Intrathecal Pemetrexed

Cohort A receives intrathecal pemetrexed 50 mg twice in the first week and then once every 4 weeks. Cohort B uses intrathecal pemetrexed 50 mg with intrathecal bevacizumab. There are no standardised guidelines defining the optimal intrathecal pemetrexed dose or frequency for NSCLC leptomeningeal metastases. Prior NSCLC leptomeningeal metastasis studies have shown safety signals, symptom improvement, and survival benefit for intrathecal pemetrexed, but resistance remains a major problem. Intrathecal chemotherapy delivers drugs directly into the subarachnoid space and can produce higher local drug concentrations at the disease site.