Levamisole Inhibits and Cures a Solid Malignant Tumour and its Pulmonary Metastases in Mice

Abstract

WE have reported the stimulatory effects of racemic 2,3,5,6-tetrahydro-6-phenyl-imidazo (2,1,-b) thiazole, “tetramisole” and of its l-isomer, “levamisole”, on antibacterial immunization¹ and on antibody-forming spleen cells in mice immunized with sheep red blood cells². Tetramisole restored the impaired immunological system of aged mice³. The graft vs host reaction in F1 hybrid recipients was increased following inoculation of splenic cells from a parental donor previously stimulated by injection of these drugs⁴. These results and further studies in progress suggested that tetramisole and levamisole actively stimulated cell-mediated immunity and we wished to determine the effects of levamisole on the growth of a solid metastasizing tumour. Lewis lung (3 LL) tumour of C57B1 mice provides a good experimental model^5–8; it has a rapid subcutaneous growth and the macroscopic pulmonary metastases can be easily counted 3 weeks after tumour inoculation⁸. We report the activity of levamisole against the growth of the primary subcutaneous 3 LL tumour and against the development of pulmonary metastases.