ImmTher, a lipophilic disaccharide derivative of muramyl dipeptide, up-regulates specific monocyte cytokine genes and activates monocyte-mediated tumoricidal activity.

ImmTher, a liposome-encapsulated lipophilic disaccharide tripeptide derivative of muramyl dipeptide, previously showed activity against liver and lung colorectal metastases in a phase I trial. The purpose of the current studies was to investigate whether ImmTher could up-regulate specific cytokine gene expression and protein production, as well as activate the tumoricidal or cytostatic activity of human monocytes. ImmTher induced the expression and production of interleukin(IL)-1alpha IL-1beta, IL-6, IL-8, IL-12, macrophage chemotactic and activating factor, and tumor necrosis factor alpha but not IL-2 or IL-10. Cytostatic or cytotoxic monocyte activity was stimulated against human Ewing's sarcoma, osteosarcoma, and melanoma cells but not breast cancer cells. Production and secretion of these cytokine proteins may play a role in the antitumor activity of ImmTher.