show Abstracthide AbstractIn the K14-HPV16 transgenic mouse model of squamous carcinogenesis, activation of C5a receptor (C5aR1) in early neoplastic tissues fosters protumorigenic properties of C5aR1+ mast cells and macrophages, and in turn, suppression of CD8+ T cell cytotoxicity. Therapeutic inhibition of C5a receptor (C5aR1) with a peptide antagonist improved efficacy to paclitaxel chemotherapy associated with CXCR3-dependent CD8+ T cell activation. To investigate the effects of combination therapy on the T cell repertoire, we performed deep sequencing of the complementarity-determining region (CDR) 3 of the T cell receptor (TCR)b chain in matched tumor lysates and peripheral blood mononuclear cells (PBMCs). Intratumoral TCRß clonotypes were hyperexpanded and increasingly detected in matched peripherally-expanded T cell populations, thereby implicating antigen-dependent peripheral priming in response to systemic C5aR1 inhibition. Overall design: Deep sequencing of the complementarity-determining region (CDR) 3 of the T cell receptor (TCR)b chain in matched tumor lysates and peripheral blood mononuclear cells (PBMCs)