Temozolomide and whole brain irradiation in melanoma metastatic to the brain: a phase II trial of the Cytokine Working Group

Management of Brain Metastases: A Review of Novel Therapies

Brain metastases (BMs) represent the most common intracranial tumors in adults, and most commonly originate from lung, followed by breast, melanoma, kidney, and colorectal cancer. Management of BM is individualized based on the size and number of brain metastases, the extent of extracranial disease, the primary tumor subtype, neurological symptoms, and prior lines of therapy. Until recently, treatment strategies were limited to local therapies, like surgical resection and radiotherapy, the latter in the form of whole-brain radiotherapy or stereotactic radiosurgery. The next generation of local strategies includes laser interstitial thermal therapy, magnetic hyperthermic therapy, post-resection brachytherapy, and focused ultrasound. New targeted therapies and immunotherapies with documented intracranial activity have transformed clinical outcomes. Novel systemic therapies with intracranial utility include new anaplastic lymphoma kinase inhibitors like brigatinib and ensartinib; selective "rearranged during transfection" inhibitors like selpercatinib and pralsetinib; B-raf proto-oncogene inhibitors like encorafenib and vemurafenib; Kirsten rat sarcoma viral oncogene inhibitors like sotorasib and adagrasib; ROS1 gene rearrangement (ROS1) inhibitors, anti-neurotrophic tyrosine receptor kinase agents like larotrectinib and entrectinib; anti-human epidermal growth factor receptor 2/epidermal growth factor receptor exon 20 agent like poziotinib; and antibody-drug conjugates like trastuzumab-emtansine and trastuzumab-deruxtecan. This review highlights the modern multidisciplinary management of BM, emphasizing the integration of systemic and local therapies.

Systemic Therapy for Melanoma Brain and Leptomeningeal Metastases

OPINION STATEMENT

Melanoma has a high propensity to metastasize to the brain which portends a poorer prognosis. With advanced radiation techniques and targeted therapies, outcomes however are improving. Melanoma brain metastases are best managed in a multi-disciplinary approach, including medical oncologists, neuro-oncologists, radiation oncologists, and neurosurgeons. The sequence of therapies is dependent on the number and size of brain metastases, status of systemic disease control, prior therapies, performance status, and neurological symptoms. The goal of treatment is to minimize neurologic morbidity and prolong both progression free and overall survival while maximizing quality of life. Surgery should be considered for solitary metastases, or large and/or symptomatic metastases with edema. Stereotactic radiosurgery offers a benefit over whole-brain radiation attributed to the relative radioresistance of melanoma and reduction in neurotoxicity. Thus far, data supports a more durable response with systemic therapy using combination immunotherapy of ipilimumab and nivolumab, though targeting the presence of BRAF mutations can also be utilized. BRAF inhibitor therapy is often used after immunotherapy failure, unless a more rapid initial response is needed and then can be done prior to initiating immunotherapy. Further trials are needed, particularly for leptomeningeal metastases which currently require the multi-disciplinary approach to determine best treatment plan.

Analysis of Demographics and Outcomes of Surgical Resection in the Central Nervous System of Patients With Metastatic Melanoma

Background

Patients with melanoma frequently develop central nervous system metastases. Oligometastatic disease is often treated either by surgical resection or by stereotactic radiotherapy. This study investigates the trends and clinical outcomes of patients with melanoma who have undergone surgical procedures on the central nervous system during their hospitalization.

Methods

A retrospective study was performed based on admissions of adult patients who underwent craniotomy for metastatic melanoma from 2000 to 2014 using the Nationwide Inpatient Sample database. The primary outcome measure was all-cause in-hospital mortality. Secondary outcomes included hospital length of stay (LOS) and discharge disposition (home/home with health care and skilled nursing facilities/long-term acute care (SNFs/LTAC)). Factors associated with in-hospital mortality were examined by multivariable logistic regression. We adjusted for patient and hospital characteristics, payer, and comorbid conditions. We also examined trends of mortality for the study years.

Results

There were an estimated 1,216 discharges of patients with melanoma undergoing craniotomy during the study period. Patients undergoing surgical interventions were typically males (69%) and whites (79%). Ninety-eight percent of procedures were performed at teaching hospitals. Unadjusted all-cause in-hospital mortality was 3.1%. There was no significant difference in mortality over 13 years. Age, gender, and race were not associated with increased in-hospital mortality. LOS was longer in elderly and those with higher Charlson Comorbidity Index. Of the survivors, 76% were discharged to home or with home healthcare while 24% were discharged to SNFs/LTAC. Patients with age > 65 (odds ratio (OR): 2.9; 95% confidence interval (CI): 2.2 - 3.9, P < 0.001) and those with higher Charlson Comorbidity Index (OR: 1.2; 95% CI: 1.1 - 1.3) had higher odds for being discharged to SNFs/LTAC.

Conclusions

Patients who undergo craniotomy for metastatic melanoma have a low in-hospital mortality rate. One quarter of patients were discharged to SNFs/LTAC.

Long-term Overall Survival and Predictors in Anti-PD-1-naive Melanoma Patients With Brain Metastases Treated With Immune Checkpoint Inhibitors in the Real-world Setting: A Multicohort Study

