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

PURPOSE: 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 (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. RESULTS: 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). CONCLUSIONS: 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.

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

PURPOSE: The 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. METHODS: We 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. RESULTS: LM 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. CONCLUSIONS: CSF 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.

Prognostic impact of EGFR/ALK alterations in leptomeningeal metastasis from lung adenocarcinoma treated with whole-brain radiotherapy.

The prognosis and prognostic factors of patients receiving whole-brain radiotherapy (WBRT) for leptomeningeal metastasis (LM) from lung adenocarcinoma have not been established. Particularly, the impact of EGFR mutations and ALK rearrangements on survival remains unclear. This retrospective study evaluated the prognosis and prognostic factors of patients receiving WBRT for LM. We evaluated overall survival (OS) from WBRT initiation and clinical variables in 80 consecutive patients receiving WBRT for LM from lung adenocarcinoma at our institution between June 2013 and June 2021. After a median follow-up of 5.2 (range 0.5-56.5) months, the median OS was 6.2 months (95% CI 4.4-12.4). Of the 80 patients, 51 were classified as EGFR/ALK mutant (EGFR: 44; ALK: 6; both: 1) and 29 as wild-type. The median OS was 10.4 (95% CI 5.9-20.9) versus 3.8 (95% CI 2.5-7.7) months in the EGFR/ALK-mutant versus wild-type patients (HR = 0.49, P = 0.0063). Multivariate analysis indicated that EGFR/ALK alterations (HR = 0.54, P = 0.021) and Eastern Cooperative Oncology Group performance status (ECOG PS) of 0-1 (HR = 0.25, P < 0.001) were independent factors associated with favorable OS. Among the patients who underwent brain MRI before and after WBRT, intracranial progression-free survival was longer in the 26 EGFR/ALK-mutant than 13 wild-type patients (HR = 0.31, P = 0.0039). Although the prognosis of patients receiving WBRT for LM remains poor, EGFR/ALK alterations and good ECOG PS may positively impact OS in those eligible for WBRT.

Efficacy of different platforms in detecting EGFR mutations using cerebrospinal fluid cell-free DNA from non-small-cell lung cancer patients with leptomeningeal metastases.

BACKGROUND: Cell-free tumor DNA (ctDNA) obtained through liquid biopsy is useful for the molecular analysis of advanced non-small-cell lung cancer (NSCLC). Few studies have directly compared analysis platforms in terms of their diagnostic performance in analyzing ctDNA obtained from the cerebrospinal fluid (CSF) of patients with leptomeningeal metastasis (LM). METHODS: We prospectively analyzed patients with epidermal growth factor receptor (EGFR)-mutant NSCLC who were subjected to CSF analysis for suspected LM. To detect EGFR mutations, CSF ctDNA was analyzed using the cobas EGFR Mutation Test and droplet digital polymerase chain reaction (ddPCR). CSF samples from osimertinib-refractory patients with LM were also subjected to next-generation sequencing (NGS). RESULTS: Significantly higher rates of valid results (95.1% vs. 78%, respectively, p = 0.04) and EGFR common mutation detection (94.3% vs. 77.1%, respectively, p = 0.047) were obtained through ddPCR than through the cobas EGFR Mutation Test. The sensitivities of ddPCR and cobas were 94.3% and 75.6%, respectively. The concordance rate for EGFR mutation detection through ddPCR and the cobas EGFR Mutation Test was 75.6% and that for EGFR mutation detection in CSF and plasma ctDNA was 28.1%. In osimertinib-resistant CSF samples, all original EGFR mutations were detected through NGS. MET amplification and CCDC6-RET fusion were demonstrated in one patient each (9.1%). CONCLUSIONS: The cobas EGFR Mutation Test, ddPCR, and NGS appear to be feasible methods for analyzing CSF ctDNA in patients with NSCLC and LM. In addition, NGS may provide comprehensive information regarding the mechanisms underlying osimertinib resistance.

Molecular characteristics and prognostic factors of leptomeningeal metastasis in non-small cell lung cancer.

