TLR9 and neoplasm: In light of these immune stimulatory features, here we tested the therapeutic efficacy of a TLR9 agonist, administered intra-lesion, in immune-competent mouse models of OS demonstrating its activity not only on the treated lesion but also on a contralateral, untreated, tumor, suggesting the activation of both innate and adaptive immune response capable of inducing an abscopal effect.