MA11.10 Peripheral T Cell Repertoire Evolution in Resectable NSCLC Treated with Neoadjuvant PD-1 Blockade

Abstract

Neoadjuvant PD-1 blockade has emerged as a promising treatment for resectable NSCLC. The neoadjuvant setting provides a unique opportunity to examine temporal-spatial dynamics of the T cell repertoire in the peripheral and tumoral compartments in response to PD-1 blockade. T-cell receptor (TCR) repertoire dynamics and composition were assessed in matched tumor, normal lung, and longitudinal peripheral blood from 20 NSCLC patients treated with neoadjuvant nivolumab (NCT02259621) and were correlated with major pathologic response (MPR, ≤10% viable tumor in resected specimen) at the time of resection. Treatment-induced dynamics of activated T cell clonotypes were additionally evaluated using TCR sequencing (TCRseq) of flow-sorted PD-1+ T cell populations. To focus on the phenotype of on-treatment intratumoral T cell clones that were recruited from the periphery, combined single-cell RNAseq/TCRseq was performed on post-treatment tumors of 6 patients (3 MPR and 3 non-MPR). MPR was associated with a more clonal intratumoral TCR repertoire and greater clonotypic sharing between pre-treatment blood and post-treatment tumor bed relative to non-MPR. Peripheral repertoire remodeling in response to anti-PD-1 treatment correlated with increased tumor infiltration. Specifically, in patients with MPR, the post-treatment tumor bed was enriched with T cell clones that were peripherally expanded between 2-4 weeks after PD-1 blockade. Clonotypic tracking of the peripherally expanded clones revealed persistence of those clones in the periphery 1+ years following surgical resection and cessation of PD-1 blockade. Single-cell RNAseq/TCRseq analyses revealed distinct phenotypes of peripherally expanded TIL for patients with MPR, with upregulated gene programs associated with cytotoxicity and cytoprotective effects against oxidative stress. Long-term peripherally-persistent TILs had significant upregulation of genes including GZMK, DUSP2, NKG7, 4-1BB and down-regulation of CTLA-4, CXCL13 and PDCD1 as compared to short-lived clones. Our findings support the notion that neoadjuvant checkpoint blockade expands anti-tumor T cell clones in the periphery that can accumulate in tumor bed, facilitate tumor regression, and promote clonotypic persistence in the periphery. Importantly, our data demonstrate the systemic effect of neoadjuvant PD-1 blockade and indicate that the periphery may be an underappreciated originating compartment of effective anti-tumor immunity.