Evolving treatment options for melanoma brain metastases

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.

Stereotactic body radiotherapy as a viable treatment on extracranial oligometastases in melanoma patients: a retrospective multicentric study

Introduction

Stereotactic radiotherapy (SBRT) potentially has a role in the management of oligometastatic melanoma. However, literature with data specific to this management is very limited. The objectives of this study were to evaluate the time to local control (LC) of extra-cranial melanoma metastases after SBRT treatment and to help establish if SBRT is a useful therapy for oligometastatic melanoma.

Methods

A retrospective study was conducted with data collected from two referral centers in France between 2007 and 2020. The oligometastatic status of patients was reported based on the latest recommendations with a maximum of three lesions prior to treatment.

Results

A total of 69 patients receiving SBRT for 88 oligometastatic melanoma metastases were included. The median follow-up time was 42.6 months. Most patients were treated for metachronous oligometastatic lesions. Occurrence of oligoprogression, oligorecurrence, and oligopersistence was reported in 42.0%, 39.1%, and 17.4% of cases, respectively. Treated lesions were mostly pulmonary (40.6%), followed by lymph node (34.8%) and hepatic sites (24.6%). Progression-free survival at 1, 2, and 3 years were 47.0% (35-59), 27.0% (16-39), and 25.0% (15.0-37.0), respectively. Time to LC rates at 1, 2, and 3 years were 94.2% (87.0-98.1), 90.3% (81.3-96.1), and 90.3% (81.3-96.1), respectively. Overall survival at 1, 2, and 3 years were 87% (76.0-93.0), 74.0% (76.0-93.0), and 61.0% (47.0-73.0), respectively. Only 17.4% of patients experienced acute, grade 1 or grade 2 toxicities with no reports of grade 3 or higher toxicities.

Conclusion

SBRT demonstrated efficacy in managing melanoma patients with extracranial oligometastases and showed an overall low toxicity profile. Future randomized studies are needed to establish the role of SBRT in therapeutic approaches for patients with oligometastatic melanoma.

Melanoma Brain Metastases: A Systematic Review of Opportunities for Earlier Detection, Diagnosis, and Treatment

Introduction: Melanoma continues to represent the most serious skin cancer worldwide. However, few attempts have been made to connect the body of research on advanced melanoma. In the present review, we report on strides made in the diagnosis and treatment of intracranial metastatic melanoma. Methods: Relevant Cochrane reviews and randomized-controlled trials published by November 2022 were systematically retrieved from the Cochrane Library, EMBASE, and PubMed databases (N = 27). Search and screening methods adhered to the 2020 revision of the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Results: Although the research surrounding the earlier detection of melanoma brain metastasis is scarce, several studies have highlighted specific markers associated with MBM. Such factors include elevated BRAFV600 mutant ctDNA, high LDH concentration, and high IGF-1R. The approach to treating MBM is moving away from surgery and toward nonsurgical management, namely, a combination of stereotactic radiosurgery (SRS) and immunotherapeutic agents. There is an abundance of emerging research seeking to identify and improve both novel and established treatment options and diagnostic approaches for MBM, however, more research is still needed to maximize the clinical efficacy, especially for new immunotherapeutics. Conclusions: Early detection is optimal for the efficacy of treatment and MBM prognosis. Current treatment utilizes chemotherapies and targeted therapies. Emerging approaches emphasize biomarkers and joint treatments. Further exploration toward preliminary identification, the timing of therapies, and methods to ameliorate adverse treatment effects are needed to advance MBM patient care.

Systemic treatments for breast cancer brain metastasis

Breast cancer (BC) is the most common cancer in females and BC brain metastasis (BCBM) is considered as the second most frequent brain metastasis. Although the advanced treatment has significantly prolonged the survival in BC patients, the prognosis of BCBM is still poor. The management of BCBM remains challenging. Systemic treatments are important to maintain control of central nervous system disease and improve patients' survival. BCBM medical treatment is a rapidly advancing area of research. With the emergence of new targeted drugs, more options are provided for the treatment of BM. This review features currently available BCBM treatment strategies and outlines novel drugs and ongoing clinical trials that may be available in the future. These treatment strategies are discovered to be more efficacious and potent, and present a paradigm shift in the management of BCBMs.

The effect of organ-specific tumor microenvironments on response patterns to immunotherapy

Immunotherapy, particularly immune checkpoint inhibitors, have become widely used in various settings across many different cancer types in recent years. Whilst patients are often treated on the basis of the primary cancer type and clinical stage, recent studies have highlighted disparity in response to immune checkpoint inhibitors at different sites of metastasis, and their impact on overall response and survival. Studies exploring the tumor immune microenvironment at different organ sites have provided insights into the immune-related mechanisms behind organ-specific patterns of response to immunotherapy. In this review, we aimed to highlight the key learnings from clinical studies across various cancers including melanoma, lung cancer, renal cell carcinoma, colorectal cancer, breast cancer and others, assessing the association of site of metastasis and response to immune checkpoint inhibitors. We also summarize the key clinical and pre-clinical findings from studies exploring the immune microenvironment of specific sites of metastasis. Ultimately, further characterization of the tumor immune microenvironment at different metastatic sites, and understanding the biological drivers of these differences, may identify organ-specific mechanisms of resistance, which will lead to more personalized treatment approaches for patients with innate or acquired resistance to immunotherapy.

The different faces of metastatic melanoma in the gastrointestinal tract

Melanoma is the most aggressive form of skin cancer, with tendency to spread to any organ of the human body, including the gastrointestinal tract (GIT). The diagnosis of metastases to the GIT can be difficult, as they may be clinically silent for somewhile and may occur years after the initial melanoma diagnosis. CT imaging remains the standard modality for staging and surveillance of melanoma patients, and in most cases, it will be the first imaging modality to identify GIT lesions. However, interpretation of CT studies in patients with melanoma can be challenging as lesions may be subtle and random in distribution, as well as sometimes mimicking other conditions. Even so, early diagnosis of GIT metastases is critical to avoid emergency hospitalisations, whilst surgical intervention can be curative in some cases. In this review, we illustrate the various imaging presentations of melanoma metastases within the GIT, discuss the clinical aspects and offer advice on investigation and management. We offer tips intended to aid radiologists in their diagnostic skills and interpretation of melanoma imaging scans.

Genetic and Clinical Characteristics of ARID1A Mutated Melanoma Reveal High Tumor Mutational Load without Implications on Patient Survival

Simple Summary

Melanoma is a highly malignant skin cancer with the highest mortality of all cutaneous tumors. Relevant genetic events have been identified, which shape the tumor and also the response to treatment. Recurrent ARID1A mutations have been identified, which are associated with improved outcomes to immune checkpoint inhibition in various tumors. Not much was known about the role of ARID1A mutations in melanoma to date. We investigated the largest cohort of ARID1A mutated melanoma to date and were able to show that despite a high mutational load the described beneficial treatment response is not apparent in melanoma.

