Concurrent Administration of Immune Checkpoint Inhibitors and Stereotactic Radiosurgery Is Well-Tolerated in Patients With Melanoma Brain Metastases: An International Multicenter Study of 203 Patients

BACKGROUND

Melanoma brain metastases are commonly treated with stereotactic radiosurgery (SRS) and immune checkpoint inhibitors (ICIs). However, the toxicity of these 2 treatments is largely unknown when administered concurrently.

OBJECTIVE

To evaluate the risk of radiation necrosis (RN) with concurrent and nonconcurrent SRS and ICIs.

METHODS

The guidelines from the Strengthening the Reporting of Observational Studies in Epidemiology checklist were used. Inverse probability of treatment weighting, univariable and multivariable logistic regression, and the Kaplan-Meier method was utilized.

RESULTS

There were 203 patients with 1388 brain metastases across 11 international institutions in 4 countries with a median follow-up of 15.6 months. The rates of symptomatic RN were 9.4% and 8.2% in the concurrent and nonconcurrent groups, respectively ( P =.766). On multivariable logistic regression, V12 ≥ 10 cm 3 (odds ratio [OR]: 2.76; P =.006) and presence of BRAF mutation (OR: 2.20; P =.040) were associated with an increased risk of developing symptomatic RN; the use of concurrent over nonconcurrent therapy was not associated with an increased risk (OR: 1.06; P =.877). There were 20 grade 3 toxic events reported, and no grade 4 events reported. One patient experienced a grade 5 intracranial hemorrhage. The median overall survival was 36.1 and 19.8 months for the concurrent and nonconcurrent groups (log-rank P =.051), respectively.

CONCLUSION

Concurrent administration of ICIs and SRS are not associated with an increased risk of RN. Tumors harboring BRAF mutation, or perhaps prior exposure to targeted agents, may increase this risk. Radiosurgical optimization to maintain V12 < 10 cm 3 is a potential strategy to reduce the risk of RN.

Characterization of the immune microenvironment in brain metastases from different solid tumors

Background

Brain metastases are one of the most common intracranial neoplasms. Increasing evidence have indicated that systemic immunotherapy may provide long‐term benefits for brain metastases. Herein, we presented the results of an immune oncology panel RNA sequencing platform for patients with brain metastases from different primary sites.

Methods

We investigated 25 samples of human brain metastases from lung cancer (n = 12), breast cancer (n = 6), and colorectal cancer (n = 7). Besides, 13 paired samples of adjacent noncancerous brain tissue (10 from patients with lung cancer and 3 from patients with breast cancer) were collected as controls. By comparing the brain metastases and paired samples of adjacent noncancerous brain tissue from 13 patients, we detected three upregulated and six downregulated genes, representing the malignant properties of cancer cells and increased immune infiltration in the microenvironment. Next, we profiled the immune‐related genes in brain metastases from three primary cancer types.

Results

A group of genes were significantly overexpressed in the microenvironment of brain metastases from lung cancer, covering the checkpoint pathways, lymphocyte infiltration, and TCR‐coexpression. Especially, immune checkpoint molecules, PD‐L1, PD‐L2, and IDO1 were expressed at higher levels in brain metastases from lung cancer than those from the other two cancer types.

Conclusions

This study presents an immune landscape of brain metastases from different cancer types. With high RNA expression levels of PD‐1/PD‐L1 axis and immune infiltration in brain metastases, it would be worthwhile to explore the efficacy of immune checkpoint blockade for lung cancer patients with intracranial metastases.

The effect of timing of stereotactic radiosurgery treatment of melanoma brain metastases treated with ipilimumab

OBJECTIVE

Melanoma represents the third most common cause of CNS metastases. Immunotherapy has evolved as a treatment option for patients with Stage IV melanoma. Stereotactic radiosurgery (SRS) also elicits an immune response within the brain and may interact with immunotherapy. The authors report on a cohort of patients treated for brain metastases with immunotherapy and evaluate the effect of SRS timing on the intracranial response.

METHODS

All consecutively treated melanoma patients receiving ipilimumab and SRS for treatment of brain metastases at the University of Virginia between 2009 and 2014 were included in this retrospective analysis; data from 46 patients harboring 232 brain metastases were reviewed. The median duration of clinical follow-up was 7.9 months (range 3–42.6 months). The median age of the patients was 63 years (range 24.3–83.6 years). Thirty-two patients received SRS before or during ipilimumab cycles (Group A), whereas 14 patients received SRS after ipilimumab treatment (Group B). Radiographic and clinical responses were assessed at approximately 3-month intervals after SRS.

