Abstract Introduction: Younger women with breast cancer (BC) have increased risk to develop brain metastases (BM) irrespective of the tumor subtype. We have shown that pre-menopausal levels of 17-β-Estradiol (E2) promotes BM of estrogen-unresponsive BC cells by modulating astrocyte function. Yet, microglia (the brain resident-macrophages) express estrogen-receptors (ERs), mediate the neuroprotective and homeostatic effects of E2 in the brain, and play pro and anti-tumorigenic roles through brain metastases progression. Thus, we hypothesized that E2 acts on ER+ microglia to regulate its neuroinflammatory properties and suppress anti-tumoral responses in the brain. Results: To assess how E2 modulates brain immune cells, we performed multiparametric flow cytometry across different stages of BM progression in spontaneous and experimental models of BMs. From early to late stages of BM colonization, brains of E2-treated mice showed reduced neutrophils, lymphocyte infiltration, B and CD8+ T cells compared to E2-suppressed mice. scRNAseq of immune cells from BM-bearing mice identified 6 functional microglia subclusters. The migration Mg cluster, marked by microglial homeostatic genes known to promote activation and surveillance movements, the TNF-α cluster, marked by genes associated with promotion of microglial activation, and the Interferon Mg cluster, marked by genes involved in the regulation of type I Interferons were less abundant in E2-treated mice than E2-suppressed mice. Overrepresentation analysis showed microglia from E2-treated mice enriched in translation programs, while microglia from E2-suppresed mice had a significant enrichment of immune leukocyte activation and antigen presentation processes, suggesting E2 suppresses key microglia functions as antigen-presenters and activators of T cells. To determine how microglia from E2-treated or E2-depleted mice differentially influence T cell function, we performed in vitro coculture assays to assess T cell activation, effector-associated markers, and expansion. Microglia from E2-stimulated BM bearing mice showed decreased ability to induce interferon cytotoxic function and expansion of activated T cells, supporting a pro-tumorigenic T cell immune response. Since BMs are usually treated with brain radiotherapy (RT), either as whole brain radiotherapy (WBRT) or stereotactic radiosurgery (SRS), we tested whether E2-suppression impacted radiotherapy response in experimental metastases models. E2-suppression (ovarian suppression in combination with an aromatase inhibitor) significantly increased the effectiveness of radiation in decreasing BM progression. These studies provide a novel mechanism whereby E2 promotes rapid progression of BMs and provides a rationale for the clinical -testing of endocrine therapies in the management of BMs of E2-unresponsive tumors. Citation Format: Karen L.F. Alvarez-Eraso, Maria J. Contreras-Zárate, Andrew Goodspeed, James Costello, Jenny A. Jaramillo-Gómez, Stella Koliavas, R. Alejandro Marquez-Ortiz, Morgan S. Fox, D. Ryan Ormond, Peter Kabos, Mercedes Rincon, Diana M. Cittelly. Estrogen induces a pro-tumoral phenotype shift in microglia that contributes to E2-unresponsive breast cancer brain metastasis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Brain Cancer; 2026 Mar 23-25; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2026;86(6_Suppl):Abstract nr PR007.

The central nervous system (CNS) is a common site of metastatic spread for both non-small cell and small cell lung cancer, yet the therapeutic strategies to prevent and decrease lung cancer brain metastases remain limited. Tyrosine kinase inhibitors have shown promising results in increasing the overall response in brain metastases, owing to their brain penetrance and increased effectiveness; however, their use is limited to the small group of tumors carrying specific oncogenic drivers. Among these, inhibitors with activity against neurotrophic tyrosine receptor kinases (NTRKs) are showing promising effects in reducing CNS metastases in cancers driven by gene rearrangements of these drugs' targets. However, wild-type NTRKs are susceptible to activation by their canonical ligands, which are expressed throughout the brain metastatic niche and can, in a paracrine manner, activate NTRK function in cancer cells. Here we show that NTRKs are expressed in primary tumors, brain metastases, and lung cancer cells with various driver mutations expressing wild-type NTRK2 (WT-TrkB). We demonstrate that WT-TrkB activates downstream signaling and proliferation in response to exogenous BDNF and conditioned media from reactive astrocytes known to secrete BDNF in the brain niche. Importantly, the FDA-approved NTRK inhibitor entrectinib blocked BDNF and astrocyte-induced survival pathways in multiple lung cancer cell lines, decreased their proliferation in vitro , and effectively prevented brain metastatic colonization and progression in vivo without significant effects on extracranial disease. Thus, these studies suggest that brain-dependent activation of NTRK is critical for brain metastases of WT-NTRK+ lung cancers, and therefore, NTRK inhibitors can be used to target non-fusion NTRK function to prevent or decrease brain metastases. SIGNIFICANCE:These studies demonstrate that NTRK wild-type receptors are important drivers of brain metastatic colonization and progression in different subtypes of lung cancer, independent of their driver alterations. Thus, they provide rationale to expand the use of FDA-approved NTRK inhibitors with brain penetrance for the prevention of CNS metastases.

