Long-term stabilization of leptomeningeal disease with whole-brain radiation therapy in a patient with metastatic melanoma treated with vemurafenib: a case report

A case report and literature review on primary intracranial malignant melanoma: Challenges and insights

INTRODUCTION AND IMPORTANCE

Primary central nervous system (CNS) melanoma is a rare entity. Primary CNS malignant melanomas account for 1 % of melanomas and 0.07 % of intracranial tumours. These are highly aggressive and are associated with poor prognosis. Herein, we have discussed one such rare case of PIMM.

CASE PRESENTATION

62-year-old man with primary CNS melanoma underwent craniotomy and resection of left temporal lesion. Postoperative MRI showed no evidence of residual disease. He received 28 fractions of radiation. Follow-up MRI showed no evidence of disease. However, he later developed worsening symptoms and repeat imaging revealed disease progression with hydrocephalus and drop metastasis to spine. He underwent VP shunting and was started on Temozolomide. He progressively declined functionally and eventually died from his disease.

CLINICAL DISCUSSION

Primary CNS melanoma is characterized by its rarity, challenging diagnosis, and aggressive behaviour. Current literature suggests limited treatment options, which depend on complete resection of the primary tumour. Molecular analysis may play a key role in deciding future treatment options, including immune checkpoint inhibitors and targeted therapies targeting the BRAFV600E mutation.

CONCLUSION

Primary intracranial malignant melanoma (PIMM) is an extremely rare tumour of CNS, and its treatment paradigm is very limited based on available literature. Currently any long-term survival depends on the complete resection of tumour. Our case is unique as it talks about the limited therapeutic options in case of rapidly declining performance status in a resource constraint setting.

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

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

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.

Leptomeningeal Metastases in Melanoma Patients: An Update on and Future Perspectives for Diagnosis and Treatment

Leptomeningeal disease (LMD) is a devastating complication of cancer with a particularly poor prognosis. Among solid tumours, malignant melanoma (MM) has one of the highest rates of metastasis to the leptomeninges, with approximately 10-15% of patients with advanced disease developing LMD. Tumour cells that metastasise to the brain have unique properties that allow them to cross the blood-brain barrier, evade the immune system, and survive in the brain microenvironment. Metastatic colonisation is achieved through dynamic communication between metastatic cells and the tumour microenvironment, resulting in a tumour-permissive milieu. Despite advances in treatment options, the incidence of LMD appears to be increasing and current treatment modalities have a limited impact on survival. This review provides an overview of the biology of LMD, diagnosis and current treatment approaches for MM patients with LMD, and an overview of ongoing clinical trials. Despite the still limited efficacy of current therapies, there is hope that emerging treatments will improve the outcomes for patients with LMD.

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

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

Leptomeningeal Disease (LMD) in Patients with Melanoma Metastases

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

Leveraging Molecular and Immune-Based Therapies in Leptomeningeal Metastases

Leptomeningeal metastases represent an aggressive stage of cancer with few durable treatment options. Improved understanding of cancer biology, neoplastic reliance on oncogenic driver mutations, and complex immune system interactions have resulted in an explosion in cancer-directed therapy in the last two decades to include small molecule inhibitors and immune checkpoint inhibitors. Most of these therapeutics are underexplored in patients with leptomeningeal metastases, limiting extrapolation of extracranial and even intracranial efficacy outcomes to the unique leptomeningeal space. Further confounding our interpretation of drug activity in the leptomeninges is an incomplete understanding of drug penetration through the blood-cerebrospinal fluid barrier of the choroid plexus. Nevertheless, a number of retrospective studies and promising prospective trials provide evidence of leptomeningeal activity of several small molecule and immune checkpoint inhibitors and underscore potential areas of further therapeutic development for patients harboring leptomeningeal disease.

