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Natural killer T (iNKT) cells can help mediate immune surveillance against tumors in mice. Prior studies targeting human iNKT cells were limited to therapy of advanced cancer and led to only modest activation of innate immunity. Clinical myeloma is preceded by an asymptomatic precursor phase. Lenalidomide was shown to mediate antigen-specific costimulation of human iNKT cells. We treated 6 patients with asymptomatic myeloma with 3 cycles of combination of ct-galactosylceramide-loaded monocyte-derived dendritic cells and low-dose lenalidomide. Therapy was well tolerated and led to reduction in tumor-associated monoclonal immunoglobulin in 3 of 4 patients with measurable disease. Combination therapy led to activation-induced decline in measurable iNKT cells and activation of NK cells with an increase in NKG2D and CD56 expression. Treatment also led to activation of monocytes with an increase in CD16 expression. Each cycle of therapy was associated with induction of eosinophilia as well as an increase In serum soluble IL2 receptor. Clinical responses correlated with pre-existing or treatment-induced antitumor T-cell immunity. These data demonstrate synergistic activation of several innate immune cells by this combination and the capacity to mediate tumor regression. Combination therapies targeting iNKT cells may be of benefit toward prevention of cancer in humans. [ABSTRACT FROM AUTHOR]

Natural killer T (NKT) cells are a distinct subset of T cells that recognize lipid antigens in the context of CD1d molecules. There is a considerable body of evidence implicating a role for NKT cells in regulating antitumor immunity in mice. α-Galactosylceramide (α-GalCer) is a potent agonist ligand for type I NKT cells. We and others have shown that injection of α-GalCer-loaded dendritic cells leads to clear expansion of NKT cells in vivo in cancer patients. Preclinical studies suggest the capacity of thalidomide analogues to enhance ligand-dependent NKT activation and provide the rationale for combination approaches that are now being designed. Recently, we demonstrated the presence of CD1d-restricted T cells specific for an inflammation-associated lipid, lysophosphatidylcholine, in patients with advanced myeloma. These studies suggest that type II NKT cells may play a role in sensing and regulating inflammation. Harnessing CD1d-restricted T cells in cancer may depend on regulating the balance between type I and II NKT cells and holds promise as a broad strategy for immune therapy of several cancers. [ABSTRACT FROM AUTHOR]