Managing leptomeningeal melanoma metastases in the era of immune and targeted therapy

Survival and treatment outcomes in patients with leptomeningeal disease from metastatic melanoma

Background

Melanoma leptomeningeal disease (LMD) has a poor prognosis. However, the management of patients with advanced melanoma has evolved with time, including those with LMD. We reviewed a large cohort of melanoma LMD patients to assess factors associated with survival.

Methods

Retrospective clinical data was collected on patients diagnosed with LMD at MD Anderson Cancer Center from 2015 to 2020. Overall survival (OS) was determined from LMD diagnosis to date of death or last follow-up. The Kaplan-Meier method and log-rank test were used to estimate OS and to assess univariate group differences, respectively. Multivariable associations of survival with variables of interest were determined using Cox proportional hazards regression models.

Results

A total of 172 patients were identified. The median age at LMD diagnosis was 53 (range 20-79) years, and all patients had radiographic evidence of LMD on magnetic resonance imaging of either brain or spine. In total 143 patients previously received systemic therapy (83%), with a median of 2 prior treatments (range 0-5). 81 patients (47%) had concurrent uncontrolled systemic disease and 80 patients (53%) had elevated serum LDH at the time of diagnosis. With a median follow-up of 4.0 months (range 0.1-65.3 months), median OS for all patients from LMD diagnosis was 4.9 months. Patients (n = 45) who received intrathecal therapy or systemic immunotherapy for LMD had a median OS of 8.0 months and 10.2 months, respectively. On multivariable analysis, decreased performance status, positive CSF cytology, elevated LDH, and whole brain radiation were associated with worse OS.

Conclusions

Despite many advances in therapeutic options, the outcomes of melanoma patients with LMD remains poor. However, a subset of patients appears to derive benefit from LMD-directed treatment.

Spatial transcriptomics analysis identifies a tumor-promoting function of the meningeal stroma in melanoma leptomeningeal disease

Leptomeningeal disease (LMD) remains a rapidly lethal complication for late-stage melanoma patients. Here, we characterize the tumor microenvironment of LMD and patient-matched extra-cranial metastases using spatial transcriptomics in a small number of clinical specimens (nine tissues from two patients) with extensive in vitro and in vivo validation. The spatial landscape of melanoma LMD is characterized by a lack of immune infiltration and instead exhibits a higher level of stromal involvement. The tumor-stroma interactions at the leptomeninges activate tumor-promoting signaling, mediated through upregulation of SERPINA3. The meningeal stroma is required for melanoma cells to survive in the cerebrospinal fluid (CSF) and promotes MAPK inhibitor resistance. Knocking down SERPINA3 or inhibiting the downstream IGR1R/PI3K/AKT axis results in tumor cell death and re-sensitization to MAPK-targeting therapy. Our data provide a spatial atlas of melanoma LMD, identify the tumor-promoting role of meningeal stroma, and demonstrate a mechanism for overcoming microenvironment-mediated drug resistance in LMD.

Enrollment Trends Among Patients with Melanoma Brain Metastasis in Active Clinical Trials

The CNS is a common site for distant metastasis and treatment failure in melanoma patients. This study aimed to evaluate the inclusion rate of patients with melanoma brain metastases (MBM) in prospective clinical trials. 69.3% of trials excluded MBM patients based on their CNS disease. In univariate analysis, trials not employing immunotherapy (p = 0.0174), inclusion of leptomeningeal disease (p < 0.0001) and non-pharmaceutical sponsor trials (p = 0.0461) were more likely to enroll patients with MBM. Thoughtful reconsideration of clinical trial designs is needed to give patients with MBMs access to promising investigational agents and improve outcomes for patients with MBM.

Integration analysis of single-cell transcriptome reveals specific monocyte subsets associated with melanoma brain and leptomeningeal metastasis

BACKGROUND

Melanoma central nervous system (CNS) metastasis remains a leading cause of patient mortality, and the underlying pathological mechanism has not been fully elucidated, leading to a lack of effective therapeutic strategies.

MATERIALS AND METHODS

In this study, we conducted an integrated analysis of single-cell transcriptomic data related to melanoma brain metastasis (MBM) and leptomeningeal metastasis (LMM). We focused on differences of subset composition and molecular expression of monocytes in blood, primary tumor, brain metastases, and leptomeningeal metastases.

RESULTS

Significant differences were observed among monocytes in blood, primary tumor, and different CNS metastatic tissues, particularly in terms of subset differentiation and gene expression patterns. Subsequent analysis revealed the upregulation of cell proportions of six monocyte subsets in brain metastasis and leptomeningeal metastasis. Based on differential gene analysis, four of these subsets exhibited increased expression of factors promoting tumor migration and survival, including AREG+ monocytes (AREG, EREG, THBS1), FABP5+ monocytes (SPP1, CCL2, CTSL), and CXCL3+ monocytes (CXCL3, IL8, IL1B). The proportions of TPSB2+ monocytes (IL32, CCL5) were notably elevated in melanoma leptomeningeal metastasis tissues. Pathway analysis indicated the activation of signaling pathways such as NOD-like receptors, NFκB, and Toll-like receptors in these metastasis-related subsets.

CONCLUSION

Our findings elucidate that AREG+, FABP5+ and CXCL3+ monocytes are associated with brain metastasis and TPSB2+ monocytes are associated with leptomeningeal metastasis in melanoma, which may be contribute to the development of therapeutic strategies focusing on monocytes or cytokines for melanoma CNS metastasis.