Abstract

(1) Background: Melanoma has the highest mortality of all cutaneous tumors, despite recent treatment advances. Many relevant genetic events have been identified in the last decade, including recurrent ARID1A mutations, which in various tumors have been associated with improved outcomes to immunotherapy. (2) Methods: Retrospective analysis of 116 melanoma samples harboring ARID1A mutations. Assessment of clinical and genetic characteristics was performed as well as correlations with treatment outcome applying Kaplan–Meier (log-rank test), Fisher’s exact and Chi-squared tests. (3) Results: The majority of ARID1A mutations were in cutaneous and occult melanoma. ARID1A mutated samples had a higher number of mutations than ARID1A wild-type samples and harbored UV-mutations. A male predominance was observed. Many samples also harbored NF1 mutations. No apparent differences were noted between samples harboring genetically inactivating (frame-shift or nonsense) mutations and samples with other mutations. No differences in survival or response to immunotherapy of patients with ARID1A mutant melanoma were observed. (4) Conclusions: ARID1A mutations primarily occur in cutaneous melanomas with a higher mutation burden. In contrast to findings in other tumors, our data does not support ARID1A mutations being a biomarker of favorable response to immunotherapies in melanoma. Larger prospective studies would still be warranted.

NF1-mutated melanomas reveal distinct clinical characteristics depending on tumour origin and respond favourably to immune checkpoint inhibitors

BACKGROUND

NF1-mutated tumours represent a small subset (10-15%) of melanomas, not sufficiently analysed in large clinical cohorts. This study investigated the largest multicentre collection of NF1-mutated melanomas to date.

METHODS

This study analysed a multicentre tumour tissue sample cohort from 266 patients with NF1-mutated melanoma. Targeted next-generation sequencing of the TERT promoter and 29 relevant melanoma genes was performed. Survival was compared with NF1 wild-type cohorts from the Tissue Registry in Melanoma project (n = 432).

RESULTS

Most NF1-mutated melanoma arose in the head-and-neck region of patients >60 years. NF1 alterations were frequently inactivating, primarily non-sense, less frequently truncating mutations. Non-inactivating NF1 mutations more frequently co-occurred with activating BRAF and RAS mutations. NF1-mutated tumours had higher numbers of gene mutations and UV signature C>T and CC>TT transitions than BRAF, RAS and triple wild-type melanomas. NF1-mutated acral and mucosal melanomas harboured a different mutation signature and were frequent in women (69% and 83%, respectively), differing from non-acral cutaneous NF1-mutated melanomas (men 73%, women 27%). Overall survival in stage IV disease was comparable for patients with NF1-mutated or wild-type melanoma. However, in patients receiving first-line immune checkpoint inhibitor treatment, better median overall survival (mOS) was observed for NF1-mutated than wild-type tumours (mOS = not reached vs mOS = 25.82, p = 0.0154, n = 80 and 432, respectively).

CONCLUSIONS

Cutaneous, acral and mucosal NF1-mutated melanomas vary in clinical and genetic characteristics and demonstrate a favourable outcome on immune checkpoint inhibition therapy.

Real-life data for first-line combination immune-checkpoint inhibition and targeted therapy in patients with melanoma brain metastases

BACKGROUND

Melanoma brain metastases (MBM) have a poor prognosis. Systemic treatments that have improved outcomes in advanced melanoma have been shown to have an intracranial (IC) effect. We studied the efficacy and outcomes of combined immune checkpoint inhibitor ipilimumab/nivolumab (Combi-ICI) or targeted therapy (Combi-TT) as first-line treatment in MBM.

METHODS

MBM patients treated with Combi-ICI or Combi-TT within 3 months after MBM diagnosis. Endpoints were progression-free survival (PFS) and overall survival (OS).

RESULTS

53 patients received Combi-ICI, 32% had symptomatic MBM and 33.9% elevated LDH. 71.7% required local treatment. The disease control rate was 60.3%. IC response rate (RR) was 43.8% at 3-months with durable responses at 6- (46.5%) and 12-months (53.1%). Extracranial (EC) RR was 44.7% at 3-months and 50% at 12-months. Median PFS was 9.6 months (95% CI 3.6-NR) and median overall survival (mOS) 44.8 months (95% CI; 26.2-NR). 63 patients received Combi-TT, 55.6% of patients had symptomatic MBM, 57.2% of patients had elevated LDH and 68.3% of patients required local treatment. The disease control rate was 60.4%. ICRR was 50% at 3-months, but dropped at 6-months (20.9%). ECRR was 69.2% at 3-months and 17.6% at 12-months. Median PFS was 5.8 months (95% CI 4.2-7.6) and mOS 14.2 months (95% CI 8.99-26.8). In BRAFV600 patients, 26.7% of patients received Combi-ICI and 73.3% Combi-TT with OS (p = 0.0053) and mPFS (p = 0.03) in favour to Combi-ICI.

CONCLUSION

Combi-ICI showed prolonged mOS with sustainable IC and EC responses. Despite the initially increased efficacy, Combi-TT responses at 12 months were low. Combi-ICI appeared superior to Combi-TT for OS and PFS in BRAFV600 patients. Other clinical factors are determinants for first-line treatment choice.

The combined use of steroids and immune checkpoint inhibitors in brain metastasis patients: a systematic review and meta-analysis

BACKGROUND

Immune checkpoint inhibitors (ICI) have been a breakthrough for selected cancer patients, including those with brain metastases (BMs). Likewise, steroids have been an integral component of symptomatic management of BM patients. However, clinical evidence on the interaction between ICI and steroids in BM patients is conflicting and has not adequately been summarized thus far. Hence, the aim of this study was to perform a systematic literature review and meta-analysis on the association between steroid use and overall survival (OS) in BM patients receiving ICI.

METHODS

A systematic literature search was performed. Pooled effect estimates were calculated using random-effects models across included studies.

RESULTS

After screening 1145 abstracts, 15 observational studies were included. Fourteen studies reported sufficient data for meta-analysis, comprising 1102 BM patients of which 32.1% received steroids. In the steroid group, median OS ranged from 2.9 to 10.2 months. In the nonsteroid group, median OS ranged from 4.9 to 25.1 months. Pooled results demonstrated significantly worse OS (HR = 1.84, 95% CI 1.22-2.77) and systemic progression-free survival (PFS; HR = 2.00, 95% CI 1.37-2.91) in the steroid group. Stratified analysis showed a consistent effect across the melanoma subgroup; not in the lung cancer subgroup. No significant association was shown between steroid use and intracranial PFS (HR = 1.31, 95% CI 0.42-4.07).

CONCLUSIONS

Administration of steroids was associated with significantly worse OS and PFS in BM patients receiving ICI. Further research on dose, timing, and duration of steroids is needed to elucidate the cause of this association and optimize outcomes in BM patients receiving ICI.