BACKGROUND:Young age is an independent risk factor for the development of breast cancer brain metastases (BM). Prior work showed that 17β-estradiol (E2), the predominant premenopausal hormone, promotes BM of tumors intrinsically unresponsive to E2, in part through modulating estrogen receptor-alpha expressing (ERα⁺) glial cells. However, how E2 reshapes the brain tumor microenvironment (TME), particularly microglia‑mediated immunity, and its impact to BM progression remains unclear. METHODS:scRNA sequencing and multiparametric flow cytometry were used to define the impact of E2 and E2-suppression on brain immune-cell populations across different stages of BM progression using spontaneous and experimental models of BM. Depletion of microglia and T-cell co-cultures were used to study microglia's role in E2-induced BM. The effects of E2-suppression alone or in combination with whole brain radiotherapy were tested in preclinical models mimicking late-stage BM. RESULTS:E2 repressed immune surveillance and immune activation programs in microglia from early to late stages of brain metastatic progression, suppressing recruitment of effector immune cells to BM. Estrogen suppression, in turn reactivated anti-tumoral signaling in microglia and increased recruitment of effector immune cells to the brain. Microglia from E2-treated BM-bearing mice showed a reduced capacity to promote T-cell expansion, effector potential, and CD8⁺T cell-mediated tumor cell killing. Conversely, E2-suppression reactivated an effective anti-tumoral response and synergized with RT to significantly decrease BM progression. CONCLUSION:These findings reveal a previously unrecognized mechanism by which E2 accelerates BC‑BM progression through microglial immunosuppression and support evaluation of endocrine therapies as adjunct treatments for ER⁻ breast cancer brain metastases.

With the recent improvements in surgery, along with our ability to manage many pituitary tumors medically, the exact role of surgery for the treatment of functioning pituitary adenomas (PA) remains unclear. The purpose of this evidence-based clinical practice guideline was to determine the role of surgery in the treatment of functioning PA. A systematic review of the literature was performed using the National Library of Medicine/PubMed database and Embase for studies relevant to the role of surgery in the treatment of patients with functioning PA. Clinical studies evaluating the role of trans-sphenoidal surgery vs medical management, endoscopic techniques vs microsurgery, the benefit of the use of adjunct surgical techniques to patient outcome, and the role of second surgery were selected for review. The literature search yielded 7073 abstracts. Of these, 60 studies met inclusion criteria, and evidence-based guidelines were formulated on the use of surgical resection compared with medical management, the use of endoscopic techniques and/or other surgical adjunct techniques, and the benefit of reoperation for recurrent tumors compared with medical treatment and/or radiation. Class III evidence suggests a benefit to surgery over medical management for growth hormone–secreting adenomas without evidence to support a benefit to pretreatment with a somatostatin analog before surgery. Class III evidence suggests a benefit to medical management over surgery in the treatment of patients with prolactinomas at primary diagnosis. There are insufficient data to support the benefit of endoscopic surgery compared with microscopic surgery, with or without additional adjuvant surgical techniques, for extent of surgical resection, hormone remission, length of stay, or complication rate, in the treatment of functioning PA. There is a suggestion, however, that the endoscopic technique may be superior to the microscopic technique, for a shorter operative time and for extent of surgical resection and hormone remission rates for noninvasive pituitary macroadenomas. Similarly, there are insufficient data to support the use of reoperation for recurrent tumor compared with radiation and/or medical treatment.

