Immune Checkpoint Inhibitor Combined With Pemetrexed Intrathecal Injection for Leptomeningeal Metastasis From Solid Tumors

This is an open-label, single-arm, phase I/II trial of immune checkpoint inhibitor combined with pemetrexed intrathecal injection for leptomeningeal metastasis from solid tumors.

Inclusion Criteria: 1. Histologically or cytologically confirmed diagnosis of solid tumors; Cerebrospinal fluid cytopathology is positive. 2. Male or female aged between 18 and 75 years; Normal liver and kidney function; WBC≥4000/mm3, Plt≥100000/mm3. 3. No history of severe nervous system disease; No severe dyscrasia. Exclusion Criteria: 1. Any evidence of nervous system failure, including severe encephalopathy, grade 3 or 4 leukoencephalopathy on imaging, and Glasgow Coma Score less than 11. 2. Any evidence of extensive and lethal progressive systemic diseases without effective treatment. 3. A history of HIV or AIDS, active hepatitis B or C infection, previous anti-PD1 therapy-induced pneumonitis, or have ongoing \>Grade 2 adverse events of such therapy; or ongoing autoimmune disease that required systemic treatment in the past 2 years. 4. Patients with poor compliance or other reasons that were unsuitable for this study.