The goal of this clinical trial is to learn whether amivantamab combined with intrathecal pemetrexed is safe and may help treat leptomeningeal metastasis in adults with EGFR-mutant lung adenocarcinoma. Leptomeningeal metastasis occurs when cancer cells spread to the membranes surrounding the brain and spinal cord or to the cerebrospinal fluid. It is a serious complication of advanced lung cancer and is difficult to treat because many systemic drugs do not reach high enough levels in the cerebrospinal fluid.
The main questions this study aims to answer are:
What medical problems do participants have when receiving amivantamab combined with intrathecal pemetrexed? How long do participants live without their disease getting worse after receiving this treatment? How long do participants survive after starting this treatment?
Participants will:
Receive amivantamab by intravenous infusion according to the study schedule. Receive intrathecal pemetrexed, together with dexamethasone and normal saline, once every week.
Continue their original EGFR tyrosine kinase inhibitor treatment as determined by the study doctor.
Have cerebrospinal fluid pressure measured and cerebrospinal fluid samples collected before each intrathecal treatment.
Have tests of cerebrospinal fluid, including routine tests, biochemical tests, tumor markers, albumin, IgG, and cytology.
Have imaging tests, including enhanced MRI, about every 3 months to check the disease.
Be followed by clinic visits and/or telephone calls to collect information about survival, disease status, side effects, and any later cancer treatments.