Tumor-intrinsic CDC42BPB confers resistance to anti-PD-1 immune checkpoint blockade in breast cancer.

Immune checkpoint blockade has been used to treat breast cancer, but the clinical responses remain relatively poor. We have used the CRISPR-Cas9 kinome knockout library consisting of 763 kinase genes to identify tumor-intrinsic kinases conferring resistance to anti-PD-1 immune checkpoint blockade. We have identified the CDC42BPB kinase as a potential target to overcome the resistance to anti-PD-1 immune checkpoint blockade immunotherapy. We found that CDC42BPB is highly expressed in breast cancer patients who are non-responsive to immunotherapy. Furthermore, a small-molecule pharmacological inhibitor, BDP5290, which targets CDC42BPB, synergized with anti-PD-1 and enhanced tumor cell killing by promoting T cell proliferation in both in vitro and in vivo assays. Moreover, anti-PD-1-resistant breast cancer cells showed higher expression of CDC42BPB, and its inhibition rendered the resistant cells more susceptible to T cell killing in the presence of anti-PD-1. We also found that CDC42BPB phosphorylated AURKA, which in turn upregulated PD-L1 through cMYC. Our results have revealed a robust link between tumor-intrinsic kinase and immunotherapy resistance and have provided a rationale for a unique combination therapy of CDC42BPB inhibition and anti-PD-1 immunotherapy for breast cancer.

Treatment Options for Brain Metastases.

OPINION STATEMENT: Therapies for brain metastasis continue to evolve as the life expectancies for patients have continued to prolong. Novel advances include the use of improved technology for radiation delivery, surgical guidance, and response assessment, along with systemic therapies that can pass through the blood brain barrier. With increasing complexity of treatments and the increased need for salvage treatments, multi-disciplinary management has become significantly more important.

Long term survivors of stereotactic radiosurgery for brain metastases: do distant brain failures reach a plateau and what factors are associated with a brain metastasis velocity of zero?

PURPOSE: Life expectancy continues to increase for patients with brain metastases treated with stereotactic radiosurgery (SRS). The present study sought to retrospectively analyze brain metastasis patients who have survived 2 years or more, and assess for what factors may predict for a final brain metastasis velocity (BMV) of zero. METHODS: This was a single-institution retrospective study of 300 patients treated with SRS from 2001 to 2019 for brain metastases who survived greater than 2 years after first SRS. Final BMV is calculated by summing all metastases through the observed time divided by the total time in years. A BMV of zero is defined as at least 2 years of imaging follow-up without distant brain failure (DBF). RESULTS: Median age at first SRS is 61 (IQR: 53, 70). Kaplan-Meier estimated median overall survival is 4.9 years and time to DBF is 1.5 years (95% CI 1.2, 2.0). Twenty-eight (9.3%) patients underwent subsequent WBRT. One hundred and one (33.7%) patients never had any further brain metastases (BMV = 0) at a median follow-up time of 3.3 years. Median BMV is 0.4 (IQR: 0, 1.4). Distant brain failures reach a plateau at 4 years where the cumulative incidence of DBF is 82%. 70% of first time DBFs have occurred by 2 years. Factors significantly associated with a BMV of zero include fewer brain metastases at first SRS (HR 1.1; p = 0.0004) and Caucasian race (HR 1.5; p = 0.03). CONCLUSION: Approximately one third of brain metastasis patients who live beyond 2 years after initial SRS have a BMV of zero. DBFs appear to reach a plateau at 4 years. Factors significantly associated with a BMV of zero include Caucasian race and having had a single brain metastasis at first SRS.

Local control outcomes for combination of stereotactic radiosurgery and immunotherapy for non-small cell lung cancer brain metastases.

