Neutrophils are the primary effector cells during inflammation, but can also control excessive inflammatory responses by secreting anti-inflammatory cytokines. However, the mechanisms modulating their plasticity remain unclear. We now show that systemic serum amyloid A-1 (SAA-1) controls the plasticity of neutrophil differentiation. SAA-1 not only induced anti-inflammatory IL-10-secreting neutrophils but also promoted invariant NKT (iNKT) cell interaction with these neutrophils, a process that limits their suppressive activity by reducing IL-10 and enhancing IL-12 production. Because SAA-1-producing melanomas promote differentiation of IL-10-secreting neutrophils, harnessing iNKT cells could be useful therapeutically by reducing the frequency of immunosuppressive neutrophils and restoring tumor specific immune responses.

BackgroundMetastatic uveal melanoma (UM) carries a poor prognosis; liver is the most frequent and often solitary site of recurrence. Available systemic treatments have not improved outcomes. Melphalan percutaneous hepatic perfusion (M‐PHP) allows selective intrahepatic delivery of high dose cytotoxic chemotherapy.MethodsRetrospective analysis of outcomes data of UM patients receiving M‐PHP at two institutions was performed. Tumor response and toxicity were evaluated using RECIST 1.1 and Common Terminology Criteria for Adverse Events (CTCAE) v4.03, respectively.ResultsA total of 51 patients received 134 M‐PHP procedures (median of 2 M‐PHPs). 25 (49%) achieved a partial (N = 22, 43.1%) or complete hepatic response (N = 3, 5.9%). In 17 (33.3%) additional patients, the disease stabilized for at least 3 months, for a hepatic disease control rate of 82.4%. After median follow‐up of 367 days, median overall progression free (PFS) and hepatic progression free survival (hPFS) was 8.1 and 9.1 months, respectively and median overall survival was 15.3 months. There were no treatment related fatalities. Non‐hematologic grade 3‐4 events were seen in 19 (37.5%) patients and were mainly coagulopathic (N = 8) and cardiovascular (N = 9).ConclusionsM‐PHP results in durable intrahepatic disease control and can form the basis for an integrated multimodality treatment approach in appropriately selected UM patients.