Metastatic Melanoma to the Brain: Surgery and Radiation Is Still the Standard of Care

BDE-209 exposure in murine melanoma (B16-F1) cells modulates tumor malignancy and progression in vivo

Melanoma is a type of skin cancer considered aggressive due to its high metastatic ability and rapid progression to other tissues and organs. BDE-209 (2,2',3,3',4,4',5,5',6,6'-decabromodiphenyl ether) is an additive used as a flame retardant and classified as a persistent organic pollutant that has a high bioaccumulation capacity due to its lipophilic nature. This substance has already been detected in rivers, air, soil, plants and even in different human biological samples, such as plasma, umbilical cord blood and breast milk, revealing a great concern to human populations. Thus, in the current study we investigated whether prior exposure of murine melanoma B16-F1 cells to BDE-209 modulates in vivo progression and malignancy of melanoma. B16-F1 cells were cultured and exposed in vitro to BDE-209 (0.01, 0.1 e 1 nM) for 15 days and then inoculated, via caudal vein, in C57BL/6 mice for experimental metastasis analysis after 20 days. Inoculation of BDE-209-exposed cells resulted in 82% increase of metastasis colonized area in the lungs of mice, downregulation of tumor suppressors genes, such as Timp3 and Reck, decrease of lipid peroxidation and increase of systemic and local inflammatory response. These findings are related to melanoma progression. Additionally, the histopathological analysis revealed greater number of focal points of metastases in the lungs and invasiveness of metastases to the mice brain (89%). The results showed that exposure to BDE-209 may alter the phenotype of B16-F1 cells, worsening their metastatic profile. Current data showed that BDE-209 may interfere with the prognosis of melanoma by modulating cells with less invasiveness capacity to a more aggressive profile.

The role of PI3'-lipid signalling in melanoma initiation, progression and maintenance

Phosphatidylinositol-3'-kinases (PI3Ks) are a family of lipid kinases that phosphorylate the 3' hydroxyl (OH) of the inositol ring of phosphatidylinositides (PI). Through their downstream effectors, PI3K generated lipids (PI3K-lipids hereafter) such as PI(3,4,5)P3 and PI(3,4)P2 regulate myriad biochemical and biological processes in both normal and cancer cells including responses to growth hormones and cytokines; the cell division cycle; cell death; cellular growth; angiogenesis; membrane dynamics; and autophagy and many aspects of cellular metabolism. Engagement of receptor tyrosine kinase by their cognate ligands leads to activation of members of the Class I family of PI3'-kinases (PI3Kα, β, δ & γ) leading to accumulation of PI3K-lipids. Importantly, PI3K-lipid accumulation is antagonized by the hydrolytic action of a number of PI3K-lipid phosphatases, most notably the melanoma suppressor PTEN (lipid phosphatase and tensin homologue). Downstream of PI3K-lipid production, the protein kinases AKT1-3 are believed to be key effectors of PI3'-kinase signalling in cells. Indeed, in preclinical models, activation of the PI3K→AKT signalling axis cooperates with alterations such as expression of the BRAFV600E oncoprotein kinase to promote melanoma progression and metastasis. In this review, we describe the different classes of PI3K-lipid effectors, and how they may promote melanomagenesis, influence the tumour microenvironment, melanoma maintenance and progression to metastatic disease. We also provide an update on both FDA-approved or experimental inhibitors of the PI3K→AKT pathway that are currently being evaluated for the treatment of melanoma either in preclinical models or in clinical trials.

Identification of genes and pathways leading to metastasis and poor prognosis in melanoma

Melanoma causes the highest mortality rate among all skin cancers. However, the underlying molecular mechanisms leading to metastasis and poor prognosis in melanoma have not been fully elucidated. In this study, the differentially expressed genes (DEGs) related to metastasis in melanoma were screened out. The results of gene annotation was combined with The Cancer Genome Atlas (TCGA) database. The microRNA (miRNA) network that regulates key genes and their correlation with BRAF^V600E was preliminarily analyzed. Cell and molecular biology experiments were conducted to verify the results of bioinformatics analysis. Results showed that the PI3K-Akt signaling pathway contained the key genes CDK2, CDK4, KIT, and Von Willebrand factor. Survival analysis showed that high expression of the four key genes significantly reduced the survival rate of patients with melanoma. Correlation analysis showed that BRAF^V600E may regulate the expression of the four key genes, and a total of 240 miRNAs may regulate this expression. Experiments showed that the inactivation of key genes inhibits the proliferation, migration, and invasion of melanoma. In conclusion, the PI3K-Akt signaling pathway and the four key genes promoted the proliferation, migration, and invasion of melanoma, and related to poor prognosis of patients with melanoma.

