Novel mechanisms of androgen receptor-centered transcriptional regulatory network in regulating CD8⁺ T cell exhaustion and sex bias in cancer

Sex bias in cancers arising from nonreproductive organs is known but poorly understood. We recently reported on a T cell-intrinsic role of androgen receptor (AR) in driving CD8 +T cell exhaustion which underlies the poorer tumor control in males (Kwon et al., Sci Immunol, 2022). This study aims to understand how AR regulates CD8 +tumor-infiltrating lymphocytes (TILs) by identifying its genome-wide targets. We created a CD8 +T cell-specific AR knockout (KO) mouse model by crossing E8I-cre mice with Ar-floxed mice, which we challenged with syngeneic bladder tumor MB49. We then monitored tumor growth and performed spectral flow cytometry using a T cell exhaustion panel. Further, we used Cleavage Under Targets and Tagmentation – sequencing (CUT&Tag-seq) to map the entire AR targets in CD8 +TILs. Loss of AR in CD8 +T cells significantly slowed the growth of MB49 in male but not female mice. CD8 +TILs from male CD8 AR KO mice showed reduced TOX +TCF1 −terminally exhausted subset (69%; P≤ 0.05) and TOX expression (72%; P = 0.0583) compared to controls. Similarly, TOX expression decreased by 43% in AR-deleted CD8 +T cells following chronic TCR stimulation in vitro (P ≤ 0.0001). Finally, using CUT&Tag-seq, we found that AR binds directly to promoters of multiple key transcriptional regulators of T cell exhaustion, including Tcf7 and Tox. Through identifying the genome-wide targets of AR in CD8 +TILs, we characterized the cell-intrinsic mechanism by which AR regulates CD8 +T cell exhaustion. Our work suggests AR is a master transcriptional regulator that negatively impacts CD8 +T cell immunity, which may contribute to poorer survival in males and supports combining androgen deprivation therapy with immune checkpoint blockage for cancer treatment. Special Institutional Funding