Intrathecal Injection Pemetrexed And Bevacizumab in Patients With Leptomeningeal Metastases in NSCLC

This study is testing whether injecting two cancer drugs — pemetrexed and bevacizumab — directly into the spinal fluid (called intrathecal injection) can help control leptomeningeal metastasis, a serious condition where non-small cell lung cancer has spread to the thin membranes surrounding the brain and spinal cord. **You may be eligible if...** - You are 18 or older and have been diagnosed with non-small cell lung cancer - Your cancer has spread to the brain and spinal membranes (confirmed by spinal fluid analysis or MRI) - Your current standard treatments have not controlled this spread - Your expected survival is at least 1 month - Your blood counts and organ function meet minimum requirements **You may NOT be eligible if...** - You are HIV-positive - You are allergic to pemetrexed or bevacizumab - You have previously received either of these drugs injected into the spinal fluid - You have certain bleeding disorders, serious infections, or other conditions that make this procedure unsafe - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.