Sexual Dimorphism in T Cell Exhaustion and Bladder Cancer

PROJECT 1 – SUMMARY Sex is an understudied biological variable with significant influence on immune function, including in the context of cancer. However, the immunological mechanisms underlying the sex bias seen in cancers from non- reproductive organs, such as bladder cancer (BC), remain elusive. Male bias in BC incidence persists after adjustment for other known risk factors suggesting a fundamental biological basis for this sexual dimorphism. Objective: To define the molecular mechanisms by which androgens, AR target genes, and sex chromosome- encoded epigenetic modifiers contribute to sex differences in CD8+ T cell exhaustion in the tumor microenvironment (TME). Impact: Our study will uncover an immunological basis and mechanism by which CD8+ T cell exhaustion contributes to sex bias in BC, with implications for improving ICB approaches for all cancer via three specific aims. Aim 1: Determine the role of AR-TCF1 and AR-TOX in CD8+ T cell exhaustion and tumor control. The molecular mechanisms by which androgens influence T cells and contribute to cancer progression are unclear. Male CD8+ tumor-infiltrating lymphocytes (TILs) preferentially adopt a TCF1+ PE state due to direct activation of Tcf7 by AR. Hypothesis. Androgen signaling establishes a stable TCF1-driven transcriptional network in CD8+ T cells that favors exhaustion, through the modulation of TOX, another critical transcription factor (TF) that promotes T cell exhaustion. Aim 2: Determine the role of AR-ZFP148 in T cell effector differentiation. TF ZFP148 regulates cell proliferation and survival in non-immune cell types but has not been studied in T cell biology. Single-cell RNA-seq analyses demonstrated male-biased Zfp148 expression and regulatory activity in PE CD8+ T cells stimulated by AR. T cell receptor (TCR) engagement and chronic exhaustion induced Zfp148 expression in CD8+ T cells, and its deletion led to better effector function in vitro. The in vivo persistence of Zfp148 null T cells was compromised. Hypothesis. AR-regulated ZFP148 can suppress CD8+ T cell effector function and contributes to male-biased BC. Aim 3: Investigate the role of AR and epigenetic modifiers in CD8+ T cell exhaustion and tumor response to immunotherapy. The impact of sex chromosome-encoded epigenetic modifiers in BC – including KDM5D, UTY, and KDM6A – on immunity especially in the CD8+ compartment is a major gap in the field. In collaboration with Project 2, we found that loss of the Y chromosome (LOY) (especially the genes Kdm5d and Uty) contributes to CD8+ T cell exhaustion in BC. Hypothesis. Sex hormones and sex chromosome-encoded epigenetic modifiers contribute to CD8+ T cell exhaustion and BC sensitivity to ICB.