Abstract 3245: Durvalumab induces an NK cell response associated with clinical benefit of patients with advanced NSCLC

Abstract

Abstract Introduction: The role of CD8 cells in determining clinical outcome to programmed death ligand-1 (PD-L1) blocking treatments has been well characterized, however, the contribution of NK cells is not well understood. This is partly due to the paucity of NK cell-specific markers that can identify NK cells in the tumor microenvironment (TME). We developed an NK cell-specific transcriptional signature to estimate the NK cell abundance in the TME. This signature, together with NK-chemokines shown to modulate the priming of adaptive immunity1 were investigated in patients with advanced non-small cell lung cancer (NSCLC) treated with a PD-L1 inhibitor, durvalumab. Methods: Peripheral blood mononuclear cells (PBMCs) and Fluorescence-Activated Cell Sorted (FACS) NK/ CD8 populations from three heathy donors were subjected to single cell RNA sequencing (scRNAseq, 10X Genomics) and transcriptome analysis (Affymetrix), respectively. Fresh frozen tumor biopsies from 97 NSCLC were profiled with RNA sequencing prior to durvalumab treatment; 29 of these had paired tumors procured 29 days following treatment with durvalumab. Kaplan Meier (KM) analyses were performed to identify predictive effects of the NK cell-specific signature. Clinical trial:1108/NCT01693562 Results: Transcripts over-expressed in sorted NK relative to CD8 cells were first identified (p <0.01; fold >3) and intersected with 28 mRNAs up-regulated in the NK cell cluster determined by scRNAseq, providing an 8 gene NK cell-specific transcriptional signature defined as MEDI-NK. MEDI-NK correlated with NK signatures recently described2, and included chemokines shown to induce an effective NK- response1. When evaluated in TCGA, higher expression of MEDI-NK was associated with good prognosis (Overall Survival, OS) of patients with melanoma and breast cancer (p value =0.03 and =0.001, respectively). At baseline, MEDI-NK was highly correlated with the previously identified IFNγ signature3 and was associated with Progression Free Survival (PFS p value < 0.02) of NSCLC patients treated with durvalumab. Following treatment with durvalumab, the increased expression of MEDI-NK and of additional genes leading to NK-priming of adaptive immunity1 was observed to be associated with patients’ overall survival (OS p value <0.01). Similar findings were not observed prior to durvalumab treatment. Conclusions: Using single cell analysis, an NK cell-specific signature was developed to better define the role of NK cells in anti-PDL1 therapy. The increased expressions of the NK cell-specific signature and of genes leading to NK-cell priming of adaptive immune response were associated with clinical benefit to durvalumab.