A Systems Approach to Brain Tumor Treatment

Brain tumors are among the most lethal tumors. Glioblastoma, the most frequent primary brain tumor in adults, has a median survival time of approximately 15 months after diagnosis or a five-year survival rate of 10%; the recurrence rate is nearly 90%. Unfortunately, this prognosis has not improved for several decades. The lack of progress in the treatment of brain tumors has been attributed to their high rate of primary therapy resistance. Challenges such as pronounced inter-patient variability, intratumoral heterogeneity, and drug delivery across the blood-brain barrier hinder progress. A comprehensive, multiscale understanding of the disease, from the molecular to the whole tumor level, is needed to address the intratumor heterogeneity resulting from the coexistence of a diversity of neoplastic and non-neoplastic cell types in the tumor tissue. By contrast, inter-patient variability must be addressed by subtyping brain tumors to stratify patients and identify the best-matched drug(s) and therapies for a particular patient or cohort of patients. Accomplishing these diverse tasks will require a new framework, one involving a systems perspective in assessing the immense complexity of brain tumors. This would in turn entail a shift in how clinical medicine interfaces with the rapidly advancing high-throughput (HTP) technologies that have enabled the omics-scale profiling of molecular features of brain tumors from the single-cell to the tissue level. However, several gaps must be closed before such a framework can fulfill the promise of precision and personalized medicine for brain tumors. Ultimately, the goal is to integrate seamlessly multiscale systems analyses of patient tumors and clinical medicine. Accomplishing this goal would facilitate the rational design of therapeutic strategies matched to the characteristics of patients and their tumors. Here, we discuss some of the technologies, methodologies, and computational tools that will facilitate the realization of this vision to practice.

Cutaneous melanoma in children and adolescents: The EXPeRT/PARTNER diagnostic and therapeutic recommendations

Cutaneous melanoma is rare in children and, like other very rare pediatric tumors, it suffers from a shortage of knowledge and clinical expertise. The clinical management of pediatric melanoma is often challenging. Its clinical and pathological diagnosis may be difficult, and there is no standard treatment. In the absence of specific treatment guidelines, young patients are generally treated following the same principle as for adults, but concern remains about their access to clinical trials and new drugs, which have been shown to dramatically change the natural history of advanced melanoma. This paper presents the internationally recognized recommendations for the diagnosis and treatment of children and adolescents with cutaneous melanoma, established by the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) within the EU-funded project called PARTNER (Paediatric Rare Tumours Network - European Registry). Main recommendations for melanoma are to discuss pediatric patients in multidisciplinary teams that include both pediatric oncologists and specialists in adult melanoma; to enroll patients in prospective trials, if available; to collect data in national-international databases; and to develop an effective international collaboration between pediatric and adult melanoma groups in order to facilitate the transfer of potentially effective new agents from the adult to the pediatric setting.

Recent Progress in the Design and Medical Application of In Situ Self-Assembled Polypeptide Materials

Inspired by molecular self-assembly, which is ubiquitous in natural environments and biological systems, self-assembled peptides have become a research hotspot in the biomedical field due to their inherent biocompatibility and biodegradability, properties that are afforded by the amide linkages forming the peptide backbone. This review summarizes the biological advantages, principles, and design strategies of self-assembled polypeptide systems. We then focus on the latest advances in in situ self-assembly of polypeptides in medical applications, such as oncotherapy, materials science, regenerative medicine, and drug delivery, and then briefly discuss their potential challenges in clinical treatment.

Outcomes after stereotactic radiosurgery of brain metastases in patients with malignant melanoma and validation of the melanoma molGPA

INTRODUCTION

Malignant melanoma is the third most common primary in the diagnosis of brain metastases. Stereotactic radiosurgery (SRS) is a well-established treatment option in limited brain disease. We analyzed outcomes of SRS with a particular focus on the graded prognostic assessment (GPA, melanoma molGPA), prognostic factors, and toxicity.

METHODS

We evaluated 173 brain metastases in 83 patients with malignant melanoma. All were treated with SRS median dose of 20 Gy prescribed to the 80 or 100% isodose line between 2002 and 2019. All patients were followed-up regularly, including contrast-enhanced brain imaging as well as clinical examination, initially 6 weeks after treatment, then in quarterly follow-up.

RESULTS

The median age was 61 years (range 27-80); 36 female and 47 male patients were treated. After a median follow-up of 5.7 months, median OS (overall survival) was 9.7 months 95%-KI 4.7-14.7). LC (local control) at 6 months, 12, 24 months was 89%, 86%, and 72%, respectively (median was not reached). Median DBC (distant brain control) was 8.2 months (95%-KI 4.7-11.7). For OS, a KPS ≥ 80%, a positive BRAF mutation status, a small PTV (planning target volume), the absence of extracranial metastases, as well as a GPA and melanoma molGPA > 2 were prognostic factors. In the MVA, a small PTV and a melanoma molGPA > 2 remained significant.

CONCLUSION

The present survival outcomes support the use of the disease-specific melanoma molGPA as reliable prognostic score. Favorable outcomes for SRS compared to other studies were observed. In the treatment of brain metastases of malignant melanoma patients, a multidisciplinary approach consisting of surgery, SRS, chemotherapy, and immunotherapy should be considered.

Ipilimumab and Stereotactic Radiosurgery with CyberKnife® System in Melanoma Brain Metastases: A Retrospective Monoinstitutional Experience

Simple Summary

Retrospective studies have shown a survival advantage in combining ipilimumab with radiotherapy in patients with melanoma brain metastases (MBMs). However, these studies did not clarify the correct timing between the two methods. The aims of our study were to demonstrate the efficacy and toxicity of stereotactic radiotherapy/radiosurgery on MBMs in combination with ipilimumab and estimate the correct timing of treatments to improve patients’ outcomes.

Abstract

The median overall survival (OS) and local control (LC) of patients with melanoma brain metastases (MBMs) are poor even with immune checkpoint inhibitors and/or radiotherapy (RT). The aims of the study were to evaluate the association and timing of stereotactic radiotherapy (SRT)/radiosurgery (SRS) performed with the CyberKnife^® System and ipilimumab (IPI). A total of 63 MBMs patients were analyzed: 53 received RT+IPI and 10 RT alone. Therefore, the patients were divided into four groups: RT PRE-PI (>4 weeks before IPI) (18), RT CONC-IPI (4 weeks before/between first and last cycle/within 3 months of last cycle of IPI) (20), RT POST-IPI (>3 months after IPI) (15), and NO-IPI (10). A total of 127 lesions were treated: 75 with SRS (one fraction) and 24 with SRT (three to five fractions). The median follow-up was 10.6 months. The median OS was 10.6 months for all patients, 10.7 months for RT+IPI, and 3.3 months for NO-IPI (p = 0.96). One-year LC was 50% for all patients, 56% for RT+IPI, and 18% for NO-IPI (p = 0.08). The 1-year intracranial control was 45% for all patients, 44% for RT+IPI, and 51% for NO-IPI (p = 0.73). IPI with SRS/SRT in MBMs treatment could improve LC. However, the impact and timing of the two modalities on patients’ outcomes are still unclear.

Melanoma brain metastases: Biological basis and novel therapeutic strategies

The development of brain metastases is the deadliest complication of advanced melanoma and has long been associated with a dismal prognosis. The recent years have seen incredible progress in the development of therapies for melanoma brain metastases (MBM), with both targeted therapies (the BRAF-MEK inhibitor combination) and immune checkpoint inhibitors (the anti-CTLA-4, anti-PD-1 combination) showing impressive levels of activity. Despite this, durations of response for these therapies remain lower at intracranial sites of metastasis compared to extracranial metastases and it has been suggested that there are unique features of the brain microenvironment that contribute to therapeutic escape. In this review, we outline the latest research into the biology and pathophysiology of melanoma brain metastasis development and progression. We then discuss the current status of clinical trial that are open to patients with MBM and end by describing the ongoing challenges for the field.

