Leptomeningeal Metastasis In Patients Research Articles

Individual survival prediction model for patients with leptomeningeal metastasis.

Survival prediction for patients with leptomeningeal metastasis (LM) is crucial for making proper management plans and counseling patients. Prognostic models in this patient domain have been limited, and existing models often include predictors that are not available in resource-limited settings. Our aim was to develop a practical, individualized survival prediction model for patients diagnosed with LM. We collected a retrospective cohort of patients diagnosed with LM from cerebrospinal fluid at Chiang Mai University Hospital from January 2015 to July 2021. Nine candidate predictors included male gender, age>60years, presence of extracranial involvement, types of primary cancer, the time between primary cancer and LM diagnosis, presence of cerebral symptoms, cranial symptoms, spinal symptoms, and abnormal CSF profiles. Flexible parametric survival analysis was used to develop the survival prognostic model for predicting survival at 3, 6, and 12months after diagnosis. The model was evaluated for discrimination and calibration. 161 patients with 133 events were included. The derived individual survival prediction model for patients with LM, or the LMsurv model, consists of three final predictors: types of primary cancer, presence of cerebral symptoms, and presence of spinal symptoms. The model showed acceptable discrimination (Harrell's C-statistics: 0.72; 95% confidence interval 0.68-0.76) and was well calibrated at 3, 6, and 12months. The LMsurv model, incorporating three practical predictors, demonstrated acceptable discrimination and calibration for predicting survival in LM patients. This model could serve as an assisting tool during clinical decision-making. External validation is suggested to confirm the generalizability of the model.

OS10.4.A CXCL1 MEDIATES LEPTOMENINGEAL METASTASIS GROWTH

Abstract BACKGROUND Leptomeningeal metastasis (LM) is a fatal neurological complication of cancer characterized by the entry of metastatic cancer cells originated from solid or hematologic tumors into the cerebrospinal fluid (CSF)-filled leptomeningeal compartment encasing the brain and the spinal cord. LM occurs in 5-20% in patients with solid tumors, especially those with breast cancer, lung cancer, melanoma. Untreated LM patients succumb within 4-6 weeks after diagnosis, or 2-5 months when they are treated with the current available therapies. To date, the only efficacious life-prolonging intervention was the application of proton craniospinal irradiation (pCSI) as demonstrated in the recent clinical trial, NCT04343573, with an average overall survival of 9 months. While a cohort of pCSI-treated patients survived over 18 months (responders), another cohort did not respond to pCSI and succumbed to the disease within 3 months post-treatment (non-responders). In this project, we aimed to characterize the molecular basis of pCSI response to turn the non-responders into responders. MATERIAL AND METHODS We performed proteomic analyses on serially collected CSF from LM patients at baseline (before pCSI), and multiple time points post-treatment. We further established syngeneic mouse models of LM-CSI to define the molecular basis of pCSI resistance. RESULTS We found that pCSI resulted in a significant drop in the levels of the chemokine CXCL1, a CXC-motif chemokine with elevated baseline levels after the onset of LM. Patients with significantly higher CSF CXCL1 levels prior to pCSI had worse central nervous system (CNS) progression-free survival. Using our preclinical LM mouse models, we found that both the cancer and host cells, namely macrophages, choroid plexus epithelial cells, and leptomeningeal fibroblasts, were a source of CXCL1. Genetic manipulation of Cxcl1expression in cancer cells or host revealed that the CXCL1 produced by the cancer cells was an essential factor for their growth in the leptomeninges. Moreover, we found that a subset of cancer cells expressed a receptor for CXCL1 - CXCR2 - and transcriptomic profiling of this rare population revealed an enrichment in pathways associated with cell cycle progression. Finally, intrathecally delivered CXCR2 antagonist hampered the LM growth. CONCLUSION Our results indicate that CXCL1/CXCR2 signaling axis regulates LM growth and suggests interruption of this signaling axis as a possible actionable therapeutic intervention to halt LM progression.

Real-world use of a CSF circulating tumor cell assay in the diagnosis and management of leptomeningeal metastasis.