BACKGROUND: Previous series have demonstrated CNS activity for immune checkpoint inhibitors, yet no prior data exists regarding whether this activity can improve outcomes of stereotactic radiosurgery. METHODS: In this single institution retrospective series, the clinical outcomes of 80 consecutive lung cancer patients treated with concurrent immune checkpoint inhibitors and stereotactic radiosurgery were compared to 235 in the historical control cohort in which patients were treated prior to immune checkpoint inhibition being standard upfront therapy. Overall survival was estimated using the Kaplan Meier method. Cumulative incidence of local progression was estimated using a competing risk model. RESULTS: Median overall survival time was improved in patients receiving upfront immunotherapy compared to the historical control group (40 months vs 8 months, p < 0.001). Factors affected overall survival include concurrent immunotherapy (HR 0.23, p < 0.0001) and KPS (HR 0.97, p = 0.0001). Cumulative incidence of local failure in the historical control group was 10% at 1 year, compared to 1.1% at 1 year in the concurrent immunotherapy group (p = 0.025). Factors affected local control included use of concurrent immunotherapy (HR 0.09, p = 0.012), and lowest margin dose delivered to a metastasis (HR 0.8, p = 0.0018). CONCLUSION: Local control and overall survival were both improved in patients receiving concurrent immune checkpoint inhibitors with radiosurgery compared to historical controls. While these data remain to be validated, they suggest that brain metastasis patients may benefit from concurrent use of immunotherapy with SRS.

Impact of brain metastasis velocity on neurologic death for brain metastasis patients experiencing distant brain failure after initial stereotactic radiosurgery.

PURPOSE: Patients with high rates of developing new brain metastases have an increased likelihood of dying of neurologic death. It is unclear, however, whether this risk is affected by treatment choice following failure of primary stereotactic radiosurgery (SRS). METHODS: From July 2000 to March 2017, 440 patients with brain metastasis were treated with SRS and progressed to have a distant brain failure (DBF). Eighty-seven patients were treated within the immunotherapy era. Brain metastasis velocity (BMV) was calculated for each patient. In general, the institutional philosophy for use of salvage SRS vs whole brain radiotherapy (WBRT) was to postpone the use of WBRT for as long as possible and to treat with salvage SRS when feasible. No further treatment was reserved for patients with poor life expectancy and who were not expected to benefit from salvage treatment. RESULTS: Two hundred and eighty-five patients were treated with repeat SRS, 91 patients were treated with salvage WBRT, and 64 patients received no salvage radiation therapy. One-year cumulative incidence of neurologic death after salvage SRS vs WBRT was 15% vs 23% for the low- (p = 0.06), 30% vs 37% for the intermediate- (p < 0.01), and 31% vs 48% (p < 0.01) for the high-BMV group. Salvage WBRT was associated with increased incidence of neurologic death on multivariate analysis (HR 1.64, 95% CI 1.13-2.39, p = 0.01) when compared to repeat SRS. One-year cumulative incidence of neurologic death for patients treated within the immunotherapy era was 9%, 38%, and 38% for low-, intermediate-, and high-BMV groups, respectively (p = 0.01). CONCLUSION: Intermediate and high risk BMV groups are predictive of neurologic death. The association between BMV and neurologic death remains strong for patients treated within the immunotherapy era.

Favorable outcome of patients with lung adenocarcinoma harboring POLE mutations and expressing high PD-L1.

Mutations in polymerase ε (POLE) confer favorable prognosis and outcomes in various cancer types, but their role in non-small cell lung cancer (NSCLC) is unknown. Utilizing the data of 513 patients with adenocarcinoma (LUAD) and 497 patients with squamous cell carcinoma (LUSC) from The Cancer Genome Atlas (TCGA) cohort, we tested the prognostic value of POLE mutations and programmed cell death ligand 1 (PD-L1) expression in the two main subtypes of NSCLC. POLE mutation is a favorable biomarker for the improved overall survival (OS) of the LUSC patients (P = 0.033, 28 mutant vs. 469 wildtype patients), but not that of the LUAD patients (P = 0.12, 31 mutant vs. 482 wildtype patients). POLE-mutant LUAD patients with high expression of PD-L1 (Mut-High, n = 6) exhibited improved OS (P = 0.024) when compared to POLE-mutant patients with low PD-L1 expression (Mut-Low, n = 24) and other patients without POLE mutation (n = 476). This benefit was not due to the high content of the tumor infiltrating lymphocytes. Instead, the antitumor immune response was activated in Mut-High patients so that these patients were likely responding more effectively to immuno-oncology (IO) treatments; whereas genes involved with metabolic pathways were enriched in Mut-Low group, which may cause the decreased OS of these patients. Our study sheds light on the molecular basis of NSCLC and adds to our understanding of responses to chemotherapy and IO therapy.