Leptomeningeal disease in melanoma: An update on the developments in pathophysiology and clinical care

Leptomeningeal disease (LMD) remains a major challenge in the clinical management of metastatic melanoma patients. Outcomes for patient remain poor, and patients with LMD continue to be excluded from almost all clinical trials. However, recent trials have demonstrated the feasibility of conducting prospective clinical trials in these patients. Further, new insights into the pathophysiology of LMD are identifying rational new therapeutic strategies. Here we present recent advances in the understanding of, and treatment options for, LMD from metastatic melanoma. We also annotate key areas of future focus to accelerate progress for this challenging but emerging field.

Spatial transcriptomics analysis identifies a unique tumor-promoting function of the meningeal stroma in melanoma leptomeningeal disease

Leptomeningeal disease (LMD) remains a rapidly lethal complication for late-stage melanoma patients. The inaccessible nature of the disease site and lack of understanding of the biology of this unique metastatic site are major barriers to developing efficacious therapies for patients with melanoma LMD. Here, we characterize the tumor microenvironment of the leptomeningeal tissues and patient-matched extra-cranial metastatic sites using spatial transcriptomic analyses with in vitro and in vivo validation. We show the spatial landscape of melanoma LMD to be characterized by a lack of immune infiltration and instead exhibit a higher level of stromal involvement. We show that the tumor-stroma interactions at the leptomeninges activate pathways implicated in tumor-promoting signaling, mediated through upregulation of SERPINA3 at the tumor-stroma interface. Our functional experiments establish that the meningeal stroma is required for melanoma cells to survive in the CSF environment and that these interactions lead to a lack of MAPK inhibitor sensitivity in the tumor. We show that knocking down SERPINA3 or inhibiting the downstream IGR1R/PI3K/AKT axis results in re-sensitization of the tumor to MAPK-targeting therapy and tumor cell death in the leptomeningeal environment. Our data provides a spatial atlas of melanoma LMD, identifies the tumor-promoting role of meningeal stroma, and demonstrates a mechanism for overcoming microenvironment-mediated drug resistance unique to this metastatic site.

Novel approaches to treatment of leptomeningeal metastases

PURPOSE OF REVIEW

The incidence of leptomeningeal metastases is increasing in the setting of improved survival from systemic cancers. In more recent years, our understanding of leptomeningeal metastasis pathogenesis, how to diagnose and treat has been evolving.

RECENT FINDINGS

Diagnosing leptomeningeal metastasis has been challenging due to the limitations of cytology and neuroimaging; However, newer techniques detecting circulating tumor cells (CTCs) or circulating tumor DNA (ctDNA) have shown potential advantage with diagnosis, quantification and detection of oncogenic mutations. The use of small molecule inhibitors and immunotherapy has shown some promise in specific leptomeningeal metastasis subtypes.

SUMMARY

These new discoveries have improved clinical trials' ability to assess treatment response and thereby more optimally compare different treatments. Furthermore, they have helped the individual clinician better diagnose, monitor the disease and provide novel therapies.

Leptomeningeal Metastasis: A Review of the Pathophysiology, Diagnostic Methodology, and Therapeutic Landscape

The present review aimed to establish an understanding of the pathophysiology of leptomeningeal disease as it relates to late-stage development among different cancer types. For our purposes, the focused metastatic malignancies include breast cancer, lung cancer, melanoma, primary central nervous system tumors, and hematologic cancers (lymphoma, leukemia, and multiple myeloma). Of note, our discussion was limited to cancer-specific leptomeningeal metastases secondary to the aforementioned primary cancers. LMD mechanisms secondary to non-cancerous pathologies, such as infection or inflammation of the leptomeningeal layer, were excluded from our scope of review. Furthermore, we intended to characterize general leptomeningeal disease, including the specific anatomical infiltration process/area, CSF dissemination, manifesting clinical symptoms in patients afflicted with the disease, detection mechanisms, imaging modalities, and treatment therapies (both preclinical and clinical). Of these parameters, leptomeningeal disease across different primary cancers shares several features. Pathophysiology regarding the development of CNS involvement within the mentioned cancer subtypes is similar in nature and progression of disease. Consequently, detection of leptomeningeal disease, regardless of cancer type, employs several of the same techniques. Cerebrospinal fluid analysis in combination with varied imaging (CT, MRI, and PET-CT) has been noted in the current literature as the gold standard in the diagnosis of leptomeningeal metastasis. Treatment options for the disease are both varied and currently in development, given the rarity of these cases. Our review details the differences in leptomeningeal disease as they pertain through the lens of several different cancer subtypes in an effort to highlight the current state of targeted therapy, the potential shortcomings in treatment, and the direction of preclinical and clinical treatments in the future. As there is a lack of comprehensive reviews that seek to characterize leptomeningeal metastasis from various solid and hematologic cancers altogether, the authors intended to highlight not only the overlapping mechanisms but also the distinct patterning of disease detection and progression as a means to uniquely treat each metastasis type. The scarcity of LMD cases poses a barrier to more robust evaluations of this pathology. However, as treatments for primary cancers have improved over time, so has the incidence of LMD. The increase in diagnosed cases only represents a small fraction of LMD-afflicted patients. More often than not, LMD is determined upon autopsy. The motivation behind this review stems from the increased capacity to study LMD in spite of scarcity or poor patient prognosis. In vitro analysis of leptomeningeal cancer cells has allowed researchers to approach this disease at the level of cancer subtypes and markers. We ultimately hope to facilitate the clinical translation of LMD research through our discourse.

