RecruitingPhase 1Drug trialIntrathecal Injection Pemetrexed And Bevacizumab in Patients With Leptomeningeal Metastases in NSCLCThis is a prospective, single-arm, phase Ia clinical study, which was designed to evaluate the efficacy and safety of Pemetrexed Combined With Bevacizumab Intrathecal Injection in Patients With Leptomeningeal Metastases in NSCLC.