Surgical resection and postoperative radiosurgery versus staged radiosurgery for large brain metastases.

PURPOSE: The purpose of this study was to retrospectively evaluate the new treatment paradigm of staged stereotactic radiosurgery (SRS) for the treatment of large brain metastases (BM) compared to the standard of surgical resection followed by SRS. METHODS: We evaluated 78 patients with large BM treated 2012-2017 with surgical resection and postoperative SRS (surgery + SRS) or staged SRS separated by 1 month. Overall survival (OS) was estimated using the Kaplan Meier method and compared across groups using the log-rank test. Cumulative incidence of neurologic death and local and distant brain failure (LF, DBF) were estimated using competing risk methodology. RESULTS: Forty patients were treated with surgery + SRS and 38 patients were treated with staged SRS. Median follow-up was 23.2 months (95% CI 20.5-39.3). Median OS was 13.2 months for staged SRS compared to surgery + SRS 9.7 months (p = 0.53). Cumulative incidence of neurologic death at 1 year was 23% after surgery + SRS, 27% after staged SRS (p = 0.69); cumulative incidence of LF at 1 year was 6% and 8% (p = 0.65) and 1-year DBF was 59% and 21% (p ≤ 0.01). Overall rates of leptomeningeal failure and radiation necrosis were similar between the groups (p = 0.63 and p = 1.0). CONCLUSIONS: Though surgery and postoperative SRS is the standard, staged SRS represents an attractive treatment paradigm for treating large BM without sacrificing LC or survival, and potentially decreases DBF. Prospective studies are needed to validate these findings.

Initial brain metastasis velocity: does the rate at which cancers first seed the brain affect outcomes?

PURPOSE/OBJECTIVE(S): Brain metastasis velocity (BMV) is a metric that describes the rate of development of new brain metastases (BM) after initial stereotactic radiosurgery (SRS). A limitation in the application of BMV is it cannot be applied until time of first BM failure after SRS. We developed initial BM velocity (iBMV), a new metric that accounts for the number of BM at first SRS and the time since initial cancer diagnosis. MATERIALS/METHODS: We reviewed patients with BM treated at our institution with upfront SRS without WBRT. iBMV was calculated as the number of BM at initial SRS divided by time (years) from initial cancer diagnosis to first SRS. We performed a linear regression to correlate BMV as a continuous variable and with low, intermediate, and high BMV risk groups. Kaplan-Meier estimation of OS was calculated from time of first SRS to death. iBMV was not calculated for patients who presented with BM at initial cancer diagnosis. RESULTS: 994 patients were treated with upfront SRS without WBRT between 2000 and 2017. Median OS was 8.5 mos. 595 (60%) patients developed BM after cancer diagnosis and median time to first SRS from time of initial diagnosis was 2.2 years. Median iBMV was 0.79 BM/year. iBMV correlated with BMV (ß = 1.57 p = 0.021) and independently predicted for mortality [Cox proportional hazard ratio (HR) 1.11, p = 0.036] after accounting for histology, number of initial brain metastases (HR 1.03, p = 0.32), time from cancer diagnosis to SRS (HR 0.98, p = 0.157) in a multivariate model. CONCLUSION: iBMV correlates with BMV and OS. With further validation, iBMV could serve as a metric to risk stratify patients for WBRT or SRS at time of first BM presentation.

Protocol to Improve Genotyping of Non-Small-Cell Lung Cancer Diagnosed Using EBUS-TBNA.

OBJECTIVES: Targeted therapies for non-small-cell lung cancers (NSCLCs) are based on the presence of driver mutations such as epidermal growth factor receptor (EGFR) and the echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) translocation. Endobronchial ultrasound-guided-transbronchial needle aspiration (EBUS-TBNA) is a first-line modality for diagnosing and staging NSCLC. A quality improvement protocol maximizing tissue acquisition for molecular analysis has not been previously described. METHODS: We instituted a standardized protocol designed from a multidisciplinary meeting of the pulmonology, oncology, and pathology departments for the acquisition and on-site processing of samples obtained through EBUS-TBNA to improve the yield for genetic analysis of EGFR and ALK testing. RESULTS: Preprotocol there were 50 NSCLCs (29 adenocarcinomas) and postprotocol there were 109 NSCLCs (52 adenocarcinomas). A statistically significant increase in yield for molecular analysis was seen in both EGFR (36% preprotocol and 80% postprotocol, P < 0.01) and ALK (41% preprotocol and 80% postprotocol, P < 0.01). There was no difference in complications preprotocol and postprotocol. CONCLUSIONS: Implementation of a standardized protocol with EBUS-TBNA was associated with an increase in adequacy for molecular genetic analysis in NSCLC.