2029 Background: The diagnosis of leptomeningeal metastasis (LM) can be challenging due to variability in clinical symptoms, radiographic, and cerebrospinal fluid (CSF) findings. The National Comprehensive Cancer Network (NCCN) guidelines recommend assessment of circulating tumor DNA (ctDNA) to increase sensitivity of tumor cell detection and assess the response to treatment. We hypothesize that the real-world use of an assay for the direct detection and enumeration of circulating tumor cells (CTCs) in the CSF is clinically useful for accurate diagnosis of LM, particularly in an early stage of disease. Methods: We report a series of 55 patients treated at our institution with a cancer diagnosis and either neurological symptoms or radiographic findings that suggested LM. All patients underwent a lumbar puncture, assessment for CSF CTCs, and conventional hospital-based cytology testing between 6/1/2020 and 8/1/2023. Survival data cutoff was 12/31/2023. Patient outcomes are reported. Results: 55 patients were tested, and 30 patients were found to be positive for CTCs and diagnosed with LM. Only 10 patients were concurrently positive for CTCs and cytology at our institution, whereas 20 patients with positive CTCs had a negative or ambiguous cytology. No patients with a negative CTC result (25 patients) were subsequently diagnosed with LM, whereas 4 patients with a positive CTC result remained without progressive neurological symptoms. 5 patients diagnosed with LM were alive at the time of data cutoff. The histologic breakdown for LM was: breast (11), non-small cell lung cancer (NSCLC) (16), gastrointestinal (GI) (3). Median overall survival (OS) was longer in patients with a positive CTC and negative cytology result compared to patients with concurrent positive CTC and cytology (172 vs. 63 days, p = 0.06). Median OS was also longer in breast cancer LM compared to NSCLC LM (235 vs. 63 days, p = 0.008). Most patients diagnosed with LM received therapies including Ommaya reservoir placement, intrathecal chemotherapy, and/or radiation. Conclusions: The use of a CSF circulating tumor cell assay aided the diagnosis of LM and led to timely initiation of treatment. A negative result of the CTC assay was associated with ruling out LM. Diagnosis of LM with the CTC assay and negative cytology was associated with longer survival, possibly due to earlier treatment initiation, and not solely a lead time bias. Breast cancer LM patients had improved survival compared to NSCLC and GI cancer patients, possibly due to more effective treatment options.

Different genetic profiles contribute to worse overall survival in patients with leptomeningeal metastases of non-small-cell lung cancer.

To assess the genetic characteristics of central nervous system (CNS) metastases from non-small-cell lung cancer (NSCLC), we gathered the genetic profiles of brain metastases (BM) and leptomeningeal metastases (LM). Our objective was to identify genetic factors contributing to poorer overall survival (OS) in NSCLC patients with LM. This study included 25 consecutive patients with BM and 52 patients with LM from Guangdong Sanjiu Brain Hospital. All participants underwent 168-target panel sequencing. Among the 25 patients with BM, TP53 was the most frequently mutated gene (44%), followed by driver genes such as EGFR and BRAF (40% and 20%, respectively). In patients with BM, EGFR_amp and CDK4 were also frequently mutated, with rates of 20% and 16%, respectively. The genetic landscape of patients with LM differed, with the top mutated genes being EGFR, TP53, EGFR_amp, CDKN2A, CCNE1, CDK4, PMS2, and PIK3CA, with mutation rates of 77%, 69%, 31%, 29%, 13%, 13%, 13%, and 12%, respectively. In our study, patients with LM exhibited significantly worse OS compared to those with BM (p = 0.029). The mutation rates of TP53, EGFR_amp, and CDKN2A varied between patients with LM and those with BM, at 69.23% vs. 44%, 30.77% vs. 20%, and 28.85% vs. 12%, respectively. Further exploration revealed that patients with BM with TP53 mutations had a shorter OS than patients without TP53 mutations (p = 0.014). Similarly, patients with LM and TP53 mutations presented with worse OS than those without TP53 mutations (p = 0.0067). LM patients with CDKN2A deletions had worse OS than those without CDKN2A deletions (p = 0.037). Additionally, patients with EGFR_amp had a shorter OS than those without EGFR_amp (p = 0.044). Patients with LM exhibited significantly worse OS than those with BM. Gene signatures, such as TP53, EGFR_amp, and CDKN2A, may account for shorter outcomes in patients with LM.

Proton Craniospinal Irradiation for Treatment of Leptomeningeal Metastasis in Patients with Solid Malignancy: The MD Anderson Cancer Center Experience (S27.006)

Proton Craniospinal Irradiation for Treatment of Leptomeningeal Metastasis in Patients with Solid Malignancy: The MD Anderson Cancer Center Experience (S27.006)

Extracellular Vesicles from Cerebrospinal Fluid of Leptomeningeal Metastasis Patients Deliver MiR-21 and Induce Methotrexate Resistance in Lung Cancer Cells.