The mutational landscape of melanoma brain metastases presenting as the first visceral site of recurrence

Brain metastases are a major cause of melanoma-related mortality and morbidity. We undertook whole-exome sequencing of 50 tumours from patients undergoing surgical resection of brain metastases presenting as the first site of visceral disease spread and validated our findings in an independent dataset of 18 patients. Brain metastases had a similar driver mutational landscape to cutaneous melanomas in TCGA. However, KRAS was the most significantly enriched driver gene, with 4/50 (8%) of brain metastases harbouring non-synonymous mutations. Hotspot KRAS mutations were mutually exclusive from BRAFV600, NRAS and HRAS mutations and were associated with a reduced overall survival from the resection of brain metastases (HR 10.01, p = 0.001). Mutations in KRAS were clonal and concordant with extracranial disease, suggesting that these mutations are likely present within the primary. Our analyses suggest that KRAS mutations could help identify patients with primary melanoma at higher risk of brain metastases who may benefit from more intensive, protracted surveillance.

Update on headache and brain tumors

Headache is one of the leading symptoms often associated with brain tumours. Secondary headaches attributed to intracranial neoplasias have been included in subchapter 7.4 of the third edition of the International Classification of Headache Disorders (ICHD-3). According to ICHD-3, the headache may be attributed to a brain tumour if it has developed in close temporal relation with the development of the neoplasia, has significantly worsened in parallel with the worsening of the tumour, and/or has significantly improved following the successful treatment of the neoplasia. Brain tumour headache was traditionally thought to display some specific clinical characteristics, including worsening in the morning and/or when lying down, being aggravated by Valsalva-like manoeuvres and accompanied by nausea and/or vomiting; however, the studies performed after the advent of modern neurodiagnostic techniques have pointed out that the "classic" brain tumour headache is uncommon, particularly at the time of clinical presentation. Therefore, it becomes critical to seek some specific factors associated with the presence of an intracranial mass (the so-called "red flags") that can guide the physician to establish an accurate diagnosis.

Laser Interstitial Thermal Therapy for Metastatic Melanoma After Failed Radiation Therapy: A Case Series

BACKGROUND

Laser interstitial thermal therapy (LITT) is a growing technology to treat a variety of brain lesions. It offers an alternative to treatment options, such as open craniotomy and stereotactic radiosurgery.

OBJECTIVE

To analyze our experience using LITT for metastatic melanoma.

METHODS

This is a retrospective chart review of the patients from our institution. Our case series involves 5 patients who had previously failed radiation treatment.

RESULTS

Our patients have low complication rates and short hospital stays. Both are considerably lower when compared to the literature for metastatic melanoma.

CONCLUSION

LITT is a safe therapy, with few complications and short hospital stays.

Combination treatments with immunotherapy in brain metastases patients

Immune checkpoint inhibitors (ICI) have revolutionized the treatment of many advanced cancers. However, in most pivotal trials, patients with brain metastases (BM) were either excluded, or only selected patients were allowed. Therefore, there are still some concerns about the safety/efficacy ratio of ICI in patients with BM. In this special report we will provide an overview on the biological rationale for using ICI in the treatment of BM, the reported BM-related outcomes of clinical trials with a focus on ICI plus chemotherapy and ICI plus ICI combinations. Last, we will provide future challenges with this strategy, as well as directions for future research.

Integration of stereotactic radiosurgery or whole brain radiation therapy with immunotherapy for treatment of brain metastases

The prognosis of brain metastases (BM) is traditionally poor. BM are mainly treated by local radiotherapy, including stereotactic radiosurgery (SRS) or whole brain radiation therapy (WBRT). Recently, immunotherapy (i.e., immune checkpoint inhibitors, ICI) has demonstrated a survival advantage in multiple malignancies commonly associated with BM. Individually, radiotherapy and ICI both treat BM efficiently; hence, their combination seems logical. In this review, we summarize the existing preclinical and clinical evidence that supports the applicability of radiotherapy as a sensitizer of ICI for BM. Further, we discuss the optimal timing at which radiotherapy and ICI should be administered and review the safety of the combination therapy. Data from a few clinical studies suggest that combining SRS or WBRT with ICI simultaneously rather than consecutively potentially enhances brain abscopal-like responses and survival. However, there is a lack of conclusion about the definition of "simultaneous"; the cumulative toxic effect of the combined therapies also requires further study. Thus, ongoing and planned prospective trials are needed to further explore and validate the effect, safety, and optimal timing of the combination of immunotherapy with radiotherapy for patients with BM.

Immune Checkpoint Blockade - How Does It Work in Brain Metastases?

Immune checkpoints restrain the immune system following its activation and their inhibition unleashes anti-tumor immune responses. Immune checkpoint inhibitors revolutionized the treatment of several cancer types, including melanoma, and immune checkpoint blockade with anti-PD-1 and anti-CTLA-4 antibodies is becoming a frontline therapy in metastatic melanoma. Notably, up to 60% of metastatic melanoma patients develop metastases in the brain. Brain metastases (BrM) are also very common in patients with lung and breast cancer, and occur in ∼20-40% of patients across different cancer types. Metastases in the brain are associated with poor prognosis due to the lack of efficient therapies. In the past, patients with BrM used to be excluded from immune-based clinical trials due to the assumption that such therapies may not work in the context of "immune-specialized" environment in the brain, or may cause harm. However, recent trials in patients with BrM demonstrated safety and intracranial activity of anti-PD-1 and anti-CTLA-4 therapy. We here discuss how immune checkpoint therapy works in BrM, with focus on T cells and the cross-talk between BrM, the immune system, and tumors growing outside the brain. We discuss major open questions in our understanding of what is required for an effective immune checkpoint inhibitor therapy in BrM.

Microenvironmental Regulation of Tumor Progression and Therapeutic Response in Brain Metastasis

Cellular and non-cellular components of the tumor microenvironment (TME) are emerging as key regulators of primary tumor progression, organ-specific metastasis, and therapeutic response. In the era of TME-targeted- and immunotherapies, cancer-associated inflammation has gained increasing attention. In this regard, the brain represents a unique and highly specialized organ. It has long been regarded as an immunological sanctuary site where the presence of the blood brain barrier (BBB) and blood cerebrospinal fluid barrier (BCB) restricts the entry of immune cells from the periphery. Consequently, tumor cells that metastasize to the brain were thought to be shielded from systemic immune surveillance and destruction. However, the detailed characterization of the immune landscape within border-associated areas of the central nervous system (CNS), such as the meninges and the choroid plexus, as well as the discovery of lymphatics and channels that connect the CNS with the periphery, have recently challenged the dogma of the immune privileged status of the brain. Moreover, the presence of brain metastases (BrM) disrupts the integrity of the BBB and BCB. Indeed, BrM induce the recruitment of different immune cells from the myeloid and lymphoid lineage to the CNS. Blood-borne immune cells together with brain-resident cell-types, such as astrocytes, microglia, and neurons, form a highly complex and dynamic TME that affects tumor cell survival and modulates the mode of immune responses that are elicited by brain metastatic tumor cells. In this review, we will summarize recent findings on heterotypic interactions within the brain metastatic TME and highlight specific functions of brain-resident and recruited cells at different rate-limiting steps of the metastatic cascade. Based on the insight from recent studies, we will discuss new opportunities and challenges for TME-targeted and immunotherapies for BrM.

