While this mechanism may seem dangerous if successful, clinical data have been solid in melanoma by targeting indoleamine 2,3-dioxygenase 1 (IDO1) and PD-L1 with peptide vaccines [67] and attempts are being made to diversify by targeting other molecules and suppressive cell types such as transforming growth factor beta (TGF-beta) [68]. The gene discussed is IDO1; the disease is melanoma.