BACKGROUND: Non-small cell lung cancer with leptomeningeal metastasis (NSCLC-LM) is emerging as a new management challenge for oncologists and is associated with poor prognosis. This study aimed to investigate the molecular characteristics and prognostic factors of NSCLC-LM. METHODS: This retrospective study included 97 patients with NSCLC-LM between January 2015 and October 2021. Progression-free survival (PFS) and overall survival (OS) were evaluated. Gene mutations were detected by next-generation sequencing (NGS). RESULTS: The median PFS and OS were 8.4 (95 % confidence interval [CI]: 4.839-11.901) and 14.0 (95 % CI: 9.254-18.746) months, respectively. Sixty-seven patients harboured epidermal growth factor receptor-mutated (EGFRm): L858R (34), 19del (29), T790M (13), and G719C with L861Q (1). Other mutations included ALK (5), ROS1 (3), KRAS (1), TP53 (14), MET amplification (6). The detection rate and types of circulating tumour DNA (ctDNA) in the cerebrospinal fluid (CSF) samples were higher than the paired plasma samples. Patients with EGFR mutations had a longer median OS than those without mutations (19.0 vs. 13.0 months, P = 0.015). Patients with gene mutations had shorter median OS than those without mutations, such as ALK (11.8 vs. 19.9 months, P = 0.014), ROS1 (12.7 vs. 19.8 months, P = 0.014), KRAS (4.0 vs. 19.0 months, P = 0.005), TP53 (15.0 vs. 19.0 months, P = 0.014), and MET amplification (6.0 vs. 19.0 months, P = 0.003). Multivariate analysis indicated that MET amplification was an independent predictor of poor survival. Along with Eastern Cooperative Oncology Group Performance Status (ECOG PS) ≥ 3, LM accompanied with brain parenchymal metastasis (BPM), extracranial disease, and seizures were independent predictors of poor survival, whereas intrathecal chemotherapy, and third-generation EGFR-TKIs were independent predictors of favorable survival. CONCLUSIONS: CSF ctDNA detected using NGS had a high sensitivity for NSCLC-LM, showing high potential in detecting driver and drug-resistant gene mutations. Genomic profiles, combined with clinically relevant prognostic factors, will guide individualised treatments and improve the outcomes of NSCLC-LM patients.

Osimertinib Combined with Systemic Chemotherapy for EGFR Mutant, T790M-Negative, Non-Small Cell Lung Cancer Patients Who Develop Leptomeningeal Metastases with Extracranial Progression to Prior EGFR TKI.

Leptomeningeal metastasis (LM) is a rare but fatal clinical condition with a short survival time. The incidence of LM from epidermal growth factor receptor mutant (EGFRm) non-small cell lung cancer (NSCLC) has increased due to the limited efficacy of first- or second-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in the central nervous system (CNS). Osimertinib is a third-generation, irreversible, CNS penetrant, oral EGFR TKI that demonstrates promising efficacy in CNS metastases regardless of T790M. Herein, we report four cases of T790M-negative EGFRm NSCLC patients treated with osimertinib combined with systemic chemotherapy, who progressed on prior EGFR TKI and developed LM with extracranial lesions. The combination treatment was well tolerated, and the mean overall survival from LM diagnosis was 14.7 months (95% confidence interval, 10.4 to 19.0). These results suggest that osimertinib combined with systemic chemotherapy would be a reasonable treatment option for T790M-negative EGFRm NSCLC patients who develop LM with extracranial progression to prior EGFR TKI. A further prospective study is warranted.

Prognosticators of osimertinib treatment outcomes in patients with EGFR-mutant non-small cell lung cancer and leptomeningeal metastasis.