Clinical experience with combination BRAF/MEK inhibitors for melanoma with brain metastases: a real-life multicenter study

BRAF and MEK kinase inhibitors can be highly effective in treating BRAF-mutant melanomas, but their safety and activity in patients with active/symptomatic brain metastases are unclear. We sought to shed light on this open clinical question. We conducted a multicenter retrospective study on real-life patients with melanoma and active brain metastases treated with combination BRAF/MEK inhibitors. A total of 65 patients were included (38 men and 27 women; median age: 49 years). Of them, 53 patients received dabrafenib/trametinib, 10 received vemurafenib/cobimetinib, one received encorafenib/binimetinib, and one received vemurafenib/trametinib. We did not observe any unexpected treatment-related safety signals in our cohort. Overall, 17 patients continued on therapy through the cutoff date. After initiation of therapy, steroid dose could be decreased in 22 of 33 patients (11 tapered off entirely), anticonvulsants were stopped in four of 21, and narcotics were stopped in four of 12. Median progression-free survival from the start of therapy was 5.3 months (95% confidence interval: 3.6-6.1), and median overall survival was 9.5 months (95% confidence interval: 7.7-13.5). A total of 20 patients were surviving at the cutoff date. Univariate analysis of age, sex, ulceration status, thickness, stage, location, or lactate dehydrogenase did not reveal significant predictors of progression-free survival or overall survival within our cohort, but multivariate analysis suggested that older age, lower risk location of original lesion, and nodular melanoma are poor prognostic indicators. Combination therapy with BRAF/MEK inhibitors is a viable treatment option for patients with BRAF-mutant melanoma and brain metastases, but further studies should help to define the optimal treatment approach in this population.

Stereotactic radiosurgery combined with nivolumab or Ipilimumab for patients with melanoma brain metastases: evaluation of brain control and toxicity

Purpose

To investigate the efficacy and safety of concurrent stereotactic radiosurgery (SRS) and ipilimumab or nivolumab in patients with untreated melanoma brain metastases.

Patients and Methods

Eighty consecutive patients with 326 melanoma brain metastases receiving SRS in combination with ipilimumab or nivolumab were identified from an institutional database and retrospectively evaluated. Patients started systemic treatment with intravenous nivolumab or ipilimumab within one week of receiving SRS. Nivolumab was given at doses of 3 mg/kg every two weeks. Ipilimumab was administered up to four doses of 10 mg/kg, one every 3 weeks, then patients had a maintenance dose of 10 mg/kg every 12 weeks, until disease progression or inacceptable toxicity. Primary endpoint of the study was intracranial progression-free survival (PFS). Secondary endpoints were extracranial PFS, overall survival (OS), and neurological toxicity.

Results

Eighty patients were analyzed. Forty-five patients received SRS and ipilimumab, and 35 patients received SRS and nivolumab. With a median follow-up of 15 months, the 6-month and 12-month intracranial PFS rates were 69% (95%CI,54–87%) and 42% (95%CI,24–65%) for patients receiving SRS and nivolumab and 48% (95%CI,34–64%) and 17% (95%CI,5–31%) for those treated with SRS and ipilimumab (p = 0.02), respectively. Extracranial PFS and OS were 37 and 78% in SRS and nivolumab group, respectively, and 17 and 68% in SRS and ipilimumab group, respectively, at 12 months. Sub-group analysis showed significantly better intracranial PFS for patients receiving multi-fraction SRS (3 × 9 Gy) compared to single-fraction SRS (70% versus 46% at 6 months, p = 0.01), especially in combination with nivolumab. Grade 3 treatment-related adverse events occurred in 11 (24%) patients treated with SRS and ipilimumab and 6 (17%) patients who received SRS and nivolumab. Radiation-induced brain necrosis (RN) occurred in 15% of patients.

Conclusions

Concurrent SRS and ipilimumab or nivolumab show meaningful intracranial activity in patients with either asymptomatic and symptomatic melanoma brain metastases, although a subset of patients may develop symptomatic RN. The combination of nivolumab with SRS is associated with better intracranial control.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0588-y) contains supplementary material, which is available to authorized users.

Susceptibility-weighted imaging in malignant melanoma brain metastasis

BACKGROUND

The value of cerebral susceptibility-weighted imaging (SWI) in malignant melanoma (MM) patients remains controversial and the effect of melanin on SWI is not well understood.

PURPOSE

To systematically analyze the spectrum of intracerebral findings in MM brain metastases (BM) on SWI and to determine the diagnostic value of SWI.

STUDY TYPE

Retrospective.

POPULATION/SUBJECTS

In all, 100 patients with melanoma BM (69 having received radiotherapy [RT] and 31 RT-naïve) and a control group of 100 melanoma patients without BM were included. For detailed analysis of signal characteristics, 175 metastases were studied.

FIELD STRENGTH/SEQUENCE

Gradient echo SWI sequence at 1.5, 3.0, and 9.4 T.

ASSESSMENT

Signal characteristics from melanotic and amelanotic BMs on SWI with a focus on blooming artifacts were analyzed, as well as the presence and longitudinal dynamics of isolated SWI blooming artifacts in patients with and without BM.

STATISTICAL TESTS

Chi-squared and Student's t-test were used for contingency table measures and group data of signal and clinical characteristics, respectively.

RESULTS

Melanotic and amelanotic metastases did not show significant differences of SWI blooming artifacts (38% vs. 43%, P = 0.61). Most metastases without an initial SWI artifact developed a signal dropout during follow-up (80%; 65/81). Isolated SWI artifacts were detected more frequently in patients with BM (20 vs. 9, P = 0.03), of which the majority were found in patients who had received RT (17 vs. 3, P = 0.08). None of these isolated SWI blooming artifacts turned into overt metastases over time (median follow-up: 8.5 months). Similar findings persisted as remnants of successfully treated metastases (88%; 7/8).

DATA CONCLUSION

We conclude that SWI provides little additional diagnostic benefit over standard T₁ -weighted imaging, as melanin content alone does not cause diagnostically relevant SWI blooming. Signal transition of SWI may rather indicate secondary phenomena like microbleeding and/or metal scavenging. Our results suggest that isolated SWI artifacts do not constitute vital tumor tissue but represent unspecific microbleedings, RT-related parenchymal changes or posttherapeutic remnants of former metastatic lesions.

LEVEL OF EVIDENCE

3 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2019;50:1251-1259.