Gene-edited and -engineered stem cell platform drives immunotherapy for brain metastatic melanomas

Oncolytic virus therapy has shown activity against primary melanomas; however, its efficacy in brain metastases remains challenging, mainly because of the delivery and immunosuppressive nature of tumors in the brain. To address this challenge, we first established PTEN-deficient melanoma brain metastasis mouse models and characterized them to be more immunosuppressive compared with primary melanoma, mimicking the clinical settings. Next, we developed an allogeneic twin stem cell (TSC) system composed of two tumor-targeting stem cell (SC) populations. One SC was loaded with oncolytic herpes simplex virus (oHSV), and the other SC was CRISPR-Cas9 gene-edited to knock out nectin 1 (N1) receptor (N1KO) to acquire resistance to oHSV and release immunomodulators, such as granulocyte-macrophage colony-stimulating factor (GM-CSF). Using mouse models of brain metastatic BRAFV600E/PTEN-/- and BRAFV600E/wt/PTEN-/- mutant melanomas, we show that locoregional delivery of TSCs releasing oHSV and GM-CSF (TSC-G) activated dendritic cell- and T cell-mediated immune responses. In addition, our strategy exhibited greater therapeutic efficacy when compared with the existing oncolytic viral therapeutic approaches. Moreover, the TSCs composed of SC-oHSV and SCN1KO-releasing GM-CSF and single-chain variable fragment anti-PD-1 (TSC-G/P) had therapeutic efficacy in both syngeneic and patient-derived humanized mouse models of leptomeningeal metastasis. Our findings provide a promising allogeneic SC-based immunotherapeutic strategy against melanomas in the CNS and a road map toward clinical translation.

Leptomeningeal Disease (LMD) in Patients with Melanoma Metastases

Leptomeningeal disease (LMD) is a devastating complication caused by seeding malignant cells to the cerebrospinal fluid (CSF) and the leptomeningeal membrane. LMD is diagnosed in 5-15% of patients with systemic malignancy. Management of LMD is challenging due to the biological and metabolic tumor microenvironment of LMD being largely unknown. Patients with LMD can present with a wide variety of signs and/or symptoms that could be multifocal and include headache, nausea, vomiting, diplopia, and weakness, among others. The median survival time for patients with LMD is measured in weeks and up to 3-6 months with aggressive management, and death usually occurs due to progressive neurologic dysfunction. In melanoma, LMD is associated with a suppressive immune microenvironment characterized by a high number of apoptotic and exhausted CD4⁺ T-cells, myeloid-derived suppressor cells, and a low number of CD8⁺ T-cells. Proteomics analysis revealed enrichment of complement cascade, which may disrupt the blood-CSF barrier. Clinical management of melanoma LMD consists primarily of radiation therapy, BRAF/MEK inhibitors as targeted therapy, and immunotherapy with anti-PD-1, anti-CTLA-4, and anti-LAG-3 immune checkpoint inhibitors. This review summarizes the biology and anatomic features of melanoma LMD, as well as the current therapeutic approaches.

An open label, non-randomised, phase IIIb study of trametinib in combination with dabrafenib in patients with unresectable (stage III) or distant metastatic (stage IV) BRAF V600-mutant melanoma: A subgroup analysis of patients with brain metastases

BACKGROUND

Despite the poor prognosis associated with melanoma brain metastases (BM), data concerning these patients and their inclusion in clinical trials remains scarce. We report here the efficacy results of a subgroup analysis in patients with BRAFV600-mutant melanoma and BM treated with BRAF and MEK inhibitors dabrafenib (D) and trametinib (T).

PATIENTS AND METHODS

This phase IIIb single-arm, open-label, multicenter, French study included patients with unresectable stage IIIc or IV BRAFV600-mutant melanoma with or without BM. The present analysis focuses on patients with BM. Response rates were determined clinically and/or radiologically as per standard clinical practice. Progression-free survival (PFS) was estimated using the Kaplan Meier analysis and modelled with multivariate Cox regression model. Risk subgroups were identified using an exponential regression tree analysis. Significance was set at p < 0.05.

RESULTS

Between March 2015 and November 2016, 856 patients were included and 275 (32%) patients had BM. Median PFS was 5.68 months (95% confidence interval [CI], 5.29-6.87). Significant independent factors associated with shorter PFS were ECOG ≥1, elevated serum lactate dehydrogenase (LDH), ≥3 metastatic sites, and non-naïve status. The binary-split classification and regression tree modelling identified baseline LDH and ECOG status as major prognostic factors.

CONCLUSION

This is to date the largest, close to real-world, study in advanced BRAFV600-mutant melanoma patients with BM treated with D+T. ECOG >1, ≥3 metastatic sites and elevated LDH were associated with shorter PFS, a finding previously demonstrated only in patients without BM. Further studies are warranted to determine the optimal treatment sequence in this population.

Leptomeningeal dissemination as a first sign of progression in metastatic melanoma: a diagnostic lesson

One of the most serious complications of advanced melanoma is the diffusion of cancer cells to the central nervous system. The diagnosis of leptomeningeal metastasis (LMM) is notoriously challenging and requires a combination of consistent MRI and cerebrospinal fluid (CSF) cytology. In ambiguous cases, mutations like BRAF V600E in CSF-cell-free (cf)DNA may help to clarify diagnosis of LMM. Here we present the case of a young woman who developed isolated LMM after the diagnosis of a node-positive primary melanoma with normal LDH. The CSF was negative for tumour cells by cytology but positive for cfDNA BRAF V600E mutation, thus allowing us to diagnose LMM. To our knowledge, this is the first case where CSF sampling for the detection of BRAF mutation was used to identify leptomeningeal disease in the presence of negative MRI and without involvement of any other distant sites.

