EGFR Oncogenic Mutations in NSCLC Impair Macrophage Phagocytosis and Mediate Innate Immune Evasion Through Upregulation of CD47

Abstract

Introduction

EGFR-mutated NSCLC is characterized by an immunosuppressive microenvironment that confers limited clinical effectiveness to anti-PD1/PD-L1 antibodies. Despite the discouraging outcomes of immunotherapy, novel immune checkpoints are constantly emerging, among which the specific vulnerability for therapeutic intervention in the context of EGFR-mutated NSCLC remains unresolved.

Methods

Datasets of patient- and cell line-levels were utilized for screening and mutual validation of association between EGFR mutation and a panel of immune checkpoint-related genes. Regulatory mechanism was elucidated through in-vitro manipulation of EGFR signaling pathway and examined by immunoblot analysis, quantitative polymerase chain reaction, flow cytometry, immunofluorescence staining and chromatin immunoprecipitation, etc. In-vivo investigation of different therapeutic strategies was conducted using both immunocompetent and immunodeficient mice models.

Results

Among all screened immune checkpoints, CD47 emerged as the candidate most relevant to EGFR activation. Mechanistically, EGFR mutation constitutively activated downstream ERK and AKT pathways to respectively upregulate the transcriptional factors c-Myc and NFκB, both of which structurally bound to the promotor region of CD47 and actively transcribed this "don't eat me" signal. Impaired macrophage phagocytosis was observed upon introduction of EGFR sensitizing mutations in NSCLC cell line models, whereas CD47 blockade restored the phagocytic capacity and augmented tumor cell killing in both in-vitro and in-vivo models. Remarkably, the combination of anti-CD47 antibody with EGFR TKI demonstrated an additive antitumor activity compared to monotherapy of either anti-tumor agent in both immunocompetent or adaptive immunity-deficient mice models.

Conclusions

EGFR sensitizing mutation facilitates NSCLC's escape from innate immune attack through upregulating CD47. Combination therapy incorporating CD47 blockade holds substantial promise for clinical translation in developing more effective therapeutic approaches against EGFR-mutant NSCLC.