Finally, a recent study performed with treatment-naïve ovarian cancer patients demonstrates that IDO1 inhibition by epacadostat induces overproduction of tumoral nicotinamide adenine dinucleotide (NAD+), which reduces T-cell proliferation and functionality in vitro and mitigates IDO1 inhibitor efficacy in vivo (Figure 12G) (358). The gene discussed is IDO1; the disease is ovarian cancer.