Therapy of autochthonous skin cancers in mice with intravenously injected liposomes containing muramyltripeptide.

Liposomes containing the immunomodulator muramyltripeptide phosphatidylethanolamine (MTP-PE) or free saline were injected i.v. into BALB/c mice with autochthonous skin cancers induced by chronic exposure to ultraviolet irradiation. Treatment with liposomes containing MTP-PE produced significant retardation in the growth of the primary autochthonous skin cancers and significantly prolonged survival of the treated mice as compared with the saline-treated controls. Since ultraviolet-irradiated mice have a defect in immunological recognition of their autochthonous tumors, the therapeutic effects of liposomes containing MTP-PE are very encouraging. These results suggest that liposomes containing MTP-PE could be used for the treatment of patients with skin cancer or other malignant diseases.