PURPOSE: Leptomeningeal metastasis (LM) is a serious complication of non-small cell lung cancer (NSCLC), particularly in patients with EGFR mutations. In this study, we investigated the survival outcomes of patients with EGFR-mutant NSCLC who have developed LM and explored the factors associated with their survival. METHODS: From April 2018 to November 2021, patients with EGFR-mutant NSCLC who underwent cerebrospinal fluid (CSF) sampling under the clinical suspicion of LM were enrolled. The patients' clinicodemographic characteristics, treatment history including whole-brain radiation therapy (WBRT), overall survival (OS), and intracranial progression-free survival (icPFS) were measured. EGFR mutations in cell-free tumor DNA (ctDNA) of CSF, including T790M mutation, were analyzed. RESULTS: We enrolled 62 patients with NSCLC. The median time form diagnosis to LM was 23.1 months and 16 (25.8%) patients had history of prior third-generation EGFR-TKI use. EGFR mutation in CSF ctDNA was detected in 53 patients (85.5%); of them, 10 (16.1%) had T790M mutation. The patients' icPFS and OS after osimertinib were 6.43 and 9.37 months, respectively, and were comparable among patients with different sensitive EGFR mutations, indicating that EGFR mutation status did not affect osimertinib efficacy. Patients who received WBRT after LM had numerically higher icPFS and OS compared to those without. Multivariate analysis revealed that lack of prior exposure to third-generation EGFR-TKI was associated with better OS. CONCLUSIONS: Osimertinib is effective in patients with EGFR-mutant NSCLC who developed LM and prior third-generation EGFR-TKI use was associated with poor survival in these patients. The role of WBRT warrants further investigation.

Clinical Outcomes of Patients with Epidermal Growth Factor Receptor-Mutated Non-Small-Cell Lung Cancer with Leptomeningeal Metastasis in the Modern Target Therapy Era.

BACKGROUND: Leptomeningeal metastasis (LM) is a severe complication in patients with non-small-cell lung cancer (NSCLC) and the optimal treatment strategy remains a challenge. This study aimed to investigate the treatment strategies and clinical outcomes in these patients. METHODS: We retrospectively reviewed the data of 44 patients with epidermal growth factor receptor (EGFR)-mutated NSCLC with LM between 2014 and 2020 at our institute. The patient characteristics, treatment approaches, LM progression-free survival (LMPFS) and overall survival (OS) after the diagnosis of LM (OSLM) were analyzed. RESULTS: The median OSLM was 16.0 months and the 3-year OS rate was 22.5%. The PFSLM in EGFR T790M-positive NSCLC patients with leptomeingeal disease was significantly improved by initiation of third-generation tyrosine kinase inhibitors (TKIs) compared with that of patients who were T790M negative (14.0 vs. 7.0 months; P = 0.030). A significantly higher LM disease control rate was shown in patients who received third-generation TKIs compared with previous generations of TKIs (90.1% vs. 60.0%; P = 0.024). Better Eastern Cooperative Oncology Group performance status, EGFR exon 19del, and clinical improvement of LM after therapy were independently associated with better OS. CONCLUSIONS: The survival of patients with NSCLC with LM has improved in the target therapy era. Our study provided real-world clinical evidence that patients with EGFR-mutated NSCLC who developed LM from previous TKIs can be benefit from third-generation EGFR-TKIs, especially for patients with EGFR T790M-positive.

Brain parenchymal and leptomeningeal metastasis in non-small cell lung cancer.

Patients with advanced non-small cell lung cancer (NSCLC) are prone to brain metastases (BM), which essentially include brain parenchymal metastases (PM) and leptomeningeal metastases (LM). We conducted a retrospective study to comprehensively assess the clinical characteristics and risk factors of patients with advanced NSCLC who develop PM and LM. Patients with advanced NSCLC were enrolled. These patients were then divided into three groups for analysis: patients without BM (No-BM), patients with PM and patients with LM. Data on clinical characteristics of each patient at the time of diagnosis advanced NSCLC were extracted and analyzed. In addition, prediction models were developed and evaluated for PM and LM. A total of 592 patients were enrolled in the study. BM was present in 287 patients (48.5%). Among them, 185 and 102 patients had PM or LM. Patients with LM had a higher proportion of EGFR exon 21point mutations (L858R) compared to patients with No-BM and PM (p < 0.0001). The median time to the onset of PM and LM from the diagnosis of advanced NSCLC was 0 months and 8.3 months, respectively. Patients with LM had a statistically shorter over survival (OS) compared to either No-BM or PM patients (p < 0.0001). Based on independent predictive variables, two nomogram models were constructed to predict the development of PM and LM in advanced NSCLC patients, and the C-indexes were 0.656 and 0.767, respectively. Although both considered as BM, PM and LM had different clinical characteristics. And the nomogram showed good performance in predicting LM development, but not PM.