Long-term survival outcomes among melanoma patients with brain metastases treated with immune checkpoint inhibitors are limited. In this retrospective study at 2 centers, metastatic melanoma patients with radiographic evidence of brain metastases who received anti-programmed death-1 (PD-1) monotherapy or nivolumab in combination with ipilimumab between 2014 and 2017 were included. Overall survival (OS) was assessed in diagnosis-specific graded prognostic assessment (ds-GPA) and melanoma-molecular graded prognostic assessment (molGPA) prognostic risk groups. Baseline clinical covariates were used to identify predictors of OS in univariate/multivariable Cox proportional-hazards models. A total of 84 patients (58 monotherapy, 26 combination) were included with a median duration of follow-up of 43.4 months (maximum: 5.1 y). The median OS [95% confidence interval (CI)] was 3.1 months (1.8, 7) for ds-GPA 0-1, 22.1 months [5.4, not reached (NR)] for ds-GPA 2 and NR (24.9, NR) for ds-GPA 3-4 in the monotherapy cohort [hazard ratio (HR) for ds-GPA 3-4 vs. 0-1: 0.13 (95% CI: 0.052, 0.32); 0.29 (95% CI: 0.12, 0.63) for ds-GPA 2 vs. 0-1]. The median OS was 1.1 months (95% CI: 0.3, NR) for ds-GPA 0-1, 11.8 months (95% CI: 2.9, 23.3) for ds-GPA 2 and 24.4 months (95% CI: 3.4, NR) for ds-GPA 3-4 in the combination cohort [HR for 3-4 vs. 0-1: 0.013 (95% CI: 0.0012, 0.14); HR for ds-GPA 2 vs. 0-1: 0.033 (0.0035, 0.31)]. Predictors associated with longer survival included ds-GPA or molGPA>1 (among prognostic indices), neutrophil-to-lymphocyte ratio (<4 vs. ≥4), while high lactate dehydrogenase, neurological symptoms, and leptomeningeal metastases were associated with shorter survival. Baseline ds-GPA/molGPA>1 and neutrophil-to-lymphocyte ratio <4 were strong predictors of long-term survival to anti-PD-1-based immune checkpoint inhibitors in melanoma brain metastases patients previously naive to anti-PD-1 therapy in a real-world clinical setting treated at independent centers.

Emerging and investigational targeted chemotherapy and immunotherapy agents for metastatic brain tumors

INTRODUCTION

Metastases to the central nervous system are the most common cause of malignant intracranial tumors in adults. Current standard of care includes surgery and radiation, but overall survival remains poor. A range of systemic therapies are emerging as promising treatment options for these patients.

AREAS COVERED

This study reviews novel drug regimens that are under investigation in phase 1 and 2 clinical trials. To identify relevant therapies under clinical investigation, a search was performed on http://clinicaltrials.gov and Pubmed with the keywords brain metastasis, Phase I clinical trial, and Phase II clinical trial from 2016 to 2020. The authors detail the mechanisms of action of all trial agents, outline evidence for their utility, and summarize the current state of the field.

EXPERT OPINION

Current advancements in the medical management of brain metastases can be categorized into targeted therapies, methods of overcoming treatment resistance, novel combinations of therapies, and modulation of the tumor microenvironment with a specific focus on immunotherapy. Each of these realms holds great promise for the field going forward. A more streamlined structure for enrollment into clinical trials will be a crucial step in accelerating progress in this area.

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

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

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

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

Overview of metastatic disease of the central nervous system

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

Management of intracranial melanomas in the era of precision medicine

Melanoma is the most lethal of skin cancers, in part because of its proclivity for rapid and distant metastasis. It is also potentially the most neurotropic cancer in terms of probability of CNS metastasis from the primary lesion. Despite surgical resection and radiotherapy, prognosis remains guarded for patients with brain metastases. Over the past five years, a new domain of personalized therapy has emerged for advanced melanoma patients with the introduction of BRAF and other MAP kinase pathway inhibitors, immunotherapy, and combinatory therapeutic strategies. By targeting critical cellular signaling pathways and unleashing the adaptive immune response against tumor antigens, a subset of melanoma patients have demonstrated remarkable responses to these treatments. Over time, acquired resistance to these modalities inexorably develops, providing new challenges to overcome. We review the rapidly evolving terrain for intracranial melanoma treatment, address likely and potential mechanisms of resistance, as well as evaluate promising future therapeutic approaches currently under clinical investigation.

Primary oral malignant melanoma metastasis to the brain and breast: A case report and literature review

Primary oral malignant melanoma is a rare tumor, which is estimated to comprise 0.2–8.0% of all melanoma cases. This type of cancer is fairly uncommon, its prognosis is dismal, and it frequently exhibits a biologically aggressive behavior. The common location of primary oral malignant melanoma is the hard palate and maxillary alveolus. In ~85% of cases, the melanoma will metastasize to the liver, lung, bone and brain early in the course of the disease. The present study reports the case of a 50-year-old premenopausal woman who presented with primary oral malignant spindle cell melanoma (T3bN2aM0) and underwent complete surgical resection followed by an adjuvant course of radiation therapy. After 1 year, the patient presented with sudden onset slurred speech, and upon examination, was found to have left-sided hemiparesis and a hard left breast mass. Workup confirmed breast and brain metastasis. The patient developed lung metastasis 4 weeks later and was referred for palliative care.

Updates in the management of brain metastases

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

Recursive Partitioning Analysis of Prognostic Factors for Patients with Four or More Intracranial Metastases Treated with Radiosurgery

The purpose of this study was to devise a new recursive partitioning analysis (RPA) of patients with four or more intracranial metastases treated with a single radiosurgery procedure to identify a class of patients with extended survival. 205 patients underwent Gamma Knife radiosurgery for four or more intracranial metastases (median = 5, range 4–18) during one session. The median total treatment volume was 6.8 cc (range 0.6–51.0 cc). Radiosurgery was used as sole management (17% of patients), or in combination with WB-RT (46%), or after failure of WB-RT (38%). The median marginal radiosurgery dose was 16 Gy (range 12–20 Gy). RPA assessed the effects of age, Karnofsky >70, extracranial disease, visceral metastases, number of metastases, total treatment volume, history of breast and melanoma primaries on survival. The median overall survival after radiosurgery for all patients was 8 months. RPA identified a favorable subgroup of 78 patients (43% of the series) with a total treatment volume <7 cc and < 7 brain metastases (Class 1), with a median survival of 13 months. This subgroup's survival was significantly better (p <0.00005) than the remaining patients (Class 2) (n=111) with a median survival of 6 months. In conclusion, RPA of multiple brain metastasis patients identified 2 distinct cohorts of patients. Class 1 patients have a total treatment volume <7 cc and < 7 metastases (4–6) with favorable survival after Radiosurgery and Class 2 patients have a total treatment volume ≥ 7 cc and/or ≥ 7 metastases and have a significantly poorer survival.