Pharmacological inhibition of USP7 suppresses growth and metastasis of melanoma cells in vitro and in vivo

Melanoma is a highly aggressive type of skin cancer. The development of diverse resistance mechanisms and severe adverse effects significantly limit the efficiency of current therapeutic approaches. Identification of the new therapeutic targets involved in the pathogenesis will benefit the development of novel therapeutic strategies. The deubiquitinase ubiquitin–specific protease‐7, a potential target for cancer treatment, is deregulated in types of cancer, but its role in melanoma is still unclear. We investigated the role and the inhibitor P22077 of ubiquitin‐specific protease‐7 in melanoma treatment. We found that ubiquitin‐specific protease‐7 was overexpressed and correlated with poor prognosis in melanoma. Further, pharmacological inhibition of ubiquitin‐specific protease‐7 by P22077 can effectively inhibit proliferation, and induce cell cycle arrest and apoptosis via ROS accumulation–induced DNA damage in melanoma cells. Inhibition of ubiquitin‐specific protease‐7 by P22077 also inhibits melanoma tumour growth in vivo. Moreover, inhibition of ubiquitin‐specific protease‐7 prevented migration and invasion of melanoma cells in vitro and in vivo by decreasing the Wnt/β‐catenin signalling pathway. Taken together, our study revealed that ubiquitin‐specific protease‐7 acted as an oncogene involved in melanoma cell proliferation and metastasis. Therefore, ubiquitin‐specific protease‐7 may serve as potential candidates for the treatment of melanoma.

Ubiquitination of P53 by E3 ligase MKRN2 promotes melanoma cell proliferation

Melanoma is the most aggressive and lethal type of skin cancer. The aim of the present study was to illustrate the molecular mechanism of makorin ring finger protein 2 (MKRN2) control of melanoma cell proliferation. The expression level of MKRN2 was detected in human malignant melanoma cell lines by immunoblotting and reverse transcription-quantitative PCR. Short hairpin RNAs for MKRN2 were designed and transfected into melanoma cells, and the proliferation of these cells was detected by MTT and colony formation assays. The interaction of MKRN2 with P53 was detected by co-immunoprecipitation and glutathione S-transferase pulldown assays. The ubiquitination of P53 by MKRN2 was detected by in vitro ubiquitination assays. A P53-knockout cell line was generated using the CRISPR-Cas9 method. MKRN2 exhibited higher expression levels in melanoma cells, and downregulation of MKRN2 inhibited melanoma cell growth in a P53-dependent manner. MKRN2 regulated melanoma cell proliferation by interacting and ubiquitylating P53, which suggests that MKRN2 may be a potential therapeutic target for melanoma.

Neutrophil to lymphocyte ratio is an independent predictor of outcome for patients undergoing definitive resection for stage IV melanoma

BACKGROUND AND OBJECTIVES

The aim of this study was to perform a retrospective analysis of survival rates and determine prognostic indicators for patients who underwent definitive surgical resection of stage IV melanoma.

METHODS

Patients included were those who underwent complete resection of metastatic melanoma. Data was analyzed using IBM SPSS 2.0. Survival estimates were derived from Kaplan-Meier, log-rank, and Breslow tests.

RESULTS

The study population (n = 95) consisted of 60 males and 35 females. Median overall survival (OS) from the first metastasectomy was 49 months (95% confidence interval, 31-67 months). OS at 1, 2, and 5 years was 92%, 87%, and 50% respectively. Predictors of survival included clear surgical margins compared to patients with positive margins (median OS 53 vs 20 months, P = .026). A preoperative neutrophil to lymphocyte ratio less than 5 experienced a median OS of 65 months compared to 15 months ( P = .006; multivariable analysis for OS: hazard ratio 3.590, P = .009).