Genotyping of cerebrospinal fluid in lung cancer patients with leptomeningeal metastasis.

BACKGROUND: The prognosis of non-small-cell lung cancer (NSCLC) with leptomeningeal metastasis (LM) is poor. Detection of cell-free DNA (cfDNA) by next generation sequencing (NGS) in cerebrospinal fluid (CSF) may facilitate diagnosis of LM and identification of drug resistance mechanisms, yet its clinical use needs to be further verified. METHODS: We performed a retrospective cohort study to assess the genetic profiles of paired CSF and plasma samples in lung cancer patients with LM. Of 17 patients screened, a total of 14 patients with LM and paired NGS tests were enrolled. RESULTS: All patients harbor driver gene mutations, including 12 epidermal growth factor receptor (EGFR) activating mutations, 1 anaplastic lymphoma kinase (ALK) rearrangement, and 1 ROS-1 fusion. Genetic mutations were detected in CSF cfDNA from 92.9% patients (13/14), which was significantly higher than that from the plasma (9/14, 64.2%). The mutations were highly divergent between CSF and plasma cfDNA, with a concordance rate of 24.38% and 10 mutations shared by the two media. CSF cfDNA could also benefit the analysis of resistance mechanisms to targeted therapies. In five patients who experienced progression on 1st or 2nd generation EGFR-tyrosine kinase inhibitors (TKIs), RB1 mutation, and amplification of MET and EGFR were detected in CSF cfDNA only. In eight patients with LM progression on osimertinib resistance, EGFR amplification was detected in CSF cfDNA from four patients, whereas no CNVs were detected in the matched plasma samples. CONCLUSIONS: In conclusion, CSF could be superior to plasma in providing a more comprehensive genetic landscape of LM to find out drug resistance mechanisms and guide subsequent treatments.

Systemic Treatment Patterns and Outcomes in Patients With EGFR Mutated Non-small Cell Lung Cancer and Leptomeningeal Disease.

INTRODUCTION: Leptomeningeal (LM) disease occurs in 9% to 10% of EGFR mutated non-small cell lung cancer (NSCLC) cases. The natural history and optimal systemic treatment strategies for this disease are not well-characterized, particularly in the era of osimertinib. MATERIALS AND METHODS: We identified 54 patients with EGFR mutated NSCLC and LM disease diagnosed between January 3, 2000 to March 31, 2020 and treated at an academic oncology practice in Seattle, Washington. We abstracted demographic, tumor, treatment, and outcome data from the electronic medical record. Univariate Cox models were run to evaluate the association between post-LM disease systemic therapy and overall survival. Differences in LM disease natural history and healthcare utilization between groups were assessed using Student's t test or a chi-squared test. RESULTS: Patients that received osimertinib prior to LM disease had a longer median time to LM disease diagnosis and trended toward better performance status than those that did not. Patients that received any post-LM disease systemic therapy had a lower risk of death relative to those that did not (HR 0.17, P < .001), with a suggestion that osimertinib-containing regimens result in longer median overall survival. Emergency department, hospital and hospice utilization were not associated with receipt of post-LM disease systemic therapy. CONCLUSION: Prior exposure to osimertinib appears to favorably influence the natural history of LM disease. Any systemic therapy after LM disease diagnosis is associated with longer survival and does not increase healthcare utilization. Additional research is needed to assess whether an osimertinib-containing regimen confers a survival benefit after LM disease diagnosis among patients who received prior osimertinib.

Assessing CSF ctDNA to Improve Diagnostic Accuracy and Therapeutic Monitoring in Breast Cancer Leptomeningeal Metastasis.

