The invention relates to prophylaxis and therapy of cancer. In particular there is provided a protein Tryptophan 2,3-dioxygenase (TDO) or peptide fragments here of that are capable of eliciting anti-cancer immune responses. Specifically, the invention relates to the use of TDO or peptides derived thereof or TDO specific T-cells for treatment of cancer. The invention thus relates to an anti-cancer vaccine which optionally may be used in combination with other immunotherapies and to TDO specific T-cells adoptively transferred or induced in vivo by vaccination as a treatment of cancer. It is an aspect of the invention that the medicaments herein provided may be used in combination with cancer chemotherapy treatment. A further aspect relates to the prophylaxis and therapy of infections by the same means as described above.