To determine the safety of intrathecal (IT) PD1 antibody for Intrathecal application of PD1 antibody in metastatic solid tumors with leptomeningeal disease of solid tumors.
Patient aged ≥ 18 years at the time of signing the informed consent
Existing ability to understand and voluntarily sign an informed consent document prior to any study related assessments/procedures
Patient is at "good risk" ( NCCN guidelines version 1.2021)
Existence of the following Tumor board protocol confirmations: clinical recommendation for intrathecal therapy and evaluation of trial enrolment & statement on the potential necessity of additional systemic treatment of metastatic tumor outside the CNS
Women during pregnancy and lactation.
Previous intrathecal nivolumab application.
Patient at "poor risk" (NCCN guidelines version 1.2021)
The following differential diagnoses to LMD are exclusion criteria: a. Aseptic, meningitis b. Viral meningitis, c. Bacterial meningitis