PURPOSE: Cerebrospinal fluid (CSF) cytology is the gold standard diagnostic test for breast cancer leptomeningeal metastasis (BCLM), but has impaired sensitivity, often necessitating repeated lumbar puncture to confirm or refute diagnosis. Further, there is no quantitative response tool to assess response or progression during BCLM treatment. EXPERIMENTAL DESIGN: Facing the challenge of working with small-volume samples and the lack of common recurrent mutations in breast cancers, cell-free DNA was extracted from the CSF and plasma of patients undergoing investigation for BCLM (n = 30). ctDNA fraction was assessed by ultra-low-pass whole genome sequencing (ulpWGS), which does not require prior tumor sequencing. RESULTS: In this proof-of-concept study, ctDNA was detected (fraction ≥0.10) in the CSF of all 24 patients with BCLM+ (median ctDNA fraction, 0.57), regardless of negative cytology or borderline MRI imaging, whereas CSF ctDNA was not detected in the six patients with BCLM- (median ctDNA fraction 0.03, P < 0.0001). Plasma ctDNA was only detected in patients with extracranial disease progression or who had previously received whole brain radiotherapy. ctDNA fraction was highly concordant with mutant allele fraction measured by tumor mutation-specific ddPCR assays (r = 0.852; P < 0.0001). During intrathecal treatment, serial monitoring (n = 12 patients) showed that suppression of CSF ctDNA fraction was associated with longer BCLM survival (P = 0.034), and rising ctDNA fraction was detectable up to 12 weeks before clinical progression. CONCLUSIONS: Measuring ctDNA fraction by ulpWGS is a quantitative marker demonstrating potential for timely and accurate BCLM diagnosis and therapy response monitoring, with the ultimate aim to improve management of this poor-prognosis patient group.

Combination treatment with bevacizumab plus erlotinib for meningeal carcinomatosis of afatinib-resistant EGFR mutated lung cancer without T790M mutation: a case report.

Meningeal carcinomatosis in lung cancer is known to have a very poor prognosis. Here we report a case in which bevacizumab plus erlotinib (BE) was effective against meningeal carcinomatosis from afatinib-resistant EGFR mutation-positive lung cancer. A 61-year-old man started afatinib, a 2nd generation molecular targeting drug, as first-line treatment for lung adenocarcinoma cT1bN0M1a stage IVA harboring EGFR exon19 deletion mutation. This treatment shrank the tumor and allowed sustained control of tumor growth. After 19 months from the start of treatment, head MRI revealed brain metastasis in the cerebellum and meningeal carcinomatosis with loss of appetite and slurred speech, in response to which whole-brain irradiation was performed. Head MRI 1 month after whole-brain irradiation showed no change in the disseminated lesions of the cerebellum. In Japan, osimertinib treatment after failure of EGFR-TKI treatments requires the T790M mutation in the tumor, blood or body fluid, so BE treatment was started as second-line treatment. Brain MRI showed improvement in cerebellar disseminated lesions 1 month after the start of BE treatment. BE treatment controlled intrapulmonary metastases, pleural disseminated lesions and meningeal carcinomatosis for 6 months. BE treatment as second-line treatment should be considered as an option for meningeal carcinomatosis of EGFR tyrosine kinase inhibitor (TKI) -resistant EGFR mutated lung cancer.

Successful treatment using targeted therapy, radiotherapy, and intrathecal chemotherapy in a patient with leptomeningeal metastasis with an epidermal growth factor receptor exon 20 insertion mutation: a case report.

Leptomeningeal metastasis (LM) is a disastrous complication in lung cancer. LM patients with oncogene-addicted non-small cell lung cancer (NSCLC) have a relatively better prognosis than those with the wild-type counterpart; however, overall post-LM survival is short. Additionally, the high heterogenicity of the LM entity creates a treatment challenge, and to date, no standard strategy has been established. This article describes a female lung adenocarcinoma patient with a resistant epidermal growth factor receptor (EGFR) exon20ins mutation who developed LM only 11 months after radical surgery IIIA (pT1bN2). Intrathecal chemotherapy (ITC), whole-brain radiotherapy (WBRT) with a simultaneous integrated boost (SIB) followed by Osimertinib was initiated. The cerebrospinal fluid (CSF) cytology turned negative. The first remission lasted 6 months, then bone metastases occurred, and the LM progressed. An Ommaya reservoir was implanted. ITC with pemetrexed and anlotinib was administered. A CSF next-generation sequencing (NGS) examination revealed EGFR exon20ins (p. A767_V769 dup 1.5%), which was different from that of the primary tumor (p. V769_D770 ins ASV 17.48%). The CSF cytology then turned negative again; however, the patient succumbed to the disease in December 2020. The patient's post-LM overall survival (OS) time was 13.5 months. This case is novel and of great value. Clinicians should pay special attention to populations at high risk of developing LM. Early detection followed by active intervention, including ITC, RT, and systemic treatment, will result in a better prognosis. The NGS of CSF is fundamental to understanding the genetic profiles of LM and providing effective and precise treatment.