Surgical and anatomic factors predict development of leptomeningeal disease in patients with melanoma brain metastases

BACKGROUND

Leptomeningeal disease (LMD) is a devastating complication of systemic malignancy, of which there is an unclear etiology. The aim of this study is to determine if surgical or anatomic factors can predict LMD in patients with metastatic melanoma.

METHODS

A retrospective chart review was performed of 1162 patients treated at single institution for melanoma brain metastases (MBM). Patients with fewer than 3 months follow-up or lacking appropriate imaging were excluded. Demographic information, surgical, and anatomic data were collected.

RESULTS

Eight hundred and twenty-seven patients were included in the final review. On multivariate analysis for the entire cohort, female gender, dural-based and intraventricular metastasis, and tumor bordering CSF spaces were associated with increased risk of LMD. Surgical resection was not significant for risk of LMD. On multivariate analysis of patients who have undergone surgical resection of a metastatic tumor, dural-based and intraventricular metastasis, ventricular entry during surgery, and metastasis in the infratentorial space were associated with increased risk of LMD. On multivariate analysis of patients who did not undergo surgery, chemotherapy after initial diagnosis and metastasis bordering CSF spaces were associated with increased risk of LMD.

CONCLUSION

In a single-institution cohort of MBM, we found that surgical resection alone did not result in an increased risk of LMD. Anatomical factors such as dural-based and intraventricular metastasis were significant for developing LMD, as well as entry into a CSF space during surgical resection. These data suggest a strong correlation between anatomic location and tumor cell seeding in relation to the development of LMD.

Leptomeningeal metastasis from melanoma emulating chronic subdural hematoma: a case report

Background

Melanoma is a disease in which the patient doesn’t know about the primary lesion, and it has a propensity to metastases to any organ in the human body. Amongst melanoma, leptomeningeal metastasis has the least incidence.

Case presentation

In this case, we report a 56-year-old lady presenting with headache, recurrent vomiting and slurring of speech which on imaging was suggestive of chronic subdural hematoma which had led to surgical preparation but upon further examination, and radioimaging was found to be leptomeningeal metastasis from melanoma for which systemic therapy was started.

Conclusions

The concern is vigilance that is much needed in any case presenting in emergency. When the diagnosis is chronic subdural hematoma, it is followed by surgical treatment which is not done for leptomeningeal metastasis.

Novel human melanoma brain metastasis models in athymic nude fox1nu mice: Site-specific metastasis patterns reflecting their clinical origin

BACKGROUND

Malignant melanomas frequently metastasize to the brain, but metastases in the cerebellum are underrepresented compared with metastases in the cerebrum.

METHODS

We established animal models by injecting intracardially in athymic nude fox1nu mice two human melanoma cell lines, originating from a cerebral metastasis (HM19) and a cerebellar metastasis (HM86).

RESULTS

Using magnetic resonance imaging (MRI), metastases were first detected after a mean of 34.5 days. Mean survival time was 59.6 days for the mice in the HM86 group and significantly shorter (43.7 days) for HM19-injected animals (p < 0.001). In the HM86 group, the first detectable metastasis was located in the cerebellum in 15/55 (29%) mice compared with none in the HM19 group (p < 0.001). At sacrifice, cerebellar metastases were found in 34/55 (63%) HM86-injected mice compared with 1/53 (2%) in the HM19-injected (p < 0.001) mice. At that time, all mice in both groups had detectable metastases in the cerebrum. Comparing macroscopic and histologic appearances of the brain metastases with their clinical counterparts, the cell line-based tumors had kept their original morphologic characteristics.

CONCLUSIONS

The present work demonstrates that human brain-metastatic melanoma cells injected intracardially in mice had retained inherent characteristics also in reproducing interaction with subtle microenvironmental brain tissue compartment-specific features. The models offer new possibilities for investigating tumor- and host-associated factors involved in determining tissue specificity of brain metastasis.

Advances in the diagnosis, evaluation, and management of leptomeningeal disease

Leptomeningeal metastasis (LM) is a devastating complication of cancer with variable clinical presentation and limited benefit from existing treatment options. In this review, we discuss advances in LM diagnostics and therapeutics with the potential to reverse this grim course. Emerging cerebrospinal fluid circulating tumor cell and cell-free tumor DNA analysis technologies will improve diagnosis of LM, while providing crucial genetic information, capturing tumor heterogeneity, and quantifying disease burden. Circulating tumor cells and cell-free tumor DNA have utility as biomarkers to track disease progression and treatment response. Treatment options for LM include ventriculoperitoneal shunting for symptomatic relief, radiation therapy including whole-brain radiation and focal radiation for bulky leptomeningeal involvement, and systemic and intrathecal medical therapies, including targeted and immunotherapies based on tumor mutational profiling. While existing treatments for LM have limited efficacy, recent advances in liquid biopsy together with increasing availability of targeted treatments will lead to rational multimodal individualized treatments and improved patient outcomes.

Neoplastic meningitis in solid tumours: updated review of diagnosis, prognosis, therapeutic management, and future directions

Neoplastic meningitis (NM) is a relatively frequent metastatic complication of cancer associated with high levels of neurological morbidity and generally poor prognosis. It appears in 5%-15% of patients with solid tumours, the most frequent being breast and lung cancer and melanoma. Symptoms are caused by involvement of the cerebral hemispheres, cranial nerves, spinal cord, and nerve roots, and are often multifocal or present with signs and symptoms of intracranial hypertension. The main diagnostic tools are the neurological examination, brain and spinal cord contrast-enhanced magnetic resonance imaging, and cerebrospinal fluid analysis including cytology, although studies have recently been conducted into the detection of tumour cells and DNA in the cerebrospinal fluid, which increases diagnostic sensitivity. With the currently available therapies, treatment aims not to cure the disease, but to delay and ameliorate the symptoms and to preserve quality of life. Treatment of NM involves a multimodal approach that may include radiotherapy, intrathecal and/or systemic chemotherapy, and surgery. Treatment should be individualised, and is based mainly on clinical practice guidelines and expert opinion. Promising clinical trials are currently being conducted to evaluate drugs with molecular and immunotherapeutic targets. This article is an updated review of NM epidemiology, clinical presentation, diagnosis, prognosis, management, and treatment; it is aimed at general neurologists and particularly at neurologists practicing in hospital settings with oncological patients.

