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 model5–8; 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.