Although the role of neutrophils in modulating antitumor T-cell responses has been extensively studied, their direct effects on tumor cells remain less well understood. In this study, we investigated whether neutrophils have the capacity to directly kill tumor cells independently of T cells. We found that anti-CD40-based therapy, when combined with IL10 receptor blockade, initiates a Batf3-dependent pathway in which IL12 and IFNγ secretion results in oncolytic neutrophil activity. Using a combination of microscopy, single-cell, and functional assays, we observed that killing of tumor cells by neutrophils is dependent on physical contact and degranulation. This degranulation-mediated killing is associated with an atypical dynamic invasive neutrophil phenotype. In line with our preclinical findings, our phase I trial of anti-CD40 shows that circulating IL12, IFNγ, and IL10 increase in response to anti-CD40, whereas our phase Ib/2 PRINCE study shows that lower circulating IL10 is associated with favorable overall survival (OS) specifically among anti-CD40-treated patients. Finally, we found that neutrophil expansion with granulocyte colony-stimulating factor is associated with improved OS, specifically in patients treated with anti-CD40, suggesting that this pathway may be amenable to therapeutic intervention in patients with advanced cancer.