CD11c+CD163+ Cells and Signal Transducer and Activator of Transcription 3 (STAT3) Expression Are Common in Melanoma Leptomeningeal Disease

Leptomeningeal disease (LMD) in melanoma patients is associated with significant neurological sequela and has a dismal outcome, with survival measured typically in weeks. Despite the therapeutic benefit of targeted therapies and immunotherapies for Stage IV melanoma, patients with LMD do not typically benefit. A deeper understanding of the tumor microenvironment (TME) of LMD may provide more appropriate therapeutic selection. A retrospective analysis of subjects who underwent surgical resection with LMD (n=8) were profiled with seven color multiplex staining to evaluate the expression of the global immune suppressive hub - the signal transducer and activator of transcription 3 (STAT3) and for the presence of CD3+ T cells, CD68+ monocyte-derived cells, CD163+ immune suppressive macrophages, and CD11c+ cells [potential dendritic cells (DCs)] in association with the melanoma tumor marker S100B and DAPI for cellular nuclear identification. High-resolution cellular imaging and quantification was conducted using the Akoya Vectra Polaris. CD11c+ cells predominate in the TME (10% of total cells), along with immunosuppressive macrophages (2%). Another potential subset of DCs co-expressing CD11c+ and the CD163+ immunosuppressive marker is frequently present (8/8 of specimens, 8%). Occasional CD3+ T cells are identified, especially in the stroma of the tumor (p=0.039). pSTAT3 nuclear expression is heterogeneous in the various immune cell populations. Occasional immune cluster interactions can be seen in the stroma and on the edge. In conclusion, the TME of LMD is largely devoid of CD3+ T cells but is enriched in immune suppression and innate immunity.

The Liquid Biopsy for Lung Cancer: State of the Art, Limitations and Future Developments

Simple Summary

During the development and progression of lung tumors, processes such as necrosis and vascular invasion shed tumor cells or cellular components into various fluid compartments. Liquid biopsies consist of obtaining a bodily fluid, typically peripheral blood, in order to isolate and investigate these shed tumor constituents. Circulating tumor cells (CTCs) are one such constituent, which can be isolated from blood and can act as a diagnostic aid and provide valuable prognostic information. Liquid-based biopsies may also have a potential future role in lung cancer screening. Circulating tumor DNA (ctDNA) is found in small quantities in blood and, with the recent development of sensitive molecular and sequencing technologies, can be used to directly detect actionable genetic alterations or monitor for resistance mutations and guide clinical management. While potential benefits of liquid biopsies are promising, they are not without limitations. In this review, we summarize the current state and limitations of CTCs and ctDNA and possible future directions.

Abstract

Lung cancer is a leading cause of cancer-related deaths, contributing to 18.4% of cancer deaths globally. Treatment of non-small cell lung carcinoma has seen rapid progression with targeted therapies tailored to specific genetic drivers. However, identifying genetic alterations can be difficult due to lack of tissue, inaccessible tumors and the risk of complications for the patient with serial tissue sampling. The liquid biopsy provides a minimally invasive method which can obtain circulating biomarkers shed from the tumor and could be a safer alternative to tissue biopsy. While tissue biopsy remains the gold standard, liquid biopsies could be very beneficial where serial sampling is required, such as monitoring disease progression or development of resistance mutations to current targeted therapies. Liquid biopsies also have a potential role in identifying patients at risk of relapse post treatment and as a component of future lung cancer screening protocols. Rapid developments have led to multiple platforms for isolating circulating tumor cells (CTCs) and detecting circulating tumor DNA (ctDNA); however, standardization is lacking, especially in lung carcinoma. Additionally, clonal hematopoiesis of uncertain clinical significance must be taken into consideration in genetic sequencing, as it introduces the potential for false positives. Various biomarkers have been investigated in liquid biopsies; however, in this review, we will concentrate on the current use of ctDNA and CTCs, focusing on the clinical relevance, current and possible future applications and limitations of each.

Leptomeningeal Metastases from Solid Tumors: Recent Advances in Diagnosis and Molecular Approaches

Leptomeningeal metastases (LM) from solid tumors represent an unmet need of increasing importance due to an early use of MRI for diagnosis and improvement of outcome of some molecular subgroups following targeted agents and immunotherapy. In this review, we first discussed factors limiting the efficacy of targeted agents in LM, such as the molecular divergence between primary tumors and CNS lesions and CNS barriers at the level of the normal brain, brain tumors and CSF. Further, we reviewed pathogenesis and experimental models and modalities, such as MRI (with RANO and ESO/ESMO criteria), CSF cytology and liquid biopsy, to improve diagnosis and monitoring following therapy. Efficacy and limitations of targeted therapies for LM from EGFR-mutant and ALK-rearranged NSCLC, HER2-positive breast cancer and BRAF-mutated melanomas are reported, including the use of intrathecal administration or modification of traditional cytotoxic compounds. The efficacy of checkpoint inhibitors in LM from non-druggable tumors, in particular triple-negative breast cancer, is discussed. Last, we focused on some recent techniques to improve drug delivery.