RESULTS

The 2 cohorts were comparable in pertinent baseline characteristics with the exception of SRS timing relative to ipilimumab. Local recurrence–free duration (LRFD) was significantly longer in Group A (median 19.6 months, range 1.1–34.7 months) than in Group B patients (median 3 months, range 0.4–20.4 months) (p = 0.002). Post-SRS perilesional edema was more significant in Group A.

CONCLUSIONS

The effect of SRS and ipilimumab on LRFD seems greater when SRS is performed before or during ipilimumab treatments. The timing of immunotherapy and SRS may affect LRFD and postradiosurgical edema. The interactions between immunotherapy and SRS warrant further investigation so as to optimize the therapeutic benefits and mitigate the risks associated with multimodality, targeted therapy.

Intracranial Tumor Cell Migration and the Development of Multiple Brain Metastases in Malignant Melanoma

INTRODUCTION

A majority of patients with melanoma brain metastases develop multiple lesions, and these patients show particularly poor prognosis. To develop improved treatment strategies, detailed insights into the biology of melanoma brain metastases, and particularly the development of multiple lesions, are needed. The purpose of this preclinical investigation was to study melanoma cell migration within the brain after cell injection into a well-defined intracerebral site.

METHODS

A-07, D-12, R-18, and U-25 human melanoma cells transfected with green fluorescent protein were injected stereotactically into the right cerebral hemisphere of nude mice. Moribund mice were killed and autopsied, and the brain was evaluated by fluorescence imaging or histological examination.

RESULTS

Intracerebral inoculation of melanoma cells produced multiple lesions involving all regions of the brain, suggesting that the cells were able to migrate over substantial distances within the brain. Multiple modes of transport were identified, and all transport modes were observed in all four melanoma lines. Thus, the melanoma cells were passively transported via the flow of cerebrospinal fluid in the meninges and ventricles, they migrated actively along leptomeningeal and brain parenchymal blood vessels, and they migrated actively along the surfaces separating different brain compartments.

CONCLUSION

Migration of melanoma cells after initial arrest, extravasation, and growth at a single location within the brain may contribute significantly to the development of multiple melanoma brain metastases.

Intertumor heterogeneity in vascularity and invasiveness of artificial melanoma brain metastases

Background

Patients diagnosed with melanoma brain metastases have few treatment options and poor prognosis, and improved treatment strategies for these patients require detailed understanding of the underlying pathobiology. In this investigation we studied the vascularity and invasiveness of artificial brain metastases established from four human melanoma cell lines.

Methods

A-07, D-12, R-18, and U-25 cells transfected with GFP were injected intracerebrally and intra-arterially in nude mice. Moribund mice were killed and autopsied, and the brain was evaluated by fluorescence imaging or by histological examination. Expression and secretion of factors involved in angiogenesis and invasion were assessed by quantitative PCR, ELISA, and immunohistochemistry.

Results

The melanoma cells grew preferentially in the meninges and ventricles after intracerebral and intra-arterial injection. Intertumor heterogeneity in the aggressiveness of meningeal tumors reflected differences in angiogenic activity and expression of vascular endothelial growth factor A (VEGF-A) and interleukin 8 (IL-8). In contrast, growth and invasion of the brain parenchyma relied primarily on vascular co-option. The cell lines showed different patterns of invasion from meninges to the scull and from meninges to the brain parenchyma, and these differences were associated with differences in expression of the matrix metalloproteinases MMP-2 and MMP-9. Furthermore, the melanoma cells produced multiple brain lesions after intracerebral implantation by using the meningeal linings of the brain as transport routes.

Conclusions

The melanoma cell lines showed different growth patterns in the brain, and these differences were associated with differences in expression of the angiogenic factors VEGF-A and IL-8 and the matrix metalloproteinases MMP-2 and MMP-9.

Stereotactic radiosurgery and immunotherapy for metastatic spinal melanoma

The management of metastatic spinal melanoma involves maximizing local control, preventing recurrence, and minimizing treatment-associated toxicity and spinal cord damage. Additionally, therapeutic measures should promote mechanical stability, facilitate rehabilitation, and promote quality of life. These objectives prove difficult to achieve given melanoma's elusive nature, radioresistant and chemoresistant histology, vascular character, and tendency for rapid and early metastasis. Different therapeutic modalities exist for metastatic spinal melanoma treatment, including resection (definitive, debulking, or stabilization procedures), stereotactic radiosurgery, and immunotherapeutic techniques, but no single treatment modality has proven fully effective. The authors present a conceptual overview and critique of these techniques, assessing their effectiveness, separately and combined, in the treatment of metastatic spinal melanoma. They provide an up-to-date guide for multidisciplinary treatment strategies. Protocols that incorporate specific, goal-defined surgery, immunotherapy, and stereotactic radiosurgery would be beneficial in efforts to maximize local control and minimize toxicity.