Erlotinib combined with bevacizumab and chemotherapy in first line osimertinib-resistant NSCLC patient with leptomeningeal metastasis: A case report.

RATIONALE: Leptomeningeal metastasis (LM) is a fatal complication of advanced non-small cell lung cancer (NSCLC) with a poor prognosis. Osimertinib is a promising option for NSCLC with LM harboring epidermal growth factor receptor (EGFR) mutation. However, therapeutic approaches remain a challenge for osimertinib resistant NSCLCs with LM. Although studies have reported that the first/second-generation EGFR-tyrosine kinase inhibitors were active against osimertinib-resistant NSCLC with EGFR C797S and sensitive mutation (SM), the resistance inevitably occurred due to the development of the EGFR SM/C797S/T790M triple mutations. PATIENT CONCERNS: A 48-year-old woman was diagnosed with stage IV lung adenocarcinoma harboring the EGFR mutation in the combination of chest computed tomography, biopsy and amplification refractory mutation system-polymerase chain. One year and a half after oral administration of osimertinib, the patient progressed to extensive LM. DIAGNOSES: Magnetic resonance images of the brain showed extensive LM. Exfoliated tumor cells from cerebrospinal fluid (CSF) were positive detected by lumbar puncture and the cytology examination. EGFR mutations (exon19 E746_T751delinsI and exon20 C797S) in CSF circulating tumor DNA were detected by next-generation sequencing (NGS). INTERVENTIONS: Pemetrexed (800 mg day 1), cis-platinum (40 mg day 1-3) combined with bevacizumab (400 mg day 1) every 3 weeks were administered to the patient. After 1 cycle, due to optic nerve invasion, erlotinib was applied 150 mg/d combined with previous regimen. The patient continued erlotinib monotherapy after 6 cycles. OUTCOMES: After LM, erlotinib combined with pemetrexed, cis-platinum and bevacizumab were administered to the patient for 4.25 months based on the CSF NGS. Then, the patient continued erlotinib monotherapy and appeared disease progression after 10 months. The overall survival is 35 months. LESSONS: LM is a fatal complication of advanced NSCLC with a poor prognosis. NGS profiling of CSF circulating tumor DNA is important in NSCLC patients with LM and erotinib plus bevacizumab and chemotherapy is a promising option for patients with LM harboring EGFR C797S/SM.

Trametinib overcomes KRAS-G12V-induced osimertinib resistance in a leptomeningeal carcinomatosis model of EGFR-mutant lung cancer.

Leptomeningeal carcinomatosis (LMC) occurs frequently in non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations and is associated with acquired resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs). However, the mechanism by which LMC acquires resistance to osimertinib, a third-generation EGFR-TKI, is unclear. In this study, we elucidated the resistance mechanism and searched for a novel therapeutic strategy. We induced osimertinib resistance in a mouse model of LMC using an EGFR-mutant NSCLC cell line (PC9) via continuous oral osimertinib treatment and administration of established resistant cells and examined the resistance mechanism using next-generation sequencing. We detected the Kirsten rat sarcoma (KRAS)-G12V mutation in resistant cells, which retained the EGFR exon 19 deletion. Experiments involving KRAS knockdown in resistant cells and KRAS-G12V overexpression in parental cells revealed the involvement of KRAS-G12V in osimertinib resistance. Cotreatment with trametinib (a MEK inhibitor) and osimertinib resensitized the cells to osimertinib. Furthermore, in the mouse model of LMC with resistant cells, combined osimertinib and trametinib treatment successfully controlled LMC progression. These findings suggest a potential novel therapy against KRAS-G12V-harboring osimertinib-resistant LMC in EGFR-mutant NSCLC.

Molecular Determinants of Medulloblastoma Metastasis and Leptomeningeal Dissemination.

