Recently, efforts aiming at the improvement of ABH for cancer immunotherapy have resulted in the development of the Arginase-1 inhibitor CB-1158 (INCB001158) by Calithera Biosciences, Inc. (South San Francisco, CA) (Steggerda et al., 2017, Golebiowski et al., 2013, Van Zandt et al., 2013, Golebiowski et al., 2013). The gene discussed is ARG1; the disease is cancer.