta-analysis indicates a higher prevalence and incidence of BM in patients with certain targetable genomic alterations. This supports brain imaging at staging and follow-up, and the need for targeted therapies with brain penetrance.

Prophylactic cranial irradiation in non-small cell lung cancer: evidence and future development

In non-small cell lung cancer (NSCLC) brain metastases (BM) will affect up to 50% of patients during whole disease period. BM themselves impact heavily not only on patient’s prognosis but also are a source of symptoms aggravating quality of life. Standard (pemetrexed), and non-standard chemotherapy (temozolomide) in patients with NSCLC failed to prevent them from BM. In terms of systemic treatment there are promising results showed when durvalumab (PACIFIC study), osimertinib (FLAURA trial) or alectinib (JALEX study) was used. However, those substances are effective only in small cohort with ALK or EGFR alterations. Prophylactic cranial irradiation (PCI) as a non-specific treatment has proven to be a powerful tool in preventing BM without affecting overall survival in neither way. That has been proved in nearly all earlier and all recent studies—NVALT11/DLCRG-02, RTOG 0214 update, Li et al. The positive effect of BM incidence reduction may draw fear form PCI usage due to potential cognitive toxicity the PCI may cause. Results of recent trials show that after PCI only mild cognitive disorders (MCD) may arise. Promising results in terms of reducing MCD are shown when memantine is used or/and hippocampal avoidance techniques are implemented. HA in PCI seem to be cost effective but calculations were made on small-cell lung cancer cohorts. Still even recent studies did not clarify finally which patients could benefit from PCI or other forms of preventing BM. It seems that new trials should focus on younger, fit and non-squamous histology patients and use the tests for mild cognitive disorders (MoCA, BHA) rather than screening tests for dementia (MMSE, HVLT, ADL). The main obstacle in performing new trials on PCI in NSCLC cohorts may be, however, patients’ accrual, as a difficulty which occurred during latest trials.

Temozolomide: An Updated Overview of Resistance Mechanisms, Nanotechnology Advances and Clinical Applications

Temozolomide (TMZ), an oral alkylating prodrug which delivers a methyl group to purine bases of DNA (O6-guanine; N7-guanine and N3-adenine), is frequently used together with radiotherapy as part of the first-line treatment of high-grade gliomas. The main advantages are its high oral bioavailability (almost 100% although the concentration found in the cerebrospinal fluid was approximately 20% of the plasma concentration of TMZ), its lipophilic properties, and small size that confer the ability to cross the blood-brain barrier. Furthermore, this agent has demonstrated activity not only in brain tumors but also in a variety of solid tumors. However, conventional therapy using surgery, radiation, and TMZ in glioblastoma results in a median patient survival of 14.6 months. Treatment failure has been associated with tumor drug resistance. This phenomenon has been linked to the expression of O6-methylguanine-DNA methyltransferase, but the mismatch repair system and the presence of cancer stem-like cells in tumors have also been related to TMZ resistance. The understanding of these mechanisms is essential for the development of new therapeutic strategies in the clinical use of TMZ, including the use of nanomaterial delivery systems and the association with other chemotherapy agents. The aim of this review is to summarize the resistance mechanisms of TMZ and the current advances to improve its clinical use.

Strategies to prevent brain metastasis

PURPOSE OF REVIEW

The current article reviews the state of art of prevention strategies for brain metastases from solid tumors and touches both old pivotal studies and new directions of personalized molecular approaches.

RECENT FINDINGS

Prophylactic cranial irradiation (PCI) has a definite role in the prevention of relapse into the brain for patients with small cell lung cancer (SCLC) responding to chemotherapy and radiotherapy as it prolongs overall survival (OS). However, the risk of late cognitive deficit following whole brain radiotherapy (WBRT) in this patient population is still not well known. Conversely, PCI significantly reduces the incidence of brain metastases and prolongs the disease-free interval in patients with non-SCLC (NSCLC), but does not improve OS thus far. Pharmacologic prevention is a new concept driven by the efficacy of targeted agents on macrometastases from specific molecular subgroups.

