Intrathecal Pemetrexed for Recurrent Leptomeningeal Metastases From Non-small Cell Lung Cancer

It has been proved that intrathecal chemotherapy is the main treatment strategy for leptomeningeal metastases. At present, the commonly used drugs for intrathecal chemotherapy include methotrexate, cytarabine, and liposomal cytarabine. In recent decades, no new effective drugs have been discovered for intrathecal chemotherapy. The recurrence of leptomeningeal metastases is inevitable even after aggressive treatment. There is no effective treatment for recurrent leptomeningeal metastases after comprehensive treatment which includes intrathecal methotrexate and/or cytarabine, central nervous system radiation therapy, systemic chemotherapy as well as tyrosine-kinase inhibitor drugs. The quality of life is extremely poor, and the patients always die in short time. Pemetrexed is a newer multitargeted antifolate which has shown activity in various tumors. It has higher effectiveness and safety, which has been used as the first-line treatment of non-small cell lung cancer. In animal studies, pemetrexed was demonstrated to suppress tumor growth completely in mice with two types of transplanted human colon xenografts resistant to methotrexate. Therefore, the purpose of the study is to evaluate the safety and feasibility of intrathecal pemetrexed in patients with recurrent leptomeningeal metastases from non-small cell lung cancer.