Prospective Evaluation Of High-Dose Systemic Methotrexate In Patients With Breast Cancer And Leptomeningeal Metastasis

This study is testing whether high-dose methotrexate given as an intravenous infusion (into the bloodstream) can treat breast cancer that has spread to the lining of the brain and spinal cord — a serious complication called leptomeningeal metastasis. **You may be eligible if...** - You are over 18 years old and in generally good physical condition - You have been diagnosed with invasive breast cancer that is triple-negative (ER-, PR-, HER2-), HER2-positive, or hormone-receptor-positive but no longer responding to hormone therapy - Your cancer has been confirmed to have spread to the lining of the brain or spinal cord - Your blood counts, kidney, and liver function are within acceptable ranges **You may NOT be eligible if...** - You have had a previous allergic reaction to methotrexate - You have severe heart failure or active mouth sores - You received chemotherapy or brain radiation within the past 2 weeks (or whole-brain radiation in the past 6 months) - You had systemic methotrexate treatment within the past year - You are currently receiving other cancer treatments - You are pregnant or breastfeeding - You take aspirin, anti-inflammatory pain medications (NSAIDs), or certain antibiotics within one week of starting treatment - You have significant fluid buildup in your abdomen or around your lungs Talk to your doctor to see if this trial is right for you.