SUMMARY

The future challenges for prevention of brain metastases are represented by the identification of subgroups of patients at higher risk of relapse into the brain coupled with either new WBRT strategies to better preserve cognition or effective molecular agents to target micrometastases.

Brain metastases

An estimated 20% of all patients with cancer will develop brain metastases, with the majority of brain metastases occurring in those with lung, breast and colorectal cancers, melanoma or renal cell carcinoma. Brain metastases are thought to occur via seeding of circulating tumour cells into the brain microvasculature; within this unique microenvironment, tumour growth is promoted and the penetration of systemic medical therapies is limited. Development of brain metastases remains a substantial contributor to overall cancer mortality in patients with advanced-stage cancer because prognosis remains poor despite multimodal treatments and advances in systemic therapies, which include a combination of surgery, radiotherapy, chemotherapy, immunotherapy and targeted therapies. Thus, interest abounds in understanding the mechanisms that drive brain metastases so that they can be targeted with preventive therapeutic strategies and in understanding the molecular characteristics of brain metastases relative to the primary tumour so that they can inform targeted therapy selection. Increased molecular understanding of the disease will also drive continued development of novel immunotherapies and targeted therapies that have higher bioavailability beyond the blood-tumour barrier and drive advances in radiotherapies and minimally invasive surgical techniques. As these discoveries and innovations move from the realm of basic science to preclinical and clinical applications, future outcomes for patients with brain metastases are almost certain to improve.

Clinical trial design for systemic agents in patients with brain metastases from solid tumours: a guideline by the Response Assessment in Neuro-Oncology Brain Metastases working group

Patients with active CNS disease are often excluded from clinical trials, and data regarding the CNS efficacy of systemic agents are usually obtained late in the drug development process or not at all. In this guideline from the Response Assessment in Neuro-Oncology Brain Metastases (RANO-BM) working group, we provide detailed recommendations on when patients with brain metastases from solid tumours should be included or excluded in clinical trials of systemic agents. We also discuss the limitations of retrospective studies in determining the CNS efficacy of systemic drugs. Inclusion of patients with brain metastases early on in the clinical development of a drug or a regimen is needed to generate appropriate CNS efficacy or non-efficacy signals. We consider how to optimally incorporate or exclude such patients in systemic therapy trials depending on the likelihood of CNS activity of the agent by considering three scenarios: drugs that are considered very unlikely to have CNS antitumour activity or efficacy; drugs that are considered very likely to have CNS activity or efficacy; and drugs with minimal baseline information on CNS activity or efficacy. We also address trial design issues unique to patients with brain metastases, including the selection of appropriate CNS endpoints in systemic therapy trials.

Constitutional mismatch repair-deficiency: current problems and emerging therapeutic strategies

Mismatch repair (MMR) proteins remove errors from newly synthesized DNA, improving the fidelity of DNA replication. A loss of MMR causes a mutated phenotype leading to a predisposition to cancer. In the last 20 years, an increasing number of patients have been described with biallelic MMR gene mutations in which MMR defects are inherited from both parents. This leads to a syndrome with recessive inheritance, referred to as constitutional mismatch repair-deficiency (CMMRD). CMMRD is a rare childhood cancer predisposition syndrome. The spectrum of CMMRD tumours is broad and CMMRD-patients possess a high risk of multiple cancers including hematological, brain and intestinal tumors. The severity of CMMRD is highlighted by the fact that patients do not survive until later life, emphasising the requirement for new therapeutic interventions. Many tumors in CMMRD-patients are hypermutated leading to the production of truncated protein products termed neoantigens. Neoantigens are recognized as foreign by the immune system and induce antitumor immune responses. There is growing evidence to support the clinical efficacy of neoantigen based vaccines and immune checkpoint inhibitors (collectively referred to as immunotherapy) for the treatment of CMMRD cancers. In this review, we discuss the current knowledge of CMMRD, the advances in its diagnosis, and the emerging therapeutic strategies for CMMRD-cancers.

