Pembrolizumab And Lenvatinib In Leptomeningeal Metastases

This is a single arm Phase 2 study of pembrolizumab in combination with lenvatinib in patients with leptomeningeal metastases from any solid tumor. The research study procedures include screening for eligibility and study treatment, including evaluations and follow up visits. * The names of the study drugs involved in this study are: * Pembrolizumab * Lenvatinib The study treatment will last for up to 35 cycles (a cycle is 21 days long), or until the disease gets worse or unacceptable side effects. Participants will be followed for up to 90 days after the end of the study treatment. It is expected that about 19 people will take part in this research study. This research study is a Phase II clinical trial. Phase II clinical trials test the safety and effectiveness of an investigational drug combination to learn whether the drug combination works in treating a specific disease. "Investigational" means that the drug combination is being studied. The U.S. Food and Drug Administration (FDA) has not approved pembrolizumab or lenvatinib for this specific disease but each has been approved for other uses. . .