Leptomeningeal Metastasis from Non-Small Cell Lung Cancer and Current Landscape of Treatments.

Leptomeningeal metastasis (LM), also known as leptomeningeal carcinomatosis (LC), is a devastating complication of metastatic cancer that occurs when neoplastic cells invade the meningeal space. Diagnosis of LM remains challenging given the heterogeneous signs and symptoms at presentation and requires thorough neurological examination, cerebrospinal fluid (CSF) analysis, and magnetic resonance imaging (MRI) of the brain and spine with gadolinium. Detecting neoplastic cells in the cerebrospinal fluid is the gold standard for diagnosing leptomeningeal metastases; however, it has low sensitivity and may require multiple CSF samples. New emerging technologies, such as liquid biopsy of CSF, have increased sensitivity and specificity for detecting circulating tumor cells (CTC) in CSF. The management of LM in NSCLC patients requires an individualized multidisciplinary approach. Treatment options include surgery for ventricular shunt placement, radiation therapy to bulky or symptomatic disease sites, systemic or intrathecal chemotherapy, molecularly targeted agents, and, more recently, immunotherapy. Targeting actionable mutations in LM from NSCLC, such as epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) or anaplastic lymphoma kinase (ALK) gene rearrangement inhibitors, have shown encouraging results in terms of disease control and survival. Although there is limited data regarding the use of immunotherapy in LM, immunotherapy has produced promising results in several case reports. In this review, we focused on the epidemiology, pathophysiology, clinical presentation, diagnosis, and current treatment strategies, with a special emphasis on novel agents, including targeted therapies and immunotherapy of LM in patients with NSCLC.