High-dose Furmonertinib Combined With Bevacizumab and Intrathecal Pemetrexed Chemotherapy in Patients With EGFR-mutated Non-small Cell Lung Cancer and Meningeal Metastasis

Inclusion Criteria: * Histological or cytological localization is NSCLC; * confirmed EGFR exon 19 deletion mutation(19del) or EGFR exon 21L858R mutation (L858R) or EGFR exon 20 T790M mutation (T790M)）; * Clinical diagnosis of meningeal aggravation: clinical symptoms of intracranial hypertension (headache, dizziness, vomiting, etc.) + imaging confirmation (cerebral MRI diagnosis of meningeal aggravation) or cerebrospinal fluid cytology confirmation; * for patients with symptoms who are considered to need temporary brain local. Treatment of cough receiving adrenal corticosteroids must be kept stable or reponse for at least 1 week before the first trial of the drug preparation; * Newly diagnosed meningeal metastasis, including meningeal metastasis after previous brain surgery and/or local radiotherapy for solid metastatic disease; * Patients had not received previous systemic treatment for advanced NSCLC or had meningeal metastases after treatment with one third-generation EGFR-TKI. * Obtain informed consent signed by the patient's legal representative; * Aged ≥18 years and ≤75 years; * Eastern Tourism Cooperation Group (ECOG) Physical condition evaluation 0-1; * Life expectancy ≥12 week; * Able to follow the requirements of the study protocol and confirmation procedures, and able to accept cranial wall medications; * contraception. Exclusion Criteria: * Mixed non-small cell and small cell carcinoma, or squamous cell carcinoma as the main pathological type; * Known EGFR exon 20 C797X mutation (C797X); * history of hypersensitivity reaction to active or inactive excipients of furmonertinib, bevacizumab or pemetrexed or to drugs of similar structure or class to the investigational drug; * Brain metastases have previously received whole-brain radiotherapy; * Currently participating in an interventional clinical trial, or having received other study drugs or study devices within 4 weeks before the first study drug; * Patients who have received solid organ or blood system transplantation; * Patients with severe intracranial hypertension symptoms that cannot be relieved by discontinuation of dexamethasone and/or glycol treatment, or patients in intensive care; * Ensure control of the patient's symptomatic pericardial, peritoneal, and pleural effusions; * History of cancer in the last five years Other malignancies or a history of other malignancies; * Recent active digestive events, such as duodenitis, ileitis, intestinal perforation, intestinal catheters, or other conditions that may cause gastrointestinal tract or perforation; or refractory vomiting, chronic gastrointestinal disease, inability to swallow study drugs, or previous colorectal cancer resection that prevents adequate drug absorption; * The patient has a physique that is prone to Japanese language learning or has active Japanese language learning;Central squamous cell carcinoma orPatients at greater risk for hemoptysis; Any diamond event ≥ CTCAE grade 3, presence of open wounds, injuries or fractures in the 28th century before the first creation; if in the first Asthma was accepted 28 days before the organization meeting, the wound treatment should be evaluated by the interval period; * History of arterial thromboembolism within the last 6 months, including vascular cerebral accident, myocardial infarction, transient cerebral contemplation; * History of grade 4 venous thrombosis within the last 6 months, including fire embolism; * The presence of any severe or uncontrolled systemic evidence, including difficult-to-control hypertension (systolic blood pressure ≥150 mmHg and/or diastolic blood pressure ≥100 mmHg), uncontrolled diabetes, etc.; * Active infections include, for example, hepatitis B, hepatitis C, and human immunodeficiency virus (HIV) infections (including those requiring intravenous therapy, active hepatitis B infection includes patients with positive hepatitis B surface test based on serological assessment and hepatitis B virus DNA \>1000 copies/ml); * previous history of interstitial lung disease, drug-induced interstitial lung disease, pneumonitis requiring steroid therapy, or any evidence of active interstitial lung disease; * The first 28-day inspection of the drug preparation showed Lack of adequate bone marrow reserve or organ function（Within 2 weeks before blood test,No blood transfusion or blood products, granulocyte colony-stimulating factor or other hematopoietic stimulating factors were used for repair）: * Absolute neutrophil count \<1.5 × 109/L; continuous count \<100×109/L; hemoglobin \<90 g/L; * Alanine aminotransferase \> 2.5 times Upper limit of normal value (Upper limit of normal）; Aspartate aminotransferase\>2.5 times ULN; Total bilirubin\>1.5 times ULN;or liver transplant patients with AST and/or ALT \> 5× ULN; * Albumin \<30 g/L; * Serum creatinine \>1.5 times ULN, and Creatinine clearance \<50 mL/min（Measured or calculated by Cockcroft and Gault formula); * International normalized ratio (INR) \> 1.5,Partially activated zymogen time（APTT\>1.5 times Upper limit of normal; * Urine protein ≥++, and 24-hour protein \>2.0g; * Any of the following Bishop criteria: * Clinically significant resting electrocardiogram rhythm, respiratory, or morphological abnormalities, such as left bundle branch block, third-degree myocardial insufficiency, and second-degree myocardial insufficiency, within 28 days before the first study drug perfume; * Possibility Interphase Factors that increase the risk of prolonged or arrhythmic events, such as heart failure, congenital long Quantum Dots Syndrome, long Quantum Dots Family history or first-degree relatives 40 Sudden death due to coma or known prolonged Quantum Dots Any sudden or difficult to fully compensate low potassium tariffs, low tariff tariffs, and low tariff-to-tariff tariffs during the period; * Left ventricular ejection fraction (LVEF)Left ventricular ejection fraction）\<50%, recent History of myocardial infarction, severe or unstable angina, or coronary artery bypass grafting within the past month or heart failure≥New York Heart Association (New York Heart Association (NYHA) 2 class; * Pregnancy or breastfeeding.