Leptomeningeal Metastases: New Opportunities in the Modern Era

Leptomeningeal metastases arise from cancer cell entry into the subarachnoid space, inflicting significant neurologic morbidity and mortality across a wide range of malignancies. The modern era of cancer therapeutics has seen an explosion of molecular-targeting agents and immune-mediated strategies for patients with breast, lung, and melanoma malignancies, with meaningful extracranial disease control and improvement in patient survival. However, the clinical efficacy of these agents in those with leptomeningeal metastases remains understudied, due to the relative rarity of this patient population, the investigational challenges associated with studying this dynamic disease state, and brisk disease pace. Nevertheless, retrospective studies, post hoc analyses, and small prospective trials in the last two decades provide a glimmer of hope for patients with leptomeningeal metastases, suggesting that several cancer-directed strategies are not only active in the intrathecal space but also improve survival against historical odds. The continued development of clinical trials devoted to patients with leptomeningeal metastases is critical to establish robust efficacy outcomes in this patient population, define drug pharmacokinetics in the intrathecal space, and uncover new avenues for treatment in the face of leptomeningeal therapeutic resistance.

Adjuvant systemic treatment for high-risk resected non-cutaneous melanomas: What is the evidence?

Non-cutaneous melanomas (mucosal, uveal, leptomeningeal, unknown primaries) represent around 5-10 % of all melanoma diagnoses. Non-cutaneous melanomas demonstrate differences in tumour biology, generally present with more advanced stages and have an overall poorer prognosis compared to skin melanomas. The cornerstone of their treatment is surgery followed by radiotherapy in some cases. Unfortunately, in many of these patients their melanoma will recur. Adjuvant therapy for non-cutaneous melanomas remains controversial. To date, almost all of the tested adjuvant agents have failed to demonstrate any benefit; the two randomised positive trials were criticized for methodological reasons, small sample size and conflicting results. The aim of this review is to assess the current evidence on systemic adjuvant treatments for high-risk resected non-cutaneous melanomas. We also provide a summary table with the currently recruiting clinical trials in these settings and we discuss some strategies to improve trial design in this particularly niche area of oncology.

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

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

Leptomeningeal disease from melanoma-Poor prognosis despite new therapeutic modalities

OBJECTIVE

The development of leptomeningeal disease (LMD) among melanoma patients is associated with short survival. Unspecific clinical symptoms and imprecise diagnostic criteria often delay diagnosis. Because melanoma patients with LMD have been excluded from most clinical trials, the efficacy of immune checkpoint blockade (ICB) and targeted therapies (TTs) has not been adequately investigated among these patients.

METHODS

We performed a retrospective study in two tertiary-referral skin cancer centres to evaluate the clinical characteristics, diagnostics, treatments, and overall survival (OS) of melanoma patients with LMD between June 2011 and March 2019.

RESULTS

In total, 52 patients were included. The median age at LMD diagnosis was 58 years. Most patients (n = 30, 58%) were men. The median time from the first diagnosis of unresectable disease to the first diagnosis of LMD was 8.5 months (range 0-91.5 months). Most patients (65%, n = 34) were BRAF V600 mutated. Sixteen patients (31%) presented with LMD only, whereas 36 patients (69%) presented with concomitant brain metastases at LMD diagnosis. Eleven patients (21%) showed no evidence of extracranial disease. Forty-four patients (85%) had clinical symptoms at LMD diagnosis. Forty-two patients (81%) had received at least one prior therapy. Forty patients (77%) received at least one treatment after LMD diagnosis, including TT (n = 17), ICB (n = 13), bevacizumab (n = 1), radiotherapy (n = 3), and intrathecal chemotherapy (n = 1); five patients received both TT and ICB. Twelve patients (23%) received no treatment because of rapid progression of LMD. The median OS for the entire cohort was 2.9 months (95% confidence interval [CI] 1.7-4.1). Among patients receiving systemic therapy, OS was 3.7 months (95% CI 2.4-4.9).

CONCLUSIONS

Systemic treatment with TT or ICB seems to improve OS among patients with LMD. However, despite new therapy modalities, the prognosis of LMD remains poor.

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.