Leptomeningeal metastasis (LM) is a common and fatal complication of advanced non-small cell lung cancer (NSCLC) caused by the spread of malignant cells to the leptomeninges and cerebrospinal fluid (CSF). While intra-CSF methotrexate (MTX) chemotherapy can improve prognosis, eventual MTX resistance deters continued chemotherapy. Recent studies have shown that increased miRNA-21 (miR-21) expression in the CSF of patients with LM after intraventricular MTX-chemotherapy is associated with poor overall survival; however, the molecular mechanisms underlying this resistance are poorly understood. Here, we confirm, in 36 patients with NSCLC-LM, that elevated miR-21 expression prior to treatment correlates with poor prognosis. MiR-21 overexpression or sponging results in a corresponding increase or decrease in MTX resistance, demonstrating that cellular miR-21 expression correlates with drug resistance. MiR-21-monitoring sensor and fluorescent extracellular vesicle (EV) staining revealed that EV-mediated delivery of miR-21 could modulate MTX resistance. Moreover, EVs isolated from the CSF of LM patients containing miR-21 could enhance the cell proliferation and MTX resistance of recipient cells. These results indicate that miR-21 can be transferred from cell-to-cell via EVs and potentially modulate MTX sensitivity, suggesting that miR-21 in CSF EVs may be a prognostic and therapeutic target for overcoming MTX resistance in patients with NSCLC-LM.

Diagnostic value of cerebrospinal fluid human epididymis protein 4 for leptomeningeal metastasis in lung adenocarcinoma.

The diagnosis of lung adenocarcinoma (LUAD) leptomeningeal metastasis (LM) remains a clinical challenge. Human epididymis protein 4 (HE4) functions as a novel tumor biomarker for cancers. This study aimed to assess the diagnostic value of cerebrospinal fluid (CSF) HE4, and combined with CEACAM6, for LUAD LM. The CSF HE4 protein level was measured in two independent cohorts by electrochemiluminescence. Test cohort included 58 LUAD LM patients, 22 LUAD patients without LM (Wiot-LM), and 68 normal controls. Validation cohort enrolled 50 LUAD LM patients and 40 normal controls, in parallel with Wiot-LM patients without brain metastases (19 Wiot-LM/BrM patients) or with BrM (26 BrM patients). The CSF level of CEA, CA125, CA153, CA199, CA724, NSE and ProGRP of these samples was measured by electrochemiluminescence, whereas the CSF CEACAM6 level was detected by enzyme-linked immunosorbent assay (ELISA). In addition, the serum level of these biomarkers was detected by same method as CSF. The level of HE4 or CEACAM6 in CSF samples from LUAD LM patients was significantly higher than those from normal controls and Wiot-LM patients. The HE4 or CEACAM6 level in CSF was higher than that in serum of LM patient. The CSF HE4 or CEACAM6 level for distinguished LM from Wiot-LM showed good performance by receiver-operating characteristic analysis. The better discriminative power for LM was achieved when HE4 was combined with CEACAM6. In addition, the CSF HE4 and CEACAM6 level showed little or no difference between Wiot-LM/BrM and BrM patients, the BrM would not significantly influence the HE4 or CEACAM6 level in CSF. The diagnostic power of CSF CA125, CA153, CA199, CA724, NSE and ProGRP for LUAD LM were not ideal. The combination with HE4 and CEACAM6 has the promising application for the diagnosis of LUAD LM.

Intrathecal chemotherapy for leptomeningeal metastases in patients with breast cancer

To evaluate the effectiveness of ITT in patients with leptomeningeal metastases in breast cancer. Twenty-five patients with breast cancer and leptomeningeal metastases underwent intrathecal administration of methotrexate between 2016 and 2022. Intrathecal chemotherapy was administered through lumbar puncture. We performed an intensive course (intrathecal methotrexate 15 mg 2 times a week for 1 month (8 injections), then intrathecal methotrexate 15 mg 1 time a week (4 injections), and then 15 mg 1 time a month until progression or unacceptable toxicity). The median duration of ITT was 2.5 months. Complete neurological responses were observed in 3 out of 25 (12%) patients, partial neurological response - in 15 out of 25 (60%) patients, progression of neurological symptoms - in 7 (28%) patients. The number of complete cytological responses was observed in 6 out of 25 (24%) patients. The median overall survival after ITT was 6.7 months. Effectiveness of ITT is confirmed by higher quality of life (72% of patients), complete cytological responses (24%) and improvement in neuroimaging data. This is an important criterion for severe patients with limited treatment options. First-stage ITT before whole-brain irradiation is preferable, as this approach increases overall survival by 3 months. Undoubtedly, ITT is a treatment option that can be used in routine clinical practice for lesions of brain and spinal cord sheaths.

Cerebrospinal fluid circulating tumor DNA contributes to the detection and characterization of leptomeningeal metastasis in non-small cell lung cancer.