Brain metastases in ALK-positive NSCLC - time to adjust current treatment algorithms

The progress in molecular biology has revolutionized systemic treatment of advanced non-small-cell lung cancer (NSCLC) from conventional chemotherapy to a treatment stratified by histology and genetic aberrations. Tumors harboring a translocation of the anaplastic-lymphoma-kinase (ALK) gene constitute a distinct genetic and clinico-pathologic NSCLC subtype with patients with ALK-positive disease being at a higher risk for developing brain metastases. Due to the introduction of effective targeted therapy with ALK-inhibitors, today, patients with advanced ALK-positive NSCLC achieve high overall response rates and remain progression-free for long time intervals. Moreover, ALK-inhibitors seem to exhibit efficacy in the treatment of brain metastases. In the light of this, it needs to be discussed how treatment algorithms for managing patients with brain metastases should be modified. By integrating systemic ALK-inhibitor therapy, radiotherapy, in particular whole brain radiotherapy might be postponed deferring potential long-term impairment by neurocognitive deficits to a later time point in the course of the disease. An early treatment of asymptomatic brain metastases might offer patients a longer time without impairment of cerebral symptoms or radiotherapeutic interventions. Based on an updated extensive review of the literature this article provides an overview on the epidemiology and the treatment of patients’ brain metastases. It describes the specifics of ALK-positive disease and proposes an algorithm for the treatment of patients with advanced ALK-positive NSCLC and brain metastases.

Preventing central nervous system metastases in non-small cell lung cancer

INTRODUCTION

There are no effective central nervous system (CNS) metastases prevention methods in lung cancer patients. Prophylactic cranial irradiation has a limited effectiveness and relatively high toxicity. Systemic chemotherapy is not relevant in reducing the risk of CNS in lung cancer patients. The understanding of molecular background of brain metastases in non-small cell lung cancer (NSCLC) patients could contribute to the development of personalized treatments for such patients. Areas covered: This article summarizes the latest clinical trials concerning the use of radiotherapy, chemotherapy, molecularly targeted therapies, and immunotherapy in lung cancer patients, with particular consideration of brain lung cancer metastasis prevention. The literature search was undertaken via PubMed and EMBASE searches and relevant articles are included in this review. Expert commentary: The recent data supports that EGFR-TKIs and ALK inhibitors are clinically relevant for first-line treatment to prevent and treat CNS metastases in molecularly selected NSCLC patients. In the future, high hopes for the prevention of CNS metastases in NSCLC patients are associated with immunotherapy concerning immune check-points inhibitors.

Stereotactic Radiosurgery for Treatment of Brain Metastases

Brain metastases are the most common intracranial malignancy. Incidence of brain metastases has risen as systemic therapies have improved and patients with metastatic disease live longer. Whole-brain radiation therapy, for many years, has been the standard treatment approach. Stereotactic radiosurgery has become an increasingly popular option because of its relatively short, convenient, and noninvasive treatment course. Although recently published data have renewed interest in use of whole-brain radiation therapy or systemic therapies for control of micrometastatic disease, stereotactic radiosurgery continues to be an important modality, capable of delivering ablative doses of radiation for long-term control of macroscopic disease. The purpose of this review is to explore the different paradigms for incorporation of stereotactic radiosurgery into management of brain metastases. Current uses for stereotactic radiosurgery include delivery as a boost with whole-brain radiation therapy; alone for patients with a limited number of brain metastases; in pre- or postoperative settings; and in combination with systemic, targeted, and immune-based therapies. Mature prospective data on use of stereotactic radiosurgery in combination with whole-brain radiation therapy is available; however, prospective, randomized data on stereotactic radiosurgery for patients with a greater number of brain metastases, its use in pre- and postoperative settings, and its use in combination with systemic therapies are limited. Data from ongoing and future studies are needed to define the appropriate use of stereotactic radiosurgery in these settings.