Long-term control of leptomeningeal disease after radiation therapy and nivolumab in a metastatic melanoma patient

Background: Leptomeningeal disease (LMD) from melanoma is rapidly fatal with median overall survival between 6.9 weeks and 3.5 months. It is not known whether immune checkpoint inhibitors have a role in treating LMD. Case presentation: We report a 33-year-old male patient who developed LMD from a BRAF V600E-mutated melanoma brain metastasis, despite prior treatment with surgical resection, radiotherapy and dabrafenib/trametinib. He underwent whole brain radiotherapy with stereotactic radiotherapy to the lumbosacral spine, and was started on nivolumab, which led to prolonged remission lasting 2 years and 3 months, before disease progression and death. Conclusion: This is the first case report to highlight a potential long-term efficacy of radiotherapy and anti-PD-1 immunotherapy, in treating LMD from metastatic melanoma that is resistant to targeted therapy.

Leptomeningeal metastasis from solid tumors

Central nervous system (CNS) metastasis from systemic cancers can involve the brain parenchyma, leptomeninges (pia, subarachnoid space and arachnoid mater), and dura. Leptomeningeal metastases (LM), also known by different terms including neoplastic meningitis and carcinomatous meningitis, occur in both solid tumors and hematologic malignancies. This review will focus exclusively on LM arising from solid tumors with a goal of providing the reader an understanding of the epidemiology, pathophysiology, clinical presentation, prognostication, current management and future directions.

Targeted Therapy After Brain Radiotherapy for BRAF-Mutated Melanoma With Extensive Ependymal Disease With Prolonged Survival: Case Report and Review of the Literature

Melanoma brain metastasis with ependymal spread/metastases is uncommon. These cases are frequently classified together with leptomeningeal disease. However, the commonalities and differences in the underlying pathophysiology and clinical outcomes between these two types of spread are not clear. Very few reports on long term outcome and durable central nervous system (CNS) disease control have been reported in the literature. Here, we report a case of a 45 year-old Caucasian lady with BRAF-V600E mutant metastatic melanoma to the brain who had whole brain radiotherapy followed by two Gamma knife radiosurgery treatments for localized disease progression. She then developed extensive ependymal disease progression with no evidence of leptomeningeal spread. She was treated with a repeat course of whole brain radiotherapy and maintained on BRAF and MEK inhibitors with durable CNS disease control for more than a year. This study reviews the management of BRAF-V600E mutant melanoma with ependymal involvement. Management using radiation therapy with maintenance targeted therapy seems to be a reasonable approach to this challenging disease.

Combination of novel systemic agents and radiotherapy for solid tumors - part I: An AIRO (Italian association of radiotherapy and clinical oncology) overview focused on treatment efficacy

Over the past century, technologic advances have promoted the evolution of radiation therapy into a precise treatment modality allowing for the maximal administration of dose to tumors while sparing normal tissues. In parallel with this technological maturation, the rapid expansion in understanding the basic biology and heterogeneity of cancer has led to the development of several compounds that target specific pathways. Many of them are in advanced steps of clinical development for combination treatments with radiotherapy, and can be incorporated into radiation oncology practice for a personalized approach to maximize the therapeutic gain. This review describes the rationale for combining novel agents with radiation, and provides an overview of the current landscape focused on treatment efficacy.

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.

Leptomeningeal metastasis

Leptomeningeal metastasis (LM) results from dissemination of cancer cells to both the leptomeninges (pia and arachnoid) and cerebrospinal fluid (CSF) compartment. Breast cancer, lung cancer, and melanoma are the most common solid tumors that cause LM. Recent approval of more active anticancer therapies has resulted in improvement in survival that is partly responsible for an increased incidence of LM. Neurologic deficits, once manifest, are mostly irreversible, and often have a significant impact on patient quality of life. LM-directed therapy is based on symptom palliation, circumscribed use of neurosurgery, limited field radiotherapy, intra-CSF and systemic therapies. Novel methods of detecting LM include detection of CSF circulating tumor cells and tumor cell-free DNA. A recent international guideline for a standardization of response assessment in LM may improve cross-trial comparisons as well as within-trial evaluation of treatment. An increasing number of retrospective studies suggest that molecular-targeted therapy, such as EGFR and ALK inhibitors in lung cancer, trastuzumab in HER2+ breast cancer, and BRAF inhibitors in melanoma, may be effective as part of the multidisciplinary management of LM. Prospective randomized trials with standardized response assessment are needed to further validate these preliminary findings.