Prediction of new brain metastases after radiosurgery: validation and analysis of performance of a multi-institutional nomogram.

Stereotactic radiosurgery (SRS) without whole brain radiotherapy (WBRT) for brain metastases can avoid WBRT toxicities, but with risk of subsequent distant brain failure (DBF). Sole use of number of metastases to triage patients may be an unrefined method. Data on 1354 patients treated with SRS monotherapy from 2000 to 2013 for new brain metastases was collected across eight academic centers. The cohort was divided into training and validation datasets and a prognostic model was developed for time to DBF. We then evaluated the discrimination and calibration of the model within the validation dataset, and confirmed its performance with an independent contemporary cohort. Number of metastases (≥8, HR 3.53 p = 0.0001), minimum margin dose (HR 1.07 p = 0.0033), and melanoma histology (HR 1.45, p = 0.0187) were associated with DBF. A prognostic index derived from the training dataset exhibited ability to discriminate patients' DBF risk within the validation dataset (c-index = 0.631) and Heller's explained relative risk (HERR) = 0.173 (SE = 0.048). Absolute number of metastases was evaluated for its ability to predict DBF in the derivation and validation datasets, and was inferior to the nomogram. A nomogram high-risk threshold yielding a 2.1-fold increased need for early WBRT was identified. Nomogram values also correlated to number of brain metastases at time of failure (r = 0.38, p < 0.0001). We present a multi-institutionally validated prognostic model and nomogram to predict risk of DBF and guide risk-stratification of patients who are appropriate candidates for radiosurgery versus upfront WBRT.

Negative Predictive Value of Granulomas on EBUS-TBNA in Suspected Extrathoracic Malignancy.

PURPOSE: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a well-established diagnostic tool for lung cancer, sarcoidosis, and suspected metastatic extrathoracic malignancy. EBUS-TBNA carries a high diagnostic yield, but its negative predictive value (NPV) requires further clarification. METHODS: We reviewed EBUS-TBNA at our cancer center from 2008 to 2015. We identified negative diagnostic samples for adenopathy suspected to represent metastatic disease from extrathoracic malignancy. RESULTS: We reviewed 529 EBUS-TBNAs. Ninety patients underwent EBUS-TBNA sampling of the hilum and/or mediastinum (121 nodes, 14 masses) for suspected extrathoracic malignancy. Thirty-seven patients had negative samples (lymph node, granulomas or non-diagnostic specimens). The overall NPV was 98 %. Granulomas (11 patients, 25 nodes) seen on histology had a 100 % NPV, including those that were FDG-PET (fluorodeoxyglucose positron emission tomography) avid (n = 14 nodes). CONCLUSION: Negative EBUS-TBNA in patients with extrathoracic malignancy and suspected secondary hilar or mediastinal metastases can infer a high NPV especially if granulomas are seen on histology. Larger prospective investigations are needed to confirm the high NPV of EBUS-TBNA with granulomas in extrathoracic malignancies.

Delayed Imaging Changes 18 Months or Longer After Stereotactic Radiosurgery for Brain Metastases: Necrosis or Progression.

OBJECTIVE: Imaging changes after stereotactic radiosurgery (SRS) can occur for years after treatment, although the available data on the incidence of tumor progression and adverse radiation effects (ARE) are generally limited to the first 2 years after treatment. METHODS: A single-institution retrospective review was conducted of patients who had >18 months of imaging follow-up available. Patients who had ≥1 metastatic brain lesions treated with Gamma Knife SRS were assessed for the time to radiographic progression. Those with progression ≥18 months after the initial treatment were included in the present study. The lesions that progressed were characterized as either ARE or tumor progression based on the tissue diagnosis or imaging characteristics over time. RESULTS: The cumulative incidence of delayed imaging radiographic progression was 35% at 5 years after the initial SRS. The cumulative incidence curves of the time to radiographic progression for lesions determined to be ARE and lesions determined to be tumor progression were not significantly different statistically. The cumulative incidence of delayed ARE and delayed tumor progression was 17% and 16% at 5 years, respectively. Multivariate analysis indicated that the number of metastatic brain lesions present at the initial SRS was the only factor associated with late radiographic progression. CONCLUSIONS: The timing of late radiographic progression does not differ between ARE and tumor progression. The number of metastatic brain lesions at the initial SRS is a risk factor for late radiographic progression.