CONCLUSION

This study's results are consistent with previous findings demonstrating favourable long-term outcomes following selective resection of metastatic melanoma. In addition to achieving clear surgical margins, a low preoperative neutrophil to lymphocyte ratio was associated with improved outcomes. These factors may help identify surgical candidates.

Focal radiation necrosis of the brain in patients with melanoma brain metastases treated with pembrolizumab

Introduction

Up to 60% of patients with metastatic melanoma develop melanoma brain metastasis (MBM) during the course of their disease. Surgery, radiosurgery (SRS), stereotactic radiotherapy (SRT), and whole‐brain radiation therapy (WBRT) or combinations of these are commonly used local treatment modalities. Inhibitory monoclonal antibodies against the CTLA‐4 and PD‐1 immune checkpoint receptors significantly improved the survival of metastatic melanoma patients, including patients with MBM. This prolonged survival, and potentially also the immunostimulatory mechanisms, may expose patients to a higher risk for long‐term complications such as focal postradiation necrosis of the brain (RNB).

Methods

We analyzed the incidence of pseudotumoral RNB in a single institution cohort of 142 melanoma patients that were prospectively followed after starting treatment with pembrolizumab in an expanded access program.

Results

Of the 142 patients, 43 (30.7%) patients had MBM at initiation pembrolizumab. Of these, 31 (72.1%) were treated with SRS, 8 (18.6%) with WBRT while 4 (9.3%) had no prior local therapy. Of patients treated with RT, 28 (71.1%) received RT before the initiation of pembrolizumab. 5 (12.8%) patients developed a new symptomatic pseudotumoral lesion at a median time of 11.15 months (range 8‐46) after the RT. In all patients, the diagnosis of RNB was radiologically confirmed. The RNB was treated with corticosteroids in two patients, bevacizumab in two patients, and surgery in three symptomatic patients. The diagnosis was histologically confirmed in the patients treated with surgery.

Conclusion

Melanoma patients with MBM treated with radiosurgery and showing a beneficial response to pembrolizumab are at risk for late RNB. In case of suspected isolated progression at the site of a previously irradiated MBM, the diagnosis of RNB should be considered.

Adjuvant radiotherapy and outcomes of presumed hemorrhagic melanoma brain metastases without malignant cells

Background

Patients with melanoma can present with a hemorrhagic intracranial lesion. Upon resection, pathology reports may not detect any malignant cells. However, the hemorrhage may obscure their presence and so physicians may still decide whether adjuvant radiotherapy should be applied. Here, we report on the outcomes of a series of patients with melanoma with hemorrhagic brain lesions that returned with no tumor cells.

Methods

All melanoma patients who had craniotomies from 2008 to 2017 at a single institution for hemorrhagic brain lesions were identified through retrospective chart review. Those who had pathology reports with no malignant cells were analyzed. Recurrence at the former site of hemorrhage and resection was the primary outcome.

Results

Ten patients met inclusion criteria, and the median follow-up time was 8.5 (1.8-27.3) months. At the time of craniotomy, the median number of brain lesions was 3 (1-25). Two patients had prior craniotomies, eight had prior radiation, and six had prior immunotherapy to the lesion of interest. After surgery, one patient received stereotactic radiosurgery (SRS) to the resection bed. Only one patient developed subsequent melanoma at the resection site; this patient developed the lesion recurrence once and had not received postoperative SRS.

Conclusion

Although small foci of metastatic disease as a source of bleeding for some patients cannot be excluded, melanoma patients with a suspected hemorrhagic brain metastasis that shows no tumor cells on pathology may benefit from close observation. The local recurrence risk in such cases appears to be low, even without adjuvant radiation.

Metabotropic glutamate receptors in cancer

Metabotropic glutamate receptors (mGluRs) are widely known for their roles in synaptic signaling. However, accumulating evidence suggests roles of mGluRs in human malignancies in addition to synaptic transmission. Somatic cell homeostasis presents intriguing possibilities of mGluRs and glutamate signaling as novel targets for human cancers. More recently, aberrant glutamate signaling has been shown to participate in the transformation and maintenance of various cancer types, including glioma, melanoma skin cancer, breast cancer, and prostate cancer, indicating that genes encoding mGluRs, GRMs, can function as oncogenes. Here, we provide a review on the interactions of mGluRs and their ligand, glutamate, in processes that promote the growth of tumors of neuronal and non-neuronal origins. Further, we discuss the evolution of riluzole, a glutamate release inhibitor approved for amyotrophic lateral sclerosis (ALS), but now fashioned as an mGluR1 inhibitor for melanoma therapy and as a radio-sensitizer for tumors that have metastasized to the brain. With the success of riluzole, it is not far-fetched to believe that other drugs that may act directly or indirectly on other mGluRs can be beneficial for multiple applications. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.