Cerebrospinal fluid (CSF) has revealed the unique genetic characteristics of leptomeningeal metastasis (LM) from non-small cell lung cancer (NSCLC). However, the research in this area is still very limited. Patients with LM from NSCLC (n = 80) were retrospectively analyzed. Circulating tumor DNA (ctDNA) in CSF was tested by next-generation sequencing (NGS), with paired extracranial tissue or plasma samples included for comparison. An independent non-LM cohort (n = 100) was also analyzed for comparative purposes. Clinical outcomes were compared with Kaplan-Meier log-rank test and Cox proportional hazards methodologies. An overwhelming 93.8% of patients carried druggable mutations in NSCLC LM, with EGFR (78.8%) being the most prevalent. Notably, 4 patients who tested negative for driver genes in extracranial samples surprisingly showed EGFR mutations in their CSF and subsequently benefited from targeted therapy. There was a clear difference in genetic profiles between CSF and extracranial samples, with CSF showing more driver gene detections, increased Copy Number Variations (CNVs), and varied resistance mechanisms among individuals. Abnormalities in cell-cycle regulatory molecules were highly enriched in LM (50.9% vs 31.0%, p = 0.017), and CDKN2A/2B deletions were identified as an independent poor prognostic factor for LM patients, with a significant reduction in median OS (p = 0.013), supported by multivariate analysis (HR 2.63, 95% CI 1.32-5.26, p = 0.006). CSF-based ctDNA analysis is crucial for detecting and characterizing genetic alterations in NSCLC LM. The distinct genetic profiles in CSF and extracranial tissues emphasize the need for personalized treatment approaches.

EP12.02-08 Frequency and Outcomes of Leptomeningeal Metastases in Patients with Fusion-Positive Lung Cancers

EP12.02-08 Frequency and Outcomes of Leptomeningeal Metastases in Patients with Fusion-Positive Lung Cancers

Cerebrospinal fluid circulating tumour DNA genotyping and survival analysis in lung adenocarcinoma with leptomeningeal metastases

PurposeThe prognosis of patients with leptomeningeal metastasis (LM) remains poor. Circulating tumour DNA (ctDNA) has been proven to be abundantly present in cerebrospinal fluid (CSF); hence, its clinical implication as a biomarker needs to be further verified.MethodsWe conducted a retrospective study of 35 lung adenocarcinoma (LUAD) patients with LM, and matched CSF and plasma samples were collected from all patients. All paired samples underwent next-generation sequencing (NGS) of 139 lung cancer-associated genes. The clinical characteristics and genetic profiling of LM were analysed in association with survival prognosis.ResultsLM showed genetic heterogeneity, in which CSF had a higher detection rate of ctDNA (P = 0.003), a higher median mutation count (P < 0.0001), a higher frequency of driver mutations (P < 0.01), and more copy number variation (CNV) alterations (P < 0.001) than plasma. The mutation frequencies of the EGFR, TP53, CDKN2A, MYC and CDKN2B genes were easier to detect in CSF than in LUAD tissue (P < 0.05), possibly reflecting the underlying mechanism of LM metastasis. CSF ctDNA is helpful for analysing the mechanism of EGFR-TKI resistance. In cohort 1, which comprised patients who received 1/2 EGFR-TKIs before the diagnosis of LM, TP53 and CDKN2A were the most common EGFR-independent resistant mutations. In cohort 2, comprising those who progressed after osimertinib and developed LM, 7 patients (43.75%) had EGFR CNV detected in CSF but not plasma. Furthermore, patient characteristics and various genes were included for interactive survival analysis. Patients with EGFR-mutated LUAD (P = 0.042) had a higher median OS, and CSF ctDNA mutation with TERT (P = 0.013) indicated a lower median OS. Last, we reported an LM case in which CSF ctDNA dynamic changes were well correlated with clinical treatment.ConclusionsCSF ctDNA could provide a more comprehensive genetic landscape of LM, indicating the potential metastasis-related and EGFR-TKI resistance mechanisms of LM patients. In addition, genotyping of CSF combined with clinical outcomes can predict the prognosis of LUAD patients with LM.

