Fig. 6. In vivo activity of DTT-205 and DTT-304 in immunocompetent animals.

Mouse fibrosarcoma cells were inoculated subcutaneously in syngenic C57BL/6 animals and arising tumors were treated when palpable with repeated injections of DTT-205 or DTT-304 in the presence of absence of intraperitoneally injected CD4/CD8 blocking antibody (a). Both DTT-205 and DTT-304-induced efficient oncolysis. Immunocompetent animals depicted long-term effects whereas tumors recurred soon after treatment in immunecompromised animals upon T-cell depletion an effect that is reflected in tumor growth (b-f) and overall survival (g) (Chi² test, **p < 0.01, ***p < 0.001). Rechallenge of animals cured from MCA205 fibrosarcoma with MCA205 several weeks after the initial therapy on the contralateral and challenge with syngenic mouse TC-1 lung cancer cells on the ipsilateral side resulted in efficient rejection of MCA205 but aggressive tumor growth of TC-1 (h-k). DTT-205 and DTT-304 caused the generation of immunological memory that sufficed in rejection isogenic tumors