Blinded by the light: why the treatment of metastatic melanoma has created a new paradigm for the management of cancer

Until recently, treatment for metastatic melanoma was characterised by a limited availability of treatment options that offer objective survival benefit. Cytotoxic agents fundamentally lack the ability to achieve disease control and cytokine therapy with interleukin-2 has an unacceptably high - for the use across all patient cohorts - rate of toxicities. The validation of braf as an oncogene driving melanoma tumorigenesis, as well as the discovery of the role of CTLA-4 receptor in the evasion of anticancer immune response by melanoma, has revolutionised our treatment options against a disease with dismal prognosis. Quick implementation of translational discoveries brought about BRAF/MEK inhibition in clinic, while at the same time, wider experience with CTLA-4 blockade enabled clinicians to manage previously fatal immune-related toxicities with greater confidence. The suitability for clinical use of other oncogenic drivers such as NRAS and c-kit is currently being tested whilst the PD-1/PD-L1/PD-L2 axis has emerged as a new immunotherapy target with exciting early phase results. The recent exponential progress in treatment of melanoma has set an example of translational medicine and the current review aims to explain why, as well as suggesting new goals for the future.

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.

Phenotyping of human melanoma cells reveals a unique composition of receptor targets and a subpopulation co-expressing ErbB4, EPO-R and NGF-R

Malignant melanoma is a life-threatening skin cancer increasingly diagnosed in the western world. In advanced disease the prognosis is grave. Growth and metastasis formation in melanomas are regulated by a network of cytokines, cytokine-receptors, and adhesion molecules. However, little is known about surface antigens and target expression profiles in human melanomas. We examined the cell surface antigen profile of human skin melanoma cells by multicolor flow cytometry, and compared their phenotype with 4 melanoma cell lines (A375, 607B, Mel-Juso, SK-Mel28). Melanoma cells were defined as CD45-/CD31- cells co-expressing one or more melanoma-related antigens (CD63, CD146, CD166). In most patients, melanoma cells exhibited ErbB3/Her3, CD44/Pgp-1, ICAM-1/CD54 and IGF-1-R/CD221, but did not express CD20, ErbB2/Her2, KIT/CD117, AC133/CD133 or MDR-1/CD243. Melanoma cell lines were found to display a similar phenotype. In most patients, a distinct subpopulation of melanoma cells (4-40%) expressed the erythropoietin receptor (EPO-R) and ErbB4 together with PD-1 and NGF-R/CD271. Both the EPO-R+ and EPO-R- subpopulations produced melanoma lesions in NOD/SCID IL-2Rgamma(null) (NSG) mice in first and secondary recipients. Normal skin melanocytes did not express ErbB4 or EPO-R, but expressed a functional KIT receptor (CD117) as well as NGF-R, ErbB3/Her3, IGF-1-R and CD44. In conclusion, melanoma cells display a unique composition of surface target antigens and cytokine receptors. Malignant transformation of melanomas is accompanied by loss of KIT and acquisition of EPO-R and ErbB4, both of which are co-expressed with NGF-R and PD-1 in distinct subfractions of melanoma cells. However, expression of EPO-R/ErbB4/PD-1 is not indicative of a selective melanoma-initiating potential.

B7-H3 contributes to the metastatic capacity of melanoma cells by modulation of known metastasis-associated genes

B7-H3, an immunoregulatory protein, is known to play a role in tumor progression. In many cancer types, observed correlations between high B7-H3 expression and poor prognosis have been attributed to involvement in antitumor immunity. However, here we demonstrate a nonimmunological alternative function of B7-H3 in cancer metastasis. Since advanced malignant melanoma is a disease with a poor survival rate and a broad pattern of metastasis, we used this disease as a model in our studies. We found that shRNA silencing of B7-H3 reduced the in vitro migratory potential and matrigel invasiveness of MDA-MB-435 and FEMX-I melanoma cells. In an experimental metastasis model in vivo, B7-H3 silencing of MDA-MB-435 cells resulted in reduced metastatic capacity and significantly increased the median symptom-free survival of nude mice (147 vs. 65 days, p < 0.001) and rats (53 vs. 42 days, p = 0.025) injected with MDA-MB-435 cells. Furthermore, a smaller fraction of mice had microscopically detectable metastases compared to control animals, and the pattern of metastases was slightly different between the two groups but with the brain as the predominant organ. Immunohistochemistry on samples from two melanoma patients showed strong B7-H3 staining in both a primary tumor and metastases. Notably, the metastasis-associated proteins, matrix metalloproteinase (MMP)-2, signal transducer and activator of transcription 3 (Stat3), and the level of secreted interleukin-8 (IL-8) were reduced in the B7-H3 knock-down cell variants, whereas tissue inhibitor of metalloproteinase (TIMP)-1 and-2 levels were increased. Taken together, our findings indicate a novel role for B7-H3 in the regulation of the metastatic capacity of melanoma cells and it might be a potential therapeutic target for anti-metastasis therapy.

