Outcomes and prognostic factors in melanoma patients with leptomeningeal disease: a retrospective cohort study

Leptomeningeal disease (LMD) is a devastating complication of metastatic melanoma, affecting up to 15% of patients with central nervous system involvement. Despite advances in systemic therapy, LMD carries poor prognosis. Patients with LMD are often excluded from clinical trials. Contemporary real-world data on prognostic factors and treatment outcomes in melanoma LMD are limited. We conducted a retrospective cohort study of patients diagnosed with leptomeningeal metastasis from melanoma between 1 January 2018 and 31 December 2025, across Mayo Clinic sites. LMD diagnosis was made by magnetic resonance imaging showing leptomeningeal enhancement and confirmation from cerebrospinal fluid cytology and clinical presentation. Demographic, clinical, treatment, and outcome data were collected. Overall survival (OS) from LMD diagnosis was the primary endpoint. Forty-four patients were identified (median age: 60.0 years, range: 30.5–82.7). Before diagnosis of LMD, systemic therapy for metastatic disease was given to 91% of patients. BRAF mutations were present in 65.9%. After LMD diagnosis, 88.6% were treated for LMD. Median OS was 2.96 months (95% confidence interval: 1.39–4.53). Poor Eastern Cooperative Oncology Group performance status was independently associated with worse OS (hazard ratio: 2.10, P = 0.036). Any treatment for LMD (hazard ratio: 0.16, P = 0.005) was associated with improved OS. Melanoma-related LMD remains rapidly fatal. Studies of novel treatments are needed to improve outcomes for patients with this diagnosis.