Brain metastases from renal cell carcinoma: Effects of novel systemic agents on brain metastasis outcomes.

OBJECTIVE: The objective of this study was to examine survival outcomes in 136 patients with renal cell carcinoma with metastases to the brain who were treated with radiation combined with immunotherapy or tyrosine kinase inhibitor compared to those who were treated with radiation therapy alone. METHODS: The Wake Forest Gamma Knife prospective database was searched for all patients with renal cell carcinoma brain metastases. Outcome measurements included overall survival, determined via the Kaplan-Meier Method, and cumulative incidence of local and distant failure, determined using the Fine Gray competing risks analysis with death as a competing risk for the 136 patients included. RESULTS: Overall survival for the entire population at 6 months, 12 months, and 24 months was 67%, 47% and 30%, respectively. For the TKI (non-immunotherapy-treated) population (n = 37), overall survival was 75%, 61%, and 40% at 6 months, 12 months, and 24 months, respectively. For the immunotherapy-treated population (n = 35), overall survival was 85%, 64%, and 50% at 6 months, 12 months, and 24 months, respectively. Overall survival was significantly increased for patients who received radiation with either immunotherapy or TKI (p < 0.0001). CONCLUSION: Prior series of patients with brain metastases of multiple histologies have demonstrated an improvement in the local efficacy of stereotactic radiosurgery when combined with systemic agents. We found that patients treated with targeted agents and patients treated with immunotherapy demonstrated a trend towards improvement over patients treated in the era prior to the advent of either classes of novel therapies.

Mutations Associated With High-Grade irAEs in NSCLC Patients Receiving Immunotherapies.

OBJECTIVES: Compared to low-grade irAEs, high-grade irAEs are more often dose-limiting and can alter the long-term treatment options for a patient. Predicting the incidence of high-grade irAEs would help with treatment selection and therapeutic drug monitoring. MATERIALS AND METHODS: We performed a retrospective study of 430 stage III and IV patients with non-small cell lung cancer (NSCLC) who received an immune checkpoint inhibitor (ICI), either with or without chemotherapy, at a single comprehensive cancer center from 2015 to 2022. The study team retrieved sequencing data and complete clinical information, including detailed irAEs medical records. Fisher's exact test was used to determine the association between mutations and the presence or absence of high-grade irAEs. Patients were analyzed separately based on tumor subtypes and sequencing platforms. RESULTS: High-grade and low-grade irAEs occurred in 15.2% and 46.2% of patients, respectively. Respiratory and gastrointestinal irAEs were the 2 most common irAEs. The distribution of patients with or without irAEs was similar between ICI and ICI+chemotherapy-treated patients. By analyzing the mutation data, we identified 5 genes (MYC, TEK, FANCA, FAM123B, and MET) with mutations that were correlated with an increased risk of high-grade irAEs. For the adenocarcinoma subtype, mutations in TEK, MYC, FGF19, RET, and MET were associated with high-grade irAEs; while for the squamous subtype, ERBB2 mutations were associated with high-grade irAEs. CONCLUSION: This study is the first to demonstrate that specific tumor mutations correlate with the incidence of high-grade irAEs in patients with NSCLC treated with an ICI, providing molecular guidance for treatment selection and drug monitoring.

Modulation of oxidative phosphorylation and mitochondrial biogenesis by cigarette smoke influence the response to immune therapy in NSCLC patients.