Abstract Introduction: Younger women with breast cancer (BC) have increased risk to develop brain metastases (BM) irrespective of the tumor subtype. We have shown that pre-menopausal levels of 17-β-Estradiol (E2) promotes BM of estrogen-unresponsive BC cells by modulating astrocyte function. Yet, microglia (the brain resident-macrophages) express estrogen-receptors (ERs), mediate the neuroprotective and homeostatic effects of E2 in the brain, and play pro and anti-tumorigenic roles through brain metastases progression. Thus, we hypothesized that E2 acts on ER+ microglia to regulate its neuroinflammatory properties and suppress anti-tumoral responses in the brain. Results: To assess how E2 modulates brain immune cells, we performed multiparametric flow cytometry across different stages of BM progression in spontaneous and experimental models of BMs. From early to late stages of BM colonization, brains of E2-treated mice showed reduced neutrophils, lymphocyte infiltration, B and CD8+ T cells compared to E2-suppressed mice. scRNAseq of immune cells from BM-bearing mice identified 6 functional microglia subclusters. The migration Mg cluster, marked by microglial homeostatic genes known to promote activation and surveillance movements, the TNF-α cluster, marked by genes associated with promotion of microglial activation, and the Interferon Mg cluster, marked by genes involved in the regulation of type I Interferons were less abundant in E2-treated mice than E2-suppressed mice. Overrepresentation analysis showed microglia from E2-treated mice enriched in translation programs, while microglia from E2-suppresed mice had a significant enrichment of immune leukocyte activation and antigen presentation processes, suggesting E2 suppresses key microglia functions as antigen-presenters and activators of T cells. To determine how microglia from E2-treated or E2-depleted mice differentially influence T cell function, we performed in vitro coculture assays to assess T cell activation, effector-associated markers, and expansion. Microglia from E2-stimulated BM bearing mice showed decreased ability to induce interferon cytotoxic function and expansion of activated T cells, supporting a pro-tumorigenic T cell immune response. Since BMs are usually treated with brain radiotherapy (RT), either as whole brain radiotherapy (WBRT) or stereotactic radiosurgery (SRS), we tested whether E2-suppression impacted radiotherapy response in experimental metastases models. E2-suppression (ovarian suppression in combination with an aromatase inhibitor) significantly increased the effectiveness of radiation in decreasing BM progression. These studies provide a novel mechanism whereby E2 promotes rapid progression of BMs and provides a rationale for the clinical -testing of endocrine therapies in the management of BMs of E2-unresponsive tumors. Citation Format: Karen L.F. Alvarez-Eraso, Maria J. Contreras-Zárate, Andrew Goodspeed, James Costello, Jenny A. Jaramillo-Gómez, Stella Koliavas, R. Alejandro Marquez-Ortiz, Morgan S. Fox, D. Ryan Ormond, Peter Kabos, Mercedes Rincon, Diana M. Cittelly. Estrogen induces a pro-tumoral phenotype shift in microglia that contributes to E2-unresponsive breast cancer brain metastasis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Brain Cancer; 2026 Mar 23-25; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2026;86(6_Suppl):Abstract nr B063.

OBJECTIVE:Hydrocephalus can result from mass lesions for several reasons. Due to limited numbers of adult patients with mass lesions in studies that examine outcomes of endoscopic third ventriculostomy, success in this population is unclear. Additionally, the role of other ventriculoscopic procedures in the management of associated hydrocephalus is unclear. In this retrospective case series, the authors investigated optimal management strategies for patients with mass lesions and hydrocephalus. METHODS:A list of patients who underwent ventriculoscopic procedures or shunting procedures was compiled. Basic demographics, pathology, etiology of hydrocephalus, imaging, surgical procedures, complications, and long-term outcomes were obtained from the electronic medical record. Patients were subanalyzed in groups based on pathology, type of hydrocephalus, and initial management strategy. RESULTS:A total of 98 patients were identified. The most common pathologies causing hydrocephalus were gliomas, (n = 33, 33.67%), metastatic lesions (n = 17, 17.35%), pineal region tumors (n = 13, 13.27%), and cystic lesions (n = 13, 13.27%). Colloid cysts were excluded. Obstructive hydrocephalus was the most common cause of hydrocephalus (n = 102, 81.60%). All patients who presented with communicating hydrocephalus were treated with shunting. The long-term success of endoscopic approaches was 83.33%. Patients with gliomas and CNS lymphoma were least likely to be shunt free after endoscopic management. CONCLUSIONS:The etiology of hydrocephalus in patients with mass lesions is heterogeneous. Shunting is effective in patients with communicating hydrocephalus. Endoscopic management is successful in patients with obstructive hydrocephalus if their tumors do not have a propensity for leptomeningeal disease, such as high-grade gliomas or CNS lymphoma.