Whole-brain radiotherapy in patients with brain metastases from melanoma

AIMS

To describe results of melanoma brain metastases (BM) treated with whole-brain radiation (WBRT).

METHODS

Retrospective review of patients with melanoma BM treated with WBRT divided into two groups based on the timing of WBRT (at BM diagnosis or recurrence).

RESULTS

We identified 61 patients with melanoma BM who received WBRT. For the group treated at diagnosis (n = 39): median overall survival was 3 months; best radiographic response included one partial response, ten stable disease, 18 progressive disease, and ten no follow-up imaging. For the group treated at recurrence (n = 22): median overall survival was 3 months; best radiographic response was three partial response, four stable disease, eight progressive disease, and seven no follow-up imaging.

CONCLUSION

WBRT activity was limited; however, its role in symptom palliation is unclear.

The current management of brain metastasis in melanoma: a focus on riluzole

Brain metastasis is a common endpoint in human malignant melanoma, and the prognosis for patients remains poor despite advancements in therapy. Current treatment for melanoma metastatic to the brain is grouped into those providing symptomatic relief such as corticosteroids and antiepileptic agents, to those that are disease modifying. Related to the latter group, recent studies have demonstrated that aberrant glutamate signaling plays a role in the transformation and maintenance of various cancer types, including melanoma. Glutamate secretion from these and surrounding cells have been found to stimulate regulatory pathways that control tumor growth, proliferation and survival in vitro and in vivo. The antiglutamatergic actions of an inhibitor of glutamate release, riluzole, have been detected by its ability to clear glutamate from the synapse, and it has been shown to inhibit glutamate release rather than directly inhibiting glutamate receptors. Preclinical studies have demonstrated the ability of riluzole to act as a radiosensitizing agent in melanoma. The effect of riluzole on downstream glutamatergic signaling has pointed to cross talk between the metabotropic G-protein-coupled glutamate receptors implicated in a subset of human melanomas with other signaling pathways, including apoptotic, angiogenic, ROS and cell invasion mechanisms, thus establishing its potential to be further explored in combination therapy regimens for both primary human melanoma and melanoma metastatic to the brain.

[Primary malignant melanoma of the central nervous system: A diagnostic challenge]

BACKGROUND

The rare incidence of primary malignant melanoma of the central nervous system and its ability to mimic other melanocytic tumors on images makes it a diagnostic challenge for the neurosurgeon.

CLINICAL CASE

A 51-year-old patient, with a tumor located in the right forniceal callosum area. Total surgical excision was performed. Histopathological result was consistent with the diagnosis of primary malignant melanoma of the central nervous system, after ruling out extra cranial and extra spinal melanocytic lesions.

CONCLUSIONS

The primary malignant melanoma of the central nervous system is extremely rare. There are features in magnetic resonance imaging that increase the diagnostic suspicion; nevertheless there are other tumors with more prevalence that share some of these features through image. Since there is not an established therapeutic standard its prognosis is discouraging.

First interim analysis of a randomised trial of whole brain radiotherapy in melanoma brain metastases confirms high data quality

Background

Brain metastases are a common cause of death in patients with melanoma. The role of adjuvant whole brain radiotherapy (WBRT) following local treatment of intracranial melanoma metastases is controversial. The Australian and New Zealand Melanoma Trials Group (ANZMTG) and the Trans-Tasman Radiation Oncology Group (TROG) are leading the first ever single histology randomised trial investigating this question. The primary endpoint is distant intracranial failure on magnetic resonance imaging (MRI) within twelve months of randomisation. The first planned interim analysis was performed twelve months after randomisation of the 100^th patient. The analysis was an opportunity to review completeness of the trial data to date.

Methods

All data received up to the end of twelve months after randomisation of the 100th patient was reviewed.