Monitoring Melanoma Using Circulating Free DNA

Genetic material derived from tumours is constantly shed into the circulation of cancer patients both in the form of circulating free nucleic acids and within circulating cells or extracellular vesicles. Monitoring cancer-specific genomic alterations, particularly mutant allele frequencies, in circulating nucleic acids allows for a non-invasive liquid biopsy for detecting residual disease and response to therapy. The advent of molecular targeted treatments and immunotherapies with increasing effectiveness requires corresponding effective molecular biology methods for the detection of biomarkers such as circulating nucleic acid to monitor and ultimately personalise therapy. The use of polymerase chain reaction (PCR)-based methods, such as droplet digital PCR, allows for a very sensitive analysis of circulating tumour DNA, but typically only a limited number of gene mutations can be detected in parallel. In contrast, next-generation sequencing allows for parallel analysis of multiple mutations in many genes. The development of targeted next-generation sequencing cancer gene panels optimised for the detection of circulating free DNA now provides both the flexibility of multiple mutation analysis coupled with a sensitivity that approaches or even matches droplet digital PCR. In this review, we discuss the advantages and disadvantages of these current molecular technologies in conjunction with how this field is evolving in the context of melanoma diagnosis, prognosis, and monitoring of response to therapy.

A Blazing Landscape: Neuroinflammation Shapes Brain Metastasis

Brain metastases are more common than primary CNS tumors and confer grave prognosis on patients, as existing treatments have very limited efficacy. The tumor microenvironment has a central role in facilitating tumorigenesis and metastasis. In recent years, there has been much progress in our understanding of the functional role of the brain metastatic microenvironment. In this review, we discuss the latest advances in brain metastasis research, with special emphasis on the role of the brain microenvironment and neuroinflammation, integrating insights from comparable findings in neuropathologies and primary CNS tumors. In addition, we overview findings on the formation of a hospitable metastatic niche and point out the major gaps in knowledge toward developing new therapeutics that will cotarget the stromal compartment in an effort to improve the treatment and prevention of brain metastases.

Long-term characterization of activated microglia/macrophages facilitating the development of experimental brain metastasis through intravital microscopic imaging

Background

Microglia/macrophages (M/Ms) with multiple functions derived from distinct activation states are key surveillants maintaining brain homeostasis. However, their activation status and role during the brain metastasis of malignant tumors have been poorly characterized.

Methods

Heterozygous CX3CR1-GFP transgenic mice were used to visualize the dynamic changes of M/Ms during the development of experimental brain metastasis through long-term intravital imaging equipped with redesigned bilateral cranial windows. The occurrence of experimental brain metastasis was evaluated after M/Ms were depleted with PLX3397, a CSF-1R inhibitor. The possible mediators of M/Ms in facilitating the brain metastasis were determined using reverse transcription-PCR, immunofluorescence, correlational analysis, and MMP inhibition.

Results

Here, we showed that M/Ms were persistently activated and facilitated the formation of melanoma brain metastasis in vivo. We observed that M/Ms gradually and massively accumulated in the metastasis, with a 2.89-fold increase. To precisely depict the dynamic changes in the activation state of M/Ms, we defined the branching parameter to quantify their morphological alterations. The quantitative data showed that the extent of activation of M/Ms in metastatic foci was enhanced, with a 2.27-fold increase from day 1 to day 21. Along with the activation, the M/Ms increased their moving velocity (4.15-fold) and established a rapid, confined, and discontinuous motility behavior. The occurrence of melanoma brain metastasis was significantly hindered under M/M elimination, indicating the key role of M/Ms in the experimental brain metastasis. Interestingly, we found that M/Ms highly expressed matrix metalloproteinase 3 (MMP3), which were strongly correlated with M/M activation and the decrease of tight junction protein zonula occludens-1 (ZO-1). An MMP inhibitor moderately decreased the occurrence of melanoma brain metastasis, suggesting that MMP3 secreted by M/Ms may facilitate melanoma cell growth.

Conclusions

Our results indicated that the activated M/Ms were essential in the development of melanoma brain metastasis, suggesting that M/Ms are a potential therapeutic target for tumor brain metastasis.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1389-9) contains supplementary material, which is available to authorized users.

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.

Brain Metastases

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

Anti-PD-1/anti-CTLA-4 efficacy in melanoma brain metastases depends on extracranial disease and augmentation of CD8+ T cell trafficking

Inhibition of immune checkpoints programmed death 1 (PD-1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4) on T cells results in durable antitumor activity in melanoma patients. Despite high frequency of melanoma brain metastases (BrM) and associated poor prognosis, the activity and mechanisms of immune checkpoint inhibitors (ICI) in metastatic tumors that develop within the "immune specialized" brain microenvironment, remain elusive. We established a melanoma tumor transplantation model with intracranial plus extracranial (subcutaneous) tumor, mimicking the clinically observed coexistence of metastases inside and outside the brain. Strikingly, intracranial ICI efficacy was observed only when extracranial tumor was present. Extracranial tumor was also required for ICI-induced increase in CD8+ T cells, macrophages, and microglia in brain tumors, and for up-regulation of immune-regulatory genes. Combined PD-1/CTLA-4 blockade had a superior intracranial efficacy over the two monotherapies. Cell depletion studies revealed that NK cells and CD8+ T cells were required for intracranial anti-PD-1/anti-CTLA-4 efficacy. Rather than enhancing CD8+ T cell activation and expansion within intracranial tumors, PD-1/CTLA-4 blockade dramatically (∼14-fold) increased the trafficking of CD8+ T cells to the brain. This was mainly through the peripheral expansion of homing-competent effector CD8+ T cells and potentially further enhanced through up-regulation of T cell entry receptors intercellular adhesion molecule 1 and vascular adhesion molecule 1 on tumor vasculature. Our study indicates that extracranial activation/release of CD8+ T cells from PD-1/CTLA-4 inhibition and potentiation of their recruitment to the brain are paramount to the intracranial anti-PD-1/anti-CTLA-4 activity, suggesting augmentation of these processes as an immune therapy-enhancing strategy in metastatic brain cancer.

Four-year Survival (and Counting) after Stereotactic Radiosurgery to Nearly 100 Brain Metastases: A Case Report

Brain metastases are a relatively common consequence of Stage IV melanoma. Historically, patients with brain metastases fare poorly, with median survival of only weeks to months. Patients with multiple metastases in the brain have often been overlooked in the literature, with the focus being placed more on patients with only a small number of metastases. The authors present a case of a 42-year-old man with a total of 98 brain metastases treated over several Gamma Knife sessions. He is nearly five years out from his initial treatment. This case highlights the fact that there is a large amount of variability in survival after diagnosis with brain metastases. Selection for treatment should be based on the clinical picture and clinicians should take care to avoid selection bias in this population.

The biology and therapeutic management of melanoma brain metastases

The recent years have seen significant progress in the development of systemic therapies to treat patients with advanced melanoma. Use of these new treatment modalities, which include immune checkpoint inhibitors and small molecule BRAF inhibitors, lead to increased overall survival and better outcomes. Although revolutionary, these therapies are often less effective against melanoma brain metastases, and frequently the CNS is the major site of treatment failure. The development of brain metastases remains a serious complication of advanced melanoma that is associated with significant morbidity and mortality. New approaches to both prevent the development of brain metastases and treat established disease are urgently needed. In this review we will outline the mechanisms underlying the development of melanoma brain metastases and will discuss how new insights into metastasis biology are driving the development of new therapeutic strategies. Finally, we will describe the latest data from the ongoing clinical trials for patients with melanoma brain metastases.