Clinical characteristics and their influences on the survival of leptomeningeal metastasis derived from lung adenocarcinoma harboring epithelial growth factor receptor mutation

Objective: To analyze the clinical characteristics of leptomeningeal metastasis (LM) patients from epithelial growth factor receptor (EGFR)-mutated lung adenocarcinoma, and their impacts on the survival of the patients. Methods: From July 2018 to July 2022, the clinicopathological data of 81 patients diagnosed as EGFR-mutated lung adenocarcinoma LM by cytopathology who admitted to the Department of Oncology of Xiangya Hospital of Central South University were retrospectively analyzed, including 33 males and 48 females. The age ranged from 31 to 76 years, with a median age of 54 years. All the 81 patients were followed up, with a median follow-up of 21.0 months (95%CI: 12.5 to 29.5 months). The Kaplan Meier method was used to draw survival curve. Cox proportional hazards regression model was used to analyze the impact of the factors on the survival of patients. Results: Among the 81 patients, the interval between the initial diagnosis of lung cancer and the pathological diagnosis of LM in cerebrospinal fluid (CSF) was 0-108 months, with a median interval of 14 months. Fifty-two patients (64.2%) used the third-generation epithelial growth factor receptor tyrosine kinase inhibitor (EGFR-TKIs), while 17 patients (21.0%) used EGFR-TKIs in combination with other drugs, and 12 patients (14.8%) were treated with best supportive care (BSC). Sixty patients (74.1%) had a Kanofsky performance status (KPS) score of less than 60 points, and 71 patients (87.7%) had brain parenchymal metastasis and/or spinal metastasis. Twenty-two patients (27.2%) used pemetrexed through intrathecal CSF, and 17 patients (21.0%) used pemetrexed through the Ommaya sac to the CSF of the ventricle. The incidence of adverse event related to the administration of pemetrexed through CSF was 64.1% (25/39), mainly manifested as myelosuppression, including 22 patients of leukocyte reduction, 25 patients of hemoglobin reduction, and 14 patients of platelet reduction. The median post-leptomeningeal metastasis overall survival (pLM-OS) in 81 patients was 11.0 (95%CI: 7.7-14.3) months. KPS score≥60 points (HR=0.407, 95%CI: 0.170-0.973, P=0.043), CSF cytology negative after treatment (vs persistent positive, HR=0.351, 95%CI: 0.155-0.792, P=0.012), intraventricular administration of pemetrexed (vs non intraventricular administration of pemetrexed, HR=0.319, 95%CI: 0.137-0.745, P=0.008) and the treatment with third-generation EGFR-TKIs after LM (vs EGFR-TKIs in combination with other drugs, HR=0.486, 95%CI: 0.237-0.998, P=0.049) were a factor affecting pLM-OS of patients. Conclusions: Brain parenchyma, or/and spine are the most sites where the LM patients concurrently metastasize. KPS score≥60 points and CSF cytology negative after treatment, intraventricular administration of pemetrexed and the treatment with third-generation EGFR-TKIs are indictors affecting pLM-OS of the patients.

New strategies for the treatment of breast cancer with leptomeningeal metastasis.

Leptomeningeal metastasis is a complication of metastatic breast cancer that has a rising incidence likely due to the increased availability of novel systemic therapies, which have improved survival with better extracranial disease control but with limited intracranial efficacy. A poor prognosis of less than 6 months has historically been associated with leptomeningeal metastasis and it is often an exclusion factor for enrollment in clinical trials. There are limited evidence-based data supporting use of therapeutics in leptomeningeal metastasis patients and recommendations are largely derived from retrospective reports and small prospective studies. However, in recent years, there has been a surge in effective modern therapeutics with promising intracranial activity. The study aims to review the most recent updates in the management of leptomeningeal metastasis in breast cancer. We discuss the effectiveness and limitations of intrathecal administration, predictive biomarkers in the cerebrospinal fluid, proton radiation therapy and promising new systemic therapies such as antibody drug conjugates. Ongoing development of clinical trials that allow inclusion of leptomeningeal metastasis are essential for establishing efficacy potential and discovering new treatment options in this population of great unmet need.

SDPS-20 THE HER2 FLIP: HER2 AMPLIFICATION OF TUMOR CELLS IN THE CEREBROSPINAL FLUID (CSF-TCS) OF PATIENTS WITH LEPTOMENINGEAL METASTASIS HAVING SOLID TUMORS; IMPLICATIONS FOR TREATING THE LM TUMOR WITH ANTI-HER2 THERAPY