Single-Cell Characterization of the Immune Microenvironment of Melanoma Brain and Leptomeningeal Metastases

PURPOSE

Melanoma brain metastases (MBM) and leptomeningeal melanoma metastases (LMM) are two different manifestations of melanoma CNS metastasis. Here, we used single-cell RNA sequencing (scRNA-seq) to define the immune landscape of MBM, LMM, and melanoma skin metastases.

EXPERIMENTAL DESIGN

scRNA-seq was undertaken on 43 patient specimens, including 8 skin metastases, 14 MBM, and 19 serial LMM specimens. Detailed cell type curation was performed, the immune landscapes were mapped, and key results were validated by IHC and flow cytometry. Association analyses were undertaken to identify immune cell subsets correlated with overall survival.

RESULTS

The LMM microenvironment was characterized by an immune-suppressed T-cell landscape distinct from that of brain and skin metastases. An LMM patient with long-term survival demonstrated an immune repertoire distinct from that of poor survivors and more similar to normal cerebrospinal fluid (CSF). Upon response to PD-1 therapy, this extreme responder showed increased levels of T cells and dendritic cells in their CSF, whereas poor survivors showed little improvement in their T-cell responses. In MBM patients, therapy led to increased immune infiltrate, with similar T-cell transcriptional diversity noted between skin metastases and MBM. A correlation analysis across the entire immune landscape identified the presence of a rare population of dendritic cells (DC3) that was associated with increased overall survival and positively regulated the immune environment through modulation of activated T cells and MHC expression.

CONCLUSIONS

Our study provides the first atlas of two distinct sites of melanoma CNS metastases and defines the immune cell landscape that underlies the biology of this devastating disease.

Melanoma brain metastasis presentation, treatment, and outcomes in the age of targeted and immunotherapies

BACKGROUND

Historically, the prognosis for patients who have melanoma brain metastasis (MBM) has been dismal. However, breakthroughs in targeted and immunotherapies have improved long-term survival in those with advanced melanoma. Therefore, MBM presentation, prognosis, and the use of multimodality central nervous system (CNS)-directed treatment were reassessed.

METHODS

In this retrospective study, the authors evaluated patients with MBM who received treatment at Memorial Sloan Kettering Cancer Center between 2010 and 2019. Kaplan-Meier methodology was used to describe overall survival (OS). Recursive partitioning analysis and time-dependent multivariable Cox modeling were used to assess prognostic variables and to associate CNS-directed treatments with OS.

RESULTS

Four hundred twenty-five patients with 2488 brain metastases were included. The median OS after an MBM diagnosis was 8.9 months (95% CI, 7.9-11.3 months). Patients who were diagnosed with MBM between 2015 and 2019 experienced longer OS compared to those who were diagnosed between 2010 and 2014 (OS, 13.0 months [95% CI, 10.47-17.06 months] vs 7.0 months [95% CI, 6.1-8.3 months]; P = .0003). Prognostic multivariable modeling significantly associated shortened OS independently with leptomeningeal dissemination (P < .0001), increasing numbers of brain metastases at diagnosis (P < .0001), earlier MBM diagnosis year (P = .0008), higher serum levels of lactate dehydrogenase (P < .0001), receipt of immunotherapy before MBM diagnosis (P = .003), and the presence of extracranial disease (P = .02). The use of different CNS-directed treatment modalities was associated with presenting symptoms, diagnosis year, number and size of brain metastases, and the presence of extracranial disease. Multivariable analysis demonstrated improved survival for patients who underwent craniotomy (P = .01).

CONCLUSIONS

The prognosis for patients with MBM has improved within the last 5 years, coinciding with the approval of PD-1 immune checkpoint blockade and combined BRAF/MEK targeting. Improving survival reflects and may influence the willingness to use aggressive multimodality treatment for MBM.

LAY SUMMARY

Historically, melanoma brain metastases (MBM) have carried a poor survival prognosis of 4 to 6 months; however, the introduction of immunotherapy and targeted precision medicines has altered the survival curve for advanced melanoma. In this large, single-institution, contemporary cohort, the authors demonstrate a significant increase in survival of patients with MBM to 13 months within the last 5 years of the study. A worse prognosis for patients with MBM was significantly associated with the number of metastases at diagnosis, previous exposure to immunotherapy, spread of disease to the leptomeningeal compartment, serum lactate dehydrogenase elevation, and the presence of extracranial disease. The current age of systemic treatments has also been accompanied by shifts in the use of central nervous system-directed therapies.

Metastatic Melanoma With Leptomeningeal Disease

Leptomeningeal disease in patients with melanoma historically portends a grim prognosis, with median survival measured in weeks to months. The advent of effective immunotherapy and targeted agents may modify the outcome of such patients. This case report describes a 43-year-old patient diagnosed with stage IIIa BRAF-positive cutaneous melanoma in 2012 who subsequently developed leptomeningeal involvement as her sole site of melanotic metastasis. She received multiple systemic therapies and radiotherapy and survived 2.5 years after her diagnosis with central nervous system involvement. This case report highlights the importance of a multidisciplinary team and the advent of effective agents, which offers the potential for significantly improved outcomes for patients with metastatic melanoma involving the central nervous system.