In response to Fogarty et al. and why adjuvant whole brain radiotherapy is not recommended routinely

The routine use of adjuvant whole brain radiotherapy (AWBRT) after surgery or stereotactic radiosurgery is now discouraged by a number of international expert panels. Three decades of randomised studies have shown that, although AWBRT improves radiological measures of intracranial disease control, the clinical benefit is unclear and it is also associated with inferior quality of life and neurocognitive function. The number of patients with melanoma in these trials was low, but data suggesting that treatment-related side effects should vary according to histology of the primary malignancy are lacking. For metastatic melanoma, the role of AWBRT to control microscopic disease in the brain is also a less relevant concern because systemic therapies with intracranial activity are now available. Whether AWBRT is useful in select patients deemed at high risk of neurologic death remains undefined.

Intratumoral CD40 activation and checkpoint blockade induces T cell-mediated eradication of melanoma in the brain

CD40 agonists bind the CD40 molecule on antigen-presenting cells and activate them to prime tumor-specific CD8⁺ T cell responses. Here, we study the antitumor activity and mechanism of action of a nonreplicating adenovirus encoding a chimeric, membrane-bound CD40 ligand (ISF35). Intratumoral administration of ISF35 in subcutaneous B16 melanomas generates tumor-specific, CD8⁺ T cells that express PD-1 and suppress tumor growth. Combination therapy of ISF35 with systemic anti-PD-1 generates greater antitumor activity than each respective monotherapy. Triple combination of ISF35, anti-PD-1, and anti-CTLA-4 results in complete eradication of injected and noninjected subcutaneous tumors, as well as melanoma tumors in the brain. Therapeutic efficacy is associated with increases in the systemic level of tumor-specific CD8⁺ T cells, and an increased ratio of intratumoral CD8⁺ T cells to CD4⁺ Tregs. These results provide a proof of concept of systemic antitumor activity after intratumoral CD40 triggering with ISF35 in combination with checkpoint blockade for multifocal cancer, including the brain.

Treatment options for metastatic melanoma are limited. Here the authors show that combining an immunostimulant adenovirus, currently in clinical trials for leukemia, with immune checkpoints blockade (ICB) results in systemic eradication of ICB resistant melanoma tumours from both skin and brain of mice.

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.

Stereotactic radiosurgery of early melanoma brain metastases after initiation of anti-CTLA-4 treatment is associated with improved intracranial control

BACKGROUND

Numerous studies suggest that radiation can boost antitumor immune response by stimulating release of tumor-specific antigens. However, the optimal timing between radiotherapy and immune checkpoint blockade to achieve potentially synergistic benefits is unclear.

MATERIAL AND METHODS

Multi-institutional retrospective analysis was conducted of ninety-nine metastatic melanoma patients from 2007 to 2014 treated with ipilimumab who later received stereotactic radiosurgery (SRS) for new brain metastases that developed after starting immunotherapy. All patients had complete blood count acquired before SRS. Primary outcomes were intracranial disease control and overall survival (OS).

RESULTS

The median follow-up time was 15.5months. In the MD Anderson cohort, patients who received SRS after 5.5months (n=20) of their last dose of ipilimumab had significantly worse intracranial control than patients who received SRS within 5.5months (n=51) (median 3.63 vs. 8.09months; hazard ratio [HR] 2.07, 95% confidence interval [CI] 1.03-4.16, p=0.041). OS was not different between the two arms. The improvement in intracranial control was confirmed in an independent validation cohort of 28 patients treated at Yale-New Haven Hospital. Circulating absolute lymphocyte count before SRS predicted for treatment response as those with baseline counts >1000/µL had reduced risk of intracranial recurrence compared with those with ≤1000/µL (HR 0.46, 95% CI 0.0.23-0.94, p=0.03).

CONCLUSIONS

In this multi-institutional study, patients who received SRS for new brain metastases within 5.5months after ipilimumab therapy had better intracranial disease control than those who received SRS later. Moreover, higher circulating lymphocyte count was associated with improved intracranial disease control.

Role of extra cranial stereotactic body radiation therapy in the management of Stage IV melanoma

OBJECTIVE

To investigate the role of extracranial stereotactic body radiation therapy (SBRT) in the management of oligometastatic melanoma.

METHODS

Patients affected by Stage IV melanoma, with less than three extracranial metastatic lesions, who received SBRT were included in this analysis. Acute and late toxicity, local control (LC), overall survival (OS) and progression-free survival (PFS) were analysed.

RESULTS

31 patients were included in the study. 16 patients (51.6%) were treated for lung meta-stases, 8 patients for liver metastases (25.8%) and 7 (22.6%) for nodal metastases. 38 lesions were irradiated. With a median follow-up time of 13 months, 11 patients (35.4%) were still alive, in four cases (12.9%) with no evidence of disease. Median OS was 10.6 months, and OS at 6, 12 and 24 months was 77, 41 and 21% respectively. LC at 12 and 24 months was 96.6 and 82.8%. 23 patients (74.2%) developed distant metastases. Median PFS was 5.8 months, and PFS at 6, 12 and 24 months was 48.2, 18.5 and 13.9% respectively. Number of irradiated lesions showed a statistically significant correlation only with LC (p = 0.03). Response of the irradiated lesion was related to OS (p = 0.019). Local response showed also a borderline correlation with PFS (p = 0.07).

CONCLUSION

SBRT for extracranial metastases from melanoma is feasible and well tolerated. Response of the irradiated lesions is predictive of OS. Advances in knowledge: SBRT for melanoma extracranial metastases is feasible and the response of the irradiated lesions is predictive of OS.

The Treatment of Melanoma Brain Metastases

Melanoma is the malignancy with the highest rate of dissemination to the central nervous system once it metastasizes. Until recently, the prognosis of patients with melanoma brain metastases (MBM) was poor. In recent years, however, the prognosis has improved due to high-resolution imaging that facilitates early detection of small asymptomatic brain metastases and early intervention with local modalities such as stereotactic radiosurgery. More recently, a number of systemic therapies have been approved by the Food and Drug Administration for metastatic melanoma, resulting in improved survival for many MBM patients. Registration trials for these newer therapies excluded patients with untreated brain metastases, and a number of studies specifically tailored to this population of patients have been conducted or are underway. Herein, we review contemporary locoregional and systemic therapies and describe the unique challenges posed by treatment of brain metastases, such as radionecrosis, cerebral edema, and pseudoprogression. Since the number of systemic and combined modality clinical trials has increased, we expect that the treatment landscape for patients with melanoma brain metastasis will change dramatically. In addition to ongoing clinical trials, which show great promise, we conclude that our understanding of intracranial metastasis remains quite limited. In addition to inter-disciplinary, multi-modality studies, bench-side work to better understand the process of cerebrotropism is needed to fuel more drug development and further improve outcomes.

