The goal of this clinical trial is to learn if the Thiotepa administration via Ommaya Reservoir works to treat non-small cell lung cancer with leptomeningeal metastases resistant to EGFR TKI. The main questions to answer are:
Is Thiotepa administration via Ommaya Reservoir safe to inject? How effective is thiotepa via Ommaya Reservoir in intracranial-disease control? Participants will：
Stage 1: Intrathecal injection of 10 mg thiotepa via Ommaya reservoir, twice every week, for 4 consecutive weeks; Stage 2: Intrathecal injection of 10 mg thiotepa via Ommaya reservoir, once every week, for 4 consecutive weeks; Stage 3: Intrathecal injection of 10 mg thiotepa via Ommaya reservoir, once a month, for 4 consecutive months; Before each intrathecal administration, a preliminary intrathecal injection of dexamethasone, 2.5 mg/dose, is given.
Age between 18 and 75 years.
Male or female of non-childbearing potential, or female of childbearing potential who is not pregnant or lactating.
ECOG performance status of 0 to 2, with no deterioration within the past 7 days.
Radiological and/or cerebrospinal fluid (CSF) cytological evidence of leptomeningeal metastases (LM). The diagnosis of non-small cell lung cancer (NSCLC) must be confirmed by histological and/or cytological examination.
Patients requiring ventriculoperitoneal (VP) shunt placement due to elevated intracranial pressure.
History of epilepsy unrelated to leptomeningeal metastases.
Evidence of any neurological functional failure, including severe encephalopathy, grade 3 or 4 leukoencephalopathy as shown on imaging, or a Glasgow Coma Scale (GCS) score < 11.
Evidence of any extensive and fatal progressive systemic disease with no effective treatment available.