Retrospective review of metastatic melanoma patients with leptomeningeal disease treated with intrathecal interleukin-2.

Objectives: Metastatic melanoma patients with leptomeningeal disease (LMD) have an extremely poor prognosis, with a median survival measured in weeks, and few treatment options. Outcomes of a retrospective cohort of patients with LMD that were treated with intrathecal interleukin-2 (IT IL-2) were reviewed to assess the long-term efficacy of this therapy.

Methods: The records of metastatic melanoma patients with LMD who were treated with IT IL-2 from 2006 to 2014 in a Compassionate Investigational New Drug study were reviewed. IL-2 (1.2 mIU) was administered intrathecally via Ommaya reservoir up to five times per week in the inpatient setting for 4 weeks; patients with good tolerance and clinical benefit received maintenance IT IL-2 every 1-3 months thereafter.

Results: The cohort included 43 patients. The median age of the patients was 47 years (range 18-71), and 32 (74%) were male. 23 patients (53%) had positive cerebrospinal fluid (CSF) cytology and radiographic evidence of LMD, 8 (19%) had positive CSF cytology only, 9 (21%) had radiographic evidence only and 3 (7%) were diagnosed based on pathology review after craniotomy. The median overall survival (OS) from initiation of IT IL-2 was 7.8 months (range, 0.4-90.8 months), with 1-year, 2-year and 5-year OS rates of 36%, 26% and 13%. The presence of neurological symptoms (HR 2.1, P=0.03), positive baseline CSF cytology (HR 4.1, P=0.001) and concomitant use of targeted therapy (HR 3.0, P=0.02) was associated with shorter OS on univariate analysis. All patients developed symptoms due to increased intracranial pressure which was managed with supportive medications and/or CSF removal, and there were no treatment-related deaths.

Conclusion: These results demonstrate that despite their historically dismal prognosis a subset of metastatic melanoma patients with LMD treated with IT IL-2 can achieve long-term survival, but these data need to be verified in a prospective trial setting.