Whole Brain Radiotherapy and RRx-001: Two Partial Responses in Radioresistant Melanoma Brain Metastases from a Phase I/II Clinical Trial: A TITE-CRM Phase I/II Clinical Trial

BACKGROUND: Kim et al. report two patients with melanoma metastases to the brain that responded to treatment with RRx-001 and whole brain radiotherapy (WBRT) without neurologic or systemic toxicity in the context of a phase I/II clinical trial. RRx-001 is an reactive oxygen and reactive nitrogen species (ROS/RNS)-dependent systemically nontoxic hypoxic cell radiosensitizer with vascular normalizing properties under investigation in patients with various solid tumors including those with brain metastases. SIGNIFICANCE: Metastatic melanoma to the brain is historically associated with poor outcomes and a median survival of 4 to 5 months. WBRT is a mainstay of treatment for patients with multiple brain metastases, but no significant therapeutic advances for these patients have been described in the literature. To date, candidate radiosensitizing agents have failed to demonstrate a survival benefit in patients with brain metastases, and in particular, no agent has demonstrated improved outcome in patients with metastatic melanoma. Kim et al. report two patients with melanoma metastases to the brain that responded to treatment with novel radiosensitizing agent RRx-001 and WBRT without neurologic or systemic toxicity in the context of a phase I/II clinical trial.

Survival of patients with metastatic melanoma and brain metastases in the era of MAP-kinase inhibitors and immunologic checkpoint blockade antibodies: A systematic review

BACKGROUND

The incidence of brain metastases (BM) in melanoma patients is common and associated with poor prognosis. MAP-kinase inhibitors and immunologic checkpoint blockade antibodies led to improved survival of metastatic melanoma patients; however, patients with BM are under-represented or excluded from the majority of clinical trials and the impact of new drugs on their survival is less clear. With the present systematic review, we aimed to analyze outcomes of patients with melanoma BM treated with the new drugs, both in the setting of phase I-II-III clinical trials and in the "real world".

METHODS

An electronic search was performed to identify studies reporting survival outcomes of patients with melanoma BM treated with MAP-kinase inhibitors and/or immunologic checkpoint blockade antibodies, regardless of study design.

RESULTS

Twenty-two studies were included for a total of 2153 patients. Median OS was 7.9 months in phase I-II-III trials and 7.7 months in "real world" studies. In clinical trials, median OS was 7.0 months for patients treated with immunotherapy and 7.9 months for patients treated with BRAF inhibitors. In "real world" studies, median OS was 4.3 months and 7.7 months for patients treated with immunotherapy and BRAF inhibitors, respectively. Evidence of clinical activity exists for both immunotherapy and MAP-kinase inhibitors.

CONCLUSIONS

MAP-kinase inhibitors and immunologic checkpoint blockade antibodies have clinical activity and may achieve improved OS in patients with metastatic melanoma and BM. These results support the inclusion of patients with BM in investigations of new agents and new treatment regimens for metastatic melanoma.

Chemotherapy for Melanoma. Cancer Treat Res. 2016;167:209-229. [PMID: 26601864 DOI: 10.1007/978-3-319-22539-5_8]

Prior to the recent therapeutic advances, chemotherapy was the mainstay of treatment options for advanced-stage melanoma. A number of studies have investigated various chemotherapy combinations in order to expand on the clinical responses achieved with single-agent dacarbazine, but these have not demonstrated an improvement in overall survival. Similar objective responses were observed with the combination of carboplatin and paclitaxel as were seen with single-agent dacarbazine. The combination of chemotherapy and immunotherapy, known as biochemo-therapy, has shown high clinical responses; however, biochemo-therapy has not been shown to improve overall survival and resulted in increased toxicities. In contrast, palliation and long-term responses have been observed with localized treatment with isolated limb perfusion or infusion in limb-isolated disease. Although new, improved therapeutic options exist for first-line management of advanced-stage melanoma, chemotherapy may still be important in the palliative treatment of refractory, progressive, and relapsed melanoma. We review the various chemotherapy options available for use in the treatment and palliation of advanced-stage melanoma, discuss the important clinical trials supporting the treatment recommendations, and focus on the clinical circumstances in which treatment with chemotherapy is useful.

Treatment of Melanoma CNS Metastases

The discovery of the BRAFV600 mutation and the development of targeted therapies directed against this mutation as well as effective immunotherapies with durable benefits have revolutionized the treatment of patients with melanoma. Nonetheless, the frequent occurrence of brain metastases in patients with advanced melanoma represents a significant obstacle to long-term, high quality survival. The application of stereotactic radiation therapy has provided an opportunity to control brain metastases in the majority of patients with metastatic melanoma reducing the impact of these lesions on morbidity and mortality and enabling patients to receive and potentially benefit from these novel systemic treatments. Encouragingly, several of these novel new therapies have shown antitumor activity against CNS metastases that approach that seen against extracranial disease. As a consequence, several effective treatment options are now available for patients with melanoma brain metastases. With these tools in hand, it is anticipated that further investigation into the optimal sequence and/or combination of systemic therapies and local therapies along with multidisciplinary team practice will continue to improve the outcome of patients with this previously life-limiting disease complication.