Abstract INTRODUCTION Patients diagnosed with Leptomeningeal Metastasis (LM) have limited treatment options. However, they may benefit from targetable therapy. LM breast cancer patients with HER2 positive primary tumors treated with IT Trastuzumab experienced clinical benefit (Malani, 2020), and improved craniospinal PFS (Figura, 2019). HER2 amplification of the primary and metastatic tumors can be heterogeneous. Biocept’s CNSideTM is a CLIA validated Laboratory Developed Test and is used commercially at the discretion of Physicians to detect CSF tumor cells (CSF-TCs). We analyzed HER2 amplification on CSF-TCs in LM patients with breast-, upper GI cancer as well as Non-Small Cell Lung Cancer (NSCLC). METHODS CSF was collected from patients with suspected or confirmed LM having Breast Cancer (N=334 patients, N=181 evaluable), NSCLC (N=28 patients) or upper GI cancer (N=4 patients, N=2 evaluable). CSF TCs were tested for HER2 amplification by FISH using CNSide. RESULTS For the breast cancer patients, 38% (68/181) had HER2 FISH detected on CSF TCs, 60% (109/181) had a HER2 negative primary tumor of which 35% (38/109) had HER2 positive CSF-TCs. Furthermore, 8% (14/181) had an equivocal HER2 primary tumor, 21% (3/14) of which had HER2 positive CSF-TCs. For the NSCLC patients, 50% (14/28) showed HER2 amplification on the CSF-TCs. For the upper GI cancer patients, one patient had an equivocal HER2 primary tumor, and HER2 positive CSF-TCs. CONCLUSION HER2 amplification is detected on CSF-TCs of patients with LM having breast cancer, upper GI cancer or NSCLC cancer. For NSCLC patients, HER2 positivity in the LM can be associated with drug resistance. Patients who have a HER2 negative primary tumor can develop HER2 positive LM, allowing for an anti-HER2 targetable treatment. Additional studies are needed to establish the clinical utility of CNSide in the detection of HER2 on the CSF-TCs to direct treatment of anti-HER2 therapy in patients with LM.

Leptomeningeal metastasis in patients with non-small cell lung cancer after stereotactic radiosurgery for brain metastasis.

Stereotactic radiosurgery (SRS) is an effective treatment for brain metastases (BMs) in patients with non-small cell lung cancer (NSCLC). However, factors associated with the development of post-SRS leptomeningeal metastasis (LM) remain unclear. The authors analyzed the incidence and risk factors of LM development in patients with NSCLC and BMs after SRS and examined the survival outcomes and prognostic factors after LM development. This retrospective study included patients with NSCLC treated with SRS for MRI-diagnosed BM from 2002 to 2021. The authors recorded various clinical and demographic data, including age, sex, tumor histology, molecular profile of tumors, extracranial disease status, previous craniotomy, Karnofsky Performance Status, systemic treatments, tumor volume, and number of BMs. The management and survival outcomes after LM diagnosis were also recorded. LM developed in 13.7% of patients with NSCLC and BMs after SRS treatment. Large initial tumor volume and more than 5 BM lesions, but not EGFR mutation status and post-SRS treatment, were associated with LM development after SRS. Multivariate analysis revealed that chemotherapy and targeted therapy after LM were associated with better survival in patients with LM after SRS. This study is the first to evaluate the risk factors for LM in a relatively large cohort of patients with NSCLC after SRS. In patients with BMs harboring risk factors for subsequent LM, such as initial tumor volume and number of metastatic lesions, aggressive therapies with high CNS penetrating ability should be considered.

An individual patient-level meta-analysis of non–small-cell lung cancer leptomeningeal metastases treated with epidermal growth factor receptor inhibitors.

e21118 Background: Leptomeningeal metastasis (LM) is a debilitating condition associated with advanced non-small cell lung cancer (NSCLC). When driver mutations in the epidermal growth factor receptor (EGFR) are identified, targeted therapies (TT) represent an appealing therapeutic strategy. However, the efficacy of TT for LM is unknown as LM patients are routinely omitted from clinical trials. Methods: We conducted a systematic review and meta-analysis of individual patient data to evaluate the efficacy of EGFR TT in EGFR-mutant NSCLC LM in accordance with PRISMA guidelines. EGFR-TTs evaluated were erlotinib, gefitinib, icotinib, afatinib, dacomitinib, osimertinib, zorifertinib, and furmonertinib. The co-primary endpoints were progression-free survival (PFS) and overall survival (OS). To assess differences between groups, shared frailty Cox regression models were used to estimate the hazard ratio (HR), 95% confidence interval (CI) and p-value. Results: 7780 abstracts were screened, identifying 126 publications with 232 patients, corresponding to 272 lines of EGFR-TT for NSCLC LM which met inclusion criteria. The overall median PFS (mPFS) in patients receiving any EGFR-TT was 9.15 months and the median overall survival was 14.5 months. In univariable analyses, osimertinib was associated prolonged PFS compared to other EGFR-TT, (mPFS of 11 versus 8 months, HR = 0.64; 95% CI: 0.44-0.93; P = 0.02). Osimertinib was numerically associated with prolonged OS compared to other EGFR-TT (mOS 16.8 months versus 13.6 months, HR = 0.72; 95% CI 0.44-1.17, P = 0.188). In multivariable analyses, ECOG performance status &gt; 2 was independently associated with shortened PFS (mPFS 10 versus 8 months, HR = 1.54, 95% CI: 1.26-3.04; P &lt; 0.05) and OS (mOS 16.5 versus 10 months, HR = 3.33, 95% CI: 1.80-6.18; P &lt; 0.05). Conclusions: In the largest cohort of NSCLC LM treated with EGFR TT compiled to date, osimertinib is associated with marginally improved outcomes compared to other EGFR TTs. ECOG performance status is an independent predictor of prognosis in these patients. These results highlight the need for prospective studies for this difficult to treat patient population.

