Inclusion Criteria:  age 18 years or older, gender not limited; A definite diagnosis of Leptomeningeal metastases from lung cancer, including cerebrospinal fluid cytology and/or neuroimaging; Have a clear history of lung cancer, including histopathological diagnosis, or cytopathology combined with imaging diagnosis Patients who received any of EGFR inhibitors (gefitinib, erlotinib, afatinib, osimertinib etc.) meet the diagnostic criteria for secondary resistance and were in a slow progression stage Detection results of cerebrospinal fluid, blood gene or lung tissue specimens showed EGFR mutation, and immunohistochemistry results of cerebrospinal fluid, blood gene or lung tissue showed positive EGFR expression Bone marrow, liver, kidneys and blood clotting function are relatively stable  Exclusion Criteria:  Eastern Cooperative Oncology Group scored > 2 points Patients had poor compliance, or for other reasons the investigator considered them unsuitable to participate in the study