The treatment regimen of non-small cell lung cancer (NSCLC) has drastically changed owing to the superior anti-cancer effects generated by the immune-checkpoint blockade (ICB). However, only a subset of patients experience benefit after receiving ICBs. Therefore, it is of paramount importance to increase the response rate by elucidating the underlying molecular mechanisms and identifying novel therapeutic targets to enhance the efficacy of IBCs in non-responders. We analyzed the progression-free survival (PFS) and overall survival (OS) of 295 NSCLC patients who received anti-PD-1 therapy by segregating them with multiple clinical factors including sex, age, race, smoking history, BMI, tumor grade and subtype. We also identified key signaling pathways and mutations that are enriched in patients with distinct responses to ICB by gene set enrichment analysis (GSEA) and mutational analyses. We found that former and current smokers have a higher response rate to anti-PD-1 treatment than non-smokers. GSEA results revealed that oxidative phosphorylation (OXPHOS) and mitochondrial related pathways are significantly enriched in both responders and smokers, suggesting a potential role of cellular metabolism in regulating immune response to ICB. We also demonstrated that all-trans retinoic acid (ATRA) which enhances mitochondrial function significantly enhanced the efficacy of anti-PD-1 treatment in vivo. Our clinical and bioinformatics based analyses revealed a connection between smoking induced metabolic switch and the response to immunotherapy, which can be the basis for developing novel combination therapies that are beneficial to never smoked NSCLC patients.

Team-Based Hospice Referrals: A Potential Quality Metric for Lung Cancer in the Immunotherapy Era.

BACKGROUND: Immune checkpoint inhibitors (ICIs) can lead to durable responses in patients with lung cancer but may delay transitions to hospice at the end of life (EOL). We aimed to test the association of continuity of care with EOL outcomes in the ICI era. METHODS: We collected retrospective data on all patients with lung cancer who started ICI treatment at a single comprehensive cancer center in the United States (1/1/14-5/1/18) and subsequently died. We defined a hospice referral as having continuity of care if placed by a provider from the patient's multidisciplinary cancer team (e.g., a medical oncologist, palliative care specialist, intensivist, and hospitalist). RESULTS: In this cohort of 143 patients, 58% had a team-based hospice referral which was associated with a lower risk of death in the hospital. The most common reason patients declined hospice at EOL was an unwillingness to discontinue cancer-directed therapy. As compared to a similar historical cohort of patients treated with chemotherapy alone (2008-2010), there was a similar rate of hospice referral (68% vs 74%) but higher rates of new systemic therapy initiated within 30 days of death (17% vs 6%, p .001) and last dose within 14 days of death (13% vs 5%, p .005). CONCLUSIONS: Future studies should test the continuity of care at EOL as a new quality metric for advanced NSCLC.

Five-year survivors from brain metastases treated with stereotactic radiosurgery: Biology, improving treatments, or just plain luck?

Background: Improvements in therapies have led to an increasing number of long-term survivors of brain metastases. The present series compares a population of 5-year survivors of brain metastases to a generalized brain metastases population to assess for factors attributable to long-term survival. Methods: A single institution retrospective review was performed to identify 5-year survivors of brain metastases who received stereotactic radiosurgery (SRS). A historical control population of 737 patients with brain metastases was used to assess similarities and differences between the long-term survivor population and the general population treated with SRS. Results: A total of 98 patients with brain metastases were found to have survived over 60 months. No differences between long-term survivors and controls were identified with regards to the age at first SRS (P = .19), primary cancer distribution (P = .80), and the number of metastases at first SRS (P = .90). Cumulative incidence of neurologic death at 6, 8 and 10 years for the long-term survivor cohort was 4.8%, 16%, and 16% respectively. In the historical controls, cumulative incidence of neurologic death reached a plateau at 40% after 4.9 years. A significant difference in the distribution of burden of disease at the time of the first SRS was found between the 5-year survivors and the control (P = .0049). 58% of 5-year survivors showed no evidence of clinical disease at the last follow-up. Conclusion: Five-year survivors of brain metastases represent a diverse histologic population, suggesting a small population of oligometastatic and indolent cancers exist for each cancer type.

Single-cell sequencing reveals the landscape of the human brain metastatic microenvironment.