Baseline characteristics, hospital outcomes, and palliative care utilization in leptomeningeal disease: A nationwide analysis.

e14004 Background: Leptomeningeal metastasis (LM) is a rare but devastating manifestation of cancer metastasis. Most solid tumors are known to cause LM, but the most common etiology is breast cancer and lung cancer. The incidence of LM has been increasing due to increased survival rates secondary to the improved systemic cancer treatment. Here we aim to explore the baseline characteristics, epidemiologic differences, palliative care utilization. and hospital outcomes of LM. Methods: Nationwide Inpatient Sample (NIS) database 2016-2019 was queried to determine adult hospitalized patients with LM and relevant cancers by using ICD-10 codes. We studied the racial and socioeconomic differences, palliative care utilization, length of stay (LOS), total hospital charges (THC), and all-cause mortality in cancer patients with and without LM. Multivariate logistic regression analysis was conducted to adjust for confounders. Results: There were 15,325 admissions with LM, 20% had lung cancer (LC) and 20.4% had breast cancer (BC). The prevalence of LM was 1.9% and 0.5%, respectively, in LC and BC patients. LM patients were younger (LC 63 vs 69; BC 56 vs 64 p&lt;0.001), more likely to be non-White, and more likely to have private insurance (37% vs. 19%, p&lt;0.001). LM admissions had significantly increased LOS and higher THC compared to other cohorts. BC or LC with LM was associated with significantly increased Palliative care consult rate ( LC 31% vs 16%; BC 29% vs 10% p&lt;0.001) compared to BC and LC without LM. Palliative care use was more common in the African American race. The all-cause mortality rate in hospitalizations with LM was increased compared to cancer without LM (LC 11% vs 8.6% p=0.008 aOR 1.41; BC 12.8% vs 4.5% p&lt;0.001 aOR 3.39). The white race (OR 0.6, p&lt;0.001) and Medicare (OR 0.58 p&lt;0.001) were associated with lower odds of mortality, while the Hispanic race (OR 1.43, p=0.042) and Medicaid (OR 1.39, p=0.041) were associated with higher odds of mortality among LM hospitalizations. Conclusions: While actionable mutations and targeted therapies are developing rapidly, therapeutic options for LM remain limited, with a median survival of 4-5 months. Palliative care remains essential for a better quality of life; hence further studies should be conducted to improve the utilization of palliative care and investigate racial and economic disparities in the utilization of such.

Cerebrospinal fluid circulating tumor DNA for the detection and characterization of leptomeningeal metastasis in non-small cell lung cancer.

e21039 Background: Cerebrospinal fluid (CSF) has revealed the unique genetic characteristics of leptomeningeal metastasis (LM) from non-small cell lung cancer (NSCLC). However, the research in this area is still very limited. Methods: Patients with LM from NSCLC were retrospectively analyzed. Circulating tumor DNA (ctDNA) of CSFand pairedextracranial tissue or plasma were tested by ARMS or next-generation sequencing(NGS).Clinical outcomes were compared with Kaplan-Meier log-rank test and Coxproportional hazards methodologies. Results: We reviewed charts of 80 patients with LM treated atFujian Cancer Hospital. A total of 57 CSF and of which 30 contemporaneouslypaired extracranial samples tested by NGS were analyzed. Most interestingly, CSF ctDNA revealed EGFR mutations in 4 patients previously diagnosed as wild-type by extracranial specimens, and survival was extended by targeted therapy. In the gene map of paired samples, CSF showed more abundant cell-cycle regulatory genes and complex independent evolutionary. CDKN2A/2B CNVs-del was enriched threefold in CSF (~26.3%) with LM compared to extracranial specimens (~8.9%)in lung adenocarcinoma without LM. The median overall survival (OS) was 14.1 months [95% confidence interval (CI): 10.7–17.5 months]. Univariate analyses and multivariate Cox analyses demonstrated that patients with CDKN2A/CDKN2Bco-mutation had poor prognosis. Conclusions: CSF-based ctDNA testing contributes to the phenotypic detection and unique characterization of resistance mechanisms of LM in NSCLC. CDKN2A/2B mutation maybe a poor prognostic factor in LM patients.