Results

Review of pathology reports confirmed that all 100 patients had stage IV melanoma and were appropriately entered into the study. Of the 47 distant intracranial events, 34 occurred in isolation (i.e. only distant failure was identified), whilst 13 were accompanied by local failure. Data review showed compliance with the protocol mandated MRI schedule and accuracy of intracranial failure reporting was very high. The Quality of Life (QoL) component of the study achieved a 91% completion rate. For the neurocognitive function (NCF) assessments, a high completion rate was maintained throughout the 12 month period. Where assessments were not performed at expected time points, valid reasons were noted. Radiotherapy quality was high. Of 50 patients who received WBRT, 32 were reviewed as per protocol design and there was only one major variation out of 308 data points reviewed (0.3%). There were minimal trial related adverse events (AEs) and no serious adverse events (SAEs). Pre-specified protocol stopping rules were not met.

Conclusions

The Data Safety Monitoring Committee (DSMC) recommended the trial continue recruitment after reviewing the unblinded data. The data provision and quality to date indicates that a reliable outcome will be obtained when the final analysis is performed. Accrual is ongoing with 156 out of 200 patients randomised to date (26^th November 2014).

Accrual to a randomised trial of adjuvant whole brain radiotherapy for treatment of melanoma brain metastases is feasible

Background

Brain metastases (BMs) are common in melanoma patients. Adjuvant whole brain radiotherapy (WBRT) following local treatment of intracranial melanoma metastases with neurosurgery and/or stereotactic radiosurgery is controversial. A randomised trial is needed. However, accrual to WBRT trials has been problematic. A pilot study by Australia and New Zealand Melanoma Trials Group (ANZMTG) was conducted to see if accrual was feasible.

Methods

Sites canvassed for interest included those who treat melanoma patients, had a proven accrual in previous melanoma trials and who had the relevant infrastructure support. Feasibility forecasts from interested sites were sought. These were compared to the patient numbers documented in the research contracts. A target accrual of 60 patients in 2 years was set. Funding was sought for the pilot study. Basic demographics of the pilot study cohort were collected.

Results

The first centre opened December 2008; the first patient was randomised in April 2009. The pilot accruing period concluded in September, 2011. In 30 months, 54 patients from 10 of a total of 17 activated sites in Australia (39, 72%) and in Norway (15, 28%) had been accrued. Feasibility forecasts predicted 133 trial eligible patients per year (including 108 Australian + 25 International patients). Site estimates generally overestimated accrual with 4 of 17 active sites estimating within 50% of target numbers. Sites with patient estimates calculated from records were more accurate than those estimated from memory. The overall recruitment target was lower in the research contracts when compared to the feasibility evaluation. Basic demographics of the pilot study revealed 62% of patients were males; 58% had a single metastasis, 28% had two and 14% had three metastases. 12-month overall survival was 50%.

Conclusions

Despite only 54 patients and not the full 60 patient target being accrued in two years the Trial Management Committee and Data Safely Monitoring Committee approved the continuation of the pilot study to the main trial. On the basis of this successful pilot study, funding was achieved for the full study. 143 patients of a target of 200 have been randomised by June 2014.

Comparative analysis of pathology and boronophenylalanine uptake in experimental orthotopic and heterotopic amelanotic melanoma

Pathobiologic characteristics of cerebral and cutaneous melanoma may cause an increase in mortality resulting from brain metastases in advanced melanoma patients, in addition to anatomic lesions and biological effects caused by the tumor location. We established intracranial and subcutaneous melanoma models using cultured malignant cells derived from amelanotic melanoma. The median survival times in a mouse model with intracranial tumors was 20 days, but a mouse model with subcutaneous tumors did not show cachexia until they were killed 28 days after inoculation with tumor cells. Histopathological analysis showed that a high karyokinesis phase and nuclear pleomorphism appeared in the intracranial model compared with the subcutaneous tumor model mice. The tumor boron concentration at 2.5 h after boronophenylalanine administration was 15.21±3.88 μg/g in an intracranial melanoma xenograft and 19.85±3.63 μg/g in a subcutaneous melanoma xenograft. Intracranial melanoma showed more malignancy and shorter survival time than did subcutaneous melanoma when the same number of tumor cells were injected, and subcutaneous and intracranial amelanotic malignant melanoma tumors are both fitted for boron neutron capture therapy.