Preliminary Investigation of Focused Ultrasound-Facilitated Drug Delivery for the Treatment of Leptomeningeal Metastases

Leptomeningeal metastases (LM) are a serious complication of cancer in the central nervous system (CNS) and are diagnosed in approximately 5% of patients with solid tumors. Effective treatment using systemically administered therapeutics is hindered by the barriers of the CNS. Ultrasound can mediate delivery of drugs through these barriers. The goal of this study was to test the feasibility of using ultrasound-mediated drug delivery to improve the treatment of LM. LM was induced in the spinal cord of athymic rats by injecting HER2-expressing breast cancer cells into the subarachnoid space of the thoracic spine. Animals were divided into three groups: no treatment (n = 5), trastuzumab only (n = 6) or trastuzumab + focused ultrasound + microbubbles (FUS + MBs) (n = 7). Animals in groups 2 and 3 were treated weekly with intravenous trastuzumab +/− FUS + MBs for three weeks. Suppression in tumor growth was qualitatively observed by MRI in the group receiving ultrasound, and was confirmed by a significant difference in the tumor volume measured from the histology data (25 ± 17 mm³ vs 8 ± 5 mm³, p = 0.04 in the trastuzumab-only vs trastuzumab + FUS + MBs). This pilot study demonstrates the potential of ultrasound-mediated drug delivery as a novel treatment for LM. Future studies will extend this work to larger cohorts and the investigation of LM arising from other cancers.

Experimental Treatments for Leptomeningeal Metastases From Solid Malignancies

BACKGROUND

Leptomeningeal metastasis is a consequence of advanced solid malignancies and has limited treatment options. It is possible that it is becoming more common as the leptomeninges act as a sanctuary site for recurrence from systemic cancer.

METHODS

Potential targeted and immunotherapy agents for the most common types of solid-tumor leptomeningeal metastasis are reviewed, as are their dosing/delivery strategies and novel, immunological approaches.

RESULTS

Historically, patients with leptomeningeal metastasis have been excluded from clinical trials, and data on the management of leptomeningeal metastasis come from single case reports and retrospective analyses.

CONCLUSION

For the first time ever, published reports suggest the tide may be turning in this challenging disease.

Use of Systemic Therapy Concurrent With Cranial Radiotherapy for Cerebral Metastases of Solid Tumors

The incidence of brain metastases of solid tumors is increasing. Local treatment of brain metastases is generally straightforward: cranial radiotherapy (e.g., whole-brain radiotherapy or stereotactic radiosurgery) or resection when feasible. However, treatment becomes more complex when brain metastases occur while other metastases, outside of the central nervous system, are being controlled with systemic therapy (chemotherapeutics, molecular targeted agents, or monoclonal antibodies). It is known that some anticancer agents can increase the risk for neurotoxicity when used concurrently with radiotherapy. Increased neurotoxicity decreases quality of life, which is undesirable in this predominantly palliative patient group. Therefore, it is of utmost importance to identify the compounds that should be temporarily discontinued when cranial radiotherapy is needed.This review summarizes the (neuro)toxicity data for combining systemic therapy (chemotherapeutics, molecular targeted agents, or monoclonal antibodies) with concurrent radiotherapy of brain metastases. Because only a limited amount of high-level data has been published, a risk assessment of each agent was done, taking into account the characteristics of each compound (e.g., lipophilicity) and the microenvironment of brain metastasis. The available trials suggest that only gemcitabine, erlotinib, and vemurafenib induce significant neurotoxicity when used concurrently with cranial radiotherapy. We conclude that for most systemic therapies, the currently available literature does not show an increase in neurotoxicity when these therapies are used concurrently with cranial radiotherapy. However, further studies are needed to confirm safety because there is no high-level evidence to permit definitive conclusions. The Oncologist 2017;22:222-235Implications for Practice: The treatment of symptomatic brain metastases diagnosed while patients are receiving systemic therapy continues to pose a dilemma to clinicians. Will concurrent treatment with cranial radiotherapy and systemic therapy (chemotherapeutics, molecular targeted agents, and monoclonal antibodies), used to control intra- and extracranial tumor load, increase the risk for neurotoxicity? This review addresses this clinically relevant question and evaluates the toxicity of combining systemic therapies with cranial radiotherapy, based on currently available literature, in order to determine the need to and interval to interrupt systemic treatment.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Avoiding Severe Toxicity From Combined BRAF Inhibitor and Radiation Treatment: Consensus Guidelines from the Eastern Cooperative Oncology Group (ECOG)