The central nervous system (CNS) is a common site of metastasis for both non-small cell and small cell lung cancer, yet the therapeutic strategies to prevent and decrease lung cancer brain metastases (BM) remain limited. Tyrosine kinase inhibitors have shown promising results in increasing overall response in BM, owing to their brain penetrance and increased effectiveness; however, their use is limited to a small group of tumors carrying specific oncogenic drivers. Among these, inhibitors targeting neurotrophic tyrosine receptor kinases (NTRK) are showing promising effects in reducing CNS metastases in cancers driven by gene rearrangements of these drugs' targets. However, wild-type NTRKs are susceptible to activation by their canonical ligands, which are expressed throughout the BM niche and can, in a paracrine manner, activate NTRK function in cancer cells. In this study, we show that NTRKs are expressed in primary tumors, BM, and lung cancer cells with various driver mutations expressing wild-type NTRK2 (WT-TrkB). We demonstrate that WT-TrkB activates downstream signaling and proliferation in response to exogenous brain-derived neurotrophic factor (BDNF) and conditioned media from reactive astrocytes known to secrete BDNF in the brain niche. Importantly, the FDA-approved NTRK inhibitor entrectinib blocked BDNF and astrocyte-induced survival pathways in multiple lung cancer cell lines, decreased their proliferation in vitro, and effectively prevented BM colonization and progression in vivo without significant effects on extracranial disease. Thus, these studies suggest that brain-dependent activation of NTRK is critical for BM of WT-NTRK+ lung cancers; therefore, NTRK inhibitors can be used to target nonfusion NTRK function to prevent or decrease BM. SIGNIFICANCE:These studies demonstrate that NTRK wild-type receptors are important drivers of brain metastatic colonization and progression in different subtypes of lung cancer, independent of their driver alterations. Thus, they provide a rationale to expand the use of FDA-approved NTRK inhibitors with brain penetrance for the prevention of CNS metastases.

BACKGROUND:The management of World Health Organization (WHO) grade II diffuse glioma is an important facet of all physicians involved in neuro-oncology. OBJECTIVE:This is an update of the evidence-based guidelines for management of WHO grade II diffuse gliomas published by the Congress of Neurological Surgeons and American Association of Neurological Surgeons in 2015. METHODS:The medical literature from January 1, 2013, through January 31, 2020, was searched to determine if information was available to update, modify, or create new recommendations related to imaging, surgical approaches, neuropathology and molecular markers, radiotherapy, chemotherapy, and management of tumor recurrence. RESULTS:The writing group used the information from the updated literature search to formulate recommendations based on this evidence and not simply built on biased consensus or expert opinion. CONCLUSION:This series of guideline documents provides an update of the information and recommendations provided in the 2015 version. It sets a benchmark as to the published information we have to support the management of this difficult disease. It also provides clues to key investigations that are necessary to move us toward effective control of WHO grade II diffuse gliomas.

Astrocytomas and oligodendrogliomas are slow-growing and treatment-sensitive IDH-mutant gliomas diagnosed at ages 30-50. Local tumor regrowth and treatment resistance is inevitable resulting in 3-10 year astrocytoma and up to >20 years oligodendroglioma survival. We sought to identify genetic changes associated with tumor evolution in response to therapy through multi-timepoint whole-genome/whole-exome sequencing of 206 IDH-mutant glioma patient samples collected through the Glioma Longitudinal Analysis (GLASS) Consortium. We validated known genomic markers of tumor progression, including hypermutation and CDKN2A homozygous deletion, and discovered novel genetic alterations that distinguish the response to treatment in astrocytomas compared to oligodendrogliomas. Point mutations in PIK3CA , PIK3R1 , and NOTCH1 were newly acquired in recurrent oligodendrogliomas and associated with increased mutation rates. Focal oncogene amplifications, together with CDKN2A homozygous deletions, were associated with an increase in recurrence-specific chromosomal imbalances in astrocytomas. Mutational signature analysis revealed additional differences and detected enrichment for the SBS11, and SBS119 mutational signatures after temozolomide treatment in both IDH-glioma subtypes, whereas astrocytomas showed increased ID8 signatures after radiotherapy. These signatures suggest that the genomes of oligodendroglioma and astrocytoma adapt to the selective pressures of tumor progression and treatment in different ways. However, in both IDH-mutant glioma subtypes we observed a convergence of acquired driver gene alterations with genome-wide changes and worse patient outcomes, signaling selection of treatment-refractory clones. By identifying new prognostic markers and delineating the genomic divergence of oligodendrogliomas and astrocytomas after diagnosis, our results suggest that different DNA damage response mechanisms are engaged following chemo- and radiation therapy.