Baseline neutrophil-lymphocyte ratio is associated with baseline and subsequent presence of brain metastases in advanced non-small-cell lung cancer

We examined the predictive value of neutrophil–lymphocyte ratio (NLR) by examining their association with the baseline presence and subsequent development of brain metastases in patients with stage IV non-small cell lung cancer (NSCLC). We examined the predictive value of NLR for brain metastasis in 260 stage IV NSCLC. Logistic regression models and competing risk analysis were used to determine the association of NLR with baseline and subsequent presence of brain metastases. Multivariate analysis reveals that patients with high NLR (≥4.95) had significantly more brain metastases at diagnosis than those with low NLR (Odds Ratio = 2.59, P = 0.01). In patients who had no baseline brain metastasis, competing risks analysis revealed that patients with high NLR showed higher cumulative incidence of subsequent brain metastases, compared to those with low NLR (P = 0.017). A high NLR was associated with the baseline presence or the subsequent development of brain metastases, particularly in the group with adenocarcinoma (P = 0.013 and P = 0.044, respectively). Furthermore, an increase in NLR during treatment was associated with subsequent brain metastases (P = 0.004). The NLR is an independent predictive factor for the baseline presence of brain metastases and subsequent brain metastases in stage IV NSCLC.

Updates in the management of brain metastases

The clinical management/understanding of brain metastases (BM) has changed substantially in the last 5 years, with key advances and clinical trials highlighted in this review. Several of these changes stem from improvements in systemic therapy, which have led to better systemic control and longer overall patient survival, associated with increased time at risk for developing BM. Development of systemic therapies capable of preventing BM and controlling both intracranial and extracranial disease once BM are diagnosed is paramount. The increase in use of stereotactic radiosurgery alone for many patients with multiple BM is an outgrowth of the desire to employ treatments focused on local control while minimizing cognitive effects associated with whole brain radiotherapy. Complications from BM and their treatment must be considered in comprehensive patient management, especially with greater awareness that the majority of patients do not die from their BM. Being aware of significant heterogeneity in prognosis and therapeutic options for patients with BM is crucial for appropriate management, with greater attention to developing individual patient treatment plans based on predicted outcomes; in this context, recent prognostic models of survival have been extensively revised to incorporate molecular markers unique to different primary cancers.

The Architecture and Function of Monoclonal Antibody-Functionalized Mesoporous Silica Nanoparticles Loaded with Mifepristone: Repurposing Abortifacient for Cancer Metastatic Chemoprevention

The circulating tumor cells (CTCs) existing in cancer survivors are considered the root cause of cancer metastasis. To prevent the devastating metastasis cascade from initiation, we hypothesize that a biodegradable nanomaterial loaded with the abortifacient mifepristone (MIF) and conjugated with the epithelial cell adhesion molecule antibody (aEpCAM) may serve as a safe and effective cancer metastatic preventive agent by targeting CTCs and preventing their adhesion-invasion to vascular intima. It is demonstrated that MIF-loaded mesoporous silica nanoparticles (MSN) coated with aEpCAM (aE-MSN-M) can specifically target and bind colorectal cancer cells in either cell medium or blood through EpCAM recognition proven by quantitative flow cytometric detection and free aEpCAM competitive assay. The specific binding results in downregulation of the captured cells and drives them into G0/G1 phase primarily attributed to the effect of aEpCAM. The functional nanoparticles significantly inhibit the heteroadhesion between cancer cells and endothelial cells, suggesting the combined inhibition effects of aEpCAM and MIF on E-selectin and ICAM-1 expression. The functionalized nanoparticles circulate in mouse blood long enough to deliver MIF and inhibit lung metastasis. The present proof-of-concept study shows that the aE-MSN-M can prevent cancer metastasis by restraining CTC activity and their adhesion-invasion to vascular intima.