Multidisciplinary approach to brain metastasis from melanoma: the emerging role of systemic therapies

Melanoma brain metastases are common, difficult to treat, and carry a poor prognosis. Until recently, systemic therapy was ineffective. Local therapy (including surgery, stereotactic radiotherapy, and whole brain radiotherapy) was considered the only option for a chance of disease control in the brain, and was highly dependent on the patient's performance status and age, number and size of brain metastases, and the presence of extracranial metastases. Since 2010, three drugs have demonstrated activity in progressing or "active" brain metastases including the anti-CTLA4 antibody ipilimumab (phase II study of 72 patients), and the BRAF inhibitors dabrafenib (phase II study of 172 patients, both previously treated and untreated brain metastases) and vemurafenib (a pilot study of 24 patients with heavily pretreated brain metastases). The challenge and unanswered question for clinicians is how to sequence all the available therapies, both local and systemic, to optimize the patient's quality of life and survival. This is an area of intense clinical research. The treatment of patients with melanoma brain metastases should be discussed by a multidisciplinary team of melanoma experts including a neurosurgeon, medical oncologist, and radiation oncologist. Important clinical features that help determine appropriate first line therapy include single compared with solitary brain metastasis, resectablity, BRAF mutation status of melanoma, rate of progression/performance status, and the presence of extracranial disease.

Clinical Management of Multiple Melanoma Brain Metastases: A Systematic Review

IMPORTANCE

The treatment of multiple brain metastases (MBM) from melanoma is controversial and includes surgical resection, stereotactic radiosurgery (SRS), and whole-brain radiation therapy (WBRT). Several new classes of agents have revolutionized the treatment of metastatic melanoma, allowing some subsets of patients to have long-term survival. Given this, management of MBM from melanoma is continually evolving.

OBJECTIVE

To review the current evidence regarding the treatment of MBM from melanoma.

EVIDENCE REVIEW

The PubMed database was searched using combinations of search terms and synonyms for melanoma, brain metastases, radiation, chemotherapy, immunotherapy, and targeted therapy published between January 1, 1995, and January 1, 2015. Articles were selected for inclusion on the basis of targeted keyword searches, manual review of bibliographies, and whether the article was a clinical trial, large observational study, or retrospective study focusing on melanoma brain metastases. Of 2243 articles initially identified, 110 were selected for full review. Of these, the most pertinent 73 articles were included.

FINDINGS

Patients with newly diagnosed MBM can be treated with various modalities, either alone or in combination. Level 1 evidence supports the use of SRS alone, WBRT, and SRS with WBRT. Although the addition of WBRT to SRS improves the overall brain relapse rate, WBRT has no significant impact on overall survival and has detrimental neurocognitive outcomes. Cytotoxic chemotherapy has largely been ineffective; targeted therapies and immunotherapies have been reported to have high response rates and deserve further attention in larger clinical trials. Further studies are needed to fully evaluate the efficacy of these novel regimens in combination with radiation therapy.

CONCLUSIONS AND RELEVANCE

At this time, the standard management for patients with MBM from melanoma includes SRS, WBRT, or a combination of both. Emerging data exist to support the notion that SRS in combination with targeted therapies or immune therapy may obviate the need for WBRT; prospective studies are required to fully evaluate the efficacy of these novel regimens in combination with radiation therapy.

Management of melanoma brain metastases

Relapses in the brain remain a major obstacle to cure in many patients with advanced melanoma. At present, the management of melanoma brain metastases continues to rely heavily on surgical and radiotherapeutic interventions, which have become safer and more effective with modern imaging, surgery and radiation technologies. Additionally, novel targeted and immunotherapeutic agents, shown to generate meaningful intracranial response and survival benefit in patients with melanoma brain metastases when compared with historical controls, expand systemic treatment options for this subset of patients. These systemic therapies become particularly important when intracranial disease burden precludes neuro- or radio-surgery. Considerable multidisciplinary research effort is ongoing to improve outcomes for melanoma patients with brain metastases, a key challenge in the management of advanced melanoma.

Systemic therapy of brain metastases

Brain metastases are a common complication of cancer and continue to be associated with a poor prognosis. Management of brain metastases typically requires a multidisciplinary approach which may include whole-brain radiation therapy, stereotactic radiosurgery, surgery, and systemic therapy. Historically, the use of systemic therapy in brain metastases has been challenging because of the resistance to conventional chemotherapies secondary to the blood-brain barrier and an often heavily pre-treated patient population, and the paucity of well-conducted randomized trials in these heterogeneous patient populations. Newer agents, including immunotherapy and targeted therapies, are playing increasingly important roles in the up-front management of brain metastases. In this overview, we review recent advances in systemic therapies for brain metastases and the evidence supporting their use in this patient population.

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.

Treatment patterns and outcomes in BRAF V600E-mutant melanoma patients with brain metastases receiving vemurafenib in the real-world setting

Brain metastases are a common and serious complication among patients with metastatic melanoma. The selective BRAF inhibitor vemurafenib has demonstrated clinical efficacy in patients with BRAF V600E-mutant melanoma brain metastases (MBM). We examined the real-world application and clinical outcomes of vemurafenib in this patient population. Demographic, treatment patterns, response, and survival data were collected from medical charts. Clinical data on 283 patients with active BRAF V600E-mutant MBM treated with vemurafenib were provided by 70 US oncologists. Mean age was 57.2 years, 60.8% were male, 67.5% had ECOG performance status of 0–1, and 43.1% used corticosteroids at vemurafenib initiation. Median follow-up was 5.7 months. Following vemurafenib initiation, 48.1% of patients experienced intracranial response and 45.6% experienced extracranial response. The Kaplan–Meier estimate for overall survival was 59% at 12 months. Multivariate analyses showed associations between intracranial response and both corticosteroid use and vemurafenib as initial therapy after MBM diagnosis. Larger size (5–10 mm vs. <5 mm) and number of brain metastases (≥5 vs. <2) and progressive extracranial disease at treatment initiation were associated with decreased intracranial response and increased risk of disease progression. Multiple extracranial sites (2 vs. <2) and the absence of local treatments were also associated with increased risk of progression. Increased risk of death was associated with ≥2 extracranial disease sites, progressive extracranial disease, and ≥5 brain metastases. Subgroups of MBM patients may derive more benefit with vemurafenib, warranting prospective investigation.