BACKGROUND:Patients with functioning pituitary adenomas (FPA) present a diagnostic challenge with identification of microadenomas and/or invasion of the cavernous sinus. OBJECTIVE:The aim of this study was to provide evidence-based recommendations on the use of imaging to facilitate an accurate diagnosis. METHODS:PubMed and Embase were searched from the inception of the database to June 8, 2021, using search terms and search strategies to identify pertinent abstracts. These were then screened using published exclusion/inclusion criteria to identify full-text review articles. Evidence tables were constructed using data from full-text reviews, and recommendations were made. RESULTS:Of the total 8685 identified abstracts pertinent to this topic, 138 full articles met the eligibility criteria. Of these, 18 met the inclusion criteria and were included in the evidence tables. Class III evidence supported 4 Level III recommendations for adult patients with FPA. CONCLUSION:This systematic review provides evidence-based recommendations to guide providers caring for adult patients with FPA when making decisions pertinent to imaging. The Congress of Neurological Surgeons will continue to pursue timely updates and to further improve the care of patients with diagnosis.

Introduction: While glioma incidence in the US has stabilized, prognosis remains poor. One underutilized MRI modality, Diffusion Tensor Imaging (DTI), could be used to better predict postoperative glioma resection outcomes. DTI measures the structural integrity of brain white matter tracts by measuring water diffusion. We examined whether lateralized gliomas affected the structure of limbic tract bundles, and whether those changes correlated with tumor location, size, and number of tracts within the bundle. Methods: We conducted a retrospective study of 33 glioma patients who underwent preoperative DTI and examined the cingulum, fornix, and uncinate fasciculus. Using software (ITK-SNAP, DSI Studio), we obtained diffusion coefficients (fractional anisotropy (FA), mean diffusivity (MD)), tumor volume, lobe location, and tract number. With FA and MD as measures of axonal integrity, tracts of the non-tumor hemisphere(contralateral), the tumor hemisphere that is traversing the tumor (ipsilateral inclusive), and the tumor hemisphere without traversing the tumor (ipsilateral exclusive) were compared. Additionally, we correlated these hemispheric changes to tumor size, location, and FA/MD. Results: In the cingulum, FA and MD are significantly different between contralateral and ipsilateral inclusive and between ipsilateral exclusive versus ipsilateral inclusive. Similar findings were found in the uncinate fasciculus MD. FA and MD of cingulum, fornix, and uncinate fasciculus are significantly correlated with the number of tracts within the tumor hemisphere. Conclusion: Our study, one of the first to specifically examine limbic related tracts, shows that gliomas could increase white matter tracts numbers and impact structure. Localized impact on white matter integrity is in line with previous observations. These findings support DTI as a pre-op planning tool; white matter of significant limbic tracts are affected by gliomas and this change is measurable. We plan on further analyzing data to include how tumor location could affect white matter, and to incorporate patient post-op mortality and morbidity.

Table S6: Deconvolution cell proportions and probe-signature matrix S6A: Methylcibersort cell proportions S6B: Methylcibersort cell reference mixture

Supplementary Figure 3. Predictive value of IL13RA2 or EFNB1 mRNA levels in primary tumors known to metastasize to brain. Dataset contains 21 matched breast cancer primary and brain metastasis samples, reported in (https://pubmed.ncbi.nlm.nih.gov/29961873/). A. Kaplanmeier plots for IL13RA2 mRNA expression in primary tumors. B. Kaplan-Meier plots to EFNB1 mRNA in primary tumors. C. Kaplan-meier plots for primary tumors with low-IL13RA2/highEFNB1 compared to samples with high-IL13RA2/low-EFNB1. For all plots, average mRNA expression was determined for each target and expression ranked as low (below mean) or high (above mean). Survival curves comparisons were made using Log-rank (Mantel-Cox) test. p<0.05 was considered significant (italic bold). OS: overall survival; DFS: disease free survival; BMFS: brain metastasis free survival; SPBM: survival post brain metastasis.