Brain metastases as preventive and therapeutic targets

The incidence of metastasis to the brain is apparently rising in cancer patients and threatens to limit the gains that have been made by new systemic treatments. The brain is considered a 'sanctuary site' as the blood-tumour barrier limits the ability of drugs to enter and kill tumour cells. Translational research examining metastasis to the brain needs to be multi-disciplinary, marrying advanced chemistry, blood-brain barrier pharmacokinetics, neurocognitive testing and radiation biology with metastasis biology, to develop and implement new clinical trial designs. Advances in the chemoprevention of brain metastases, the validation of tumour radiation sensitizers and the amelioration of cognitive deficits caused by whole-brain radiation therapy are discussed.

Update on immunologic therapy with anti-CTLA-4 antibodies in melanoma: identification of clinical and biological response patterns, immune-related adverse events, and their management

Immune-modifying monoclonal antibodies may induce or enhance the natural immune response against tumor cells. The complex interaction between antigen-presenting cells and T lymphocytes as an immune response is strongly affected by anti-CD152 (cytotoxic T-lymphocyte antigen-4, CTLA-4)-antibodies. However, specific CTLA-4 antibodies can block the CTLA-4 receptor and thus induce an unrestrained T-cell activation. To this stage, treatment of patients with metastatic melanoma with the CTLA-4 antibodies ipilimumab and tremelimumab has only been investigated within clinical trials. The results of a phase III trial in patients with advanced disease treated with ipilimumab alone or in combination with a peptide vaccination (gp100) recently presented at the 2010 annual meeting of the Ameircan Society of Clinical Oncology (ASCO) made groundbreaking news as ipilimumab was demonstrated to be the first drug in melanoma treatment to show a significant prolongation of survival time. Patients undergoing treatment with CTLA-4 antibodies may experience immune-related phenomena and adverse events (irAEs) that differ greatly from the well-known adverse events of cytotoxic drugs and which are due to the CTLA-4 antibodies' specific mode of action. This review gives a condensed overview on the mechanisms of action, an update on clinical data of the two CTLA-4 antibodies, ipilimumab and tremelimumab, and detailed recommendations for adverse event management strategies.

Quantitative expression profiling of G-protein-coupled receptors (GPCRs) in metastatic melanoma: the constitutively active orphan GPCR GPR18 as novel drug target

G-protein-coupled receptors (GPCRs) have been implicated in the tumorigenesis and metastasis of human cancers and are considered amongst the most desirable targets for drug development. Utilizing a robust quantitative PCR array, we quantified expression of 94 human GPCRs, including 75 orphan GPCRs and 19 chemokine receptors, and 36 chemokine ligands, in 40 melanoma metastases from different individuals and benign nevi. Inter-metastatic site comparison revealed that orphan GPR174 and CCL28 are statistically significantly overexpressed in subcutaneous metastases, while P2RY5 is overexpressed in brain metastases. Comparison between metastases (all three metastatic sites) and benign nevi revealed that 16 genes, including six orphan receptors (GPR18, GPR34, GPR119, GPR160, GPR183 and P2RY10) and chemokine receptors CCR5, CXCR4, and CXCR6, were statistically significantly differentially expressed. Subsequent functional experiments in yeast and melanoma cells indicate that GPR18, the most abundantly overexpressed orphan GPCR in all melanoma metastases, is constitutively active and inhibits apoptosis, indicating an important role for GPR18 in tumor cell survival. GPR18 and five other orphan GPCRs with yet unknown biological function may be considered potential novel anticancer targets in metastatic melanoma.

Novel therapeutics for the treatment of metastatic melanoma

Metastatic malignant melanoma is an incurable disease with a median survival of 8.5 months and a probability of surviving 5 years after the diagnosis of less than 5%. To date, no systemic therapy has meaningfully changed these survival end points. Currently, in the USA the FDA has approved three agents for the treatment of metastatic melanoma: hydroxyurea, dacarbazine and interleukin-2. None of these have demonstrated a meaningfully prolonged survival of patients with metastatic melanoma. Therefore, a number of innovative therapeutic strategies have been pursued to improve outcomes, including immune therapy, tyrosine kinase inhibitors and angiogenesis inhibitors. Herein, we review some of the recent advances in novel therapeutic developments for the treatment of metastatic melanoma.