Evaluate the Safety, Tolerability, Biodistribution Characteristics and Preliminary Efficacy of BioTTT001

This early-phase study is testing a new drug called BioTTT001 delivered directly into the fluid around the brain and spinal cord. It is designed for people with non-small cell lung cancer (NSCLC) that has spread to the lining of the brain — a serious condition called leptomeningeal metastasis. **You may be eligible if...** - You are between 18 and 70 years old - You have NSCLC confirmed by biopsy that has spread to the fluid around the brain, confirmed by MRI or spinal fluid analysis - Your cancer continued to progress after standard treatments - Your doctor believes you are suitable for a device called an Ommaya reservoir (a small device placed under the scalp to deliver medication) - Your liver, kidneys, and blood counts are within acceptable ranges - Your life expectancy is at least 3 months **You may NOT be eligible if...** - You have uncontrolled seizures - You have brainstem tumors or rapidly spreading brain involvement - You have had serious bleeding events or blood clotting disorders - You have active serious infections or uncontrolled HIV, hepatitis B, or hepatitis C - You have a history of organ transplantation - You are pregnant or breastfeeding - You have received systemic cancer treatment (not including immunotherapy) within the past 2 weeks Talk to your doctor to see if this trial is right for you.