CD8A and cancer: Heightened Treg accrual and elevated Treg/CD8+ T cell ratios are commonly found in the tumor microenvironment (Mandal et al., 2016; Bhaskaran et al., 2021a), and can also hinder the success of α-PD1 cancer immunotherapy (Pandiyan and Lenardo, 2008; Barron et al., 2010; Wang et al., 2012; Pierson et al., 2013; Tai et al., 2013; Nowicki et al., 2018; Wen et al., 2019; Tay et al., 2020).