Comparative effectiveness in melanoma

The worldwide incidence of melanoma continues to rise. It is a leading cause of cancer death and the second leading cause of loss of productive years of life. Although the diagnosis of melanoma is straightforward, there remain many controversies regarding treatment and surveillance. This chapter addresses important questions in melanoma treatment such as sentinel lymph node biopsy, what to do with a positive sentinel lymph node, margins of resection for melanoma, radiation for primary, nodal and metastatic melanoma, and routine use imaging. Through this chapter, the evidence for these controversial subjects and the barriers to resolution will be elucidated.

Controversies in the management of advanced melanoma: "gray" areas amid the "black and blue"

OBJECTIVE

To examine the current controversies and discuss consensus recommendations regarding treatment sequencing and the role of BRAF inhibitor at disease progression.

DATA SOURCE

An English-language literature search of MEDLINE/PubMed (1966-May 2014), using the keywords advanced melanoma, ipilimumab, cytotoxic T-lymphocyte antigen 4, dabrafenib, vemurafenib, BRAF inhibitor, trametinib, MEK inhibitor, and treatment sequencing was conducted. Data were also obtained from package inserts, meeting abstracts, and clinical registries.

STUDY SELECTION AND DATA EXTRACTION

All relevant published articles and abstracts on ipilimumab, vemurafenib, dabrafenib, and trametinib were reviewed. Clinical trial registries and meeting abstracts were used for ongoing studies.

DATA SYNTHESIS

The availability of new agents has made therapy selection more complex. Immunotherapy supporters reason that immunotherapy offers the best chance for long-term benefit and does not compromise the antitumor activity of subsequent BRAF inhibitors. Targeted therapy advocates rely on the high probability and rapid onset of response to BRAF inhibitors. Currently, there is insufficient evidence regarding the role of BRAF inhibitor at disease progression.

CONCLUSIONS

Therapy should be individualized based on patient- and disease-specific factors. Immunotherapy represents the best option for durable remission; however, targeted therapy is more appropriate for patients who are symptomatic or have rapidly growing tumors. The novel therapies have also demonstrated meaningful intracranial activity; thus, the presence of brain metastases should be taken into consideration in selecting therapy. Limited data exist about the continuation of BRAF inhibitors after therapeutic failure. Active research is ongoing to define the best option for patients with BRAF inhibitor refractory disease.

Novel treatments for melanoma brain metastases

BACKGROUND

The development of brain metastases is common in patients with melanoma and is associated with a poor prognosis. Treating patients with melanoma brain metastases (MBMs) is a major therapeutic challenge. Standard approaches with conventional chemotherapy are disappointing, while surgery and radiotherapy have improved outcomes.

METHODS

In this article, we discuss the biology of MBMs, briefly outline current treatment approaches, and emphasize novel and emerging therapies for MBMs.

RESULTS

The mechanisms that underlie the metastases of melanoma to the brain are unknown; therefore, it is necessary to identify pathways to target MBMs. Most patients with MBMs have short survival times. Recent use of immune-based and targeted therapies has changed the natural history of metastatic melanoma and may be effective for the treatment of patients with MBMs.

CONCLUSIONS

Developing a better understanding of the factors responsible for MBMs will lead to improved management of this disease. In addition, determining the optimal treatments for MBMs and how they can be optimized or combined with other therapies, along with appropriate patient selection, are challenges for the management of this disease.

Melanoma brain metastases: an unmet challenge in the era of active therapy

Metastatic disease to the brain is a frequent manifestation of melanoma and is associated with significant morbidity and mortality and poor prognosis. Surgery and stereotactic radiosurgery provide local control but less frequently affect the overall outcome of melanoma brain metastases (MBM). The role of systemic therapies for active brain lesions has been largely underinvestigated, and patients with active brain lesions are excluded from the vast majority of clinical trials. The advent of active systemic therapy has revolutionized the care of melanoma patients, but this benefit has not been systematically translated into intracranial activity. In this article, we review the biology and clinical outcomes of patients with MBM, and the evidence supporting the use of radiation, surgery, and systemic therapy in MBM. Prospective studies that included patients with active MBM have shown clinical intracranial activity that parallels systemic activity and support the inclusion of patients with active MBM in clinical trials involving novel agents and combination therapies.

Treatment of brain metastases in uncommon tumors

Melanoma spreads to the CNS with an incidence of 4 to 20%. Metastases from cancer of the colorectal and genitourinary tract, as well as sarcoma, are less frequent (1%). Surgery should be considered for single brain metastases in patients with controllable disease. Stereotactic needle biopsy may still be worthwhile to confirm diagnosis, and also in patients whose tumors are considered unresectable. Whole-brain radiotherapy is the treatment of choice for most brain metastases, since more than 70% of patients have multiple metastases at the time of diagnosis. Radiosurgery is particularly useful for patients unable to tolerate surgery and for patients with lesions inaccessible to surgery. Chemotherapy could be useful in patients with asymptomatic brain metastases and uncontrolled extracranial disease, depending on performance status and previous chemotherapy received.

Challenges relating to solid tumour brain metastases in clinical trials, part 1: patient population, response, and progression. A report from the RANO group

Therapeutic outcomes for patients with brain metastases need to improve. A critical review of trials specifically addressing brain metastases shows key issues that could prevent acceptance of results by regulatory agencies, including enrolment of heterogeneous groups of patients and varying definitions of clinical endpoints. Considerations specific to disease, modality, and treatment are not consistently addressed. Additionally, the schedule of CNS imaging and consequences of detection of new or progressive brain metastases in trials mainly exploring the extra-CNS activity of systemic drugs are highly variable. The Response Assessment in Neuro-Oncology (RANO) working group is an independent, international, collaborative effort to improve the design of trials in patients with brain tumours. In this two-part series, we review the state of clinical trials of brain metastases and suggest a consensus recommendation for the development of criteria for future clinical trials.

Concurrent whole brain radiotherapy and bortezomib for brain metastasis

Background

Survival of patients with brain metastasis particularly from historically more radio-resistant malignancies remains dismal. A phase I study of concurrent bortezomib and whole brain radiotherapy was conducted to determine the tolerance and safety of this approach in patients with previously untreated brain metastasis.