Table S2: List of 132 pairs (ID of Initial and Recurrent samples)

Background Glioblastoma exhibits aggressive growth and poor outcomes despite treatment, and its marked variability renders therapeutic design and prognostication challenging. The Oncology Research Information Exchange Network (ORIEN) database contains complementary clinical, genomic, and transcriptomic profiling of 206 glioblastoma patients, providing opportunities to identify novel associations between molecular features and clinical outcomes. Methods Survival analyses were performed using the Logrank test, and clinical features were evaluated using Wilcoxon and chi-squared tests with q-values derived via Benjamini-Hochberg correction. Mutational analyses utilized sample-level enrichments from whole exome sequencing data, and statistical tests were performed using the one-sided Fisher Exact test with Benjamini-Hochberg correction. Transcriptomic analyses utilized a student’s t-test with Benjamini-Hochberg correction. Expression fold changes were processed with Ingenuity Pathway Analysis to determine pathway-level alterations between groups. Results Key findings include an association of MUC17, SYNE1, and TENM1 mutations with prolonged overall survival (OS); decreased OS associated with higher epithelial growth factor receptor (EGFR) mRNA expression, but not with EGFR amplification or mutation; a 14-transcript signature associated with OS > 2 years; and 2 transcripts associated with OS < 1 year. Conclusions Herein, we report the first clinical, genomic, and transcriptomic analysis of ORIEN glioblastoma cases, incorporating sample reclassification under updated 2021 diagnostic criteria. These findings create multiple avenues for further investigation and reinforce the value of multi-institutional consortia such as ORIEN in deepening our knowledge of intractable diseases such as glioblastoma.

Table S5: Treatment-related probes and samples (Related to Figure 3) S5A: List of 69 IDHmut pairs with treatment information (ID of Initial and Recurrent samples and group assignment) S5B: List of differentially methylated probes associated with treatment in IDHmut gliomas S5C: List of differentially methylated probes associated with treatment in IDHmut astrocytomas S5D: List of CpG-gene pairs (epigenetic regulation associated with treatment)

Younger women with breast cancer have increased risk of development of brain metastases (BM) irrespective of the tumor subtype. We have shown that pre-menopausal levels of 17-β-Estradiol (E2) promotes BM of estrogen receptor negative (ER¯) BC cells by inducing neuroinflammatory ER+ glial cells to secrete pro-metastatic factors critical for early brain colonization. Yet, the clinical translation of endocrine therapies (ET) to the management of BM requires a better understanding of its effectiveness at late stages of metastatic progression and its interactions with current standard of care (SOC). Using scRNAseq of brain immune cells isolated from E2 or E2-suppressed mice carrying BMs we show that pre-menopausal levels of E2 suppressed immune surveillance, activation, and IRF-7/interferon-driven anti-tumoral programs in microglia. Multiparametric flow cytometry show that E2 repressed recruitment of T, B and NK cells to the brain niche from early to late stages of BM progression and ET (ovarian suppression and aromatase inhibitors) restored recruitment of these effector immune cells to the brain. ET decreased BM progression when used in combination with brain radiotherapy (RT), but not when ET was used alone or in immunocompromised mouse models, suggesting ET-induced recruitment of interferon driven T, B and NK cells to the brain synergizes with radiotherapy to promote more effective anti-tumoral immune responses. Depletion of CD4+T, CD8+T, and NK1.1+ cells in E2-suppressed mice carrying BMs showed that anti-tumoral effects of RT and ET depend on CD4T and NK cells. Suppression of CD4+ T cells further increased the effectiveness of ET and RT and improved survival, suggesting that subsets of T cells, possibly Treg cells are critical to regulate BM antitumoral responses. While ET+RT were comparable to anti-PD-1+RT in decreasing BMs, their effects were not additive. Thus, our results suggest that FDA-approved ET synergizes with RT but not PD-1 inhibitors for treatment of BMs.

Table S1: GLASS surgery-level clinical and molecular characteristics (N=354)

Supplementary Table 1. List of shRNAs Supplementary Table 2. List of primers and sgRNAs Supplementary Table 3: List of antibodies