Cancer immunotherapy: synthetic and natural peptides in the balance

The identification of human tumor-associated antigens has opened new avenue s for immune intervention in cancer. Clinical trials using synthetic peptid es that match segments of known tumor-associated proteins are ongoing. Alte rnatively, naturally processed peptides, obtained by acid treatment of tumo r cells can be used. Here, Matteo Bellone and colleagues discuss the advant ages and disadvantages of synthetic versus natural tumor peptides in cancer immunotherapy.