Regression of established B16F10 melanoma with a recombinant Listeria monocytogenes vaccine

We have previously shown that Listeria monocytogenes, a Gram-positive, facu ltative intracellular bacterium, is a potent vector for targeting tumor-spe cific antigens to the immune system, In the present study, we extend these studies to the highly tumorigenic mouse melanoma B16F10, transduced with a model tumor antigen, We are able to induce the regression of primary tumors and established lung metastases by parenteral immunization with a L. monoc ytogenes recombinant that expresses the same antigen. Adjunctive therapy wi th granulocyte macrophage colony-stimulating factor or a vaccinia-based vac cine does not result in an improved cure rate over the L, monocytogenes vac cine alone, Tumor regression is accompanied by the expression of inflammato ry cytokines in the tumor.