Immuno-embolization plus PD1 antibody in metastatic uveal melanoma.

Abstract

e21592 Background: More than 90% of patients with metastatic uveal melanoma (MUM) have metastatic disease in the liver. MUM has a poor prognosis following development of liver metastasis. Control of disease progression in the liver correlates with improved survival in MUM. We present a single-institution experience of treating MUM patients with immuno-embolization (IE) of liver metastasis using GM-CSF in combination with an anti-PD1 antibody (Pembrolizumab). Methods: This retrospective study includes MUM patients who received liver-directed therapy (IE) in combination with IV Pembrolizumab at the University of Iowa. Patients selected for IE treatment had liver-predominant metastatic disease involving less than 50% of the total liver parenchyma, total bilirubin < 2, serum albumin > 3, and patient ECOG PS of 0-1. Alternating lobar IE was administered every 4 weeks using a combination of GM-CSF (2000 mcg) and Lipiodol. Pembrolizumab was administered IV at 200 mg every 3 weeks. Results: 11 MUM patients received a total of 58 IE treatments concurrently with IV Pembrolizumab. 4 patients achieved stable disease, and 2 patients achieved partial response as their best radiographic response during treatment. 6 patients received additional lines of therapy; of these, 4 were enrolled into clinical trials. 5 patients were alive at the time of analysis, and 2 patients were actively receiving IE plus Pembrolizumab therapy. The median overall survival (OS) from diagnosis was 25.6 months, and the median OS from the first IE treatment was 21.3 months. Complications related to IE treatments included bleeding (n = 1), severe post-procedural pain (n = 2), infection (n = 1), and anaphylactic reaction (n = 1). No unexpected immune-related side effects occurred with Pembrolizumab. Specifically, no immune-related hepatic toxicity was reported in any patient. Conclusions: Immuno-embolization of liver metastasis using GM-CSF in combination with systemic check-point inhibitor therapy is promising in the treatment of MUM patients, and had no reported immunologic hepatic toxicity in a single-institution patient cohort. The treatment combination is currently being evaluated in a prospective clinical trial (NCT03472586).