Brain metastases is the most common intracranial tumor and account for approximately 20% of all systematic cancer cases. It is a leading cause of death in advanced-stage cancer, resulting in a five-year overall survival rate below 10%. Therefore, there is a critical need to identify effective biomarkers that can support frequent surveillance and promote efficient drug guidance in brain metastasis. Recently, the remarkable breakthroughs in single-cell RNA-sequencing (scRNA-seq) technology have advanced our insights into the tumor microenvironment (TME) at single-cell resolution, which offers the potential to unravel the metastasis-related cellular crosstalk and provides the potential for improving therapeutic effects mediated by multifaceted cellular interactions within TME. In this study, we have applied scRNA-seq and profiled 10,896 cells collected from five brain tumor tissue samples originating from breast and lung cancers. Our analysis reveals the presence of various intratumoral components, including tumor cells, fibroblasts, myeloid cells, stromal cells expressing neural stem cell markers, as well as minor populations of oligodendrocytes and T cells. Interestingly, distinct cellular compositions are observed across different samples, indicating the influence of diverse cellular interactions on the infiltration patterns within the TME. Importantly, we identify tumor-associated fibroblasts in both our in-house dataset and external scRNA-seq datasets. These fibroblasts exhibit high expression of type I collagen genes, dominate cell-cell interactions within the TME via the type I collagen signaling axis, and facilitate the remodeling of the TME to a collagen-I-rich extracellular matrix similar to the original TME at primary sites. Additionally, we observe M1 activation in native microglial cells and infiltrated macrophages, which may contribute to a proinflammatory TME and the upregulation of collagen type I expression in fibroblasts. Furthermore, tumor cell-specific receptors exhibit a significant association with patient survival in both brain metastasis and native glioblastoma cases. Taken together, our comprehensive analyses identify type I collagen-secreting tumor-associated fibroblasts as key mediators in metastatic brain tumors and uncover tumor receptors that are potentially associated with patient survival. These discoveries provide potential biomarkers for effective therapeutic targets and intervention strategies.

c-Met Mediated Cytokine Network Promotes Brain Metastasis of Breast Cancer by Remodeling Neutrophil Activities.

The brain is one of the most common metastatic sites among breast cancer patients, especially in those who have Her2-positive or triple-negative tumors. The brain microenvironment has been considered immune privileged, and the exact mechanisms of how immune cells in the brain microenvironment contribute to brain metastasis remain elusive. In this study, we found that neutrophils are recruited and influenced by c-Met high brain metastatic cells in the metastatic sites, and depletion of neutrophils significantly suppressed brain metastasis in animal models. Overexpression of c-Met in tumor cells enhances the secretion of a group of cytokines, including CXCL1/2, G-CSF, and GM-CSF, which play critical roles in neutrophil attraction, granulopoiesis, and homeostasis. Meanwhile, our transcriptomic analysis demonstrated that conditioned media from c-Met high cells significantly induced the secretion of lipocalin 2 (LCN2) from neutrophils, which in turn promotes the self-renewal of cancer stem cells. Our study unveiled the molecular and pathogenic mechanisms of how crosstalk between innate immune cells and tumor cells facilitates tumor progression in the brain, which provides novel therapeutic targets for treating brain metastasis.

Collagen deposition within brain metastases is associated with leptomeningeal failure after cavity-directed radiosurgery.

Background: Leptomeningeal failure (LMF) represents a devastating progression of disease following resection of brain metastases (BrM). We sought to identify a biomarker at time of BrM resection that predicts for LMF using mass spectrometry-based proteomic analysis of resected BrM and to translate this finding with histochemical assays. Methods: We retrospectively reviewed 39 patients with proteomic data available from resected BrM. We performed an unsupervised analysis with false discovery rate adjustment (FDR) to compare proteomic signature of BrM from patients that developed LMF versus those that did not. Based on proteomic analysis, we applied trichrome stain to a total of 55 patients who specifically underwent resection and adjuvant radiosurgery. We used competing risks regression to assess predictors of LMF. Results: Of 39 patients with proteomic data, FDR revealed type I collagen-alpha-1 (COL1A1, P = .045) was associated with LMF. The degree of trichrome stain in each block correlated with COL1A1 expression (ß = 1.849, P = .001). In a cohort of 55 patients, a higher degree of trichrome staining was associated with an increased hazard of LMF in resected BrM (Hazard Ratio 1.58, 95% CI 1.11-2.26, P = .01). Conclusion: The degree of trichrome staining correlated with COL1A1 and portended a higher risk of LMF in patients with resected brain metastases treated with adjuvant radiosurgery. Collagen deposition and degree of fibrosis may be able to serve as a biomarker for LMF.