Genomic profiling of cerebrospinal fluid ctDNA to characterize molecular features and monitor intracranial responses of patients with osimertinib-resistant non-small cell lung cancer with leptomeningeal metastases.

e21095 Background: Leptomeningeal metastasis (LM) indicates an unfavorable prognosis in non-small cell lung cancer (NSCLC). Due to the blood-brain barrier, plasma is not an ideal medium to evaluate osimertinib resistance mechanisms in patients with LM. This study aimed to use cerebrospinal fluid (CSF) as a source of ctDNA for characterizing molecular features and monitoring intracranial responses from patients with leptomeningeal metastases who progressed on osimertinib. Methods: From Jan 2020 to Nov 2022, 65 patients with advanced NSCLC, including 32 osimertinib-treated patients, 6 other TKI-treated patients, and 27 treatment-naïve patients, in Beijing Tiantan Hospital were enrolled in this study. CSF obtained via lumbar puncture was used for targeted sequencing and cytologic analysis. In parallel, paired plasma from 35 patients was also subjected to targeted sequencing. Results: Among 65 patients, the overall positive rate of CSF ctDNA was 77% (50/65), 94% (34/36) in patients with LM, and 55% (16/29) in patients with brain parenchymal metastases (p = 0.0002). CSF ctDNA analysis had a higher consistency with the cytologic diagnosis of LM than imaging. Among the patients cytologic diagnosed with LM, 94% (32/34) of the patients had positive CSF ctDNA analysis at the same time, while the positive diagnostic rate of imaging was only 39% (13/33). EGFR alteration was found in 97% (29/30) CSF of patients with LM who progressed on Osimertinib, including L858R (67%), exon19 deletion (17%), T790M (10%), L861Q (7%), G719X (7%) and L747X (7%). Other recurrent genes discovered in the CSF were TP53 (73%), PIK3CA (43%), ERBB2 (33%), POLE (33%), ALK (27%), BRCA2 (27%), BRAF (23%), BRCA1 (23%), RB1 (20%) and PALB (20%). In the 35 paired CSF-plasma pairs, more alterations were uniquely found in CSF than in plasma (71% vs 17%), and only 12% of alterations were shared. Serial surveillance of CSF ctDNA in 7 cases of LM patients treated with osimertinib found that the VAF of CSF ctDNA showed a highly consistent trend with the tumor cell fraction of cytology. Conclusions: For NSCLC patients with LM, liquid biopsy of CSF is more sensitive than plasma to characterize osimertinib-resistant mechanisms and guide follow-up treatment. Serial surveillance of CSF ctDNA dynamics may reflect the intracranial tumor responses, which still needs to be validated in a large sample size.

Cerebrospinal fluid exosomal microRNAs as biomarkers for diagnosing or monitoring the progression of non-small cell lung cancer with leptomeningeal metastases

ABSTRACT Non-small-cell lung cancer (NSCLC) has a terrible consequence called leptomeningeal metastases (LM). It is crucial to look for novel biomarkers because none of the known biomarkers could effectively reflect the oncogenesis, progression and therapeutic responses of LM. Exosomal miRNAs from plasma have a critical function in lung cancer, according to growing data. However, unique biomarkers of cerebrospinal fluid (CSF) are more representative for patients with LM, which have not been reported. Here, we explore the possibility of using CSF-derived exosomal microRNAs as potential biomarkers for NSCLC-LM. Nine NSCLC-LM patients who received regular intrathecal chemotherapy with permetexed were divided into a partial response (PR) group and a progressive disease (PD) group. CSF samples were taken from all patients before and after intrathecal treatment and five non-cancerous controls. Using the size exclusion chromatography (SEC) method, the exosome microRNAs were isolated and profiled. Between LM patients and controls, 56 differentially expressed genes (DEGs) were found, of which three highly elevated diagnostic biomarkers (hsa-miR-183-5p, hsa-miR-96-5p and hsa-miR-182-5p) were ruled out. The two most significant DEGs between the untreated PR group and the PD group were determined to be upregulated hsa-miR-509-3p and downregulated hsa-miR-449a, and they may serve as potential indicators of intrathecal anti-pemetrexed treatment. Hsa-miR-1-3p increased gradually with the intrathecal chemotherapy in the PR group, which might offer a new approach to screen optimal patients and estimate the efficacy. This study revealed specific CSF exosomal miRNAs profile and dynamic changes of patients with NSCLC-LM for the first time and identified several potential exosomal miRNA biomarkers in diagnosis, drug resistance and prognosis.