Methods

A phase I dose escalation study evaluated the safety of bortezomib (0.9, 1.1, 1.3, 1.5, and 1.7 mg/m²) given on days 1, 4, 8 and 11 of whole brain radiotherapy. Patients with confirmed brain metastasis were recruited for participation. The primary endpoint was the dose-limiting toxicity, defined as any ≥ grade 3 non-hematologic toxicity or grade ≥ 4 hematologic toxicity from the start of treatment to one month post irradiation. Time-to-Event Continual Reassessment Method (TITE-CRM) was used to determine dose escalation. A companion study of brain diffusion tensor imaging MRI was conducted on a subset of patients to assess changes in the brain that might predict delayed cognitive effects.

Results

Twenty-four patients were recruited and completed the planned therapy. Patients with melanoma accounted for 83% of all participants. The bortezomib dose was escalated as planned to the highest dose of 1.7 mg/m²/dose. No grade 4/5 toxicities related to treatment were observed. Two patients had grade 3 dose-limiting toxicities (hyponatremia and encephalopathy). A partial or minor response was observed in 38% of patients. Bortezomib showed greater demyelination in hippocampus-associated white matter structures on MRI one month after radiotherapy compared to patients not treated with bortezomib (increase in radial diffusivity +16.8% versus 4.8%; p = 0.0023).

Conclusions

Concurrent bortezomib and whole brain irradiation for brain metastasis is well tolerated at one month follow-up, but MRI changes that have been shown to predict delayed cognitive function can be detected within one month of treatment.

Update on the role of ipilimumab in melanoma and first data on new combination therapies

PURPOSE OF REVIEW

This article provides an update on the therapeutic role of the monoclonal antibody ipilimumab in melanoma. Recent therapeutic combinations, as well as directions for further investigations, will also be discussed.

RECENT FINDINGS

By blocking the interaction between CTLA-4 and B7 expressed on activated T lymphocytes and antigen-presenting cells, respectively, ipilimumab inhibits negative signals that physiologically downregulate T-cell activation and exerts its therapeutic activity by upregulating the antitumor activity of T lymphocytes. Ipilimumab has been the first agent to significantly improve the survival of metastatic melanoma patients and to provide long-term benefit to a sizeable proportion of patients treated within phase II/III studies and expanded access programs. On these premises, a number of studies combining ipilimumab with cytotoxic, antiangiogenic, and targeted agents have been most recently conducted.

SUMMARY

Ipilimumab is the prototype of a growing family of 'immunomodulating antibodies' and it has demonstrated that immunotherapy will play an increasingly important role in the new treatment approaches for cancer. Combinations of chemotherapy, radiation therapy, and targeted drugs with ipilimumab indicate that additive and synergistic antitumor activity can be achieved. Most importantly, they indicate that involving the immune system is a key strategy to improve the outcome in cancer patients.

Melanoma brain metastasis: overview of current management and emerging targeted therapies

The high rate of brain metastasis in patients with advanced melanoma has been a clinical challenge for oncologists. Despite considerable progress made in the management of advanced melanoma over the past two decades, improvement in overall survival has been elusive. This is due to the high incidence of CNS metastases, which progress relentlessly and which are only anecdotally responsive to systemic therapies. Surgery, stereotactic radiosurgery and whole-brain radiotherapy with or without cytotoxic chemotherapy remain the mainstay of treatment. However, new drugs have been developed based on our improved understanding of the molecular signaling mechanisms responsible for host immune tolerance and for melanoma growth. In 2011, the US FDA approved two agents, one antagonizing each of these processes, for the treatment of advanced melanoma. The first is ipilimumab, an anti-CTLA-4 monoclonal antibody that enhances cellular immunity and reduces tolerance to tumor-associated antigens. The second is vemurafenib, an inhibitor that blocks the abnormal signaling for melanoma cellular growth in tumors that carry the BRAF(V600E) mutation. Both drugs have anecdotal clinical activity for brain metastasis and are being evaluated in clinical trial settings. Additional clinical trials of newer agents involving these pathways are also showing promise. Therefore, targeted therapies must be incorporated into the multimodality management of melanoma brain metastasis.

Multidisciplinary approach to brain metastasis from melanoma; local therapies for central nervous system metastases

The overall treatment paradigm for melanoma brain metastases continues to evolve and reflects the relative radioresistance of this histology, as well as the effect of emerging systemic therapies with central nervous system (CNS) activity. Local therapies, including surgery, whole brain radiotherapy (WBRT), and stereotactic radiosurgery (SRS), play an important role in the multidisciplinary management of melanoma brain metastases. Treatment selection for local therapies must consider many factors: (1) size, number, and location of lesions, (2) presence or absence of neurological symptoms, (3) extracranial disease status, expected survival, age, and performance status, (4) prior treatment history, (5) expected treatment toxicities, and (6) predicted response to systemic therapies. The choice of treatment modalities for brain metastases is among the most controversial areas in oncology. There has been a trend toward reduced use of WBRT and increased reliance on SRS and surgery for melanoma brain metastases. Although no prospective randomized data exist comparing local therapies for melanoma brain metastases, several large retrospective studies suggest aggressive local treatment with modalities including surgery and SRS are associated with favorable outcomes in select patients. Multidisciplinary collaboration is required to facilitate a treatment plan that balances reduction in risk of neurological death and symptomatic progression against the risk of treatment-related toxicity.

Brain metastases

PURPOSE OF REVIEW

Brain metastases are the most common neurologic complication related to systemic cancer. With continued improvements in systemic treatment, the incidence is expected to increase. This article reviews the clinical presentation, pathophysiology, prognostic factors, and treatment of metastatic brain tumors.