BRAF kinase gene V600 point mutations drive approximately 40% to 50% of all melanomas, and BRAF inhibitors (BRAFi) have been found to significantly improve survival outcomes. Although radiation therapy (RT) provides effective symptom palliation, there is a lack of toxicity and efficacy data when RT is combined with BRAFi, including vemurafenib and dabrafenib. This literature review provides a detailed analysis of potential increased dermatologic, pulmonary, neurologic, hepatic, esophageal, and bowel toxicity from the combination of BRAFi and RT for melanoma patients described in 27 publications. Despite 7 publications noting potential intracranial neurotoxicity, the rates of radionecrosis and hemorrhage from whole brain RT (WBRT), stereotactic radiosurgery (SRS), or both do not appear increased with concurrent or sequential administration of BRAFis. Almost all grade 3 dermatitis reactions occurred when RT and BRAFi were administered concurrently. Painful, disfiguring nondermatitis cutaneous reactions have been described from concurrent or sequential RT and BRAFi administration, which improved with topical steroids and time. Visceral toxicity has been reported with RT and BRAFi, with deaths possibly related to bowel perforation and liver hemorrhage. Increased severity of radiation pneumonitis with BRAFi is rare, but more concerning was a potentially related fatal pulmonary hemorrhage. Conversely, encouraging reports have described patients with leptomeningeal spread and unresectable lymphadenopathy rendered disease free from combined RT and BRAFi. Based on our review, the authors recommend holding BRAFi and/or MEK inhibitors ≥3 days before and after fractionated RT and ≥1 day before and after SRS. No fatal reactions have been described with a dose <4 Gy per fraction, and time off systemic treatment should be minimized. Future prospective data will serve to refine these recommendations.

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

Melanoma frequently metastasizes to the brain, with CNS involvement being clinically evident in ∼30% of patients (as high as 75% at autopsy). In ∼5% cases melanoma cells also metastasize to the leptomeninges, the sub-arachnoid space and cerebrospinal fluid (CSF). Patients with leptomeningeal melanoma metastases (LMM) have the worst prognosis and are characterized by rapid disease progression (mean survival 8-10 weeks) and a death from neurological causes. The recent years have seen tremendous progress in the development of targeted and immune therapies for melanoma that has translated into an increased survival benefit. Despite these gains, the majority of patients fail therapy and there is a suspicion that the brain and the leptomeninges are a "sanctuary" sites for melanoma cells that escape both targeted therapy and immunologic therapies. Emerging evidence suggests that (1) Cancer cells migrating to the CNS may have unique molecular properties and (2) the CNS/leptomeningeal microenvironment represents a pro-survival niche that influences therapeutic response. In this Mini-Review, we will outline the clinical course of LMM development and will describe how the intracranial immune and cellular microenvironments offer both opportunities and challenges for the successful management of this disease. We will further discuss the latest data demonstrating the potential use of BRAF inhibitors and immune therapy in the management of LMM, and will review future potential therapeutic strategies for the management of this most devastating complication of advanced melanoma.