Treatment Options for Leptomeningeal Metastases of Solid Cancers: Literature Review and Personal Experience

Leptomeningeal metastases (LM) may complicate the clinical course of any solid cancer or hematological malignancy. Diagnosis of such cases requires a multifaceted approach, including careful evaluation of the clinical history, detailed neurological examination, advanced imaging studies, and related laboratory data analysis. Therapeutic options for management of LM have not been standardized yet. Conventional intrathecal chemotherapy with or without involved-field fractionated radiotherapy has only modest efficacy, and the prognosis of most patients remains grim. Therefore, development of new, more aggressive multimodal treatment strategies is definitely needed. Immune checkpoint inhibitors-in particular, molecular targeted therapy-have demonstrated promising results in selected groups of patients. There may be an important role for stereotactic radiosurgery as well. Because organization of prospective randomized multi-institutional trials on treatment of LM of solid cancers may be problematic, practical guidelines for optimal therapeutic strategies in such cases should be established on the basis of integrated results of small-scale prospective and retrospective studies.

Leptomeningeal disease in melanoma patients: An update to treatment, challenges, and future directions

In February 2018, the Melanoma Research Foundation and the Moffitt Cancer Center hosted the Second Summit on Melanoma Central Nervous System Metastases in Tampa, Florida. The meeting included investigators from multiple academic centers and disciplines. A consensus summary of the progress and challenges in melanoma parenchymal brain metastases was published (Eroglu et al., Pigment Cell & Melanoma Research, 2019, 32, 458). Here, we will describe the current state of basic, translational, clinical research, and therapeutic management, for melanoma patients with leptomeningeal disease. We also outline key challenges and barriers to be overcome to make progress in this deadly disease.

Melanoma Brain Metastases in the Era of Target Therapies: An Overview

Malignant melanoma is the third most common type of tumor that causes brain metastases. Patients with cerebral involvement have a dismal prognosis and their treatment is an unmet medical need. Brain involvement is a multistep process involving several signaling pathways such as Janus kinase/signal Transducer and Activator of Transcription (JAK/STAT), Phosphoinositide 3-kinase/Protein Kinase B (PI3K/AKT), Vascular Endothelial Growth Factor and Phosphatase and Tensin Homolog (PTEN). Recently therapy that targets the MAPK signaling (BRAF/MEK inhibitors) and immunotherapy (anti-CTLA4 and anti-PD1 agents) have changed the therapeutic approaches to stage IV melanoma. In contrast, there are no solid data about patients with brain metastases, who are usually excluded from clinical trials. Retrospective data showed that BRAF-inhibitors, alone or in combination with MEK-inhibitors have interesting clinical activity in this setting. Prospective data about the combinations of BRAF/MEK inhibitors have been recently published, showing an improved overall response rate. Short intracranial disease control is still a challenge. Several attempts have been made in order to improve it with combinations between local and systemic therapies. Immunotherapy approaches seem to retain promising activity in the treatment of melanoma brain metastasis as showed by the results of clinical trials investigating the combination of anti-CTL4 (Ipilimumab) and anti-PD1(Nivolumab). Studies about the combination or the sequential approach of target therapy and immunotherapy are ongoing, with immature results. Several clinical trials are ongoing trying to explore new approaches in order to overcome tumor resistance. At this moment the correct therapeutic choices for melanoma with intracranial involvement is still a challenge and new strategies are needed.

Proteomic Analysis of CSF from Patients with Leptomeningeal Melanoma Metastases Identifies Signatures Associated with Disease Progression and Therapeutic Resistance

PURPOSE

The development of leptomeningeal melanoma metastases (LMM) is a rare and devastating complication of the late-stage disease, for which no effective treatments exist. Here, we performed a multi-omics analysis of the cerebrospinal fluid (CSF) from patients with LMM to determine how the leptomeningeal microenvironment shapes the biology and therapeutic responses of melanoma cells.

EXPERIMENTAL DESIGN

A total of 45 serial CSF samples were collected from 16 patients, 8 of these with confirmed LMM. Of those with LMM, 7 had poor survival (<4 months) and one was an extraordinary responder (still alive with survival >35 months). CSF samples were analyzed by mass spectrometry and incubated with melanoma cells that were subjected to RNA sequencing (RNA-seq) analysis. Functional assays were performed to validate the pathways identified.

RESULTS

Mass spectrometry analyses showed the CSF of most patients with LMM to be enriched for pathways involved in innate immunity, protease-mediated damage, and IGF-related signaling. All of these were anticorrelated in the extraordinary responder. RNA-seq analysis showed CSF to induce PI3K/AKT, integrin, B-cell activation, S-phase entry, TNFR2, TGFβ, and oxidative stress responses in the melanoma cells. ELISA assays confirmed that TGFβ expression increased in the CSF of patients progressing with LMM. CSF from poorly responding patients conferred tolerance to BRAF inhibitor therapy in apoptosis assays.

CONCLUSIONS

These analyses identified proteomic/transcriptional signatures in the CSF of patients who succumbed to LMM. We further showed that the CSF from patients with LMM has the potential to modulate BRAF inhibitor responses and may contribute to drug resistance.See related commentary by Glitza Oliva and Tawbi, p. 2083.