RECENT FINDINGS

Brain metastases from systemic cancer are up to 10 times more common than primary malignant brain tumors and are a significant burden in the management of patients with advanced cancer. Common presenting symptoms include headache, focal weakness or numbness, mental status change, and seizure. Management and treatment of metastatic brain tumors is complex and dependent on several factors, including age, performance status, number of metastases at presentation, and status of systemic disease. At the time of diagnosis, most patients have more than one brain metastasis, and treatment has traditionally consisted of whole-brain radiation therapy (WBRT). For those patients with single brain metastases, aggressive local treatment with surgery or stereotactic radiosurgery (SRS) combined with WBRT has been shown to improve survival and neurologic outcomes compared with WBRT alone. In patients with a limited number of brain metastases, SRS alone is being increasingly explored as a treatment option that spares the upfront toxicity of WBRT. Currently, the role of chemotherapy is limited to experimental settings and salvage after radiation therapy.

SUMMARY

Patients with brain metastases have complex needs and require a multidisciplinary approach in order to optimize intracranial disease control while maximizing neurologic function and quality of life. Patients with multiple metastases, uncontrolled systemic disease, and poor functional status are typically treated with WBRT alone, whereas surgery and SRS may be used for additional local control in a subset of patients with fewer tumors and good functional status. The incorporation of neuropsychological outcomes, neurologic function, and quality of life as end points in future studies will offer further guidance for providing comprehensive care to patients with metastatic brain tumors.

Combining stereotactic radiosurgery and systemic therapy for brain metastases: a potential role for temozolomide

Brain metastases are unfortunately very common in the natural history of many solid tumors and remain a life-threatening condition, associated with a dismal prognosis, despite many clinical trials aimed at improving outcomes. Radiation therapy options for brain metastases include whole brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS). SRS avoids the potential toxicities of WBRT and is associated with excellent local control (LC) rates. However, distant intracranial failure following SRS remains a problem, suggesting that untreated intracranial micrometastatic disease is responsible for failure of treatment. The oral alkylating agent temozolomide (TMZ), which has demonstrated efficacy in primary malignant central nervous system tumors such as glioblastoma, has been used in early phase trials in the treatment of established brain metastases. Although results of these studies in established, macroscopic metastatic disease have been modest at best, there is clinical and preclinical data to suggest that TMZ is more efficacious at treating and controlling clinically undetectable intracranial micrometastatic disease. We review the available data for the primary management of brain metastases with SRS, as well as the use of TMZ in treating established brain metastases and undetectable micrometastatic disease, and suggest the role for a clinical trial with the aims of treating macroscopically visible brain metastases with SRS combined with TMZ to address microscopic, undetectable disease.

Treatment of melanoma brain metastases: a new paradigm

Brain metastases occur commonly in patients with metastatic melanoma, are associated with a poor prognosis, and cause significant morbidity. Both surgery and stereotactic radiosurgery are used to control brain metastases and, in selected patients, improve survival. In those with extensive brain involvement, whole-brain radiotherapy can alleviate symptoms. Historically, systemic therapy has had little role to play in the management of melanoma brain metastases; however, early clinical trials of BRAF inhibitors have shown promising activity. This review examines the evidence for local and systemic treatments in the management of patients with melanoma brain metastases. We present a new treatment algorithm for melanoma patients with brain metastases, which integrates the evolving evidence for the use of BRAF inhibitors.

Ipilimumab in patients with melanoma and brain metastases: an open-label, phase 2 trial

BACKGROUND

Brain metastases commonly develop in patients with melanoma and are a frequent cause of death of patients with this disease. Ipilimumab improves survival in patients with advanced melanoma. We aimed to investigate the safety and activity of this drug specifically in patients with brain metastases.

METHODS

Between July 31, 2008, and June 3, 2009, we enrolled patients with melanoma and brain metastases from ten US centres who were older than 16 years into two parallel cohorts. Patients in cohort A were neurologically asymptomatic and were not receiving corticosteroid treatment at study entry; those in cohort B were symptomatic and on a stable dose of corticosteroids. Patients were to receive four doses of 10 mg/kg intravenous ipilimumab, one every 3 weeks. Individuals who were clinically stable at week 24 were eligible to receive 10 mg/kg intravenous ipilimumab every 12 weeks. The primary endpoint was the proportion of patients with disease control, defined as complete response, partial response, or stable disease after 12 weeks, assessed with modified WHO criteria. Analyses of safety and efficacy included all treated patients. This trial is registered with ClinicalTrials.gov, number NCT00623766.

FINDINGS

We enrolled 72 patients: 51 into cohort A and 21 into cohort B. After 12 weeks, nine patients in cohort A exhibited disease control (18%, 95% CI 8-31), as did one patient in cohort B (5%, 0·1-24). When the brain alone was assessed, 12 patients in cohort A (24%, 13-38) and two in cohort B (10%, 1-30) achieved disease control. We noted disease control outside of the brain in 14 patients (27%, 16-42) in cohort A and in one individual (5%, 0·1-24) in cohort B. The most common grade 3 adverse events in cohort A were diarrhoea (six patients [12%]) and fatigue (six [12%]); in cohort B, they were dehydration (two individuals [10%]), hyperglycaemia (two [10%]), and increased concentrations of serum aspartate aminotransferase (two [10%]). One patient in each cohort had grade 4 confusion. The most common grade 3 immune-related adverse events were diarrhoea (six patients [12%]) and rash (one [2%]) in cohort A, and rash (one individual [5%]) and increased concentrations of serum aspartate aminotransferase (two [10%]) in cohort B. One patient in cohort A died of drug-related complications of immune-related colitis.

INTERPRETATION

Ipilimumab has activity in some patients with advanced melanoma and brain metastases, particularly when metastases are small and asymptomatic. The drug has no unexpected toxic effects in this population.

FUNDING

Bristol-Myers Squibb.

Albendazole sensitizes cancer cells to ionizing radiation

Background

Brain metastases afflict approximately half of patients with metastatic melanoma (MM) and small cell lung cancer (SCLC) and represent the direct cause of death in 60 to 70% of those affected. Standard of care remains ineffective in both types of cancer with the challenge of overcoming the blood brain barrier (BBB) exacerbating the clinical problem. Our purpose is to determine and characterize the potential of albendazole (ABZ) as a cytotoxic and radiosensitizing agent against MM and SCLC cells.