Radiotherapy with BRAF inhibitor therapy for melanoma: progress and possibilities

The introduction of small molecule BRAFV600 kinase inhibitors represents a milestone in the targeted therapy of patients with metastatic melanoma by a significant increase in therapeutic efficacy in terms of overall and progression-free survival compared with conventional chemotherapy. Beside BRAFV600 inhibitor treatment, radiotherapy is a further mainstay for the therapy of metastatic melanoma and thus a concomitant or sequential application of BRAFV600 inhibitors and radiotherapy is inevitable. Recent reports show a significant radiosensitization of the irradiated healthy tissue in patients with melanoma after the combination of radiotherapy and BRAFV600 inhibitors, evoking concern in clinical practice. We review interactions of BRAFV600 inhibitors and radiation with regard to antitumor effects and an increased radiotoxicity in the healthy tissue.

Primary Intracranial Melanoma with Early Leptomeningeal Spread: A Case Report and Treatment Options Available

Primary CNS melanomas are rare and they constitute about 1% of all cases of melanomas and 0.07% of all brain tumors. These tumors are aggressive in nature and may metastasise to other organs. Till date less than 25 cases have been reported in the literature. The primary treatment for local intraparenchymal tumours is complete resection and/or radiotherapy and it is associated with good survival. However once there is disease spread to leptomeninges the overall median survival is around 10 weeks. In this case report we describe a primary intracranial melanoma without any dural attachment in 16-year-old boy who had radical excision of the tumor followed by radiotherapy who eventually had rapidly developed leptomeningeal disease and review the literature with a focus on the clinic pathological, radiological, and treatment options.

Intrathecal Administration of Tumor-Infiltrating Lymphocytes Is Well Tolerated in a Patient with Leptomeningeal Disease from Metastatic Melanoma: A Case Report

Patients with leptomeningeal disease (LMD) from melanoma have very poor outcomes and few treatment options. We present a case of intrathecal (i.t.) administration of autologous tumor-infiltrating lymphocytes (TIL) in a patient with LMD from metastatic melanoma. The patient developed LMD after previous treatments with surgery, high-dose bolus interleukin-2 (HD IL2), and systemic TIL infusion and experienced radiographic progression after intrathecal IL2 (i.t. IL2) therapy. The patient received weekly treatment with increasing numbers of i.t. TIL followed by twice-weekly i.t. IL2. The patient received three i.t. TIL infusions and did not experience any toxicities beyond those expected with i.t. IL2 therapy. Analysis of cerebrospinal fluid demonstrated increased inflammatory cytokines following the i.t.

TREATMENTS

Subsequent imaging demonstrated disease stabilization, and neurological deficits also remained stable. The patient expired 5 months after the initiation of i.t. TIL therapy with disease progression in the brain, liver, lung, and peritoneal and retroperitoneal lymph nodes, but without LMD progression. These results demonstrate the safety of i.t. administration of TIL in melanoma patients with LMD and support the feasibility of conducting a prospective clinical trial to determine this therapy's clinical benefit among these patients.

Prolonged survival of a patient with metastatic leptomeningeal melanoma treated with BRAF inhibition-based therapy: a case report

Background

Leptomeningeal metastasis of melanoma is a devastating complication with a grave prognosis, and there are no known effective standard treatments. Although selective BRAF inhibitors have demonstrated a significant clinical activity in patients with metastatic melanoma harboring a BRAF mutation, the clinical benefit of BRAF inhibitor-based therapy in leptomeningeal disease is not clear.

Case presentation

We present a case of prolonged survival of a patient with BRAF V600E-mutant leptomeningeal disease who was treated with vemurafenib followed by whole brain radiation and a combination of dabrafenib and trametinib. Both vemurafenib and the sequential treatment of radiation and dabrafenib/trametinib led to regression of the leptomeningeal disease, and the patient survived for 19 months after the diagnosis of the leptomeningeal disease.

Conclusion

This case suggests a possible clinically meaningful benefit of BRAF inhibitor-based therapy and a need for close investigation of this therapeutic approach in patients with this devastating disease.

