Autologous cancer cell vaccination, adoptive T-cell transfer, and interleukin-2 administration results in long-term survival for companion dogs with osteosarcoma.

This immunotherapy protocol without cytotoxic chemotherapy is safe and tolerable. Compared to historical amputation reports, survival was notably prolonged in this group of patients. Additional prospective studies are warranted to elucidate active immunologic mechanisms and further improve disease response and survival.