Oncolytic adenovirus encoding a TGF-β inhibitor synergizes with PD-1 blockade to potentiate NK cell cytotoxicity against NSCLC

TL;DR

A new triple therapy combining a PD-1 antibody, NK cells, and an oncolytic virus improves treatment of non-small cell lung cancer in mice.

Contribution

A novel triple-combination therapy using PD-1 blockade, NK cells, and an oncolytic adenovirus is shown to enhance NK cell cytotoxicity in NSCLC.

Findings

The triple therapy significantly inhibited tumor growth and increased NK cell cytotoxicity.

The treatment elevated perforin, granzyme B, and IFN-γ levels and improved lymphocyte infiltration.

The regimen demonstrated a favorable safety profile in NSCLC mouse models.

Abstract

Immune checkpoint inhibitors (ICIs) are a frontline treatment for advanced non-small cell lung cancer (NSCLC), yet 80% of the patients exhibit resistance, creating an urgent need for novel therapeutic strategies. In this study, we investigated the synergistic efficacy of a triple-combination therapy comprising a PD-1 antibody, adoptive NK (natural killer) cells, and an oncolytic adenovirus Ad-anti-TGF-βRII (encoding a TGF-β inhibitor) in NSCLC xenograft mouse models.

We investigated the combined effect of Ad-anti-TGF-βRII and NK cells on PD-1 antibody monotherapy using both in vitro cell experiments and the mouse model of NSCLC. Cytotoxicity assays, quantitative real-time PCR, and western blot analysis demonstrated that Ad-anti-TGF-βRII exhibited stronger tumor-killing activity compared to the control oncolytic adenovirus Ad-null. Furthermore, cytotoxicity assays and flow cytometry were employed to explore how the combination of Ad-anti-TGF-βRII and NK cells with PD-1 antibody promotes NK cell proliferation and activation, as well as the potent tumor-killing effect of the combination therapy. In the mouse model of NSCLC, the anti-tumor efficacy of the combination therapy was evaluated by monitoring tumor volume changes, hematoxylin and eosin (H&E) staining. The underlying mechanisms were further investigated using immunofluorescence, immunohistochemistry, quantitative real-time PCR, western blot, and flow cytometry.

The triple-combination therapy markedly inhibited tumor growth, augmented NK cell cytotoxicity and elevated the expression levels of perforin, granzyme B, and IFN-γ. Furthermore, it significantly increased lymphocyte recruitment and infiltration into tumor tissue. Comprehensive analysis demonstrated the favorable safety profile of this therapeutic regimen.

Our findings suggest that the combination of a PD-1 antibody, NK cells, and the oncolytic adenovirus Ad-anti-TGF-βRII represents a promising therapeutic strategy for NSCLC by remodeling the tumor microenvironment (TME) to overcome ICI resistance.

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