Methods

Here, ABZ's mechanism of action as a DNA damaging and microtubule disrupting agent is assessed through analysis of histone H2AX phosphorylation and cell cyle progression. The cytotoxicity of ABZ alone and in combination with radiation therapy is determined though clonogenic cell survival assays in a panel of MM and SCLC cell lines. We further establish ABZ's ability to act synergistically as a radio-sensitizer through combination index calculations and apoptotic measurements of poly (ADP-ribose) polymerase (PARP) cleavage.

Results

ABZ induces DNA damage as measured by increased H2AX phosphorylation. ABZ inhibits the growth of MM and SCLC at clinically achievable plasma concentrations. At these concentrations, ABZ arrests MM and SCLC cells in the G2/M phase of the cell cycle after 12 hours of treatment. Exploiting the notion that cells in the G2/M phase are the most sensitive to radiation therapy, we show that treatment of MM and SCLC cells treated with ABZ renders them more sensitive to radiation in a synergistic fashion. Additionally, MM and SCLC cells co-treated with ABZ and radiation exhibit increased apoptosis at 72 hours.

Conclusions

Our study suggests that the orally available antihelminthic ABZ acts as a potent radiosensitizer in MM and SCLC cell lines. Further evaluation of ABZ in combination with radiation as a potential treatment for MM and SCLC brain metastases is warranted.

Surgical brain metastases: management and outcome related to prognostic indexes: a critical review of a ten-year series

Brain metastasis are the most common neoplastic lesions of the nervous system. Many cancer patients are diagnosed on the basis of a first clinical presentation of cancer on the basis of a single or multiple brain lesions. Brain metastases are manifestations of primary disease progression and often determine a poor prognosis. Not all patients with a brain metastases undergo surgery: many are submitted to alternative or palliative treatments. Management of patients with brain metastases is still controversial, and many studies have been developed to determine which is the best therapy. Furthermore, management of patients operated for a brain metastasis is often difficult. Chemotherapy, stereotactic radiosurgery, panencephalic radiation therapy, and surgery, in combination or alone, are the means most commonly used. We report our experience in the management of a ten-year series of surgical brain metastasis and discuss our results in the preoperative and postoperative management of this complex condition.

New therapeutic options in the medical management of advanced melanoma

During the past 3 decades, the incidence, morbidity, and mortality of malignant melanoma have increased dramatically. Advanced melanoma has remained a disease that is for the most part incurable and has challenged all therapeutic efforts to make a dent in its natural history. Recent advances in the understanding of the molecular alterations in melanoma and in the immunologic mechanisms playing a role in this malignancy have brought hope that significant progress can be achieved, as evidenced by early encouraging clinical data. This review will summarize these recent developments and their impact on current clinical practice.

Cerebral melanoma metastases: a critical review on diagnostic methods and therapeutic options

Malignant melanoma represents the third most common cause for cerebral metastases after breast and lung cancer. Central nervous system (CNS) metastases occur in 10 to 40% of patients with melanoma. Most of the symptoms of CNS melanoma metastases are unspecific and depend on localization of the lesion. All patients with new neurological signs and a previous primary melanoma lesion must be investigated. Although primary diagnosis may rely on computed tomography scan, magnetic resonance images are usually used in order to study more precisely the characteristics of the lesions in and to embase the surgical plan. Other possible complementary exams are: positron emission tomography, iofetamine cintilography, immunohistochemistry of liquor, monoclonal antibody immunocytology, optical coherence tomography, and transcriptase-polymerase chain reaction. Treatment procedures are indicated based on patient clinical status, presence of unique or multiple lesions, and family agreement. Often surgery, radiosurgery, whole brain radiotherapy, and chemotherapy are combined in order to obtain longer remissions and optimal symptom relieve. Corticoids may be also useful in those cases that present with remarkable peritumoral edema and important mass effect. Despite of the advance in therapeutic options, prognosis for patients with melanoma brain metastases remains poor with a median survival time of six months after diagnosis.

Riluzole enhances ionizing radiation-induced cytotoxicity in human melanoma cells that ectopically express metabotropic glutamate receptor 1 in vitro and in vivo

PURPOSE

Brain metastases are a common preterminal event in patients with metastatic melanoma and require radiation therapy. Our group has previously shown that human GRM1 (hGRM1) expressing melanoma cells release excess extracellular glutamate and are growth inhibited by riluzole, an inhibitor of glutamate release. Riluzole-treated cells accumulate in G(2)/M phase of the cell cycle at 24 hours, and then undergo apoptotic cell death. We evaluated whether riluzole enhanced radiosensitivity in melanoma cells.

EXPERIMENTAL DESIGN

Clonogenic assays were performed to evaluate clonogenic survival after treatment in hGRM1 expressing and nonexpressing melanoma cells. Western immunoblots were performed to confirm apoptotic cell death. A xenograft mouse model was used to validate the in vitro experiments. Tumors harvested from the xenografts were fixed and stained for apoptosis and DNA damage markers.

RESULTS

In the hGRM1-positive cell lines C8161 and UACC903, riluzole enhanced the lethal effects of ionizing radiation; no difference was seen in the hGRM1-negative UACC930 cell line. C8161 cells treated with riluzole plus irradiation also showed the highest levels of the cleaved forms of PARP and caspase-3; excised C8161 xenografts showed the greatest number of apoptotic cells by immunohistochemistry (P < 0.001). On cell cycle analysis, a sequence-dependent enrichment in the G(2)/M phase was shown with the combination of riluzole and irradiation. Xenografts treated with riluzole and weekly radiation fractions showed significant growth inhibition and revealed markedly increased DNA damage.

CONCLUSIONS

We have shown, in vitro and in vivo, that the combination of riluzole and ionizing radiation leads to greater cytotoxicity. These results have clinical implications for patients with brain metastases receiving whole brain radiation therapy.