Medulloblastoma is the most common malignant brain cancer in pediatrics consisting of four molecular subgroups, namely wingless (WNT), sonic hedgehog (SHH), Group 3, and Group 4. One of the biggest challenges in the clinical management of this disease is the leptomeningeal dissemination (LMD) of tumor cells with high morbidity and mortality. Many molecular regulators to date have been identified to participate in medulloblastoma metastasis. In the SHH subgroup, the co-upregulation of CXCR4 and PDGFR, as well as the activation of c-MET, show significant promigratory effects on medulloblastoma cells. Amplification or overexpression of genes on the long arm of chromosome 17, such as LASP1 and WIP1, facilitates tumor invasion in both Group 3 and Group 4 medulloblastomas. PRUNE1, NOTCH1, and MYC interactor JPO2 are more specific genetic drivers of metastatic Group 3 tumors. The RAS/MAPK and PI3K/AKT pathways are two crucial signal transduction pathways that may work as the convergent downstream mechanism of various metastatic drivers. Extracellular signals and cellular components in the tumor microenvironment also play a vital role in promoting the spread and colonization of medulloblastoma cells. For instance, the stromal granule cells and astrocytes support tumor growth and dissemination by secreting PlGF and CCL2, respectively. Importantly, the genetic divergence has been determined between the matched primary and metastatic medulloblastoma samples. However, the difficulty of obtaining metastatic medulloblastoma tissue hinders more profound studies of LMD. Therefore, identifying and analyzing the subclone with the metastatic propensity in the primary tumor is essential for future investigation.

Detection and significance of exosomal mRNA expression profiles in the cerebrospinal fluid of patients with meningeal carcinomatosis.

Exosomes are cell-derived membrane vesicles with cargo that can be transported into receiver cells to exert their biological roles. Exosomal RNA signature profiles and exosome-derived proteomics are often used to explore the molecular regulation of diseases, and can mirror the conditional state of their tissue of origin, thus serving as biomarkers. The onset of meningeal carcinomatosis (MC) is concealed, and early diagnosis is difficult. To enable early diagnosis of MC, it is essential to identify new biomarkers. Few studies have investigated the function of exosomes in MC. In this study, high-throughput sequencing was used to examine the mRNA profiles of exosomes in the cerebrospinal fluid (CSF) of patients with MC. We further analyzed the functions and signaling pathways associated with the differentially expressed genes in exosomes to reveal the putative mechanisms by which the exosomal mRNAs function in MC. In summary, this study identified biomarker candidates for MC, and provided new insights into the significant role of exosomal mRNA regulation in MC.

A nanowire-based liquid biopsy method using cerebrospinal fluid cell-free DNA for targeted management of leptomeningeal carcinomatosis.

PURPOSE: This study aimed to evaluate whether genotyping cell free DNA (cfDNA) in the cerebrospinal fluid (CSF) may be helpful in managing leptomeningeal carcinomatosis (LMC) of EGFR-mutant non-small cell lung cancer (NSCLC). METHODS: Patients with EGFR-mutant NSCLC who progressed as LMC after 3rd-generation tyrosine kinase inhibitors (EGFR-TKIs) were evaluated. A nanowire-based cfDNA assay was performed for genotyping cfDNA from the CSF and plasma. We focused on de novo EGFR C797S mutation and MET amplification, which are the most common mechanisms of resistance to 3rd-generation EGFR-TKIs. RESULTS: Among 11 patients, five (45.5%) had progression only at the leptomeninges. The tumor-associated CSF-cfDNA was identified in eight (72.7%) patients, and plasma-cfDNA in six (54.5%) patients. In the CSF-cfDNA, EGFR C797S mutation and MET amplification were detected in four (36.3%) and two (18.2%) patients, respectively. Of four patients with the C797S-positive LMC, only one had concurrent CSF-T790M mutation. Three patients who had the C797S-positive LMC without CSF-T790M mutation, received 1st-2nd generation EGFR-TKIs and showed clinical benefits for 20.8, 17.8, and 8.8 weeks, respectively. Serial assessment with cfDNA in these patients demonstrated that the CSF levels of C797S mutation were decreased with radiological or neurological improvement but the plasma levels of T790M mutation were markedly increased before objective progression. CONCLUSION: Genotyping CSF-cfDNA by the nanowire-based assay is feasible and effective in guiding the treatment of LMC in patients with EGFR-mutant NSCLC.