Neoplastic meningitis in solid tumours: Updated review of diagnosis, prognosis, therapeutic management, and future directions

Neoplastic meningitis (NM) is a relatively frequent metastatic complication of cancer associated with high levels of neurological morbidity and generally poor prognosis. It appears in 5%-15% of patients with solid tumours, the most frequent being breast and lung cancer and melanoma. Symptoms are caused by involvement of the cerebral hemispheres, cranial nerves, spinal cord, and nerve roots, and are often multifocal or present with signs and symptoms of intracranial hypertension. The main diagnostic tools are the neurological examination, brain and spinal cord contrast-enhanced magnetic resonance imaging, and cerebrospinal fluid analysis including cytology, although studies have recently been conducted into the detection of tumour cells and DNA in the cerebrospinal fluid, which increases diagnostic sensitivity. With the currently available therapies, treatment aims not to cure the disease, but to delay and ameliorate the symptoms and to preserve quality of life. Treatment of NM involves a multimodal approach that may include radiotherapy, intrathecal and/or systemic chemotherapy, and surgery. Treatment should be individualised, and is based mainly on clinical practice guidelines and expert opinion. Promising clinical trials are currently being conducted to evaluate drugs with molecular and immunotherapeutic targets. This article is an updated review of NM epidemiology, clinical presentation, diagnosis, prognosis, management, and treatment; it is aimed at general neurologists and particularly at neurologists practicing in hospital settings with oncological patients.

Melanoma Brain Metastases: Local Therapies, Targeted Therapies, Immune Checkpoint Inhibitors and Their Combinations-Chances and Challenges

Recent phase II trials have shown that BRAF/MEK inhibitors and immune checkpoint inhibitors are active in patients with melanoma brain metastases (MBM), reporting intracranial disease control rates of 50-75%. Furthermore, retrospective analyses suggest that combining stereotactic radiosurgery with immune checkpoint inhibitors or BRAF/MEK inhibitors prolongs overall survival. These data stress the need for inter- and multidisciplinary cooperation that takes into account the individual prognostic factors in order to establish the best treatment for each patient. Although the management of MBM has dramatically improved, a substantial number of patients still progress and die from brain metastases. Therefore, there is an urgent need for prospective studies in patients with MBM that focus on treatment combinations and sequences, new treatment strategies, and biomarkers of treatment response. Moreover, further research is needed to decipher brain-specific mechanisms of therapy resistance.

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.

Leptomeningeal disease: current diagnostic and therapeutic strategies

Leptomeningeal disease has become increasingly prevalent as novel therapeutic interventions extend the survival of cancer patients. Although a majority of leptomeningeal spread occurs secondary to breast cancer, lung cancer, and melanoma, a wide variety of malignancies have been reported as primary sources. Symptoms on presentation are equally diverse, often involving a combination of neurological deficits with the possibility of obstructive hydrocephalus. Diagnosis is definitively made via cerebrospinal fluid cytology for malignant cells, but neuro-imaging with high quality T1-weighted magnetic resonance imaging can aid diagnosis and localization. While leptomeningeal disease is still a terminal, late-stage complication, a variety of treatment modalities, such as intrathecal chemotherapeutics and radiation therapy, have improved median survival from 4–6 weeks to 3–6 months. Positive prognosticative factors for survival include younger age, high performance scores, and controlled systemic disease. In looking to the future, diagnostics that improve early detection and chemotherapeutics tailored to the primary malignancy will likely be the most significant advances in improving survival.

Meningeal melanomatosis following discontinuation of dabrafenib: implications for the maintenance of long-term complete remission

A subset of 10-20% of patients under continuous BRAF inhibitor monotherapy achieve long-term progression-free and overall survival. Definitive criteria for the safe cessation of BRAF inhibitor monotherapy in treatment-responsive melanoma patients are lacking. We report a patient who remained in complete remission (CR) for 5 years under dabrafenib. The treatment was withdrawn because of concerns about cardiac toxicity. Four months thereafter the patient developed neurological symptoms, including diplopia and bilateral visual loss. Meningeal melanomatosis and parenchymal brain metastases were diagnosed. Extracerebral metastases were excluded. Reinduction of dabrafenib, combined with trametinib, led to the rapid relief of the neurological symptoms, and a partial remission was confirmed radiologically. Unfortunately, the response was not maintained and the patient died 9 months later. This observation demonstrates that discontinuation of BRAF inhibition can result in loss of disease control. On the basis of this observation, we suggest that BRAF-targeted therapy should be withdrawn only when the risks of continued treatment exceed the risk for disease relapse. However, future studies are urgently required to confirm and quantify the risk for rapid disease relapse following withdrawal of BRAF inhibitor monotherapy.

Leptomeningeal Disease and the Evolving Role of Molecular Targeted Therapy and Immunotherapy

BACKGROUND

Leptomeningeal disease (LMD) is a complication that results from solid tumor metastasis. Prognosis is extremely poor. As therapeutic options for solid tumors improve, the rate of LMD continues to increase. Until recently, treatment has been limited to radiation therapy, intrathecal chemotherapy, and systemic chemotherapy, with an overall survival of 2-3 months. Targeted molecular therapy and immunotherapies are promising new options for increasing overall survival and clinical improvement; however, optimal clinical management remains unknown.

METHODS

In this review, we discuss targeted molecular therapy and immunotherapy treatment options for LMD resulting from primary lung, breast, and melanoma tumors. In addition, we summarize dosing strategies, overall survival, clinical outcomes, and novel approaches to treatment.

RESULTS

Our review indicates a deficiency in the current literature. Presently, intrathecal trastuzumab administration may be an effective option for patients with HER2-positive breast cancer. BRAF inhibitors and cytotoxic T lymphocyte-associated antigen-4 targets have shown promising results in LMD resulting from melanoma. Finally, tyrosine kinase inhibitors may increase overall survival in epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer. Pulsatile drug administration or dual therapy may be beneficial for patients who progress to LMD while being treated with EGFR targets for their primary malignancy.

CONCLUSION

Targeted molecular therapy and immunotherapy in LMD may provide favorable treatment options. Current literature is lacking in safety, efficacy, and overall response rates from the use of targeted therapy. Research is needed to draw significant conclusions about the most appropriate therapy for patients with LMD.