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Melanoma-derived brain metastases (MBM) represent an unmet clinical need because central nervous system progression is frequently an end stage of the disease. Immune checkpoint inhibitors (ICI) provide a clinical opportunity against MBM; however, the MBM tumor microenvironment (TME) has not been fully elucidated in the context of ICI. To dissect unique elements of the MBM TME and correlates of MBM response to ICI, we collected 32 fresh MBM and performed single-cell RNA sequencing of the MBM TME and T-cell receptor clonotyping on T cells from MBM and matched blood and extracranial lesions. We observed myeloid phenotypic heterogeneity in the MBM TME, most notably multiple distinct neutrophil states, including an IL8-expressing population that correlated with malignant cell epithelial-to-mesenchymal transition. In addition, we observed significant relationships between intracranial T-cell phenotypes and the distribution of T-cell clonotypes intracranially and peripherally. We found that the phenotype, clonotype, and overall number of MBM-infiltrating T cells were associated with response to ICI, suggesting that ICI-responsive MBMs interact with peripheral blood in a manner similar to extracranial lesions. These data identify unique features of the MBM TME that may represent potential targets to improve clinical outcomes for patients with MBM.

Supplementary Figure from Microenvironmental Landscape of Human Melanoma Brain Metastases in Response to Immune Checkpoint Inhibition

Supplementary Data from Microenvironmental Landscape of Human Melanoma Brain Metastases in Response to Immune Checkpoint Inhibition

Melanoma-derived brain metastases (MBM) represent an unmet clinical need because central nervous system progression is frequently an end stage of the disease. Immune checkpoint inhibitors (ICI) provide a clinical opportunity against MBM; however, the MBM tumor microenvironment (TME) has not been fully elucidated in the context of ICI. To dissect unique elements of the MBM TME and correlates of MBM response to ICI, we collected 32 fresh MBM and performed single-cell RNA sequencing of the MBM TME and T-cell receptor clonotyping on T cells from MBM and matched blood and extracranial lesions. We observed myeloid phenotypic heterogeneity in the MBM TME, most notably multiple distinct neutrophil states, including an IL8-expressing population that correlated with malignant cell epithelial-to-mesenchymal transition. In addition, we observed significant relationships between intracranial T-cell phenotypes and the distribution of T-cell clonotypes intracranially and peripherally. We found that the phenotype, clonotype, and overall number of MBM-infiltrating T cells were associated with response to ICI, suggesting that ICI-responsive MBMs interact with peripheral blood in a manner similar to extracranial lesions. These data identify unique features of the MBM TME that may represent potential targets to improve clinical outcomes for patients with MBM.

A 48-year-old woman presented to her primary care physician (PCP) with right eye vision loss. She began noticing changes in her vision earlier in the year while at work. Over the ensuing months, her vision progressively declined such that she was no longer able to read with the right eye but could appreciate movement. Her past medical history included iron deficiency anemia for which she received iron infusions, depression, and anxiety. She denied fevers, sweats, chills, anorexia, weight loss, cough, shortness of breath, swollen lymph nodes, or any other systemic symptoms. She had traveled to Mexico, South America, the Caribbean, and Europe. She never had penetrating trauma to the head, although she did have a concussion as a toddler. She had spent time in Arizona and in the northern United States/southern Canada. She has several pets including dogs, small mammals, and birds; none was ill. She had no history of diabetes, immunosuppression, or HIV.

Melanoma-derived brain metastases (MBM) represent an unmet clinical need due to central nervous system (CNS) progression as a frequent, end-stage site of disease. Immune checkpoint inhibition (ICI) represents a clinical opportunity against MBM; however, the MBM tumor microenvironment (TME) has not been fully elucidated in the context of ICI. To dissect unique MBM-TME elements and correlates of MBM-ICI response, we collected 32 fresh MBM and performed single cell RNA sequencing of the MBM-TME and T cell receptor clonotyping on T cells from MBM and matched blood and extracranial lesions. We observed myeloid phenotypic heterogeneity, most notably multiple distinct neutrophil states including an IL-8 expressing population that correlated with malignant cell epithelial-to-mesenchymal transition. Additionally, we observe significant relationships between intracranial T cell phenotypes and the distribution of T cell clonotypes intracranially and peripherally. We found that the phenotype, clonotype, and overall number of MBM-infiltrating T cells were associated with response to ICI, suggesting that ICI-responsive MBMs interact with peripheral blood in a manner similar to extracranial lesions. These data demonstrate unique features of the MBM-TME, which may represent potential targets to improve clinical outcomes for patients with MBM.

Chimeric antigen receptor (CAR) T-cell therapy is a highly effective new treatment for relapsed and refractory hematological cancers but is associated with the novel treatment-limiting toxicities of cytokine release syndrome and neurotoxicity. Neurotoxicity, now more commonly referred to as immune effector cell-associated neurotoxicity syndrome (ICANS), is a clinical and neuropsychiatric syndrome that can occur in the days to weeks following CAR T-cell and other T-cell-engaging therapies. While the clinical characteristics of ICANS have been well described, its pathophysiology is poorly understood, and best treatment and preventive strategies remain elusive. Clinical trial experience and animal models suggest a central role for endothelial cell dysfunction, myeloid cells, blood-brain barrier disruption, and elevated central nervous system cytokine levels in the development of ICANS. Here we discuss ICANS incidence, clinical features, risk factors, biomarkers, pathophysiology, and grading and management.