STAT1 and melanoma: IFNs can improve ICI responses as loss-of-function mutations in IFN signaling components (i.e., JAK1/2) have been identified in melanoma patients after pembrolizumab treatment relapse (Zaretsky et al, 2016), and knockout of IFN pathway mediators such as Jak1, Stat1, Ifngr1 in tumors can weaken ICI treatment efficacy (Manguso et al, 2017; Torrejon et al, 2020).