Treatment of brain metastasis: current status and future directions

PURPOSE OF REVIEW

The purpose of this review is to highlight the most recent advances in the management of brain metastases.

RECENT FINDINGS

Role of local therapies (surgery and stereotactic radiosurgery), new approaches to minimize cognitive sequelae following whole-brain radiotherapy and advances in targeted therapies have been reviewed.

SUMMARY

The implications for clinical trials and daily practice of the increasing use of stereotactic radiosurgery in multiple brain metastases and upfront targeted agents in asymptomatic brain metastases are discussed.

Brain metastases from hepatocellular carcinoma: recent advances and future avenues

The incidence of brain metastases from hepatocellular carcinoma (BMHCC) is becoming more frequent than that of the past as a result of prolonged survival of patients with HCC. Compared with brain metastases from other types of cancer, BMHCC tends to exhibit a high incidence of intracerebral hemorrhage (ICH) and poor liver function. Unfortunately, the prognosis is extremely poor for patients with BMHCC owing to the limited treatment selection. Currently, optimal treatment requires multidisciplinary approaches including surgery, whole-brain radiation therapy and stereotactic radiosurgery. Besides these traditional approaches, novel treatments such as target therapy and immunotherapy provide an opportunity to improve the survival of these patients. This review provides an overview of the incidence, characteristics, prognosis, and current and potential future management strategies for BMHCC.

Targeted Therapies for Melanoma Brain Metastases

Brain metastases are a major clinical challenge occurring in up to 60% of patients suffering from metastatic melanoma. They cause significant clinical symptoms and impair the overall survival prognosis. The introduction of targeted therapies including BRAF and MEK inhibitors as well as CTLA-4 and PD-1 axis targeting immune checkpoint inhibitors have dramatically improved the treatment and prognosis of patients with extracranial metastatic melanoma. Although, similar response rates for extra- and intracranial metastases have been reported, only few data from brain metastasis specific trails are available so far. The following review will provide an overview on the currently available data on targeted therapies, remaining questions and the most important side effects in the special clinical situation of melanoma brain metastases.

Smac mimetics synergize with immune checkpoint inhibitors to promote tumour immunity against glioblastoma

Small-molecule inhibitor of apoptosis (IAP) antagonists, called Smac mimetic compounds (SMCs), sensitize tumours to TNF-α-induced killing while simultaneously blocking TNF-α growth-promoting activities. SMCs also regulate several immunomodulatory properties within immune cells. We report that SMCs synergize with innate immune stimulants and immune checkpoint inhibitor biologics to produce durable cures in mouse models of glioblastoma in which single agent therapy is ineffective. The complementation of activities between these classes of therapeutics is dependent on cytotoxic T-cell activity and is associated with a reduction in immunosuppressive T-cells. Notably, the synergistic effect is dependent on type I IFN and TNF-α signalling. Furthermore, our results implicate an important role for TNF-α-producing cytotoxic T-cells in mediating the anti-cancer effects of immune checkpoint inhibitors when combined with SMCs. Overall, this combinatorial approach could be highly effective in clinical application as it allows for cooperative and complimentary mechanisms in the immune cell-mediated death of cancer cells.

Smac mimetics sensitize cancer cells to the extrinsic cell death pathway and stimulate anti-tumour immunity. In this study, the authors show that Smac mimetics can synergize with immune checkpoint inhibitors to control tumour growth in mouse cancer models, including aggressive CNS tumours, in a cytotoxic CD8⁺ T-cell- and TNFα-dependent manner.

Stereotactic Radiosurgery for Melanoma Brain Metastases: A Comprehensive Clinical Case Series

BACKGROUND

Melanoma has high propensity to metastasize to the brain. With recent gains in improving patient survival, stereotactic radiosurgery (SRS) may offer an effective and less neurotoxic alternative to whole-brain radiation. In the study, we report on the safety and efficacy of SRS in treating melanoma brain metastases in 87 patients.

METHODS

This retrospective multicenter study examined 87 patients with 309 metastases who underwent single-dose or multifractionated SRS for treatment of intracranial metastases from malignant melanoma.

RESULTS

A total of 87 patients with a median age of 62 years (26-85) were treated from 2007-2014. Eighty patients (92%) also had extracranial metastases at time of treatment, and 69 patients (79%) had uncontrolled systemic disease. Seventy-nine patients (91%) underwent single-dose fractions, 7 (8%) underwent 3 fractions, and 1 (1%) was treated in 5 fractions. The mean tumor volume (GTV) treated was 1.92 cc. Five patients developed symptoms of acute phase toxicity, and 4 developed late phase toxicity. None had radionecrosis. The median survival was 6 months. The Kaplan-Meier 1-year survival rate was 31%, and the 1-year local control rate was 91%. The 1-year survival rate for BRAF-positive patients was 42%, and for BRAF-negative patients it was 27%. Forty-two patients (48%) had distant intracranial recurrences, and 1-year distant control rate was 32%.

CONCLUSIONS

SRS is a safe and effective treatment option for intracranial metastases from malignant melanoma. This paper serves as a reference for what is achievable in the absence of highly effective systemic therapy.

Immunotherapy of Malignant Tumors in the Brain: How Different from Other Sites?

Immunotherapy is now advancing at remarkable pace for tumors located in various tissues, including the brain. Strategies launched decades ago, such as tumor antigen-specific therapeutic vaccines and adoptive transfer of tumor-infiltrating lymphocytes are being complemented by molecular engineering approaches allowing the development of tumor-specific TCR transgenic and chimeric antigen receptor T cells. In addition, the spectacular results obtained in the last years with immune checkpoint inhibitors are transfiguring immunotherapy, these agents being used both as single molecules, but also in combination with other immunotherapeutic modalities. Implementation of these various strategies is ongoing for more and more malignancies, including tumors located in the brain, raising the question of the immunological particularities of this site. This may necessitate cautious selection of tumor antigens, minimizing the immunosuppressive environment and promoting efficient T cell trafficking to the tumor. Once these aspects are taken into account, we might efficiently design immunotherapy for patients suffering from tumors located in the brain, with beneficial clinical outcome.

Challenges in the delivery of therapies to melanoma brain metastases

Brain metastases are a major cause of morbidity and mortality in patients with advanced melanoma. Recent approval of several molecularly-targeted agents and biologics has brought hope to patients with this previously untreatable disease. However, patients with symptomatic melanoma brain metastases have often been excluded from pivotal clinical trials. This may be in part attributed to the fact that several of the approved small molecule molecularly-targeted agents are substrates for active efflux at the blood-brain barrier, limiting their effective delivery to brain metastases. We believe that successful treatment of melanoma brain metastases will depend on the ability of these agents to traverse the blood-brain barrier and reach micrometastases that are often not clinically detectable. Moreover, overcoming the emergence of a unique pattern of resistance, possibly through adequate delivery of combination targeted therapies in brain metastases will be important in achieving a durable response. These concepts, and the current challenges in the delivery of new treatments to melanoma brain metastases, are discussed in this review.