Radiation necrosis mimicking rapid intracranial progression of melanoma metastasis in two patients treated with vemurafenib

Optimal treatment of metastases to the central nervous system (CNS) in patients with malignant melanoma remains a clinical challenge. In particular, for patients with BRAF-mutant melanoma and CNS metastases, much remains unknown about the safety and efficacy of the novel BRAF-targeted agents when administered in close sequence with radiation. We report two cases of rapid development of CNS radiation necrosis in patients with metastatic melanoma treated with the BRAF inhibitor, vemurafenib, closely sequenced with stereotactic radiosurgery or fractionated stereotactic radiation therapy. In the absence of prospective safety data from clinical trials, we advise vigilance in monitoring patients with BRAF-mutant melanoma whose treatment plan includes CNS radiation and vemurafenib and caution when assessing treatment response within the CNS in these patients.

Leptomeningeal metastases from a primary central nervous system melanoma: a case report and literature review

Primary central nervous system (CNS) melanoma is a type of rare and aggressive tumor that can easily spread to the leptomeninges, and in fact, leptomeningeal metastasis is one of the most serious complications in patients with this carcinoma. Prognosis is extremely poor if a CNS melanoma has metastasized, and there are no effective treatments. Here, we present a case of a 37-year-old woman who presented with horizontal diplopia and progressive headache. Magnetic resonance imaging findings were consistent with the diagnosis of melanoma. The results of cytological examination of cerebrospinal fluid (CSF) showed malignant cells characteristic of melanoma. No extracranial lesions were observed. All of the available evidence confirmed a diagnosis of leptomeningeal metastases from a primary CNS melanoma. The patient received aggressive treatment, which consisted of concurrent radiotherapy and weekly intra-CSF methotrexate (MTX) followed by adjuvant monthly intra-CSF MTX. Her survival time was 13 months after diagnosis. This case report suggests that the modality of concurrent radiotherapy and weekly intra-CSF MTX followed by adjuvant monthly intra-CSF MTX may be used as the mainstay of treatment for such patients.

Incidence and characteristics of melanoma brain metastases developing during treatment with vemurafenib

Vemurafenib is indicated for the treatment of patients with BRAF (V600)-mutant metastatic melanoma. We studied for the first time the characteristics of brain metastases developed during treatment with vemurafenib in real-life conditions. We included all patients treated over 3 years with vemurafenib in our department for metastatic melanoma without initial brain involvement. Our primary endpoint was to assess the incidence of brain metastases in these patients. Our secondary endpoints were to identify the risk factors for metastases occurrence and their characteristics and course. In our retrospective cohort of 86 patients, 20% had developed brain metastases on average 5.3 months after vemurafenib initiation. The median follow-up was 9 months (1-26 months). Radiological examinations revealed multiple brain metastases in 41% of patients. The only risk factor for metastasis occurrence identified was a high number of metastatic sites when initiating vemurafenib (p = 0.045). Metastasis development was associated with a trend toward a decrease in overall survival from 12.8 to 8.5 months (p = 0.07) and a significant decrease in progression-free survival from 7 to 5 months (p = 0.04). Among the patients who developed brain metastases, 82% died, of whom 64% within 3 months, versus 58% of patients without brain metastases over the same period. The extra-cerebral disease was well controlled in 59% of patients during brain progression. In vemurafenib-treated melanoma patients, brain metastases are frequent and associated with a particularly poor prognosis. Because of their high frequency in patients with controlled extra-cerebral disease, brain explorations should be systematically performed during treatment.

The use of systemic therapies for the treatment of brain metastases in metastatic melanoma: opportunities and unanswered questions

The development of brain metastases is common in patients with metastatic melanoma and heralds a particularly poor prognosis. The development of the immunological agent ipilimumab and targeted treatments such as the selective BRAF inhibitor vemurafenib have revolutionised the treatment of metastatic disease. Evidence from clinical trials suggest these drugs may be effective in the treatment of brain metastases from melanoma. However efficacy may be limited by a lack of penetration of the blood brain barrier (BBB) and by multi substrate efflux pumps expressed on the BBB. The role and sequencing of radiotherapy, both whole brain and stereotactic radiotherapy, is yet to be determined but combinations of radiotherapy and systemic therapies may further increase the effects of these drugs on brain metastases. Considering the impact of brain metastases on morbidity and mortality in metastatic melanoma, future research into systemic drug therapy for the treatment of brain metastases and improvements in BBB penetrance should be a priority.